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adc: meson-saradc: add support for getting reference voltage value 

Add support for getting the 'vref-supply' regulator and register it as
ADC's reference voltage regulator, so clients can translate sampled ADC
values to the voltage.

Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
Signed-off-by: Neil Armstrong <narmstrong@baylibre.com>
This commit is contained in:
Marek Szyprowski 2021-02-18 11:33:16 +01:00 committed by Neil Armstrong
parent c0165c85c3
commit 97ab802aa3
1 changed files with 21 additions and 0 deletions
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21
drivers/adc/meson-saradc.c
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@ -18,6 +18,7 @@
#include <linux/delay.h>
#include <linux/math64.h>
#include <linux/bitfield.h>
#include <power/regulator.h>
#define MESON_SAR_ADC_REG0 0x00
#define MESON_SAR_ADC_REG0_PANEL_DETECT BIT(31)
@ -656,7 +657,10 @@ static int meson_saradc_stop(struct udevice *dev)
static int meson_saradc_probe(struct udevice *dev)
{
struct adc_uclass_plat *uc_pdata = dev_get_uclass_plat(dev);
struct meson_saradc_priv *priv = dev_get_priv(dev);
struct udevice *vref;
int vref_uv;
int ret;
ret = regmap_init_mem(dev_ofnode(dev), &priv->regmap);
@ -675,6 +679,23 @@ static int meson_saradc_probe(struct udevice *dev)
priv->active_channel = -1;
ret = device_get_supply_regulator(dev, "vref-supply", &vref);
if (ret) {
printf("can't get vref-supply: %d\n", ret);
return ret;
}
vref_uv = regulator_get_value(vref);
if (vref_uv < 0) {
printf("can't get vref-supply value: %d\n", vref_uv);
return vref_uv;
}
/* VDD supplied by common vref pin */
uc_pdata->vdd_supply = vref;
uc_pdata->vdd_microvolts = vref_uv;
uc_pdata->vss_microvolts = 0;
return 0;
}