This driver implements tunnelling of i2c requests over GMSL via a
MAX9260 deserializer. It provides an i2c adapter that can be used
to reach devices on the far side of the link.
Signed-off-by: Ulrich Hecht <ulrich.hecht+renesas@xxxxxxxxx>
---
drivers/media/i2c/Kconfig | 6 +
drivers/media/i2c/Makefile | 1 +
drivers/media/i2c/max9260.c | 294 ++++++++++++++++++++++++++++++++++++++++++++
3 files changed, 301 insertions(+)
create mode 100644 drivers/media/i2c/max9260.c
diff --git a/drivers/media/i2c/Kconfig b/drivers/media/i2c/Kconfig
index 7c23b7a..743f8ee 100644
--- a/drivers/media/i2c/Kconfig
+++ b/drivers/media/i2c/Kconfig
@@ -400,6 +400,12 @@ config VIDEO_VPX3220
To compile this driver as a module, choose M here: the
module will be called vpx3220.
+config VIDEO_MAX9260
+ tristate "Maxim MAX9260 GMSL deserializer support"
+ depends on I2C
+ ---help---
+ This driver supports the Maxim MAX9260 GMSL deserializer.
+
comment "Video and audio decoders"
config VIDEO_SAA717X
diff --git a/drivers/media/i2c/Makefile b/drivers/media/i2c/Makefile
index 62323ec..9b2fd13 100644
--- a/drivers/media/i2c/Makefile
+++ b/drivers/media/i2c/Makefile
@@ -86,3 +86,4 @@ obj-$(CONFIG_VIDEO_IR_I2C) += ir-kbd-i2c.o
obj-$(CONFIG_VIDEO_ML86V7667) += ml86v7667.o
obj-$(CONFIG_VIDEO_OV2659) += ov2659.o
obj-$(CONFIG_VIDEO_TC358743) += tc358743.o
+obj-$(CONFIG_VIDEO_MAX9260) += max9260.o
diff --git a/drivers/media/i2c/max9260.c b/drivers/media/i2c/max9260.c
new file mode 100644
index 0000000..2030eb0
--- /dev/null
+++ b/drivers/media/i2c/max9260.c
@@ -0,0 +1,294 @@
+/*
+ * Maxim MAX9260 GMSL Deserializer Driver
+ *
+ * Copyright (C) 2017 Ulrich Hecht
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by the
+ * Free Software Foundation; either version 2 of the License, or (at your
+ * option) any later version.
+ */
+
+#include <linux/device.h>
+#include <linux/i2c.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/of_gpio.h>
+#include <linux/serdev.h>
+#include <linux/slab.h>
+#include <linux/tty.h>
+
+#define SYNC 0x79
+#define ACK 0xc3
+
+#define RX_FINISHED 0
+#define RX_FRAME_ERROR 1
+#define RX_EXPECT_ACK 2
+#define RX_EXPECT_ACK_DATA 3
+#define RX_EXPECT_DATA 4
+
+struct max9260_device {
+ struct serdev_device *serdev;
+ u8 *rx_buf;
+ int rx_len;
+ int rx_state;
+ wait_queue_head_t rx_wq;
+ struct i2c_adapter adap;
+};
+
+static void wait_for_transaction(struct max9260_device *dev)
+{
+ wait_event_interruptible_timeout(dev->rx_wq,
+ dev->rx_state <= RX_FRAME_ERROR,
+ HZ/2);
+}
+
+static void transact(struct max9260_device *dev,
+ int expect,
+ u8 *request, int len)
+{
+ serdev_device_mux_select(dev->serdev);
+
+ serdev_device_set_baudrate(dev->serdev, 115200);
+ serdev_device_set_parity(dev->serdev, 1, 0);
+
+ dev->rx_state = expect;
+ serdev_device_write_buf(dev->serdev, request, len);
+
+ wait_for_transaction(dev);
+
+ serdev_device_mux_deselect(dev->serdev);
+}
+
+static int max9260_read_reg(struct max9260_device *dev, int reg)
+{
+ u8 request[] = { 0x79, 0x91, reg, 1 };
+ u8 rx;
+
+ dev->rx_len = 1;
+ dev->rx_buf = ℞
+
+ transact(dev, RX_EXPECT_ACK_DATA, request, 4);
+
+ if (dev->rx_state == RX_FINISHED)
+ return rx;
+
+ return -1;
+}
+
+static int max9260_setup(struct max9260_device *dev)
+{
+ int ret;
+
+ ret = max9260_read_reg(dev, 0x1e);
+
+ if (ret != 0x02) {
+ dev_err(&dev->serdev->dev,
+ "device does not identify as MAX9260\n");
+ return -EINVAL;
+ }
+
+ return 0;
+}
+
+static void max9260_uart_write_wakeup(struct serdev_device *serdev)
+{
+}
+
+static int max9260_uart_receive_buf(struct serdev_device *serdev,
+ const u8 *data, size_t count)
+{
+ struct max9260_device *dev = serdev_device_get_drvdata(serdev);
+ int accepted;
+
+ switch (dev->rx_state) {
+ case RX_FINISHED:
+ dev_dbg(&dev->serdev->dev, "excess data ignored\n");
+ return count;
+
+ case RX_EXPECT_ACK:
+ case RX_EXPECT_ACK_DATA:
+ if (data[0] != ACK) {
+ dev_dbg(&dev->serdev->dev, "frame error");
+ dev->rx_state = RX_FRAME_ERROR;
+ wake_up_interruptible(&dev->rx_wq);
+ return 1;
+ }
+ switch (dev->rx_state) {
+ case RX_EXPECT_ACK_DATA:
+ dev->rx_state = RX_EXPECT_DATA;
+ break;
+ case RX_EXPECT_ACK:
+ dev->rx_state = RX_FINISHED;
+ wake_up_interruptible(&dev->rx_wq);
+ break;
+ }
+ return 1;
+
+ case RX_EXPECT_DATA:
+ accepted = dev->rx_len < count ? dev->rx_len : count;
+
+ memcpy(dev->rx_buf, data, accepted);
+
+ dev->rx_len -= accepted;
+ dev->rx_buf += accepted;
+
+ if (!dev->rx_len) {
+ dev->rx_state = RX_FINISHED;
+ wake_up_interruptible(&dev->rx_wq);
+ }
+
+ return accepted;
+
+ case RX_FRAME_ERROR:
+ dev_dbg(&dev->serdev->dev, "%d bytes ignored\n", count);
+ return count;
+
+ }
+ return 0;
+}
+
+struct serdev_device_ops max9260_serdev_client_ops = {
+ .receive_buf = max9260_uart_receive_buf,
+ .write_wakeup = max9260_uart_write_wakeup,
+};
+
+static u32 max9260_i2c_func(struct i2c_adapter *adapter)
+{
+ return I2C_FUNC_SMBUS_EMUL;
+}
+
+static s32 max9260_smbus_xfer(struct i2c_adapter *adap, u16 addr,
+ unsigned short flags, char read_write, u8 command, int size,
+ union i2c_smbus_data *data)
+{
+ u8 request[] = { SYNC,
+ (addr << 1) + (read_write == I2C_SMBUS_READ),
+ command, 0, 0 };
+ struct max9260_device *dev = i2c_get_adapdata(adap);
+
+ switch (size) {
+ case I2C_SMBUS_BYTE:
+ if (read_write == I2C_SMBUS_WRITE) {
+ transact(dev, RX_EXPECT_ACK, request, 4);
+ dev_dbg(&adap->dev,
+ "smbus byte - addr 0x%02x, wrote 0x%02x.\n",
+ addr, command);
+ } else {
+ /* TBD */
+ return -EOPNOTSUPP;
+ }
+ break;
+
+ case I2C_SMBUS_BYTE_DATA:
+ request[3] = 1;
+ if (read_write == I2C_SMBUS_WRITE) {
+ request[4] = data->byte;
+ transact(dev, RX_EXPECT_ACK, request, 5);
+ dev_dbg(&adap->dev,
+ "smbus byte data - addr 0x%02x, wrote 0x%02x at 0x%02x.\n",
+ addr, data->byte, command);
+ } else {
+ dev->rx_len = 1;
+ dev->rx_buf = &data->byte;
+ transact(dev, RX_EXPECT_ACK_DATA, request, 4);
+ dev_dbg(&adap->dev,
+ "smbus byte data - addr 0x%02x, read 0x%02x at 0x%02x.\n",
+ addr, data->byte, command);
+ }
+ break;
+ default:
+ dev_dbg(&adap->dev,
+ "Unsupported I2C/SMBus command %d\n", size);
+ return -EOPNOTSUPP;
+ }
+
+ if (dev->rx_state != RX_FINISHED) {
+ dev_dbg(&adap->dev, "xfer timed out\n");
+ return -EIO;
+ }
+
+ return 0;
+}
+
+static const struct i2c_algorithm max9260_i2c_algorithm = {
+ .functionality = max9260_i2c_func,
+ .smbus_xfer = max9260_smbus_xfer,
+};
+
+static int max9260_probe(struct serdev_device *serdev)
+{
+ struct max9260_device *dev;
+ struct i2c_adapter *adap;
+ int ret;
+
+ dev = kzalloc(sizeof(*dev), GFP_KERNEL);
+ if (!dev)
+ return -ENOMEM;
+
+ init_waitqueue_head(&dev->rx_wq);
+
+ dev->serdev = serdev;
+ serdev_device_open(serdev);
+ serdev_device_set_drvdata(serdev, dev);
+
+ serdev_device_set_client_ops(serdev, &max9260_serdev_client_ops);
+
+ ret = max9260_setup(dev);
+
+ if (ret < 0)
+ goto err_free;
+
+ adap = &dev->adap;
+ i2c_set_adapdata(adap, dev);
+
+ adap->owner = THIS_MODULE;
+ adap->algo = &max9260_i2c_algorithm;
+ adap->dev.parent = &serdev->dev;
+ adap->retries = 5;
+ adap->nr = -1;
+ strlcpy(adap->name, dev_name(&serdev->dev), sizeof(adap->name));
+
+ ret = i2c_add_numbered_adapter(adap);
+ if (ret < 0) {
+ dev_err(&serdev->dev, "failed to register i2c adapter\n");
+ return ret;
+ }
+
+ return 0;
+
+err_free:
+ kfree(dev);
+ return ret;
+}
+
+static void max9260_remove(struct serdev_device *serdev)
+{
+ struct max9260_device *dev = serdev_device_get_drvdata(serdev);
+
+ serdev_device_close(dev->serdev);
+
+ kfree(dev);
+}
+
+static const struct of_device_id max9260_dt_ids[] = {
+ { .compatible = "maxim,max9260" },
+ {},
+};
+
+MODULE_DEVICE_TABLE(of, max9260_dt_ids);
+
+static struct serdev_device_driver max9260_driver = {
+ .probe = max9260_probe,
+ .remove = max9260_remove,
+ .driver = {
+ .name = "max9260",
+ .of_match_table = of_match_ptr(max9260_dt_ids),
+ },
+};
+
+module_serdev_device_driver(max9260_driver);
+
+MODULE_DESCRIPTION("Maxim MAX9260 GMSL Deserializer Driver");
+MODULE_AUTHOR("Ulrich Hecht");
+MODULE_LICENSE("GPL");
--
2.7.4
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