On 27/06/16 08:42, Vlad Dogaru wrote:
> 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.
Good point. I must be half asleep.
Linus, are we missing something? If not, I'd go without this one.
J
>
>> 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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