linux/drivers/i2c/busses/i2c-sirf.c
Guoying Zhang d64d45cb95 i2c: sirf: tune the divider to make i2c bus freq more accurate
In prima2 and atlas7, due to some hardware design issue. we
need to adjust the divider ratio a little according to i2c
bus frequency ranges.
Since i2c is open drain interface that allows the slave to
stall the transaction by holding the SCL line at '0', the RTL
implementation is waiting for SCL feedback from the pin after
setting it to High-Z ('1'). This wait adds to the high-time
interval counter few cycles of the input synchronization
(depending on the SCL_FILTER_REG field), and also the time it
takes for the board pull-up resistor to rise the SCL line.
For slow SCL settings these additions are negligible, but they
start to affect the speed when clock is set to faster frequencies.
This patch is based on the actual tests, and it makes SCL more
accurate.

Signed-off-by: Guoying Zhang <Guoying.Zhang@csr.com>
Signed-off-by: Barry Song <Baohua.Song@csr.com>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
2015-10-23 22:48:45 +02:00

486 lines
13 KiB
C

/*
* I2C bus driver for CSR SiRFprimaII
*
* Copyright (c) 2011 Cambridge Silicon Radio Limited, a CSR plc group company.
*
* Licensed under GPLv2 or later.
*/
#include <linux/interrupt.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/slab.h>
#include <linux/platform_device.h>
#include <linux/i2c.h>
#include <linux/clk.h>
#include <linux/err.h>
#include <linux/io.h>
#define SIRFSOC_I2C_CLK_CTRL 0x00
#define SIRFSOC_I2C_STATUS 0x0C
#define SIRFSOC_I2C_CTRL 0x10
#define SIRFSOC_I2C_IO_CTRL 0x14
#define SIRFSOC_I2C_SDA_DELAY 0x18
#define SIRFSOC_I2C_CMD_START 0x1C
#define SIRFSOC_I2C_CMD_BUF 0x30
#define SIRFSOC_I2C_DATA_BUF 0x80
#define SIRFSOC_I2C_CMD_BUF_MAX 16
#define SIRFSOC_I2C_DATA_BUF_MAX 16
#define SIRFSOC_I2C_CMD(x) (SIRFSOC_I2C_CMD_BUF + (x)*0x04)
#define SIRFSOC_I2C_DATA_MASK(x) (0xFF<<(((x)&3)*8))
#define SIRFSOC_I2C_DATA_SHIFT(x) (((x)&3)*8)
#define SIRFSOC_I2C_DIV_MASK (0xFFFF)
/* I2C status flags */
#define SIRFSOC_I2C_STAT_BUSY BIT(0)
#define SIRFSOC_I2C_STAT_TIP BIT(1)
#define SIRFSOC_I2C_STAT_NACK BIT(2)
#define SIRFSOC_I2C_STAT_TR_INT BIT(4)
#define SIRFSOC_I2C_STAT_STOP BIT(6)
#define SIRFSOC_I2C_STAT_CMD_DONE BIT(8)
#define SIRFSOC_I2C_STAT_ERR BIT(9)
#define SIRFSOC_I2C_CMD_INDEX (0x1F<<16)
/* I2C control flags */
#define SIRFSOC_I2C_RESET BIT(0)
#define SIRFSOC_I2C_CORE_EN BIT(1)
#define SIRFSOC_I2C_MASTER_MODE BIT(2)
#define SIRFSOC_I2C_CMD_DONE_EN BIT(11)
#define SIRFSOC_I2C_ERR_INT_EN BIT(12)
#define SIRFSOC_I2C_SDA_DELAY_MASK (0xFF)
#define SIRFSOC_I2C_SCLF_FILTER (3<<8)
#define SIRFSOC_I2C_START_CMD BIT(0)
#define SIRFSOC_I2C_CMD_RP(x) ((x)&0x7)
#define SIRFSOC_I2C_NACK BIT(3)
#define SIRFSOC_I2C_WRITE BIT(4)
#define SIRFSOC_I2C_READ BIT(5)
#define SIRFSOC_I2C_STOP BIT(6)
#define SIRFSOC_I2C_START BIT(7)
#define SIRFSOC_I2C_DEFAULT_SPEED 100000
#define SIRFSOC_I2C_ERR_NOACK 1
#define SIRFSOC_I2C_ERR_TIMEOUT 2
struct sirfsoc_i2c {
void __iomem *base;
struct clk *clk;
u32 cmd_ptr; /* Current position in CMD buffer */
u8 *buf; /* Buffer passed by user */
u32 msg_len; /* Message length */
u32 finished_len; /* number of bytes read/written */
u32 read_cmd_len; /* number of read cmd sent */
int msg_read; /* 1 indicates a read message */
int err_status; /* 1 indicates an error on bus */
u32 sda_delay; /* For suspend/resume */
u32 clk_div;
int last; /* Last message in transfer, STOP cmd can be sent */
struct completion done; /* indicates completion of message transfer */
struct i2c_adapter adapter;
};
static void i2c_sirfsoc_read_data(struct sirfsoc_i2c *siic)
{
u32 data = 0;
int i;
for (i = 0; i < siic->read_cmd_len; i++) {
if (!(i & 0x3))
data = readl(siic->base + SIRFSOC_I2C_DATA_BUF + i);
siic->buf[siic->finished_len++] =
(u8)((data & SIRFSOC_I2C_DATA_MASK(i)) >>
SIRFSOC_I2C_DATA_SHIFT(i));
}
}
static void i2c_sirfsoc_queue_cmd(struct sirfsoc_i2c *siic)
{
u32 regval;
int i = 0;
if (siic->msg_read) {
while (((siic->finished_len + i) < siic->msg_len)
&& (siic->cmd_ptr < SIRFSOC_I2C_CMD_BUF_MAX)) {
regval = SIRFSOC_I2C_READ | SIRFSOC_I2C_CMD_RP(0);
if (((siic->finished_len + i) ==
(siic->msg_len - 1)) && siic->last)
regval |= SIRFSOC_I2C_STOP | SIRFSOC_I2C_NACK;
writel(regval,
siic->base + SIRFSOC_I2C_CMD(siic->cmd_ptr++));
i++;
}
siic->read_cmd_len = i;
} else {
while ((siic->cmd_ptr < SIRFSOC_I2C_CMD_BUF_MAX - 1)
&& (siic->finished_len < siic->msg_len)) {
regval = SIRFSOC_I2C_WRITE | SIRFSOC_I2C_CMD_RP(0);
if ((siic->finished_len == (siic->msg_len - 1))
&& siic->last)
regval |= SIRFSOC_I2C_STOP;
writel(regval,
siic->base + SIRFSOC_I2C_CMD(siic->cmd_ptr++));
writel(siic->buf[siic->finished_len++],
siic->base + SIRFSOC_I2C_CMD(siic->cmd_ptr++));
}
}
siic->cmd_ptr = 0;
/* Trigger the transfer */
writel(SIRFSOC_I2C_START_CMD, siic->base + SIRFSOC_I2C_CMD_START);
}
static irqreturn_t i2c_sirfsoc_irq(int irq, void *dev_id)
{
struct sirfsoc_i2c *siic = (struct sirfsoc_i2c *)dev_id;
u32 i2c_stat = readl(siic->base + SIRFSOC_I2C_STATUS);
if (i2c_stat & SIRFSOC_I2C_STAT_ERR) {
/* Error conditions */
siic->err_status = SIRFSOC_I2C_ERR_NOACK;
writel(SIRFSOC_I2C_STAT_ERR, siic->base + SIRFSOC_I2C_STATUS);
if (i2c_stat & SIRFSOC_I2C_STAT_NACK)
dev_dbg(&siic->adapter.dev, "ACK not received\n");
else
dev_err(&siic->adapter.dev, "I2C error\n");
/*
* Due to hardware ANOMALY, we need to reset I2C earlier after
* we get NOACK while accessing non-existing clients, otherwise
* we will get errors even we access existing clients later
*/
writel(readl(siic->base + SIRFSOC_I2C_CTRL) | SIRFSOC_I2C_RESET,
siic->base + SIRFSOC_I2C_CTRL);
while (readl(siic->base + SIRFSOC_I2C_CTRL) & SIRFSOC_I2C_RESET)
cpu_relax();
complete(&siic->done);
} else if (i2c_stat & SIRFSOC_I2C_STAT_CMD_DONE) {
/* CMD buffer execution complete */
if (siic->msg_read)
i2c_sirfsoc_read_data(siic);
if (siic->finished_len == siic->msg_len)
complete(&siic->done);
else /* Fill a new CMD buffer for left data */
i2c_sirfsoc_queue_cmd(siic);
writel(SIRFSOC_I2C_STAT_CMD_DONE, siic->base + SIRFSOC_I2C_STATUS);
}
return IRQ_HANDLED;
}
static void i2c_sirfsoc_set_address(struct sirfsoc_i2c *siic,
struct i2c_msg *msg)
{
unsigned char addr;
u32 regval = SIRFSOC_I2C_START | SIRFSOC_I2C_CMD_RP(0) | SIRFSOC_I2C_WRITE;
/* no data and last message -> add STOP */
if (siic->last && (msg->len == 0))
regval |= SIRFSOC_I2C_STOP;
writel(regval, siic->base + SIRFSOC_I2C_CMD(siic->cmd_ptr++));
addr = msg->addr << 1; /* Generate address */
if (msg->flags & I2C_M_RD)
addr |= 1;
/* Reverse direction bit */
if (msg->flags & I2C_M_REV_DIR_ADDR)
addr ^= 1;
writel(addr, siic->base + SIRFSOC_I2C_CMD(siic->cmd_ptr++));
}
static int i2c_sirfsoc_xfer_msg(struct sirfsoc_i2c *siic, struct i2c_msg *msg)
{
u32 regval = readl(siic->base + SIRFSOC_I2C_CTRL);
/* timeout waiting for the xfer to finish or fail */
int timeout = msecs_to_jiffies((msg->len + 1) * 50);
i2c_sirfsoc_set_address(siic, msg);
writel(regval | SIRFSOC_I2C_CMD_DONE_EN | SIRFSOC_I2C_ERR_INT_EN,
siic->base + SIRFSOC_I2C_CTRL);
i2c_sirfsoc_queue_cmd(siic);
if (wait_for_completion_timeout(&siic->done, timeout) == 0) {
siic->err_status = SIRFSOC_I2C_ERR_TIMEOUT;
dev_err(&siic->adapter.dev, "Transfer timeout\n");
}
writel(regval & ~(SIRFSOC_I2C_CMD_DONE_EN | SIRFSOC_I2C_ERR_INT_EN),
siic->base + SIRFSOC_I2C_CTRL);
writel(0, siic->base + SIRFSOC_I2C_CMD_START);
/* i2c control doesn't response, reset it */
if (siic->err_status == SIRFSOC_I2C_ERR_TIMEOUT) {
writel(readl(siic->base + SIRFSOC_I2C_CTRL) | SIRFSOC_I2C_RESET,
siic->base + SIRFSOC_I2C_CTRL);
while (readl(siic->base + SIRFSOC_I2C_CTRL) & SIRFSOC_I2C_RESET)
cpu_relax();
}
return siic->err_status ? -EAGAIN : 0;
}
static u32 i2c_sirfsoc_func(struct i2c_adapter *adap)
{
return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL;
}
static int i2c_sirfsoc_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs,
int num)
{
struct sirfsoc_i2c *siic = adap->algo_data;
int i, ret;
clk_enable(siic->clk);
for (i = 0; i < num; i++) {
siic->buf = msgs[i].buf;
siic->msg_len = msgs[i].len;
siic->msg_read = !!(msgs[i].flags & I2C_M_RD);
siic->err_status = 0;
siic->cmd_ptr = 0;
siic->finished_len = 0;
siic->last = (i == (num - 1));
ret = i2c_sirfsoc_xfer_msg(siic, &msgs[i]);
if (ret) {
clk_disable(siic->clk);
return ret;
}
}
clk_disable(siic->clk);
return num;
}
/* I2C algorithms associated with this master controller driver */
static const struct i2c_algorithm i2c_sirfsoc_algo = {
.master_xfer = i2c_sirfsoc_xfer,
.functionality = i2c_sirfsoc_func,
};
static int i2c_sirfsoc_probe(struct platform_device *pdev)
{
struct sirfsoc_i2c *siic;
struct i2c_adapter *adap;
struct resource *mem_res;
struct clk *clk;
int bitrate;
int ctrl_speed;
int irq;
int err;
u32 regval;
clk = clk_get(&pdev->dev, NULL);
if (IS_ERR(clk)) {
err = PTR_ERR(clk);
dev_err(&pdev->dev, "Clock get failed\n");
goto err_get_clk;
}
err = clk_prepare(clk);
if (err) {
dev_err(&pdev->dev, "Clock prepare failed\n");
goto err_clk_prep;
}
err = clk_enable(clk);
if (err) {
dev_err(&pdev->dev, "Clock enable failed\n");
goto err_clk_en;
}
ctrl_speed = clk_get_rate(clk);
siic = devm_kzalloc(&pdev->dev, sizeof(*siic), GFP_KERNEL);
if (!siic) {
err = -ENOMEM;
goto out;
}
adap = &siic->adapter;
adap->class = I2C_CLASS_DEPRECATED;
mem_res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
siic->base = devm_ioremap_resource(&pdev->dev, mem_res);
if (IS_ERR(siic->base)) {
err = PTR_ERR(siic->base);
goto out;
}
irq = platform_get_irq(pdev, 0);
if (irq < 0) {
err = irq;
goto out;
}
err = devm_request_irq(&pdev->dev, irq, i2c_sirfsoc_irq, 0,
dev_name(&pdev->dev), siic);
if (err)
goto out;
adap->algo = &i2c_sirfsoc_algo;
adap->algo_data = siic;
adap->retries = 3;
adap->dev.of_node = pdev->dev.of_node;
adap->dev.parent = &pdev->dev;
adap->nr = pdev->id;
strlcpy(adap->name, "sirfsoc-i2c", sizeof(adap->name));
platform_set_drvdata(pdev, adap);
init_completion(&siic->done);
/* Controller Initalisation */
writel(SIRFSOC_I2C_RESET, siic->base + SIRFSOC_I2C_CTRL);
while (readl(siic->base + SIRFSOC_I2C_CTRL) & SIRFSOC_I2C_RESET)
cpu_relax();
writel(SIRFSOC_I2C_CORE_EN | SIRFSOC_I2C_MASTER_MODE,
siic->base + SIRFSOC_I2C_CTRL);
siic->clk = clk;
err = of_property_read_u32(pdev->dev.of_node,
"clock-frequency", &bitrate);
if (err < 0)
bitrate = SIRFSOC_I2C_DEFAULT_SPEED;
/*
* Due to some hardware design issues, we need to tune the formula.
* Since i2c is open drain interface that allows the slave to
* stall the transaction by holding the SCL line at '0', the RTL
* implementation is waiting for SCL feedback from the pin after
* setting it to High-Z ('1'). This wait adds to the high-time
* interval counter few cycles of the input synchronization
* (depending on the SCL_FILTER_REG field), and also the time it
* takes for the board pull-up resistor to rise the SCL line.
* For slow SCL settings these additions are negligible,
* but they start to affect the speed when clock is set to faster
* frequencies.
* Through the actual tests, use the different user_div value(which
* in the divider formular 'Fio / (Fi2c * user_div)') to adapt
* the different ranges of i2c bus clock frequency, to make the SCL
* more accurate.
*/
if (bitrate <= 30000)
regval = ctrl_speed / (bitrate * 5);
else if (bitrate > 30000 && bitrate <= 280000)
regval = (2 * ctrl_speed) / (bitrate * 11);
else
regval = ctrl_speed / (bitrate * 6);
writel(regval, siic->base + SIRFSOC_I2C_CLK_CTRL);
if (regval > 0xFF)
writel(0xFF, siic->base + SIRFSOC_I2C_SDA_DELAY);
else
writel(regval, siic->base + SIRFSOC_I2C_SDA_DELAY);
err = i2c_add_numbered_adapter(adap);
if (err < 0) {
dev_err(&pdev->dev, "Can't add new i2c adapter\n");
goto out;
}
clk_disable(clk);
dev_info(&pdev->dev, " I2C adapter ready to operate\n");
return 0;
out:
clk_disable(clk);
err_clk_en:
clk_unprepare(clk);
err_clk_prep:
clk_put(clk);
err_get_clk:
return err;
}
static int i2c_sirfsoc_remove(struct platform_device *pdev)
{
struct i2c_adapter *adapter = platform_get_drvdata(pdev);
struct sirfsoc_i2c *siic = adapter->algo_data;
writel(SIRFSOC_I2C_RESET, siic->base + SIRFSOC_I2C_CTRL);
i2c_del_adapter(adapter);
clk_unprepare(siic->clk);
clk_put(siic->clk);
return 0;
}
#ifdef CONFIG_PM
static int i2c_sirfsoc_suspend(struct device *dev)
{
struct platform_device *pdev = to_platform_device(dev);
struct i2c_adapter *adapter = platform_get_drvdata(pdev);
struct sirfsoc_i2c *siic = adapter->algo_data;
clk_enable(siic->clk);
siic->sda_delay = readl(siic->base + SIRFSOC_I2C_SDA_DELAY);
siic->clk_div = readl(siic->base + SIRFSOC_I2C_CLK_CTRL);
clk_disable(siic->clk);
return 0;
}
static int i2c_sirfsoc_resume(struct device *dev)
{
struct platform_device *pdev = to_platform_device(dev);
struct i2c_adapter *adapter = platform_get_drvdata(pdev);
struct sirfsoc_i2c *siic = adapter->algo_data;
clk_enable(siic->clk);
writel(SIRFSOC_I2C_RESET, siic->base + SIRFSOC_I2C_CTRL);
while (readl(siic->base + SIRFSOC_I2C_CTRL) & SIRFSOC_I2C_RESET)
cpu_relax();
writel(SIRFSOC_I2C_CORE_EN | SIRFSOC_I2C_MASTER_MODE,
siic->base + SIRFSOC_I2C_CTRL);
writel(siic->clk_div, siic->base + SIRFSOC_I2C_CLK_CTRL);
writel(siic->sda_delay, siic->base + SIRFSOC_I2C_SDA_DELAY);
clk_disable(siic->clk);
return 0;
}
static const struct dev_pm_ops i2c_sirfsoc_pm_ops = {
.suspend = i2c_sirfsoc_suspend,
.resume = i2c_sirfsoc_resume,
};
#endif
static const struct of_device_id sirfsoc_i2c_of_match[] = {
{ .compatible = "sirf,prima2-i2c", },
{},
};
MODULE_DEVICE_TABLE(of, sirfsoc_i2c_of_match);
static struct platform_driver i2c_sirfsoc_driver = {
.driver = {
.name = "sirfsoc_i2c",
#ifdef CONFIG_PM
.pm = &i2c_sirfsoc_pm_ops,
#endif
.of_match_table = sirfsoc_i2c_of_match,
},
.probe = i2c_sirfsoc_probe,
.remove = i2c_sirfsoc_remove,
};
module_platform_driver(i2c_sirfsoc_driver);
MODULE_DESCRIPTION("SiRF SoC I2C master controller driver");
MODULE_AUTHOR("Zhiwu Song <Zhiwu.Song@csr.com>, "
"Xiangzhen Ye <Xiangzhen.Ye@csr.com>");
MODULE_LICENSE("GPL v2");