On Wed, Jun 22, 2016 at 10:53:39PM +0200, Linus Walleij wrote:
> The calibration data is described as coming from an E2PROM and that
> means it does not change. Just read it once at probe time and store
> it in the device state container. Also toss the calibration data
> into the entropy pool since it is device unique.
I think my initial thought when writing this was that regmap will take
care of the caching and not hit the i2c bus each time. But I don't have
an issue with this change. Other than that, series looks good to me.
> Signed-off-by: Linus Walleij <linus.walleij@xxxxxxxxxx>
Reviewed-by: Vlad Dogaru <vlad.dogaru@xxxxxxxxx>
> ---
> ChangeLog v1->v2:
> - Remove unused dangling "ret" variable.
> ---
> drivers/iio/pressure/bmp280-core.c | 95 +++++++++++++++++++-------------------
> 1 file changed, 48 insertions(+), 47 deletions(-)
>
> diff --git a/drivers/iio/pressure/bmp280-core.c b/drivers/iio/pressure/bmp280-core.c
> index 7b2a03d6fd1d..6559455f0335 100644
> --- a/drivers/iio/pressure/bmp280-core.c
> +++ b/drivers/iio/pressure/bmp280-core.c
> @@ -29,9 +29,30 @@
> #include <linux/interrupt.h>
> #include <linux/irq.h> /* For irq_get_irq_data() */
> #include <linux/completion.h>
> +#include <linux/random.h>
>
> #include "bmp280.h"
>
> +/*
> + * These enums are used for indexing into the array of calibration
> + * coefficients for BMP180.
> + */
> +enum { AC1, AC2, AC3, AC4, AC5, AC6, B1, B2, MB, MC, MD };
> +
> +struct bmp180_calib {
> + s16 AC1;
> + s16 AC2;
> + s16 AC3;
> + u16 AC4;
> + u16 AC5;
> + u16 AC6;
> + s16 B1;
> + s16 B2;
> + s16 MB;
> + s16 MC;
> + s16 MD;
> +};
> +
> struct bmp280_data {
> struct device *dev;
> struct mutex lock;
> @@ -39,6 +60,7 @@ struct bmp280_data {
> struct completion done;
> bool use_eoc;
> const struct bmp280_chip_info *chip_info;
> + struct bmp180_calib calib;
> struct regulator *vddd;
> struct regulator *vdda;
>
> @@ -654,26 +676,6 @@ static int bmp180_read_adc_temp(struct bmp280_data *data, int *val)
> return 0;
> }
>
> -/*
> - * These enums are used for indexing into the array of calibration
> - * coefficients for BMP180.
> - */
> -enum { AC1, AC2, AC3, AC4, AC5, AC6, B1, B2, MB, MC, MD };
> -
> -struct bmp180_calib {
> - s16 AC1;
> - s16 AC2;
> - s16 AC3;
> - u16 AC4;
> - u16 AC5;
> - u16 AC6;
> - s16 B1;
> - s16 B2;
> - s16 MB;
> - s16 MC;
> - s16 MD;
> -};
> -
> static int bmp180_read_calib(struct bmp280_data *data,
> struct bmp180_calib *calib)
> {
> @@ -683,7 +685,6 @@ static int bmp180_read_calib(struct bmp280_data *data,
>
> ret = regmap_bulk_read(data->regmap, BMP180_REG_CALIB_START, buf,
> sizeof(buf));
> -
> if (ret < 0)
> return ret;
>
> @@ -693,6 +694,9 @@ static int bmp180_read_calib(struct bmp280_data *data,
> return -EIO;
> }
>
> + /* Toss the calibration data into the entropy pool */
> + add_device_randomness(buf, sizeof(buf));
> +
> calib->AC1 = be16_to_cpu(buf[AC1]);
> calib->AC2 = be16_to_cpu(buf[AC2]);
> calib->AC3 = be16_to_cpu(buf[AC3]);
> @@ -716,19 +720,11 @@ static int bmp180_read_calib(struct bmp280_data *data,
> */
> static s32 bmp180_compensate_temp(struct bmp280_data *data, s32 adc_temp)
> {
> - int ret;
> s32 x1, x2;
> - struct bmp180_calib calib;
> + struct bmp180_calib *calib = &data->calib;
>
> - ret = bmp180_read_calib(data, &calib);
> - if (ret < 0) {
> - dev_err(data->dev,
> - "failed to read calibration coefficients\n");
> - return ret;
> - }
> -
> - x1 = ((adc_temp - calib.AC6) * calib.AC5) >> 15;
> - x2 = (calib.MC << 11) / (x1 + calib.MD);
> + x1 = ((adc_temp - calib->AC6) * calib->AC5) >> 15;
> + x2 = (calib->MC << 11) / (x1 + calib->MD);
> data->t_fine = x1 + x2;
>
> return (data->t_fine + 8) >> 4;
> @@ -783,29 +779,21 @@ static int bmp180_read_adc_press(struct bmp280_data *data, int *val)
> */
> static u32 bmp180_compensate_press(struct bmp280_data *data, s32 adc_press)
> {
> - int ret;
> s32 x1, x2, x3, p;
> s32 b3, b6;
> u32 b4, b7;
> s32 oss = data->oversampling_press;
> - struct bmp180_calib calib;
> -
> - ret = bmp180_read_calib(data, &calib);
> - if (ret < 0) {
> - dev_err(data->dev,
> - "failed to read calibration coefficients\n");
> - return ret;
> - }
> + struct bmp180_calib *calib = &data->calib;
>
> b6 = data->t_fine - 4000;
> - x1 = (calib.B2 * (b6 * b6 >> 12)) >> 11;
> - x2 = calib.AC2 * b6 >> 11;
> + x1 = (calib->B2 * (b6 * b6 >> 12)) >> 11;
> + x2 = calib->AC2 * b6 >> 11;
> x3 = x1 + x2;
> - b3 = ((((s32)calib.AC1 * 4 + x3) << oss) + 2) / 4;
> - x1 = calib.AC3 * b6 >> 13;
> - x2 = (calib.B1 * ((b6 * b6) >> 12)) >> 16;
> + b3 = ((((s32)calib->AC1 * 4 + x3) << oss) + 2) / 4;
> + x1 = calib->AC3 * b6 >> 13;
> + x2 = (calib->B1 * ((b6 * b6) >> 12)) >> 16;
> x3 = (x1 + x2 + 2) >> 2;
> - b4 = calib.AC4 * (u32)(x3 + 32768) >> 15;
> + b4 = calib->AC4 * (u32)(x3 + 32768) >> 15;
> b7 = ((u32)adc_press - b3) * (50000 >> oss);
> if (b7 < 0x80000000)
> p = (b7 * 2) / b4;
> @@ -970,6 +958,19 @@ int bmp280_common_probe(struct device *dev,
> if (ret < 0)
> return ret;
>
> + /*
> + * The BMP058 and BMP180 has calibration in an E2PROM, read it out
> + * at probe time. It will not change.
> + */
> + if (chip_id == BMP180_CHIP_ID) {
> + ret = bmp180_read_calib(data, &data->calib);
> + if (ret < 0) {
> + dev_err(data->dev,
> + "failed to read calibration coefficients\n");
> + return ret;
> + }
> + }
> +
> ret = devm_iio_device_register(dev, indio_dev);
> if (ret) {
> dev_err(dev, "unable to register IIO device\n");
> --
> 2.4.11
>
> --
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