Subject: [PATCH v3 1/6] i2c: s3c2410: Handle i2c sys_cfg register in i2c driver

From: [email-masked] (Pankaj Dubey)
Date: Tue, 17 Jun 2014 09:51:39 +0530

Hi Tomasz,

> 
> 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 <[email-masked]>
> > CC: Randy Dunlap <[email-masked]>
> > CC: Wolfram Sang <[email-masked]>
> > CC: Russell King <[email-masked]>
> > CC: devicetree at vger.kernel.org
> > CC: linux-doc at vger.kernel.org
> > CC: linux-i2c at vger.kernel.org
> > Signed-off-by: Pankaj Dubey <[email-masked]>
> > ---
> >  .../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?

OK, I will check user manuals of these two SoCs and if required will update.

> 
> >  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/

Oops, sorry I will correct this. 

> 
> >  };
> >
> >  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?

It's a 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.

OK, I will take care as per suggestion.

> 
> >  }
> >  #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.

Yes. I will correct this.

> Best regards,
> Tomasz