Re: [PATCH v3 1/4] iio: adc: rockchip_saradc: reset saradc controller before programming it

Peter Meerwald-Stadler
2016-07-27T14:47:48Z

> SARADC controller needs to be reset before programming it, otherwise
> it will not function properly.

nitpicking on wording below

> Signed-off-by: Caesar Wang <wxt@rock-chips.com>
> Cc: Jonathan Cameron <jic23@kernel.org>
> Cc: Heiko Stuebner <heiko@sntech.de>
> Cc: Rob Herring <robh+dt@kernel.org>
> Cc: linux-iio@vger.kernel.org
> Cc: linux-rockchip@lists.infradead.org
> Tested-by: Guenter Roeck <linux@roeck-us.net>
>
> ---
>
> Changes in v3:
> - %s/devm_reset_control_get_optional()/devm_reset_control_get()
> - add Guente's test tag.
>
> Changes in v2:
> - Make the reset as an optional property, since it should work
> with old devicetrees as well.
>
> .../bindings/iio/adc/rockchip-saradc.txt | 7 +++++
> drivers/iio/adc/Kconfig | 1 +
> drivers/iio/adc/rockchip_saradc.c | 30 ++++++++++++++++++++++
> 3 files changed, 38 insertions(+)
>
> diff --git a/Documentation/devicetree/bindings/iio/adc/rockchip-saradc.txt b/Documentation/devicetree/bindings/iio/adc/rockchip-saradc.txt
> index bf99e2f..205593f 100644
> --- a/Documentation/devicetree/bindings/iio/adc/rockchip-saradc.txt
> +++ b/Documentation/devicetree/bindings/iio/adc/rockchip-saradc.txt
> @@ -16,6 +16,11 @@ Required properties:
> - vref-supply: The regulator supply ADC reference voltage.
> - #io-channel-cells: Should be 1, see ../iio-bindings.txt
>
> +Optional properties:
> +- resets: Must contain an entry for each entry in reset-names if need support
> + this option. See ../reset/reset.txt for details.

'... if need support this option.' doesn't sound right, maybe
simply: '... if needed.' or drop this clause.

> +- reset-names: Must include the name "saradc-apb".
> +
> Example:
> saradc: saradc@2006c000 {
> compatible = "rockchip,saradc";
> @@ -23,6 +28,8 @@ Example:
> interrupts = <GIC_SPI 26 IRQ_TYPE_LEVEL_HIGH>;
> clocks = <&cru SCLK_SARADC>, <&cru PCLK_SARADC>;
> clock-names = "saradc", "apb_pclk";
> + resets = <&cru SRST_SARADC>;
> + reset-names = "saradc-apb";
> #io-channel-cells = <1>;
> vref-supply = <&vcc18>;
> };
> diff --git a/drivers/iio/adc/Kconfig b/drivers/iio/adc/Kconfig
> index 1de31bd..7675772 100644
> --- a/drivers/iio/adc/Kconfig
> +++ b/drivers/iio/adc/Kconfig
> @@ -389,6 +389,7 @@ config QCOM_SPMI_VADC
> config ROCKCHIP_SARADC
> tristate "Rockchip SARADC driver"
> depends on ARCH_ROCKCHIP || (ARM && COMPILE_TEST)
> + depends on RESET_CONTROLLER
> help
> Say yes here to build support for the SARADC found in SoCs from
> Rockchip.
> diff --git a/drivers/iio/adc/rockchip_saradc.c b/drivers/iio/adc/rockchip_saradc.c
> index f9ad6c2..85d7012 100644
> --- a/drivers/iio/adc/rockchip_saradc.c
> +++ b/drivers/iio/adc/rockchip_saradc.c
> @@ -21,6 +21,8 @@
> #include <linux/of_device.h>
> #include <linux/clk.h>
> #include <linux/completion.h>
> +#include <linux/delay.h>
> +#include <linux/reset.h>
> #include <linux/regulator/consumer.h>
> #include <linux/iio/iio.h>
>
> @@ -53,6 +55,7 @@ struct rockchip_saradc {
> struct clk *clk;
> struct completion completion;
> struct regulator *vref;
> + struct reset_control *reset;
> const struct rockchip_saradc_data *data;
> u16 last_val;
> };
> @@ -190,6 +193,16 @@ static const struct of_device_id rockchip_saradc_match[] = {
> };
> MODULE_DEVICE_TABLE(of, rockchip_saradc_match);
>
> +/**
> + * Reset SARADC Controller.
> + */
> +static void rockchip_saradc_reset_controller(struct reset_control *reset)
> +{
> + reset_control_assert(reset);
> + usleep_range(10, 20);
> + reset_control_deassert(reset);
> +}
> +
> static int rockchip_saradc_probe(struct platform_device *pdev)
> {
> struct rockchip_saradc *info = NULL;
> @@ -218,6 +231,20 @@ static int rockchip_saradc_probe(struct platform_device *pdev)
> if (IS_ERR(info->regs))
> return PTR_ERR(info->regs);
>
> + /*
> + * The reset should be an optional property, as it should work
> + * with old devicetrees as well
> + */
> + info->reset = devm_reset_control_get(&pdev->dev, "saradc-apb");
> + if (IS_ERR(info->reset)) {
> + ret = PTR_ERR(info->reset);
> + if (ret != -ENOENT)
> + return ret;
> +
> + dev_dbg(&pdev->dev, "no reset control found\n");
> + info->reset = NULL;
> + }
> +
> init_completion(&info->completion);
>
> irq = platform_get_irq(pdev, 0);
> @@ -252,6 +279,9 @@ static int rockchip_saradc_probe(struct platform_device *pdev)
> return PTR_ERR(info->vref);
> }
>
> + if (info->reset)
> + rockchip_saradc_reset_controller(info->reset);
> +
> /*
> * Use a default value for the converter clock.
> * This may become user-configurable in the future.
>

--

Peter Meerwald-Stadler
+43-664-2444418 (mobile)