Re: [PATCH 04/16] iio: adc: at91-sama5d2_adc: handle different EMR.OSR for different hw versions

From: Jonathan Cameron
Date: Sat Jun 11 2022 - 13:37:15 EST

On Thu, 9 Jun 2022 11:32:01 +0300
Claudiu Beznea <claudiu.beznea@xxxxxxxxxxxxx> wrote:

> SAMA7G5 introduces 64 and 256 oversampling rates. Due to this EMR.OSR is 3
> bits long. Change the code to reflect this. Commit prepares the code
> for the addition of 64 and 256 oversampling rates.
>
> Signed-off-by: Claudiu Beznea <claudiu.beznea@xxxxxxxxxxxxx>
> ---
> drivers/iio/adc/at91-sama5d2_adc.c | 55 ++++++++++++++++++++++--------
> 1 file changed, 40 insertions(+), 15 deletions(-)
>
> diff --git a/drivers/iio/adc/at91-sama5d2_adc.c b/drivers/iio/adc/at91-sama5d2_adc.c
> index b76328da0cb2..1ceab097335c 100644
> --- a/drivers/iio/adc/at91-sama5d2_adc.c
> +++ b/drivers/iio/adc/at91-sama5d2_adc.c
> @@ -138,8 +138,7 @@ struct at91_adc_reg_layout {
> /* Extended Mode Register */
> u16 EMR;
> /* Extended Mode Register - Oversampling rate */
> -#define AT91_SAMA5D2_EMR_OSR(V) ((V) << 16)
> -#define AT91_SAMA5D2_EMR_OSR_MASK GENMASK(17, 16)
> +#define AT91_SAMA5D2_EMR_OSR(V, M) (((V) << 16) & (M))
> #define AT91_SAMA5D2_EMR_OSR_1SAMPLES 0
> #define AT91_SAMA5D2_EMR_OSR_4SAMPLES 1
> #define AT91_SAMA5D2_EMR_OSR_16SAMPLES 2
> @@ -403,6 +402,8 @@ static const struct at91_adc_reg_layout sama7g5_layout = {
> * @max_index: highest channel index (highest index may be higher
> * than the total channel number)
> * @hw_trig_cnt: number of possible hardware triggers
> + * @osr_mask: oversampling ratio bitmask on EMR register
> + * @osr_vals: available oversampling rates
> */
> struct at91_adc_platform {
> const struct at91_adc_reg_layout *layout;
> @@ -414,6 +415,8 @@ struct at91_adc_platform {
> unsigned int max_channels;
> unsigned int max_index;
> unsigned int hw_trig_cnt;
> + unsigned int osr_mask;
> + unsigned int osr_vals;
> };
>
> /**
> @@ -612,6 +615,10 @@ static const struct at91_adc_platform sama5d2_platform = {
> .max_index = AT91_SAMA5D2_MAX_CHAN_IDX,
> #define AT91_SAMA5D2_HW_TRIG_CNT 3
> .hw_trig_cnt = AT91_SAMA5D2_HW_TRIG_CNT,
> + .osr_mask = GENMASK(17, 16),
> + .osr_vals = BIT(AT91_SAMA5D2_EMR_OSR_1SAMPLES) |
> + BIT(AT91_SAMA5D2_EMR_OSR_4SAMPLES) |
> + BIT(AT91_SAMA5D2_EMR_OSR_16SAMPLES),
> };
>
> static const struct at91_adc_platform sama7g5_platform = {
> @@ -627,6 +634,10 @@ static const struct at91_adc_platform sama7g5_platform = {
> .max_index = AT91_SAMA7G5_MAX_CHAN_IDX,
> #define AT91_SAMA7G5_HW_TRIG_CNT 3
> .hw_trig_cnt = AT91_SAMA7G5_HW_TRIG_CNT,
> + .osr_mask = GENMASK(18, 16),
> + .osr_vals = BIT(AT91_SAMA5D2_EMR_OSR_1SAMPLES) |
> + BIT(AT91_SAMA5D2_EMR_OSR_4SAMPLES) |
> + BIT(AT91_SAMA5D2_EMR_OSR_16SAMPLES),
> };
>
> static int at91_adc_chan_xlate(struct iio_dev *indio_dev, int chan)
> @@ -725,34 +736,45 @@ static void at91_adc_eoc_ena(struct at91_adc_state *st, unsigned int channel)
> at91_adc_writel(st, EOC_IER, BIT(channel));
> }
>
> -static void at91_adc_config_emr(struct at91_adc_state *st)
> +static int at91_adc_config_emr(struct at91_adc_state *st,
> + u32 oversampling_ratio)
> {
> /* configure the extended mode register */
> unsigned int emr = at91_adc_readl(st, EMR);
> + unsigned int osr_mask = st->soc_info.platform->osr_mask;
> + unsigned int osr_vals = st->soc_info.platform->osr_vals;
>
> /* select oversampling per single trigger event */
> emr |= AT91_SAMA5D2_EMR_ASTE(1);
>
> /* delete leftover content if it's the case */
> - emr &= ~AT91_SAMA5D2_EMR_OSR_MASK;
> + emr &= ~osr_mask;
>
> /* select oversampling ratio from configuration */
> - switch (st->oversampling_ratio) {
> + switch (oversampling_ratio) {
> case AT91_OSR_1SAMPLES:
> - emr |= AT91_SAMA5D2_EMR_OSR(AT91_SAMA5D2_EMR_OSR_1SAMPLES) &
> - AT91_SAMA5D2_EMR_OSR_MASK;
> + if (!(osr_vals & BIT(AT91_SAMA5D2_EMR_OSR_1SAMPLES)))
> + return -EINVAL;
> + emr |= AT91_SAMA5D2_EMR_OSR(AT91_SAMA5D2_EMR_OSR_1SAMPLES,
> + osr_mask);
> break;
> case AT91_OSR_4SAMPLES:
> - emr |= AT91_SAMA5D2_EMR_OSR(AT91_SAMA5D2_EMR_OSR_4SAMPLES) &
> - AT91_SAMA5D2_EMR_OSR_MASK;
> + if (!(osr_vals & BIT(AT91_SAMA5D2_EMR_OSR_4SAMPLES)))
> + return -EINVAL;
> + emr |= AT91_SAMA5D2_EMR_OSR(AT91_SAMA5D2_EMR_OSR_4SAMPLES,
> + osr_mask);
> break;
> case AT91_OSR_16SAMPLES:
> - emr |= AT91_SAMA5D2_EMR_OSR(AT91_SAMA5D2_EMR_OSR_16SAMPLES) &
> - AT91_SAMA5D2_EMR_OSR_MASK;
> + if (!(osr_vals & BIT(AT91_SAMA5D2_EMR_OSR_16SAMPLES)))
> + return -EINVAL;
> + emr |= AT91_SAMA5D2_EMR_OSR(AT91_SAMA5D2_EMR_OSR_16SAMPLES,
> + osr_mask);
> break;
> }
>
> at91_adc_writel(st, EMR, emr);
> +
> + return 0;
> }
>
> static int at91_adc_adjust_val_osr(struct at91_adc_state *st, int *val)
> @@ -1643,6 +1665,7 @@ static int at91_adc_write_raw(struct iio_dev *indio_dev,
> int val, int val2, long mask)
> {
> struct at91_adc_state *st = iio_priv(indio_dev);
> + int ret = 0;
>
> if (iio_buffer_enabled(indio_dev))
> return -EBUSY;
> @@ -1656,12 +1679,14 @@ static int at91_adc_write_raw(struct iio_dev *indio_dev,
> mutex_lock(&st->lock);
> if (val == st->oversampling_ratio)
> goto unlock;
> - st->oversampling_ratio = val;
> /* update ratio */
> - at91_adc_config_emr(st);
> + ret = at91_adc_config_emr(st, val);
> + if (ret)
> + goto unlock;
> + st->oversampling_ratio = val;

Good. I looked at the old ordering when reviewing earlier patch and thought
that doesn't look good :)

However, now you hae the value passed to at91_adc_config_emr() perhaps
you can drop the checking that it is a possible value from above this call
and move it to the default case on the switch statement in there?
(noticed on later patch, where that context is visible).

> unlock:
> mutex_unlock(&st->lock);
> - return 0;
> + return ret;
> case IIO_CHAN_INFO_SAMP_FREQ:
> if (val < st->soc_info.min_sample_rate ||
> val > st->soc_info.max_sample_rate)
> @@ -1834,7 +1859,7 @@ static void at91_adc_hw_init(struct iio_dev *indio_dev)
> at91_adc_setup_samp_freq(indio_dev, st->soc_info.min_sample_rate);
>
> /* configure extended mode register */
> - at91_adc_config_emr(st);
> + at91_adc_config_emr(st, st->oversampling_ratio);
> }
>
> static ssize_t at91_adc_get_fifo_state(struct device *dev,