Re: [PATCH V8 3/5] iio: accel: sca3300: modified to support multi chips

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Hi,

this is looking quite good now. A few small comments below still.

On 23/05/2022 09:23, LI Qingwu wrote:
> Prepare the way for multiple chips and additional channels:
> - Modify the driver to read the device ID and load the corresponding
>   sensor information from the table to support multiple chips
> - Add prepares for the addition of extra channels
> - Prepare for handling the operation modes for multiple chips
> 
> Signed-off-by: LI Qingwu <Qing-wu.Li@xxxxxxxxxxxxxxxxxxxxxxx>
> ---
>  drivers/iio/accel/sca3300.c | 198 ++++++++++++++++++++++++++++--------
>  1 file changed, 157 insertions(+), 41 deletions(-)
> 
> diff --git a/drivers/iio/accel/sca3300.c b/drivers/iio/accel/sca3300.c
> index ff16d2cc8c70..6463d12a9ab9 100644
> --- a/drivers/iio/accel/sca3300.c
> +++ b/drivers/iio/accel/sca3300.c
> @@ -93,19 +93,40 @@ static const struct iio_chan_spec sca3300_channels[] = {
>  	IIO_CHAN_SOFT_TIMESTAMP(4),
>  };
>  
> -static const int sca3300_lp_freq[] = {70, 70, 70, 10};
> -static const int sca3300_accel_scale[][2] = {{0, 370}, {0, 741}, {0, 185}, {0, 185}};
> +static const int sca3300_lp_freq[] = {70, 10};
> +static const int sca3300_lp_freq_map[] = {0, 0, 0, 1};
>  
> +static const int sca3300_accel_scale[][2] = {{0, 370}, {0, 741}, {0, 185}};
> +static const int sca3300_accel_scale_map[] = {0, 1, 2, 2};
> +
> +static const int sca3300_avail_modes_map[] = {0, 1, 2, 3};
>  static const unsigned long sca3300_scan_masks[] = {
>  	BIT(SCA3300_ACC_X) | BIT(SCA3300_ACC_Y) | BIT(SCA3300_ACC_Z) |
>  	BIT(SCA3300_TEMP),
>  	0
>  };
>  
> +struct sca3300_chip_info {
> +	const char *name;
> +	const unsigned long *scan_masks;
> +	const struct iio_chan_spec *channels;
> +	u8 num_channels;
> +	u8 num_accel_scales;
> +	const int (*accel_scale)[2];
> +	const int *accel_scale_map;
> +	u8 num_freqs;
> +	const int *freq_table;
> +	const int *freq_map;
> +	const int *avail_modes_table;
> +	u8 num_avail_modes;
> +	u8 chip_id;
> +};
> +
>  /**
>   * struct sca3300_data - device data
>   * @spi: SPI device structure
>   * @lock: Data buffer lock
> + * @chip: Sensor chip specific information
>   * @scan: Triggered buffer. Four channel 16-bit data + 64-bit timestamp
>   * @txbuf: Transmit buffer
>   * @rxbuf: Receive buffer
> @@ -113,6 +134,7 @@ static const unsigned long sca3300_scan_masks[] = {
>  struct sca3300_data {
>  	struct spi_device *spi;
>  	struct mutex lock;
> +	const struct sca3300_chip_info *chip;
>  	struct {
>  		s16 channels[4];
>  		s64 ts __aligned(sizeof(s64));
> @@ -121,6 +143,24 @@ struct sca3300_data {
>  	u8 rxbuf[4];
>  };
>  
> +static const struct sca3300_chip_info sca3300_chip_tbl[] = {
> +	{
> +		.name = "sca3300",
> +		.scan_masks = sca3300_scan_masks,
> +		.channels = sca3300_channels,
> +		.num_channels = ARRAY_SIZE(sca3300_channels),
> +		.num_accel_scales = ARRAY_SIZE(sca3300_accel_scale)*2,
> +		.accel_scale = sca3300_accel_scale,
> +		.accel_scale_map = sca3300_accel_scale_map,
> +		.num_freqs = ARRAY_SIZE(sca3300_lp_freq),
> +		.freq_table = sca3300_lp_freq,
> +		.freq_map = sca3300_lp_freq_map,
> +		.avail_modes_table = sca3300_avail_modes_map,
> +		.num_avail_modes = 4,
> +		.chip_id = SCA3300_WHOAMI_ID,
> +	},
> +};
> +
>  DECLARE_CRC8_TABLE(sca3300_crc_table);
>  
>  static int sca3300_transfer(struct sca3300_data *sca_data, int *val)
> @@ -227,36 +267,92 @@ static int sca3300_write_reg(struct sca3300_data *sca_data, u8 reg, int val)
>  	return sca3300_error_handler(sca_data);
>  }
>  
> +static int sca3300_set_op_mode(struct sca3300_data *sca_data, int index)
> +{
> +	if ((index < 0) || (index >= sca_data->chip->num_avail_modes))
> +		return -EINVAL;
> +
> +	return sca3300_write_reg(sca_data, SCA3300_REG_MODE,
> +				 sca_data->chip->avail_modes_table[index]);
> +}
> +
> +static int sca3300_get_op_mode(struct sca3300_data *sca_data, int *index)
> +{
> +	int reg_val;
> +	int ret;
> +	int i;
> +
> +	ret = sca3300_read_reg(sca_data, SCA3300_REG_MODE, &reg_val);
> +	if (ret)
> +		return ret;
> +
> +	reg_val &= GENMASK(1, 0);

This silently assumes that mode register has always max 4 modes, yet
there is a parameter for this in chip_info (num_avail_modes).
Wondering why this masking was added, I cannot see mention about this in
datasheet that register REG_MODE would contain other bits that the
actual mode number.
Was there some specific case in mind for adding this masking?


> +	for (i = 0; i < sca_data->chip->num_avail_modes; i++) {
> +		if (sca_data->chip->avail_modes_table[i] == reg_val)
> +			break;
> +	}
> +	if (i == sca_data->chip->num_avail_modes)
> +		return -EINVAL;
> +
> +	*index = i;
> +	return 0;
> +}
> +
> +static int sca3300_set_frequency(struct sca3300_data *data, int val)
> +{
> +	const struct sca3300_chip_info *chip = data->chip;
> +	unsigned int index;
> +	int *opmode_scale;
> +	int *new_scale;
> +	unsigned int i;
> +
> +	if (sca3300_get_op_mode(data, &index))
> +		return -EINVAL;
Suggest not hiding return code from get_op_mode() here, instead use

    ret = sca3300_get_op_mode(data, &index)
    if (ret)
        return ret;

Thanks,
Tomas


> +
> +	/*
> +	 * Find a mode in which the requested sampling frequency is available
> +	 * and the scaling currently set is retained.
> +	 */
> +	opmode_scale = (int *)chip->accel_scale[chip->accel_scale_map[index]];
> +	for (i = 0; i < chip->num_avail_modes; i++) {
> +		new_scale = (int *)chip->accel_scale[chip->accel_scale_map[i]];
> +		if ((val == chip->freq_table[chip->freq_map[i]]) &&
> +		    (opmode_scale[1] == new_scale[1]) &&
> +		    (opmode_scale[0] == new_scale[0]))
> +			break;
> +	}
> +	if (i == chip->num_avail_modes)
> +		return -EINVAL;
> +
> +	return sca3300_set_op_mode(data, i);
> +}
> +
>  static int sca3300_write_raw(struct iio_dev *indio_dev,
>  			     struct iio_chan_spec const *chan,
>  			     int val, int val2, long mask)
>  {
>  	struct sca3300_data *data = iio_priv(indio_dev);
> -	int reg_val;
> -	int ret;
> +	int index;
>  	int i;
>  
>  	switch (mask) {
>  	case IIO_CHAN_INFO_SCALE:
> -		if (val)
> +		if (chan->type != IIO_ACCEL)
>  			return -EINVAL;
> -
> -		for (i = 0; i < ARRAY_SIZE(sca3300_accel_scale); i++) {
> -			if (val2 == sca3300_accel_scale[i][1])
> -				return sca3300_write_reg(data, SCA3300_REG_MODE, i);
> +		/*
> +		 * Letting scale take priority over sampling frequency.
> +		 * That makes sense given we can only ever end up increasing
> +		 * the sampling frequency which is unlikely to be a problem.
> +		 */
> +		for (i = 0; i < data->chip->num_avail_modes; i++) {
> +			index = data->chip->accel_scale_map[i];
> +			if ((val  == data->chip->accel_scale[index][0]) &&
> +			    (val2 == data->chip->accel_scale[index][1]))
> +				return sca3300_set_op_mode(data, i);
>  		}
>  		return -EINVAL;
> -
>  	case IIO_CHAN_INFO_LOW_PASS_FILTER_3DB_FREQUENCY:
> -		ret = sca3300_read_reg(data, SCA3300_REG_MODE, &reg_val);
> -		if (ret)
> -			return ret;
> -		/* freq. change is possible only for mode 3 and 4 */
> -		if (reg_val == 2 && val == sca3300_lp_freq[3])
> -			return sca3300_write_reg(data, SCA3300_REG_MODE, 3);
> -		if (reg_val == 3 && val == sca3300_lp_freq[2])
> -			return sca3300_write_reg(data, SCA3300_REG_MODE, 2);
> -		return -EINVAL;
> +		return sca3300_set_frequency(data, val);
>  	default:
>  		return -EINVAL;
>  	}
> @@ -267,8 +363,8 @@ static int sca3300_read_raw(struct iio_dev *indio_dev,
>  			    int *val, int *val2, long mask)
>  {
>  	struct sca3300_data *data = iio_priv(indio_dev);
> +	int index;
>  	int ret;
> -	int reg_val;
>  
>  	switch (mask) {
>  	case IIO_CHAN_INFO_RAW:
> @@ -277,17 +373,24 @@ static int sca3300_read_raw(struct iio_dev *indio_dev,
>  			return ret;
>  		return IIO_VAL_INT;
>  	case IIO_CHAN_INFO_SCALE:
> -		ret = sca3300_read_reg(data, SCA3300_REG_MODE, &reg_val);
> +		ret = sca3300_get_op_mode(data, &index);
>  		if (ret)
>  			return ret;
> -		*val = 0;
> -		*val2 = sca3300_accel_scale[reg_val][1];
> -		return IIO_VAL_INT_PLUS_MICRO;
> +		switch (chan->type) {
> +		case IIO_ACCEL:
> +			index = data->chip->accel_scale_map[index];
> +			*val  = data->chip->accel_scale[index][0];
> +			*val2 = data->chip->accel_scale[index][1];
> +			return IIO_VAL_INT_PLUS_MICRO;
> +		default:
> +			return -EINVAL;
> +		}
>  	case IIO_CHAN_INFO_LOW_PASS_FILTER_3DB_FREQUENCY:
> -		ret = sca3300_read_reg(data, SCA3300_REG_MODE, &reg_val);
> +		ret = sca3300_get_op_mode(data, &index);
>  		if (ret)
>  			return ret;
> -		*val = sca3300_lp_freq[reg_val];
> +		index = data->chip->freq_map[index];
> +		*val = data->chip->freq_table[index];
>  		return IIO_VAL_INT;
>  	default:
>  		return -EINVAL;
> @@ -331,6 +434,7 @@ static int sca3300_init(struct sca3300_data *sca_data,
>  {
>  	int value = 0;
>  	int ret;
> +	int i;
>  
>  	ret = sca3300_write_reg(sca_data, SCA3300_REG_MODE,
>  				SCA3300_MODE_SW_RESET);
> @@ -347,12 +451,17 @@ static int sca3300_init(struct sca3300_data *sca_data,
>  	if (ret)
>  		return ret;
>  
> -	if (value != SCA3300_WHOAMI_ID) {
> -		dev_err(&sca_data->spi->dev,
> -			"device id not expected value, %d != %u\n",
> -			value, SCA3300_WHOAMI_ID);
> +	for (i = 0; i < ARRAY_SIZE(sca3300_chip_tbl); i++) {
> +		if (sca3300_chip_tbl[i].chip_id == value)
> +			break;
> +	}
> +	if (i == ARRAY_SIZE(sca3300_chip_tbl)) {
> +		dev_err(&sca_data->spi->dev, "unknown chip id %x\n", value);
>  		return -ENODEV;
>  	}
> +
> +	sca_data->chip = &sca3300_chip_tbl[i];
> +
>  	return 0;
>  }
>  
> @@ -384,15 +493,21 @@ static int sca3300_read_avail(struct iio_dev *indio_dev,
>  			      const int **vals, int *type, int *length,
>  			      long mask)
>  {
> +	struct sca3300_data *data = iio_priv(indio_dev);
>  	switch (mask) {
>  	case IIO_CHAN_INFO_SCALE:
> -		*vals = (const int *)sca3300_accel_scale;
> -		*length = ARRAY_SIZE(sca3300_accel_scale) * 2 - 2;
> -		*type = IIO_VAL_INT_PLUS_MICRO;
> -		return IIO_AVAIL_LIST;
> +		switch (chan->type) {
> +		case IIO_ACCEL:
> +			*vals = (const int *)data->chip->accel_scale;
> +			*length = data->chip->num_accel_scales;
> +			*type = IIO_VAL_INT_PLUS_MICRO;
> +			return IIO_AVAIL_LIST;
> +		default:
> +			return -EINVAL;
> +		}
>  	case IIO_CHAN_INFO_LOW_PASS_FILTER_3DB_FREQUENCY:
> -		*vals = &sca3300_lp_freq[2];
> -		*length = 2;
> +		*vals = (const int *)data->chip->freq_table;
> +		*length = data->chip->num_freqs;
>  		*type = IIO_VAL_INT;
>  		return IIO_AVAIL_LIST;
>  	default:
> @@ -424,11 +539,6 @@ static int sca3300_probe(struct spi_device *spi)
>  	crc8_populate_msb(sca3300_crc_table, SCA3300_CRC8_POLYNOMIAL);
>  
>  	indio_dev->info = &sca3300_info;
> -	indio_dev->name = SCA3300_ALIAS;
> -	indio_dev->modes = INDIO_DIRECT_MODE;
> -	indio_dev->channels = sca3300_channels;
> -	indio_dev->num_channels = ARRAY_SIZE(sca3300_channels);
> -	indio_dev->available_scan_masks = sca3300_scan_masks;
>  
>  	ret = sca3300_init(sca_data, indio_dev);
>  	if (ret) {
> @@ -436,6 +546,12 @@ static int sca3300_probe(struct spi_device *spi)
>  		return ret;
>  	}
>  
> +	indio_dev->name = sca_data->chip->name;
> +	indio_dev->modes = INDIO_DIRECT_MODE;
> +	indio_dev->channels = sca_data->chip->channels;
> +	indio_dev->num_channels = sca_data->chip->num_channels;
> +	indio_dev->available_scan_masks = sca_data->chip->scan_masks;
> +
>  	ret = devm_iio_triggered_buffer_setup(&spi->dev, indio_dev,
>  					      iio_pollfunc_store_time,
>  					      sca3300_trigger_handler, NULL);



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