i2c: S3C24XX I2C frequency scaling support.
Add support for CPU frequency scaling to the S3C24XX I2C driver.
Signed-off-by: Ben Dooks <ben-linux@fluff.org>
diff --git a/drivers/i2c/busses/i2c-s3c2410.c b/drivers/i2c/busses/i2c-s3c2410.c
index eef35d3..4864723 100644
--- a/drivers/i2c/busses/i2c-s3c2410.c
+++ b/drivers/i2c/busses/i2c-s3c2410.c
@@ -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 @@
unsigned int tx_setup;
enum s3c24xx_i2c_state state;
+ unsigned long clkrate;
void __iomem *regs;
struct clk *clk;
@@ -71,6 +73,10 @@
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 @@
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);
@@ -636,27 +645,28 @@
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",
+ dev_dbg(i2c->dev, "pdata %p, freq %lu %lu..%lu\n",
pdata, pdata->bus_freq, pdata->min_freq, pdata->max_freq);
if (pdata->bus_freq != 0) {
@@ -688,11 +698,79 @@
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 @@
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;
}
@@ -730,8 +811,6 @@
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 */
@@ -835,6 +914,12 @@
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 @@
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 @@
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 @@
{
struct s3c24xx_i2c *i2c = platform_get_drvdata(pdev);
+ s3c24xx_i2c_deregister_cpufreq(i2c);
+
i2c_del_adapter(&i2c->adap);
free_irq(i2c->irq->start, i2c);