Re: [PATCH v2 2/2] iio: adc: ti-adc128s052: Add lower resolution devices support

From: Jonathan Cameron
Date: Sun Oct 22 2023 - 12:01:04 EST

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In reply to: Sukrut Bellary: "[PATCH v2 2/2] iio: adc: ti-adc128s052: Add lower resolution devices support"
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On Sat, 21 Oct 2023 20:12:03 -0700
Sukrut Bellary <sukrut.bellary@xxxxxxxxx> wrote:

> The adcxx4s communicates with a host processor via an SPI/Microwire Bus
> interface. The device family responds with 12-bit data, of which the LSB
> bits are transmitted by the lower resolution devices as 0.
> The unavailable bits are 0 in LSB.
> Shift is calculated per resolution and used in scaling and
> raw data read.
>
> Lets reuse the driver to support the family of devices with name
> ADC<bb><c>S<sss>, where
> * bb is the resolution in number of bits (8, 10, 12)
> * c is the number of channels (1, 2, 4, 8)
> * sss is the maximum conversion speed (021 for 200 kSPS, 051 for 500 kSPS
> and 101 for 1 MSPS)
>
> Complete datasheets are available at TI's website here:
> https://www.ti.com/lit/gpn/adc<bb><c>s<sss>.pdf
>
> Tested only with ti-adc102s051 on BegalePlay SBC.
> https://www.beagleboard.org/boards/beagleplay
>
> arm64: dts: ti: k3-am625-beagleplay: Add adc102s051
> Add adc102s051 support.
> Tested on beaglePlay SBC
> https://www.beagleboard.org/boards/beagleplay
>
> Co-developed-by: Nishanth Menon <nm@xxxxxx>
> Signed-off-by: Nishanth Menon <nm@xxxxxx>
> Signed-off-by: Sukrut Bellary <sukrut.bellary@xxxxxxxxx>
> ---
> Changes in v2:
> - Arranged of_device_id and spi_device_id in numeric order.
> - Used enum to index into adc128_config.
> - Reorder adc128_config in alphabetical.
> - Include channel resolution information.
> - Shift is calculated per resolution and used in scaling and
> raw data read.
> - Link to v1: https://lore.kernel.org/all/20220701042919.18180-3-nm@xxxxxx/
> ---
> drivers/iio/adc/ti-adc128s052.c | 131 +++++++++++++++++++++++---------
> 1 file changed, 96 insertions(+), 35 deletions(-)
>
> diff --git a/drivers/iio/adc/ti-adc128s052.c b/drivers/iio/adc/ti-adc128s052.c
> index a456ea78462f..61e3181b8daf 100644
> --- a/drivers/iio/adc/ti-adc128s052.c
> +++ b/drivers/iio/adc/ti-adc128s052.c
> @@ -7,6 +7,22 @@
> * https://www.ti.com/lit/ds/symlink/adc128s052.pdf
> * https://www.ti.com/lit/ds/symlink/adc122s021.pdf
> * https://www.ti.com/lit/ds/symlink/adc124s021.pdf
> + *
> + * The adcxx4s communicates with a host processor via an SPI/Microwire Bus
> + * interface. This driver supports the whole family of devices with a name
> + * ADC<bb><c>S<sss>, where
> + * bb is the resolution in number of bits (8, 10, 12)
> + * c is the number of channels (1, 2, 4, 8)
> + * sss is the maximum conversion speed (021 for 200 kSPS, 051 for 500 kSPS
> + * and 101 for 1 MSPS)
> + *
> + * Complete datasheets are available at TI's website here:
> + * https://www.ti.com/lit/gpn/adc<bb><c>s<sss>.pdf
> + *
> + * 8, 10, and 12 bits converters send 12-bit data with
> + * unavailable bits set to 0 in LSB.
> + * Shift is calculated per resolution and used in scaling and
> + * raw data read.
> */
>
> #include <linux/err.h>
> @@ -53,7 +69,7 @@ static int adc128_adc_conversion(struct adc128 *adc, u8 channel)
> if (ret < 0)
> return ret;
>
> - return ((adc->buffer[0] << 8 | adc->buffer[1]) & 0xFFF);
> + return (adc->buffer[0] << 8 | adc->buffer[1]);
Firstly outer brackets don't add anything.
Secondly, this is an endian conversion.

return be16_to_cpu(adc->buffer);

should do the job as we know it's aligned enough for a be16.

> }
>
> static int adc128_read_raw(struct iio_dev *indio_dev,
> @@ -70,7 +86,8 @@ static int adc128_read_raw(struct iio_dev *indio_dev,
> if (ret < 0)
> return ret;
>
> - *val = ret;
> + *val = (ret >> channel->scan_type.shift) &
> + GENMASK(channel->scan_type.realbits - 1, 0);
> return IIO_VAL_INT;
>
> case IIO_CHAN_INFO_SCALE:
> @@ -80,7 +97,7 @@ static int adc128_read_raw(struct iio_dev *indio_dev,
> return ret;
>
> *val = ret / 1000;
> - *val2 = 12;
> + *val2 = channel->scan_type.realbits;
> return IIO_VAL_FRACTIONAL_LOG2;
>
> default:
> @@ -89,24 +106,34 @@ static int adc128_read_raw(struct iio_dev *indio_dev,
>
> }
>
> -#define ADC128_VOLTAGE_CHANNEL(num) \
> - { \
> - .type = IIO_VOLTAGE, \
> - .indexed = 1, \
> - .channel = (num), \
> - .info_mask_separate = BIT(IIO_CHAN_INFO_RAW), \
> - .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE) \
> +#define _ADC128_VOLTAGE_CHANNEL(num, real_bits, store_bits) \
> + { \
> + .type = IIO_VOLTAGE, \
> + .indexed = 1, \
> + .channel = (num), \
> + .info_mask_separate = BIT(IIO_CHAN_INFO_RAW), \
> + .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE), \
> + .scan_index = (num), \
> + .scan_type = { \
> + .sign = 'u', \
> + .realbits = (real_bits), \
> + .storagebits = (store_bits), \
> + .shift = (12 - real_bits), \
> + }, \
> }
>
> -static const struct iio_chan_spec adc128s052_channels[] = {
> - ADC128_VOLTAGE_CHANNEL(0),
> - ADC128_VOLTAGE_CHANNEL(1),
> - ADC128_VOLTAGE_CHANNEL(2),
> - ADC128_VOLTAGE_CHANNEL(3),
> - ADC128_VOLTAGE_CHANNEL(4),
> - ADC128_VOLTAGE_CHANNEL(5),
> - ADC128_VOLTAGE_CHANNEL(6),
> - ADC128_VOLTAGE_CHANNEL(7),
> +#define ADC082_VOLTAGE_CHANNEL(num) _ADC128_VOLTAGE_CHANNEL(num, 8, 16)
> +#define ADC102_VOLTAGE_CHANNEL(num) _ADC128_VOLTAGE_CHANNEL(num, 10, 16)
> +#define ADC128_VOLTAGE_CHANNEL(num) _ADC128_VOLTAGE_CHANNEL(num, 12, 16)
> +
> +static const struct iio_chan_spec adc082s021_channels[] = {
> + ADC082_VOLTAGE_CHANNEL(0),
> + ADC082_VOLTAGE_CHANNEL(1),
> +};
> +
> +static const struct iio_chan_spec adc102s021_channels[] = {
> + ADC102_VOLTAGE_CHANNEL(0),
> + ADC102_VOLTAGE_CHANNEL(1),
> };
>
> static const struct iio_chan_spec adc122s021_channels[] = {
> @@ -121,10 +148,32 @@ static const struct iio_chan_spec adc124s021_channels[] = {
> ADC128_VOLTAGE_CHANNEL(3),
> };
>
> +static const struct iio_chan_spec adc128s052_channels[] = {
> + ADC128_VOLTAGE_CHANNEL(0),
> + ADC128_VOLTAGE_CHANNEL(1),
> + ADC128_VOLTAGE_CHANNEL(2),
> + ADC128_VOLTAGE_CHANNEL(3),
> + ADC128_VOLTAGE_CHANNEL(4),
> + ADC128_VOLTAGE_CHANNEL(5),
> + ADC128_VOLTAGE_CHANNEL(6),
> + ADC128_VOLTAGE_CHANNEL(7),
> +};
> +
> static const struct adc128_configuration adc128_config[] = {
> - { adc128s052_channels, ARRAY_SIZE(adc128s052_channels) },
> + { adc082s021_channels, ARRAY_SIZE(adc082s021_channels) },
> + { adc102s021_channels, ARRAY_SIZE(adc102s021_channels) },
> { adc122s021_channels, ARRAY_SIZE(adc122s021_channels) },
> { adc124s021_channels, ARRAY_SIZE(adc124s021_channels) },
> + { adc128s052_channels, ARRAY_SIZE(adc128s052_channels) },
> +};
> +
> +/* Ensure match with adc128_config indices */

Make sure that is the case by using them when setting it up.

static const struct adc128_configuration adc128_config[] {
[ADC128_CONFIG_INDEX_082S] = {
adc082s021_channels, ARRAY_SIZE(..)
},
[ADC128_CONFIG_INDEX_102S] = ..
}

Or I think you can make it irrelevant by not using an array at all.
static const struct ad128_configruation adc082s021_config = {
};

etc then just use the address of the right one directly.

In this driver, I suspect that is simpler than using the array.

> +enum adc128_configuration_index {
> + ADC128_CONFIG_INDEX_082S,
> + ADC128_CONFIG_INDEX_102S,
> + ADC128_CONFIG_INDEX_122S,
> + ADC128_CONFIG_INDEX_124S,
> + ADC128_CONFIG_INDEX_128S,

> };
>
> static const struct iio_info adc128_info = {
> @@ -177,31 +226,43 @@ static int adc128_probe(struct spi_device *spi)
> }
>
> static const struct of_device_id adc128_of_match[] = {
> - { .compatible = "ti,adc128s052", .data = &adc128_config[0] },
> - { .compatible = "ti,adc122s021", .data = &adc128_config[1] },
> - { .compatible = "ti,adc122s051", .data = &adc128_config[1] },
> - { .compatible = "ti,adc122s101", .data = &adc128_config[1] },
> - { .compatible = "ti,adc124s021", .data = &adc128_config[2] },
> - { .compatible = "ti,adc124s051", .data = &adc128_config[2] },
> - { .compatible = "ti,adc124s101", .data = &adc128_config[2] },
> + { .compatible = "ti,adc082s021", .data = &adc128_config[ADC128_CONFIG_INDEX_082S] },
> + { .compatible = "ti,adc082s051", .data = &adc128_config[ADC128_CONFIG_INDEX_082S] },
> + { .compatible = "ti,adc082s101", .data = &adc128_config[ADC128_CONFIG_INDEX_082S] },
> + { .compatible = "ti,adc102s021", .data = &adc128_config[ADC128_CONFIG_INDEX_102S] },
> + { .compatible = "ti,adc102s051", .data = &adc128_config[ADC128_CONFIG_INDEX_102S] },
> + { .compatible = "ti,adc102s101", .data = &adc128_config[ADC128_CONFIG_INDEX_102S] },
> + { .compatible = "ti,adc122s021", .data = &adc128_config[ADC128_CONFIG_INDEX_122S] },
> + { .compatible = "ti,adc122s051", .data = &adc128_config[ADC128_CONFIG_INDEX_122S] },
> + { .compatible = "ti,adc122s101", .data = &adc128_config[ADC128_CONFIG_INDEX_122S] },
> + { .compatible = "ti,adc124s021", .data = &adc128_config[ADC128_CONFIG_INDEX_124S] },
> + { .compatible = "ti,adc124s051", .data = &adc128_config[ADC128_CONFIG_INDEX_124S] },
> + { .compatible = "ti,adc124s101", .data = &adc128_config[ADC128_CONFIG_INDEX_124S] },
> + { .compatible = "ti,adc128s052", .data = &adc128_config[ADC128_CONFIG_INDEX_128S] },
> { /* sentinel */ },
> };
> MODULE_DEVICE_TABLE(of, adc128_of_match);
>
> static const struct spi_device_id adc128_id[] = {
> - { "adc128s052", (kernel_ulong_t)&adc128_config[0] },
> - { "adc122s021", (kernel_ulong_t)&adc128_config[1] },
> - { "adc122s051", (kernel_ulong_t)&adc128_config[1] },
> - { "adc122s101", (kernel_ulong_t)&adc128_config[1] },
> - { "adc124s021", (kernel_ulong_t)&adc128_config[2] },
> - { "adc124s051", (kernel_ulong_t)&adc128_config[2] },
> - { "adc124s101", (kernel_ulong_t)&adc128_config[2] },
> + { "adc082s021", (kernel_ulong_t)&adc128_config[ADC128_CONFIG_INDEX_082S] },
> + { "adc082s051", (kernel_ulong_t)&adc128_config[ADC128_CONFIG_INDEX_082S] },
> + { "adc082s101", (kernel_ulong_t)&adc128_config[ADC128_CONFIG_INDEX_082S] },
> + { "adc102s021", (kernel_ulong_t)&adc128_config[ADC128_CONFIG_INDEX_102S] },
> + { "adc102s051", (kernel_ulong_t)&adc128_config[ADC128_CONFIG_INDEX_102S] },
> + { "adc102s101", (kernel_ulong_t)&adc128_config[ADC128_CONFIG_INDEX_102S] },
> + { "adc122s021", (kernel_ulong_t)&adc128_config[ADC128_CONFIG_INDEX_122S] },
> + { "adc122s051", (kernel_ulong_t)&adc128_config[ADC128_CONFIG_INDEX_122S] },
> + { "adc122s101", (kernel_ulong_t)&adc128_config[ADC128_CONFIG_INDEX_122S] },
> + { "adc124s021", (kernel_ulong_t)&adc128_config[ADC128_CONFIG_INDEX_124S] },
> + { "adc124s051", (kernel_ulong_t)&adc128_config[ADC128_CONFIG_INDEX_124S] },
> + { "adc124s101", (kernel_ulong_t)&adc128_config[ADC128_CONFIG_INDEX_124S] },
> + { "adc128s052", (kernel_ulong_t)&adc128_config[ADC128_CONFIG_INDEX_128S] },
> { }
> };
> MODULE_DEVICE_TABLE(spi, adc128_id);
>
> static const struct acpi_device_id adc128_acpi_match[] = {
> - { "AANT1280", (kernel_ulong_t)&adc128_config[2] },
> + { "AANT1280", (kernel_ulong_t)&adc128_config[ADC128_CONFIG_INDEX_124S] },
> { }
> };
> MODULE_DEVICE_TABLE(acpi, adc128_acpi_match);

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In reply to: Sukrut Bellary: "[PATCH v2 2/2] iio: adc: ti-adc128s052: Add lower resolution devices support"
Next in thread: Sukrut Bellary: "[PATCH v2 1/2] dt-bindings: iio: adc: ti,adc128s052: Add adc08c and adc10c family"
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