diff mbox

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

Message ID 1469513510-1516-1-git-send-email-wxt@rock-chips.com
State New
Headers show

Commit Message

Caesar Wang July 26, 2016, 6:11 a.m. UTC
SARADC controller needs to be reset before programming it, otherwise
it will not function properly.

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
---

 .../bindings/iio/adc/rockchip-saradc.txt           |  5 +++++
 drivers/iio/adc/Kconfig                            |  1 +
 drivers/iio/adc/rockchip_saradc.c                  | 22 ++++++++++++++++++++++
 3 files changed, 28 insertions(+)

Comments

John Keeping July 26, 2016, 9 a.m. UTC | #1
On Tue, 26 Jul 2016 14:11:47 +0800, Caesar Wang wrote:

> SARADC controller needs to be reset before programming it, otherwise
> it will not function properly.
> 
> 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
> ---
> 
> diff --git a/drivers/iio/adc/rockchip_saradc.c b/drivers/iio/adc/rockchip_saradc.c
> index f9ad6c2..2f0e110 100644
> --- a/drivers/iio/adc/rockchip_saradc.c
> +++ b/drivers/iio/adc/rockchip_saradc.c
> @@ -218,6 +231,13 @@ static int rockchip_saradc_probe(struct platform_device *pdev)
>  	if (IS_ERR(info->regs))
>  		return PTR_ERR(info->regs);
>  
> +	info->reset = devm_reset_control_get(&pdev->dev, "saradc-apb");
> +	if (IS_ERR(info->reset)) {
> +		ret = PTR_ERR(info->reset);
> +		dev_err(&pdev->dev, "failed to get saradc reset: %d\n", ret);
> +		return ret;
> +	}

Does this need to handle ENOENT so as to avoid failing with old device
tree blobs?
Heiko Stübner July 26, 2016, 9:17 a.m. UTC | #2
Am Dienstag, 26. Juli 2016, 14:11:47 schrieb Caesar Wang:
> SARADC controller needs to be reset before programming it, otherwise
> it will not function properly.
> 
> 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
> ---
> 
>  .../bindings/iio/adc/rockchip-saradc.txt           |  5 +++++
>  drivers/iio/adc/Kconfig                            |  1 +
>  drivers/iio/adc/rockchip_saradc.c                  | 22
> ++++++++++++++++++++++ 3 files changed, 28 insertions(+)
> 
> diff --git a/Documentation/devicetree/bindings/iio/adc/rockchip-saradc.txt
> b/Documentation/devicetree/bindings/iio/adc/rockchip-saradc.txt index
> bf99e2f..d2258be 100644
> --- a/Documentation/devicetree/bindings/iio/adc/rockchip-saradc.txt
> +++ b/Documentation/devicetree/bindings/iio/adc/rockchip-saradc.txt
> @@ -13,6 +13,9 @@ Required properties:
>  - clocks: Must contain an entry for each entry in clock-names.
>  - clock-names: Shall be "saradc" for the converter-clock, and "apb_pclk"
> for the peripheral clock.
> +- resets: Must contain an entry for each entry in reset-names.
> +	  See ../reset/reset.txt for details.
> +- reset-names: Must include the name "saradc-apb".

as pointed out by John, this should be an optional property, as it should work 
with old devicetrees as well.
Caesar Wang July 26, 2016, 10:49 a.m. UTC | #3
On 2016年07月26日 17:00, John Keeping wrote:
> On Tue, 26 Jul 2016 14:11:47 +0800, Caesar Wang wrote:
>
>> SARADC controller needs to be reset before programming it, otherwise
>> it will not function properly.
>>
>> 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
>> ---
>>
>> diff --git a/drivers/iio/adc/rockchip_saradc.c b/drivers/iio/adc/rockchip_saradc.c
>> index f9ad6c2..2f0e110 100644
>> --- a/drivers/iio/adc/rockchip_saradc.c
>> +++ b/drivers/iio/adc/rockchip_saradc.c
>> @@ -218,6 +231,13 @@ static int rockchip_saradc_probe(struct platform_device *pdev)
>>   	if (IS_ERR(info->regs))
>>   		return PTR_ERR(info->regs);
>>   
>> +	info->reset = devm_reset_control_get(&pdev->dev, "saradc-apb");
>> +	if (IS_ERR(info->reset)) {
>> +		ret = PTR_ERR(info->reset);
>> +		dev_err(&pdev->dev, "failed to get saradc reset: %d\n", ret);
>> +		return ret;
>> +	}
> Does this need to handle ENOENT so as to avoid failing with old device
> tree blobs?

I'm no sure why we have to support the old device tree,
We can apply this series patches if we need to support the reset property.
---

Maybe, I can follow you suggestion to handle the ENOENT, as following:

+ /*
+ * 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)) {
+ if (PTR_ERR(info->reset) == -EPROBE_DEFER) {
+ ret = -EPROBE_DEFER;
+ return ret;
+ }
+ dev_dbg(&pdev->dev, "no reset control found\n");
+ info->reset = NULL;
+ }
...

+ if (info->reset)
+ rockchip_saradc_reset_controller(info->reset);
+

How about it?


-
Caesar
>
> _______________________________________________
> Linux-rockchip mailing list
> Linux-rockchip@lists.infradead.org
> http://lists.infradead.org/mailman/listinfo/linux-rockchip
John Keeping July 26, 2016, 11:16 a.m. UTC | #4
On Tue, 26 Jul 2016 18:49:56 +0800, Caesar Wang wrote:

> 
> On 2016年07月26日 17:00, John Keeping wrote:
> > On Tue, 26 Jul 2016 14:11:47 +0800, Caesar Wang wrote:
> >
> >> SARADC controller needs to be reset before programming it, otherwise
> >> it will not function properly.
> >>
> >> 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
> >> ---
> >>
> >> diff --git a/drivers/iio/adc/rockchip_saradc.c b/drivers/iio/adc/rockchip_saradc.c
> >> index f9ad6c2..2f0e110 100644
> >> --- a/drivers/iio/adc/rockchip_saradc.c
> >> +++ b/drivers/iio/adc/rockchip_saradc.c
> >> @@ -218,6 +231,13 @@ static int rockchip_saradc_probe(struct platform_device *pdev)
> >>   	if (IS_ERR(info->regs))
> >>   		return PTR_ERR(info->regs);
> >>   
> >> +	info->reset = devm_reset_control_get(&pdev->dev, "saradc-apb");
> >> +	if (IS_ERR(info->reset)) {
> >> +		ret = PTR_ERR(info->reset);
> >> +		dev_err(&pdev->dev, "failed to get saradc reset: %d\n", ret);
> >> +		return ret;
> >> +	}
> > Does this need to handle ENOENT so as to avoid failing with old device
> > tree blobs?
> 
> I'm no sure why we have to support the old device tree,
> We can apply this series patches if we need to support the reset property.
> ---
> 
> Maybe, I can follow you suggestion to handle the ENOENT, as following:
> 
> + /*
> + * 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)) {
> + if (PTR_ERR(info->reset) == -EPROBE_DEFER) {
> + ret = -EPROBE_DEFER;
> + return ret;
> + }
> + dev_dbg(&pdev->dev, "no reset control found\n");
> + info->reset = NULL;
> + }
> ...
> 
> How about it?

I think it's better to handle ENOENT specifically, we still want to fail
if some other errors like EINVAL is returned.

Something like this, perhaps?

    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;
    }

Although I do wonder if a devm_reset_control_get_optional() helper would
be useful (this isn't the first time I've seen reset control added to
existing drivers).
diff mbox

Patch

diff --git a/Documentation/devicetree/bindings/iio/adc/rockchip-saradc.txt b/Documentation/devicetree/bindings/iio/adc/rockchip-saradc.txt
index bf99e2f..d2258be 100644
--- a/Documentation/devicetree/bindings/iio/adc/rockchip-saradc.txt
+++ b/Documentation/devicetree/bindings/iio/adc/rockchip-saradc.txt
@@ -13,6 +13,9 @@  Required properties:
 - clocks: Must contain an entry for each entry in clock-names.
 - clock-names: Shall be "saradc" for the converter-clock, and "apb_pclk" for
                the peripheral clock.
+- resets: Must contain an entry for each entry in reset-names.
+	  See ../reset/reset.txt for details.
+- reset-names: Must include the name "saradc-apb".
 - vref-supply: The regulator supply ADC reference voltage.
 - #io-channel-cells: Should be 1, see ../iio-bindings.txt
 
@@ -23,6 +26,8 @@  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..2f0e110 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 +231,13 @@  static int rockchip_saradc_probe(struct platform_device *pdev)
 	if (IS_ERR(info->regs))
 		return PTR_ERR(info->regs);
 
+	info->reset = devm_reset_control_get(&pdev->dev, "saradc-apb");
+	if (IS_ERR(info->reset)) {
+		ret = PTR_ERR(info->reset);
+		dev_err(&pdev->dev, "failed to get saradc reset: %d\n", ret);
+		return ret;
+	}
+
 	init_completion(&info->completion);
 
 	irq = platform_get_irq(pdev, 0);
@@ -252,6 +272,8 @@  static int rockchip_saradc_probe(struct platform_device *pdev)
 		return PTR_ERR(info->vref);
 	}
 
+	rockchip_saradc_reset_controller(info->reset);
+
 	/*
 	 * Use a default value for the converter clock.
 	 * This may become user-configurable in the future.