Hi Marek,
On Fri, Jun 29, 2012 at 04:24:02PM +0800, Marek Vasut wrote:
> This patch configures the I2C bus timing registers according
> to information passed via DT. Currently, 100kHz and 400kHz
> modes are supported.
>
> The TIMING2 register value is wrong in the documentation for
> i.MX28! This was found and fixed by:
> Shawn Guo <shawn.guo@xxxxxxxxxx>
>
> Signed-off-by: Marek Vasut <marex@xxxxxxx>
> Cc: Detlev Zundel <dzu@xxxxxxx>
> CC: Dong Aisheng <b29396@xxxxxxxxxxxxx>
> CC: Fabio Estevam <fabio.estevam@xxxxxxxxxxxxx>
> Cc: Linux ARM kernel <linux-arm-kernel@xxxxxxxxxxxxxxxxxxx>
> Cc: linux-i2c@xxxxxxxxxxxxxxx
> CC: Sascha Hauer <s.hauer@xxxxxxxxxxxxxx>
> CC: Shawn Guo <shawn.guo@xxxxxxxxxx>
> Cc: Stefano Babic <sbabic@xxxxxxx>
> CC: Uwe Kleine-König <u.kleine-koenig@xxxxxxxxxxxxxx>
> Cc: Wolfgang Denk <wd@xxxxxxx>
> Cc: Wolfram Sang <w.sang@xxxxxxxxxxxxxx>
> ---
> Documentation/devicetree/bindings/i2c/i2c-mxs.txt | 1 +
> arch/arm/boot/dts/imx28.dtsi | 2 +
> drivers/i2c/busses/i2c-mxs.c | 56 +++++++++++++++++++++
> 3 files changed, 59 insertions(+)
>
> 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.
Is this required properties?
If yes, it may be good to also update examples.
>
> Examples:
>
> diff --git a/arch/arm/boot/dts/imx28.dtsi b/arch/arm/boot/dts/imx28.dtsi
> index ee3778a..832d30a 100644
> --- a/arch/arm/boot/dts/imx28.dtsi
> +++ b/arch/arm/boot/dts/imx28.dtsi
> @@ -419,6 +419,7 @@
> compatible = "fsl,imx28-i2c";
> reg = <0x80058000 2000>;
> interrupts = <111 68>;
> + clock-frequency = <400000>;
> status = "disabled";
> };
>
> @@ -428,6 +429,7 @@
> 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..cdcfd3f 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 +101,25 @@
> #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;
> +};
> +
> +/* Timing values for the default 24MHz clock supplied into the i2c block. */
I did not check spec,
is it possible the supplied clock changed?
> +const struct mxs_i2c_speed_config mxs_i2c_95kHz_config = {
Do we need static for it?
> + .timing0 = 0x00780030,
> + .timing1 = 0x00800030,
> + .timing2 = 0x00300030,
> +};
> +
> +const struct mxs_i2c_speed_config mxs_i2c_400kHz_config = {
ditto
> + .timing0 = 0x000f0007,
> + .timing1 = 0x001f000f,
> + .timing2 = 0x00300030,
> +};
> +
> /**
> * struct mxs_i2c_dev - per device, private MXS-I2C data
> *
> @@ -112,11 +135,17 @@ struct mxs_i2c_dev {
> struct completion cmd_complete;
> u32 cmd_err;
> struct i2c_adapter adapter;
> + const struct mxs_i2c_speed_config *speed;
> };
>
> static void mxs_i2c_reset(struct mxs_i2c_dev *i2c)
> {
> stmp_reset_block(i2c->regs);
> +
> + writel(i2c->speed->timing0, i2c->regs + MXS_I2C_TIMING0);
> + writel(i2c->speed->timing1, i2c->regs + MXS_I2C_TIMING1);
> + writel(i2c->speed->timing2, i2c->regs + MXS_I2C_TIMING2);
> +
> writel(MXS_I2C_IRQ_MASK << 8, i2c->regs + MXS_I2C_CTRL1_SET);
> writel(MXS_I2C_QUEUECTRL_PIO_QUEUE_MODE,
> i2c->regs + MXS_I2C_QUEUECTRL_SET);
> @@ -319,6 +348,28 @@ static const struct i2c_algorithm mxs_i2c_algo = {
> .functionality = mxs_i2c_func,
> };
>
> +static int mxs_i2c_get_ofdata(struct mxs_i2c_dev *i2c)
> +{
> + uint32_t speed;
> + struct device *dev = i2c->dev;
> + struct device_node *node = dev->of_node;
> + int ret;
> +
> + if (!node)
> + return -EINVAL;
> +
> + i2c->speed = &mxs_i2c_95kHz_config;
Can you explain why here is 95khz rather than 100kh?
It seems this is for 100khz below.
> + ret = of_property_read_u32(node, "clock-frequency", &speed);
> + if (ret)
> + dev_warn(dev, "No I2C speed selected, using 100kHz\n");
> + else if (speed == 400000)
> + i2c->speed = &mxs_i2c_400kHz_config;
> + else if (speed != 100000)
> + dev_warn(dev, "Invalid I2C speed selected, using 100kHz\n");
> +
> + return 0;
> +}
> +
> static int __devinit mxs_i2c_probe(struct platform_device *pdev)
> {
> struct device *dev = &pdev->dev;
> @@ -358,6 +409,11 @@ static int __devinit mxs_i2c_probe(struct platform_device *pdev)
> return err;
>
> i2c->dev = dev;
> +
> + err = mxs_i2c_get_ofdata(i2c);
> + if (err)
> + return err;
> +
> platform_set_drvdata(pdev, i2c);
>
> /* Do reset to enforce correct startup after pinmuxing */
Regards
Dong Aisheng
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