OpenWrt – Rev 4
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/*
* Cavium CNS3xxx I2C Host Controller
*
* Copyright 2010 Cavium Network
* Copyright 2012 Gateworks Corporation
* Chris Lang <clang@gateworks.com>
* Tim Harvey <tharvey@gateworks.com>
*
* This file is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License, Version 2, as
* published by the Free Software Foundation.
*/
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/init.h>
#include <linux/platform_device.h>
#include <asm/io.h>
#include <linux/wait.h>
#include <linux/interrupt.h>
#include <linux/delay.h>
#include <linux/i2c.h>
#include <linux/slab.h>
#include <linux/clk.h>
/*
* We need the memory map
*/
#define I2C_MEM_MAP_ADDR(x) (i2c->base + x)
#define I2C_MEM_MAP_VALUE(x) (*((unsigned int volatile*)I2C_MEM_MAP_ADDR(x)))
#define I2C_CONTROLLER_REG I2C_MEM_MAP_VALUE(0x00)
#define I2C_TIME_OUT_REG I2C_MEM_MAP_VALUE(0x04)
#define I2C_SLAVE_ADDRESS_REG I2C_MEM_MAP_VALUE(0x08)
#define I2C_WRITE_DATA_REG I2C_MEM_MAP_VALUE(0x0C)
#define I2C_READ_DATA_REG I2C_MEM_MAP_VALUE(0x10)
#define I2C_INTERRUPT_STATUS_REG I2C_MEM_MAP_VALUE(0x14)
#define I2C_INTERRUPT_ENABLE_REG I2C_MEM_MAP_VALUE(0x18)
#define I2C_TWI_OUT_DLY_REG I2C_MEM_MAP_VALUE(0x1C)
#define I2C_BUS_ERROR_FLAG (0x1)
#define I2C_ACTION_DONE_FLAG (0x2)
#define CNS3xxx_I2C_ENABLE() (I2C_CONTROLLER_REG) |= ((unsigned int)0x1 << 31)
#define CNS3xxx_I2C_DISABLE() (I2C_CONTROLLER_REG) &= ~((unsigned int)0x1 << 31)
#define CNS3xxx_I2C_ENABLE_INTR() (I2C_INTERRUPT_ENABLE_REG) |= 0x03
#define CNS3xxx_I2C_DISABLE_INTR() (I2C_INTERRUPT_ENABLE_REG) &= 0xfc
#define TWI_TIMEOUT (10*HZ)
#define I2C_100KHZ 100000
#define I2C_200KHZ 200000
#define I2C_300KHZ 300000
#define I2C_400KHZ 400000
#define CNS3xxx_I2C_CLK I2C_100KHZ
#define STATE_DONE 1
#define STATE_ERROR 2
struct cns3xxx_i2c {
struct device *dev;
void __iomem *base; /* virtual */
wait_queue_head_t wait;
struct i2c_adapter adap;
struct i2c_msg *msg;
u8 state; /* see STATE_ */
u8 error; /* see TWI_STATUS register */
int rd_wr_len;
u8 *buf;
};
static u32 cns3xxx_i2c_func(struct i2c_adapter *adap)
{
return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL;
}
static int
cns3xxx_i2c_xfer_msg(struct i2c_adapter *adap, struct i2c_msg *msg)
{
struct cns3xxx_i2c *i2c = i2c_get_adapdata(adap);
int i, j;
u8 buf[1] = { 0 };
if (msg->len == 0) {
/*
* We are probably doing a probe for a device here,
* so set the length to one, and data to 0
*/
msg->len = 1;
i2c->buf = buf;
} else {
i2c->buf = msg->buf;
}
if (msg->flags & I2C_M_TEN) {
printk
("%s:%d: Presently the driver does not handle extended addressing\n",
__FUNCTION__, __LINE__);
return -EINVAL;
}
i2c->msg = msg;
for (i = 0; i < msg->len; i++) {
if (msg->len - i >= 4)
i2c->rd_wr_len = 3;
else
i2c->rd_wr_len = msg->len - i - 1;
// Set Data Width and TWI_EN
I2C_CONTROLLER_REG = 0x80000000 | (i2c->rd_wr_len << 2) | (i2c->rd_wr_len);
// Clear Write Reg
I2C_WRITE_DATA_REG = 0;
// Set the slave address
I2C_SLAVE_ADDRESS_REG = (msg->addr << 1);
// Are we Writing
if (!(msg->flags & I2C_M_RD)) {
I2C_CONTROLLER_REG |= (1 << 4);
if (i != 0) {
/*
* We need to set the address in the first byte.
* The base address is going to be in buf[0] and then
* it needs to be incremented by i - 1.
*/
i2c->buf--;
*i2c->buf = buf[0] + i - 1;
if (i2c->rd_wr_len < 3) {
i += i2c->rd_wr_len;
i2c->rd_wr_len++;
I2C_CONTROLLER_REG = 0x80000000 | (1 << 4) | (i2c->rd_wr_len << 2) | (i2c->rd_wr_len);
} else {
i += i2c->rd_wr_len - 1;
}
} else {
i += i2c->rd_wr_len;
buf[0] = *i2c->buf;
}
for (j = 0; j <= i2c->rd_wr_len; j++) {
I2C_WRITE_DATA_REG |= ((*i2c->buf++) << (8 * j));
}
} else {
i += i2c->rd_wr_len;
}
// Start the Transfer
i2c->state = 0; // Clear out the State
i2c->error = 0;
I2C_CONTROLLER_REG |= (1 << 6);
if (wait_event_timeout(i2c->wait, (i2c->state == STATE_ERROR) ||
(i2c->state == STATE_DONE), TWI_TIMEOUT)) {
if (i2c->state == STATE_ERROR) {
dev_dbg(i2c->dev, "controller error: 0x%2x", i2c->error);
return -EAGAIN; // try again
}
} else {
dev_err(i2c->dev, "controller timed out "
"waiting for start condition to finish\n");
return -ETIMEDOUT;
}
}
return 0;
}
static int
cns3xxx_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs, int num)
{
int i;
int ret;
for (i = 0; i < num; i++)
{
ret = cns3xxx_i2c_xfer_msg(adap, &msgs[i]);
if (ret < 0) {
return ret;
}
}
return num;
}
static struct i2c_algorithm cns3xxx_i2c_algo = {
.master_xfer = cns3xxx_i2c_xfer,
.functionality = cns3xxx_i2c_func,
};
static struct i2c_adapter cns3xxx_i2c_adapter = {
.owner = THIS_MODULE,
.algo = &cns3xxx_i2c_algo,
.algo_data = NULL,
.nr = 0,
.name = "CNS3xxx I2C 0",
.retries = 5,
};
static void cns3xxx_i2c_adapter_init(struct cns3xxx_i2c *i2c)
{
struct clk *clk;
clk = devm_clk_get(i2c->dev, "cpu");
if (WARN_ON(!clk))
return;
/* Disable the I2C */
I2C_CONTROLLER_REG = 0; /* Disabled the I2C */
/* Check the Reg Dump when testing */
I2C_TIME_OUT_REG =
(((((clk_get_rate(clk) / (2 * CNS3xxx_I2C_CLK)) -
1) & 0x3FF) << 8) | (1 << 7) | 0x7F);
I2C_TWI_OUT_DLY_REG |= 0x3;
/* Enable The Interrupt */
CNS3xxx_I2C_ENABLE_INTR();
/* Clear Interrupt Status (0x2 | 0x1) */
I2C_INTERRUPT_STATUS_REG |= (I2C_ACTION_DONE_FLAG | I2C_BUS_ERROR_FLAG);
/* Enable the I2C Controller */
CNS3xxx_I2C_ENABLE();
}
static irqreturn_t cns3xxx_i2c_isr(int irq, void *dev_id)
{
struct cns3xxx_i2c *i2c = dev_id;
int i;
uint32_t stat = I2C_INTERRUPT_STATUS_REG;
/* Clear Interrupt */
I2C_INTERRUPT_STATUS_REG |= 0x1;
if (stat & I2C_BUS_ERROR_FLAG) {
i2c->state = STATE_ERROR;
i2c->error = (I2C_INTERRUPT_STATUS_REG & 0xff00)>>8;
} else {
if (i2c->msg->flags & I2C_M_RD) {
for (i = 0; i <= i2c->rd_wr_len; i++)
{
*i2c->buf++ = ((I2C_READ_DATA_REG >> (8 * i)) & 0xff);
}
}
i2c->state = STATE_DONE;
}
wake_up(&i2c->wait);
return IRQ_HANDLED;
}
static int cns3xxx_i2c_probe(struct platform_device *pdev)
{
struct cns3xxx_i2c *i2c;
struct resource *res, *res2;
int ret;
res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
if (!res) {
printk("%s: IORESOURCE_MEM not defined \n", __FUNCTION__);
return -ENODEV;
}
res2 = platform_get_resource(pdev, IORESOURCE_IRQ, 0);
if (!res2) {
printk("%s: IORESOURCE_IRQ not defined \n", __FUNCTION__);
return -ENODEV;
}
i2c = kzalloc(sizeof(*i2c), GFP_KERNEL);
if (!i2c)
return -ENOMEM;
if (!request_mem_region(res->start, res->end - res->start + 1,
pdev->name)) {
dev_err(&pdev->dev, "Memory region busy\n");
ret = -EBUSY;
goto request_mem_failed;
}
i2c->dev = &pdev->dev;
i2c->base = ioremap(res->start, res->end - res->start + 1);
if (!i2c->base) {
dev_err(&pdev->dev, "Unable to map registers\n");
ret = -EIO;
goto map_failed;
}
cns3xxx_i2c_adapter_init(i2c);
init_waitqueue_head(&i2c->wait);
ret = request_irq(res2->start, cns3xxx_i2c_isr, 0, pdev->name, i2c);
if (ret) {
dev_err(&pdev->dev, "Cannot claim IRQ\n");
goto request_irq_failed;
}
platform_set_drvdata(pdev, i2c);
i2c->adap = cns3xxx_i2c_adapter;
i2c_set_adapdata(&i2c->adap, i2c);
i2c->adap.dev.parent = &pdev->dev;
/* add i2c adapter to i2c tree */
ret = i2c_add_numbered_adapter(&i2c->adap);
if (ret) {
dev_err(&pdev->dev, "Failed to add adapter\n");
goto add_adapter_failed;
}
return 0;
add_adapter_failed:
free_irq(res2->start, i2c);
request_irq_failed:
iounmap(i2c->base);
map_failed:
release_mem_region(res->start, res->end - res->start + 1);
request_mem_failed:
kfree(i2c);
return ret;
}
static int cns3xxx_i2c_remove(struct platform_device *pdev)
{
struct cns3xxx_i2c *i2c = platform_get_drvdata(pdev);
struct resource *res;
/* disable i2c logic */
CNS3xxx_I2C_DISABLE_INTR();
CNS3xxx_I2C_DISABLE();
/* remove adapter & data */
i2c_del_adapter(&i2c->adap);
platform_set_drvdata(pdev, NULL);
res = platform_get_resource(pdev, IORESOURCE_IRQ, 0);
if (res)
free_irq(res->start, i2c);
iounmap(i2c->base);
res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
if (res)
release_mem_region(res->start, res->end - res->start + 1);
kfree(i2c);
return 0;
}
static struct platform_driver cns3xxx_i2c_driver = {
.probe = cns3xxx_i2c_probe,
.remove = cns3xxx_i2c_remove,
.driver = {
.owner = THIS_MODULE,
.name = "cns3xxx-i2c",
},
};
static int __init cns3xxx_i2c_init(void)
{
return platform_driver_register(&cns3xxx_i2c_driver);
}
static void __exit cns3xxx_i2c_exit(void)
{
platform_driver_unregister(&cns3xxx_i2c_driver);
}
module_init(cns3xxx_i2c_init);
module_exit(cns3xxx_i2c_exit);
MODULE_AUTHOR("Cavium Networks");
MODULE_DESCRIPTION("Cavium CNS3XXX I2C Controller");
MODULE_LICENSE("GPL");