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Date: Tue, 18 Aug 2015 14:32:15 +0300
From: Teodora Baluta <teodora.baluta@...el.com>
To: Peter Meerwald <pmeerw@...erw.net>
Cc: jic23@...nel.org, knaack.h@....de, lars@...afoo.de,
daniel.baluta@...el.com, linux-iio@...r.kernel.org,
linux-kernel@...r.kernel.org
Subject: Re: [PATCH v4] iio: magnetometer: add mmc34160 magnetometer driver
On Mon, Aug 17, 2015 at 09:28:41PM +0200, Peter Meerwald wrote:
> On Mon, 17 Aug 2015, Teodora Baluta wrote:
>
> > This patch adds support for the MMC34160 3-axis magnetometer driver. The
> > MMC31460 magnetometer driver uses the same register map as MMC35240 with
> > different specifications for sensitivity.
> >
> > According to Memsic specification, for the MMC31460 sensor, there is no
> > need to apply compensation to the read values. Also, the MMC34160 sensor
> > does not use the same formula as MMC35240 for transforming raw data into
> > mgauss, and the current formula is based on the input driver (mmc3416x)
> > provided by Memsic.
>
> comments below
Hi Peter,
Thanks for the review! I'll address the comments in a v5 patch. Some
answers below.
>
> > Signed-off-by: Teodora Baluta <teodora.baluta@...el.com>
> > ---
> > Changes since v3:
> > - rebased to apply correctly
> > - include bits that went missing from v2 to v3
> > - remove return variable from mmc34160_raw_to_mgauss function
> >
> > drivers/iio/magnetometer/Kconfig | 4 +-
> > drivers/iio/magnetometer/mmc35240.c | 205 ++++++++++++++++++++++++++++--------
> > 2 files changed, 162 insertions(+), 47 deletions(-)
> >
> > diff --git a/drivers/iio/magnetometer/Kconfig b/drivers/iio/magnetometer/Kconfig
> > index 868abad..df3f4cc 100644
> > --- a/drivers/iio/magnetometer/Kconfig
> > +++ b/drivers/iio/magnetometer/Kconfig
> > @@ -70,8 +70,8 @@ config MMC35240
> > select REGMAP_I2C
> > depends on I2C
> > help
> > - Say yes here to build support for the MEMSIC MMC35240 3-axis
> > - magnetic sensor.
> > + Say yes here to build support for the MEMSIC MMC35240 and MMC34160
> > + 3-axis magnetic sensors.
> >
> > To compile this driver as a module, choose M here: the module
> > will be called mmc35240.
> > diff --git a/drivers/iio/magnetometer/mmc35240.c b/drivers/iio/magnetometer/mmc35240.c
> > index 176e14a..e4fc5e4 100644
> > --- a/drivers/iio/magnetometer/mmc35240.c
> > +++ b/drivers/iio/magnetometer/mmc35240.c
> > @@ -83,6 +83,20 @@
> >
> > #define MMC35240_OTP_START_ADDR 0x1B
> >
> > +#define MMC35240_CHIP_ID 0x08
> > +#define MMC34160_CHIP_ID 0x06
> > +
> > +enum mmc35240_chipset {
> > + MMC35240,
> > + MMC34160,
> > + MMC_MAX_CHIPS
> > +};
> > +
> > +static u8 chip_ids[MMC_MAX_CHIPS] = {
>
> mmc35240_ prefix missing
>
> > + MMC35240_CHIP_ID,
> > + MMC34160_CHIP_ID,
> > +};
> > +
> > enum mmc35240_resolution {
> > MMC35240_16_BITS_SLOW = 0, /* 7.92 ms */
> > MMC35240_16_BITS_FAST, /* 4.08 ms */
> > @@ -99,27 +113,53 @@ enum mmc35240_axis {
> > static const struct {
> > int sens[3]; /* sensitivity per X, Y, Z axis */
> > int nfo; /* null field output */
> > -} mmc35240_props_table[] = {
> > - /* 16 bits, 125Hz ODR */
> > - {
> > - {1024, 1024, 1024},
> > - 32768,
> > - },
> > - /* 16 bits, 250Hz ODR */
> > - {
> > - {1024, 1024, 770},
> > - 32768,
> > - },
> > - /* 14 bits, 450Hz ODR */
> > +} mmc35240_props_table[MMC_MAX_CHIPS][4] = {
> > + /* MMC35240 */
> > {
> > - {256, 256, 193},
> > - 8192,
> > + /* 16 bits, 125Hz ODR */
> > + {
> > + {1024, 1024, 1024},
> > + 32768,
> > + },
> > + /* 16 bits, 250Hz ODR */
> > + {
> > + {1024, 1024, 770},
> > + 32768,
> > + },
> > + /* 14 bits, 450Hz ODR */
> > + {
> > + {256, 256, 193},
> > + 8192,
> > + },
> > + /* 12 bits, 800Hz ODR */
> > + {
> > + {64, 64, 48},
> > + 2048,
> > + },
> > },
> > - /* 12 bits, 800Hz ODR */
> > + /* MMC34160 */
> > {
> > - {64, 64, 48},
> > - 2048,
> > - },
> > + /* 16 bits, 125Hz ODR */
> > + {
> > + {2048, 2048, 2048},
> > + 32768,
> > + },
> > + /* 16 bits, 250Hz ODR */
> > + {
> > + {2048, 2048, 2048},
> > + 32768,
> > + },
> > + /* 14 bits, 450Hz ODR */
> > + {
> > + {512, 512, 512},
> > + 8192,
> > + },
> > + /* 12 bits, 800Hz ODR */
> > + {
> > + {128, 128, 128},
> > + 2048,
> > + },
> > + }
> > };
> >
> > struct mmc35240_data {
> > @@ -131,6 +171,7 @@ struct mmc35240_data {
> > /* OTP compensation */
> > int axis_coef[3];
> > int axis_scale[3];
> > + enum mmc35240_chipset chipset;
> > };
> >
> > static const struct {
> > @@ -206,6 +247,16 @@ static int mmc35240_hw_set(struct mmc35240_data *data, bool set)
> >
> > }
> >
> > +static inline bool mmc35240_needs_compensation(enum mmc35240_chipset chipset)
>
> maybe drop inline and let the compiler figure out
Did not take into account that the compiler can decide this for us,
though it seems pretty straight-forward it will inline it. I'll drop the
inline then.
>
> > +{
> > + switch (chipset) {
> > + case MMC35240:
> > + return true;
> > + default:
> > + return false;
> > + }
> > +}
> > +
> > static int mmc35240_init(struct mmc35240_data *data)
> > {
> > int ret, y_convert, z_convert;
> > @@ -220,6 +271,11 @@ static int mmc35240_init(struct mmc35240_data *data)
> >
> > dev_dbg(&data->client->dev, "MMC35240 chip id %x\n", reg_id);
> >
> > + if (reg_id != chip_ids[data->chipset]) {
> > + dev_err(&data->client->dev, "Invalid chip %x\n", ret);
> > + return -ENODEV;
> > + }
> > +
> > /*
> > * make sure we restore sensor characteristics, by doing
> > * a SET/RESET sequence, the axis polarity being naturally
> > @@ -241,6 +297,9 @@ static int mmc35240_init(struct mmc35240_data *data)
> > if (ret < 0)
> > return ret;
> >
> > + if (!mmc35240_needs_compensation(data->chipset))
> > + return 0;
> > +
> > ret = regmap_bulk_read(data->regmap, MMC35240_OTP_START_ADDR,
> > (u8 *)otp_data, sizeof(otp_data));
> > if (ret < 0)
> > @@ -302,9 +361,37 @@ static int mmc35240_read_measurement(struct mmc35240_data *data, __le16 buf[3])
> > 3 * sizeof(__le16));
> > }
> >
> > +static int mmc34160_raw_to_mgauss(int raw[3], int sens[3], int nfo,
> > + int index, int *val)
> > +{
> > + return (raw[index] - nfo) * 1000 / sens[index];
> > +}
> > +
> > +static int mmc35240_raw_to_mgauss(int raw[3], int sens[3], int nfo,
> > + int index, int *val)
> > +{
> > + switch (index) {
> > + case AXIS_X:
> > + *val = (raw[AXIS_X] - nfo) * 1000 / sens[AXIS_X];
> > + break;
> > + case AXIS_Y:
> > + *val = (raw[AXIS_Y] - nfo) * 1000 / sens[AXIS_Y] -
> > + (raw[AXIS_Z] - nfo) * 1000 / sens[AXIS_Z];
> > + break;
> > + case AXIS_Z:
> > + *val = (raw[AXIS_Y] - nfo) * 1000 / sens[AXIS_Y] +
> > + (raw[AXIS_Z] - nfo) * 1000 / sens[AXIS_Z];
> > + break;
> > + default:
> > + return -EINVAL;
> > + }
> > +
> > + return 0;
> > +}
> > +
> > /**
> > - * mmc35240_raw_to_mgauss - convert raw readings to milli gauss. Also apply
> > - compensation for output value.
> > + * memsic_raw_to_mgauss - convert raw readings to milli gauss. Also apply
> > + compensation for output value.
>
> why the name change?
Used the prefix for chip specific conversion - see
mmc35240_raw_to_mgauss and mmc34160_raw_to_mgauss.
I could keep the prefix for this one function and rename it to
mmc35240_raw_to_mgauss_comp (since it applies compensation as well),
remove the mmc34160_raw_to_mgauss function and put the formula directly
and keep the mmc35240_raw_to_mgauss as it is. Would that be better?
>
> > *
> > * @data: device private data
> > * @index: axis index for which we want the conversion
> > @@ -313,40 +400,42 @@ static int mmc35240_read_measurement(struct mmc35240_data *data, __le16 buf[3])
> > *
> > * Returns: 0 in case of success, -EINVAL when @index is not valid
> > */
> > -static int mmc35240_raw_to_mgauss(struct mmc35240_data *data, int index,
> > - __le16 buf[], int *val)
> > +static int memsic_raw_to_mgauss(struct mmc35240_data *data, int index,
> > + __le16 buf[], int *val)
> > {
> > int raw[3];
> > int sens[3];
> > int nfo;
> > + int ret;
> > + int id = data->chipset;
> >
> > raw[AXIS_X] = le16_to_cpu(buf[AXIS_X]);
> > raw[AXIS_Y] = le16_to_cpu(buf[AXIS_Y]);
> > raw[AXIS_Z] = le16_to_cpu(buf[AXIS_Z]);
> >
> > - sens[AXIS_X] = mmc35240_props_table[data->res].sens[AXIS_X];
> > - sens[AXIS_Y] = mmc35240_props_table[data->res].sens[AXIS_Y];
> > - sens[AXIS_Z] = mmc35240_props_table[data->res].sens[AXIS_Z];
> > + sens[AXIS_X] = mmc35240_props_table[id][data->res].sens[AXIS_X];
> > + sens[AXIS_Y] = mmc35240_props_table[id][data->res].sens[AXIS_Y];
> > + sens[AXIS_Z] = mmc35240_props_table[id][data->res].sens[AXIS_Z];
> >
> > - nfo = mmc35240_props_table[data->res].nfo;
> >
> > - switch (index) {
> > - case AXIS_X:
> > - *val = (raw[AXIS_X] - nfo) * 1000 / sens[AXIS_X];
> > - break;
> > - case AXIS_Y:
> > - *val = (raw[AXIS_Y] - nfo) * 1000 / sens[AXIS_Y] -
> > - (raw[AXIS_Z] - nfo) * 1000 / sens[AXIS_Z];
> > - break;
> > - case AXIS_Z:
> > - *val = (raw[AXIS_Y] - nfo) * 1000 / sens[AXIS_Y] +
> > - (raw[AXIS_Z] - nfo) * 1000 / sens[AXIS_Z];
> > - break;
> > + nfo = mmc35240_props_table[id][data->res].nfo;
> > +
> > + switch (id) {
> > + case MMC35240:
> > + ret = mmc35240_raw_to_mgauss(raw, sens, nfo, index, val);
> > + if (ret < 0)
> > + return ret;
> > +
> > + /* apply OTP compensation */
> > + *val = (*val) * data->axis_coef[index] /
> > + data->axis_scale[index];
> > +
> > + return 0;
> > + case MMC34160:
> > + return mmc34160_raw_to_mgauss(raw, sens, nfo, index, val);
> > default:
> > return -EINVAL;
> > }
> > - /* apply OTP compensation */
> > - *val = (*val) * data->axis_coef[index] / data->axis_scale[index];
> >
> > return 0;
> > }
> > @@ -367,7 +456,7 @@ static int mmc35240_read_raw(struct iio_dev *indio_dev,
> > mutex_unlock(&data->mutex);
> > if (ret < 0)
> > return ret;
> > - ret = mmc35240_raw_to_mgauss(data, chan->address, buf, val);
> > + ret = memsic_raw_to_mgauss(data, chan->address, buf, val);
> > if (ret < 0)
> > return ret;
> > return IIO_VAL_INT;
> > @@ -485,12 +574,27 @@ static const struct regmap_config mmc35240_regmap_config = {
> > .num_reg_defaults = ARRAY_SIZE(mmc35240_reg_defaults),
> > };
> >
> > +static const char *mmc35240_match_acpi_device(struct device *dev,
> > + enum mmc35240_chipset *chipset)
> > +{
> > + const struct acpi_device_id *id;
> > +
> > + id = acpi_match_device(dev->driver->acpi_match_table, dev);
> > + if (!id)
> > + return NULL;
> > +
> > + *chipset = (enum mmc35240_chipset)id->driver_data;
> > +
> > + return dev_name(dev);
> > +}
> > +
> > static int mmc35240_probe(struct i2c_client *client,
> > const struct i2c_device_id *id)
> > {
> > struct mmc35240_data *data;
> > struct iio_dev *indio_dev;
> > struct regmap *regmap;
> > + const char *name;
> > int ret;
> >
> > indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*data));
> > @@ -509,11 +613,20 @@ static int mmc35240_probe(struct i2c_client *client,
> > data->regmap = regmap;
> > data->res = MMC35240_16_BITS_SLOW;
> >
> > + if (id) {
> > + data->chipset = (enum mmc35240_chipset)(id->driver_data);
> > + name = id->name;
> > + } else if (ACPI_HANDLE(&client->dev)) {
> > + name = mmc35240_match_acpi_device(&client->dev,
> > + &data->chipset);
> > + } else
> > + return -ENODEV;
> > +
> > mutex_init(&data->mutex);
> >
> > indio_dev->dev.parent = &client->dev;
> > indio_dev->info = &mmc35240_info;
> > - indio_dev->name = MMC35240_DRV_NAME;
> > + indio_dev->name = name;
> > indio_dev->channels = mmc35240_channels;
> > indio_dev->num_channels = ARRAY_SIZE(mmc35240_channels);
> > indio_dev->modes = INDIO_DIRECT_MODE;
> > @@ -566,14 +679,16 @@ static const struct of_device_id mmc35240_of_match[] = {
> > MODULE_DEVICE_TABLE(of, mmc35240_of_match);
> >
> > static const struct acpi_device_id mmc35240_acpi_match[] = {
> > - {"MMC35240", 0},
> > + {"MMC35240", MMC35240},
> > + {"MMC34160", MMC34160},
> > { },
> > };
> > MODULE_DEVICE_TABLE(acpi, mmc35240_acpi_match);
> >
> > static const struct i2c_device_id mmc35240_id[] = {
> > - {"mmc35240", 0},
> > - {}
> > + {"mmc35240", MMC35240},
> > + {"mmc34160", MMC34160},
> > + { }
> > };
> > MODULE_DEVICE_TABLE(i2c, mmc35240_id);
> >
> >
>
> --
>
> Peter Meerwald
> +43-664-2444418 (mobile)
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