diff options
author | Linus Torvalds <torvalds@linux-foundation.org> | 2012-12-18 16:51:10 -0800 |
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committer | Linus Torvalds <torvalds@linux-foundation.org> | 2012-12-18 16:51:10 -0800 |
commit | 752451f01c4567b506bf4343082682dbb8fb30dd (patch) | |
tree | ec2ec2989c93e567952ddc1ec879013aa2704f0a /drivers/i2c/busses/i2c-s3c2410.c | |
parent | 673ab8783b596cda5b616b317b1a1b47480c66fd (diff) | |
parent | 972deb4f49b5b6703d9c6117ba0aeda2180d4447 (diff) |
Merge branch 'i2c-embedded/for-next' of git://git.pengutronix.de/git/wsa/linux
Pull i2c-embedded changes from Wolfram Sang:
- CBUS driver (an I2C variant)
- continued rework of the omap driver
- s3c2410 gets lots of fixes and gains pinctrl support
- at91 gains DMA support
- the GPIO muxer gains devicetree probing
- typical fixes and additions all over
* 'i2c-embedded/for-next' of git://git.pengutronix.de/git/wsa/linux: (45 commits)
i2c: omap: Remove the OMAP_I2C_FLAG_RESET_REGS_POSTIDLE flag
i2c: at91: add dma support
i2c: at91: change struct members indentation
i2c: at91: fix compilation warning
i2c: mxs: Do not disable the I2C SMBus quick mode
i2c: mxs: Handle i2c DMA failure properly
i2c: s3c2410: Remove recently introduced performance overheads
i2c: ocores: Move grlib set/get functions into #ifdef CONFIG_OF block
i2c: s3c2410: Add fix for i2c suspend/resume
i2c: s3c2410: Fix code to free gpios
i2c: i2c-cbus-gpio: introduce driver
i2c: ocores: Add support for the GRLIB port of the controller and use function pointers for getreg and setreg functions
i2c: ocores: Add irq support for sparc
i2c: omap: Move the remove constraint
ARM: dts: cfa10049: Add the i2c muxer buses to the CFA-10049
i2c: s3c2410: do not special case HDMIPHY stuck bus detection
i2c: s3c2410: use exponential back off while polling for bus idle
i2c: s3c2410: do not generate STOP for QUIRK_HDMIPHY
i2c: s3c2410: grab adapter lock while changing i2c clock
i2c: s3c2410: Add support for pinctrl
...
Diffstat (limited to 'drivers/i2c/busses/i2c-s3c2410.c')
-rw-r--r-- | drivers/i2c/busses/i2c-s3c2410.c | 211 |
1 files changed, 130 insertions, 81 deletions
diff --git a/drivers/i2c/busses/i2c-s3c2410.c b/drivers/i2c/busses/i2c-s3c2410.c index b33d95ebc89..a290d089cea 100644 --- a/drivers/i2c/busses/i2c-s3c2410.c +++ b/drivers/i2c/busses/i2c-s3c2410.c @@ -38,6 +38,7 @@ #include <linux/io.h> #include <linux/of_i2c.h> #include <linux/of_gpio.h> +#include <linux/pinctrl/consumer.h> #include <asm/irq.h> @@ -49,6 +50,9 @@ #define QUIRK_HDMIPHY (1 << 1) #define QUIRK_NO_GPIO (1 << 2) +/* Max time to wait for bus to become idle after a xfer (in us) */ +#define S3C2410_IDLE_TIMEOUT 5000 + /* i2c controller state */ enum s3c24xx_i2c_state { STATE_IDLE, @@ -59,7 +63,6 @@ enum s3c24xx_i2c_state { }; struct s3c24xx_i2c { - spinlock_t lock; wait_queue_head_t wait; unsigned int quirks; unsigned int suspended:1; @@ -78,11 +81,11 @@ struct s3c24xx_i2c { void __iomem *regs; struct clk *clk; struct device *dev; - struct resource *ioarea; struct i2c_adapter adap; struct s3c2410_platform_i2c *pdata; int gpios[2]; + struct pinctrl *pctrl; #ifdef CONFIG_CPU_FREQ struct notifier_block freq_transition; #endif @@ -235,8 +238,47 @@ static inline void s3c24xx_i2c_stop(struct s3c24xx_i2c *i2c, int ret) dev_dbg(i2c->dev, "STOP\n"); - /* stop the transfer */ - iicstat &= ~S3C2410_IICSTAT_START; + /* + * The datasheet says that the STOP sequence should be: + * 1) I2CSTAT.5 = 0 - Clear BUSY (or 'generate STOP') + * 2) I2CCON.4 = 0 - Clear IRQPEND + * 3) Wait until the stop condition takes effect. + * 4*) I2CSTAT.4 = 0 - Clear TXRXEN + * + * Where, step "4*" is only for buses with the "HDMIPHY" quirk. + * + * However, after much experimentation, it appears that: + * a) normal buses automatically clear BUSY and transition from + * Master->Slave when they complete generating a STOP condition. + * Therefore, step (3) can be done in doxfer() by polling I2CCON.4 + * after starting the STOP generation here. + * b) HDMIPHY bus does neither, so there is no way to do step 3. + * There is no indication when this bus has finished generating + * STOP. + * + * In fact, we have found that as soon as the IRQPEND bit is cleared in + * step 2, the HDMIPHY bus generates the STOP condition, and then + * immediately starts transferring another data byte, even though the + * bus is supposedly stopped. This is presumably because the bus is + * still in "Master" mode, and its BUSY bit is still set. + * + * To avoid these extra post-STOP transactions on HDMI phy devices, we + * just disable Serial Output on the bus (I2CSTAT.4 = 0) directly, + * instead of first generating a proper STOP condition. This should + * float SDA & SCK terminating the transfer. Subsequent transfers + * start with a proper START condition, and proceed normally. + * + * The HDMIPHY bus is an internal bus that always has exactly two + * devices, the host as Master and the HDMIPHY device as the slave. + * Skipping the STOP condition has been tested on this bus and works. + */ + if (i2c->quirks & QUIRK_HDMIPHY) { + /* Stop driving the I2C pins */ + iicstat &= ~S3C2410_IICSTAT_TXRXEN; + } else { + /* stop the transfer */ + iicstat &= ~S3C2410_IICSTAT_START; + } writel(iicstat, i2c->regs + S3C2410_IICSTAT); i2c->state = STATE_STOP; @@ -490,13 +532,6 @@ static int s3c24xx_i2c_set_master(struct s3c24xx_i2c *i2c) unsigned long iicstat; int timeout = 400; - /* the timeout for HDMIPHY is reduced to 10 ms because - * the hangup is expected to happen, so waiting 400 ms - * causes only unnecessary system hangup - */ - if (i2c->quirks & QUIRK_HDMIPHY) - timeout = 10; - while (timeout-- > 0) { iicstat = readl(i2c->regs + S3C2410_IICSTAT); @@ -506,16 +541,61 @@ static int s3c24xx_i2c_set_master(struct s3c24xx_i2c *i2c) msleep(1); } - /* hang-up of bus dedicated for HDMIPHY occurred, resetting */ - if (i2c->quirks & QUIRK_HDMIPHY) { - writel(0, i2c->regs + S3C2410_IICCON); - writel(0, i2c->regs + S3C2410_IICSTAT); - writel(0, i2c->regs + S3C2410_IICDS); + return -ETIMEDOUT; +} - return 0; +/* s3c24xx_i2c_wait_idle + * + * wait for the i2c bus to become idle. +*/ + +static void s3c24xx_i2c_wait_idle(struct s3c24xx_i2c *i2c) +{ + unsigned long iicstat; + ktime_t start, now; + unsigned long delay; + int spins; + + /* ensure the stop has been through the bus */ + + dev_dbg(i2c->dev, "waiting for bus idle\n"); + + start = now = ktime_get(); + + /* + * Most of the time, the bus is already idle within a few usec of the + * end of a transaction. However, really slow i2c devices can stretch + * the clock, delaying STOP generation. + * + * On slower SoCs this typically happens within a very small number of + * instructions so busy wait briefly to avoid scheduling overhead. + */ + spins = 3; + iicstat = readl(i2c->regs + S3C2410_IICSTAT); + while ((iicstat & S3C2410_IICSTAT_START) && --spins) { + cpu_relax(); + iicstat = readl(i2c->regs + S3C2410_IICSTAT); } - return -ETIMEDOUT; + /* + * If we do get an appreciable delay as a compromise between idle + * detection latency for the normal, fast case, and system load in the + * slow device case, use an exponential back off in the polling loop, + * up to 1/10th of the total timeout, then continue to poll at a + * constant rate up to the timeout. + */ + delay = 1; + while ((iicstat & S3C2410_IICSTAT_START) && + ktime_us_delta(now, start) < S3C2410_IDLE_TIMEOUT) { + usleep_range(delay, 2 * delay); + if (delay < S3C2410_IDLE_TIMEOUT / 10) + delay <<= 1; + now = ktime_get(); + iicstat = readl(i2c->regs + S3C2410_IICSTAT); + } + + if (iicstat & S3C2410_IICSTAT_START) + dev_warn(i2c->dev, "timeout waiting for bus idle\n"); } /* s3c24xx_i2c_doxfer @@ -526,8 +606,7 @@ static int s3c24xx_i2c_set_master(struct s3c24xx_i2c *i2c) static int s3c24xx_i2c_doxfer(struct s3c24xx_i2c *i2c, struct i2c_msg *msgs, int num) { - unsigned long iicstat, timeout; - int spins = 20; + unsigned long timeout; int ret; if (i2c->suspended) @@ -540,8 +619,6 @@ static int s3c24xx_i2c_doxfer(struct s3c24xx_i2c *i2c, goto out; } - spin_lock_irq(&i2c->lock); - i2c->msg = msgs; i2c->msg_num = num; i2c->msg_ptr = 0; @@ -550,7 +627,6 @@ static int s3c24xx_i2c_doxfer(struct s3c24xx_i2c *i2c, 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); @@ -564,24 +640,11 @@ static int s3c24xx_i2c_doxfer(struct s3c24xx_i2c *i2c, 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 { - cpu_relax(); - 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); - } + /* For QUIRK_HDMIPHY, bus is already disabled */ + if (i2c->quirks & QUIRK_HDMIPHY) + goto out; - if (iicstat & S3C2410_IICSTAT_START) - dev_warn(i2c->dev, "timeout waiting for bus idle\n"); + s3c24xx_i2c_wait_idle(i2c); out: return ret; @@ -740,7 +803,6 @@ 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; @@ -754,9 +816,9 @@ static int s3c24xx_i2c_cpufreq_transition(struct notifier_block *nb, if ((val == CPUFREQ_POSTCHANGE && delta_f < 0) || (val == CPUFREQ_PRECHANGE && delta_f > 0)) { - spin_lock_irqsave(&i2c->lock, flags); + i2c_lock_adapter(&i2c->adap); ret = s3c24xx_i2c_clockrate(i2c, &got); - spin_unlock_irqrestore(&i2c->lock, flags); + i2c_unlock_adapter(&i2c->adap); if (ret < 0) dev_err(i2c->dev, "cannot find frequency\n"); @@ -858,14 +920,6 @@ static int s3c24xx_i2c_init(struct s3c24xx_i2c *i2c) pdata = i2c->pdata; - /* inititalise the gpio */ - - if (pdata->cfg_gpio) - pdata->cfg_gpio(to_platform_device(i2c->dev)); - else - if (s3c24xx_i2c_parse_dt_gpio(i2c)) - return -EINVAL; - /* write slave address */ writeb(pdata->slave_addr, i2c->regs + S3C2410_IICADD); @@ -963,7 +1017,6 @@ static int s3c24xx_i2c_probe(struct platform_device *pdev) 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 */ @@ -989,36 +1042,38 @@ static int s3c24xx_i2c_probe(struct platform_device *pdev) 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)); + i2c->regs = devm_request_and_ioremap(&pdev->dev, res); if (i2c->regs == NULL) { dev_err(&pdev->dev, "cannot map IO\n"); ret = -ENXIO; - goto err_ioarea; + goto err_clk; } - dev_dbg(&pdev->dev, "registers %p (%p, %p)\n", - i2c->regs, i2c->ioarea, res); + dev_dbg(&pdev->dev, "registers %p (%p)\n", + i2c->regs, res); /* setup info block for the i2c core */ i2c->adap.algo_data = i2c; i2c->adap.dev.parent = &pdev->dev; + i2c->pctrl = devm_pinctrl_get_select_default(i2c->dev); + + /* inititalise the i2c gpio lines */ + + if (i2c->pdata->cfg_gpio) { + i2c->pdata->cfg_gpio(to_platform_device(i2c->dev)); + } else if (IS_ERR(i2c->pctrl) && s3c24xx_i2c_parse_dt_gpio(i2c)) { + ret = -EINVAL; + goto err_clk; + } + /* initialise the i2c controller */ ret = s3c24xx_i2c_init(i2c); if (ret != 0) - goto err_iomap; + goto err_clk; /* find the IRQ for this unit (note, this relies on the init call to * ensure no current IRQs pending @@ -1027,7 +1082,7 @@ static int s3c24xx_i2c_probe(struct platform_device *pdev) i2c->irq = ret = platform_get_irq(pdev, 0); if (ret <= 0) { dev_err(&pdev->dev, "cannot find IRQ\n"); - goto err_iomap; + goto err_clk; } ret = request_irq(i2c->irq, s3c24xx_i2c_irq, 0, @@ -1035,7 +1090,7 @@ static int s3c24xx_i2c_probe(struct platform_device *pdev) if (ret != 0) { dev_err(&pdev->dev, "cannot claim IRQ %d\n", i2c->irq); - goto err_iomap; + goto err_clk; } ret = s3c24xx_i2c_register_cpufreq(i2c); @@ -1075,13 +1130,6 @@ static int s3c24xx_i2c_probe(struct platform_device *pdev) 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_unprepare(i2c->clk); clk_put(i2c->clk); @@ -1110,16 +1158,13 @@ static int s3c24xx_i2c_remove(struct platform_device *pdev) clk_disable_unprepare(i2c->clk); clk_put(i2c->clk); - iounmap(i2c->regs); - - release_resource(i2c->ioarea); - s3c24xx_i2c_dt_gpio_free(i2c); - kfree(i2c->ioarea); + if (pdev->dev.of_node && IS_ERR(i2c->pctrl)) + s3c24xx_i2c_dt_gpio_free(i2c); return 0; } -#ifdef CONFIG_PM +#ifdef CONFIG_PM_SLEEP static int s3c24xx_i2c_suspend_noirq(struct device *dev) { struct platform_device *pdev = to_platform_device(dev); @@ -1142,10 +1187,14 @@ static int s3c24xx_i2c_resume(struct device *dev) return 0; } +#endif +#ifdef CONFIG_PM static const struct dev_pm_ops s3c24xx_i2c_dev_pm_ops = { +#ifdef CONFIG_PM_SLEEP .suspend_noirq = s3c24xx_i2c_suspend_noirq, .resume = s3c24xx_i2c_resume, +#endif }; #define S3C24XX_DEV_PM_OPS (&s3c24xx_i2c_dev_pm_ops) |