Re: [PATCH 2/3] iio: light: opt3001: add support for TI's opt3002 light sensor

Emil Gedenryd
2024-09-09T07:54:26Z

On Sat, 2024-09-07 at 18:35 +0100, Jonathan Cameron wrote:
> On Thu, 5 Sep 2024 12:20:46 +0200
> Emil Gedenryd <emil.gedenryd@axis.com> wrote:
>
> > TI's opt3002 light sensor shares most properties with the opt3001
> > model, with the exception of supporting a wider spectrum range.
> >
> > Add support for TI's opt3002 by extending the TI opt3001 driver.
> >
> > See https://www.ti.com/product/OPT3002 for more information.
> Make that a Datasheet tag.
> >
> Datasheet: https://www.ti.com/product/OPT3002
> > Signed-off-by: Emil Gedenryd <emil.gedenryd@axis.com>
>
> Various comments inline.
> Thanks,
>
> Jonathan

Thank you for having a look at the patch set.
I'll submit a new version that fixes the issues you highlighted
in the code and commit messages either later today or tomorrow.

Best regards,
Emil
>
> > ---
> > drivers/iio/light/Kconfig | 2 +-
> > drivers/iio/light/opt3001.c | 199 ++++++++++++++++++++++++++++++++++++--------
> > 2 files changed, 167 insertions(+), 34 deletions(-)
> >
> > diff --git a/drivers/iio/light/Kconfig b/drivers/iio/light/Kconfig
> > index b68dcc1fbaca..c35bf962dae6 100644
> > --- a/drivers/iio/light/Kconfig
> > +++ b/drivers/iio/light/Kconfig
> > @@ -461,7 +461,7 @@ config OPT3001
> > depends on I2C
> > help
> > If you say Y or M here, you get support for Texas Instruments
> > - OPT3001 Ambient Light Sensor.
> > + OPT3001 Ambient Light Sensor, OPT3002 Light-to-Digital Sensor.
> >
> > If built as a dynamically linked module, it will be called
> > opt3001.
> > diff --git a/drivers/iio/light/opt3001.c b/drivers/iio/light/opt3001.c
> > index 176e54bb48c3..e6098f88dd04 100644
> > --- a/drivers/iio/light/opt3001.c
> > +++ b/drivers/iio/light/opt3001.c
> > @@ -70,6 +70,19 @@
> > #define OPT3001_RESULT_READY_SHORT 150
> > #define OPT3001_RESULT_READY_LONG 1000
> >
> > +/* The opt3002 doesn't have a device id register, predefine value instead */
> > +#define OPT3002_DEVICE_ID_VALUE 3002
>
> Why? Just make the code not care about the value for this
> device. Add a flag to the chip info structure to say it doesn't have
> one and check that before using it.

The device id is used to log the model. Should I not log the
model for the opt3002 then or should I have the callback just return
3002? I thought it would be cleaner to have the id value as a defined
constant instead of a "magic" number in the code. Is there a preferred
way of doing it?
>
>
> > +
> > +enum chip_model {
> > + OPT3001,
> This should not be needed. See below.
>
> > + OPT3002,
> > +};
> > +
> > +struct opt300x_chip_info {
> > + enum chip_model model;
> > + enum iio_chan_type chan_type;
> > +};
> > +
> > struct opt3001 {
> > struct i2c_client *client;
> > struct device *dev;
> > @@ -79,6 +92,7 @@ struct opt3001 {
> > bool result_ready;
> > wait_queue_head_t result_ready_queue;
> > u16 result;
> > + const struct opt300x_chip_info *chip_info;
> >
> > u32 int_time;
> > u32 mode;
> > @@ -97,6 +111,16 @@ struct opt3001_scale {
> > int val2;
> > };
> >
> > +static const struct opt300x_chip_info opt3001_chip_info = {
> > + .model = OPT3001,
> Having a model in a chip_info structure is almost always a sign
> of a design that won't scale well to lots of additional devices.
>
> Get rid of that and instead add all the 'data' that you are looking
> up with that model number to this structure so it can be just
> referenced without caring which mode it is for.

Good point!
I'll move as much model-specific code as possible to the struct.

>
> > + .chan_type = IIO_LIGHT,
> > +};
> > +
> > +static const struct opt300x_chip_info opt3002_chip_info = {
> > + .model = OPT3002,
> > + .chan_type = IIO_INTENSITY,
> > +};
>
> > +
> > static int opt3001_find_scale(const struct opt3001 *opt, int val,
> > int val2, u8 *exponent)
> > {
> > int i;
> > + const struct opt3001_scale (*scale_arr)[12];
> >
> > - for (i = 0; i < ARRAY_SIZE(opt3001_scales); i++) {
> > - const struct opt3001_scale *scale = &opt3001_scales[i];
> > + switch (opt->chip_info->model) {
> > + case OPT3001:
> > + scale_arr = &opt3001_scales;
> Put them in chip_info directly, not look them up here.
>
> > + break;
> > + case OPT3002:
> > + scale_arr = &opt3002_scales;
> > + break;
> > + default:
> > + dev_err(opt->dev, "scale not configured for chip model\n");
> > + return -EINVAL;
> > + }
> >
> > + for (i = 0; i < ARRAY_SIZE(*scale_arr); i++) {
> > + const struct opt3001_scale *scale = &(*scale_arr)[i];
> > /*
> > - * Combine the integer and micro parts for comparison
> > - * purposes. Use milli lux precision to avoid 32-bit integer
> > - * overflows.
> > + * Compare the integer and micro parts to determine value scale.
> > */
> > - if ((val * 1000 + val2 / 1000) <=
> > - (scale->val * 1000 + scale->val2 / 1000)) {
> > + if (val < scale->val ||
> > + (val == scale->val && val2 <= scale->val2)) {
> > *exponent = i;
> > return 0;
> > }
> > @@ -174,11 +259,20 @@ static int opt3001_find_scale(const struct opt3001 *opt, int val,
> > static void opt3001_to_iio_ret(struct opt3001 *opt, u8 exponent,
> > u16 mantissa, int *val, int *val2)
> > {
> > - int lux;
> > + int ret;
> >
> > - lux = 10 * (mantissa << exponent);
> > - *val = lux / 1000;
> > - *val2 = (lux - (*val * 1000)) * 1000;
> > + switch (opt->chip_info->model) {
> > + case OPT3001:
> > + ret = 10 * (mantissa << exponent);
> > + *val = ret / 1000;
> > + *val2 = (ret - (*val * 1000)) * 1000;
> > + break;
> > + case OPT3002:
> > + ret = 12 * (mantissa << exponent);
> > + *val = ret / 10;
> > + *val2 = (ret - (*val * 10)) * 100000;
>
> As below - constants in the chip_info structure so this becomes
> a simple case of using them without needing to know the chip type
> in the code.
>
> > + break;
> > + }
> > }
>
> > @@ -497,7 +602,15 @@ static int opt3001_write_event_value(struct iio_dev *iio,
> > goto err;
> > }
> >
> > - mantissa = (((val * 1000) + (val2 / 1000)) / 10) >> exponent;
> > + switch (opt->chip_info->model) {
> > + case OPT3001:
> > + mantissa = (((val * 1000) + (val2 / 1000)) / 10) >> exponent;
>
> Encode the sections of this maths that is different as values in the chip
> info structure and use them directly here rather than having a switch statement.
>
> > + break;
> > + case OPT3002:
> > + mantissa = (((val * 10) + (val2 / 100000)) / 12) >> exponent;
> > + break;
> > + }
> > +
> > value = (exponent << 12) | mantissa;
> >
> > switch (dir) {
> > @@ -607,15 +720,22 @@ static int opt3001_read_id(struct opt3001 *opt)
> > manufacturer[0] = ret >> 8;
> > manufacturer[1] = ret & 0xff;
> >
> > - ret = i2c_smbus_read_word_swapped(opt->client, OPT3001_DEVICE_ID);
> > - if (ret < 0) {
> > - dev_err(opt->dev, "failed to read register %02x\n",
> > + switch (opt->chip_info->model) {
>
> Add a callback for this to the chip_info structure. That will make it
> much cleaner to add future devices.
>
> > + case OPT3001:
> > + ret = i2c_smbus_read_word_swapped(opt->client,
> > + OPT3001_DEVICE_ID);
> > + if (ret == 0) {
> > + dev_err(opt->dev, "failed to read register %02x\n",
> > OPT3001_DEVICE_ID);
> > - return ret;
> > + return ret;
> > + }
> > + device_id = ret;
> > + break;
> > + case OPT3002:
> > + device_id = OPT3002_DEVICE_ID_VALUE;
> > + break;
>
> > @@ -755,6 +877,7 @@ static int opt3001_probe(struct i2c_client *client)
> > opt = iio_priv(iio);
> > opt->client = client;
> > opt->dev = dev;
> > + opt->chip_info = device_get_match_data(&client->dev);
> >
> > mutex_init(&opt->lock);
> > init_waitqueue_head(&opt->result_ready_queue);
> > @@ -769,10 +892,18 @@ static int opt3001_probe(struct i2c_client *client)
> > return ret;
> >
> > iio->name = client->name;
> > - iio->channels = opt3001_channels;
> > - iio->num_channels = ARRAY_SIZE(opt3001_channels);
> > iio->modes = INDIO_DIRECT_MODE;
> > iio->info = &opt3001_info;
> > + switch (opt->chip_info->model) {
> > + case OPT3001:
> > + iio->channels = opt3001_channels;
> > + iio->num_channels = ARRAY_SIZE(opt3001_channels);
> Add this to the chip info structure so this can become a simple assignment
> rather than having to look up by model.
>
> > + break;
> > + case OPT3002:
> > + iio->channels = opt3002_channels;
> > + iio->num_channels = ARRAY_SIZE(opt3002_channels);
> > + break;
> > + }
> >
> > ret = devm_iio_device_register(dev, iio);
> > if (ret) {
> > @@ -826,13 +957,15 @@ static void opt3001_remove(struct i2c_client *client)
> > }
> >
> > static const struct i2c_device_id opt3001_id[] = {
> > - { "opt3001" },
> > + { "opt3001", 0 },
> > + { "opt3002", 1 },
> > { } /* Terminating Entry */
> > };
> > MODULE_DEVICE_TABLE(i2c, opt3001_id);
> >
> > static const struct of_device_id opt3001_of_match[] = {
> > - { .compatible = "ti,opt3001" },
> > + { .compatible = "ti,opt3001", .data = &opt3001_chip_info },
> > + { .compatible = "ti,opt3002", .data = &opt3002_chip_info },
> > { }
> > };
> > MODULE_DEVICE_TABLE(of, opt3001_of_match);
> >
>