RE: [PATCH V3 3/5] iio: accel: sca3300: modified to support multi chips

From: LI Qingwu
Date: Fri May 06 2022 - 23:49:10 EST

Hi Tomas,

Thanks a lot for your input, I will fix in the version 4.
Two explains below.

> -----Original Message-----
> From: Melin Tomas <tomas.melin@xxxxxxxxxxx>
> Sent: Saturday, May 7, 2022 4:12 AM
> To: LI Qingwu <Qing-wu.Li@xxxxxxxxxxxxxxxxxxxxxxx>; jic23@xxxxxxxxxx;
> lars@xxxxxxxxxx; robh+dt@xxxxxxxxxx; andy.shevchenko@xxxxxxxxx;
> devicetree@xxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx
> Cc: linux-iio@xxxxxxxxxxxxxxx; Rob Herring <robh@xxxxxxxxxx>
> Subject: Re: [PATCH V3 3/5] iio: accel: sca3300: modified to support multi chips
>
> This email is not from Hexagon’s Office 365 instance. Please be careful while
> clicking links, opening attachments, or replying to this email.
>
>
> Hi,
>
> Some comments below.
>
> On 04/05/2022 16:36, LI Qingwu wrote:
> > The drive support sca3300 only.
> > There are some other similar chips, for instance, SCL3300.
> > Prepare the way for multiple chips and additional channels.
> > Modify the driver to read the device id.
> > Add the tables for the corresponding id to support multiple chips.
> > Add prepares for the addition of extra channels.
> > Add prepares for handling the operation modes for multiple chips.
> >
> > Reviewed-by: Rob Herring <robh@xxxxxxxxxx>
> > Reviewed-by: Andy Shevchenko <andy.shevchenko@xxxxxxxxx>
> > Reviewed-by: Jonathan Cameron <jic23@xxxxxxxxxx>
> > Signed-off-by: LI Qingwu <Qing-wu.Li@xxxxxxxxxxxxxxxxxxxxxxx>
> > ---
> > drivers/iio/accel/sca3300.c | 180
> > ++++++++++++++++++++++++++++--------
> > 1 file changed, 141 insertions(+), 39 deletions(-)
> >
> > diff --git a/drivers/iio/accel/sca3300.c b/drivers/iio/accel/sca3300.c
> > index ff16d2cc8c70..1e0e6a2f7a63 100644
> > --- a/drivers/iio/accel/sca3300.c
> > +++ b/drivers/iio/accel/sca3300.c
> > @@ -37,7 +37,6 @@
> >
> > /* Device ID */
> > #define SCA3300_REG_WHOAMI 0x10
> > -#define SCA3300_WHOAMI_ID 0x51
> I suggest leaving this here, define another value for scl3000 if needed.
> >
> > /* Device return status and mask */
> > #define SCA3300_VALUE_RS_ERROR 0x3
> > @@ -93,15 +92,35 @@ 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_freq_tbl[] = {70, 10}; static const int
> > +sca3300_freq_modes_map[] = {0, 0, 0, 1};
> >
> > +static const int sca3300_accel_scale_tbl[][2] = {{0, 370}, {0, 741},
> > +{0, 185}}; static const int sca3300_accel_scale_modes_map[] = {0, 1,
> > +2, 2};
> Suggest keeping name of this intact, and keep name of the map variable similar.
> static const int sca3300_accel_scale[][2] = {{0, 370}, {0, 741}, {0, 185}}; static
> const int sca3300_accel_scale_map[] = {0, 1, 2, 2};
>
> That keeps it easy to remember that these are related to each other.
>
> > +
> > +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 struct iio_chan_spec *channels;
> > + const int (*accel_scale_table)[2];> + const int
> *accel_scale_modes_map;
> > + const unsigned long *scan_masks;
> > + const int *avail_modes_table;
> > + const int *freq_modes_map;
> > + const int *freq_table;> + const u8 num_accel_scales;
> > + const u8 num_avail_modes;
> > + const u8 num_channels;
> > + const u8 num_freqs;
> > + const u8 chip_id;
> > + const char *name;
> Suggest keeping related variables logically sorted in declaration together
> instead of sorting according to length.
> > +};
> > +
> > /**
> > * struct sca3300_data - device data
> > * @spi: SPI device structure
> > @@ -117,10 +136,28 @@ struct sca3300_data {
> > s16 channels[4];
> > s64 ts __aligned(sizeof(s64));
> > } scan;
> > + const struct sca3300_chip_info *chip;
> > u8 txbuf[4] ____cacheline_aligned;
> > u8 rxbuf[4];
> > };
> >
> > +static const struct sca3300_chip_info sca3300_chip_tbl[] = {
> > + { .num_accel_scales =
> ARRAY_SIZE(sca3300_accel_scale_tbl)*2,>
> + .accel_scale_modes_map = sca3300_accel_scale_modes_map,
> > + .accel_scale_table = sca3300_accel_scale_tbl,
> > + .num_channels = ARRAY_SIZE(sca3300_channels),
> > + .freq_modes_map = sca3300_freq_modes_map,
> > + .avail_modes_table = sca3300_avail_modes_map,
> > + .freq_table = sca3300_freq_tbl,
> > + .scan_masks = sca3300_scan_masks,
> > + .channels = sca3300_channels,
> > + .num_avail_modes = 4,
> > + .name = "sca3300",
> > + .chip_id = 0x51,
> > + .num_freqs = 2,
> > + },
> > +};
> > +
> > DECLARE_CRC8_TABLE(sca3300_crc_table);
> >
> > static int sca3300_transfer(struct sca3300_data *sca_data, int *val)
> > @@ -227,36 +264,80 @@ 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) {
> > + int mode;
> > +
> > + if ((index < 0) || (index >= sca_data->chip->num_avail_modes))
> > + return -EINVAL;
> > +
> > + mode = sca_data->chip->avail_modes_table[index];
> > +
> > + return sca3300_write_reg(sca_data, SCA3300_REG_MODE, mode); }
> > +
> > +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) {
> > + *index = i;
> > + break;
> > + }
> > + }
> > +
> > + return ret;
> > +}
> > +
> > 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 mode = -1;
> Suggest not setting to invalid default value, instead avoid calling function if
> values are not found.
>
> > int reg_val;
> > + int index;
> > int ret;
> > int i;
> >
> > switch (mask) {
> > case IIO_CHAN_INFO_SCALE:
> > - if (val)
> > + if (chan->type != IIO_ACCEL)
> > return -EINVAL;
> Was there some problem with if (val) here, or why changed?

The existing code check if val is 0 and val2 in the accel_scale list,
It's working because val are all 0 in the list.
Since accel_scale include both val and val2,
then it's better to check both val and val2 with the table instead of hard code 0,
the following code did the same thing.
if ((val == data->chip->accel_scale_table[index][0]) &&
(val2 == data->chip->accel_scale_table[index][1]))

> > -
> > - 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);
> > + for (i = 0; i < data->chip->num_avail_modes; i++) { 4
> > + index = data->chip->accel_scale_modes_map[i];
> > + if ((val == data->chip->accel_scale_table[index][0])
> &&
> > + (val2 == data->chip->accel_scale_table[index][1]))
> {
> > + mode = i;
> > + break;
> > + }
> > }
> > - return -EINVAL;
> > -
> > + return sca3300_set_op_mode(data, mode);
> > 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, &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;
> > + index = data->chip->accel_scale_modes_map[reg_val];
> > + for (i = 0; i < data->chip->num_avail_modes; i++) {
> > + int index_new =
> data->chip->accel_scale_modes_map[i]; 0122
> > + int index_freq = data->chip->freq_modes_map[i];
> Declare variables at top of function.
> > +
> > + if (val == data->chip->freq_table[index_freq]) {
> > + if (data->chip->accel_scale_table[index]
> ==
> > +
> > + data->chip->accel_scale_table[index_new]) {
> To be compatible with existing code, this should check that mode is 2 or 3. I
> don't see how this does that, please explain.

The purpose of existing code check mode 2 or 3 is to make sure set frequency did not impact the accel scale.
Since only for sca3300, mode 2 and 3 have same accel scale but different frequency.
In the new code,
if (data->chip->accel_scale_table[index] ==
data->chip->accel_scale_table[index_new])
also make sure the frequency did not impact the accel scale.

>
> > + mode = i;
> > + break;
> > + }
> > + }
> > + }
> > + return sca3300_set_op_mode(data, mode);
> > default:
> > return -EINVAL;
> > }
> > @@ -267,8 +348,9 @@ 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 ret;
> > int reg_val;
> > + int index;
> > + int ret;
> >
> > switch (mask) {
> > case IIO_CHAN_INFO_RAW:
> > @@ -277,17 +359,25 @@ 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, &reg_val);
> > 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_modes_map[reg_val];
> > + *val = data->chip->accel_scale_table[index][0];
> > + *val2 = data->chip->accel_scale_table[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, &reg_val);
> > if (ret)
> > return ret;
> > - *val = sca3300_lp_freq[reg_val];
> > + index = data->chip->freq_modes_map[reg_val];
> > + *val = data->chip->freq_table[index];
> > return IIO_VAL_INT;
> > default:
> > return -EINVAL;
> > @@ -331,6 +421,7 @@ 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
> > +438,22 @@ 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, "Invalid chip %x\n",
> > + value);
> Please start this with small letter, also perhaps resort to "unknown chip id %x\n"
> or so.
> > return -ENODEV;
> > }
> > +
> > + indio_dev->available_scan_masks = sca3300_chip_tbl[i].scan_masks;
> > + indio_dev->num_channels = sca3300_chip_tbl[i].num_channels;
> > + indio_dev->channels = sca3300_chip_tbl[i].channels;
> > + sca_data->chip = &sca3300_chip_tbl[i];
> > + indio_dev->name = sca3300_chip_tbl[i].name;
> > + indio_dev->modes = INDIO_DIRECT_MODE;
> > +
> I would prefer to keep the above indio_dev additions in the probe function. That
> way we keep the init function clean(er).
>
> Thanks,
> Tomas
>
> > return 0;
> > }
> >
> > @@ -384,15 +485,21 @@ 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_table;
> > + *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 +531,6 @@ 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) {