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linux/drivers/i2c/busses/i2c-s3c2410.c
Mark Brown 1bc2962e53 i2c-s3c2410: Remove unconditional 1ms delay on each transfer 
The S3C I2C controller indicates completion of I2C transfers before
the bus has a stop condition on it. In order to ensure that we do not
attempt to start a new transfer before the bus is idle the driver
currently inserts a 1ms delay. This is vastly larger than is generally
required and has a visible effect on performance under load, such as
when bringing up audio CODECs or reading back status information with
non-bulk I2C reads.

Replace the sleep with a spin on the IIC status register for up to 1ms.
This will busy wait but testing on my SMDK6410 system indicates that
the overwhelming majority of transactions complete on the first spin,
with maximum latencies of less than 10 spins so the absolute overhead
of busy waiting should be at worst comprable to msleep(), and the
overall system performance is dramatically improved.

The main risk is poor interaction with multimaster systems where
we may miss the bus going idle before the next transaction. Defend
against this by falling back to the original 1ms delay after 20 spins.

The overall effect in my testing is an approximately 20% improvement
in kernel startup time.

Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
Signed-off-by: Ben Dooks <ben-linux@fluff.org>
2010-05-20 00:18:58 +01:00

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/* linux/drivers/i2c/busses/i2c-s3c2410.c
*
* Copyright (C) 2004,2005,2009 Simtec Electronics
* Ben Dooks <ben@simtec.co.uk>
*
* S3C2410 I2C Controller
*
* 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; either version 2 of the License, or
* (at your option) any later version.
*
* 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.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/i2c.h>
#include <linux/i2c-id.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 <asm/irq.h>
#include <asm/io.h>
#include <plat/regs-iic.h>
#include <plat/iic.h>
/* i2c controller state */
enum s3c24xx_i2c_state {
STATE_IDLE,
STATE_START,
STATE_READ,
STATE_WRITE,
STATE_STOP
};
enum s3c24xx_i2c_type {
TYPE_S3C2410,
TYPE_S3C2440,
};
struct s3c24xx_i2c {
spinlock_t lock;
wait_queue_head_t wait;
unsigned int suspended:1;
struct i2c_msg *msg;
unsigned int msg_num;
unsigned int msg_idx;
unsigned int msg_ptr;
unsigned int tx_setup;
unsigned int irq;
enum s3c24xx_i2c_state state;
unsigned long clkrate;
void __iomem *regs;
struct clk *clk;
struct device *dev;
struct resource *ioarea;
struct i2c_adapter adap;
#ifdef CONFIG_CPU_FREQ
struct notifier_block freq_transition;
#endif
};
/* default platform data removed, dev should always carry data. */
/* s3c24xx_i2c_is2440()
*
* return true is this is an s3c2440
*/
static inline int s3c24xx_i2c_is2440(struct s3c24xx_i2c *i2c)
{
struct platform_device *pdev = to_platform_device(i2c->dev);
enum s3c24xx_i2c_type type;
type = platform_get_device_id(pdev)->driver_data;
return type == TYPE_S3C2440;
}
/* s3c24xx_i2c_master_complete
*
* complete the message and wake up the caller, using the given return code,
* or zero to mean ok.
*/
static inline void s3c24xx_i2c_master_complete(struct s3c24xx_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);
}
static inline void s3c24xx_i2c_disable_ack(struct s3c24xx_i2c *i2c)
{
unsigned long tmp;
tmp = readl(i2c->regs + S3C2410_IICCON);
writel(tmp & ~S3C2410_IICCON_ACKEN, i2c->regs + S3C2410_IICCON);
}
static inline void s3c24xx_i2c_enable_ack(struct s3c24xx_i2c *i2c)
{
unsigned long tmp;
tmp = readl(i2c->regs + S3C2410_IICCON);
writel(tmp | S3C2410_IICCON_ACKEN, i2c->regs + S3C2410_IICCON);
}
/* irq enable/disable functions */
static inline void s3c24xx_i2c_disable_irq(struct s3c24xx_i2c *i2c)
{
unsigned long tmp;
tmp = readl(i2c->regs + S3C2410_IICCON);
writel(tmp & ~S3C2410_IICCON_IRQEN, i2c->regs + S3C2410_IICCON);
}
static inline void s3c24xx_i2c_enable_irq(struct s3c24xx_i2c *i2c)
{
unsigned long tmp;
tmp = readl(i2c->regs + S3C2410_IICCON);
writel(tmp | S3C2410_IICCON_IRQEN, i2c->regs + S3C2410_IICCON);
}
/* s3c24xx_i2c_message_start
*
* put the start of a message onto the bus
*/
static void s3c24xx_i2c_message_start(struct s3c24xx_i2c *i2c,
struct i2c_msg *msg)
{
unsigned int addr = (msg->addr & 0x7f) << 1;
unsigned long stat;
unsigned long iiccon;
stat = 0;
stat |= S3C2410_IICSTAT_TXRXEN;
if (msg->flags & I2C_M_RD) {
stat |= S3C2410_IICSTAT_MASTER_RX;
addr |= 1;
} else
stat |= S3C2410_IICSTAT_MASTER_TX;
if (msg->flags & I2C_M_REV_DIR_ADDR)
addr ^= 1;
/* todo - check for wether ack wanted or not */
s3c24xx_i2c_enable_ack(i2c);
iiccon = readl(i2c->regs + S3C2410_IICCON);
writel(stat, i2c->regs + S3C2410_IICSTAT);
dev_dbg(i2c->dev, "START: %08lx to IICSTAT, %02x to DS\n", stat, addr);
writeb(addr, i2c->regs + S3C2410_IICDS);
/* delay here to ensure the data byte has gotten onto the bus
* before the transaction is started */
ndelay(i2c->tx_setup);
dev_dbg(i2c->dev, "iiccon, %08lx\n", iiccon);
writel(iiccon, i2c->regs + S3C2410_IICCON);
stat |= S3C2410_IICSTAT_START;
writel(stat, i2c->regs + S3C2410_IICSTAT);
}
static inline void s3c24xx_i2c_stop(struct s3c24xx_i2c *i2c, int ret)
{
unsigned long iicstat = readl(i2c->regs + S3C2410_IICSTAT);
dev_dbg(i2c->dev, "STOP\n");
/* stop the transfer */
iicstat &= ~S3C2410_IICSTAT_START;
writel(iicstat, i2c->regs + S3C2410_IICSTAT);
i2c->state = STATE_STOP;
s3c24xx_i2c_master_complete(i2c, ret);
s3c24xx_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 s3c24xx_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 s3c24xx_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 s3c24xx_i2c *i2c)
{
return i2c->msg_ptr >= i2c->msg->len;
}
/* i2s_s3c_irq_nextbyte
*
* process an interrupt and work out what to do
*/
static int i2s_s3c_irq_nextbyte(struct s3c24xx_i2c *i2c, unsigned long iicstat)
{
unsigned long tmp;
unsigned char byte;
int ret = 0;
switch (i2c->state) {
case STATE_IDLE:
dev_err(i2c->dev, "%s: called in STATE_IDLE\n", __func__);
goto out;
break;
case STATE_STOP:
dev_err(i2c->dev, "%s: called in STATE_STOP\n", __func__);
s3c24xx_i2c_disable_irq(i2c);
goto out_ack;
case STATE_START:
/* last thing we did was send a start condition on the
* bus, or started a new i2c message
*/
if (iicstat & S3C2410_IICSTAT_LASTBIT &&
!(i2c->msg->flags & I2C_M_IGNORE_NAK)) {
/* ack was not received... */
dev_dbg(i2c->dev, "ack was not received\n");
s3c24xx_i2c_stop(i2c, -ENXIO);
goto out_ack;
}
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) {
s3c24xx_i2c_stop(i2c, 0);
goto out_ack;
}
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 & S3C2410_IICSTAT_LASTBIT) {
dev_dbg(i2c->dev, "WRITE: No Ack\n");
s3c24xx_i2c_stop(i2c, -ECONNREFUSED);
goto out_ack;
}
}
retry_write:
if (!is_msgend(i2c)) {
byte = i2c->msg->buf[i2c->msg_ptr++];
writeb(byte, i2c->regs + S3C2410_IICDS);
/* delay after writing the byte to allow the
* data setup time on the bus, as writing the
* data to the register causes the first bit
* to appear on SDA, and SCL will change as
* soon as the interrupt is acknowledged */
ndelay(i2c->tx_setup);
} 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 */
s3c24xx_i2c_stop(i2c, -EINVAL);
}
goto retry_write;
} else {
/* send the new start */
s3c24xx_i2c_message_start(i2c, i2c->msg);
i2c->state = STATE_START;
}
} else {
/* send stop */
s3c24xx_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 wether we are
* going to do any more read/write
*/
byte = readb(i2c->regs + S3C2410_IICDS);
i2c->msg->buf[i2c->msg_ptr++] = byte;
prepare_read:
if (is_msglast(i2c)) {
/* last byte of buffer */
if (is_lastmsg(i2c))
s3c24xx_i2c_disable_ack(i2c);
} 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");
s3c24xx_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++;
}
}
break;
}
/* acknowlegde the IRQ and get back on with the work */
out_ack:
tmp = readl(i2c->regs + S3C2410_IICCON);
tmp &= ~S3C2410_IICCON_IRQPEND;
writel(tmp, i2c->regs + S3C2410_IICCON);
out:
return ret;
}
/* s3c24xx_i2c_irq
*
* top level IRQ servicing routine
*/
static irqreturn_t s3c24xx_i2c_irq(int irqno, void *dev_id)
{
struct s3c24xx_i2c *i2c = dev_id;
unsigned long status;
unsigned long tmp;
status = readl(i2c->regs + S3C2410_IICSTAT);
if (status & S3C2410_IICSTAT_ARBITR) {
/* deal with arbitration loss */
dev_err(i2c->dev, "deal with arbitration loss\n");
}
if (i2c->state == STATE_IDLE) {
dev_dbg(i2c->dev, "IRQ: error i2c->state == IDLE\n");
tmp = readl(i2c->regs + S3C2410_IICCON);
tmp &= ~S3C2410_IICCON_IRQPEND;
writel(tmp, i2c->regs + S3C2410_IICCON);
goto out;
}
/* pretty much this leaves us with the fact that we've
* transmitted or received whatever byte we last sent */
i2s_s3c_irq_nextbyte(i2c, status);
out:
return IRQ_HANDLED;
}
/* s3c24xx_i2c_set_master
*
* get the i2c bus for a master transaction
*/
static int s3c24xx_i2c_set_master(struct s3c24xx_i2c *i2c)
{
unsigned long iicstat;
int timeout = 400;
while (timeout-- > 0) {
iicstat = readl(i2c->regs + S3C2410_IICSTAT);
if (!(iicstat & S3C2410_IICSTAT_BUSBUSY))
return 0;
msleep(1);
}
return -ETIMEDOUT;
}
/* s3c24xx_i2c_doxfer
*
* this starts an i2c transfer
*/
static int s3c24xx_i2c_doxfer(struct s3c24xx_i2c *i2c,
struct i2c_msg *msgs, int num)
{
unsigned long iicstat, timeout;
int spins = 20;
int ret;
if (i2c->suspended)
return -EIO;
ret = s3c24xx_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;
s3c24xx_i2c_enable_irq(i2c);
s3c24xx_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 + S3C2410_IICSTAT);
} while ((iicstat & S3C2410_IICSTAT_START) && --spins);
/* if that timed out sleep */
if (!spins) {
msleep(1);
iicstat = readl(i2c->regs + S3C2410_IICSTAT);
}
if (iicstat & S3C2410_IICSTAT_START)
dev_warn(i2c->dev, "timeout waiting for bus idle\n");
out:
return ret;
}
/* s3c24xx_i2c_xfer
*
* first port of call from the i2c bus code when an message needs
* transferring across the i2c bus.
*/
static int s3c24xx_i2c_xfer(struct i2c_adapter *adap,
struct i2c_msg *msgs, int num)
{
struct s3c24xx_i2c *i2c = (struct s3c24xx_i2c *)adap->algo_data;
int retry;
int ret;
for (retry = 0; retry < adap->retries; retry++) {
ret = s3c24xx_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 s3c24xx_i2c_func(struct i2c_adapter *adap)
{
return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL | I2C_FUNC_PROTOCOL_MANGLING;
}
/* i2c bus registration info */
static const struct i2c_algorithm s3c24xx_i2c_algorithm = {
.master_xfer = s3c24xx_i2c_xfer,
.functionality = s3c24xx_i2c_func,
};
/* s3c24xx_i2c_calcdivisor
*
* return the divisor settings for a given frequency
*/
static int s3c24xx_i2c_calcdivisor(unsigned long clkin, unsigned int wanted,
unsigned int *div1, unsigned int *divs)
{
unsigned int calc_divs = clkin / wanted;
unsigned int calc_div1;
if (calc_divs > (16*16))
calc_div1 = 512;
else
calc_div1 = 16;
calc_divs += calc_div1-1;
calc_divs /= calc_div1;
if (calc_divs == 0)
calc_divs = 1;
if (calc_divs > 17)
calc_divs = 17;
*divs = calc_divs;
*div1 = calc_div1;
return clkin / (calc_divs * calc_div1);
}
/* s3c24xx_i2c_clockrate
*
* work out a divisor for the user requested frequency setting,
* either by the requested frequency, or scanning the acceptable
* range of frequencies until something is found
*/
static int s3c24xx_i2c_clockrate(struct s3c24xx_i2c *i2c, unsigned int *got)
{
struct s3c2410_platform_i2c *pdata = i2c->dev->platform_data;
unsigned long clkin = clk_get_rate(i2c->clk);
unsigned int divs, div1;
unsigned long target_frequency;
u32 iiccon;
int freq;
i2c->clkrate = clkin;
clkin /= 1000; /* clkin now in KHz */
dev_dbg(i2c->dev, "pdata desired frequency %lu\n", pdata->frequency);
target_frequency = pdata->frequency ? pdata->frequency : 100000;
target_frequency /= 1000; /* Target frequency now in KHz */
freq = s3c24xx_i2c_calcdivisor(clkin, target_frequency, &div1, &divs);
if (freq > target_frequency) {
dev_err(i2c->dev,
"Unable to achieve desired frequency %luKHz." \
" Lowest achievable %dKHz\n", target_frequency, freq);
return -EINVAL;
}
*got = freq;
iiccon = readl(i2c->regs + S3C2410_IICCON);
iiccon &= ~(S3C2410_IICCON_SCALEMASK | S3C2410_IICCON_TXDIV_512);
iiccon |= (divs-1);
if (div1 == 512)
iiccon |= S3C2410_IICCON_TXDIV_512;
writel(iiccon, i2c->regs + S3C2410_IICCON);
if (s3c24xx_i2c_is2440(i2c)) {
unsigned long sda_delay;
if (pdata->sda_delay) {
sda_delay = (freq / 1000) * pdata->sda_delay;
sda_delay /= 1000000;
sda_delay = DIV_ROUND_UP(sda_delay, 5);
if (sda_delay > 3)
sda_delay = 3;
sda_delay |= S3C2410_IICLC_FILTER_ON;
} else
sda_delay = 0;
dev_dbg(i2c->dev, "IICLC=%08lx\n", sda_delay);
writel(sda_delay, i2c->regs + S3C2440_IICLC);
}
return 0;
}
#ifdef CONFIG_CPU_FREQ
#define freq_to_i2c(_n) container_of(_n, struct s3c24xx_i2c, freq_transition)
static int s3c24xx_i2c_cpufreq_transition(struct notifier_block *nb,
unsigned long val, void *data)
{
struct s3c24xx_i2c *i2c = freq_to_i2c(nb);
unsigned long flags;
unsigned int got;
int delta_f;
int ret;
delta_f = clk_get_rate(i2c->clk) - i2c->clkrate;
/* if we're post-change and the input clock has slowed down
* or at pre-change and the clock is about to speed up, then
* adjust our clock rate. <0 is slow, >0 speedup.
*/
if ((val == CPUFREQ_POSTCHANGE && delta_f < 0) ||
(val == CPUFREQ_PRECHANGE && delta_f > 0)) {
spin_lock_irqsave(&i2c->lock, flags);
ret = s3c24xx_i2c_clockrate(i2c, &got);
spin_unlock_irqrestore(&i2c->lock, flags);
if (ret < 0)
dev_err(i2c->dev, "cannot find frequency\n");
else
dev_info(i2c->dev, "setting freq %d\n", got);
}
return 0;
}
static inline int s3c24xx_i2c_register_cpufreq(struct s3c24xx_i2c *i2c)
{
i2c->freq_transition.notifier_call = s3c24xx_i2c_cpufreq_transition;
return cpufreq_register_notifier(&i2c->freq_transition,
CPUFREQ_TRANSITION_NOTIFIER);
}
static inline void s3c24xx_i2c_deregister_cpufreq(struct s3c24xx_i2c *i2c)
{
cpufreq_unregister_notifier(&i2c->freq_transition,
CPUFREQ_TRANSITION_NOTIFIER);
}
#else
static inline int s3c24xx_i2c_register_cpufreq(struct s3c24xx_i2c *i2c)
{
return 0;
}
static inline void s3c24xx_i2c_deregister_cpufreq(struct s3c24xx_i2c *i2c)
{
}
#endif
/* s3c24xx_i2c_init
*
* initialise the controller, set the IO lines and frequency
*/
static int s3c24xx_i2c_init(struct s3c24xx_i2c *i2c)
{
unsigned long iicon = S3C2410_IICCON_IRQEN | S3C2410_IICCON_ACKEN;
struct s3c2410_platform_i2c *pdata;
unsigned int freq;
/* get the plafrom data */
pdata = i2c->dev->platform_data;
/* inititalise the gpio */
if (pdata->cfg_gpio)
pdata->cfg_gpio(to_platform_device(i2c->dev));
/* write slave address */
writeb(pdata->slave_addr, i2c->regs + S3C2410_IICADD);
dev_info(i2c->dev, "slave address 0x%02x\n", pdata->slave_addr);
writel(iicon, i2c->regs + S3C2410_IICCON);
/* we need to work out the divisors for the clock... */
if (s3c24xx_i2c_clockrate(i2c, &freq) != 0) {
writel(0, i2c->regs + S3C2410_IICCON);
dev_err(i2c->dev, "cannot meet bus frequency required\n");
return -EINVAL;
}
/* todo - check that the i2c lines aren't being dragged anywhere */
dev_info(i2c->dev, "bus frequency set to %d KHz\n", freq);
dev_dbg(i2c->dev, "S3C2410_IICCON=0x%02lx\n", iicon);
return 0;
}
/* s3c24xx_i2c_probe
*
* called by the bus driver when a suitable device is found
*/
static int s3c24xx_i2c_probe(struct platform_device *pdev)
{
struct s3c24xx_i2c *i2c;
struct s3c2410_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 s3c24xx_i2c), GFP_KERNEL);
if (!i2c) {
dev_err(&pdev->dev, "no memory for state\n");
return -ENOMEM;
}
strlcpy(i2c->adap.name, "s3c2410-i2c", sizeof(i2c->adap.name));
i2c->adap.owner = THIS_MODULE;
i2c->adap.algo = &s3c24xx_i2c_algorithm;
i2c->adap.retries = 2;
i2c->adap.class = I2C_CLASS_HWMON | I2C_CLASS_SPD;
i2c->tx_setup = 50;
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, "i2c");
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;
/* initialise the i2c controller */
ret = s3c24xx_i2c_init(i2c);
if (ret != 0)
goto err_iomap;
/* 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, s3c24xx_i2c_irq, IRQF_DISABLED,
dev_name(&pdev->dev), i2c);
if (ret != 0) {
dev_err(&pdev->dev, "cannot claim IRQ %d\n", i2c->irq);
goto err_iomap;
}
ret = s3c24xx_i2c_register_cpufreq(i2c);
if (ret < 0) {
dev_err(&pdev->dev, "failed to register cpufreq notifier\n");
goto err_irq;
}
/* 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_cpufreq;
}
platform_set_drvdata(pdev, i2c);
dev_info(&pdev->dev, "%s: S3C I2C adapter\n", dev_name(&i2c->adap.dev));
return 0;
err_cpufreq:
s3c24xx_i2c_deregister_cpufreq(i2c);
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;
}
/* s3c24xx_i2c_remove
*
* called when device is removed from the bus
*/
static int s3c24xx_i2c_remove(struct platform_device *pdev)
{
struct s3c24xx_i2c *i2c = platform_get_drvdata(pdev);
s3c24xx_i2c_deregister_cpufreq(i2c);
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;
}
#ifdef CONFIG_PM
static int s3c24xx_i2c_suspend_noirq(struct device *dev)
{
struct platform_device *pdev = to_platform_device(dev);
struct s3c24xx_i2c *i2c = platform_get_drvdata(pdev);
i2c->suspended = 1;
return 0;
}
static int s3c24xx_i2c_resume(struct device *dev)
{
struct platform_device *pdev = to_platform_device(dev);
struct s3c24xx_i2c *i2c = platform_get_drvdata(pdev);
i2c->suspended = 0;
s3c24xx_i2c_init(i2c);
return 0;
}
static const struct dev_pm_ops s3c24xx_i2c_dev_pm_ops = {
.suspend_noirq = s3c24xx_i2c_suspend_noirq,
.resume = s3c24xx_i2c_resume,
};
#define S3C24XX_DEV_PM_OPS (&s3c24xx_i2c_dev_pm_ops)
#else
#define S3C24XX_DEV_PM_OPS NULL
#endif
/* device driver for platform bus bits */
static struct platform_device_id s3c24xx_driver_ids[] = {
{
.name = "s3c2410-i2c",
.driver_data = TYPE_S3C2410,
}, {
.name = "s3c2440-i2c",
.driver_data = TYPE_S3C2440,
}, { },
};
MODULE_DEVICE_TABLE(platform, s3c24xx_driver_ids);
static struct platform_driver s3c24xx_i2c_driver = {
.probe = s3c24xx_i2c_probe,
.remove = s3c24xx_i2c_remove,
.id_table = s3c24xx_driver_ids,
.driver = {
.owner = THIS_MODULE,
.name = "s3c-i2c",
.pm = S3C24XX_DEV_PM_OPS,
},
};
static int __init i2c_adap_s3c_init(void)
{
return platform_driver_register(&s3c24xx_i2c_driver);
}
subsys_initcall(i2c_adap_s3c_init);
static void __exit i2c_adap_s3c_exit(void)
{
platform_driver_unregister(&s3c24xx_i2c_driver);
}
module_exit(i2c_adap_s3c_exit);
MODULE_DESCRIPTION("S3C24XX I2C Bus driver");
MODULE_AUTHOR("Ben Dooks, <ben@simtec.co.uk>");
MODULE_LICENSE("GPL");
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