linux-kernel - Re: [PATCH v3 1/6] i2c: s3c2410: Handle i2c sys

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Date:	Tue, 10 Jun 2014 15:35:16 +0200
From:	Tomasz Figa <t.figa@...sung.com>
To:	Pankaj Dubey <pankaj.dubey@...sung.com>,
	linux-samsung-soc@...r.kernel.org, linux-kernel@...r.kernel.org,
	linux-arm-kernel@...ts.infradead.org
Cc:	kgene.kim@...sung.com, arnd@...db.de,
	Rob Herring <robh+dt@...nel.org>,
	Randy Dunlap <rdunlap@...radead.org>,
	Wolfram Sang <wsa@...-dreams.de>,
	Russell King <linux@....linux.org.uk>,
	devicetree@...r.kernel.org, linux-doc@...r.kernel.org,
	linux-i2c@...r.kernel.org
Subject: Re: [PATCH v3 1/6] i2c: s3c2410: Handle i2c sys_cfg register in i2c
 driver

Hi Pankaj,

On 10.05.2014 09:20, Pankaj Dubey wrote:
> Let's handle i2c interrupt re-configuration in i2c driver. This will
> help us in removing some soc specific checks from machine files.
> Since only Exynos5250, and Exynos5420 need to do this, added syscon
> based phandle to i2c device nodes of respective SoC DT files.
> Also handle saving and restoring of SYS_I2C_CFG register during
> suspend and resume of i2c driver. This will help in removing soc
> specific check from mach-exynos/pm.c.
> 
> CC: Rob Herring <robh+dt@...nel.org>
> CC: Randy Dunlap <rdunlap@...radead.org>
> CC: Wolfram Sang <wsa@...-dreams.de>
> CC: Russell King <linux@....linux.org.uk>
> CC: devicetree@...r.kernel.org
> CC: linux-doc@...r.kernel.org
> CC: linux-i2c@...r.kernel.org
> Signed-off-by: Pankaj Dubey <pankaj.dubey@...sung.com>
> ---
>  .../devicetree/bindings/arm/samsung/sysreg.txt     |    1 +
>  arch/arm/boot/dts/exynos5.dtsi                     |    5 +++
>  arch/arm/boot/dts/exynos5250.dtsi                  |    4 +++
>  arch/arm/boot/dts/exynos5420.dtsi                  |    4 +++

What about Exynos5410 and Exynos5800?

>  drivers/i2c/busses/i2c-s3c2410.c                   |   32 ++++++++++++++++++++
>  5 files changed, 46 insertions(+)

[snip]

> diff --git a/drivers/i2c/busses/i2c-s3c2410.c b/drivers/i2c/busses/i2c-s3c2410.c
> index ae44910..e707062 100644
> --- a/drivers/i2c/busses/i2c-s3c2410.c
> +++ b/drivers/i2c/busses/i2c-s3c2410.c
> @@ -39,6 +39,8 @@
>  #include <linux/of.h>
>  #include <linux/of_gpio.h>
>  #include <linux/pinctrl/consumer.h>
> +#include <linux/mfd/syscon.h>
> +#include <linux/regmap.h>
>  
>  #include <asm/irq.h>
>  
> @@ -91,6 +93,9 @@
>  /* Max time to wait for bus to become idle after a xfer (in us) */
>  #define S3C2410_IDLE_TIMEOUT	5000
>  
> +/* Exynos5 Sysreg offset */
> +#define EXYNOS5_SYS_I2C_CFG	0x0234
> +
>  /* i2c controller state */
>  enum s3c24xx_i2c_state {
>  	STATE_IDLE,
> @@ -127,6 +132,8 @@ struct s3c24xx_i2c {
>  #if defined(CONFIG_ARM_S3C24XX_CPUFREQ)
>  	struct notifier_block	freq_transition;
>  #endif
> +	struct regmap		*sysreg;
> +	unsigned int		sys_i2s_cfg;

typo: s/i2s/i2c/

>  };
>  
>  static struct platform_device_id s3c24xx_driver_ids[] = {
> @@ -1075,6 +1082,8 @@ static void
>  s3c24xx_i2c_parse_dt(struct device_node *np, struct s3c24xx_i2c *i2c)
>  {
>  	struct s3c2410_platform_i2c *pdata = i2c->pdata;
> +	u32 val = 0;
> +	int id;
>  
>  	if (!np)
>  		return;
> @@ -1084,6 +1093,23 @@ s3c24xx_i2c_parse_dt(struct device_node *np, struct s3c24xx_i2c *i2c)
>  	of_property_read_u32(np, "samsung,i2c-slave-addr", &pdata->slave_addr);
>  	of_property_read_u32(np, "samsung,i2c-max-bus-freq",
>  				(u32 *)&pdata->frequency);
> +	/*
> +	 * Exynos5's legacy i2c controller and new high speed i2c
> +	 * controller have muxed interrupt sources. By default the

What do you mean by "by default"? Is it a setting from the bootloader or
reset value?

Probably to ensure that the mux is set correctly, same thing should be
also added to hsi2c driver.

> +	 * interrupts for 4-channel HS-I2C controller are enabled.
> +	 * If node for first four channels of legacy i2c controller
> +	 * are available then re-configure the interrupts via the
> +	 * system register.
> +	 */
> +	id = of_alias_get_id(np, "i2c");
> +	i2c->sysreg = syscon_regmap_lookup_by_phandle(np,
> +			"samsung,syscon-phandle");
> +	if (IS_ERR(i2c->sysreg)) {
> +		/* As this is not compulsory do not return error */
> +		pr_info("i2c-%d skipping re-configuration of interrutps\n", id);
> +		return;
> +	}
> +	regmap_update_bits(i2c->sysreg, EXYNOS5_SYS_I2C_CFG, BIT(id), val);

As Wolfram pointed, val can be replaced with immediate 0 here.

>  }
>  #else
>  static void
> @@ -1268,6 +1294,9 @@ static int s3c24xx_i2c_suspend_noirq(struct device *dev)
>  
>  	i2c->suspended = 1;
>  
> +	if (!IS_ERR(i2c->sysreg))
> +		regmap_read(i2c->sysreg, EXYNOS5_SYS_I2C_CFG, &i2c->sys_i2s_cfg);
> +
>  	return 0;
>  }
>  
> @@ -1276,6 +1305,9 @@ static int s3c24xx_i2c_resume(struct device *dev)
>  	struct platform_device *pdev = to_platform_device(dev);
>  	struct s3c24xx_i2c *i2c = platform_get_drvdata(pdev);
>  
> +	if (!IS_ERR(i2c->sysreg))
> +		regmap_write(i2c->sysreg, i2c->sys_i2s_cfg, EXYNOS5_SYS_I2C_CFG);

According to include/linux/regmap.h:

int regmap_write(struct regmap *map, unsigned int reg, unsigned int val);

So in your code reg is swapped with val.

Best regards,
Tomasz
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