+++ /dev/null
-// SPDX-License-Identifier: GPL-2.0-only OR MIT
-/*
- * Apple mailbox driver
- *
- * Copyright (C) 2021 The Asahi Linux Contributors
- *
- * This driver adds support for two mailbox variants (called ASC and M3 by
- * Apple) found in Apple SoCs such as the M1. It consists of two FIFOs used to
- * exchange 64+32 bit messages between the main CPU and a co-processor.
- * Various coprocessors implement different IPC protocols based on these simple
- * messages and shared memory buffers.
- *
- * Both the main CPU and the co-processor see the same set of registers but
- * the first FIFO (A2I) is always used to transfer messages from the application
- * processor (us) to the I/O processor and the second one (I2A) for the
- * other direction.
- */
-
-#include <linux/apple-mailbox.h>
-#include <linux/delay.h>
-#include <linux/device.h>
-#include <linux/gfp.h>
-#include <linux/interrupt.h>
-#include <linux/io.h>
-#include <linux/mailbox_controller.h>
-#include <linux/module.h>
-#include <linux/of.h>
-#include <linux/platform_device.h>
-#include <linux/spinlock.h>
-#include <linux/types.h>
-
-#define APPLE_ASC_MBOX_CONTROL_FULL BIT(16)
-#define APPLE_ASC_MBOX_CONTROL_EMPTY BIT(17)
-
-#define APPLE_ASC_MBOX_A2I_CONTROL 0x110
-#define APPLE_ASC_MBOX_A2I_SEND0 0x800
-#define APPLE_ASC_MBOX_A2I_SEND1 0x808
-#define APPLE_ASC_MBOX_A2I_RECV0 0x810
-#define APPLE_ASC_MBOX_A2I_RECV1 0x818
-
-#define APPLE_ASC_MBOX_I2A_CONTROL 0x114
-#define APPLE_ASC_MBOX_I2A_SEND0 0x820
-#define APPLE_ASC_MBOX_I2A_SEND1 0x828
-#define APPLE_ASC_MBOX_I2A_RECV0 0x830
-#define APPLE_ASC_MBOX_I2A_RECV1 0x838
-
-#define APPLE_M3_MBOX_CONTROL_FULL BIT(16)
-#define APPLE_M3_MBOX_CONTROL_EMPTY BIT(17)
-
-#define APPLE_M3_MBOX_A2I_CONTROL 0x50
-#define APPLE_M3_MBOX_A2I_SEND0 0x60
-#define APPLE_M3_MBOX_A2I_SEND1 0x68
-#define APPLE_M3_MBOX_A2I_RECV0 0x70
-#define APPLE_M3_MBOX_A2I_RECV1 0x78
-
-#define APPLE_M3_MBOX_I2A_CONTROL 0x80
-#define APPLE_M3_MBOX_I2A_SEND0 0x90
-#define APPLE_M3_MBOX_I2A_SEND1 0x98
-#define APPLE_M3_MBOX_I2A_RECV0 0xa0
-#define APPLE_M3_MBOX_I2A_RECV1 0xa8
-
-#define APPLE_M3_MBOX_IRQ_ENABLE 0x48
-#define APPLE_M3_MBOX_IRQ_ACK 0x4c
-#define APPLE_M3_MBOX_IRQ_A2I_EMPTY BIT(0)
-#define APPLE_M3_MBOX_IRQ_A2I_NOT_EMPTY BIT(1)
-#define APPLE_M3_MBOX_IRQ_I2A_EMPTY BIT(2)
-#define APPLE_M3_MBOX_IRQ_I2A_NOT_EMPTY BIT(3)
-
-#define APPLE_MBOX_MSG1_OUTCNT GENMASK(56, 52)
-#define APPLE_MBOX_MSG1_INCNT GENMASK(51, 48)
-#define APPLE_MBOX_MSG1_OUTPTR GENMASK(47, 44)
-#define APPLE_MBOX_MSG1_INPTR GENMASK(43, 40)
-#define APPLE_MBOX_MSG1_MSG GENMASK(31, 0)
-
-struct apple_mbox_hw {
- unsigned int control_full;
- unsigned int control_empty;
-
- unsigned int a2i_control;
- unsigned int a2i_send0;
- unsigned int a2i_send1;
-
- unsigned int i2a_control;
- unsigned int i2a_recv0;
- unsigned int i2a_recv1;
-
- bool has_irq_controls;
- unsigned int irq_enable;
- unsigned int irq_ack;
- unsigned int irq_bit_recv_not_empty;
- unsigned int irq_bit_send_empty;
-};
-
-struct apple_mbox {
- void __iomem *regs;
- const struct apple_mbox_hw *hw;
-
- int irq_recv_not_empty;
- int irq_send_empty;
-
- struct mbox_chan chan;
-
- struct device *dev;
- struct mbox_controller controller;
- spinlock_t rx_lock;
-};
-
-static const struct of_device_id apple_mbox_of_match[];
-
-static bool apple_mbox_hw_can_send(struct apple_mbox *apple_mbox)
-{
- u32 mbox_ctrl =
- readl_relaxed(apple_mbox->regs + apple_mbox->hw->a2i_control);
-
- return !(mbox_ctrl & apple_mbox->hw->control_full);
-}
-
-static bool apple_mbox_hw_send_empty(struct apple_mbox *apple_mbox)
-{
- u32 mbox_ctrl =
- readl_relaxed(apple_mbox->regs + apple_mbox->hw->a2i_control);
-
- return mbox_ctrl & apple_mbox->hw->control_empty;
-}
-
-static int apple_mbox_hw_send(struct apple_mbox *apple_mbox,
- struct apple_mbox_msg *msg)
-{
- if (!apple_mbox_hw_can_send(apple_mbox))
- return -EBUSY;
-
- dev_dbg(apple_mbox->dev, "> TX %016llx %08x\n", msg->msg0, msg->msg1);
-
- writeq_relaxed(msg->msg0, apple_mbox->regs + apple_mbox->hw->a2i_send0);
- writeq_relaxed(FIELD_PREP(APPLE_MBOX_MSG1_MSG, msg->msg1),
- apple_mbox->regs + apple_mbox->hw->a2i_send1);
-
- return 0;
-}
-
-static bool apple_mbox_hw_can_recv(struct apple_mbox *apple_mbox)
-{
- u32 mbox_ctrl =
- readl_relaxed(apple_mbox->regs + apple_mbox->hw->i2a_control);
-
- return !(mbox_ctrl & apple_mbox->hw->control_empty);
-}
-
-static int apple_mbox_hw_recv(struct apple_mbox *apple_mbox,
- struct apple_mbox_msg *msg)
-{
- if (!apple_mbox_hw_can_recv(apple_mbox))
- return -ENOMSG;
-
- msg->msg0 = readq_relaxed(apple_mbox->regs + apple_mbox->hw->i2a_recv0);
- msg->msg1 = FIELD_GET(
- APPLE_MBOX_MSG1_MSG,
- readq_relaxed(apple_mbox->regs + apple_mbox->hw->i2a_recv1));
-
- dev_dbg(apple_mbox->dev, "< RX %016llx %08x\n", msg->msg0, msg->msg1);
-
- return 0;
-}
-
-static int apple_mbox_chan_send_data(struct mbox_chan *chan, void *data)
-{
- struct apple_mbox *apple_mbox = chan->con_priv;
- struct apple_mbox_msg *msg = data;
- int ret;
-
- ret = apple_mbox_hw_send(apple_mbox, msg);
- if (ret)
- return ret;
-
- /*
- * The interrupt is level triggered and will keep firing as long as the
- * FIFO is empty. It will also keep firing if the FIFO was empty
- * at any point in the past until it has been acknowledged at the
- * mailbox level. By acknowledging it here we can ensure that we will
- * only get the interrupt once the FIFO has been cleared again.
- * If the FIFO is already empty before the ack it will fire again
- * immediately after the ack.
- */
- if (apple_mbox->hw->has_irq_controls) {
- writel_relaxed(apple_mbox->hw->irq_bit_send_empty,
- apple_mbox->regs + apple_mbox->hw->irq_ack);
- }
- enable_irq(apple_mbox->irq_send_empty);
-
- return 0;
-}
-
-static irqreturn_t apple_mbox_send_empty_irq(int irq, void *data)
-{
- struct apple_mbox *apple_mbox = data;
-
- /*
- * We don't need to acknowledge the interrupt at the mailbox level
- * here even if supported by the hardware. It will keep firing but that
- * doesn't matter since it's disabled at the main interrupt controller.
- * apple_mbox_chan_send_data will acknowledge it before enabling
- * it at the main controller again.
- */
- disable_irq_nosync(apple_mbox->irq_send_empty);
- mbox_chan_txdone(&apple_mbox->chan, 0);
- return IRQ_HANDLED;
-}
-
-static int apple_mbox_poll(struct apple_mbox *apple_mbox)
-{
- struct apple_mbox_msg msg;
- int ret = 0;
-
- while (apple_mbox_hw_recv(apple_mbox, &msg) == 0) {
- mbox_chan_received_data(&apple_mbox->chan, (void *)&msg);
- ret++;
- }
-
- /*
- * The interrupt will keep firing even if there are no more messages
- * unless we also acknowledge it at the mailbox level here.
- * There's no race if a message comes in between the check in the while
- * loop above and the ack below: If a new messages arrives inbetween
- * those two the interrupt will just fire again immediately after the
- * ack since it's level triggered.
- */
- if (apple_mbox->hw->has_irq_controls) {
- writel_relaxed(apple_mbox->hw->irq_bit_recv_not_empty,
- apple_mbox->regs + apple_mbox->hw->irq_ack);
- }
-
- return ret;
-}
-
-static irqreturn_t apple_mbox_recv_irq(int irq, void *data)
-{
- struct apple_mbox *apple_mbox = data;
-
- spin_lock(&apple_mbox->rx_lock);
- apple_mbox_poll(apple_mbox);
- spin_unlock(&apple_mbox->rx_lock);
-
- return IRQ_HANDLED;
-}
-
-static bool apple_mbox_chan_peek_data(struct mbox_chan *chan)
-{
- struct apple_mbox *apple_mbox = chan->con_priv;
- unsigned long flags;
- int ret;
-
- spin_lock_irqsave(&apple_mbox->rx_lock, flags);
- ret = apple_mbox_poll(apple_mbox);
- spin_unlock_irqrestore(&apple_mbox->rx_lock, flags);
-
- return ret > 0;
-}
-
-static int apple_mbox_chan_flush(struct mbox_chan *chan, unsigned long timeout)
-{
- struct apple_mbox *apple_mbox = chan->con_priv;
- unsigned long deadline = jiffies + msecs_to_jiffies(timeout);
-
- while (time_before(jiffies, deadline)) {
- if (apple_mbox_hw_send_empty(apple_mbox)) {
- mbox_chan_txdone(&apple_mbox->chan, 0);
- return 0;
- }
-
- udelay(1);
- }
-
- return -ETIME;
-}
-
-static int apple_mbox_chan_startup(struct mbox_chan *chan)
-{
- struct apple_mbox *apple_mbox = chan->con_priv;
-
- /*
- * Only some variants of this mailbox HW provide interrupt control
- * at the mailbox level. We therefore need to handle enabling/disabling
- * interrupts at the main interrupt controller anyway for hardware that
- * doesn't. Just always keep the interrupts we care about enabled at
- * the mailbox level so that both hardware revisions behave almost
- * the same.
- */
- if (apple_mbox->hw->has_irq_controls) {
- writel_relaxed(apple_mbox->hw->irq_bit_recv_not_empty |
- apple_mbox->hw->irq_bit_send_empty,
- apple_mbox->regs + apple_mbox->hw->irq_enable);
- }
-
- enable_irq(apple_mbox->irq_recv_not_empty);
- return 0;
-}
-
-static void apple_mbox_chan_shutdown(struct mbox_chan *chan)
-{
- struct apple_mbox *apple_mbox = chan->con_priv;
-
- disable_irq(apple_mbox->irq_recv_not_empty);
-}
-
-static const struct mbox_chan_ops apple_mbox_ops = {
- .send_data = apple_mbox_chan_send_data,
- .peek_data = apple_mbox_chan_peek_data,
- .flush = apple_mbox_chan_flush,
- .startup = apple_mbox_chan_startup,
- .shutdown = apple_mbox_chan_shutdown,
-};
-
-static struct mbox_chan *apple_mbox_of_xlate(struct mbox_controller *mbox,
- const struct of_phandle_args *args)
-{
- if (args->args_count != 0)
- return ERR_PTR(-EINVAL);
-
- return &mbox->chans[0];
-}
-
-static int apple_mbox_probe(struct platform_device *pdev)
-{
- int ret;
- const struct of_device_id *match;
- char *irqname;
- struct apple_mbox *mbox;
- struct device *dev = &pdev->dev;
-
- match = of_match_node(apple_mbox_of_match, pdev->dev.of_node);
- if (!match)
- return -EINVAL;
- if (!match->data)
- return -EINVAL;
-
- mbox = devm_kzalloc(dev, sizeof(*mbox), GFP_KERNEL);
- if (!mbox)
- return -ENOMEM;
- platform_set_drvdata(pdev, mbox);
-
- mbox->dev = dev;
- mbox->regs = devm_platform_ioremap_resource(pdev, 0);
- if (IS_ERR(mbox->regs))
- return PTR_ERR(mbox->regs);
-
- mbox->hw = match->data;
- mbox->irq_recv_not_empty =
- platform_get_irq_byname(pdev, "recv-not-empty");
- if (mbox->irq_recv_not_empty < 0)
- return -ENODEV;
-
- mbox->irq_send_empty = platform_get_irq_byname(pdev, "send-empty");
- if (mbox->irq_send_empty < 0)
- return -ENODEV;
-
- mbox->controller.dev = mbox->dev;
- mbox->controller.num_chans = 1;
- mbox->controller.chans = &mbox->chan;
- mbox->controller.ops = &apple_mbox_ops;
- mbox->controller.txdone_irq = true;
- mbox->controller.of_xlate = apple_mbox_of_xlate;
- mbox->chan.con_priv = mbox;
- spin_lock_init(&mbox->rx_lock);
-
- irqname = devm_kasprintf(dev, GFP_KERNEL, "%s-recv", dev_name(dev));
- if (!irqname)
- return -ENOMEM;
-
- ret = devm_request_threaded_irq(dev, mbox->irq_recv_not_empty, NULL,
- apple_mbox_recv_irq,
- IRQF_NO_AUTOEN | IRQF_ONESHOT, irqname,
- mbox);
- if (ret)
- return ret;
-
- irqname = devm_kasprintf(dev, GFP_KERNEL, "%s-send", dev_name(dev));
- if (!irqname)
- return -ENOMEM;
-
- ret = devm_request_irq(dev, mbox->irq_send_empty,
- apple_mbox_send_empty_irq, IRQF_NO_AUTOEN,
- irqname, mbox);
- if (ret)
- return ret;
-
- return devm_mbox_controller_register(dev, &mbox->controller);
-}
-
-static const struct apple_mbox_hw apple_mbox_asc_hw = {
- .control_full = APPLE_ASC_MBOX_CONTROL_FULL,
- .control_empty = APPLE_ASC_MBOX_CONTROL_EMPTY,
-
- .a2i_control = APPLE_ASC_MBOX_A2I_CONTROL,
- .a2i_send0 = APPLE_ASC_MBOX_A2I_SEND0,
- .a2i_send1 = APPLE_ASC_MBOX_A2I_SEND1,
-
- .i2a_control = APPLE_ASC_MBOX_I2A_CONTROL,
- .i2a_recv0 = APPLE_ASC_MBOX_I2A_RECV0,
- .i2a_recv1 = APPLE_ASC_MBOX_I2A_RECV1,
-
- .has_irq_controls = false,
-};
-
-static const struct apple_mbox_hw apple_mbox_m3_hw = {
- .control_full = APPLE_M3_MBOX_CONTROL_FULL,
- .control_empty = APPLE_M3_MBOX_CONTROL_EMPTY,
-
- .a2i_control = APPLE_M3_MBOX_A2I_CONTROL,
- .a2i_send0 = APPLE_M3_MBOX_A2I_SEND0,
- .a2i_send1 = APPLE_M3_MBOX_A2I_SEND1,
-
- .i2a_control = APPLE_M3_MBOX_I2A_CONTROL,
- .i2a_recv0 = APPLE_M3_MBOX_I2A_RECV0,
- .i2a_recv1 = APPLE_M3_MBOX_I2A_RECV1,
-
- .has_irq_controls = true,
- .irq_enable = APPLE_M3_MBOX_IRQ_ENABLE,
- .irq_ack = APPLE_M3_MBOX_IRQ_ACK,
- .irq_bit_recv_not_empty = APPLE_M3_MBOX_IRQ_I2A_NOT_EMPTY,
- .irq_bit_send_empty = APPLE_M3_MBOX_IRQ_A2I_EMPTY,
-};
-
-static const struct of_device_id apple_mbox_of_match[] = {
- { .compatible = "apple,asc-mailbox-v4", .data = &apple_mbox_asc_hw },
- { .compatible = "apple,m3-mailbox-v2", .data = &apple_mbox_m3_hw },
- {}
-};
-MODULE_DEVICE_TABLE(of, apple_mbox_of_match);
-
-static struct platform_driver apple_mbox_driver = {
- .driver = {
- .name = "apple-mailbox",
- .of_match_table = apple_mbox_of_match,
- },
- .probe = apple_mbox_probe,
-};
-module_platform_driver(apple_mbox_driver);
-
-MODULE_LICENSE("Dual MIT/GPL");
-MODULE_AUTHOR("Sven Peter <sven@svenpeter.dev>");
-MODULE_DESCRIPTION("Apple Mailbox driver");
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