iio: at91_adc: fix missing Sample and Hold time (beca9e76) · Commits · 戴 / test

Documentation/devicetree/bindings/arm/atmel-adc.txt

+1 −0

Original line number	Diff line number	Diff line
		@@ -26,6 +26,7 @@ Optional properties:
		atmel,adc-res-names property. If not specified, the highest
		resolution will be used.
		- atmel,adc-sleep-mode: Boolean to enable sleep mode when no conversion
		- atmel,adc-sample-hold-time: Sample and Hold Time in microseconds

		Optional trigger Nodes:
		- Required properties:

drivers/iio/adc/at91_adc.c

+14 −1

Original line number	Diff line number	Diff line
		@@ -52,6 +52,7 @@ struct at91_adc_state {
		void __iomem *reg_base;
		struct at91_adc_reg_desc *registers;
		u8 startup_time;
		u8 sample_hold_time;
		bool sleep_mode;
		struct iio_trigger **trig;
		struct at91_adc_trigger *trigger_list;
		@@ -465,6 +466,9 @@ static int at91_adc_probe_dt(struct at91_adc_state *st,
		}
		st->startup_time = prop;

		prop = 0;
		of_property_read_u32(node, "atmel,adc-sample-hold-time", &prop);
		st->sample_hold_time = prop;

		if (of_property_read_u32(node, "atmel,adc-vref", &prop)) {
		dev_err(&idev->dev, "Missing adc-vref property in the DT.\n");
		@@ -578,7 +582,7 @@ static const struct iio_info at91_adc_info = {

		static int at91_adc_probe(struct platform_device *pdev)
		{
		unsigned int prsc, mstrclk, ticks, adc_clk;
		unsigned int prsc, mstrclk, ticks, adc_clk, shtim;
		int ret;
		struct iio_dev *idev;
		struct at91_adc_state *st;
		@@ -691,12 +695,21 @@ static int at91_adc_probe(struct platform_device *pdev)
		*/
		ticks = round_up((st->startup_time * adc_clk /
		1000000) - 1, 8) / 8;
		/*
		* a minimal Sample and Hold Time is necessary for the ADC to guarantee
		* the best converted final value between two channels selection
		* The formula thus is : Sample and Hold Time = (shtim + 1) / ADCClock
		*/
		shtim = round_up((st->sample_hold_time * adc_clk /
		1000000) - 1, 1);

		reg = AT91_ADC_PRESCAL_(prsc) & AT91_ADC_PRESCAL;
		reg \|= AT91_ADC_STARTUP_(ticks) & AT91_ADC_STARTUP;
		if (st->low_res)
		reg \|= AT91_ADC_LOWRES;
		if (st->sleep_mode)
		reg \|= AT91_ADC_SLEEP;
		reg \|= AT91_ADC_SHTIM_(shtim) & AT91_ADC_SHTIM;
		at91_adc_writel(st, AT91_ADC_MR, reg);

		/* Setup the ADC channels available on the board */

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