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Commit 61c7cff8 authored by Ben Dooks's avatar Ben Dooks
Browse files

i2c: S3C24XX I2C frequency scaling support. 



Add support for CPU frequency scaling to the S3C24XX I2C driver.

Signed-off-by: default avatarBen Dooks <ben-linux@fluff.org>
parent 1efe7c55

drivers/i2c/busses/i2c-s3c2410.c

+103 −13
Original line number Diff line number Diff line
@@ -33,6 +33,7 @@ 
#include <linux/err.h>

#include <linux/platform_device.h>

#include <linux/clk.h>

#include <linux/cpufreq.h>



#include <asm/hardware.h>

#include <asm/irq.h>
@@ -64,6 +65,7 @@ struct s3c24xx_i2c { 
	unsigned int		tx_setup;



	enum s3c24xx_i2c_state	state;

	unsigned long		clkrate;



	void __iomem		*regs;

	struct clk		*clk;
@@ -71,6 +73,10 @@ struct s3c24xx_i2c { 
	struct resource		*irq;

	struct resource		*ioarea;

	struct i2c_adapter	adap;



#ifdef CONFIG_CPU_FREQ

	struct notifier_block	freq_transition;

#endif

};



/* default platform data to use if not supplied in the platform_device
@@ -501,6 +507,9 @@ static int s3c24xx_i2c_doxfer(struct s3c24xx_i2c *i2c, struct i2c_msg *msgs, int 
	unsigned long timeout;

	int ret;



	if (!readl(i2c->regs + S3C2410_IICCON) & S3C2410_IICCON_IRQEN)

		return -EIO;



	ret = s3c24xx_i2c_set_master(i2c);

	if (ret != 0) {

		dev_err(i2c->dev, "cannot get bus (error %d)\n", ret);
@@ -636,24 +645,25 @@ static inline int freq_acceptable(unsigned int freq, unsigned int wanted) 
	return (diff >= -2 && diff <= 2);

}



/* s3c24xx_i2c_getdivisor

/* 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_getdivisor(struct s3c24xx_i2c *i2c,

				  struct s3c2410_platform_i2c *pdata,

				  unsigned long *iicon,

				  unsigned int *got)

static int s3c24xx_i2c_clockrate(struct s3c24xx_i2c *i2c, unsigned int *got)

{

	struct s3c2410_platform_i2c *pdata;

	unsigned long clkin = clk_get_rate(i2c->clk);

	

	unsigned int divs, div1;

	u32 iiccon;

	int freq;

	int start, end;



	i2c->clkrate = clkin;



	pdata = s3c24xx_i2c_get_platformdata(i2c->adap.dev.parent);

	clkin /= 1000;		/* clkin now in KHz */

     

	dev_dbg(i2c->dev, "pdata %p, freq %lu %lu..%lu\n",
@@ -688,11 +698,79 @@ static int s3c24xx_i2c_getdivisor(struct s3c24xx_i2c *i2c, 


 found:

	*got = freq;

	*iicon |= (divs-1);

	*iicon |= (div1 == 512) ? S3C2410_IICCON_TXDIV_512 : 0;



	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);



	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
@@ -719,9 +797,12 @@ static int s3c24xx_i2c_init(struct s3c24xx_i2c *i2c) 


	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_getdivisor(i2c, pdata, &iicon, &freq) != 0) {

	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;

	}
@@ -731,8 +812,6 @@ static int s3c24xx_i2c_init(struct s3c24xx_i2c *i2c) 
	dev_info(i2c->dev, "bus frequency set to %d KHz\n", freq);

	dev_dbg(i2c->dev, "S3C2410_IICCON=0x%02lx\n", iicon);



	writel(iicon, i2c->regs + S3C2410_IICCON);



	/* check for s3c2440 i2c controller  */



	if (s3c24xx_i2c_is2440(i2c)) {
@@ -835,6 +914,12 @@ static int s3c24xx_i2c_probe(struct platform_device *pdev) 
	dev_dbg(&pdev->dev, "irq resource %p (%lu)\n", res,

		(unsigned long)res->start);



	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
@@ -846,7 +931,7 @@ static int s3c24xx_i2c_probe(struct platform_device *pdev) 
	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;

		goto err_cpufreq;

	}



	platform_set_drvdata(pdev, i2c);
@@ -854,6 +939,9 @@ static int s3c24xx_i2c_probe(struct platform_device *pdev) 
	dev_info(&pdev->dev, "%s: S3C I2C adapter\n", i2c->adap.dev.bus_id);

	return 0;



 err_cpufreq:

	s3c24xx_i2c_deregister_cpufreq(i2c);



 err_irq:

	free_irq(i2c->irq->start, i2c);
@@ -881,6 +969,8 @@ 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->start, i2c);