[PATCH V2] i2c: s3c2410 : Add polling mode support

Yuvaraj Kumar yuvaraj.cd at gmail.com
Fri Dec 13 04:21:13 EST 2013


Dear Wolfram,
 Can you take this into your tree?

On Fri, Nov 22, 2013 at 11:32 AM, Yuvaraj Kumar <yuvaraj.cd at gmail.com> wrote:
> Any comments on this patch?
>
> On Mon, Nov 11, 2013 at 4:50 PM, Yuvaraj Kumar C D <yuvaraj.cd at gmail.com> wrote:
>> From: Vasanth Ananthan <vasanthananthan at gmail.com>
>>
>> This patch adds polling mode support for i2c-s3c2410 driver.The
>> SATA PHY controller's CMU and TRSV block's are of I2C register
>> map in exynos5250.These blocks can be configured using i2c.
>>
>> But i2c controller instance on which these block's sits lacks an
>> interrupt line.Also the current i2c-s3c2410 driver is only interrupt
>> driven, thus a polling mode support is required in the driver for
>> supporting this controller. This patch adds this support to the driver.
>>
>> Changes from V1:
>>         1.Changed the is_ack() to have even period b/w polls and
>>           used usleep_range() instead of udelay().
>>
>> Signed-off-by: Vasanth Ananthan <vasanth.a at samsung.com>
>> Signed-off-by: Yuvaraj Kumar C D <yuvaraj.cd at samsung.com>
>> ---
>>  .../devicetree/bindings/i2c/i2c-s3c2410.txt        |    2 +
>>  drivers/i2c/busses/i2c-s3c2410.c                   |   66 +++++++++++++++++---
>>  2 files changed, 58 insertions(+), 10 deletions(-)
>>
>> diff --git a/Documentation/devicetree/bindings/i2c/i2c-s3c2410.txt b/Documentation/devicetree/bindings/i2c/i2c-s3c2410.txt
>> index 296eb45..278de8e 100644
>> --- a/Documentation/devicetree/bindings/i2c/i2c-s3c2410.txt
>> +++ b/Documentation/devicetree/bindings/i2c/i2c-s3c2410.txt
>> @@ -10,6 +10,8 @@ Required properties:
>>            inside HDMIPHY block found on several samsung SoCs
>>        (d) "samsung, exynos5440-i2c", for s3c2440-like i2c used
>>            on EXYNOS5440 which does not need GPIO configuration.
>> +      (e) "samsung, exynos5-sata-phy-i2c", for s3c2440-like i2c used as
>> +          a host to SATA PHY controller on an internal bus.
>>    - reg: physical base address of the controller and length of memory mapped
>>      region.
>>    - interrupts: interrupt number to the cpu.
>> diff --git a/drivers/i2c/busses/i2c-s3c2410.c b/drivers/i2c/busses/i2c-s3c2410.c
>> index 3747b9b..08ed126 100644
>> --- a/drivers/i2c/busses/i2c-s3c2410.c
>> +++ b/drivers/i2c/busses/i2c-s3c2410.c
>> @@ -85,6 +85,7 @@
>>  #define QUIRK_S3C2440          (1 << 0)
>>  #define QUIRK_HDMIPHY          (1 << 1)
>>  #define QUIRK_NO_GPIO          (1 << 2)
>> +#define QUIRK_POLL             (1 << 3)
>>
>>  /* Max time to wait for bus to become idle after a xfer (in us) */
>>  #define S3C2410_IDLE_TIMEOUT   5000
>> @@ -141,6 +142,8 @@ static struct platform_device_id s3c24xx_driver_ids[] = {
>>  };
>>  MODULE_DEVICE_TABLE(platform, s3c24xx_driver_ids);
>>
>> +static int i2c_s3c_irq_nextbyte(struct s3c24xx_i2c *i2c, unsigned long iicstat);
>> +
>>  #ifdef CONFIG_OF
>>  static const struct of_device_id s3c24xx_i2c_match[] = {
>>         { .compatible = "samsung,s3c2410-i2c", .data = (void *)0 },
>> @@ -149,6 +152,8 @@ static const struct of_device_id s3c24xx_i2c_match[] = {
>>           .data = (void *)(QUIRK_S3C2440 | QUIRK_HDMIPHY | QUIRK_NO_GPIO) },
>>         { .compatible = "samsung,exynos5440-i2c",
>>           .data = (void *)(QUIRK_S3C2440 | QUIRK_NO_GPIO) },
>> +       { .compatible = "samsung,exynos5-sata-phy-i2c",
>> +         .data = (void *)(QUIRK_S3C2440 | QUIRK_POLL | QUIRK_NO_GPIO) },
>>         {},
>>  };
>>  MODULE_DEVICE_TABLE(of, s3c24xx_i2c_match);
>> @@ -187,7 +192,8 @@ static inline void s3c24xx_i2c_master_complete(struct s3c24xx_i2c *i2c, int ret)
>>         if (ret)
>>                 i2c->msg_idx = ret;
>>
>> -       wake_up(&i2c->wait);
>> +       if (!(i2c->quirks & QUIRK_POLL))
>> +               wake_up(&i2c->wait);
>>  }
>>
>>  static inline void s3c24xx_i2c_disable_ack(struct s3c24xx_i2c *i2c)
>> @@ -224,6 +230,22 @@ static inline void s3c24xx_i2c_enable_irq(struct s3c24xx_i2c *i2c)
>>         writel(tmp | S3C2410_IICCON_IRQEN, i2c->regs + S3C2410_IICCON);
>>  }
>>
>> +static bool is_ack(struct s3c24xx_i2c *i2c)
>> +{
>> +       int tries;
>> +
>> +       for (tries = 50; tries; --tries) {
>> +               if (readl(i2c->regs + S3C2410_IICCON)
>> +                       & S3C2410_IICCON_IRQPEND) {
>> +                       if (!(readl(i2c->regs + S3C2410_IICSTAT)
>> +                               & S3C2410_IICSTAT_LASTBIT))
>> +                               return true;
>> +               }
>> +               usleep_range(1000, 2000);
>> +       }
>> +       dev_err(i2c->dev, "ack was not recieved\n");
>> +       return false;
>> +}
>>
>>  /* s3c24xx_i2c_message_start
>>   *
>> @@ -268,6 +290,16 @@ static void s3c24xx_i2c_message_start(struct s3c24xx_i2c *i2c,
>>
>>         stat |= S3C2410_IICSTAT_START;
>>         writel(stat, i2c->regs + S3C2410_IICSTAT);
>> +
>> +       if (i2c->quirks & QUIRK_POLL) {
>> +               while ((i2c->msg_num != 0) && is_ack(i2c)) {
>> +                       i2c_s3c_irq_nextbyte(i2c, stat);
>> +                       stat = readl(i2c->regs + S3C2410_IICSTAT);
>> +
>> +                       if (stat & S3C2410_IICSTAT_ARBITR)
>> +                               dev_err(i2c->dev, "deal with arbitration loss\n");
>> +               }
>> +       }
>>  }
>>
>>  static inline void s3c24xx_i2c_stop(struct s3c24xx_i2c *i2c, int ret)
>> @@ -675,6 +707,15 @@ static int s3c24xx_i2c_doxfer(struct s3c24xx_i2c *i2c,
>>         s3c24xx_i2c_enable_irq(i2c);
>>         s3c24xx_i2c_message_start(i2c, msgs);
>>
>> +       if (i2c->quirks & QUIRK_POLL) {
>> +               ret = i2c->msg_idx;
>> +
>> +               if (ret != num)
>> +                       dev_dbg(i2c->dev, "incomplete xfer (%d)\n", ret);
>> +
>> +               goto out;
>> +       }
>> +
>>         timeout = wait_event_timeout(i2c->wait, i2c->msg_num == 0, HZ * 5);
>>
>>         ret = i2c->msg_idx;
>> @@ -820,6 +861,9 @@ static int s3c24xx_i2c_clockrate(struct s3c24xx_i2c *i2c, unsigned int *got)
>>         if (div1 == 512)
>>                 iiccon |= S3C2410_IICCON_TXDIV_512;
>>
>> +       if (i2c->quirks & QUIRK_POLL)
>> +               iiccon |= S3C2410_IICCON_SCALE(2);
>> +
>>         writel(iiccon, i2c->regs + S3C2410_IICCON);
>>
>>         if (i2c->quirks & QUIRK_S3C2440) {
>> @@ -1117,18 +1161,20 @@ static int s3c24xx_i2c_probe(struct platform_device *pdev)
>>          * ensure no current IRQs pending
>>          */
>>
>> -       i2c->irq = ret = platform_get_irq(pdev, 0);
>> -       if (ret <= 0) {
>> -               dev_err(&pdev->dev, "cannot find IRQ\n");
>> -               return ret;
>> -       }
>> +       if (!(i2c->quirks & QUIRK_POLL)) {
>> +               i2c->irq = ret = platform_get_irq(pdev, 0);
>> +               if (ret <= 0) {
>> +                       dev_err(&pdev->dev, "cannot find IRQ\n");
>> +                       return ret;
>> +               }
>>
>>         ret = devm_request_irq(&pdev->dev, i2c->irq, s3c24xx_i2c_irq, 0,
>> -                              dev_name(&pdev->dev), i2c);
>> +                               dev_name(&pdev->dev), i2c);
>>
>> -       if (ret != 0) {
>> -               dev_err(&pdev->dev, "cannot claim IRQ %d\n", i2c->irq);
>> -               return ret;
>> +               if (ret != 0) {
>> +                       dev_err(&pdev->dev, "cannot claim IRQ %d\n", i2c->irq);
>> +                       return ret;
>> +               }
>>         }
>>
>>         ret = s3c24xx_i2c_register_cpufreq(i2c);
>> --
>> 1.7.9.5
>>



More information about the linux-arm-kernel mailing list