iio: adc: at91: don't use the last converted data register

If touchscreen mode is enabled and a conversion is requested on another
channel, the result in the last converted data register can be a
touchscreen relative value. Starting a conversion involves to do a
conversion for all active channel. It starts with ADC channels and ends
with touchscreen channels. Then if ADC_LCD register is not read quickly,
its content may be a touchscreen conversion.
To remove this temporal constraint, the conversion value is taken from
the channel data register.

Signed-off-by: Ludovic Desroches <ludovic.desroches@atmel.com>
Acked-by: Alexandre Belloni <alexandre.belloni@free-electrons.com>
Acked-by: Nicolas Ferre <nicolas.ferre@atmel.com>
Cc: Stable@vger.kernel.org
Signed-off-by: Jonathan Cameron <jic23@kernel.org>

1 files changed, 7 insertions, 5 deletions

diff --git a/drivers/iio/adc/at91_adc.c b/drivers/iio/adc/at91_adc.c
index 772e869c280e..7eadaf16adc1 100644
--- a/drivers/iio/adc/at91_adc.c
+++ b/drivers/iio/adc/at91_adc.c
@@ -196,6 +196,7 @@ struct at91_adc_state {
         bool                    done;
         int                     irq;
         u16                     last_value;
+        int                     chnb;
         struct mutex            lock;
         u8                      num_channels;
         void __iomem            *reg_base;
@@ -274,7 +275,7 @@ void handle_adc_eoc_trigger(int irq, struct iio_dev *idev)
                 disable_irq_nosync(irq);
                 iio_trigger_poll(idev->trig);
         } else {
-                st->last_value = at91_adc_readl(st, AT91_ADC_LCDR);
+                st->last_value = at91_adc_readl(st, AT91_ADC_CHAN(st, st->chnb));
                 st->done = true;
                 wake_up_interruptible(&st->wq_data_avail);
         }
@@ -351,7 +352,7 @@ static irqreturn_t at91_adc_rl_interrupt(int irq, void *private)
         unsigned int reg;
 
         status &= at91_adc_readl(st, AT91_ADC_IMR);
-        if (status & st->registers->drdy_mask)
+        if (status & GENMASK(st->num_channels - 1, 0))
                 handle_adc_eoc_trigger(irq, idev);
 
         if (status & AT91RL_ADC_IER_PEN) {
@@ -418,7 +419,7 @@ static irqreturn_t at91_adc_9x5_interrupt(int irq, void *private)
                 AT91_ADC_IER_YRDY |
                 AT91_ADC_IER_PRDY;
 
-        if (status & st->registers->drdy_mask)
+        if (status & GENMASK(st->num_channels - 1, 0))
                 handle_adc_eoc_trigger(irq, idev);
 
         if (status & AT91_ADC_IER_PEN) {
@@ -689,9 +690,10 @@ static int at91_adc_read_raw(struct iio_dev *idev,
         case IIO_CHAN_INFO_RAW:
                 mutex_lock(&st->lock);
 
+                st->chnb = chan->channel;
                 at91_adc_writel(st, AT91_ADC_CHER,
                                 AT91_ADC_CH(chan->channel));
-                at91_adc_writel(st, AT91_ADC_IER, st->registers->drdy_mask);
+                at91_adc_writel(st, AT91_ADC_IER, BIT(chan->channel));
                 at91_adc_writel(st, AT91_ADC_CR, AT91_ADC_START);
 
                 ret = wait_event_interruptible_timeout(st->wq_data_avail,
@@ -708,7 +710,7 @@ static int at91_adc_read_raw(struct iio_dev *idev,
 
                 at91_adc_writel(st, AT91_ADC_CHDR,
                                 AT91_ADC_CH(chan->channel));
-                at91_adc_writel(st, AT91_ADC_IDR, st->registers->drdy_mask);
+                at91_adc_writel(st, AT91_ADC_IDR, BIT(chan->channel));
 
                 st->last_value = 0;
                 st->done = false;