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Commit 25a85bed authored by Fabrice Gasnier's avatar Fabrice Gasnier Committed by Jonathan Cameron
Browse files

iio: adc: stm32: add dt option to set resolution 



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: default avatarFabrice Gasnier <fabrice.gasnier@st.com>
Signed-off-by: default avatarJonathan Cameron <jic23@kernel.org>
parent 02108730

drivers/iio/adc/stm32-adc.c

+49 −1
Original line number Diff line number Diff line
@@ -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 @@ static const struct stm32_adc_chan_spec stm32f4_adc123_channels[] = { 
	{ 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 const struct iio_chan_spec_ext_info stm32_adc_ext_info[] = { 
	{},

};



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;