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SubjectRe: [PATCH v2 2/2] iio: adc: stm32: add dt option to set resolution
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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.

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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