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>

diff --git a/drivers/iio/adc/at91_adc.c b/drivers/iio/adc/at91_adc.c
index 772e869c280ed2c7a275ba3516fa66b997d00379..7eadaf16adc1eb97ed2e49562558294012db2ad0 100644 (file)
--- 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;