- 根目录:
- drivers
- i2c
- busses
- i2c-kempld.c
/*
* I2C bus driver for Kontron COM modules
*
* Copyright (c) 2010-2013 Kontron Europe GmbH
* Author: Michael Brunner <michael.brunner@kontron.com>
*
* The driver is based on the i2c-ocores driver by Peter Korsgaard.
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License 2 as published
* by the Free Software Foundation.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*/
#include <linux/module.h>
#include <linux/platform_device.h>
#include <linux/i2c.h>
#include <linux/delay.h>
#include <linux/mfd/kempld.h>
#define KEMPLD_I2C_PRELOW 0x0b
#define KEMPLD_I2C_PREHIGH 0x0c
#define KEMPLD_I2C_DATA 0x0e
#define KEMPLD_I2C_CTRL 0x0d
#define I2C_CTRL_IEN 0x40
#define I2C_CTRL_EN 0x80
#define KEMPLD_I2C_STAT 0x0f
#define I2C_STAT_IF 0x01
#define I2C_STAT_TIP 0x02
#define I2C_STAT_ARBLOST 0x20
#define I2C_STAT_BUSY 0x40
#define I2C_STAT_NACK 0x80
#define KEMPLD_I2C_CMD 0x0f
#define I2C_CMD_START 0x91
#define I2C_CMD_STOP 0x41
#define I2C_CMD_READ 0x21
#define I2C_CMD_WRITE 0x11
#define I2C_CMD_READ_ACK 0x21
#define I2C_CMD_READ_NACK 0x29
#define I2C_CMD_IACK 0x01
#define KEMPLD_I2C_FREQ_MAX 2700 /* 2.7 mHz */
#define KEMPLD_I2C_FREQ_STD 100 /* 100 kHz */
enum {
STATE_DONE = 0,
STATE_INIT,
STATE_ADDR,
STATE_ADDR10,
STATE_START,
STATE_WRITE,
STATE_READ,
STATE_ERROR,
};
struct kempld_i2c_data {
struct device *dev;
struct kempld_device_data *pld;
struct i2c_adapter adap;
struct i2c_msg *msg;
int pos;
int nmsgs;
int state;
bool was_active;
};
static unsigned int bus_frequency = KEMPLD_I2C_FREQ_STD;
module_param(bus_frequency, uint, 0);
MODULE_PARM_DESC(bus_frequency, "Set I2C bus frequency in kHz (default="
__MODULE_STRING(KEMPLD_I2C_FREQ_STD)")");
static int i2c_bus = -1;
module_param(i2c_bus, int, 0);
MODULE_PARM_DESC(i2c_bus, "Set I2C bus number (default=-1 for dynamic assignment)");
static bool i2c_gpio_mux;
module_param(i2c_gpio_mux, bool, 0);
MODULE_PARM_DESC(i2c_gpio_mux, "Enable I2C port on GPIO out (default=false)");
/*
* kempld_get_mutex must be called prior to calling this function.
*/
static int kempld_i2c_process(struct kempld_i2c_data *i2c)
{
struct kempld_device_data *pld = i2c->pld;
u8 stat = kempld_read8(pld, KEMPLD_I2C_STAT);
struct i2c_msg *msg = i2c->msg;
u8 addr;
/* Ready? */
if (stat & I2C_STAT_TIP)
return -EBUSY;
if (i2c->state == STATE_DONE || i2c->state == STATE_ERROR) {
/* Stop has been sent */
kempld_write8(pld, KEMPLD_I2C_CMD, I2C_CMD_IACK);
if (i2c->state == STATE_ERROR)
return -EIO;
return 0;
}
/* Error? */
if (stat & I2C_STAT_ARBLOST) {
i2c->state = STATE_ERROR;
kempld_write8(pld, KEMPLD_I2C_CMD, I2C_CMD_STOP);
return -EAGAIN;
}
if (i2c->state == STATE_INIT) {
if (stat & I2C_STAT_BUSY)
return -EBUSY;
i2c->state = STATE_ADDR;
}
if (i2c->state == STATE_ADDR) {
/* 10 bit address? */
if (i2c->msg->flags & I2C_M_TEN) {
addr = 0xf0 | ((i2c->msg->addr >> 7) & 0x6);
i2c->state = STATE_ADDR10;
} else {
addr = (i2c->msg->addr << 1);
i2c->state = STATE_START;
}
/* Set read bit if necessary */
addr |= (i2c->msg->flags & I2C_M_RD) ? 1 : 0;
kempld_write8(pld, KEMPLD_I2C_DATA, addr);
kempld_write8(pld, KEMPLD_I2C_CMD, I2C_CMD_START);
return 0;
}
/* Second part of 10 bit addressing */
if (i2c->state == STATE_ADDR10) {
kempld_write8(pld, KEMPLD_I2C_DATA, i2c->msg->addr & 0xff);
kempld_write8(pld, KEMPLD_I2C_CMD, I2C_CMD_WRITE);
i2c->state = STATE_START;
return 0;
}
if (i2c->state == STATE_START || i2c->state == STATE_WRITE) {
i2c->state = (msg->flags & I2C_M_RD) ? STATE_READ : STATE_WRITE;
if (stat & I2C_STAT_NACK) {
i2c->state = STATE_ERROR;
kempld_write8(pld, KEMPLD_I2C_CMD, I2C_CMD_STOP);
return -ENXIO;
}
} else {
msg->buf[i2c->pos++] = kempld_read8(pld, KEMPLD_I2C_DATA);
}
if (i2c->pos >= msg->len) {
i2c->nmsgs--;
i2c->msg++;
i2c->pos = 0;
msg = i2c->msg;
if (i2c->nmsgs) {
if (!(msg->flags & I2C_M_NOSTART)) {
i2c->state = STATE_ADDR;
return 0;
} else {
i2c->state = (msg->flags & I2C_M_RD)
? STATE_READ : STATE_WRITE;
}
} else {
i2c->state = STATE_DONE;
kempld_write8(pld, KEMPLD_I2C_CMD, I2C_CMD_STOP);
return 0;
}
}
if (i2c->state == STATE_READ) {
kempld_write8(pld, KEMPLD_I2C_CMD, i2c->pos == (msg->len - 1) ?
I2C_CMD_READ_NACK : I2C_CMD_READ_ACK);
} else {
kempld_write8(pld, KEMPLD_I2C_DATA, msg->buf[i2c->pos++]);
kempld_write8(pld, KEMPLD_I2C_CMD, I2C_CMD_WRITE);
}
return 0;
}
static int kempld_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs,
int num)
{
struct kempld_i2c_data *i2c = i2c_get_adapdata(adap);
struct kempld_device_data *pld = i2c->pld;
unsigned long timeout = jiffies + HZ;
int ret;
i2c->msg = msgs;
i2c->pos = 0;
i2c->nmsgs = num;
i2c->state = STATE_INIT;
/* Handle the transfer */
while (time_before(jiffies, timeout)) {
kempld_get_mutex(pld);
ret = kempld_i2c_process(i2c);
kempld_release_mutex(pld);
if (i2c->state == STATE_DONE || i2c->state == STATE_ERROR)
return (i2c->state == STATE_DONE) ? num : ret;
if (ret == 0)
timeout = jiffies + HZ;
usleep_range(5, 15);
}
i2c->state = STATE_ERROR;
return -ETIMEDOUT;
}
/*
* kempld_get_mutex must be called prior to calling this function.
*/
static void kempld_i2c_device_init(struct kempld_i2c_data *i2c)
{
struct kempld_device_data *pld = i2c->pld;
u16 prescale_corr;
long prescale;
u8 ctrl;
u8 stat;
u8 cfg;
/* Make sure the device is disabled */
ctrl = kempld_read8(pld, KEMPLD_I2C_CTRL);
ctrl &= ~(I2C_CTRL_EN | I2C_CTRL_IEN);
kempld_write8(pld, KEMPLD_I2C_CTRL, ctrl);
if (bus_frequency > KEMPLD_I2C_FREQ_MAX)
bus_frequency = KEMPLD_I2C_FREQ_MAX;
if (pld->info.spec_major == 1)
prescale = pld->pld_clock / (bus_frequency * 5) - 1000;
else
prescale = pld->pld_clock / (bus_frequency * 4) - 3000;
if (prescale < 0)
prescale = 0;
/* Round to the best matching value */
prescale_corr = prescale / 1000;
if (prescale % 1000 >= 500)
prescale_corr++;
kempld_write8(pld, KEMPLD_I2C_PRELOW, prescale_corr & 0xff);
kempld_write8(pld, KEMPLD_I2C_PREHIGH, prescale_corr >> 8);
/* Activate I2C bus output on GPIO pins */
cfg = kempld_read8(pld, KEMPLD_CFG);
if (i2c_gpio_mux)
cfg |= KEMPLD_CFG_GPIO_I2C_MUX;
else
cfg &= ~KEMPLD_CFG_GPIO_I2C_MUX;
kempld_write8(pld, KEMPLD_CFG, cfg);
/* Enable the device */
kempld_write8(pld, KEMPLD_I2C_CMD, I2C_CMD_IACK);
ctrl |= I2C_CTRL_EN;
kempld_write8(pld, KEMPLD_I2C_CTRL, ctrl);
stat = kempld_read8(pld, KEMPLD_I2C_STAT);
if (stat & I2C_STAT_BUSY)
kempld_write8(pld, KEMPLD_I2C_CMD, I2C_CMD_STOP);
}
static u32 kempld_i2c_func(struct i2c_adapter *adap)
{
return I2C_FUNC_I2C | I2C_FUNC_10BIT_ADDR | I2C_FUNC_SMBUS_EMUL;
}
static const struct i2c_algorithm kempld_i2c_algorithm = {
.master_xfer = kempld_i2c_xfer,
.functionality = kempld_i2c_func,
};
static struct i2c_adapter kempld_i2c_adapter = {
.owner = THIS_MODULE,
.name = "i2c-kempld",
.class = I2C_CLASS_HWMON | I2C_CLASS_SPD,
.algo = &kempld_i2c_algorithm,
};
static int kempld_i2c_probe(struct platform_device *pdev)
{
struct kempld_device_data *pld = dev_get_drvdata(pdev->dev.parent);
struct kempld_i2c_data *i2c;
int ret;
u8 ctrl;
i2c = devm_kzalloc(&pdev->dev, sizeof(*i2c), GFP_KERNEL);
if (!i2c)
return -ENOMEM;
i2c->pld = pld;
i2c->dev = &pdev->dev;
i2c->adap = kempld_i2c_adapter;
i2c->adap.dev.parent = i2c->dev;
i2c_set_adapdata(&i2c->adap, i2c);
platform_set_drvdata(pdev, i2c);
kempld_get_mutex(pld);
ctrl = kempld_read8(pld, KEMPLD_I2C_CTRL);
if (ctrl & I2C_CTRL_EN)
i2c->was_active = true;
kempld_i2c_device_init(i2c);
kempld_release_mutex(pld);
/* Add I2C adapter to I2C tree */
if (i2c_bus >= -1)
i2c->adap.nr = i2c_bus;
ret = i2c_add_numbered_adapter(&i2c->adap);
if (ret)
return ret;
dev_info(i2c->dev, "I2C bus initialized at %dkHz\n",
bus_frequency);
return 0;
}
static int kempld_i2c_remove(struct platform_device *pdev)
{
struct kempld_i2c_data *i2c = platform_get_drvdata(pdev);
struct kempld_device_data *pld = i2c->pld;
u8 ctrl;
kempld_get_mutex(pld);
/*
* Disable I2C logic if it was not activated before the
* driver loaded
*/
if (!i2c->was_active) {
ctrl = kempld_read8(pld, KEMPLD_I2C_CTRL);
ctrl &= ~I2C_CTRL_EN;
kempld_write8(pld, KEMPLD_I2C_CTRL, ctrl);
}
kempld_release_mutex(pld);
i2c_del_adapter(&i2c->adap);
return 0;
}
#ifdef CONFIG_PM
static int kempld_i2c_suspend(struct platform_device *pdev, pm_message_t state)
{
struct kempld_i2c_data *i2c = platform_get_drvdata(pdev);
struct kempld_device_data *pld = i2c->pld;
u8 ctrl;
kempld_get_mutex(pld);
ctrl = kempld_read8(pld, KEMPLD_I2C_CTRL);
ctrl &= ~I2C_CTRL_EN;
kempld_write8(pld, KEMPLD_I2C_CTRL, ctrl);
kempld_release_mutex(pld);
return 0;
}
static int kempld_i2c_resume(struct platform_device *pdev)
{
struct kempld_i2c_data *i2c = platform_get_drvdata(pdev);
struct kempld_device_data *pld = i2c->pld;
kempld_get_mutex(pld);
kempld_i2c_device_init(i2c);
kempld_release_mutex(pld);
return 0;
}
#else
#define kempld_i2c_suspend NULL
#define kempld_i2c_resume NULL
#endif
static struct platform_driver kempld_i2c_driver = {
.driver = {
.name = "kempld-i2c",
},
.probe = kempld_i2c_probe,
.remove = kempld_i2c_remove,
.suspend = kempld_i2c_suspend,
.resume = kempld_i2c_resume,
};
module_platform_driver(kempld_i2c_driver);
MODULE_DESCRIPTION("KEM PLD I2C Driver");
MODULE_AUTHOR("Michael Brunner <michael.brunner@kontron.com>");
MODULE_LICENSE("GPL");
MODULE_ALIAS("platform:kempld_i2c");