Quelle  i2c-digicolor.c   Sprache: C

// SPDX-License-Identifier: GPL-2.0-only
/*
 * I2C bus driver for Conexant Digicolor SoCs
 *
 * Author: Baruch Siach <baruch@tkos.co.il>
 *
 * Copyright (C) 2015 Paradox Innovation Ltd.
 */

#include <linux/clk.h>
#include <linux/completion.h>
#include <linux/delay.h>
#include <linux/i2c.h>
#include <linux/interrupt.h>
#include <linux/io.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/of.h>
#include <linux/platform_device.h>

#define TIMEOUT_MS  100

#define II_CONTROL  0x0
#define II_CONTROL_LOCAL_RESET BIT(0)

#define II_CLOCKTIME  0x1

#define II_COMMAND  0x2
#define II_CMD_START  1
#define II_CMD_RESTART  2
#define II_CMD_SEND_ACK  3
#define II_CMD_GET_ACK  6
#define II_CMD_GET_NOACK 7
#define II_CMD_STOP  10
#define II_COMMAND_GO  BIT(7)
#define II_COMMAND_COMPLETION_STATUS(r) (((r) >> 5) & 3)
#define II_CMD_STATUS_NORMAL 0
#define II_CMD_STATUS_ACK_GOOD 1
#define II_CMD_STATUS_ACK_BAD 2
#define II_CMD_STATUS_ABORT 3

#define II_DATA   0x3
#define II_INTFLAG_CLEAR 0x8
#define II_INTENABLE  0xa

struct dc_i2c {
 struct i2c_adapter adap;
 struct device  *dev;
 void __iomem  *regs;
 struct clk  *clk;
 unsigned int  frequency;

 struct i2c_msg  *msg;
 unsigned int  msgbuf_ptr;
 int   last;
 spinlock_t  lock;
 struct completion done;
 int   state;
 int   error;
};

enum {
 STATE_IDLE,
 STATE_START,
 STATE_ADDR,
 STATE_WRITE,
 STATE_READ,
 STATE_STOP,
};

static void dc_i2c_cmd(struct dc_i2c *i2c, u8 cmd)
{
 writeb_relaxed(cmd | II_COMMAND_GO, i2c->regs + II_COMMAND);
}

static u8 dc_i2c_addr_cmd(struct i2c_msg *msg)
{
 u8 addr = (msg->addr & 0x7f) << 1;

 if (msg->flags & I2C_M_RD)
  addr |= 1;

 return addr;
}

static void dc_i2c_data(struct dc_i2c *i2c, u8 data)
{
 writeb_relaxed(data, i2c->regs + II_DATA);
}

static void dc_i2c_write_byte(struct dc_i2c *i2c, u8 byte)
{
 dc_i2c_data(i2c, byte);
 dc_i2c_cmd(i2c, II_CMD_SEND_ACK);
}

static void dc_i2c_write_buf(struct dc_i2c *i2c)
{
 dc_i2c_write_byte(i2c, i2c->msg->buf[i2c->msgbuf_ptr++]);
}

static void dc_i2c_next_read(struct dc_i2c *i2c)
{
 bool last = (i2c->msgbuf_ptr + 1 == i2c->msg->len);

 dc_i2c_cmd(i2c, last ? II_CMD_GET_NOACK : II_CMD_GET_ACK);
}

static void dc_i2c_stop(struct dc_i2c *i2c)
{
 i2c->state = STATE_STOP;
 if (i2c->last)
  dc_i2c_cmd(i2c, II_CMD_STOP);
 else
  complete(&i2c->done);
}

static u8 dc_i2c_read_byte(struct dc_i2c *i2c)
{
 return readb_relaxed(i2c->regs + II_DATA);
}

static void dc_i2c_read_buf(struct dc_i2c *i2c)
{
 i2c->msg->buf[i2c->msgbuf_ptr++] = dc_i2c_read_byte(i2c);
 dc_i2c_next_read(i2c);
}

static void dc_i2c_set_irq(struct dc_i2c *i2c, int enable)
{
 if (enable)
  writeb_relaxed(1, i2c->regs + II_INTFLAG_CLEAR);
 writeb_relaxed(!!enable, i2c->regs + II_INTENABLE);
}

static int dc_i2c_cmd_status(struct dc_i2c *i2c)
{
 u8 cmd = readb_relaxed(i2c->regs + II_COMMAND);

 return II_COMMAND_COMPLETION_STATUS(cmd);
}

static void dc_i2c_start_msg(struct dc_i2c *i2c, int first)
{
 struct i2c_msg *msg = i2c->msg;

 if (!(msg->flags & I2C_M_NOSTART)) {
  i2c->state = STATE_START;
  dc_i2c_cmd(i2c, first ? II_CMD_START : II_CMD_RESTART);
 } else if (msg->flags & I2C_M_RD) {
  i2c->state = STATE_READ;
  dc_i2c_next_read(i2c);
 } else {
  i2c->state = STATE_WRITE;
  dc_i2c_write_buf(i2c);
 }
}

static irqreturn_t dc_i2c_irq(int irq, void *dev_id)
{
 struct dc_i2c *i2c = dev_id;
 int cmd_status = dc_i2c_cmd_status(i2c);
 u8 addr_cmd;

 writeb_relaxed(1, i2c->regs + II_INTFLAG_CLEAR);

 spin_lock(&i2c->lock);

 if (cmd_status == II_CMD_STATUS_ACK_BAD
     || cmd_status == II_CMD_STATUS_ABORT) {
  i2c->error = -EIO;
  complete(&i2c->done);
  goto out;
 }

 switch (i2c->state) {
 case STATE_START:
  addr_cmd = dc_i2c_addr_cmd(i2c->msg);
  dc_i2c_write_byte(i2c, addr_cmd);
  i2c->state = STATE_ADDR;
  break;
 case STATE_ADDR:
  if (i2c->msg->flags & I2C_M_RD) {
   dc_i2c_next_read(i2c);
   i2c->state = STATE_READ;
   break;
  }
  i2c->state = STATE_WRITE;
  fallthrough;
 case STATE_WRITE:
  if (i2c->msgbuf_ptr < i2c->msg->len)
   dc_i2c_write_buf(i2c);
  else
   dc_i2c_stop(i2c);
  break;
 case STATE_READ:
  if (i2c->msgbuf_ptr < i2c->msg->len)
   dc_i2c_read_buf(i2c);
  else
   dc_i2c_stop(i2c);
  break;
 case STATE_STOP:
  i2c->state = STATE_IDLE;
  complete(&i2c->done);
  break;
 }

out:
 spin_unlock(&i2c->lock);
 return IRQ_HANDLED;
}

static int dc_i2c_xfer_msg(struct dc_i2c *i2c, struct i2c_msg *msg, int first,
      int last)
{
 unsigned long time_left = msecs_to_jiffies(TIMEOUT_MS);
 unsigned long flags;

 spin_lock_irqsave(&i2c->lock, flags);
 i2c->msg = msg;
 i2c->msgbuf_ptr = 0;
 i2c->last = last;
 i2c->error = 0;

 reinit_completion(&i2c->done);
 dc_i2c_set_irq(i2c, 1);
 dc_i2c_start_msg(i2c, first);
 spin_unlock_irqrestore(&i2c->lock, flags);

 time_left = wait_for_completion_timeout(&i2c->done, time_left);
 dc_i2c_set_irq(i2c, 0);
 if (time_left == 0) {
  i2c->state = STATE_IDLE;
  return -ETIMEDOUT;
 }

 if (i2c->error)
  return i2c->error;

 return 0;
}

static int dc_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs, int num)
{
 struct dc_i2c *i2c = adap->algo_data;
 int i, ret;

 for (i = 0; i < num; i++) {
  ret = dc_i2c_xfer_msg(i2c, &msgs[i], i == 0, i == num - 1);
  if (ret)
   return ret;
 }

 return num;
}

static int dc_i2c_init_hw(struct dc_i2c *i2c)
{
 unsigned long clk_rate = clk_get_rate(i2c->clk);
 unsigned int clocktime;

 writeb_relaxed(II_CONTROL_LOCAL_RESET, i2c->regs + II_CONTROL);
 udelay(100);
 writeb_relaxed(0, i2c->regs + II_CONTROL);
 udelay(100);

 clocktime = DIV_ROUND_UP(clk_rate, 64 * i2c->frequency);
 if (clocktime < 1 || clocktime > 0xff) {
  dev_err(i2c->dev, "can't set bus speed of %u Hz\n",
   i2c->frequency);
  return -EINVAL;
 }
 writeb_relaxed(clocktime - 1, i2c->regs + II_CLOCKTIME);

 return 0;
}

static u32 dc_i2c_func(struct i2c_adapter *adap)
{
 return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL | I2C_FUNC_NOSTART;
}

static const struct i2c_algorithm dc_i2c_algorithm = {
 .xfer = dc_i2c_xfer,
 .functionality = dc_i2c_func,
};

static int dc_i2c_probe(struct platform_device *pdev)
{
 struct device_node *np = pdev->dev.of_node;
 struct dc_i2c *i2c;
 int ret = 0, irq;

 i2c = devm_kzalloc(&pdev->dev, sizeof(struct dc_i2c), GFP_KERNEL);
 if (!i2c)
  return -ENOMEM;

 if (of_property_read_u32(pdev->dev.of_node, "clock-frequency",
     &i2c->frequency))
  i2c->frequency = I2C_MAX_STANDARD_MODE_FREQ;

 i2c->dev = &pdev->dev;
 platform_set_drvdata(pdev, i2c);

 spin_lock_init(&i2c->lock);
 init_completion(&i2c->done);

 i2c->clk = devm_clk_get(&pdev->dev, NULL);
 if (IS_ERR(i2c->clk))
  return PTR_ERR(i2c->clk);

 i2c->regs = devm_platform_ioremap_resource(pdev, 0);
 if (IS_ERR(i2c->regs))
  return PTR_ERR(i2c->regs);

 irq = platform_get_irq(pdev, 0);
 if (irq < 0)
  return irq;

 ret = devm_request_irq(&pdev->dev, irq, dc_i2c_irq, 0,
          dev_name(&pdev->dev), i2c);
 if (ret < 0)
  return ret;

 strscpy(i2c->adap.name, "Conexant Digicolor I2C adapter",
  sizeof(i2c->adap.name));
 i2c->adap.owner = THIS_MODULE;
 i2c->adap.algo = &dc_i2c_algorithm;
 i2c->adap.dev.parent = &pdev->dev;
 i2c->adap.dev.of_node = np;
 i2c->adap.algo_data = i2c;

 ret = dc_i2c_init_hw(i2c);
 if (ret)
  return ret;

 ret = clk_prepare_enable(i2c->clk);
 if (ret < 0)
  return ret;

 ret = i2c_add_adapter(&i2c->adap);
 if (ret < 0) {
  clk_disable_unprepare(i2c->clk);
  return ret;
 }

 return 0;
}

static void dc_i2c_remove(struct platform_device *pdev)
{
 struct dc_i2c *i2c = platform_get_drvdata(pdev);

 i2c_del_adapter(&i2c->adap);
 clk_disable_unprepare(i2c->clk);
}

static const struct of_device_id dc_i2c_match[] = {
 { .compatible = "cnxt,cx92755-i2c" },
 { }
};
MODULE_DEVICE_TABLE(of, dc_i2c_match);

static struct platform_driver dc_i2c_driver = {
 .probe   = dc_i2c_probe,
 .remove = dc_i2c_remove,
 .driver  = {
  .name  = "digicolor-i2c",
  .of_match_table = dc_i2c_match,
 },
};
module_platform_driver(dc_i2c_driver);

MODULE_AUTHOR("Baruch Siach ");
MODULE_DESCRIPTION("Conexant Digicolor I2C controller driver");
MODULE_LICENSE("GPL v2");