On 03/29/2013 02:54 PM, ludovic.desroches@xxxxxxxxx wrote:
> From: Ludovic Desroches <ludovic.desroches@xxxxxxxxx>
>
> at91 adc offers the choice between two resolutions: low and high.
> The low and high resolution values depends on adc IP version, as many IP
> properties have been exposed through device tree, these settings have also
> been added to the dt bindings.
>
> Signed-off-by: Ludovic Desroches <ludovic.desroches@xxxxxxxxx>
> Signed-off-by: Jean-Christophe PLAGNIOL-VILLARD <plagnioj@xxxxxxxxxxxx>
Applied to the togreg branch of iio.git
> ---
> .../devicetree/bindings/arm/atmel-adc.txt | 11 ++++
> drivers/iio/adc/at91_adc.c | 74 ++++++++++++++++++++--
> 2 files changed, 81 insertions(+), 4 deletions(-)
>
> diff --git a/Documentation/devicetree/bindings/arm/atmel-adc.txt b/Documentation/devicetree/bindings/arm/atmel-adc.txt
> index c63097d..fd2d69e 100644
> --- a/Documentation/devicetree/bindings/arm/atmel-adc.txt
> +++ b/Documentation/devicetree/bindings/arm/atmel-adc.txt
> @@ -14,9 +14,17 @@ Required properties:
> - atmel,adc-status-register: Offset of the Interrupt Status Register
> - atmel,adc-trigger-register: Offset of the Trigger Register
> - atmel,adc-vref: Reference voltage in millivolts for the conversions
> + - atmel,adc-res: List of resolution in bits supported by the ADC. List size
> + must be two at least.
> + - atmel,adc-res-names: Contains one identifier string for each resolution
> + in atmel,adc-res property. "lowres" and "highres"
> + identifiers are required.
>
> Optional properties:
> - atmel,adc-use-external: Boolean to enable of external triggers
> + - atmel,adc-use-res: String corresponding to an identifier from
> + atmel,adc-res-names property. If not specified, the highest
> + resolution will be used.
>
> Optional trigger Nodes:
> - Required properties:
> @@ -40,6 +48,9 @@ adc0: adc@fffb0000 {
> atmel,adc-trigger-register = <0x08>;
> atmel,adc-use-external;
> atmel,adc-vref = <3300>;
> + atmel,adc-res = <8 10>;
> + atmel,adc-res-names = "lowres", "highres";
> + atmel,adc-use-res = "lowres";
>
> trigger@0 {
> trigger-name = "external-rising";
> diff --git a/drivers/iio/adc/at91_adc.c b/drivers/iio/adc/at91_adc.c
> index 83c836b..a7ad3e7 100644
> --- a/drivers/iio/adc/at91_adc.c
> +++ b/drivers/iio/adc/at91_adc.c
> @@ -57,6 +57,8 @@ struct at91_adc_state {
> u32 trigger_number;
> bool use_external;
> u32 vref_mv;
> + u32 res; /* resolution used for convertions */
> + bool low_res; /* the resolution corresponds to the lowest one */
> wait_queue_head_t wq_data_avail;
> };
>
> @@ -138,7 +140,7 @@ static int at91_adc_channel_init(struct iio_dev *idev)
> chan->channel = bit;
> chan->scan_index = idx;
> chan->scan_type.sign = 'u';
> - chan->scan_type.realbits = 10;
> + chan->scan_type.realbits = st->res;
> chan->scan_type.storagebits = 16;
> chan->info_mask = IIO_CHAN_INFO_SCALE_SHARED_BIT |
> IIO_CHAN_INFO_RAW_SEPARATE_BIT;
> @@ -372,6 +374,59 @@ static int at91_adc_read_raw(struct iio_dev *idev,
> return -EINVAL;
> }
>
> +static int at91_adc_of_get_resolution(struct at91_adc_state *st,
> + struct platform_device *pdev)
> +{
> + struct iio_dev *idev = iio_priv_to_dev(st);
> + struct device_node *np = pdev->dev.of_node;
> + int count, i, ret = 0;
> + char *res_name, *s;
> + u32 *resolutions;
> +
> + count = of_property_count_strings(np, "atmel,adc-res-names");
> + if (count < 2) {
> + dev_err(&idev->dev, "You must specified at least two resolution names for "
> + "adc-res-names property in the DT\n");
> + return count;
> + }
> +
> + resolutions = kmalloc(count * sizeof(*resolutions), GFP_KERNEL);
> + if (!resolutions)
> + return -ENOMEM;
> +
> + if (of_property_read_u32_array(np, "atmel,adc-res", resolutions, count)) {
> + dev_err(&idev->dev, "Missing adc-res property in the DT.\n");
> + ret = -ENODEV;
> + goto ret;
> + }
> +
> + if (of_property_read_string(np, "atmel,adc-use-res", (const char **)&res_name))
> + res_name = "highres";
> +
> + for (i = 0; i < count; i++) {
> + if (of_property_read_string_index(np, "atmel,adc-res-names", i, (const char **)&s))
> + continue;
> +
> + if (strcmp(res_name, s))
> + continue;
> +
> + st->res = resolutions[i];
> + if (!strcmp(res_name, "lowres"))
> + st->low_res = true;
> + else
> + st->low_res = false;
> +
> + dev_info(&idev->dev, "Resolution used: %u bits\n", st->res);
> + goto ret;
> + }
> +
> + dev_err(&idev->dev, "There is no resolution for %s\n", res_name);
> +
> +ret:
> + kfree(resolutions);
> + return ret;
> +}
> +
> static int at91_adc_probe_dt(struct at91_adc_state *st,
> struct platform_device *pdev)
> {
> @@ -415,6 +470,10 @@ static int at91_adc_probe_dt(struct at91_adc_state *st,
> }
> st->vref_mv = prop;
>
> + ret = at91_adc_of_get_resolution(st, pdev);
> + if (ret)
> + goto error_ret;
> +
> st->registers = devm_kzalloc(&idev->dev,
> sizeof(struct at91_adc_reg_desc),
> GFP_KERNEL);
> @@ -628,9 +687,16 @@ static int at91_adc_probe(struct platform_device *pdev)
> */
> ticks = round_up((st->startup_time * adc_clk /
> 1000000) - 1, 8) / 8;
> - at91_adc_writel(st, AT91_ADC_MR,
> - (AT91_ADC_PRESCAL_(prsc) & AT91_ADC_PRESCAL) |
> - (AT91_ADC_STARTUP_(ticks) & AT91_ADC_STARTUP));
> +
> + if (st->low_res)
> + at91_adc_writel(st, AT91_ADC_MR,
> + AT91_ADC_LOWRES |
> + (AT91_ADC_PRESCAL_(prsc) & AT91_ADC_PRESCAL) |
> + (AT91_ADC_STARTUP_(ticks) & AT91_ADC_STARTUP));
> + else
> + at91_adc_writel(st, AT91_ADC_MR,
> + (AT91_ADC_PRESCAL_(prsc) & AT91_ADC_PRESCAL) |
> + (AT91_ADC_STARTUP_(ticks) & AT91_ADC_STARTUP));
>
> /* Setup the ADC channels available on the board */
> ret = at91_adc_channel_init(idev);
>
--
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