- 根目录:
- drivers
- i2c
- busses
- i2c-nuc900.c
/*
* linux/drivers/i2c/busses/i2c-nuc900.c
*
* Copyright (c) 2010 Nuvoton technology corporation.
*
* This driver based on S3C2410 I2C driver of Ben Dooks <ben-Y5A6D6n0/KfQXOPxS62xeg@public.gmane.org>.
* Written by Wan ZongShun <mcuos.com-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation;version 2 of the License.
*
*/
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/i2c.h>
#include <linux/init.h>
#include <linux/time.h>
#include <linux/interrupt.h>
#include <linux/delay.h>
#include <linux/errno.h>
#include <linux/err.h>
#include <linux/platform_device.h>
#include <linux/clk.h>
#include <linux/cpufreq.h>
#include <linux/slab.h>
#include <linux/io.h>
#include <mach/mfp.h>
#include <linux/platform_data/i2c-nuc900.h>
/* nuc900 i2c registers offset */
#define CSR 0x00
#define DIVIDER 0x04
#define CMDR 0x08
#define SWR 0x0C
#define RXR 0x10
#define TXR 0x14
/* nuc900 i2c CSR register bits */
#define IRQEN 0x003
#define I2CBUSY 0x400
#define I2CSTART 0x018
#define IRQFLAG 0x004
#define ARBIT_LOST 0x200
#define SLAVE_ACK 0x800
/* nuc900 i2c CMDR register bits */
#define I2C_CMD_START 0x10
#define I2C_CMD_STOP 0x08
#define I2C_CMD_READ 0x04
#define I2C_CMD_WRITE 0x02
#define I2C_CMD_NACK 0x01
/* i2c controller state */
enum nuc900_i2c_state {
STATE_IDLE,
STATE_START,
STATE_READ,
STATE_WRITE,
STATE_STOP
};
/* i2c controller private data */
struct nuc900_i2c {
spinlock_t lock;
wait_queue_head_t wait;
struct i2c_msg *msg;
unsigned int msg_num;
unsigned int msg_idx;
unsigned int msg_ptr;
unsigned int irq;
enum nuc900_i2c_state state;
void __iomem *regs;
struct clk *clk;
struct device *dev;
struct resource *ioarea;
struct i2c_adapter adap;
};
/* nuc900_i2c_master_complete
*
* complete the message and wake up the caller, using the given return code,
* or zero to mean ok.
*/
static inline void nuc900_i2c_master_complete(struct nuc900_i2c *i2c, int ret)
{
dev_dbg(i2c->dev, "master_complete %d\n", ret);
i2c->msg_ptr = 0;
i2c->msg = NULL;
i2c->msg_idx++;
i2c->msg_num = 0;
if (ret)
i2c->msg_idx = ret;
wake_up(&i2c->wait);
}
/* irq enable/disable functions */
static inline void nuc900_i2c_disable_irq(struct nuc900_i2c *i2c)
{
unsigned long tmp;
tmp = readl(i2c->regs + CSR);
writel(tmp & ~IRQEN, i2c->regs + CSR);
}
static inline void nuc900_i2c_enable_irq(struct nuc900_i2c *i2c)
{
unsigned long tmp;
tmp = readl(i2c->regs + CSR);
writel(tmp | IRQEN, i2c->regs + CSR);
}
/* nuc900_i2c_message_start
*
* put the start of a message onto the bus
*/
static void nuc900_i2c_message_start(struct nuc900_i2c *i2c,
struct i2c_msg *msg)
{
unsigned int addr = (msg->addr & 0x7f) << 1;
if (msg->flags & I2C_M_RD)
addr |= 0x1;
writel(addr & 0xff, i2c->regs + TXR);
writel(I2C_CMD_START | I2C_CMD_WRITE, i2c->regs + CMDR);
}
static inline void nuc900_i2c_stop(struct nuc900_i2c *i2c, int ret)
{
dev_dbg(i2c->dev, "STOP\n");
/* stop the transfer */
i2c->state = STATE_STOP;
writel(I2C_CMD_STOP, i2c->regs + CMDR);
nuc900_i2c_master_complete(i2c, ret);
nuc900_i2c_disable_irq(i2c);
}
/* helper functions to determine the current state in the set of
* messages we are sending
*/
/* is_lastmsg()
*
* returns TRUE if the current message is the last in the set
*/
static inline int is_lastmsg(struct nuc900_i2c *i2c)
{
return i2c->msg_idx >= (i2c->msg_num - 1);
}
/* is_msglast
*
* returns TRUE if we this is the last byte in the current message
*/
static inline int is_msglast(struct nuc900_i2c *i2c)
{
return i2c->msg_ptr == i2c->msg->len-1;
}
/* is_msgend
*
* returns TRUE if we reached the end of the current message
*/
static inline int is_msgend(struct nuc900_i2c *i2c)
{
return i2c->msg_ptr >= i2c->msg->len;
}
/* i2c_nuc900_irq_nextbyte
*
* process an interrupt and work out what to do
*/
static void i2c_nuc900_irq_nextbyte(struct nuc900_i2c *i2c,
unsigned long iicstat)
{
unsigned char byte;
switch (i2c->state) {
case STATE_IDLE:
dev_err(i2c->dev, "%s: called in STATE_IDLE\n", __func__);
break;
case STATE_STOP:
dev_err(i2c->dev, "%s: called in STATE_STOP\n", __func__);
nuc900_i2c_disable_irq(i2c);
break;
case STATE_START:
/* last thing we did was send a start condition on the
* bus, or started a new i2c message
*/
if (iicstat & SLAVE_ACK &&
!(i2c->msg->flags & I2C_M_IGNORE_NAK)) {
/* ack was not received... */
dev_dbg(i2c->dev, "ack was not received\n");
nuc900_i2c_stop(i2c, -ENXIO);
break;
}
if (i2c->msg->flags & I2C_M_RD)
i2c->state = STATE_READ;
else
i2c->state = STATE_WRITE;
/* terminate the transfer if there is nothing to do
* as this is used by the i2c probe to find devices.
*/
if (is_lastmsg(i2c) && i2c->msg->len == 0) {
nuc900_i2c_stop(i2c, 0);
break;
}
if (i2c->state == STATE_READ)
goto prepare_read;
/* fall through to the write state, as we will need to
* send a byte as well
*/
case STATE_WRITE:
/* we are writing data to the device... check for the
* end of the message, and if so, work out what to do
*/
if (!(i2c->msg->flags & I2C_M_IGNORE_NAK)) {
if (iicstat & SLAVE_ACK) {
dev_dbg(i2c->dev, "WRITE: No Ack\n");
nuc900_i2c_stop(i2c, -ECONNREFUSED);
break;
}
}
retry_write:
if (!is_msgend(i2c)) {
byte = i2c->msg->buf[i2c->msg_ptr++];
writeb(byte, i2c->regs + TXR);
writel(I2C_CMD_WRITE, i2c->regs + CMDR);
} else if (!is_lastmsg(i2c)) {
/* we need to go to the next i2c message */
dev_dbg(i2c->dev, "WRITE: Next Message\n");
i2c->msg_ptr = 0;
i2c->msg_idx++;
i2c->msg++;
/* check to see if we need to do another message */
if (i2c->msg->flags & I2C_M_NOSTART) {
if (i2c->msg->flags & I2C_M_RD) {
/* cannot do this, the controller
* forces us to send a new START
* when we change direction
*/
nuc900_i2c_stop(i2c, -EINVAL);
}
goto retry_write;
} else {
/* send the new start */
nuc900_i2c_message_start(i2c, i2c->msg);
i2c->state = STATE_START;
}
} else {
/* send stop */
nuc900_i2c_stop(i2c, 0);
}
break;
case STATE_READ:
/* we have a byte of data in the data register, do
* something with it, and then work out whether we are
* going to do any more read/write
*/
byte = readb(i2c->regs + RXR);
i2c->msg->buf[i2c->msg_ptr++] = byte;
prepare_read:
if (is_msglast(i2c)) {
/* last byte of buffer */
if (is_lastmsg(i2c))
writel(I2C_CMD_READ | I2C_CMD_NACK,
i2c->regs + CMDR);
} else if (is_msgend(i2c)) {
/* ok, we've read the entire buffer, see if there
* is anything else we need to do
*/
if (is_lastmsg(i2c)) {
/* last message, send stop and complete */
dev_dbg(i2c->dev, "READ: Send Stop\n");
nuc900_i2c_stop(i2c, 0);
} else {
/* go to the next transfer */
dev_dbg(i2c->dev, "READ: Next Transfer\n");
i2c->msg_ptr = 0;
i2c->msg_idx++;
i2c->msg++;
writel(I2C_CMD_READ, i2c->regs + CMDR);
}
} else {
writel(I2C_CMD_READ, i2c->regs + CMDR);
}
break;
}
}
/* nuc900_i2c_irq
*
* top level IRQ servicing routine
*/
static irqreturn_t nuc900_i2c_irq(int irqno, void *dev_id)
{
struct nuc900_i2c *i2c = dev_id;
unsigned long status;
status = readl(i2c->regs + CSR);
writel(status | IRQFLAG, i2c->regs + CSR);
if (status & ARBIT_LOST) {
/* deal with arbitration loss */
dev_err(i2c->dev, "deal with arbitration loss\n");
goto out;
}
if (i2c->state == STATE_IDLE) {
dev_dbg(i2c->dev, "IRQ: error i2c->state == IDLE\n");
goto out;
}
/* pretty much this leaves us with the fact that we've
* transmitted or received whatever byte we last sent
*/
i2c_nuc900_irq_nextbyte(i2c, status);
out:
return IRQ_HANDLED;
}
/* nuc900_i2c_set_master
*
* get the i2c bus for a master transaction
*/
static int nuc900_i2c_set_master(struct nuc900_i2c *i2c)
{
int timeout = 400;
while (timeout-- > 0) {
if (((readl(i2c->regs + SWR) & I2CSTART) == I2CSTART) &&
((readl(i2c->regs + CSR) & I2CBUSY) == 0)) {
return 0;
}
msleep(1);
}
return -ETIMEDOUT;
}
/* nuc900_i2c_doxfer
*
* this starts an i2c transfer
*/
static int nuc900_i2c_doxfer(struct nuc900_i2c *i2c,
struct i2c_msg *msgs, int num)
{
unsigned long iicstat, timeout;
int spins = 20;
int ret;
ret = nuc900_i2c_set_master(i2c);
if (ret != 0) {
dev_err(i2c->dev, "cannot get bus (error %d)\n", ret);
ret = -EAGAIN;
goto out;
}
spin_lock_irq(&i2c->lock);
i2c->msg = msgs;
i2c->msg_num = num;
i2c->msg_ptr = 0;
i2c->msg_idx = 0;
i2c->state = STATE_START;
nuc900_i2c_message_start(i2c, msgs);
spin_unlock_irq(&i2c->lock);
timeout = wait_event_timeout(i2c->wait, i2c->msg_num == 0, HZ * 5);
ret = i2c->msg_idx;
/* having these next two as dev_err() makes life very
* noisy when doing an i2cdetect
*/
if (timeout == 0)
dev_dbg(i2c->dev, "timeout\n");
else if (ret != num)
dev_dbg(i2c->dev, "incomplete xfer (%d)\n", ret);
/* ensure the stop has been through the bus */
dev_dbg(i2c->dev, "waiting for bus idle\n");
/* first, try busy waiting briefly */
do {
iicstat = readl(i2c->regs + CSR);
} while ((iicstat & I2CBUSY) && --spins);
/* if that timed out sleep */
if (!spins) {
msleep(1);
iicstat = readl(i2c->regs + CSR);
}
if (iicstat & I2CBUSY)
dev_warn(i2c->dev, "timeout waiting for bus idle\n");
out:
return ret;
}
/* nuc900_i2c_xfer
*
* first port of call from the i2c bus code when an message needs
* transferring across the i2c bus.
*/
static int nuc900_i2c_xfer(struct i2c_adapter *adap,
struct i2c_msg *msgs, int num)
{
struct nuc900_i2c *i2c = (struct nuc900_i2c *)adap->algo_data;
int retry;
int ret;
nuc900_i2c_enable_irq(i2c);
for (retry = 0; retry < adap->retries; retry++) {
ret = nuc900_i2c_doxfer(i2c, msgs, num);
if (ret != -EAGAIN)
return ret;
dev_dbg(i2c->dev, "Retrying transmission (%d)\n", retry);
udelay(100);
}
return -EREMOTEIO;
}
/* declare our i2c functionality */
static u32 nuc900_i2c_func(struct i2c_adapter *adap)
{
return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL | I2C_FUNC_NOSTART |
I2C_FUNC_PROTOCOL_MANGLING;
}
/* i2c bus registration info */
static const struct i2c_algorithm nuc900_i2c_algorithm = {
.master_xfer = nuc900_i2c_xfer,
.functionality = nuc900_i2c_func,
};
/* nuc900_i2c_probe
*
* called by the bus driver when a suitable device is found
*/
static int nuc900_i2c_probe(struct platform_device *pdev)
{
struct nuc900_i2c *i2c;
struct nuc900_platform_i2c *pdata;
struct resource *res;
int ret;
pdata = pdev->dev.platform_data;
if (!pdata) {
dev_err(&pdev->dev, "no platform data\n");
return -EINVAL;
}
i2c = kzalloc(sizeof(struct nuc900_i2c), GFP_KERNEL);
if (!i2c) {
dev_err(&pdev->dev, "no memory for state\n");
return -ENOMEM;
}
strlcpy(i2c->adap.name, "nuc900-i2c0", sizeof(i2c->adap.name));
i2c->adap.owner = THIS_MODULE;
i2c->adap.algo = &nuc900_i2c_algorithm;
i2c->adap.retries = 2;
i2c->adap.class = I2C_CLASS_HWMON | I2C_CLASS_SPD;
spin_lock_init(&i2c->lock);
init_waitqueue_head(&i2c->wait);
/* find the clock and enable it */
i2c->dev = &pdev->dev;
i2c->clk = clk_get(&pdev->dev, NULL);
if (IS_ERR(i2c->clk)) {
dev_err(&pdev->dev, "cannot get clock\n");
ret = -ENOENT;
goto err_noclk;
}
dev_dbg(&pdev->dev, "clock source %p\n", i2c->clk);
clk_enable(i2c->clk);
/* map the registers */
res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
if (res == NULL) {
dev_err(&pdev->dev, "cannot find IO resource\n");
ret = -ENOENT;
goto err_clk;
}
i2c->ioarea = request_mem_region(res->start, resource_size(res),
pdev->name);
if (i2c->ioarea == NULL) {
dev_err(&pdev->dev, "cannot request IO\n");
ret = -ENXIO;
goto err_clk;
}
i2c->regs = ioremap(res->start, resource_size(res));
if (i2c->regs == NULL) {
dev_err(&pdev->dev, "cannot map IO\n");
ret = -ENXIO;
goto err_ioarea;
}
dev_dbg(&pdev->dev, "registers %p (%p, %p)\n",
i2c->regs, i2c->ioarea, res);
/* setup info block for the i2c core */
i2c->adap.algo_data = i2c;
i2c->adap.dev.parent = &pdev->dev;
mfp_set_groupg(&pdev->dev, NULL);
clk_get_rate(i2c->clk);
ret = (i2c->clk.apbfreq)/(pdata->bus_freq * 5) - 1;
writel(ret & 0xffff, i2c->regs + DIVIDER);
/* find the IRQ for this unit (note, this relies on the init call to
* ensure no current IRQs pending
*/
i2c->irq = ret = platform_get_irq(pdev, 0);
if (ret <= 0) {
dev_err(&pdev->dev, "cannot find IRQ\n");
goto err_iomap;
}
ret = request_irq(i2c->irq, nuc900_i2c_irq, IRQF_SHARED,
dev_name(&pdev->dev), i2c);
if (ret != 0) {
dev_err(&pdev->dev, "cannot claim IRQ %d\n", i2c->irq);
goto err_iomap;
}
/* Note, previous versions of the driver used i2c_add_adapter()
* to add the bus at any number. We now pass the bus number via
* the platform data, so if unset it will now default to always
* being bus 0.
*/
i2c->adap.nr = pdata->bus_num;
ret = i2c_add_numbered_adapter(&i2c->adap);
if (ret < 0) {
dev_err(&pdev->dev, "failed to add bus to i2c core\n");
goto err_irq;
}
platform_set_drvdata(pdev, i2c);
dev_info(&pdev->dev, "%s: NUC900 I2C adapter\n",
dev_name(&i2c->adap.dev));
return 0;
err_irq:
free_irq(i2c->irq, i2c);
err_iomap:
iounmap(i2c->regs);
err_ioarea:
release_resource(i2c->ioarea);
kfree(i2c->ioarea);
err_clk:
clk_disable(i2c->clk);
clk_put(i2c->clk);
err_noclk:
kfree(i2c);
return ret;
}
/* nuc900_i2c_remove
*
* called when device is removed from the bus
*/
static int nuc900_i2c_remove(struct platform_device *pdev)
{
struct nuc900_i2c *i2c = platform_get_drvdata(pdev);
i2c_del_adapter(&i2c->adap);
free_irq(i2c->irq, i2c);
clk_disable(i2c->clk);
clk_put(i2c->clk);
iounmap(i2c->regs);
release_resource(i2c->ioarea);
kfree(i2c->ioarea);
kfree(i2c);
return 0;
}
static struct platform_driver nuc900_i2c_driver = {
.probe = nuc900_i2c_probe,
.remove = nuc900_i2c_remove,
.driver = {
.owner = THIS_MODULE,
.name = "nuc900-i2c0",
},
};
static int __init i2c_adap_nuc900_init(void)
{
return platform_driver_register(&nuc900_i2c_driver);
}
static void __exit i2c_adap_nuc900_exit(void)
{
platform_driver_unregister(&nuc900_i2c_driver);
}
subsys_initcall(i2c_adap_nuc900_init);
module_exit(i2c_adap_nuc900_exit);
MODULE_DESCRIPTION("NUC900 I2C Bus driver");
MODULE_AUTHOR("Wan ZongShun, <mcuos.com-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>");
MODULE_LICENSE("GPL");
MODULE_ALIAS("platform:nuc900-i2c0");