Re: [PATCH] i2c: designware-platdrv: implement bus recovery

Rob Herring
2016-04-14T17:34:52Z

On Thu, Apr 14, 2016 at 10:04:56PM +0800, Jisheng Zhang wrote:
> Implement bus recovery methods for i2c designware so we can recover
> from situations where SCL/SDA are stuck low.
>
> The recovery method is similar as i2c-imx: "config the i2c pinctrl to
> gpio mode by calling pinctrl sleep set function, and then use GPIO to
> emulate the i2c protocol to send nine dummy clock to recover i2c
> device. After recovery, set i2c pinctrl to default group setting.
>
> Signed-off-by: Jisheng Zhang <jszhang@marvell.com>
> ---
> depends on runtime pm patches
> http://lists.infradead.org/pipermail/linux-arm-kernel/2016-April/422202.html
> .../devicetree/bindings/i2c/i2c-designware.txt | 12 ++++++
> drivers/i2c/busses/i2c-designware-core.c | 6 ++-
> drivers/i2c/busses/i2c-designware-core.h | 4 ++
> drivers/i2c/busses/i2c-designware-platdrv.c | 50 ++++++++++++++++++++++
> 4 files changed, 71 insertions(+), 1 deletion(-)
>
> diff --git a/Documentation/devicetree/bindings/i2c/i2c-designware.txt b/Documentation/devicetree/bindings/i2c/i2c-designware.txt
> index fee26dc..51a55c6 100644
> --- a/Documentation/devicetree/bindings/i2c/i2c-designware.txt
> +++ b/Documentation/devicetree/bindings/i2c/i2c-designware.txt
> @@ -20,6 +20,13 @@ Optional properties :
> - i2c-sda-falling-time-ns : should contain the SDA falling time in nanoseconds.
> This value which is by default 300ns is used to compute the tHIGH period.
>
> + - scl-gpios: specify the gpio related to SCL pin
> +
> + - sda-gpios: specify the gpio related to SDA pin
> +
> + - pinctrl: add extra pinctrl to configure i2c pins to gpio function for i2c
> + bus recovery, call it "gpio" state
> +

Make these common properties in i2c.txt (and a separate patch).

> Example :
>
> i2c@f0000 {
> @@ -42,4 +49,9 @@ Example :
> i2c-sda-hold-time-ns = <300>;
> i2c-sda-falling-time-ns = <300>;
> i2c-scl-falling-time-ns = <300>;
> + pinctrl-names = "default", "gpio";
> + pinctrl-0 = <&pinctrl_i2c1_default>;
> + pinctrl-1 = <&pinctrl_i2c1_gpio>;
> + scl-gpios = <&porta 26 GPIO_ACTIVE_HIGH>;
> + sda-gpios = <&porta 27 GPIO_ACTIVE_HIGH>;
> };