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// SPDX-License-Identifier: GPL-2.0

/* Copyright (c) 2012-2018, The Linux Foundation. All rights reserved.
 * Copyright (C) 2019-2022 Linaro Ltd.
 */

#include <linux/types.h>
#include <linux/device.h>
#include <linux/slab.h>
#include <linux/bitfield.h>
#include <linux/if_rmnet.h>
#include <linux/dma-direction.h>

#include "gsi.h"
#include "gsi_trans.h"
#include "ipa.h"
#include "ipa_data.h"
#include "ipa_endpoint.h"
#include "ipa_cmd.h"
#include "ipa_mem.h"
#include "ipa_modem.h"
#include "ipa_table.h"
#include "ipa_gsi.h"
#include "ipa_power.h"

/* Hardware is told about receive buffers once a "batch" has been queued */
#define IPA_REPLENISH_BATCH     16              /* Must be non-zero */

/* The amount of RX buffer space consumed by standard skb overhead */
#define IPA_RX_BUFFER_OVERHEAD  (PAGE_SIZE - SKB_MAX_ORDER(NET_SKB_PAD, 0))

/* Where to find the QMAP mux_id for a packet within modem-supplied metadata */
#define IPA_ENDPOINT_QMAP_METADATA_MASK         0x000000ff /* host byte order */

#define IPA_ENDPOINT_RESET_AGGR_RETRY_MAX       3

/** enum ipa_status_opcode - status element opcode hardware values */
enum ipa_status_opcode {
        IPA_STATUS_OPCODE_PACKET                = 0x01,
        IPA_STATUS_OPCODE_DROPPED_PACKET        = 0x04,
        IPA_STATUS_OPCODE_SUSPENDED_PACKET      = 0x08,
        IPA_STATUS_OPCODE_PACKET_2ND_PASS       = 0x40,
};

/** enum ipa_status_exception - status element exception type */
enum ipa_status_exception {
        /* 0 means no exception */
        IPA_STATUS_EXCEPTION_DEAGGR             = 0x01,
};

/* Status element provided by hardware */
struct ipa_status {
        u8 opcode;              /* enum ipa_status_opcode */
        u8 exception;           /* enum ipa_status_exception */
        __le16 mask;
        __le16 pkt_len;
        u8 endp_src_idx;
        u8 endp_dst_idx;
        __le32 metadata;
        __le32 flags1;
        __le64 flags2;
        __le32 flags3;
        __le32 flags4;
};

/* Field masks for struct ipa_status structure fields */
#define IPA_STATUS_MASK_TAG_VALID_FMASK         GENMASK(4, 4)
#define IPA_STATUS_SRC_IDX_FMASK                GENMASK(4, 0)
#define IPA_STATUS_DST_IDX_FMASK                GENMASK(4, 0)
#define IPA_STATUS_FLAGS1_RT_RULE_ID_FMASK      GENMASK(31, 22)
#define IPA_STATUS_FLAGS2_TAG_FMASK             GENMASK_ULL(63, 16)

/* Compute the aggregation size value to use for a given buffer size */
static u32 ipa_aggr_size_kb(u32 rx_buffer_size, bool aggr_hard_limit)
{
        /* A hard aggregation limit will not be crossed; aggregation closes
         * if saving incoming data would cross the hard byte limit boundary.
         *
         * With a soft limit, aggregation closes *after* the size boundary
         * has been crossed.  In that case the limit must leave enough space
         * after that limit to receive a full MTU of data plus overhead.
         */
        if (!aggr_hard_limit)
                rx_buffer_size -= IPA_MTU + IPA_RX_BUFFER_OVERHEAD;

        /* The byte limit is encoded as a number of kilobytes */

        return rx_buffer_size / SZ_1K;
}

static bool ipa_endpoint_data_valid_one(struct ipa *ipa, u32 count,
                            const struct ipa_gsi_endpoint_data *all_data,
                            const struct ipa_gsi_endpoint_data *data)
{
        const struct ipa_gsi_endpoint_data *other_data;
        struct device *dev = &ipa->pdev->dev;
        enum ipa_endpoint_name other_name;

        if (ipa_gsi_endpoint_data_empty(data))
                return true;

        if (!data->toward_ipa) {
                const struct ipa_endpoint_rx *rx_config;
                const struct ipa_reg *reg;
                u32 buffer_size;
                u32 aggr_size;
                u32 limit;

                if (data->endpoint.filter_support) {
                        dev_err(dev, "filtering not supported for "
                                        "RX endpoint %u\n",
                                data->endpoint_id);
                        return false;
                }

                /* Nothing more to check for non-AP RX */
                if (data->ee_id != GSI_EE_AP)
                        return true;

                rx_config = &data->endpoint.config.rx;

                /* The buffer size must hold an MTU plus overhead */
                buffer_size = rx_config->buffer_size;
                limit = IPA_MTU + IPA_RX_BUFFER_OVERHEAD;
                if (buffer_size < limit) {
                        dev_err(dev, "RX buffer size too small for RX endpoint %u (%u < %u)\n",
                                data->endpoint_id, buffer_size, limit);
                        return false;
                }

                if (!data->endpoint.config.aggregation) {
                        bool result = true;

                        /* No aggregation; check for bogus aggregation data */
                        if (rx_config->aggr_time_limit) {
                                dev_err(dev,
                                        "time limit with no aggregation for RX endpoint %u\n",
                                        data->endpoint_id);
                                result = false;
                        }

                        if (rx_config->aggr_hard_limit) {
                                dev_err(dev, "hard limit with no aggregation for RX endpoint %u\n",
                                        data->endpoint_id);
                                result = false;
                        }

                        if (rx_config->aggr_close_eof) {
                                dev_err(dev, "close EOF with no aggregation for RX endpoint %u\n",
                                        data->endpoint_id);
                                result = false;
                        }

                        return result;  /* Nothing more to check */
                }

                /* For an endpoint supporting receive aggregation, the byte
                 * limit defines the point at which aggregation closes.  This
                 * check ensures the receive buffer size doesn't result in a
                 * limit that exceeds what's representable in the aggregation
                 * byte limit field.
                 */
                aggr_size = ipa_aggr_size_kb(buffer_size - NET_SKB_PAD,
                                             rx_config->aggr_hard_limit);
                reg = ipa_reg(ipa, ENDP_INIT_AGGR);

                limit = ipa_reg_field_max(reg, BYTE_LIMIT);
                if (aggr_size > limit) {
                        dev_err(dev, "aggregated size too large for RX endpoint %u (%u KB > %u KB)\n",
                                data->endpoint_id, aggr_size, limit);

                        return false;
                }

                return true;    /* Nothing more to check for RX */
        }

        /* Starting with IPA v4.5 sequencer replication is obsolete */
        if (ipa->version >= IPA_VERSION_4_5) {
                if (data->endpoint.config.tx.seq_rep_type) {
                        dev_err(dev, "no-zero seq_rep_type TX endpoint %u\n",
                                data->endpoint_id);
                        return false;
                }
        }

        if (data->endpoint.config.status_enable) {
                other_name = data->endpoint.config.tx.status_endpoint;
                if (other_name >= count) {
                        dev_err(dev, "status endpoint name %u out of range "
                                        "for endpoint %u\n",
                                other_name, data->endpoint_id);
                        return false;
                }

                /* Status endpoint must be defined... */
                other_data = &all_data[other_name];
                if (ipa_gsi_endpoint_data_empty(other_data)) {
                        dev_err(dev, "DMA endpoint name %u undefined "
                                        "for endpoint %u\n",
                                other_name, data->endpoint_id);
                        return false;
                }

                /* ...and has to be an RX endpoint... */
                if (other_data->toward_ipa) {
                        dev_err(dev,
                                "status endpoint for endpoint %u not RX\n",
                                data->endpoint_id);
                        return false;
                }

                /* ...and if it's to be an AP endpoint... */
                if (other_data->ee_id == GSI_EE_AP) {
                        /* ...make sure it has status enabled. */
                        if (!other_data->endpoint.config.status_enable) {
                                dev_err(dev,
                                        "status not enabled for endpoint %u\n",
                                        other_data->endpoint_id);
                                return false;
                        }
                }
        }

        if (data->endpoint.config.dma_mode) {
                other_name = data->endpoint.config.dma_endpoint;
                if (other_name >= count) {
                        dev_err(dev, "DMA endpoint name %u out of range "
                                        "for endpoint %u\n",
                                other_name, data->endpoint_id);
                        return false;
                }

                other_data = &all_data[other_name];
                if (ipa_gsi_endpoint_data_empty(other_data)) {
                        dev_err(dev, "DMA endpoint name %u undefined "
                                        "for endpoint %u\n",
                                other_name, data->endpoint_id);
                        return false;
                }
        }

        return true;
}

/* Validate endpoint configuration data.  Return max defined endpoint ID */
static u32 ipa_endpoint_max(struct ipa *ipa, u32 count,
                            const struct ipa_gsi_endpoint_data *data)
{
        const struct ipa_gsi_endpoint_data *dp = data;
        struct device *dev = &ipa->pdev->dev;
        enum ipa_endpoint_name name;
        u32 max;

        if (count > IPA_ENDPOINT_COUNT) {
                dev_err(dev, "too many endpoints specified (%u > %u)\n",
                        count, IPA_ENDPOINT_COUNT);
                return 0;
        }

        /* Make sure needed endpoints have defined data */
        if (ipa_gsi_endpoint_data_empty(&data[IPA_ENDPOINT_AP_COMMAND_TX])) {
                dev_err(dev, "command TX endpoint not defined\n");
                return 0;
        }
        if (ipa_gsi_endpoint_data_empty(&data[IPA_ENDPOINT_AP_LAN_RX])) {
                dev_err(dev, "LAN RX endpoint not defined\n");
                return 0;
        }
        if (ipa_gsi_endpoint_data_empty(&data[IPA_ENDPOINT_AP_MODEM_TX])) {
                dev_err(dev, "AP->modem TX endpoint not defined\n");
                return 0;
        }
        if (ipa_gsi_endpoint_data_empty(&data[IPA_ENDPOINT_AP_MODEM_RX])) {
                dev_err(dev, "AP<-modem RX endpoint not defined\n");
                return 0;
        }

        max = 0;
        for (name = 0; name < count; name++, dp++) {
                if (!ipa_endpoint_data_valid_one(ipa, count, data, dp))
                        return 0;
                max = max_t(u32, max, dp->endpoint_id);
        }

        return max;
}

/* Allocate a transaction to use on a non-command endpoint */
static struct gsi_trans *ipa_endpoint_trans_alloc(struct ipa_endpoint *endpoint,
                                                  u32 tre_count)
{
        struct gsi *gsi = &endpoint->ipa->gsi;
        u32 channel_id = endpoint->channel_id;
        enum dma_data_direction direction;

        direction = endpoint->toward_ipa ? DMA_TO_DEVICE : DMA_FROM_DEVICE;

        return gsi_channel_trans_alloc(gsi, channel_id, tre_count, direction);
}

/* suspend_delay represents suspend for RX, delay for TX endpoints.
 * Note that suspend is not supported starting with IPA v4.0, and
 * delay mode should not be used starting with IPA v4.2.
 */
static bool
ipa_endpoint_init_ctrl(struct ipa_endpoint *endpoint, bool suspend_delay)
{
        struct ipa *ipa = endpoint->ipa;
        const struct ipa_reg *reg;
        u32 field_id;
        u32 offset;
        bool state;
        u32 mask;
        u32 val;

        if (endpoint->toward_ipa)
                WARN_ON(ipa->version >= IPA_VERSION_4_2);
        else
                WARN_ON(ipa->version >= IPA_VERSION_4_0);

        reg = ipa_reg(ipa, ENDP_INIT_CTRL);
        offset = ipa_reg_n_offset(reg, endpoint->endpoint_id);
        val = ioread32(ipa->reg_virt + offset);

        field_id = endpoint->toward_ipa ? ENDP_DELAY : ENDP_SUSPEND;
        mask = ipa_reg_bit(reg, field_id);

        state = !!(val & mask);

        /* Don't bother if it's already in the requested state */
        if (suspend_delay != state) {
                val ^= mask;
                iowrite32(val, ipa->reg_virt + offset);
        }

        return state;
}

/* We don't care what the previous state was for delay mode */
static void
ipa_endpoint_program_delay(struct ipa_endpoint *endpoint, bool enable)
{
        /* Delay mode should not be used for IPA v4.2+ */
        WARN_ON(endpoint->ipa->version >= IPA_VERSION_4_2);
        WARN_ON(!endpoint->toward_ipa);

        (void)ipa_endpoint_init_ctrl(endpoint, enable);
}

static bool ipa_endpoint_aggr_active(struct ipa_endpoint *endpoint)
{
        u32 endpoint_id = endpoint->endpoint_id;
        struct ipa *ipa = endpoint->ipa;
        u32 unit = endpoint_id / 32;
        const struct ipa_reg *reg;
        u32 val;

        WARN_ON(!test_bit(endpoint_id, ipa->available));

        reg = ipa_reg(ipa, STATE_AGGR_ACTIVE);
        val = ioread32(ipa->reg_virt + ipa_reg_n_offset(reg, unit));

        return !!(val & BIT(endpoint_id % 32));
}

static void ipa_endpoint_force_close(struct ipa_endpoint *endpoint)
{
        u32 endpoint_id = endpoint->endpoint_id;
        u32 mask = BIT(endpoint_id % 32);
        struct ipa *ipa = endpoint->ipa;
        u32 unit = endpoint_id / 32;
        const struct ipa_reg *reg;

        WARN_ON(!test_bit(endpoint_id, ipa->available));

        reg = ipa_reg(ipa, AGGR_FORCE_CLOSE);
        iowrite32(mask, ipa->reg_virt + ipa_reg_n_offset(reg, unit));
}

/**
 * ipa_endpoint_suspend_aggr() - Emulate suspend interrupt
 * @endpoint:   Endpoint on which to emulate a suspend
 *
 *  Emulate suspend IPA interrupt to unsuspend an endpoint suspended
 *  with an open aggregation frame.  This is to work around a hardware
 *  issue in IPA version 3.5.1 where the suspend interrupt will not be
 *  generated when it should be.
 */
static void ipa_endpoint_suspend_aggr(struct ipa_endpoint *endpoint)
{
        struct ipa *ipa = endpoint->ipa;

        if (!endpoint->config.aggregation)
                return;

        /* Nothing to do if the endpoint doesn't have aggregation open */
        if (!ipa_endpoint_aggr_active(endpoint))
                return;

        /* Force close aggregation */
        ipa_endpoint_force_close(endpoint);

        ipa_interrupt_simulate_suspend(ipa->interrupt);
}

/* Returns previous suspend state (true means suspend was enabled) */
static bool
ipa_endpoint_program_suspend(struct ipa_endpoint *endpoint, bool enable)
{
        bool suspended;

        if (endpoint->ipa->version >= IPA_VERSION_4_0)
                return enable;  /* For IPA v4.0+, no change made */

        WARN_ON(endpoint->toward_ipa);

        suspended = ipa_endpoint_init_ctrl(endpoint, enable);

        /* A client suspended with an open aggregation frame will not
         * generate a SUSPEND IPA interrupt.  If enabling suspend, have
         * ipa_endpoint_suspend_aggr() handle this.
         */
        if (enable && !suspended)
                ipa_endpoint_suspend_aggr(endpoint);

        return suspended;
}

/* Put all modem RX endpoints into suspend mode, and stop transmission
 * on all modem TX endpoints.  Prior to IPA v4.2, endpoint DELAY mode is
 * used for TX endpoints; starting with IPA v4.2 we use GSI channel flow
 * control instead.
 */
void ipa_endpoint_modem_pause_all(struct ipa *ipa, bool enable)
{
        u32 endpoint_id = 0;

        while (endpoint_id < ipa->endpoint_count) {
                struct ipa_endpoint *endpoint = &ipa->endpoint[endpoint_id++];

                if (endpoint->ee_id != GSI_EE_MODEM)
                        continue;

                if (!endpoint->toward_ipa)
                        (void)ipa_endpoint_program_suspend(endpoint, enable);
                else if (ipa->version < IPA_VERSION_4_2)
                        ipa_endpoint_program_delay(endpoint, enable);
                else
                        gsi_modem_channel_flow_control(&ipa->gsi,
                                                       endpoint->channel_id,
                                                       enable);
        }
}

/* Reset all modem endpoints to use the default exception endpoint */
int ipa_endpoint_modem_exception_reset_all(struct ipa *ipa)
{
        struct gsi_trans *trans;
        u32 endpoint_id;
        u32 count;

        /* We need one command per modem TX endpoint, plus the commands
         * that clear the pipeline.
         */
        count = ipa->modem_tx_count + ipa_cmd_pipeline_clear_count();
        trans = ipa_cmd_trans_alloc(ipa, count);
        if (!trans) {
                dev_err(&ipa->pdev->dev,
                        "no transaction to reset modem exception endpoints\n");
                return -EBUSY;
        }

        for_each_set_bit(endpoint_id, ipa->defined, ipa->endpoint_count) {
                struct ipa_endpoint *endpoint;
                const struct ipa_reg *reg;
                u32 offset;

                /* We only reset modem TX endpoints */
                endpoint = &ipa->endpoint[endpoint_id];
                if (!(endpoint->ee_id == GSI_EE_MODEM && endpoint->toward_ipa))
                        continue;

                reg = ipa_reg(ipa, ENDP_STATUS);
                offset = ipa_reg_n_offset(reg, endpoint_id);

                /* Value written is 0, and all bits are updated.  That
                 * means status is disabled on the endpoint, and as a
                 * result all other fields in the register are ignored.
                 */
                ipa_cmd_register_write_add(trans, offset, 0, ~0, false);
        }

        ipa_cmd_pipeline_clear_add(trans);

        gsi_trans_commit_wait(trans);

        ipa_cmd_pipeline_clear_wait(ipa);

        return 0;
}

static void ipa_endpoint_init_cfg(struct ipa_endpoint *endpoint)
{
        u32 endpoint_id = endpoint->endpoint_id;
        struct ipa *ipa = endpoint->ipa;
        enum ipa_cs_offload_en enabled;
        const struct ipa_reg *reg;
        u32 val = 0;

        reg = ipa_reg(ipa, ENDP_INIT_CFG);
        /* FRAG_OFFLOAD_EN is 0 */
        if (endpoint->config.checksum) {
                enum ipa_version version = ipa->version;

                if (endpoint->toward_ipa) {
                        u32 off;

                        /* Checksum header offset is in 4-byte units */
                        off = sizeof(struct rmnet_map_header) / sizeof(u32);
                        val |= ipa_reg_encode(reg, CS_METADATA_HDR_OFFSET, off);

                        enabled = version < IPA_VERSION_4_5
                                        ? IPA_CS_OFFLOAD_UL
                                        : IPA_CS_OFFLOAD_INLINE;
                } else {
                        enabled = version < IPA_VERSION_4_5
                                        ? IPA_CS_OFFLOAD_DL
                                        : IPA_CS_OFFLOAD_INLINE;
                }
        } else {
                enabled = IPA_CS_OFFLOAD_NONE;
        }
        val |= ipa_reg_encode(reg, CS_OFFLOAD_EN, enabled);
        /* CS_GEN_QMB_MASTER_SEL is 0 */

        iowrite32(val, ipa->reg_virt + ipa_reg_n_offset(reg, endpoint_id));
}

static void ipa_endpoint_init_nat(struct ipa_endpoint *endpoint)
{
        u32 endpoint_id = endpoint->endpoint_id;
        struct ipa *ipa = endpoint->ipa;
        const struct ipa_reg *reg;
        u32 val;

        if (!endpoint->toward_ipa)
                return;

        reg = ipa_reg(ipa, ENDP_INIT_NAT);
        val = ipa_reg_encode(reg, NAT_EN, IPA_NAT_BYPASS);

        iowrite32(val, ipa->reg_virt + ipa_reg_n_offset(reg, endpoint_id));
}

static u32
ipa_qmap_header_size(enum ipa_version version, struct ipa_endpoint *endpoint)
{
        u32 header_size = sizeof(struct rmnet_map_header);

        /* Without checksum offload, we just have the MAP header */
        if (!endpoint->config.checksum)
                return header_size;

        if (version < IPA_VERSION_4_5) {
                /* Checksum header inserted for AP TX endpoints only */
                if (endpoint->toward_ipa)
                        header_size += sizeof(struct rmnet_map_ul_csum_header);
        } else {
                /* Checksum header is used in both directions */
                header_size += sizeof(struct rmnet_map_v5_csum_header);
        }

        return header_size;
}

/* Encoded value for ENDP_INIT_HDR register HDR_LEN* field(s) */
static u32 ipa_header_size_encode(enum ipa_version version,
                                  const struct ipa_reg *reg, u32 header_size)
{
        u32 field_max = ipa_reg_field_max(reg, HDR_LEN);
        u32 val;

        /* We know field_max can be used as a mask (2^n - 1) */
        val = ipa_reg_encode(reg, HDR_LEN, header_size & field_max);
        if (version < IPA_VERSION_4_5) {
                WARN_ON(header_size > field_max);
                return val;
        }

        /* IPA v4.5 adds a few more most-significant bits */
        header_size >>= hweight32(field_max);
        WARN_ON(header_size > ipa_reg_field_max(reg, HDR_LEN_MSB));
        val |= ipa_reg_encode(reg, HDR_LEN_MSB, header_size);

        return val;
}

/* Encoded value for ENDP_INIT_HDR register OFST_METADATA* field(s) */
static u32 ipa_metadata_offset_encode(enum ipa_version version,
                                      const struct ipa_reg *reg, u32 offset)
{
        u32 field_max = ipa_reg_field_max(reg, HDR_OFST_METADATA);
        u32 val;

        /* We know field_max can be used as a mask (2^n - 1) */
        val = ipa_reg_encode(reg, HDR_OFST_METADATA, offset);
        if (version < IPA_VERSION_4_5) {
                WARN_ON(offset > field_max);
                return val;
        }

        /* IPA v4.5 adds a few more most-significant bits */
        offset >>= hweight32(field_max);
        WARN_ON(offset > ipa_reg_field_max(reg, HDR_OFST_METADATA_MSB));
        val |= ipa_reg_encode(reg, HDR_OFST_METADATA_MSB, offset);

        return val;
}

/**
 * ipa_endpoint_init_hdr() - Initialize HDR endpoint configuration register
 * @endpoint:   Endpoint pointer
 *
 * We program QMAP endpoints so each packet received is preceded by a QMAP
 * header structure.  The QMAP header contains a 1-byte mux_id and 2-byte
 * packet size field, and we have the IPA hardware populate both for each
 * received packet.  The header is configured (in the HDR_EXT register)
 * to use big endian format.
 *
 * The packet size is written into the QMAP header's pkt_len field.  That
 * location is defined here using the HDR_OFST_PKT_SIZE field.
 *
 * The mux_id comes from a 4-byte metadata value supplied with each packet
 * by the modem.  It is *not* a QMAP header, but it does contain the mux_id
 * value that we want, in its low-order byte.  A bitmask defined in the
 * endpoint's METADATA_MASK register defines which byte within the modem
 * metadata contains the mux_id.  And the OFST_METADATA field programmed
 * here indicates where the extracted byte should be placed within the QMAP
 * header.
 */
static void ipa_endpoint_init_hdr(struct ipa_endpoint *endpoint)
{
        u32 endpoint_id = endpoint->endpoint_id;
        struct ipa *ipa = endpoint->ipa;
        const struct ipa_reg *reg;
        u32 val = 0;

        reg = ipa_reg(ipa, ENDP_INIT_HDR);
        if (endpoint->config.qmap) {
                enum ipa_version version = ipa->version;
                size_t header_size;

                header_size = ipa_qmap_header_size(version, endpoint);
                val = ipa_header_size_encode(version, reg, header_size);

                /* Define how to fill fields in a received QMAP header */
                if (!endpoint->toward_ipa) {
                        u32 off;     /* Field offset within header */

                        /* Where IPA will write the metadata value */
                        off = offsetof(struct rmnet_map_header, mux_id);
                        val |= ipa_metadata_offset_encode(version, reg, off);

                        /* Where IPA will write the length */
                        off = offsetof(struct rmnet_map_header, pkt_len);
                        /* Upper bits are stored in HDR_EXT with IPA v4.5 */
                        if (version >= IPA_VERSION_4_5)
                                off &= ipa_reg_field_max(reg, HDR_OFST_PKT_SIZE);

                        val |= ipa_reg_bit(reg, HDR_OFST_PKT_SIZE_VALID);
                        val |= ipa_reg_encode(reg, HDR_OFST_PKT_SIZE, off);
                }
                /* For QMAP TX, metadata offset is 0 (modem assumes this) */
                val |= ipa_reg_bit(reg, HDR_OFST_METADATA_VALID);

                /* HDR_ADDITIONAL_CONST_LEN is 0; (RX only) */
                /* HDR_A5_MUX is 0 */
                /* HDR_LEN_INC_DEAGG_HDR is 0 */
                /* HDR_METADATA_REG_VALID is 0 (TX only, version < v4.5) */
        }

        iowrite32(val, ipa->reg_virt + ipa_reg_n_offset(reg, endpoint_id));
}

static void ipa_endpoint_init_hdr_ext(struct ipa_endpoint *endpoint)
{
        u32 pad_align = endpoint->config.rx.pad_align;
        u32 endpoint_id = endpoint->endpoint_id;
        struct ipa *ipa = endpoint->ipa;
        const struct ipa_reg *reg;
        u32 val = 0;

        reg = ipa_reg(ipa, ENDP_INIT_HDR_EXT);
        if (endpoint->config.qmap) {
                /* We have a header, so we must specify its endianness */
                val |= ipa_reg_bit(reg, HDR_ENDIANNESS);        /* big endian */

                /* A QMAP header contains a 6 bit pad field at offset 0.
                 * The RMNet driver assumes this field is meaningful in
                 * packets it receives, and assumes the header's payload
                 * length includes that padding.  The RMNet driver does
                 * *not* pad packets it sends, however, so the pad field
                 * (although 0) should be ignored.
                 */
                if (!endpoint->toward_ipa) {
                        val |= ipa_reg_bit(reg, HDR_TOTAL_LEN_OR_PAD_VALID);
                        /* HDR_TOTAL_LEN_OR_PAD is 0 (pad, not total_len) */
                        val |= ipa_reg_bit(reg, HDR_PAYLOAD_LEN_INC_PADDING);
                        /* HDR_TOTAL_LEN_OR_PAD_OFFSET is 0 */
                }
        }

        /* HDR_PAYLOAD_LEN_INC_PADDING is 0 */
        if (!endpoint->toward_ipa)
                val |= ipa_reg_encode(reg, HDR_PAD_TO_ALIGNMENT, pad_align);

        /* IPA v4.5 adds some most-significant bits to a few fields,
         * two of which are defined in the HDR (not HDR_EXT) register.
         */
        if (ipa->version >= IPA_VERSION_4_5) {
                /* HDR_TOTAL_LEN_OR_PAD_OFFSET is 0, so MSB is 0 */
                if (endpoint->config.qmap && !endpoint->toward_ipa) {
                        u32 mask = ipa_reg_field_max(reg, HDR_OFST_PKT_SIZE);
                        u32 off;     /* Field offset within header */

                        off = offsetof(struct rmnet_map_header, pkt_len);
                        /* Low bits are in the ENDP_INIT_HDR register */
                        off >>= hweight32(mask);
                        val |= ipa_reg_encode(reg, HDR_OFST_PKT_SIZE_MSB, off);
                        /* HDR_ADDITIONAL_CONST_LEN is 0 so MSB is 0 */
                }
        }

        iowrite32(val, ipa->reg_virt + ipa_reg_n_offset(reg, endpoint_id));
}

static void ipa_endpoint_init_hdr_metadata_mask(struct ipa_endpoint *endpoint)
{
        u32 endpoint_id = endpoint->endpoint_id;
        struct ipa *ipa = endpoint->ipa;
        const struct ipa_reg *reg;
        u32 val = 0;
        u32 offset;

        if (endpoint->toward_ipa)
                return;         /* Register not valid for TX endpoints */

        reg = ipa_reg(ipa,  ENDP_INIT_HDR_METADATA_MASK);
        offset = ipa_reg_n_offset(reg, endpoint_id);

        /* Note that HDR_ENDIANNESS indicates big endian header fields */
        if (endpoint->config.qmap)
                val = (__force u32)cpu_to_be32(IPA_ENDPOINT_QMAP_METADATA_MASK);

        iowrite32(val, ipa->reg_virt + offset);
}

static void ipa_endpoint_init_mode(struct ipa_endpoint *endpoint)
{
        struct ipa *ipa = endpoint->ipa;
        const struct ipa_reg *reg;
        u32 offset;
        u32 val;

        if (!endpoint->toward_ipa)
                return;         /* Register not valid for RX endpoints */

        reg = ipa_reg(ipa, ENDP_INIT_MODE);
        if (endpoint->config.dma_mode) {
                enum ipa_endpoint_name name = endpoint->config.dma_endpoint;
                u32 dma_endpoint_id = ipa->name_map[name]->endpoint_id;

                val = ipa_reg_encode(reg, ENDP_MODE, IPA_DMA);
                val |= ipa_reg_encode(reg, DEST_PIPE_INDEX, dma_endpoint_id);
        } else {
                val = ipa_reg_encode(reg, ENDP_MODE, IPA_BASIC);
        }
        /* All other bits unspecified (and 0) */

        offset = ipa_reg_n_offset(reg, endpoint->endpoint_id);
        iowrite32(val, ipa->reg_virt + offset);
}

/* For IPA v4.5+, times are expressed using Qtime.  The AP uses one of two
 * pulse generators (0 and 1) to measure elapsed time.  In ipa_qtime_config()
 * they're configured to have granularity 100 usec and 1 msec, respectively.
 *
 * The return value is the positive or negative Qtime value to use to
 * express the (microsecond) time provided.  A positive return value
 * means pulse generator 0 can be used; otherwise use pulse generator 1.
 */
static int ipa_qtime_val(u32 microseconds, u32 max)
{
        u32 val;

        /* Use 100 microsecond granularity if possible */
        val = DIV_ROUND_CLOSEST(microseconds, 100);
        if (val <= max)
                return (int)val;

        /* Have to use pulse generator 1 (millisecond granularity) */
        val = DIV_ROUND_CLOSEST(microseconds, 1000);
        WARN_ON(val > max);

        return (int)-val;
}

/* Encode the aggregation timer limit (microseconds) based on IPA version */
static u32 aggr_time_limit_encode(struct ipa *ipa, const struct ipa_reg *reg,
                                  u32 microseconds)
{
        u32 max;
        u32 val;

        if (!microseconds)
                return 0;       /* Nothing to compute if time limit is 0 */

        max = ipa_reg_field_max(reg, TIME_LIMIT);
        if (ipa->version >= IPA_VERSION_4_5) {
                u32 gran_sel;
                int ret;

                /* Compute the Qtime limit value to use */
                ret = ipa_qtime_val(microseconds, max);
                if (ret < 0) {
                        val = -ret;
                        gran_sel = ipa_reg_bit(reg, AGGR_GRAN_SEL);
                } else {
                        val = ret;
                        gran_sel = 0;
                }

                return gran_sel | ipa_reg_encode(reg, TIME_LIMIT, val);
        }

        /* We program aggregation granularity in ipa_hardware_config() */
        val = DIV_ROUND_CLOSEST(microseconds, IPA_AGGR_GRANULARITY);
        WARN(val > max, "aggr_time_limit too large (%u > %u usec)\n",
             microseconds, max * IPA_AGGR_GRANULARITY);

        return ipa_reg_encode(reg, TIME_LIMIT, val);
}

static void ipa_endpoint_init_aggr(struct ipa_endpoint *endpoint)
{
        u32 endpoint_id = endpoint->endpoint_id;
        struct ipa *ipa = endpoint->ipa;
        const struct ipa_reg *reg;
        u32 val = 0;

        reg = ipa_reg(ipa, ENDP_INIT_AGGR);
        if (endpoint->config.aggregation) {
                if (!endpoint->toward_ipa) {
                        const struct ipa_endpoint_rx *rx_config;
                        u32 buffer_size;
                        u32 limit;

                        rx_config = &endpoint->config.rx;
                        val |= ipa_reg_encode(reg, AGGR_EN, IPA_ENABLE_AGGR);
                        val |= ipa_reg_encode(reg, AGGR_TYPE, IPA_GENERIC);

                        buffer_size = rx_config->buffer_size;
                        limit = ipa_aggr_size_kb(buffer_size - NET_SKB_PAD,
                                                 rx_config->aggr_hard_limit);
                        val |= ipa_reg_encode(reg, BYTE_LIMIT, limit);

                        limit = rx_config->aggr_time_limit;
                        val |= aggr_time_limit_encode(ipa, reg, limit);

                        /* AGGR_PKT_LIMIT is 0 (unlimited) */

                        if (rx_config->aggr_close_eof)
                                val |= ipa_reg_bit(reg, SW_EOF_ACTIVE);
                } else {
                        val |= ipa_reg_encode(reg, AGGR_EN, IPA_ENABLE_DEAGGR);
                        val |= ipa_reg_encode(reg, AGGR_TYPE, IPA_QCMAP);
                        /* other fields ignored */
                }
                /* AGGR_FORCE_CLOSE is 0 */
                /* AGGR_GRAN_SEL is 0 for IPA v4.5 */
        } else {
                val |= ipa_reg_encode(reg, AGGR_EN, IPA_BYPASS_AGGR);
                /* other fields ignored */
        }

        iowrite32(val, ipa->reg_virt + ipa_reg_n_offset(reg, endpoint_id));
}

/* The head-of-line blocking timer is defined as a tick count.  For
 * IPA version 4.5 the tick count is based on the Qtimer, which is
 * derived from the 19.2 MHz SoC XO clock.  For older IPA versions
 * each tick represents 128 cycles of the IPA core clock.
 *
 * Return the encoded value representing the timeout period provided
 * that should be written to the ENDP_INIT_HOL_BLOCK_TIMER register.
 */
static u32 hol_block_timer_encode(struct ipa *ipa, const struct ipa_reg *reg,
                                  u32 microseconds)
{
        u32 width;
        u32 scale;
        u64 ticks;
        u64 rate;
        u32 high;
        u32 val;

        if (!microseconds)
                return 0;       /* Nothing to compute if timer period is 0 */

        if (ipa->version >= IPA_VERSION_4_5) {
                u32 max = ipa_reg_field_max(reg, TIMER_LIMIT);
                u32 gran_sel;
                int ret;

                /* Compute the Qtime limit value to use */
                ret = ipa_qtime_val(microseconds, max);
                if (ret < 0) {
                        val = -ret;
                        gran_sel = ipa_reg_bit(reg, TIMER_GRAN_SEL);
                } else {
                        val = ret;
                        gran_sel = 0;
                }

                return gran_sel | ipa_reg_encode(reg, TIMER_LIMIT, val);
        }

        /* Use 64 bit arithmetic to avoid overflow */
        rate = ipa_core_clock_rate(ipa);
        ticks = DIV_ROUND_CLOSEST(microseconds * rate, 128 * USEC_PER_SEC);

        /* We still need the result to fit into the field */
        WARN_ON(ticks > ipa_reg_field_max(reg, TIMER_BASE_VALUE));

        /* IPA v3.5.1 through v4.1 just record the tick count */
        if (ipa->version < IPA_VERSION_4_2)
                return ipa_reg_encode(reg, TIMER_BASE_VALUE, (u32)ticks);

        /* For IPA v4.2, the tick count is represented by base and
         * scale fields within the 32-bit timer register, where:
         *     ticks = base << scale;
         * The best precision is achieved when the base value is as
         * large as possible.  Find the highest set bit in the tick
         * count, and extract the number of bits in the base field
         * such that high bit is included.
         */
        high = fls(ticks);              /* 1..32 (or warning above) */
        width = hweight32(ipa_reg_fmask(reg, TIMER_BASE_VALUE));
        scale = high > width ? high - width : 0;
        if (scale) {
                /* If we're scaling, round up to get a closer result */
                ticks += 1 << (scale - 1);
                /* High bit was set, so rounding might have affected it */
                if (fls(ticks) != high)
                        scale++;
        }

        val = ipa_reg_encode(reg, TIMER_SCALE, scale);
        val |= ipa_reg_encode(reg, TIMER_BASE_VALUE, (u32)ticks >> scale);

        return val;
}

/* If microseconds is 0, timeout is immediate */
static void ipa_endpoint_init_hol_block_timer(struct ipa_endpoint *endpoint,
                                              u32 microseconds)
{
        u32 endpoint_id = endpoint->endpoint_id;
        struct ipa *ipa = endpoint->ipa;
        const struct ipa_reg *reg;
        u32 val;

        /* This should only be changed when HOL_BLOCK_EN is disabled */
        reg = ipa_reg(ipa, ENDP_INIT_HOL_BLOCK_TIMER);
        val = hol_block_timer_encode(ipa, reg, microseconds);

        iowrite32(val, ipa->reg_virt + ipa_reg_n_offset(reg, endpoint_id));
}

static void
ipa_endpoint_init_hol_block_en(struct ipa_endpoint *endpoint, bool enable)
{
        u32 endpoint_id = endpoint->endpoint_id;
        struct ipa *ipa = endpoint->ipa;
        const struct ipa_reg *reg;
        u32 offset;
        u32 val;

        reg = ipa_reg(ipa, ENDP_INIT_HOL_BLOCK_EN);
        offset = ipa_reg_n_offset(reg, endpoint_id);
        val = enable ? ipa_reg_bit(reg, HOL_BLOCK_EN) : 0;

        iowrite32(val, ipa->reg_virt + offset);

        /* When enabling, the register must be written twice for IPA v4.5+ */
        if (enable && ipa->version >= IPA_VERSION_4_5)
                iowrite32(val, ipa->reg_virt + offset);
}

/* Assumes HOL_BLOCK is in disabled state */
static void ipa_endpoint_init_hol_block_enable(struct ipa_endpoint *endpoint,
                                               u32 microseconds)
{
        ipa_endpoint_init_hol_block_timer(endpoint, microseconds);
        ipa_endpoint_init_hol_block_en(endpoint, true);
}

static void ipa_endpoint_init_hol_block_disable(struct ipa_endpoint *endpoint)
{
        ipa_endpoint_init_hol_block_en(endpoint, false);
}

void ipa_endpoint_modem_hol_block_clear_all(struct ipa *ipa)
{
        u32 endpoint_id = 0;

        while (endpoint_id < ipa->endpoint_count) {
                struct ipa_endpoint *endpoint = &ipa->endpoint[endpoint_id++];

                if (endpoint->toward_ipa || endpoint->ee_id != GSI_EE_MODEM)
                        continue;

                ipa_endpoint_init_hol_block_disable(endpoint);
                ipa_endpoint_init_hol_block_enable(endpoint, 0);
        }
}

static void ipa_endpoint_init_deaggr(struct ipa_endpoint *endpoint)
{
        u32 endpoint_id = endpoint->endpoint_id;
        struct ipa *ipa = endpoint->ipa;
        const struct ipa_reg *reg;
        u32 val = 0;

        if (!endpoint->toward_ipa)
                return;         /* Register not valid for RX endpoints */

        reg = ipa_reg(ipa, ENDP_INIT_DEAGGR);
        /* DEAGGR_HDR_LEN is 0 */
        /* PACKET_OFFSET_VALID is 0 */
        /* PACKET_OFFSET_LOCATION is ignored (not valid) */
        /* MAX_PACKET_LEN is 0 (not enforced) */

        iowrite32(val, ipa->reg_virt + ipa_reg_n_offset(reg, endpoint_id));
}

static void ipa_endpoint_init_rsrc_grp(struct ipa_endpoint *endpoint)
{
        u32 resource_group = endpoint->config.resource_group;
        u32 endpoint_id = endpoint->endpoint_id;
        struct ipa *ipa = endpoint->ipa;
        const struct ipa_reg *reg;
        u32 val;

        reg = ipa_reg(ipa, ENDP_INIT_RSRC_GRP);
        val = ipa_reg_encode(reg, ENDP_RSRC_GRP, resource_group);

        iowrite32(val, ipa->reg_virt + ipa_reg_n_offset(reg, endpoint_id));
}

static void ipa_endpoint_init_seq(struct ipa_endpoint *endpoint)
{
        u32 endpoint_id = endpoint->endpoint_id;
        struct ipa *ipa = endpoint->ipa;
        const struct ipa_reg *reg;
        u32 val;

        if (!endpoint->toward_ipa)
                return;         /* Register not valid for RX endpoints */

        reg = ipa_reg(ipa, ENDP_INIT_SEQ);

        /* Low-order byte configures primary packet processing */
        val = ipa_reg_encode(reg, SEQ_TYPE, endpoint->config.tx.seq_type);

        /* Second byte (if supported) configures replicated packet processing */
        if (ipa->version < IPA_VERSION_4_5)
                val |= ipa_reg_encode(reg, SEQ_REP_TYPE,
                                      endpoint->config.tx.seq_rep_type);

        iowrite32(val, ipa->reg_virt + ipa_reg_n_offset(reg, endpoint_id));
}

/**
 * ipa_endpoint_skb_tx() - Transmit a socket buffer
 * @endpoint:   Endpoint pointer
 * @skb:        Socket buffer to send
 *
 * Returns:     0 if successful, or a negative error code
 */
int ipa_endpoint_skb_tx(struct ipa_endpoint *endpoint, struct sk_buff *skb)
{
        struct gsi_trans *trans;
        u32 nr_frags;
        int ret;

        /* Make sure source endpoint's TLV FIFO has enough entries to
         * hold the linear portion of the skb and all its fragments.
         * If not, see if we can linearize it before giving up.
         */
        nr_frags = skb_shinfo(skb)->nr_frags;
        if (nr_frags > endpoint->skb_frag_max) {
                if (skb_linearize(skb))
                        return -E2BIG;
                nr_frags = 0;
        }

        trans = ipa_endpoint_trans_alloc(endpoint, 1 + nr_frags);
        if (!trans)
                return -EBUSY;

        ret = gsi_trans_skb_add(trans, skb);
        if (ret)
                goto err_trans_free;
        trans->data = skb;      /* transaction owns skb now */

        gsi_trans_commit(trans, !netdev_xmit_more());

        return 0;

err_trans_free:
        gsi_trans_free(trans);

        return -ENOMEM;
}

static void ipa_endpoint_status(struct ipa_endpoint *endpoint)
{
        u32 endpoint_id = endpoint->endpoint_id;
        struct ipa *ipa = endpoint->ipa;
        const struct ipa_reg *reg;
        u32 val = 0;

        reg = ipa_reg(ipa, ENDP_STATUS);
        if (endpoint->config.status_enable) {
                val |= ipa_reg_bit(reg, STATUS_EN);
                if (endpoint->toward_ipa) {
                        enum ipa_endpoint_name name;
                        u32 status_endpoint_id;

                        name = endpoint->config.tx.status_endpoint;
                        status_endpoint_id = ipa->name_map[name]->endpoint_id;

                        val |= ipa_reg_encode(reg, STATUS_ENDP,
                                              status_endpoint_id);
                }
                /* STATUS_LOCATION is 0, meaning status element precedes
                 * packet (not present for IPA v4.5+)
                 */
                /* STATUS_PKT_SUPPRESS_FMASK is 0 (not present for v4.0+) */
        }

        iowrite32(val, ipa->reg_virt + ipa_reg_n_offset(reg, endpoint_id));
}

static int ipa_endpoint_replenish_one(struct ipa_endpoint *endpoint,
                                      struct gsi_trans *trans)
{
        struct page *page;
        u32 buffer_size;
        u32 offset;
        u32 len;
        int ret;

        buffer_size = endpoint->config.rx.buffer_size;
        page = dev_alloc_pages(get_order(buffer_size));
        if (!page)
                return -ENOMEM;

        /* Offset the buffer to make space for skb headroom */
        offset = NET_SKB_PAD;
        len = buffer_size - offset;

        ret = gsi_trans_page_add(trans, page, len, offset);
        if (ret)
                put_page(page);
        else
                trans->data = page;     /* transaction owns page now */

        return ret;
}

/**
 * ipa_endpoint_replenish() - Replenish endpoint receive buffers
 * @endpoint:   Endpoint to be replenished
 *
 * The IPA hardware can hold a fixed number of receive buffers for an RX
 * endpoint, based on the number of entries in the underlying channel ring
 * buffer.  If an endpoint's "backlog" is non-zero, it indicates how many
 * more receive buffers can be supplied to the hardware.  Replenishing for
 * an endpoint can be disabled, in which case buffers are not queued to
 * the hardware.
 */
static void ipa_endpoint_replenish(struct ipa_endpoint *endpoint)
{
        struct gsi_trans *trans;

        if (!test_bit(IPA_REPLENISH_ENABLED, endpoint->replenish_flags))
                return;

        /* Skip it if it's already active */
        if (test_and_set_bit(IPA_REPLENISH_ACTIVE, endpoint->replenish_flags))
                return;

        while ((trans = ipa_endpoint_trans_alloc(endpoint, 1))) {
                bool doorbell;

                if (ipa_endpoint_replenish_one(endpoint, trans))
                        goto try_again_later;


                /* Ring the doorbell if we've got a full batch */
                doorbell = !(++endpoint->replenish_count % IPA_REPLENISH_BATCH);
                gsi_trans_commit(trans, doorbell);
        }

        clear_bit(IPA_REPLENISH_ACTIVE, endpoint->replenish_flags);

        return;

try_again_later:
        gsi_trans_free(trans);
        clear_bit(IPA_REPLENISH_ACTIVE, endpoint->replenish_flags);

        /* Whenever a receive buffer transaction completes we'll try to
         * replenish again.  It's unlikely, but if we fail to supply even
         * one buffer, nothing will trigger another replenish attempt.
         * If the hardware has no receive buffers queued, schedule work to
         * try replenishing again.
         */
        if (gsi_channel_trans_idle(&endpoint->ipa->gsi, endpoint->channel_id))
                schedule_delayed_work(&endpoint->replenish_work,
                                      msecs_to_jiffies(1));
}

static void ipa_endpoint_replenish_enable(struct ipa_endpoint *endpoint)
{
        set_bit(IPA_REPLENISH_ENABLED, endpoint->replenish_flags);

        /* Start replenishing if hardware currently has no buffers */
        if (gsi_channel_trans_idle(&endpoint->ipa->gsi, endpoint->channel_id))
                ipa_endpoint_replenish(endpoint);
}

static void ipa_endpoint_replenish_disable(struct ipa_endpoint *endpoint)
{
        clear_bit(IPA_REPLENISH_ENABLED, endpoint->replenish_flags);
}

static void ipa_endpoint_replenish_work(struct work_struct *work)
{
        struct delayed_work *dwork = to_delayed_work(work);
        struct ipa_endpoint *endpoint;

        endpoint = container_of(dwork, struct ipa_endpoint, replenish_work);

        ipa_endpoint_replenish(endpoint);
}

static void ipa_endpoint_skb_copy(struct ipa_endpoint *endpoint,
                                  void *data, u32 len, u32 extra)
{
        struct sk_buff *skb;

        if (!endpoint->netdev)
                return;

        skb = __dev_alloc_skb(len, GFP_ATOMIC);
        if (skb) {
                /* Copy the data into the socket buffer and receive it */
                skb_put(skb, len);
                memcpy(skb->data, data, len);
                skb->truesize += extra;
        }

        ipa_modem_skb_rx(endpoint->netdev, skb);
}

static bool ipa_endpoint_skb_build(struct ipa_endpoint *endpoint,
                                   struct page *page, u32 len)
{
        u32 buffer_size = endpoint->config.rx.buffer_size;
        struct sk_buff *skb;

        /* Nothing to do if there's no netdev */
        if (!endpoint->netdev)
                return false;

        WARN_ON(len > SKB_WITH_OVERHEAD(buffer_size - NET_SKB_PAD));

        skb = build_skb(page_address(page), buffer_size);
        if (skb) {
                /* Reserve the headroom and account for the data */
                skb_reserve(skb, NET_SKB_PAD);
                skb_put(skb, len);
        }

        /* Receive the buffer (or record drop if unable to build it) */
        ipa_modem_skb_rx(endpoint->netdev, skb);

        return skb != NULL;
}

/* The format of a packet status element is the same for several status
 * types (opcodes).  Other types aren't currently supported.
 */
static bool ipa_status_format_packet(enum ipa_status_opcode opcode)
{
        switch (opcode) {
        case IPA_STATUS_OPCODE_PACKET:
        case IPA_STATUS_OPCODE_DROPPED_PACKET:
        case IPA_STATUS_OPCODE_SUSPENDED_PACKET:
        case IPA_STATUS_OPCODE_PACKET_2ND_PASS:
                return true;
        default:
                return false;
        }
}

static bool ipa_endpoint_status_skip(struct ipa_endpoint *endpoint,
                                     const struct ipa_status *status)
{
        u32 endpoint_id;

        if (!ipa_status_format_packet(status->opcode))
                return true;
        if (!status->pkt_len)
                return true;
        endpoint_id = u8_get_bits(status->endp_dst_idx,
                                  IPA_STATUS_DST_IDX_FMASK);
        if (endpoint_id != endpoint->endpoint_id)
                return true;

        return false;   /* Don't skip this packet, process it */
}

static bool ipa_endpoint_status_tag(struct ipa_endpoint *endpoint,
                                    const struct ipa_status *status)
{
        struct ipa_endpoint *command_endpoint;
        struct ipa *ipa = endpoint->ipa;
        u32 endpoint_id;

        if (!le16_get_bits(status->mask, IPA_STATUS_MASK_TAG_VALID_FMASK))
                return false;   /* No valid tag */

        /* The status contains a valid tag.  We know the packet was sent to
         * this endpoint (already verified by ipa_endpoint_status_skip()).
         * If the packet came from the AP->command TX endpoint we know
         * this packet was sent as part of the pipeline clear process.
         */
        endpoint_id = u8_get_bits(status->endp_src_idx,
                                  IPA_STATUS_SRC_IDX_FMASK);
        command_endpoint = ipa->name_map[IPA_ENDPOINT_AP_COMMAND_TX];
        if (endpoint_id == command_endpoint->endpoint_id) {
                complete(&ipa->completion);
        } else {
                dev_err(&ipa->pdev->dev,
                        "unexpected tagged packet from endpoint %u\n",
                        endpoint_id);
        }

        return true;
}

/* Return whether the status indicates the packet should be dropped */
static bool ipa_endpoint_status_drop(struct ipa_endpoint *endpoint,
                                     const struct ipa_status *status)
{
        u32 val;

        /* If the status indicates a tagged transfer, we'll drop the packet */
        if (ipa_endpoint_status_tag(endpoint, status))
                return true;

        /* Deaggregation exceptions we drop; all other types we consume */
        if (status->exception)
                return status->exception == IPA_STATUS_EXCEPTION_DEAGGR;

        /* Drop the packet if it fails to match a routing rule; otherwise no */
        val = le32_get_bits(status->flags1, IPA_STATUS_FLAGS1_RT_RULE_ID_FMASK);

        return val == field_max(IPA_STATUS_FLAGS1_RT_RULE_ID_FMASK);
}

static void ipa_endpoint_status_parse(struct ipa_endpoint *endpoint,
                                      struct page *page, u32 total_len)
{
        u32 buffer_size = endpoint->config.rx.buffer_size;
        void *data = page_address(page) + NET_SKB_PAD;
        u32 unused = buffer_size - total_len;
        u32 resid = total_len;

        while (resid) {
                const struct ipa_status *status = data;
                u32 align;
                u32 len;

                if (resid < sizeof(*status)) {
                        dev_err(&endpoint->ipa->pdev->dev,
                                "short message (%u bytes < %zu byte status)\n",
                                resid, sizeof(*status));
                        break;
                }

                /* Skip over status packets that lack packet data */
                if (ipa_endpoint_status_skip(endpoint, status)) {
                        data += sizeof(*status);
                        resid -= sizeof(*status);
                        continue;
                }

                /* Compute the amount of buffer space consumed by the packet,
                 * including the status element.  If the hardware is configured
                 * to pad packet data to an aligned boundary, account for that.
                 * And if checksum offload is enabled a trailer containing
                 * computed checksum information will be appended.
                 */
                align = endpoint->config.rx.pad_align ? : 1;
                len = le16_to_cpu(status->pkt_len);
                len = sizeof(*status) + ALIGN(len, align);
                if (endpoint->config.checksum)
                        len += sizeof(struct rmnet_map_dl_csum_trailer);

                if (!ipa_endpoint_status_drop(endpoint, status)) {
                        void *data2;
                        u32 extra;
                        u32 len2;

                        /* Client receives only packet data (no status) */
                        data2 = data + sizeof(*status);
                        len2 = le16_to_cpu(status->pkt_len);

                        /* Have the true size reflect the extra unused space in
                         * the original receive buffer.  Distribute the "cost"
                         * proportionately across all aggregated packets in the
                         * buffer.
                         */
                        extra = DIV_ROUND_CLOSEST(unused * len, total_len);
                        ipa_endpoint_skb_copy(endpoint, data2, len2, extra);
                }

                /* Consume status and the full packet it describes */
                data += len;
                resid -= len;
        }
}

void ipa_endpoint_trans_complete(struct ipa_endpoint *endpoint,
                                 struct gsi_trans *trans)
{
        struct page *page;

        if (endpoint->toward_ipa)
                return;

        if (trans->cancelled)
                goto done;

        /* Parse or build a socket buffer using the actual received length */
        page = trans->data;
        if (endpoint->config.status_enable)
                ipa_endpoint_status_parse(endpoint, page, trans->len);
        else if (ipa_endpoint_skb_build(endpoint, page, trans->len))
                trans->data = NULL;     /* Pages have been consumed */
done:
        ipa_endpoint_replenish(endpoint);
}

void ipa_endpoint_trans_release(struct ipa_endpoint *endpoint,
                                struct gsi_trans *trans)
{
        if (endpoint->toward_ipa) {
                struct ipa *ipa = endpoint->ipa;

                /* Nothing to do for command transactions */
                if (endpoint != ipa->name_map[IPA_ENDPOINT_AP_COMMAND_TX]) {
                        struct sk_buff *skb = trans->data;

                        if (skb)
                                dev_kfree_skb_any(skb);
                }
        } else {
                struct page *page = trans->data;

                if (page)
                        put_page(page);
        }
}

void ipa_endpoint_default_route_set(struct ipa *ipa, u32 endpoint_id)
{
        const struct ipa_reg *reg;
        u32 val;

        reg = ipa_reg(ipa, ROUTE);
        /* ROUTE_DIS is 0 */
        val = ipa_reg_encode(reg, ROUTE_DEF_PIPE, endpoint_id);
        val |= ipa_reg_bit(reg, ROUTE_DEF_HDR_TABLE);
        /* ROUTE_DEF_HDR_OFST is 0 */
        val |= ipa_reg_encode(reg, ROUTE_FRAG_DEF_PIPE, endpoint_id);
        val |= ipa_reg_bit(reg, ROUTE_DEF_RETAIN_HDR);

        iowrite32(val, ipa->reg_virt + ipa_reg_offset(reg));
}

void ipa_endpoint_default_route_clear(struct ipa *ipa)
{
        ipa_endpoint_default_route_set(ipa, 0);
}

/**
 * ipa_endpoint_reset_rx_aggr() - Reset RX endpoint with aggregation active
 * @endpoint:   Endpoint to be reset
 *
 * If aggregation is active on an RX endpoint when a reset is performed
 * on its underlying GSI channel, a special sequence of actions must be
 * taken to ensure the IPA pipeline is properly cleared.
 *
 * Return:      0 if successful, or a negative error code
 */
static int ipa_endpoint_reset_rx_aggr(struct ipa_endpoint *endpoint)
{
        struct device *dev = &endpoint->ipa->pdev->dev;
        struct ipa *ipa = endpoint->ipa;
        struct gsi *gsi = &ipa->gsi;
        bool suspended = false;
        dma_addr_t addr;
        u32 retries;
        u32 len = 1;
        void *virt;
        int ret;

        virt = kzalloc(len, GFP_KERNEL);
        if (!virt)
                return -ENOMEM;

        addr = dma_map_single(dev, virt, len, DMA_FROM_DEVICE);
        if (dma_mapping_error(dev, addr)) {
                ret = -ENOMEM;
                goto out_kfree;
        }

        /* Force close aggregation before issuing the reset */
        ipa_endpoint_force_close(endpoint);

        /* Reset and reconfigure the channel with the doorbell engine
         * disabled.  Then poll until we know aggregation is no longer
         * active.  We'll re-enable the doorbell (if appropriate) when
         * we reset again below.
         */
        gsi_channel_reset(gsi, endpoint->channel_id, false);

        /* Make sure the channel isn't suspended */
        suspended = ipa_endpoint_program_suspend(endpoint, false);

        /* Start channel and do a 1 byte read */
        ret = gsi_channel_start(gsi, endpoint->channel_id);
        if (ret)
                goto out_suspend_again;

        ret = gsi_trans_read_byte(gsi, endpoint->channel_id, addr);
        if (ret)
                goto err_endpoint_stop;

        /* Wait for aggregation to be closed on the channel */
        retries = IPA_ENDPOINT_RESET_AGGR_RETRY_MAX;
        do {
                if (!ipa_endpoint_aggr_active(endpoint))
                        break;
                usleep_range(USEC_PER_MSEC, 2 * USEC_PER_MSEC);
        } while (retries--);

        /* Check one last time */
        if (ipa_endpoint_aggr_active(endpoint))
                dev_err(dev, "endpoint %u still active during reset\n",
                        endpoint->endpoint_id);

        gsi_trans_read_byte_done(gsi, endpoint->channel_id);

        ret = gsi_channel_stop(gsi, endpoint->channel_id);
        if (ret)
                goto out_suspend_again;

        /* Finally, reset and reconfigure the channel again (re-enabling
         * the doorbell engine if appropriate).  Sleep for 1 millisecond to
         * complete the channel reset sequence.  Finish by suspending the
         * channel again (if necessary).
         */
        gsi_channel_reset(gsi, endpoint->channel_id, true);

        usleep_range(USEC_PER_MSEC, 2 * USEC_PER_MSEC);

        goto out_suspend_again;

err_endpoint_stop:
        (void)gsi_channel_stop(gsi, endpoint->channel_id);
out_suspend_again:
        if (suspended)
                (void)ipa_endpoint_program_suspend(endpoint, true);
        dma_unmap_single(dev, addr, len, DMA_FROM_DEVICE);
out_kfree:
        kfree(virt);

        return ret;
}

static void ipa_endpoint_reset(struct ipa_endpoint *endpoint)
{
        u32 channel_id = endpoint->channel_id;
        struct ipa *ipa = endpoint->ipa;
        bool special;
        int ret = 0;

        /* On IPA v3.5.1, if an RX endpoint is reset while aggregation
         * is active, we need to handle things specially to recover.
         * All other cases just need to reset the underlying GSI channel.
         */
        special = ipa->version < IPA_VERSION_4_0 && !endpoint->toward_ipa &&
                        endpoint->config.aggregation;
        if (special && ipa_endpoint_aggr_active(endpoint))
                ret = ipa_endpoint_reset_rx_aggr(endpoint);
        else
                gsi_channel_reset(&ipa->gsi, channel_id, true);

        if (ret)
                dev_err(&ipa->pdev->dev,
                        "error %d resetting channel %u for endpoint %u\n",
                        ret, endpoint->channel_id, endpoint->endpoint_id);
}

static void ipa_endpoint_program(struct ipa_endpoint *endpoint)
{
        if (endpoint->toward_ipa) {
                /* Newer versions of IPA use GSI channel flow control
                 * instead of endpoint DELAY mode to prevent sending data.
                 * Flow control is disabled for newly-allocated channels,
                 * and we can assume flow control is not (ever) enabled
                 * for AP TX channels.
                 */
                if (endpoint->ipa->version < IPA_VERSION_4_2)
                        ipa_endpoint_program_delay(endpoint, false);
        } else {
                /* Ensure suspend mode is off on all AP RX endpoints */
                (void)ipa_endpoint_program_suspend(endpoint, false);
        }
        ipa_endpoint_init_cfg(endpoint);
        ipa_endpoint_init_nat(endpoint);
        ipa_endpoint_init_hdr(endpoint);
        ipa_endpoint_init_hdr_ext(endpoint);
        ipa_endpoint_init_hdr_metadata_mask(endpoint);
        ipa_endpoint_init_mode(endpoint);
        ipa_endpoint_init_aggr(endpoint);
        if (!endpoint->toward_ipa) {
                if (endpoint->config.rx.holb_drop)
                        ipa_endpoint_init_hol_block_enable(endpoint, 0);
                else
                        ipa_endpoint_init_hol_block_disable(endpoint);
        }
        ipa_endpoint_init_deaggr(endpoint);
        ipa_endpoint_init_rsrc_grp(endpoint);
        ipa_endpoint_init_seq(endpoint);
        ipa_endpoint_status(endpoint);
}

int ipa_endpoint_enable_one(struct ipa_endpoint *endpoint)
{
        u32 endpoint_id = endpoint->endpoint_id;
        struct ipa *ipa = endpoint->ipa;
        struct gsi *gsi = &ipa->gsi;
        int ret;

        ret = gsi_channel_start(gsi, endpoint->channel_id);
        if (ret) {
                dev_err(&ipa->pdev->dev,
                        "error %d starting %cX channel %u for endpoint %u\n",
                        ret, endpoint->toward_ipa ? 'T' : 'R',
                        endpoint->channel_id, endpoint_id);
                return ret;
        }

        if (!endpoint->toward_ipa) {
                ipa_interrupt_suspend_enable(ipa->interrupt, endpoint_id);
                ipa_endpoint_replenish_enable(endpoint);
        }

        __set_bit(endpoint_id, ipa->enabled);

        return 0;
}

void ipa_endpoint_disable_one(struct ipa_endpoint *endpoint)
{
        u32 endpoint_id = endpoint->endpoint_id;
        struct ipa *ipa = endpoint->ipa;
        struct gsi *gsi = &ipa->gsi;
        int ret;

        if (!test_bit(endpoint_id, ipa->enabled))
                return;

        __clear_bit(endpoint_id, endpoint->ipa->enabled);

        if (!endpoint->toward_ipa) {
                ipa_endpoint_replenish_disable(endpoint);
                ipa_interrupt_suspend_disable(ipa->interrupt, endpoint_id);
        }

        /* Note that if stop fails, the channel's state is not well-defined */
        ret = gsi_channel_stop(gsi, endpoint->channel_id);
        if (ret)
                dev_err(&ipa->pdev->dev,
                        "error %d attempting to stop endpoint %u\n", ret,
                        endpoint_id);
}

void ipa_endpoint_suspend_one(struct ipa_endpoint *endpoint)
{
        struct device *dev = &endpoint->ipa->pdev->dev;
        struct gsi *gsi = &endpoint->ipa->gsi;
        int ret;

        if (!test_bit(endpoint->endpoint_id, endpoint->ipa->enabled))
                return;

        if (!endpoint->toward_ipa) {
                ipa_endpoint_replenish_disable(endpoint);
                (void)ipa_endpoint_program_suspend(endpoint, true);
        }

        ret = gsi_channel_suspend(gsi, endpoint->channel_id);
        if (ret)
                dev_err(dev, "error %d suspending channel %u\n", ret,
                        endpoint->channel_id);
}

void ipa_endpoint_resume_one(struct ipa_endpoint *endpoint)
{
        struct device *dev = &endpoint->ipa->pdev->dev;
        struct gsi *gsi = &endpoint->ipa->gsi;
        int ret;

        if (!test_bit(endpoint->endpoint_id, endpoint->ipa->enabled))
                return;

        if (!endpoint->toward_ipa)
                (void)ipa_endpoint_program_suspend(endpoint, false);

        ret = gsi_channel_resume(gsi, endpoint->channel_id);
        if (ret)
                dev_err(dev, "error %d resuming channel %u\n", ret,
                        endpoint->channel_id);
        else if (!endpoint->toward_ipa)
                ipa_endpoint_replenish_enable(endpoint);
}

void ipa_endpoint_suspend(struct ipa *ipa)
{
        if (!ipa->setup_complete)
                return;

        if (ipa->modem_netdev)
                ipa_modem_suspend(ipa->modem_netdev);

        ipa_endpoint_suspend_one(ipa->name_map[IPA_ENDPOINT_AP_LAN_RX]);
        ipa_endpoint_suspend_one(ipa->name_map[IPA_ENDPOINT_AP_COMMAND_TX]);
}

void ipa_endpoint_resume(struct ipa *ipa)
{
        if (!ipa->setup_complete)
                return;

        ipa_endpoint_resume_one(ipa->name_map[IPA_ENDPOINT_AP_COMMAND_TX]);
        ipa_endpoint_resume_one(ipa->name_map[IPA_ENDPOINT_AP_LAN_RX]);

        if (ipa->modem_netdev)
                ipa_modem_resume(ipa->modem_netdev);
}

static void ipa_endpoint_setup_one(struct ipa_endpoint *endpoint)
{
        struct gsi *gsi = &endpoint->ipa->gsi;
        u32 channel_id = endpoint->channel_id;

        /* Only AP endpoints get set up */
        if (endpoint->ee_id != GSI_EE_AP)
                return;

        endpoint->skb_frag_max = gsi->channel[channel_id].trans_tre_max - 1;
        if (!endpoint->toward_ipa) {
                /* RX transactions require a single TRE, so the maximum
                 * backlog is the same as the maximum outstanding TREs.
                 */
                clear_bit(IPA_REPLENISH_ENABLED, endpoint->replenish_flags);
                clear_bit(IPA_REPLENISH_ACTIVE, endpoint->replenish_flags);
                INIT_DELAYED_WORK(&endpoint->replenish_work,
                                  ipa_endpoint_replenish_work);
        }

        ipa_endpoint_program(endpoint);

        __set_bit(endpoint->endpoint_id, endpoint->ipa->set_up);
}

static void ipa_endpoint_teardown_one(struct ipa_endpoint *endpoint)
{
        __clear_bit(endpoint->endpoint_id, endpoint->ipa->set_up);

        if (!endpoint->toward_ipa)
                cancel_delayed_work_sync(&endpoint->replenish_work);

        ipa_endpoint_reset(endpoint);
}

void ipa_endpoint_setup(struct ipa *ipa)
{
        u32 endpoint_id;

        for_each_set_bit(endpoint_id, ipa->defined, ipa->endpoint_count)
                ipa_endpoint_setup_one(&ipa->endpoint[endpoint_id]);
}

void ipa_endpoint_teardown(struct ipa *ipa)
{
        u32 endpoint_id;

        for_each_set_bit(endpoint_id, ipa->set_up, ipa->endpoint_count)
                ipa_endpoint_teardown_one(&ipa->endpoint[endpoint_id]);
}

void ipa_endpoint_deconfig(struct ipa *ipa)
{
        ipa->available_count = 0;
        bitmap_free(ipa->available);
        ipa->available = NULL;
}

int ipa_endpoint_config(struct ipa *ipa)
{
        struct device *dev = &ipa->pdev->dev;
        const struct ipa_reg *reg;
        u32 endpoint_id;
        u32 tx_count;
        u32 rx_count;
        u32 rx_base;
        u32 limit;
        u32 val;

        /* Prior to IPA v3.5, the FLAVOR_0 register was not supported.
         * Furthermore, the endpoints were not grouped such that TX
         * endpoint numbers started with 0 and RX endpoints had numbers
         * higher than all TX endpoints, so we can't do the simple
         * direction check used for newer hardware below.
         *
         * For hardware that doesn't support the FLAVOR_0 register,
         * just set the available mask to support any endpoint, and
         * assume the configuration is valid.
         */
        if (ipa->version < IPA_VERSION_3_5) {
                ipa->available = bitmap_zalloc(IPA_ENDPOINT_MAX, GFP_KERNEL);
                if (!ipa->available)
                        return -ENOMEM;
                ipa->available_count = IPA_ENDPOINT_MAX;

                bitmap_set(ipa->available, 0, IPA_ENDPOINT_MAX);

                return 0;
        }

        /* Find out about the endpoints supplied by the hardware, and ensure
         * the highest one doesn't exceed the number supported by software.
         */
        reg = ipa_reg(ipa, FLAVOR_0);
        val = ioread32(ipa->reg_virt + ipa_reg_offset(reg));

        /* Our RX is an IPA producer; our TX is an IPA consumer. */
        tx_count = ipa_reg_decode(reg, MAX_CONS_PIPES, val);
        rx_count = ipa_reg_decode(reg, MAX_PROD_PIPES, val);
        rx_base = ipa_reg_decode(reg, PROD_LOWEST, val);

        limit = rx_base + rx_count;
        if (limit > IPA_ENDPOINT_MAX) {
                dev_err(dev, "too many endpoints, %u > %u\n",
                        limit, IPA_ENDPOINT_MAX);
                return -EINVAL;
        }

        /* Allocate and initialize the available endpoint bitmap */
        ipa->available = bitmap_zalloc(limit, GFP_KERNEL);
        if (!ipa->available)
                return -ENOMEM;
        ipa->available_count = limit;

        /* Mark all supported RX and TX endpoints as available */
        bitmap_set(ipa->available, 0, tx_count);
        bitmap_set(ipa->available, rx_base, rx_count);

        for_each_set_bit(endpoint_id, ipa->defined, ipa->endpoint_count) {
                struct ipa_endpoint *endpoint;

                if (endpoint_id >= limit) {
                        dev_err(dev, "invalid endpoint id, %u > %u\n",
                                endpoint_id, limit - 1);
                        goto err_free_bitmap;
                }

                if (!test_bit(endpoint_id, ipa->available)) {
                        dev_err(dev, "unavailable endpoint id %u\n",
                                endpoint_id);
                        goto err_free_bitmap;
                }

                /* Make sure it's pointing in the right direction */
                endpoint = &ipa->endpoint[endpoint_id];
                if (endpoint->toward_ipa) {
                        if (endpoint_id < tx_count)
                                continue;
                } else if (endpoint_id >= rx_base) {
                        continue;
                }

                dev_err(dev, "endpoint id %u wrong direction\n", endpoint_id);
                goto err_free_bitmap;
        }

        return 0;

err_free_bitmap:
        ipa_endpoint_deconfig(ipa);

        return -EINVAL;
}

static void ipa_endpoint_init_one(struct ipa *ipa, enum ipa_endpoint_name name,
                                  const struct ipa_gsi_endpoint_data *data)
{
        struct ipa_endpoint *endpoint;

        endpoint = &ipa->endpoint[data->endpoint_id];

        if (data->ee_id == GSI_EE_AP)
                ipa->channel_map[data->channel_id] = endpoint;
        ipa->name_map[name] = endpoint;

        endpoint->ipa = ipa;
        endpoint->ee_id = data->ee_id;
        endpoint->channel_id = data->channel_id;
        endpoint->endpoint_id = data->endpoint_id;
        endpoint->toward_ipa = data->toward_ipa;
        endpoint->config = data->endpoint.config;

        __set_bit(endpoint->endpoint_id, ipa->defined);
}

static void ipa_endpoint_exit_one(struct ipa_endpoint *endpoint)
{
        __clear_bit(endpoint->endpoint_id, endpoint->ipa->defined);

        memset(endpoint, 0, sizeof(*endpoint));
}

void ipa_endpoint_exit(struct ipa *ipa)
{
        u32 endpoint_id;

        ipa->filtered = 0;

        for_each_set_bit(endpoint_id, ipa->defined, ipa->endpoint_count)
                ipa_endpoint_exit_one(&ipa->endpoint[endpoint_id]);

        bitmap_free(ipa->enabled);
        ipa->enabled = NULL;
        bitmap_free(ipa->set_up);
        ipa->set_up = NULL;
        bitmap_free(ipa->defined);
        ipa->defined = NULL;

        memset(ipa->name_map, 0, sizeof(ipa->name_map));
        memset(ipa->channel_map, 0, sizeof(ipa->channel_map));
}

/* Returns a bitmask of endpoints that support filtering, or 0 on error */
int ipa_endpoint_init(struct ipa *ipa, u32 count,
                      const struct ipa_gsi_endpoint_data *data)
{
        enum ipa_endpoint_name name;
        u32 filtered;

        BUILD_BUG_ON(!IPA_REPLENISH_BATCH);

        /* Number of endpoints is one more than the maximum ID */
        ipa->endpoint_count = ipa_endpoint_max(ipa, count, data) + 1;
        if (!ipa->endpoint_count)
                return -EINVAL;

        /* Initialize endpoint state bitmaps */
        ipa->defined = bitmap_zalloc(ipa->endpoint_count, GFP_KERNEL);
        if (!ipa->defined)
                return -ENOMEM;

        ipa->set_up = bitmap_zalloc(ipa->endpoint_count, GFP_KERNEL);
        if (!ipa->set_up)
                goto err_free_defined;

        ipa->enabled = bitmap_zalloc(ipa->endpoint_count, GFP_KERNEL);
        if (!ipa->enabled)
                goto err_free_set_up;

        filtered = 0;
        for (name = 0; name < count; name++, data++) {
                if (ipa_gsi_endpoint_data_empty(data))
                        continue;       /* Skip over empty slots */

                ipa_endpoint_init_one(ipa, name, data);

                if (data->endpoint.filter_support)
                        filtered |= BIT(data->endpoint_id);
                if (data->ee_id == GSI_EE_MODEM && data->toward_ipa)
                        ipa->modem_tx_count++;
        }

        /* Make sure the set of filtered endpoints is valid */
        if (!ipa_filtered_valid(ipa, filtered)) {
                ipa_endpoint_exit(ipa);

                return -EINVAL;
        }

        ipa->filtered = filtered;

        return 0;

err_free_set_up:
        bitmap_free(ipa->set_up);
        ipa->set_up = NULL;
err_free_defined:
        bitmap_free(ipa->defined);
        ipa->defined = NULL;

        return -ENOMEM;
}