On 07/20/2013 05:27 PM, Zubair Lutfullah wrote:
> From: "Patil, Rachna" <rac...@ti.com>
>
> Previously we tried to read data form ADC even before ADC sequencer
> finished sampling. This led to wrong samples.
> We now wait on ADC status register idle bit to be set.
>
> Signed-off-by: Patil, Rachna <rac...@ti.com>
> Signed-off-by: Zubair Lutfullah <zubair.lutful...@gmail.com>
> Acked-by: Jonathan Cameron <ji...@kernel.org>
Applied this one to the fixes-togreg branch of iio.git.
I'd imagine the others will go through mfd?
> ---
> drivers/iio/adc/ti_am335x_adc.c | 30 ++++++++++++++++++++++--------
> include/linux/mfd/ti_am335x_tscadc.h | 16 ++++++++++++++++
> 2 files changed, 38 insertions(+), 8 deletions(-)
>
> diff --git a/drivers/iio/adc/ti_am335x_adc.c b/drivers/iio/adc/ti_am335x_adc.c
> index 4427e8e..f73fee1 100644
> --- a/drivers/iio/adc/ti_am335x_adc.c
> +++ b/drivers/iio/adc/ti_am335x_adc.c
> @@ -60,7 +60,6 @@ static void tiadc_step_config(struct tiadc_device *adc_dev)
> {
> unsigned int stepconfig;
> int i, steps;
> - u32 step_en;
>
> /*
> * There are 16 configurable steps and 8 analog input
> @@ -86,8 +85,7 @@ static void tiadc_step_config(struct tiadc_device *adc_dev)
> adc_dev->channel_step[i] = steps;
> steps++;
> }
> - step_en = get_adc_step_mask(adc_dev);
> - am335x_tsc_se_set(adc_dev->mfd_tscadc, step_en);
> +
> }
>
> static const char * const chan_name_ain[] = {
> @@ -142,10 +140,22 @@ static int tiadc_read_raw(struct iio_dev *indio_dev,
> int *val, int *val2, long mask)
> {
> struct tiadc_device *adc_dev = iio_priv(indio_dev);
> - int i;
> - unsigned int fifo1count, read;
> + int i, map_val;
> + unsigned int fifo1count, read, stepid;
> u32 step = UINT_MAX;
> bool found = false;
> + u32 step_en;
> + unsigned long timeout = jiffies + usecs_to_jiffies
> + (IDLE_TIMEOUT * adc_dev->channels);
> + step_en = get_adc_step_mask(adc_dev);
> + am335x_tsc_se_set(adc_dev->mfd_tscadc, step_en);
> +
> + /* Wait for ADC sequencer to complete sampling */
> + while (tiadc_readl(adc_dev, REG_ADCFSM) & SEQ_STATUS) {
> + if (time_after(jiffies, timeout))
> + return -EAGAIN;
> + }
> + map_val = chan->channel + TOTAL_CHANNELS;
>
> /*
> * When the sub-system is first enabled,
> @@ -170,12 +180,16 @@ static int tiadc_read_raw(struct iio_dev *indio_dev,
> fifo1count = tiadc_readl(adc_dev, REG_FIFO1CNT);
> for (i = 0; i < fifo1count; i++) {
> read = tiadc_readl(adc_dev, REG_FIFO1);
> - if (read >> 16 == step) {
> - *val = read & 0xfff;
> + stepid = read & FIFOREAD_CHNLID_MASK;
> + stepid = stepid >> 0x10;
> +
> + if (stepid == map_val) {
> + read = read & FIFOREAD_DATA_MASK;
> found = true;
> + *val = read;
> }
> }
> - am335x_tsc_se_update(adc_dev->mfd_tscadc);
> +
> if (found == false)
> return -EBUSY;
> return IIO_VAL_INT;
> diff --git a/include/linux/mfd/ti_am335x_tscadc.h
> b/include/linux/mfd/ti_am335x_tscadc.h
> index 8d73fe2..db1791b 100644
> --- a/include/linux/mfd/ti_am335x_tscadc.h
> +++ b/include/linux/mfd/ti_am335x_tscadc.h
> @@ -113,11 +113,27 @@
> #define CNTRLREG_8WIRE CNTRLREG_AFE_CTRL(3)
> #define CNTRLREG_TSCENB BIT(7)
>
> +/* FIFO READ Register */
> +#define FIFOREAD_DATA_MASK (0xfff << 0)
> +#define FIFOREAD_CHNLID_MASK (0xf << 16)
> +
> +/* Sequencer Status */
> +#define SEQ_STATUS BIT(5)
> +
> #define ADC_CLK 3000000
> #define MAX_CLK_DIV 7
> #define TOTAL_STEPS 16
> #define TOTAL_CHANNELS 8
>
> +/*
> +* ADC runs at 3MHz, and it takes
> +* 15 cycles to latch one data output.
> +* Hence the idle time for ADC to
> +* process one sample data would be
> +* around 5 micro seconds.
> +*/
> +#define IDLE_TIMEOUT 5 /* microsec */
> +
> #define TSCADC_CELLS 2
>
> struct ti_tscadc_dev {
>
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