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Date: Mon, 17 Aug 2015 21:28:41 +0200 (CEST)
From: Peter Meerwald <pmeerw@...erw.net>
To: Teodora Baluta <teodora.baluta@...el.com>
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, 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
> 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
> +{
> + 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?
> *
> * @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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