On Sun, 4 Nov 2018 00:10:24 +0100
Martin Blumenstingl <martin.blumenstingl@xxxxxxxxxxxxxx> wrote:
> Channel 6 of the SAR ADC can be switched between two inputs:
> SAR_ADC_CH6 input (an actual pad on the SoC) and the signal from the
> temperature sensor inside the SoC.
>
> To get usable results from the temperature sensor we need to read the
> corresponding calibration data from the eFuse and pass it to the SAR ADC
> registers. If the temperature sensor is not calibrated (the eFuse data
> contains a bit for this) then the driver will only register the
> iio_chan_spec's for voltage measurements.
>
> (bits [3:0]) and (on Meson8b and Meson8m2) to a scratch register in the
> HHI region.
>
> This only enables the temperature sensor for the Meson8 SoC. Meson8b and
> Meson8m2 SoCs can be supported in the future as well but we first need
> a way to pass the fifth TSC (temperature sensor coefficient) bit to the
> HHI register area (apart from that the infrastructure as already
> implemented for Meson8 can be used). On the 64-bit SoCs (GXBB, GXL and
> GXM) the temperature sensor inside SAR ADC is firmware-controlled (by
> BL30, we can simply use the SCPI hwmon driver to get the chip
> temperature).
>
> To keep the devicetree interface backwards compatible we simply skip the
> temperature sensor initialization if no eFuse nvmem cell is passed via
> devicetree.
>
> The public documentation for the SAR ADC IP block does not explain how
> to use the registers to read the temperature. The logic from this patch
> is based on reading and understanding Amlogic's GPL kernel sources.
>
> Signed-off-by: Martin Blumenstingl <martin.blumenstingl@xxxxxxxxxxxxxx>
Good detailed explanation. Thanks.
Applied to the togreg branch of iio.git and pushed out as testing for
the autobuilders to play with it.
Thanks,
Jonathan
> ---
> drivers/iio/adc/meson_saradc.c | 229 +++++++++++++++++++++++++++++----
> 1 file changed, 203 insertions(+), 26 deletions(-)
>
> diff --git a/drivers/iio/adc/meson_saradc.c b/drivers/iio/adc/meson_saradc.c
> index 028ccd218f82..26011254ffbc 100644
> --- a/drivers/iio/adc/meson_saradc.c
> +++ b/drivers/iio/adc/meson_saradc.c
> @@ -18,6 +18,7 @@
> #include <linux/io.h>
> #include <linux/iio/iio.h>
> #include <linux/module.h>
> +#include <linux/nvmem-consumer.h>
> #include <linux/interrupt.h>
> #include <linux/of.h>
> #include <linux/of_irq.h>
> @@ -165,6 +166,14 @@
>
> #define MESON_SAR_ADC_MAX_FIFO_SIZE 32
> #define MESON_SAR_ADC_TIMEOUT 100 /* ms */
> +#define MESON_SAR_ADC_VOLTAGE_AND_TEMP_CHANNEL 6
> +#define MESON_SAR_ADC_TEMP_OFFSET 27
> +
> +/* temperature sensor calibration information in eFuse */
> +#define MESON_SAR_ADC_EFUSE_BYTES 4
> +#define MESON_SAR_ADC_EFUSE_BYTE3_UPPER_ADC_VAL GENMASK(6, 0)
> +#define MESON_SAR_ADC_EFUSE_BYTE3_IS_CALIBRATED BIT(7)
> +
> /* for use with IIO_VAL_INT_PLUS_MICRO */
> #define MILLION 1000000
>
> @@ -175,16 +184,25 @@
> .address = _chan, \
> .info_mask_separate = BIT(IIO_CHAN_INFO_RAW) | \
> BIT(IIO_CHAN_INFO_AVERAGE_RAW), \
> - .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE) | \
> - BIT(IIO_CHAN_INFO_CALIBBIAS) | \
> + .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE), \
> + .info_mask_shared_by_all = BIT(IIO_CHAN_INFO_CALIBBIAS) | \
> BIT(IIO_CHAN_INFO_CALIBSCALE), \
> .datasheet_name = "SAR_ADC_CH"#_chan, \
> }
>
> -/*
> - * TODO: the hardware supports IIO_TEMP for channel 6 as well which is
> - * currently not supported by this driver.
> - */
> +#define MESON_SAR_ADC_TEMP_CHAN(_chan) { \
> + .type = IIO_TEMP, \
> + .channel = _chan, \
> + .address = MESON_SAR_ADC_VOLTAGE_AND_TEMP_CHANNEL, \
> + .info_mask_separate = BIT(IIO_CHAN_INFO_RAW) | \
> + BIT(IIO_CHAN_INFO_AVERAGE_RAW), \
> + .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_OFFSET) | \
> + BIT(IIO_CHAN_INFO_SCALE), \
> + .info_mask_shared_by_all = BIT(IIO_CHAN_INFO_CALIBBIAS) | \
> + BIT(IIO_CHAN_INFO_CALIBSCALE), \
> + .datasheet_name = "TEMP_SENSOR", \
> +}
> +
> static const struct iio_chan_spec meson_sar_adc_iio_channels[] = {
> MESON_SAR_ADC_CHAN(0),
> MESON_SAR_ADC_CHAN(1),
> @@ -197,6 +215,19 @@ static const struct iio_chan_spec meson_sar_adc_iio_channels[] = {
> IIO_CHAN_SOFT_TIMESTAMP(8),
> };
>
> +static const struct iio_chan_spec meson_sar_adc_and_temp_iio_channels[] = {
> + MESON_SAR_ADC_CHAN(0),
> + MESON_SAR_ADC_CHAN(1),
> + MESON_SAR_ADC_CHAN(2),
> + MESON_SAR_ADC_CHAN(3),
> + MESON_SAR_ADC_CHAN(4),
> + MESON_SAR_ADC_CHAN(5),
> + MESON_SAR_ADC_CHAN(6),
> + MESON_SAR_ADC_CHAN(7),
> + MESON_SAR_ADC_TEMP_CHAN(8),
> + IIO_CHAN_SOFT_TIMESTAMP(9),
> +};
> +
> enum meson_sar_adc_avg_mode {
> NO_AVERAGING = 0x0,
> MEAN_AVERAGING = 0x1,
> @@ -225,6 +256,9 @@ struct meson_sar_adc_param {
> u32 bandgap_reg;
> unsigned int resolution;
> const struct regmap_config *regmap_config;
> + u8 temperature_trimming_bits;
> + unsigned int temperature_multiplier;
> + unsigned int temperature_divider;
> };
>
> struct meson_sar_adc_data {
> @@ -246,6 +280,9 @@ struct meson_sar_adc_priv {
> struct completion done;
> int calibbias;
> int calibscale;
> + bool temperature_sensor_calibrated;
> + u8 temperature_sensor_coefficient;
> + u16 temperature_sensor_adc_val;
> };
>
> static const struct regmap_config meson_sar_adc_regmap_config_gxbb = {
> @@ -389,9 +426,16 @@ static void meson_sar_adc_enable_channel(struct iio_dev *indio_dev,
> MESON_SAR_ADC_DETECT_IDLE_SW_IDLE_MUX_SEL_MASK,
> regval);
>
> - if (chan->address == 6)
> - regmap_update_bits(priv->regmap, MESON_SAR_ADC_DELTA_10,
> - MESON_SAR_ADC_DELTA_10_TEMP_SEL, 0);
> + if (chan->address == MESON_SAR_ADC_VOLTAGE_AND_TEMP_CHANNEL) {
> + if (chan->type == IIO_TEMP)
> + regval = MESON_SAR_ADC_DELTA_10_TEMP_SEL;
> + else
> + regval = 0;
> +
> + regmap_update_bits(priv->regmap,
> + MESON_SAR_ADC_DELTA_10,
> + MESON_SAR_ADC_DELTA_10_TEMP_SEL, regval);
> + }
> }
>
> static void meson_sar_adc_set_chan7_mux(struct iio_dev *indio_dev,
> @@ -506,8 +550,12 @@ static int meson_sar_adc_get_sample(struct iio_dev *indio_dev,
> enum meson_sar_adc_num_samples avg_samples,
> int *val)
> {
> + struct meson_sar_adc_priv *priv = iio_priv(indio_dev);
> int ret;
>
> + if (chan->type == IIO_TEMP && !priv->temperature_sensor_calibrated)
> + return -ENOTSUPP;
> +
> ret = meson_sar_adc_lock(indio_dev);
> if (ret)
> return ret;
> @@ -555,17 +603,31 @@ static int meson_sar_adc_iio_info_read_raw(struct iio_dev *indio_dev,
> break;
>
> case IIO_CHAN_INFO_SCALE:
> - ret = regulator_get_voltage(priv->vref);
> - if (ret < 0) {
> - dev_err(indio_dev->dev.parent,
> - "failed to get vref voltage: %d\n", ret);
> - return ret;
> + if (chan->type == IIO_VOLTAGE) {
> + ret = regulator_get_voltage(priv->vref);
> + if (ret < 0) {
> + dev_err(indio_dev->dev.parent,
> + "failed to get vref voltage: %d\n",
> + ret);
> + return ret;
> + }
> +
> + *val = ret / 1000;
> + *val2 = priv->param->resolution;
> + return IIO_VAL_FRACTIONAL_LOG2;
> + } else if (chan->type == IIO_TEMP) {
> + /* SoC specific multiplier and divider */
> + *val = priv->param->temperature_multiplier;
> + *val2 = priv->param->temperature_divider;
> +
> + /* celsius to millicelsius */
> + *val *= 1000;
> +
> + return IIO_VAL_FRACTIONAL;
> + } else {
> + return -EINVAL;
> }
>
> - *val = ret / 1000;
> - *val2 = priv->param->resolution;
> - return IIO_VAL_FRACTIONAL_LOG2;
> -
> case IIO_CHAN_INFO_CALIBBIAS:
> *val = priv->calibbias;
> return IIO_VAL_INT;
> @@ -575,6 +637,13 @@ static int meson_sar_adc_iio_info_read_raw(struct iio_dev *indio_dev,
> *val2 = priv->calibscale % MILLION;
> return IIO_VAL_INT_PLUS_MICRO;
>
> + case IIO_CHAN_INFO_OFFSET:
> + *val = DIV_ROUND_CLOSEST(MESON_SAR_ADC_TEMP_OFFSET *
> + priv->param->temperature_divider,
> + priv->param->temperature_multiplier);
> + *val -= priv->temperature_sensor_adc_val;
> + return IIO_VAL_INT;
> +
> default:
> return -EINVAL;
> }
> @@ -625,6 +694,65 @@ static int meson_sar_adc_clk_init(struct iio_dev *indio_dev,
> return 0;
> }
>
> +static int meson_sar_adc_temp_sensor_init(struct iio_dev *indio_dev)
> +{
> + struct meson_sar_adc_priv *priv = iio_priv(indio_dev);
> + u8 *buf, trimming_bits, trimming_mask, upper_adc_val;
> + struct nvmem_cell *temperature_calib;
> + size_t read_len;
> + int ret;
> +
> + temperature_calib = devm_nvmem_cell_get(&indio_dev->dev,
> + "temperature_calib");
> + if (IS_ERR(temperature_calib)) {
> + ret = PTR_ERR(temperature_calib);
> +
> + /*
> + * leave the temperature sensor disabled if no calibration data
> + * was passed via nvmem-cells.
> + */
> + if (ret == -ENODEV)
> + return 0;
> +
> + if (ret != -EPROBE_DEFER)
> + dev_err(indio_dev->dev.parent,
> + "failed to get temperature_calib cell\n");
> +
> + return ret;
> + }
> +
> + read_len = MESON_SAR_ADC_EFUSE_BYTES;
> + buf = nvmem_cell_read(temperature_calib, &read_len);
> + if (IS_ERR(buf)) {
> + dev_err(indio_dev->dev.parent,
> + "failed to read temperature_calib cell\n");
> + return PTR_ERR(buf);
> + } else if (read_len != MESON_SAR_ADC_EFUSE_BYTES) {
> + kfree(buf);
> + dev_err(indio_dev->dev.parent,
> + "invalid read size of temperature_calib cell\n");
> + return -EINVAL;
> + }
> +
> + trimming_bits = priv->param->temperature_trimming_bits;
> + trimming_mask = BIT(trimming_bits) - 1;
> +
> + priv->temperature_sensor_calibrated =
> + buf[3] & MESON_SAR_ADC_EFUSE_BYTE3_IS_CALIBRATED;
> + priv->temperature_sensor_coefficient = buf[2] & trimming_mask;
> +
> + upper_adc_val = FIELD_GET(MESON_SAR_ADC_EFUSE_BYTE3_UPPER_ADC_VAL,
> + buf[3]);
> +
> + priv->temperature_sensor_adc_val = buf[2];
> + priv->temperature_sensor_adc_val |= upper_adc_val << BITS_PER_BYTE;
> + priv->temperature_sensor_adc_val >>= trimming_bits;
> +
> + kfree(buf);
> +
> + return 0;
> +}
> +
> static int meson_sar_adc_init(struct iio_dev *indio_dev)
> {
> struct meson_sar_adc_priv *priv = iio_priv(indio_dev);
> @@ -649,10 +777,12 @@ static int meson_sar_adc_init(struct iio_dev *indio_dev)
>
> meson_sar_adc_stop_sample_engine(indio_dev);
>
> - /* update the channel 6 MUX to select the temperature sensor */
> + /*
> + * disable this bit as seems to be only relevant for Meson6 (based
> + * on the vendor driver), which we don't support at the moment.
> + */
> regmap_update_bits(priv->regmap, MESON_SAR_ADC_REG0,
> - MESON_SAR_ADC_REG0_ADC_TEMP_SEN_SEL,
> - MESON_SAR_ADC_REG0_ADC_TEMP_SEN_SEL);
> + MESON_SAR_ADC_REG0_ADC_TEMP_SEN_SEL, 0);
>
> /* disable all channels by default */
> regmap_write(priv->regmap, MESON_SAR_ADC_CHAN_LIST, 0x0);
> @@ -709,6 +839,29 @@ static int meson_sar_adc_init(struct iio_dev *indio_dev)
> regval |= MESON_SAR_ADC_AUX_SW_XP_DRIVE_SW;
> regmap_write(priv->regmap, MESON_SAR_ADC_AUX_SW, regval);
>
> + if (priv->temperature_sensor_calibrated) {
> + regmap_update_bits(priv->regmap, MESON_SAR_ADC_DELTA_10,
> + MESON_SAR_ADC_DELTA_10_TS_REVE1,
> + MESON_SAR_ADC_DELTA_10_TS_REVE1);
> + regmap_update_bits(priv->regmap, MESON_SAR_ADC_DELTA_10,
> + MESON_SAR_ADC_DELTA_10_TS_REVE0,
> + MESON_SAR_ADC_DELTA_10_TS_REVE0);
> +
> + /*
> + * set bits [3:0] of the TSC (temperature sensor coefficient)
> + * to get the correct values when reading the temperature.
> + */
> + regval = FIELD_PREP(MESON_SAR_ADC_DELTA_10_TS_C_MASK,
> + priv->temperature_sensor_coefficient);
> + regmap_update_bits(priv->regmap, MESON_SAR_ADC_DELTA_10,
> + MESON_SAR_ADC_DELTA_10_TS_C_MASK, regval);
> + } else {
> + regmap_update_bits(priv->regmap, MESON_SAR_ADC_DELTA_10,
> + MESON_SAR_ADC_DELTA_10_TS_REVE1, 0);
> + regmap_update_bits(priv->regmap, MESON_SAR_ADC_DELTA_10,
> + MESON_SAR_ADC_DELTA_10_TS_REVE0, 0);
> + }
> +
> ret = clk_set_parent(priv->adc_sel_clk, priv->clkin);
> if (ret) {
> dev_err(indio_dev->dev.parent,
> @@ -894,6 +1047,17 @@ static const struct meson_sar_adc_param meson_sar_adc_meson8_param = {
> .bandgap_reg = MESON_SAR_ADC_DELTA_10,
> .regmap_config = &meson_sar_adc_regmap_config_meson8,
> .resolution = 10,
> + .temperature_trimming_bits = 4,
> + .temperature_multiplier = 18 * 10000,
> + .temperature_divider = 1024 * 10 * 85,
> +};
> +
> +static const struct meson_sar_adc_param meson_sar_adc_meson8b_param = {
> + .has_bl30_integration = false,
> + .clock_rate = 1150000,
> + .bandgap_reg = MESON_SAR_ADC_DELTA_10,
> + .regmap_config = &meson_sar_adc_regmap_config_meson8,
> + .resolution = 10,
> };
>
> static const struct meson_sar_adc_param meson_sar_adc_gxbb_param = {
> @@ -918,12 +1082,12 @@ static const struct meson_sar_adc_data meson_sar_adc_meson8_data = {
> };
>
> static const struct meson_sar_adc_data meson_sar_adc_meson8b_data = {
> - .param = &meson_sar_adc_meson8_param,
> + .param = &meson_sar_adc_meson8b_param,
> .name = "meson-meson8b-saradc",
> };
>
> static const struct meson_sar_adc_data meson_sar_adc_meson8m2_data = {
> - .param = &meson_sar_adc_meson8_param,
> + .param = &meson_sar_adc_meson8b_param,
> .name = "meson-meson8m2-saradc",
> };
>
> @@ -1009,9 +1173,6 @@ static int meson_sar_adc_probe(struct platform_device *pdev)
> indio_dev->modes = INDIO_DIRECT_MODE;
> indio_dev->info = &meson_sar_adc_iio_info;
>
> - indio_dev->channels = meson_sar_adc_iio_channels;
> - indio_dev->num_channels = ARRAY_SIZE(meson_sar_adc_iio_channels);
> -
> res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> base = devm_ioremap_resource(&pdev->dev, res);
> if (IS_ERR(base))
> @@ -1078,6 +1239,22 @@ static int meson_sar_adc_probe(struct platform_device *pdev)
>
> priv->calibscale = MILLION;
>
> + if (priv->param->temperature_trimming_bits) {
> + ret = meson_sar_adc_temp_sensor_init(indio_dev);
> + if (ret)
> + return ret;
> + }
> +
> + if (priv->temperature_sensor_calibrated) {
> + indio_dev->channels = meson_sar_adc_and_temp_iio_channels;
> + indio_dev->num_channels =
> + ARRAY_SIZE(meson_sar_adc_and_temp_iio_channels);
> + } else {
> + indio_dev->channels = meson_sar_adc_iio_channels;
> + indio_dev->num_channels =
> + ARRAY_SIZE(meson_sar_adc_iio_channels);
> + }
> +
> ret = meson_sar_adc_init(indio_dev);
> if (ret)
> goto err;
