iio: accel: sca3300: modified to support multi chips

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@leica-geosystems.com.cn>
Reviewed-by: Tomas Melin <tomas.melin@vaisala.com>
Link: https://lore.kernel.org/r/20220529061853.3044893-4-Qing-wu.Li@leica-geosystems.com.cnSigned-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

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 +267,91 @@ 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;
+
+	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;
+
+	/*
+	 * 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 +362,8 @@ 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 +372,24 @@ 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 +433,7 @@ 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 +450,17 @@ 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 +492,21 @@ 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 +538,6 @@ 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 +545,12 @@ 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);