[PATCH v3 0/3] Meson8 / Meson8b support for the meson_saradc driver

[PATCH v3 0/3] Meson8 / Meson8b support for the meson_saradc driver

[Martin Blumenstingl]

The SAR ADC register layout seems to be mostly the same on older SoCs.
Thus basically all functionality is already supported by the existing
driver.

There are two small differences though:
- the adc_clk and adc_div clock are not provided by the clock-controller
  on Meson8b. instead the SAR ADC provides an internal "adc_clk" (this
  behavior is already supported by the driver and requires no changes)
- the newer SoCs are using some register bits only the kernel or the
  BL30 (bootloader) are using the SAR ADC. This is the main change of
  this series: guarding all BL30 specific code with a corresponding
  "if"-block.

This also adds a new DT binding for the SAR ADC in Meson8 and Meson8b
because the driver has to specify (for this older version) that there's
no BL30 integration available (and these register bits should not be
touched).


Changes since v2 at [1]:
- re-ordered patches so patch #1 now adds the "static" modifier to the
  existing meson_sar_adc_data instances (was patch #3, now patch #1)
- dropped the "Documentation: " prefix from the devicetree
  documentation patch (patch #2)
- added Rob's ACK to the devicetree Documentation patch (patch #2)
- fixed a copy-and-paste error in the actual driver change (both,
  in the commit message where I claimed that a of_device_id was only
  added for Meson8b as well as in the driver code itself where the Meson8
  meson_sar_adc_data.name was "meson-meson8b-saradc")

Changes since v1 at [0]:
- switched to bool data-type for has_bl30_integration
- also added a "compatible" for Meson8 SoCs (the ADC driver from
  Amlogic's GPL kernel sources handles Meson8 and Meson8b identical)
- added patch #3 to constify some structs (there were supposed to be
  const from the very beginning)


[0] http://lists.infradead.org/pipermail/linux-amlogic/2017-March/003081.html
[1] http://lists.infradead.org/pipermail/linux-amlogic/2017-April/003394.html

Martin Blumenstingl (3):
  iio: adc: meson-saradc: mark all meson_sar_adc_data static and const
  dt-bindings: iio: adc: add Meson8 and Meson8b support
  iio: adc: meson-saradc: add Meson8b SoC compatibility

 .../bindings/iio/adc/amlogic,meson-saradc.txt      |  2 +
 drivers/iio/adc/meson_saradc.c                     | 86 +++++++++++++++-------
 2 files changed, 61 insertions(+), 27 deletions(-)

-- 
2.12.2

[PATCH v3 1/3] iio: adc: meson-saradc: mark all meson_sar_adc_data static and const

[Martin Blumenstingl]

These are only passed as of_device_id.data and never modified. Thus we
can mark them as static const, just like the of_device_id instances
where they are used.

Signed-off-by: Martin Blumenstingl <martin.blumenstingl@googlemail.com>
---
 drivers/iio/adc/meson_saradc.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/iio/adc/meson_saradc.c b/drivers/iio/adc/meson_saradc.c
index dd4190b50df6..1cb5df306001 100644
--- a/drivers/iio/adc/meson_saradc.c
+++ b/drivers/iio/adc/meson_saradc.c
@@ -834,17 +834,17 @@ static const struct iio_info meson_sar_adc_iio_info = {
 	.driver_module = THIS_MODULE,
 };
 
-struct meson_sar_adc_data meson_sar_adc_gxbb_data = {
+static struct meson_sar_adc_data meson_sar_adc_gxbb_data = {
 	.resolution = 10,
 	.name = "meson-gxbb-saradc",
 };
 
-struct meson_sar_adc_data meson_sar_adc_gxl_data = {
+static struct meson_sar_adc_data meson_sar_adc_gxl_data = {
 	.resolution = 12,
 	.name = "meson-gxl-saradc",
 };
 
-struct meson_sar_adc_data meson_sar_adc_gxm_data = {
+static struct meson_sar_adc_data meson_sar_adc_gxm_data = {
 	.resolution = 12,
 	.name = "meson-gxm-saradc",
 };
-- 
2.12.2

[PATCH v3 1/3] iio: adc: meson-saradc: mark all meson_sar_adc_data static and const

[Langer, Thomas]

Hello Martin,

> 
> These are only passed as of_device_id.data and never modified. Thus we
> can mark them as static const, just like the of_device_id instances
> where they are used.

Here you talk about static const, but in the code below the const is missing.

> 
> Signed-off-by: Martin Blumenstingl <martin.blumenstingl@googlemail.com>
> ---
>  drivers/iio/adc/meson_saradc.c | 6 +++---
>  1 file changed, 3 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/iio/adc/meson_saradc.c
> b/drivers/iio/adc/meson_saradc.c
> index dd4190b50df6..1cb5df306001 100644
> --- a/drivers/iio/adc/meson_saradc.c
> +++ b/drivers/iio/adc/meson_saradc.c
> @@ -834,17 +834,17 @@ static const struct iio_info meson_sar_adc_iio_info
> = {
>  	.driver_module = THIS_MODULE,
>  };
> 
> -struct meson_sar_adc_data meson_sar_adc_gxbb_data = {
> +static struct meson_sar_adc_data meson_sar_adc_gxbb_data = {
>  	.resolution = 10,
>  	.name = "meson-gxbb-saradc",
>  };
> 
> -struct meson_sar_adc_data meson_sar_adc_gxl_data = {
> +static struct meson_sar_adc_data meson_sar_adc_gxl_data = {
>  	.resolution = 12,
>  	.name = "meson-gxl-saradc",
>  };
> 
> -struct meson_sar_adc_data meson_sar_adc_gxm_data = {
> +static struct meson_sar_adc_data meson_sar_adc_gxm_data = {
>  	.resolution = 12,
>  	.name = "meson-gxm-saradc",
>  };
> --
> 2.12.2
> 

[PATCH v3 1/3] iio: adc: meson-saradc: mark all meson_sar_adc_data static and const

[Martin Blumenstingl]

Hi Thomas,

On Thu, May 4, 2017 at 9:07 PM, Langer, Thomas <thomas.langer@intel.com> wrote:
> Hello Martin,
>
>>
>> These are only passed as of_device_id.data and never modified. Thus we
>> can mark them as static const, just like the of_device_id instances
>> where they are used.
>
> Here you talk about static const, but in the code below the const is missing.
indeed - excellent catch, thank you! I'll fix this in v4

>>
>> Signed-off-by: Martin Blumenstingl <martin.blumenstingl@googlemail.com>
>> ---
>>  drivers/iio/adc/meson_saradc.c | 6 +++---
>>  1 file changed, 3 insertions(+), 3 deletions(-)
>>
>> diff --git a/drivers/iio/adc/meson_saradc.c
>> b/drivers/iio/adc/meson_saradc.c
>> index dd4190b50df6..1cb5df306001 100644
>> --- a/drivers/iio/adc/meson_saradc.c
>> +++ b/drivers/iio/adc/meson_saradc.c
>> @@ -834,17 +834,17 @@ static const struct iio_info meson_sar_adc_iio_info
>> = {
>>       .driver_module = THIS_MODULE,
>>  };
>>
>> -struct meson_sar_adc_data meson_sar_adc_gxbb_data = {
>> +static struct meson_sar_adc_data meson_sar_adc_gxbb_data = {
>>       .resolution = 10,
>>       .name = "meson-gxbb-saradc",
>>  };
>>
>> -struct meson_sar_adc_data meson_sar_adc_gxl_data = {
>> +static struct meson_sar_adc_data meson_sar_adc_gxl_data = {
>>       .resolution = 12,
>>       .name = "meson-gxl-saradc",
>>  };
>>
>> -struct meson_sar_adc_data meson_sar_adc_gxm_data = {
>> +static struct meson_sar_adc_data meson_sar_adc_gxm_data = {
>>       .resolution = 12,
>>       .name = "meson-gxm-saradc",
>>  };
>> --
>> 2.12.2
>>
>

[PATCH v3 2/3] dt-bindings: iio: adc: add Meson8 and Meson8b support

[Martin Blumenstingl]

The Amlogic Meson SAR ADC driver can be used on Meson8 and Meson8b
(probably on earlier SoC generations as well, but I don't have any
hardware available for testing that).
Add a separate compatible for Meson8 and Meson8b because it does not
need any of the BL30 magic (unlike the GX SoCs).

Signed-off-by: Martin Blumenstingl <martin.blumenstingl@googlemail.com>
Acked-by: Rob Herring <robh@kernel.org>
---
 Documentation/devicetree/bindings/iio/adc/amlogic,meson-saradc.txt | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/Documentation/devicetree/bindings/iio/adc/amlogic,meson-saradc.txt b/Documentation/devicetree/bindings/iio/adc/amlogic,meson-saradc.txt
index f9e3ff2c656e..08cee82e54c3 100644
--- a/Documentation/devicetree/bindings/iio/adc/amlogic,meson-saradc.txt
+++ b/Documentation/devicetree/bindings/iio/adc/amlogic,meson-saradc.txt
@@ -2,6 +2,8 @@
 
 Required properties:
 - compatible:	depending on the SoC this should be one of:
+			- "amlogic,meson8-saradc" for Meson8
+			- "amlogic,meson8b-saradc" for Meson8b
 			- "amlogic,meson-gxbb-saradc" for GXBB
 			- "amlogic,meson-gxl-saradc" for GXL
 			- "amlogic,meson-gxm-saradc" for GXM
-- 
2.12.2

[PATCH v3 3/3] iio: adc: meson-saradc: add Meson8b SoC compatibility

[Martin Blumenstingl]

Meson GX SoCs however use some magic bits to prevent simultaneous (=
conflicting, because only consumer should use the FIFO buffer with the
ADC results) usage by the Linux kernel and the bootloader (the BL30
bootloader uses the SAR ADC to read the CPU temperature).
This patch changes guards all BL30 functionality so it is skipped on
SoCs which don't have it. Since the hardware itself doesn't know whether
BL30 is available the internal meson_sar_adc_data is extended so this
information can be provided per of_device_id.data inside the driver.

Additionally the clocks "adc_clk" and "adc_sel" are not provided by the
clock-controller itself. "adc_sel" is not available at all. "adc_clk"
is provided by the SAR ADC IP block itself on Meson8b (and earlier).
This is already supported by the meson_saradc driver.

Finally this introduces new of_device_ids for the Meson8 and Meson8b
SoCs so the driver can be wired up in the corresponding DT.

Signed-off-by: Martin Blumenstingl <martin.blumenstingl@googlemail.com>
---
 drivers/iio/adc/meson_saradc.c | 80 +++++++++++++++++++++++++++++-------------
 1 file changed, 56 insertions(+), 24 deletions(-)

diff --git a/drivers/iio/adc/meson_saradc.c b/drivers/iio/adc/meson_saradc.c
index 1cb5df306001..611d0b7848d3 100644
--- a/drivers/iio/adc/meson_saradc.c
+++ b/drivers/iio/adc/meson_saradc.c
@@ -220,6 +220,7 @@ enum meson_sar_adc_chan7_mux_sel {
 };
 
 struct meson_sar_adc_data {
+	bool					has_bl30_integration;
 	unsigned int				resolution;
 	const char				*name;
 };
@@ -437,19 +438,24 @@ static int meson_sar_adc_lock(struct iio_dev *indio_dev)
 
 	mutex_lock(&indio_dev->mlock);
 
-	/* prevent BL30 from using the SAR ADC while we are using it */
-	regmap_update_bits(priv->regmap, MESON_SAR_ADC_DELAY,
-			   MESON_SAR_ADC_DELAY_KERNEL_BUSY,
-			   MESON_SAR_ADC_DELAY_KERNEL_BUSY);
-
-	/* wait until BL30 releases it's lock (so we can use the SAR ADC) */
-	do {
-		udelay(1);
-		regmap_read(priv->regmap, MESON_SAR_ADC_DELAY, &val);
-	} while (val & MESON_SAR_ADC_DELAY_BL30_BUSY && timeout--);
-
-	if (timeout < 0)
-		return -ETIMEDOUT;
+	if (priv->data->has_bl30_integration) {
+		/* prevent BL30 from using the SAR ADC while we are using it */
+		regmap_update_bits(priv->regmap, MESON_SAR_ADC_DELAY,
+				MESON_SAR_ADC_DELAY_KERNEL_BUSY,
+				MESON_SAR_ADC_DELAY_KERNEL_BUSY);
+
+		/*
+		 * wait until BL30 releases it's lock (so we can use the SAR
+		 * ADC)
+		 */
+		do {
+			udelay(1);
+			regmap_read(priv->regmap, MESON_SAR_ADC_DELAY, &val);
+		} while (val & MESON_SAR_ADC_DELAY_BL30_BUSY && timeout--);
+
+		if (timeout < 0)
+			return -ETIMEDOUT;
+	}
 
 	return 0;
 }
@@ -458,9 +464,10 @@ static void meson_sar_adc_unlock(struct iio_dev *indio_dev)
 {
 	struct meson_sar_adc_priv *priv = iio_priv(indio_dev);
 
-	/* allow BL30 to use the SAR ADC again */
-	regmap_update_bits(priv->regmap, MESON_SAR_ADC_DELAY,
-			   MESON_SAR_ADC_DELAY_KERNEL_BUSY, 0);
+	if (priv->data->has_bl30_integration)
+		/* allow BL30 to use the SAR ADC again */
+		regmap_update_bits(priv->regmap, MESON_SAR_ADC_DELAY,
+				MESON_SAR_ADC_DELAY_KERNEL_BUSY, 0);
 
 	mutex_unlock(&indio_dev->mlock);
 }
@@ -614,14 +621,16 @@ static int meson_sar_adc_init(struct iio_dev *indio_dev)
 	 */
 	meson_sar_adc_set_chan7_mux(indio_dev, CHAN7_MUX_CH7_INPUT);
 
-	/*
-	 * leave sampling delay and the input clocks as configured by BL30 to
-	 * make sure BL30 gets the values it expects when reading the
-	 * temperature sensor.
-	 */
-	regmap_read(priv->regmap, MESON_SAR_ADC_REG3, &regval);
-	if (regval & MESON_SAR_ADC_REG3_BL30_INITIALIZED)
-		return 0;
+	if (priv->data->has_bl30_integration) {
+		/*
+		 * leave sampling delay and the input clocks as configured by
+		 * BL30 to make sure BL30 gets the values it expects when
+		 * reading the temperature sensor.
+		 */
+		regmap_read(priv->regmap, MESON_SAR_ADC_REG3, &regval);
+		if (regval & MESON_SAR_ADC_REG3_BL30_INITIALIZED)
+			return 0;
+	}
 
 	meson_sar_adc_stop_sample_engine(indio_dev);
 
@@ -834,23 +843,46 @@ static const struct iio_info meson_sar_adc_iio_info = {
 	.driver_module = THIS_MODULE,
 };
 
+static struct meson_sar_adc_data meson_sar_adc_meson8_data = {
+	.has_bl30_integration = false,
+	.resolution = 10,
+	.name = "meson-meson8-saradc",
+};
+
+static struct meson_sar_adc_data meson_sar_adc_meson8b_data = {
+	.has_bl30_integration = false,
+	.resolution = 10,
+	.name = "meson-meson8b-saradc",
+};
+
 static struct meson_sar_adc_data meson_sar_adc_gxbb_data = {
+	.has_bl30_integration = true,
 	.resolution = 10,
 	.name = "meson-gxbb-saradc",
 };
 
 static struct meson_sar_adc_data meson_sar_adc_gxl_data = {
+	.has_bl30_integration = true,
 	.resolution = 12,
 	.name = "meson-gxl-saradc",
 };
 
 static struct meson_sar_adc_data meson_sar_adc_gxm_data = {
+	.has_bl30_integration = true,
 	.resolution = 12,
 	.name = "meson-gxm-saradc",
 };
 
 static const struct of_device_id meson_sar_adc_of_match[] = {
 	{
+		.compatible = "amlogic,meson8-saradc",
+		.data = &meson_sar_adc_meson8_data,
+	},
+	{
+		.compatible = "amlogic,meson8b-saradc",
+		.data = &meson_sar_adc_meson8b_data,
+	},
+	{
 		.compatible = "amlogic,meson-gxbb-saradc",
 		.data = &meson_sar_adc_gxbb_data,
 	}, {
-- 
2.12.2