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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>
This commit is contained in:
Ben Dooks
parent
1efe7c55d2
commit
61c7cff892
1 changed files with 103 additions and 13 deletions
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@ -33,6 +33,7 @@
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#include <linux/err.h>
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#include <linux/platform_device.h>
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#include <linux/clk.h>
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#include <linux/cpufreq.h>
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#include <asm/hardware.h>
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#include <asm/irq.h>
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@ -64,6 +65,7 @@ struct s3c24xx_i2c {
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unsigned int tx_setup;
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enum s3c24xx_i2c_state state;
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unsigned long clkrate;
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void __iomem *regs;
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struct clk *clk;
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@ -71,6 +73,10 @@ struct s3c24xx_i2c {
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struct resource *irq;
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struct resource *ioarea;
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struct i2c_adapter adap;
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#ifdef CONFIG_CPU_FREQ
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struct notifier_block freq_transition;
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#endif
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};
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/* default platform data to use if not supplied in the platform_device
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@ -501,6 +507,9 @@ static int s3c24xx_i2c_doxfer(struct s3c24xx_i2c *i2c, struct i2c_msg *msgs, int
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unsigned long timeout;
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int ret;
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if (!readl(i2c->regs + S3C2410_IICCON) & S3C2410_IICCON_IRQEN)
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return -EIO;
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ret = s3c24xx_i2c_set_master(i2c);
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if (ret != 0) {
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dev_err(i2c->dev, "cannot get bus (error %d)\n", ret);
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@ -636,27 +645,28 @@ static inline int freq_acceptable(unsigned int freq, unsigned int wanted)
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return (diff >= -2 && diff <= 2);
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}
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/* s3c24xx_i2c_getdivisor
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/* s3c24xx_i2c_clockrate
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*
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* work out a divisor for the user requested frequency setting,
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* either by the requested frequency, or scanning the acceptable
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* range of frequencies until something is found
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*/
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static int s3c24xx_i2c_getdivisor(struct s3c24xx_i2c *i2c,
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struct s3c2410_platform_i2c *pdata,
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unsigned long *iicon,
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unsigned int *got)
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static int s3c24xx_i2c_clockrate(struct s3c24xx_i2c *i2c, unsigned int *got)
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{
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struct s3c2410_platform_i2c *pdata;
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unsigned long clkin = clk_get_rate(i2c->clk);
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unsigned int divs, div1;
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u32 iiccon;
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int freq;
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int start, end;
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i2c->clkrate = clkin;
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pdata = s3c24xx_i2c_get_platformdata(i2c->adap.dev.parent);
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clkin /= 1000; /* clkin now in KHz */
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dev_dbg(i2c->dev, "pdata %p, freq %lu %lu..%lu\n",
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dev_dbg(i2c->dev, "pdata %p, freq %lu %lu..%lu\n",
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pdata, pdata->bus_freq, pdata->min_freq, pdata->max_freq);
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if (pdata->bus_freq != 0) {
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@ -688,11 +698,79 @@ static int s3c24xx_i2c_getdivisor(struct s3c24xx_i2c *i2c,
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found:
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*got = freq;
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*iicon |= (divs-1);
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*iicon |= (div1 == 512) ? S3C2410_IICCON_TXDIV_512 : 0;
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iiccon = readl(i2c->regs + S3C2410_IICCON);
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iiccon &= ~(S3C2410_IICCON_SCALEMASK | S3C2410_IICCON_TXDIV_512);
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iiccon |= (divs-1);
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if (div1 == 512)
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iiccon |= S3C2410_IICCON_TXDIV_512;
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writel(iiccon, i2c->regs + S3C2410_IICCON);
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return 0;
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}
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#ifdef CONFIG_CPU_FREQ
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#define freq_to_i2c(_n) container_of(_n, struct s3c24xx_i2c, freq_transition)
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static int s3c24xx_i2c_cpufreq_transition(struct notifier_block *nb,
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unsigned long val, void *data)
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{
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struct s3c24xx_i2c *i2c = freq_to_i2c(nb);
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unsigned long flags;
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unsigned int got;
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int delta_f;
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int ret;
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delta_f = clk_get_rate(i2c->clk) - i2c->clkrate;
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/* if we're post-change and the input clock has slowed down
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* or at pre-change and the clock is about to speed up, then
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* adjust our clock rate. <0 is slow, >0 speedup.
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*/
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if ((val == CPUFREQ_POSTCHANGE && delta_f < 0) ||
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(val == CPUFREQ_PRECHANGE && delta_f > 0)) {
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spin_lock_irqsave(&i2c->lock, flags);
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ret = s3c24xx_i2c_clockrate(i2c, &got);
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spin_unlock_irqrestore(&i2c->lock, flags);
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if (ret < 0)
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dev_err(i2c->dev, "cannot find frequency\n");
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else
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dev_info(i2c->dev, "setting freq %d\n", got);
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}
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return 0;
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}
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static inline int s3c24xx_i2c_register_cpufreq(struct s3c24xx_i2c *i2c)
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{
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i2c->freq_transition.notifier_call = s3c24xx_i2c_cpufreq_transition;
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return cpufreq_register_notifier(&i2c->freq_transition,
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CPUFREQ_TRANSITION_NOTIFIER);
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}
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static inline void s3c24xx_i2c_deregister_cpufreq(struct s3c24xx_i2c *i2c)
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{
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cpufreq_unregister_notifier(&i2c->freq_transition,
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CPUFREQ_TRANSITION_NOTIFIER);
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}
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#else
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static inline int s3c24xx_i2c_register_cpufreq(struct s3c24xx_i2c *i2c)
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{
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return 0;
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}
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static inline void s3c24xx_i2c_deregister_cpufreq(struct s3c24xx_i2c *i2c)
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{
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}
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#endif
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/* s3c24xx_i2c_init
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*
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* initialise the controller, set the IO lines and frequency
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@ -719,9 +797,12 @@ static int s3c24xx_i2c_init(struct s3c24xx_i2c *i2c)
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dev_info(i2c->dev, "slave address 0x%02x\n", pdata->slave_addr);
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writel(iicon, i2c->regs + S3C2410_IICCON);
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/* we need to work out the divisors for the clock... */
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if (s3c24xx_i2c_getdivisor(i2c, pdata, &iicon, &freq) != 0) {
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if (s3c24xx_i2c_clockrate(i2c, &freq) != 0) {
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writel(0, i2c->regs + S3C2410_IICCON);
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dev_err(i2c->dev, "cannot meet bus frequency required\n");
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return -EINVAL;
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}
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@ -730,8 +811,6 @@ static int s3c24xx_i2c_init(struct s3c24xx_i2c *i2c)
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dev_info(i2c->dev, "bus frequency set to %d KHz\n", freq);
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dev_dbg(i2c->dev, "S3C2410_IICCON=0x%02lx\n", iicon);
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writel(iicon, i2c->regs + S3C2410_IICCON);
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/* check for s3c2440 i2c controller */
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@ -835,6 +914,12 @@ static int s3c24xx_i2c_probe(struct platform_device *pdev)
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dev_dbg(&pdev->dev, "irq resource %p (%lu)\n", res,
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(unsigned long)res->start);
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ret = s3c24xx_i2c_register_cpufreq(i2c);
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if (ret < 0) {
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dev_err(&pdev->dev, "failed to register cpufreq notifier\n");
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goto err_irq;
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}
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/* Note, previous versions of the driver used i2c_add_adapter()
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* to add the bus at any number. We now pass the bus number via
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* the platform data, so if unset it will now default to always
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@ -846,7 +931,7 @@ static int s3c24xx_i2c_probe(struct platform_device *pdev)
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ret = i2c_add_numbered_adapter(&i2c->adap);
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if (ret < 0) {
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dev_err(&pdev->dev, "failed to add bus to i2c core\n");
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goto err_irq;
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goto err_cpufreq;
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}
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platform_set_drvdata(pdev, i2c);
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@ -854,6 +939,9 @@ static int s3c24xx_i2c_probe(struct platform_device *pdev)
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dev_info(&pdev->dev, "%s: S3C I2C adapter\n", i2c->adap.dev.bus_id);
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return 0;
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err_cpufreq:
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s3c24xx_i2c_deregister_cpufreq(i2c);
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err_irq:
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free_irq(i2c->irq->start, i2c);
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@ -881,6 +969,8 @@ static int s3c24xx_i2c_remove(struct platform_device *pdev)
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{
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struct s3c24xx_i2c *i2c = platform_get_drvdata(pdev);
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s3c24xx_i2c_deregister_cpufreq(i2c);
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i2c_del_adapter(&i2c->adap);
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free_irq(i2c->irq->start, i2c);
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