--- /dev/null
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * i2c support for Silicon Labs' CP2615 Digital Audio Bridge
+ *
+ * (c) 2021, Bence Csókás <bence98@sch.bme.hu>
+ */
+
+#include <linux/errno.h>
+#include <linux/i2c.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/string.h>
+#include <linux/usb.h>
+
+/** CP2615 I/O Protocol implementation */
+
+#define CP2615_VID 0x10c4
+#define CP2615_PID 0xeac1
+
+#define IOP_EP_IN 0x82
+#define IOP_EP_OUT 0x02
+#define IOP_IFN 1
+#define IOP_ALTSETTING 2
+
+#define MAX_IOP_SIZE 64
+#define MAX_IOP_PAYLOAD_SIZE (MAX_IOP_SIZE - 6)
+#define MAX_I2C_SIZE (MAX_IOP_PAYLOAD_SIZE - 4)
+
+enum cp2615_iop_msg_type {
+ iop_GetAccessoryInfo = 0xD100,
+ iop_AccessoryInfo = 0xA100,
+ iop_GetPortConfiguration = 0xD203,
+ iop_PortConfiguration = 0xA203,
+ iop_DoI2cTransfer = 0xD400,
+ iop_I2cTransferResult = 0xA400,
+ iop_GetSerialState = 0xD501,
+ iop_SerialState = 0xA501
+};
+
+struct __packed cp2615_iop_msg {
+ __be16 preamble, length, msg;
+ u8 data[MAX_IOP_PAYLOAD_SIZE];
+};
+
+#define PART_ID_A01 0x1400
+#define PART_ID_A02 0x1500
+
+struct __packed cp2615_iop_accessory_info {
+ __be16 part_id, option_id, proto_ver;
+};
+
+struct __packed cp2615_i2c_transfer {
+ u8 tag, i2caddr, read_len, write_len;
+ u8 data[MAX_I2C_SIZE];
+};
+
+/* Possible values for struct cp2615_i2c_transfer_result.status */
+enum cp2615_i2c_status {
+ /* Writing to the internal EEPROM failed, because it is locked */
+ CP2615_CFG_LOCKED = -6,
+ /* read_len or write_len out of range */
+ CP2615_INVALID_PARAM = -4,
+ /* I2C slave did not ACK in time */
+ CP2615_TIMEOUT,
+ /* I2C bus busy */
+ CP2615_BUS_BUSY,
+ /* I2C bus error (ie. device NAK'd the request) */
+ CP2615_BUS_ERROR,
+ CP2615_SUCCESS
+};
+
+struct __packed cp2615_i2c_transfer_result {
+ u8 tag, i2caddr;
+ s8 status;
+ u8 read_len;
+ u8 data[MAX_I2C_SIZE];
+};
+
+static int cp2615_init_iop_msg(struct cp2615_iop_msg *ret, enum cp2615_iop_msg_type msg,
+ const void *data, size_t data_len)
+{
+ if (data_len > MAX_IOP_PAYLOAD_SIZE)
+ return -EFBIG;
+
+ if (!ret)
+ return -EINVAL;
+
+ ret->preamble = 0x2A2A;
+ ret->length = htons(data_len + 6);
+ ret->msg = htons(msg);
+ if (data && data_len)
+ memcpy(&ret->data, data, data_len);
+ return 0;
+}
+
+static int cp2615_init_i2c_msg(struct cp2615_iop_msg *ret, const struct cp2615_i2c_transfer *data)
+{
+ return cp2615_init_iop_msg(ret, iop_DoI2cTransfer, data, 4 + data->write_len);
+}
+
+/* Translates status codes to Linux errno's */
+static int cp2615_check_status(enum cp2615_i2c_status status)
+{
+ switch (status) {
+ case CP2615_SUCCESS:
+ return 0;
+ case CP2615_BUS_ERROR:
+ return -ENXIO;
+ case CP2615_BUS_BUSY:
+ return -EAGAIN;
+ case CP2615_TIMEOUT:
+ return -ETIMEDOUT;
+ case CP2615_INVALID_PARAM:
+ return -EINVAL;
+ case CP2615_CFG_LOCKED:
+ return -EPERM;
+ }
+ /* Unknown error code */
+ return -EPROTO;
+}
+
+/** Driver code */
+
+static int
+cp2615_i2c_send(struct usb_interface *usbif, struct cp2615_i2c_transfer *i2c_w)
+{
+ struct cp2615_iop_msg *msg = kzalloc(sizeof(*msg), GFP_KERNEL);
+ struct usb_device *usbdev = interface_to_usbdev(usbif);
+ int res = cp2615_init_i2c_msg(msg, i2c_w);
+
+ if (!res)
+ res = usb_bulk_msg(usbdev, usb_sndbulkpipe(usbdev, IOP_EP_OUT),
+ msg, ntohs(msg->length), NULL, 0);
+ kfree(msg);
+ return res;
+}
+
+static int
+cp2615_i2c_recv(struct usb_interface *usbif, unsigned char tag, void *buf)
+{
+ struct cp2615_iop_msg *msg = kzalloc(sizeof(*msg), GFP_KERNEL);
+ struct cp2615_i2c_transfer_result *i2c_r = (struct cp2615_i2c_transfer_result *)&msg->data;
+ struct usb_device *usbdev = interface_to_usbdev(usbif);
+ int res = usb_bulk_msg(usbdev, usb_rcvbulkpipe(usbdev, IOP_EP_IN),
+ msg, sizeof(struct cp2615_iop_msg), NULL, 0);
+
+ if (res < 0) {
+ kfree(msg);
+ return res;
+ }
+
+ if (msg->msg != htons(iop_I2cTransferResult) || i2c_r->tag != tag) {
+ kfree(msg);
+ return -EIO;
+ }
+
+ res = cp2615_check_status(i2c_r->status);
+ if (!res)
+ memcpy(buf, &i2c_r->data, i2c_r->read_len);
+
+ kfree(msg);
+ return res;
+}
+
+/* Checks if the IOP is functional by querying the part's ID */
+static int cp2615_check_iop(struct usb_interface *usbif)
+{
+ struct cp2615_iop_msg *msg = kzalloc(sizeof(*msg), GFP_KERNEL);
+ struct cp2615_iop_accessory_info *info = (struct cp2615_iop_accessory_info *)&msg->data;
+ struct usb_device *usbdev = interface_to_usbdev(usbif);
+ int res = cp2615_init_iop_msg(msg, iop_GetAccessoryInfo, NULL, 0);
+
+ if (res)
+ goto out;
+
+ res = usb_bulk_msg(usbdev, usb_sndbulkpipe(usbdev, IOP_EP_OUT),
+ msg, ntohs(msg->length), NULL, 0);
+ if (res)
+ goto out;
+
+ res = usb_bulk_msg(usbdev, usb_rcvbulkpipe(usbdev, IOP_EP_IN),
+ msg, sizeof(struct cp2615_iop_msg), NULL, 0);
+ if (res)
+ goto out;
+
+ if (msg->msg != htons(iop_AccessoryInfo)) {
+ res = -EIO;
+ goto out;
+ }
+
+ switch (ntohs(info->part_id)) {
+ case PART_ID_A01:
+ dev_dbg(&usbif->dev, "Found A01 part. (WARNING: errata exists!)\n");
+ break;
+ case PART_ID_A02:
+ dev_dbg(&usbif->dev, "Found good A02 part.\n");
+ break;
+ default:
+ dev_warn(&usbif->dev, "Unknown part ID %04X\n", ntohs(info->part_id));
+ }
+
+out:
+ kfree(msg);
+ return res;
+}
+
+static int
+cp2615_i2c_master_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs, int num)
+{
+ struct usb_interface *usbif = adap->algo_data;
+ int i = 0, ret = 0;
+ struct i2c_msg *msg;
+ struct cp2615_i2c_transfer i2c_w = {0};
+
+ dev_dbg(&usbif->dev, "Doing %d I2C transactions\n", num);
+
+ for (; !ret && i < num; i++) {
+ msg = &msgs[i];
+
+ i2c_w.tag = 0xdd;
+ i2c_w.i2caddr = i2c_8bit_addr_from_msg(msg);
+ if (msg->flags & I2C_M_RD) {
+ i2c_w.read_len = msg->len;
+ i2c_w.write_len = 0;
+ } else {
+ i2c_w.read_len = 0;
+ i2c_w.write_len = msg->len;
+ memcpy(&i2c_w.data, msg->buf, i2c_w.write_len);
+ }
+ ret = cp2615_i2c_send(usbif, &i2c_w);
+ if (ret)
+ break;
+ ret = cp2615_i2c_recv(usbif, i2c_w.tag, msg->buf);
+ }
+ if (ret < 0)
+ return ret;
+ return i;
+}
+
+static u32
+cp2615_i2c_func(struct i2c_adapter *adap)
+{
+ return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL;
+}
+
+static const struct i2c_algorithm cp2615_i2c_algo = {
+ .master_xfer = cp2615_i2c_master_xfer,
+ .functionality = cp2615_i2c_func,
+};
+
+/*
+ * This chip has some limitations: one is that the USB endpoint
+ * can only receive 64 bytes/transfer, that leaves 54 bytes for
+ * the I2C transfer. On top of that, EITHER read_len OR write_len
+ * may be zero, but not both. If both are non-zero, the adapter
+ * issues a write followed by a read. And the chip does not
+ * support repeated START between the write and read phases.
+ */
+static struct i2c_adapter_quirks cp2615_i2c_quirks = {
+ .max_write_len = MAX_I2C_SIZE,
+ .max_read_len = MAX_I2C_SIZE,
+ .flags = I2C_AQ_COMB_WRITE_THEN_READ | I2C_AQ_NO_ZERO_LEN | I2C_AQ_NO_REP_START,
+ .max_comb_1st_msg_len = MAX_I2C_SIZE,
+ .max_comb_2nd_msg_len = MAX_I2C_SIZE
+};
+
+static void
+cp2615_i2c_remove(struct usb_interface *usbif)
+{
+ struct i2c_adapter *adap = usb_get_intfdata(usbif);
+
+ usb_set_intfdata(usbif, NULL);
+ i2c_del_adapter(adap);
+}
+
+static int
+cp2615_i2c_probe(struct usb_interface *usbif, const struct usb_device_id *id)
+{
+ int ret = 0;
+ struct i2c_adapter *adap;
+ struct usb_device *usbdev = interface_to_usbdev(usbif);
+
+ ret = usb_set_interface(usbdev, IOP_IFN, IOP_ALTSETTING);
+ if (ret)
+ return ret;
+
+ ret = cp2615_check_iop(usbif);
+ if (ret)
+ return ret;
+
+ adap = devm_kzalloc(&usbif->dev, sizeof(struct i2c_adapter), GFP_KERNEL);
+ if (!adap)
+ return -ENOMEM;
+
+ strncpy(adap->name, usbdev->serial, sizeof(adap->name) - 1);
+ adap->owner = THIS_MODULE;
+ adap->dev.parent = &usbif->dev;
+ adap->dev.of_node = usbif->dev.of_node;
+ adap->timeout = HZ;
+ adap->algo = &cp2615_i2c_algo;
+ adap->quirks = &cp2615_i2c_quirks;
+ adap->algo_data = usbif;
+
+ ret = i2c_add_adapter(adap);
+ if (ret)
+ return ret;
+
+ usb_set_intfdata(usbif, adap);
+ return 0;
+}
+
+static const struct usb_device_id id_table[] = {
+ { USB_DEVICE_INTERFACE_NUMBER(CP2615_VID, CP2615_PID, IOP_IFN) },
+ { }
+};
+
+MODULE_DEVICE_TABLE(usb, id_table);
+
+static struct usb_driver cp2615_i2c_driver = {
+ .name = "i2c-cp2615",
+ .probe = cp2615_i2c_probe,
+ .disconnect = cp2615_i2c_remove,
+ .id_table = id_table,
+};
+
+module_usb_driver(cp2615_i2c_driver);
+
+MODULE_AUTHOR("Bence Csókás <bence98@sch.bme.hu>");
+MODULE_DESCRIPTION("CP2615 I2C bus driver");
+MODULE_LICENSE("GPL");
projects / linux.git / commitdiff