Re: [PATCH 2/4] i2c: i2c-ocores: Use reg-shift property

[Wolfram Sang <w.sang-bIcnvbaLZ9MEGnE8C9+IrQ@public.gmane.org>]

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On Tue, Jul 10, 2012 at 11:40:56AM +0530, Jayachandran C wrote:
> From: Ganesan Ramalingam <ganesanr-dY08KVG/lbpWk0Htik3J/w@public.gmane.org>
> 
> Deprecate 'regstep' property and use the standard 'reg-shift' property
> for register offset shifts. 'regstep' will still be supported as an
> optional property, but will give a warning when used.
> 
> Signed-off-by: Ganesan Ramalingam <ganesanr-dY08KVG/lbpWk0Htik3J/w@public.gmane.org>
> Signed-off-by: Jayachandran C <jayachandranc-oSioyQM9ZPnuBjGU1YDckgC/G2K4zDHf@public.gmane.org>
> ---
>  .../devicetree/bindings/i2c/i2c-ocores.txt         |    8 +++--
>  drivers/i2c/busses/i2c-ocores.c                    |   36 ++++++++++++--------
>  include/linux/i2c-ocores.h                         |    6 ++--
>  3 files changed, 31 insertions(+), 19 deletions(-)
> 
> diff --git a/Documentation/devicetree/bindings/i2c/i2c-ocores.txt b/Documentation/devicetree/bindings/i2c/i2c-ocores.txt
> index bfec894..1c9334b 100644
> --- a/Documentation/devicetree/bindings/i2c/i2c-ocores.txt
> +++ b/Documentation/devicetree/bindings/i2c/i2c-ocores.txt
> @@ -4,11 +4,14 @@ Required properties:
>  - compatible      : "opencores,i2c-ocores"
>  - reg             : bus address start and address range size of device
>  - interrupts      : interrupt number
> -- regstep         : size of device registers in bytes
>  - clock-frequency : frequency of bus clock in Hz
>  - #address-cells  : should be <1>
>  - #size-cells     : should be <0>
>  
> +Optional properties:
> +- reg-shift       : device register offsets are shifted by this value
> +- regstep         : deprecated, use reg-shift above
> +
>  Example:
>  
>  	i2c0: ocores@a0000000 {
> @@ -17,9 +20,10 @@ Example:
>  		compatible = "opencores,i2c-ocores";
>  		reg = <0xa0000000 0x8>;
>  		interrupts = <10>;
> -		regstep = <1>;
>  		clock-frequency = <20000000>;
>  
> +		reg-shift = <0>;	/* 8 bit registers */
> +
>  		dummy@60 {
>  			compatible = "dummy";
>  			reg = <0x60>;
> diff --git a/drivers/i2c/busses/i2c-ocores.c b/drivers/i2c/busses/i2c-ocores.c
> index e8159db..9617ec1 100644
> --- a/drivers/i2c/busses/i2c-ocores.c
> +++ b/drivers/i2c/busses/i2c-ocores.c
> @@ -25,10 +25,11 @@
>  #include <linux/slab.h>
>  #include <linux/io.h>
>  #include <linux/of_i2c.h>
> +#include <linux/log2.h>
>  
>  struct ocores_i2c {
>  	void __iomem *base;
> -	int regstep;
> +	int reg_shift;

Should be u32 since you use of_property_read_u32(). sparse tells you
that.

>  	wait_queue_head_t wait;
>  	struct i2c_adapter adap;
>  	struct i2c_msg *msg;
> @@ -71,12 +72,12 @@ struct ocores_i2c {
>  
>  static inline void oc_setreg(struct ocores_i2c *i2c, int reg, u8 value)
>  {
> -	iowrite8(value, i2c->base + reg * i2c->regstep);
> +	iowrite8(value, i2c->base + (reg << i2c->reg_shift));
>  }
>  
>  static inline u8 oc_getreg(struct ocores_i2c *i2c, int reg)
>  {
> -	return ioread8(i2c->base + reg * i2c->regstep);
> +	return ioread8(i2c->base + (reg << i2c->reg_shift));
>  }
>  
>  static void ocores_process(struct ocores_i2c *i2c)
> @@ -219,22 +220,29 @@ static struct i2c_adapter ocores_adapter = {
>  static int ocores_i2c_of_probe(struct platform_device *pdev,
>  				struct ocores_i2c *i2c)
>  {
> -	const __be32* val;
> -
> -	val = of_get_property(pdev->dev.of_node, "regstep", NULL);
> -	if (!val) {
> -		dev_err(&pdev->dev, "Missing required parameter 'regstep'\n");
> -		return -ENODEV;
> +	struct device_node *np = pdev->dev.of_node;
> +	u32 val;
> +
> +	if (of_property_read_u32(np, "reg-shift", &i2c->reg_shift)) {
> +		/* no 'reg-shift', check for deprecated 'regstep' */
> +		if (!of_property_read_u32(np, "regstep", &val)) {
> +			if (!is_power_of_2(val)) {
> +				dev_err(&pdev->dev, "invalid regstep %d\n",
> +					val);
> +				return -EINVAL;
> +			}
> +			i2c->reg_shift = ilog2(val);
> +			dev_warn(&pdev->dev,
> +				"regstep property deprecated, use reg-shift\n");
> +		}
>  	}
> -	i2c->regstep = be32_to_cpup(val);
>  
> -	val = of_get_property(pdev->dev.of_node, "clock-frequency", NULL);
> -	if (!val) {
> +	if (of_property_read_u32(np, "clock-frequency", &val)) {
>  		dev_err(&pdev->dev,
>  			"Missing required parameter 'clock-frequency'\n");
>  		return -ENODEV;
>  	}
> -	i2c->clock_khz = be32_to_cpup(val) / 1000;
> +	i2c->clock_khz = val / 1000;
>  
>  	return 0;
>  }
> @@ -277,7 +285,7 @@ static int __devinit ocores_i2c_probe(struct platform_device *pdev)
>  
>  	pdata = pdev->dev.platform_data;
>  	if (pdata) {
> -		i2c->regstep = pdata->regstep;
> +		i2c->reg_shift = pdata->reg_shift;
>  		i2c->clock_khz = pdata->clock_khz;
>  	} else {
>  		ret = ocores_i2c_of_probe(pdev, i2c);
> diff --git a/include/linux/i2c-ocores.h b/include/linux/i2c-ocores.h
> index 4d5e57f..bb58c7d 100644
> --- a/include/linux/i2c-ocores.h
> +++ b/include/linux/i2c-ocores.h
> @@ -12,9 +12,9 @@
>  #define _LINUX_I2C_OCORES_H
>  
>  struct ocores_i2c_platform_data {
> -	u32 regstep;   /* distance between registers */
> -	u32 clock_khz; /* input clock in kHz */
> -	u8 num_devices; /* number of devices in the devices list */
> +	u32 reg_shift;		/* register offset shift value */
> +	u32 clock_khz;		/* input clock in kHz */
> +	u8 num_devices;		/* number of devices in the devices list */

Minor: I'd like to keep the changes here minimal, so 'git blame' will be more
useful. Given the line below, indentation is not consisten anyhow.

>  	struct i2c_board_info const *devices; /* devices connected to the bus */
>  };

Thanks,

   Wolfram

-- 
Pengutronix e.K.                           | Wolfram Sang                |
Industrial Linux Solutions                 | http://www.pengutronix.de/  |

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