From: Naidu Tellapati <naidu.tellapati@xxxxxxxxxx>
The ADC is typically shared with remote CPUs not running Linux.
However, there is only one register to power-up/power-down. Remote CPUs
aren't able to power-up the ADC, and rely in Linux doing it instead.
This commit uses the adc-reserved-channels devicetree property to
distinguish shared usage. In this case, the ADC is powered up at
probe time.
If the ADC is used only by the CPU running Linux, power-up/down
at runtime, only when neeeded.
Signed-off-by: Naidu Tellapati <naidu.tellapati@xxxxxxxxxx>
Signed-off-by: Ezequiel Garcia <ezequiel.garcia@xxxxxxxxxx>
---
drivers/iio/adc/cc10001_adc.c | 26 +++++++++++++++++++++-----
1 file changed, 21 insertions(+), 5 deletions(-)
diff --git a/drivers/iio/adc/cc10001_adc.c b/drivers/iio/adc/cc10001_adc.c
index 10c734d..7d1b2ae 100644
--- a/drivers/iio/adc/cc10001_adc.c
+++ b/drivers/iio/adc/cc10001_adc.c
@@ -62,6 +62,7 @@ struct cc10001_adc_device {
struct regulator *reg;
u16 *buf;
+ bool shared;
struct mutex lock;
unsigned int start_delay_ns;
unsigned int eoc_delay_ns;
@@ -155,7 +156,8 @@ static irqreturn_t cc10001_adc_trigger_h(int irq, void *p)
mutex_lock(&adc_dev->lock);
- cc10001_adc_power_up(adc_dev);
+ if (!adc_dev->shared)
+ cc10001_adc_power_up(adc_dev);
/* Calculate delay step for eoc and sampled data */
delay_ns = adc_dev->eoc_delay_ns / CC10001_MAX_POLL_COUNT;
@@ -179,7 +181,8 @@ static irqreturn_t cc10001_adc_trigger_h(int irq, void *p)
}
done:
- cc10001_adc_power_down(adc_dev);
+ if (!adc_dev->shared)
+ cc10001_adc_power_down(adc_dev);
mutex_unlock(&adc_dev->lock);
@@ -198,7 +201,8 @@ static u16 cc10001_adc_read_raw_voltage(struct iio_dev *indio_dev,
unsigned int delay_ns;
u16 val;
- cc10001_adc_power_up(adc_dev);
+ if (!adc_dev->shared)
+ cc10001_adc_power_up(adc_dev);
/* Calculate delay step for eoc and sampled data */
delay_ns = adc_dev->eoc_delay_ns / CC10001_MAX_POLL_COUNT;
@@ -207,7 +211,8 @@ static u16 cc10001_adc_read_raw_voltage(struct iio_dev *indio_dev,
val = cc10001_adc_poll_done(indio_dev, chan->channel, delay_ns);
- cc10001_adc_power_down(adc_dev);
+ if (!adc_dev->shared)
+ cc10001_adc_power_down(adc_dev);
return val;
}
@@ -324,8 +329,10 @@ static int cc10001_adc_probe(struct platform_device *pdev)
adc_dev = iio_priv(indio_dev);
channel_map = GENMASK(CC10001_ADC_NUM_CHANNELS - 1, 0);
- if (!of_property_read_u32(node, "adc-reserved-channels", &ret))
+ if (!of_property_read_u32(node, "adc-reserved-channels", &ret)) {
+ adc_dev->shared = true;
channel_map &= ~ret;
+ }
adc_dev->reg = devm_regulator_get(&pdev->dev, "vref");
if (IS_ERR(adc_dev->reg))
@@ -370,6 +377,14 @@ static int cc10001_adc_probe(struct platform_device *pdev)
adc_dev->eoc_delay_ns = NSEC_PER_SEC / adc_clk_rate;
adc_dev->start_delay_ns = adc_dev->eoc_delay_ns * CC10001_WAIT_CYCLES;
+ /*
+ * There is only one register to power-up/power-down the AUX ADC.
+ * If the ADC is shared among multiple CPUs, always power it up here.
+ * If the ADC is used only by the MIPS, power-up/power-down at runtime.
+ */
+ if (adc_dev->shared)
+ cc10001_adc_power_up(adc_dev);
+
/* Setup the ADC channels available on the device */
ret = cc10001_adc_channel_init(indio_dev, channel_map);
if (ret < 0)
@@ -404,6 +419,7 @@ static int cc10001_adc_remove(struct platform_device *pdev)
struct iio_dev *indio_dev = platform_get_drvdata(pdev);
struct cc10001_adc_device *adc_dev = iio_priv(indio_dev);
+ cc10001_adc_power_down(adc_dev);
iio_device_unregister(indio_dev);
iio_triggered_buffer_cleanup(indio_dev);
clk_disable_unprepare(adc_dev->adc_clk);
--
2.3.3
--
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