#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 <baruch@tkos.co.il>");
MODULE_DESCRIPTION("Conexant Digicolor I2C controller driver");
MODULE_LICENSE("GPL v2");
