Date:	Sun, 05 Jul 2015 13:59:39 +0100
From:	Jonathan Cameron <jic23@...nel.org>
To:	Teodora Baluta <teodora.baluta@...el.com>
CC:	knaack.h@....de, lars@...afoo.de, pmeerw@...erw.net,
	daniel.baluta@...el.com, dan.carpenter@...cle.com,
	linux-iio@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/2] iio: magnetometer: add mmc34160 magnetometer driver

On 29/06/15 13:44, 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.
> 
> Signed-off-by: Teodora Baluta <teodora.baluta@...el.com>
Mostly looks fine.  Couple of little bits inline.  Also might want
to hold this until the fix in the previous patch has worked it's way through
to the togreg branch of iio.git (few weeks typically).

Jonathan
> ---
> This depends on the following patch https://lkml.org/lkml/2015/6/15/311
> ---
>  drivers/iio/magnetometer/Kconfig    |   5 +-
>  drivers/iio/magnetometer/mmc35240.c | 228 ++++++++++++++++++++++++++++--------
>  2 files changed, 181 insertions(+), 52 deletions(-)
> 
> diff --git a/drivers/iio/magnetometer/Kconfig b/drivers/iio/magnetometer/Kconfig
> index dcadfc4..baf59d9 100644
> --- a/drivers/iio/magnetometer/Kconfig
> +++ b/drivers/iio/magnetometer/Kconfig
> @@ -52,8 +52,9 @@ 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 3-axis magnetic
> +	  sensor. This driver also adds support for the MEMSIC MMC34160 3-axis magnetic
> +	  sensor.
This way of describing the supported parts is going to get nasty if we have any more!

Say yes here to build support for the MEMSIC MMC35240 and MMC34160 3-axis...

>  
>  	  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 36a4b53..c1cf01e 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_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)
>  				  coil_bit);
>  }
>  
> +static inline bool mmc35240_needs_compensation(enum mmc35240_chipset chipset)
> +{
> +	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 +271,10 @@ 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 RESET/SET sequence
> @@ -240,6 +295,9 @@ 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)
> @@ -301,9 +359,51 @@ 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)
> +{
> +	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];
> +		break;
> +	case AXIS_Z:
> +		*val = (raw[AXIS_Z] - nfo) * 1000 / sens[AXIS_Z];
> +		break;
> +	default:
> +		return -EINVAL;
> +	}
> +
> +	return 0;
> +}
> +
> +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.
>   *
>   * @data: device private data
>   * @index: axis index for which we want the conversion
> @@ -312,40 +412,42 @@ 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_x, raw_y, raw_z;
> -	int sens_x, sens_y, sens_z;
Sensible change to an array, but it's not really part of the adding
of the new device, so I'd have slighty preferred it as a precursor
patch to this main one.
> +	int raw[3];
> +	int sens[3];
>  	int nfo;
> +	int ret;
> +	int id = data->chipset;
>  
> -	raw_x = le16_to_cpu(buf[AXIS_X]);
> -	raw_y = le16_to_cpu(buf[AXIS_Y]);
> -	raw_z = le16_to_cpu(buf[AXIS_Z]);
> +	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_x = mmc35240_props_table[data->res].sens[AXIS_X];
> -	sens_y = mmc35240_props_table[data->res].sens[AXIS_Y];
> -	sens_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;
> +	nfo = mmc35240_props_table[id][data->res].nfo;
>  
> -	switch (index) {
> -	case AXIS_X:
> -		*val = (raw_x - nfo) * 1000 / sens_x;
> -		break;
> -	case AXIS_Y:
> -		*val = (raw_y - nfo) * 1000 / sens_y -
> -			(raw_z - nfo)  * 1000 / sens_z;
> -		break;
> -	case AXIS_Z:
> -		*val = (raw_y - nfo) * 1000 / sens_y +
> -			(raw_z - nfo) * 1000 / sens_z;
> -		break;
> +	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;
>  }
> @@ -366,7 +468,7 @@ 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;
> @@ -484,12 +586,27 @@ 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));
> @@ -508,11 +625,20 @@ 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;
> @@ -559,14 +685,16 @@ static const struct dev_pm_ops mmc35240_pm_ops = {
>  };
>  
>  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);
>  
> 

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