[PATCH linux dev-4.10 v2] iio: aspeed-adc: wait for initial sequence.

[Rick Altherr]

Reviewed-by: Rick Altherr <raltherr at google.com>

On Jul 14, 2017 1:12 AM, "Mykola Kostenok" <c_mykolak at mellanox.com> wrote:

> This patch enables adc engine at initialization time and waits
> for the initial sequence completion before enabling adc channels.
>
> Without this code adc channels are not functional and shows
> zeros for all connected channels.
>
> Tested on mellanox msn platform.
>
> v1 -> v2:
> Pointed by Rick Altherr:
>  - Wait init sequence code enabled by bool
> from OF match table.
>
> Signed-off-by: Mykola Kostenok <c_mykolak at mellanox.com>
> ---
>  drivers/iio/adc/aspeed_adc.c | 26 ++++++++++++++++++++++++++
>  1 file changed, 26 insertions(+)
>
> diff --git a/drivers/iio/adc/aspeed_adc.c b/drivers/iio/adc/aspeed_adc.c
> index 2283ed2..cfa7ee1 100644
> --- a/drivers/iio/adc/aspeed_adc.c
> +++ b/drivers/iio/adc/aspeed_adc.c
> @@ -22,6 +22,7 @@
>
>  #include <linux/iio/iio.h>
>  #include <linux/iio/driver.h>
> +#include <linux/iopoll.h>
>
>  #define ASPEED_RESOLUTION_BITS         10
>  #define ASPEED_CLOCKS_PER_SAMPLE       12
> @@ -38,11 +39,17 @@
>
>  #define ASPEED_ENGINE_ENABLE           BIT(0)
>
> +#define ASPEED_ADC_CTRL_INIT_RDY       BIT(8)
> +
> +#define ASPEED_ADC_INIT_POLLING_TIME   500
> +#define ASPEED_ADC_INIT_TIMEOUT                500000
> +
>  struct aspeed_adc_model_data {
>         const char *model_name;
>         unsigned int min_sampling_rate; // Hz
>         unsigned int max_sampling_rate; // Hz
>         unsigned int vref_voltage;      // mV
> +       bool wait_init_sequence;
>  };
>
>  struct aspeed_adc_data {
> @@ -210,6 +217,24 @@ static int aspeed_adc_probe(struct platform_device
> *pdev)
>                 goto scaler_error;
>         }
>
> +       model_data = of_device_get_match_data(&pdev->dev);
> +
> +       if (model_data->wait_init_sequence) {
> +               /* Enable engine in normal mode. */
> +               writel(ASPEED_OPERATION_MODE_NORMAL |
> ASPEED_ENGINE_ENABLE,
> +                      data->base + ASPEED_REG_ENGINE_CONTROL);
> +
> +               /* Wait for initial sequence complete. */
> +               ret = readl_poll_timeout(data->base +
> ASPEED_REG_ENGINE_CONTROL,
> +                                        adc_engine_control_reg_val,
> +                                        adc_engine_control_reg_val &
> +                                        ASPEED_ADC_CTRL_INIT_RDY,
> +                                        ASPEED_ADC_INIT_POLLING_TIME,
> +                                        ASPEED_ADC_INIT_TIMEOUT);
> +               if (ret)
> +                       goto scaler_error;
> +       }
> +
>         /* Start all channels in normal mode. */
>         clk_prepare_enable(data->clk_scaler->clk);
>         adc_engine_control_reg_val = GENMASK(31, 16) |
> @@ -269,6 +294,7 @@ static const struct aspeed_adc_model_data
> ast2500_model_data = {
>         .vref_voltage = 1800, // mV
>         .min_sampling_rate = 1,
>         .max_sampling_rate = 1000000,
> +       .wait_init_sequence = true,
>  };
>
>  static const struct of_device_id aspeed_adc_matches[] = {
> --
> 2.8.4
>
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.ozlabs.org/pipermail/openbmc/attachments/20170714/cc5854f6/attachment.html>