On Mon, 28 Oct 2024 18:14:02 +0100
Javier Carrasco <javier.carrasco.cruz@xxxxxxxxx> wrote:
> The integration time of the veml6070 depends on an external resistor
> (called Rset in the datasheet) and the value configured in the IT
> field of the command register, whose supported values are 1/2x, 1x,
> 2x and 4x.
>
> Signed-off-by: Javier Carrasco <javier.carrasco.cruz@xxxxxxxxx>
Minor thing inline about not necessarily papering over wrong
settings in DT. If someone has a genuine out of range value then we don't
want to carry on with a default. If it is a dt bug then we have no idea
what the correct value is. Either way I think printing a shouty message
and failing the probe is the way to go.
Jonathan
> ---
> drivers/iio/light/veml6070.c | 134 ++++++++++++++++++++++++++++++++++++++++---
> 1 file changed, 126 insertions(+), 8 deletions(-)
>
> diff --git a/drivers/iio/light/veml6070.c b/drivers/iio/light/veml6070.c
> index d11ae00f61f8..89b3ccb51515 100644
> --- a/drivers/iio/light/veml6070.c
> +++ b/drivers/iio/light/veml6070.c
> @@ -6,7 +6,7 @@
> *
> * IIO driver for VEML6070 (7-bit I2C slave addresses 0x38 and 0x39)
> *
> - * TODO: integration time, ACK signal
> + * TODO: ACK signal
> */
>
> #include <linux/bitfield.h>
> @@ -15,6 +15,7 @@
> #include <linux/mutex.h>
> #include <linux/err.h>
> #include <linux/delay.h>
> +#include <linux/units.h>
>
> #include <linux/iio/iio.h>
> #include <linux/iio/sysfs.h>
> @@ -29,18 +30,84 @@
> #define VEML6070_COMMAND_RSRVD BIT(1) /* reserved, set to 1 */
> #define VEML6070_COMMAND_SD BIT(0) /* shutdown mode when set */
>
> -#define VEML6070_IT_10 0x01 /* integration time 1x */
> +#define VEML6070_IT_05 0x00
> +#define VEML6070_IT_10 0x01
> +#define VEML6070_IT_20 0x02
> +#define VEML6070_IT_40 0x03
> +
> +#define VEML6070_MIN_RSET_KOHM 75
> +#define VEML6070_MIN_IT_US 15625 /* Rset = 75 kohm, IT = 1/2 */
>
> struct veml6070_data {
> struct i2c_client *client1;
> struct i2c_client *client2;
> u8 config;
> struct mutex lock;
> + u32 rset;
> + int it[4][2];
> };
>
> +static void veml6070_calc_it(struct device *dev, struct veml6070_data *data)
> +{
> + int i, tmp_it;
> +
> + data->rset = 270000;
> + device_property_read_u32(dev, "rset-ohms", &data->rset);
> +
> + if (data->rset < 75000) {
> + dev_warn(dev, "Rset too low, using minimum = 75 kohms\n");
> + data->rset = 75000;
Why are we papering over a DT issue? Are there known DT out there that hit this
we want to keep working?
If not I'd just error out on out of range values - that way they get fixed
faster!
> + }
> +
> + if (data->rset > 1200000) {
> + dev_warn(dev, "Rset too high, using maximum = 1200 kohms\n");
> + data->rset = 1200000;
> + }
> +
> + /*
> + * convert to kohm to avoid overflows and work with the same units as
> + * in the datasheet and simplify UVI operations.
> + */
> + data->rset /= KILO;
> +
> + tmp_it = VEML6070_MIN_IT_US * data->rset / VEML6070_MIN_RSET_KOHM;
> + for (i = 0; i < ARRAY_SIZE(data->it); i++) {
> + data->it[i][0] = (tmp_it << i) / MICRO;
> + data->it[i][1] = (tmp_it << i) % MICRO;
> + }
> +}
