iio: adc: sc27xx: Add ADC data conversion timeout

Sometimes the ADC controller met some problems, and it will not complete
the data conversion, that will can not wake up the read process any more
to block users. So we should add one maximum conversion time to avoid
this issue.

Signed-off-by: Freeman Liu <freeman.liu@unisoc.com>
Signed-off-by: Baolin Wang <baolin.wang@linaro.org>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

diff --git a/drivers/iio/adc/sc27xx_adc.c b/drivers/iio/adc/sc27xx_adc.c
index 7940b23..f7f7a18 100644 (file)
--- a/drivers/iio/adc/sc27xx_adc.c
+++ b/drivers/iio/adc/sc27xx_adc.c
@@ -52,6 +52,9 @@
 /* Timeout (ms) for the trylock of hardware spinlocks */
 #define SC27XX_ADC_HWLOCK_TIMEOUT      5000
 
+/* Timeout (ms) for ADC data conversion according to ADC datasheet */
+#define SC27XX_ADC_RDY_TIMEOUT         100
+
 /* Maximum ADC channel number */
 #define SC27XX_ADC_CHANNEL_MAX         32
 
@@ -223,7 +226,14 @@ static int sc27xx_adc_read(struct sc27xx_adc_data *data, int channel,
        if (ret)
                goto disable_adc;
 
-       wait_for_completion(&data->completion);
+       ret = wait_for_completion_timeout(&data->completion,
+                               msecs_to_jiffies(SC27XX_ADC_RDY_TIMEOUT));
+       if (!ret) {
+               dev_err(data->dev, "read ADC data timeout\n");
+               ret = -ETIMEDOUT;
+       } else {
+               ret = 0;
+       }
 
 disable_adc:
        regmap_update_bits(data->regmap, data->base + SC27XX_ADC_CTL,