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

[Jonathan Cameron]

On 15/08/16 18:41, Jonathan Cameron wrote:
> On 27/07/16 15:24, Caesar Wang wrote:
>> SARADC controller needs to be reset before programming it, otherwise
>> it will not function properly.
>>
>> Signed-off-by: Caesar Wang <wxt@xxxxxxxxxxxxxx>
>> Cc: Jonathan Cameron <jic23@xxxxxxxxxx>
>> Cc: Heiko Stuebner <heiko@xxxxxxxxx>
>> Cc: Rob Herring <robh+dt@xxxxxxxxxx>
>> Cc: linux-iio@xxxxxxxxxxxxxxx
>> Cc: linux-rockchip@xxxxxxxxxxxxxxxxxxx
>> Tested-by: Guenter Roeck <linux@xxxxxxxxxxxx>
>>
> Hi
> 
> Patch is fine (I'll fix up the wording issue) however...
> 
> I'm not clear on the severity of the issue. Is this something
> we should be pushing for stable?
To add to this, it's only useful to take this for stable if we
are also fine taking the device tree updates to make it actually
do something!

> 
> Jonathan
>> ---
>>
>> 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.
>> +- 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.
>>
> 
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