[PATCH 1/2 V2] MXS: Set I2C timing registers for mxs-i2c

[Shubhrajyoti Datta]

On Sat, Jun 9, 2012 at 12:24 AM, Marek Vasut <marex at denx.de> wrote:
> This patch configures the I2C bus timing registers according
> to information passed via DT. Currently, 100kHz and 400kHz
> modes are supported.
>
> Signed-off-by: Marek Vasut <marex at denx.de>
> Cc: Detlev Zundel <dzu at denx.de>
> CC: Dong Aisheng <b29396 at freescale.com>
> CC: Fabio Estevam <fabio.estevam at freescale.com>
> Cc: Linux ARM kernel <linux-arm-kernel at lists.infradead.org>
> Cc: linux-i2c at vger.kernel.org
> CC: Sascha Hauer <s.hauer at pengutronix.de>
> CC: Shawn Guo <shawn.guo at linaro.org>
> Cc: Stefano Babic <sbabic at denx.de>
> CC: Uwe Kleine-König <u.kleine-koenig at pengutronix.de>
> Cc: Wolfgang Denk <wd at denx.de>
> Cc: Wolfram Sang <w.sang at pengutronix.de>
> ---
>  Documentation/devicetree/bindings/i2c/i2c-mxs.txt |    1 +
>  arch/arm/boot/dts/imx28.dtsi                      |    2 +
>  drivers/i2c/busses/i2c-mxs.c                      |   54 +++++++++++++++++++++
>  3 files changed, 57 insertions(+)
>
> V2: Use clock-frequency instead
>
> diff --git a/Documentation/devicetree/bindings/i2c/i2c-mxs.txt b/Documentation/devicetree/bindings/i2c/i2c-mxs.txt
> index 1bfc02d..d2bf750 100644
> --- a/Documentation/devicetree/bindings/i2c/i2c-mxs.txt
> +++ b/Documentation/devicetree/bindings/i2c/i2c-mxs.txt
> @@ -4,6 +4,7 @@ Required properties:
>  - compatible: Should be "fsl,<chip>-i2c"
>  - reg: Should contain registers location and length
>  - interrupts: Should contain ERROR and DMA interrupts
> +- clock-frequency: desired I2C bus clock frequency in Hz.
>
>  Examples:
>
> diff --git a/arch/arm/boot/dts/imx28.dtsi b/arch/arm/boot/dts/imx28.dtsi
> index a89da5a..714e63c 100644
> --- a/arch/arm/boot/dts/imx28.dtsi
> +++ b/arch/arm/boot/dts/imx28.dtsi
> @@ -398,6 +398,7 @@
>                                compatible = "fsl,imx28-i2c";
>                                reg = <0x80058000 2000>;
>                                interrupts = <111 68>;
> +                               clock-frequency = <400000>;
>                                status = "disabled";
>                        };
>
> @@ -407,6 +408,7 @@
>                                compatible = "fsl,imx28-i2c";
>                                reg = <0x8005a000 2000>;
>                                interrupts = <110 69>;
> +                               clock-frequency = <400000>;
>                                status = "disabled";
>                        };
>
> diff --git a/drivers/i2c/busses/i2c-mxs.c b/drivers/i2c/busses/i2c-mxs.c
> index 04eb441..b4d083f 100644
> --- a/drivers/i2c/busses/i2c-mxs.c
> +++ b/drivers/i2c/busses/i2c-mxs.c
> @@ -46,6 +46,10 @@
>  #define MXS_I2C_CTRL0_DIRECTION                        0x00010000
>  #define MXS_I2C_CTRL0_XFER_COUNT(v)            ((v) & 0x0000FFFF)
>
> +#define MXS_I2C_TIMING0                (0x10)
> +#define MXS_I2C_TIMING1                (0x20)
> +#define MXS_I2C_TIMING2                (0x30)
> +
>  #define MXS_I2C_CTRL1          (0x40)
>  #define MXS_I2C_CTRL1_SET      (0x44)
>  #define MXS_I2C_CTRL1_CLR      (0x48)
> @@ -97,6 +101,24 @@
>  #define MXS_CMD_I2C_READ       (MXS_I2C_CTRL0_SEND_NAK_ON_LAST | \
>                                 MXS_I2C_CTRL0_MASTER_MODE)
>
> +struct mxs_i2c_speed_config {
> +       uint32_t        timing0;
> +       uint32_t        timing1;
> +       uint32_t        timing2;
> +};
> +
> +const struct mxs_i2c_speed_config mxs_i2c_95kHz_config = {
You are using 95k?
Didnt understand this.


> +       .timing0        = 0x00780030,
> +       .timing1        = 0x00800030,
> +       .timing2        = 0x0015000d,
> +};
> +
> +const struct mxs_i2c_speed_config mxs_i2c_400kHz_config = {
> +       .timing0        = 0x000f0007,
> +       .timing1        = 0x001f000f,
> +       .timing2        = 0x0015000d,
> +};
> +

How are these values calculated?