[COMMON] driver: exynos_adc: add Semaphore for peterson algorithm.

The peterson algorithm is applied to prevent race condition between CHUB and AP.

Change-Id: Ic9b4790d42bcbe2ab38434a10149b1377dbc45f8
Signed-off-by: Choi Jaehyoung <jkkkkk.choi@samsung.com>

diff --git a/drivers/iio/adc/exynos_adc.c b/drivers/iio/adc/exynos_adc.c
index 8bb3419f9d4176e0ebb5c3b28d5b76e37216fd00..8d7e7227815ca3be4c7873ad7105ad6a98f2f46d 100644 (file)
--- a/drivers/iio/adc/exynos_adc.c
+++ b/drivers/iio/adc/exynos_adc.c
@@ -45,6 +45,14 @@
 
 #include <soc/samsung/exynos-powermode.h>
 
+/* Semaphore for peterson algorithm  */
+#define AP_TURN 0
+#define CHUB_TURN 1
+
+#define AP_FLAG_OFFSET         (0x3100)
+#define CHUB_FLAG_OFFSET       (0x3104)
+#define INIT_TURN_OFFSET       (0x3108)
+
 /* S3C/EXYNOS4412/5250 ADC_V1 registers definitions */
 #define ADC_V1_CON(x)          ((x) + 0x00)
 #define ADC_V1_TSC(x)          ((x) + 0x04)
@@ -141,6 +149,7 @@ struct exynos_adc {
        struct device           *dev;
        struct input_dev        *input;
        void __iomem            *regs;
+       void __iomem            *cmgp_sysreg;
        struct regmap           *pmu_map;
        struct clk              *clk;
        struct clk              *sclk;
@@ -638,9 +647,26 @@ static int exynos_read_raw(struct iio_dev *indio_dev,
                                long mask)
 {
        struct exynos_adc *info = iio_priv(indio_dev);
-       unsigned long timeout;
+       unsigned long timeout, sysreg_timeout = 0;
        int ret;
 
+       if (info->cmgp_sysreg) {
+               __raw_writel(true, info->cmgp_sysreg + AP_FLAG_OFFSET);
+               __raw_writel(CHUB_TURN, info->cmgp_sysreg + INIT_TURN_OFFSET);
+               while ((__raw_readl(info->cmgp_sysreg + CHUB_FLAG_OFFSET) == true)
+                               && (__raw_readl(info->cmgp_sysreg + INIT_TURN_OFFSET) == CHUB_TURN)
+                               && (sysreg_timeout < 100)) {
+                       /* If CHUB does not use ADC or timeout value is 100, this loop end. */
+                       mdelay(1);
+                       sysreg_timeout++;
+               }
+               if (sysreg_timeout >= 100) {
+                       dev_err(&indio_dev->dev, "Time out! Adc is currently being used by CHUB.\n");
+                       return -ETIMEDOUT;
+               }
+       }
+
+       /* critical section start */
        if (mask != IIO_CHAN_INFO_RAW)
                return -EINVAL;
 
@@ -678,6 +704,11 @@ static int exynos_read_raw(struct iio_dev *indio_dev,
 err_unlock:
        mutex_unlock(&indio_dev->mlock);
 
+
+       /* critical section end */
+       if (info->cmgp_sysreg)
+               __raw_writel(false, info->cmgp_sysreg + AP_FLAG_OFFSET);
+
        return ret;
 }
 
@@ -911,6 +942,7 @@ static int exynos_adc_probe(struct platform_device *pdev)
        bool has_ts = false;
        int ret = -ENODEV;
        int irq;
+       unsigned int sysreg;
 
        indio_dev = devm_iio_device_alloc(&pdev->dev, sizeof(struct exynos_adc));
        if (!indio_dev) {
@@ -931,6 +963,17 @@ static int exynos_adc_probe(struct platform_device *pdev)
        else
                info->needs_adc_phy = false;
 
+       if (of_property_read_u32(np, "sysreg", &sysreg)) {
+               dev_info(&pdev->dev, "Do not use Peterson algorithm\n");
+               info->cmgp_sysreg = NULL;
+       } else {
+               info->cmgp_sysreg = devm_ioremap(&pdev->dev, sysreg, SZ_64K);
+               if (IS_ERR(info->cmgp_sysreg)) {
+                       dev_err(&pdev->dev, "Failed devm_ioremap\n");
+                       return PTR_ERR(info->cmgp_sysreg);
+               }
+       }
+
        mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
        info->regs = devm_ioremap_resource(&pdev->dev, mem);
        if (IS_ERR(info->regs))