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

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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>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>
This commit is contained in:
Fabrice Gasnier 2017-03-31 14:32:38 +02:00 committed by Jonathan Cameron
parent 021087309d
commit 25a85bed36
1 changed files with 49 additions and 1 deletions
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50
drivers/iio/adc/stm32-adc.c
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@ -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;