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SubjectRe: [PATCH v2 2/2] iio: adc: stm32: add dt option to set resolution
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On 02/04/17 09:54, Jonathan Cameron wrote:
> On 31/03/17 13:32, Fabrice Gasnier wrote:
>> stm32 adc supports several resolution. Add 'assigned-resolution-bits'
>> dt optional property to set it. Default to maximum resolution in case
>> it isn't set.
>>
>> Signed-off-by: Fabrice Gasnier <fabrice.gasnier@st.com>
> The code is fine. Just waiting on review of the binding.
>
> Give me a poke if I seem to have dropped this in a week or two.
Applied to the togreg branch of iio.git and pushed out as
testing for the autobuilders to play with it.

Thanks,

Jonathan
>
> Thanks,
>
> Jonathan
>> ---
>> Changes in v2:
>> - rename property from 'st,adc-res' to 'assigned-resolution-bits', so it
>> is more common.
>> ---
>> drivers/iio/adc/stm32-adc.c | 50 ++++++++++++++++++++++++++++++++++++++++++++-
>> 1 file changed, 49 insertions(+), 1 deletion(-)
>>
>> diff --git a/drivers/iio/adc/stm32-adc.c b/drivers/iio/adc/stm32-adc.c
>> index 9b49a6ad..c28e7ff 100644
>> --- a/drivers/iio/adc/stm32-adc.c
>> +++ b/drivers/iio/adc/stm32-adc.c
>> @@ -60,6 +60,8 @@
>> #define STM32F4_EOC BIT(1)
>>
>> /* STM32F4_ADC_CR1 - bit fields */
>> +#define STM32F4_RES_SHIFT 24
>> +#define STM32F4_RES_MASK GENMASK(25, 24)
>> #define STM32F4_SCAN BIT(8)
>> #define STM32F4_EOCIE BIT(5)
>>
>> @@ -141,6 +143,7 @@ struct stm32_adc_regs {
>> * @lock: spinlock
>> * @bufi: data buffer index
>> * @num_conv: expected number of scan conversions
>> + * @res: data resolution (e.g. RES bitfield value)
>> * @trigger_polarity: external trigger polarity (e.g. exten)
>> * @dma_chan: dma channel
>> * @rx_buf: dma rx buffer cpu address
>> @@ -157,6 +160,7 @@ struct stm32_adc {
>> spinlock_t lock; /* interrupt lock */
>> unsigned int bufi;
>> unsigned int num_conv;
>> + u32 res;
>> u32 trigger_polarity;
>> struct dma_chan *dma_chan;
>> u8 *rx_buf;
>> @@ -196,6 +200,11 @@ struct stm32_adc_chan_spec {
>> { IIO_VOLTAGE, 15, "in15" },
>> };
>>
>> +static const unsigned int stm32f4_adc_resolutions[] = {
>> + /* sorted values so the index matches RES[1:0] in STM32F4_ADC_CR1 */
>> + 12, 10, 8, 6,
>> +};
>> +
>> /**
>> * stm32f4_sq - describe regular sequence registers
>> * - L: sequence len (register & bit field)
>> @@ -302,6 +311,14 @@ static void stm32_adc_conv_irq_disable(struct stm32_adc *adc)
>> stm32_adc_clr_bits(adc, STM32F4_ADC_CR1, STM32F4_EOCIE);
>> }
>>
>> +static void stm32_adc_set_res(struct stm32_adc *adc)
>> +{
>> + u32 val = stm32_adc_readl(adc, STM32F4_ADC_CR1);
>> +
>> + val = (val & ~STM32F4_RES_MASK) | (adc->res << STM32F4_RES_SHIFT);
>> + stm32_adc_writel(adc, STM32F4_ADC_CR1, val);
>> +}
>> +
>> /**
>> * stm32_adc_start_conv() - Start conversions for regular channels.
>> * @adc: stm32 adc instance
>> @@ -870,11 +887,37 @@ static irqreturn_t stm32_adc_trigger_handler(int irq, void *p)
>> {},
>> };
>>
>> +static int stm32_adc_of_get_resolution(struct iio_dev *indio_dev)
>> +{
>> + struct device_node *node = indio_dev->dev.of_node;
>> + struct stm32_adc *adc = iio_priv(indio_dev);
>> + unsigned int i;
>> + u32 res;
>> +
>> + if (of_property_read_u32(node, "assigned-resolution-bits", &res))
>> + res = stm32f4_adc_resolutions[0];
>> +
>> + for (i = 0; i < ARRAY_SIZE(stm32f4_adc_resolutions); i++)
>> + if (res == stm32f4_adc_resolutions[i])
>> + break;
>> + if (i >= ARRAY_SIZE(stm32f4_adc_resolutions)) {
>> + dev_err(&indio_dev->dev, "Bad resolution: %u bits\n", res);
>> + return -EINVAL;
>> + }
>> +
>> + dev_dbg(&indio_dev->dev, "Using %u bits resolution\n", res);
>> + adc->res = i;
>> +
>> + return 0;
>> +}
>> +
>> static void stm32_adc_chan_init_one(struct iio_dev *indio_dev,
>> struct iio_chan_spec *chan,
>> const struct stm32_adc_chan_spec *channel,
>> int scan_index)
>> {
>> + struct stm32_adc *adc = iio_priv(indio_dev);
>> +
>> chan->type = channel->type;
>> chan->channel = channel->channel;
>> chan->datasheet_name = channel->name;
>> @@ -883,7 +926,7 @@ static void stm32_adc_chan_init_one(struct iio_dev *indio_dev,
>> chan->info_mask_separate = BIT(IIO_CHAN_INFO_RAW);
>> chan->info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE);
>> chan->scan_type.sign = 'u';
>> - chan->scan_type.realbits = 12;
>> + chan->scan_type.realbits = stm32f4_adc_resolutions[adc->res];
>> chan->scan_type.storagebits = 16;
>> chan->ext_info = stm32_adc_ext_info;
>> }
>> @@ -1022,6 +1065,11 @@ static int stm32_adc_probe(struct platform_device *pdev)
>> return ret;
>> }
>>
>> + ret = stm32_adc_of_get_resolution(indio_dev);
>> + if (ret < 0)
>> + goto err_clk_disable;
>> + stm32_adc_set_res(adc);
>> +
>> ret = stm32_adc_chan_of_init(indio_dev);
>> if (ret < 0)
>> goto err_clk_disable;
>>
>
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