Re: [PATCH v4] iio: magnetometer: mag3110: Add ability to run in continuous mode

[Jonathan Cameron <jic23@kernel.org>]

On Tue, 8 May 2018 15:59:54 +0800
Richard Tresidder <rtresidd@electromag.com.au> wrote:

> Adds the ability to run the Mag3110 in continuous mode to speed up the sampling rate.
> Depending on the sampling rate requested the device can be put in or out of continuous mode automatically.
> Shifting out of continuous mode requires a potential 1 / ODR wait which is also implemented.
> Modified the sleep method when data is not ready to allow for sampling > 50sps to work.
> 
> Signed-off-by: Richard Tresidder <rtresidd@electromag.com.au>
One general thing.  When sending a new version of a patch, don't
reply to the previous version.  In any threading email client things
can get awfully hard to follow so it is 'mostly' preferred to do
a new thread for a new version.

There are a couple of trivial things about comment syntax but
otherwise this looks good.

Applied, with minor tweaks to the togreg branch of iio.git and pushed
out as testing for the autobuilders to play with it.

Thanks,

Jonathan

> ---
> v4: Changes from v3:
>   * Use GENMASK for MAG3110_SYSMOD_MODE_MASK
>   * Fix some missing spaces and blank lines
>   * Fix cast truncates bits from const compile warning
>   * Fix some slightly long lines
> 
> v3: Changes from v2:
>   * Move mag3110_standby function due to precedence issue (missed during cleanup)
> 
> v2: Changes from v1:
>   * Remove whitespace changes and tidy up changes
> 
> drivers/iio/magnetometer/mag3110.c | 156 ++++++++++++++++++++++++++++++++-----
> 1 file changed, 138 insertions(+), 18 deletions(-)
>  
> diff --git a/drivers/iio/magnetometer/mag3110.c b/drivers/iio/magnetometer/mag3110.c
> index b34ace7..3f48282 100644
> --- a/drivers/iio/magnetometer/mag3110.c
> +++ b/drivers/iio/magnetometer/mag3110.c
> @@ -26,6 +26,7 @@
>  #define MAG3110_OUT_Y 0x03
>  #define MAG3110_OUT_Z 0x05
>  #define MAG3110_WHO_AM_I 0x07
> +#define MAG3110_SYSMOD 0x08
>  #define MAG3110_OFF_X 0x09 /* MSB first */
>  #define MAG3110_OFF_Y 0x0b
>  #define MAG3110_OFF_Z 0x0d
> @@ -39,6 +40,8 @@
>  #define MAG3110_CTRL_DR_SHIFT 5
>  #define MAG3110_CTRL_DR_DEFAULT 0
>  
> +#define MAG3110_SYSMOD_MODE_MASK GENMASK(1, 0)
> +
>  #define MAG3110_CTRL_TM BIT(1) /* trigger single measurement */
>  #define MAG3110_CTRL_AC BIT(0) /* continuous measurements */
>  
> @@ -52,17 +55,20 @@ struct mag3110_data {
>  	struct i2c_client *client;
>  	struct mutex lock;
>  	u8 ctrl_reg1;
> +	int sleep_val;
>  };
>  
>  static int mag3110_request(struct mag3110_data *data)
>  {
>  	int ret, tries = 150;
>  
> -	/* trigger measurement */
> -	ret = i2c_smbus_write_byte_data(data->client, MAG3110_CTRL_REG1,
> -		data->ctrl_reg1 | MAG3110_CTRL_TM);
> -	if (ret < 0)
> -		return ret;
> +	if ((data->ctrl_reg1 & MAG3110_CTRL_AC) == 0) {
> +		/* trigger measurement */
> +		ret = i2c_smbus_write_byte_data(data->client, MAG3110_CTRL_REG1,
> +			data->ctrl_reg1 | MAG3110_CTRL_TM);
> +		if (ret < 0)
> +			return ret;
> +	}
>  
>  	while (tries-- > 0) {
>  		ret = i2c_smbus_read_byte_data(data->client, MAG3110_STATUS);
> @@ -71,7 +77,11 @@ static int mag3110_request(struct mag3110_data *data)
>  		/* wait for data ready */
>  		if ((ret & MAG3110_STATUS_DRDY) == MAG3110_STATUS_DRDY)
>  			break;
> -		msleep(20);
> +
> +		if (data->sleep_val <= 20)
> +			usleep_range(data->sleep_val * 250, data->sleep_val * 500);
> +		else
> +			msleep(20);
>  	}
>  
>  	if (tries < 0) {
> @@ -144,6 +154,115 @@ static int mag3110_get_samp_freq_index(struct mag3110_data *data,
>  		val2);
>  }
>  
> +static int mag3110_calculate_sleep(struct mag3110_data *data)
> +{
> +	int ret, i = data->ctrl_reg1 >> MAG3110_CTRL_DR_SHIFT;
> +
> +	if (mag3110_samp_freq[i][0] > 0)
> +		ret = 1000 / mag3110_samp_freq[i][0];
> +	else
> +		ret = 1000;
> +
> +	return ret == 0 ? 1 : ret;
> +}
> +
> +static int mag3110_standby(struct mag3110_data *data)
> +{
> +	return i2c_smbus_write_byte_data(data->client, MAG3110_CTRL_REG1,
> +		data->ctrl_reg1 & ~MAG3110_CTRL_AC);
> +}
> +
> +static int mag3110_wait_standby(struct mag3110_data *data)
> +{
> +	int ret, tries = 30;
> +
> +	/* Takes up to 1/ODR to come out of active mode into stby

The curious world of the kernel is that there are two accepted multi line
comment syntax options.  This one is only used (more or less) in the net
tree, everyone else sticks to the
/*
 * Takes

I'll fix up if I don't find anything 'more material'.

> +	 * Longest expected period is 12.5seconds.
> +	 * We'll sleep for 500ms between checks
> +	 */
> +	while (tries-- > 0) {
> +		ret = i2c_smbus_read_byte_data(data->client, MAG3110_SYSMOD);
> +		if (ret < 0) {
> +			dev_err(&data->client->dev, "i2c error\n");
> +			return ret;
> +		}
> +		/* wait for standby */
> +		if ((ret & MAG3110_SYSMOD_MODE_MASK) == 0)
> +			break;
> +
> +		msleep_interruptible(500);
> +	}
> +
> +	if (tries < 0) {
> +		dev_err(&data->client->dev, "device not entering standby mode\n");
> +		return -EIO;
> +	}
> +
> +	return 0;
> +}
> +
> +static int mag3110_active(struct mag3110_data *data)
> +{
> +	return i2c_smbus_write_byte_data(data->client, MAG3110_CTRL_REG1,
> +					 data->ctrl_reg1);
> +}
> +
> +/* returns >0 if active, 0 if in standby and <0 on error */
> +static int mag3110_is_active(struct mag3110_data *data)
> +{
> +	int reg;
> +
> +	reg = i2c_smbus_read_byte_data(data->client, MAG3110_CTRL_REG1);
> +	if (reg < 0)
> +		return reg;
> +
> +	return reg & MAG3110_CTRL_AC;
> +}
> +
> +static int mag3110_change_config(struct mag3110_data *data, u8 reg, u8 val)
> +{
> +	int ret;
> +	int is_active;
> +
> +	mutex_lock(&data->lock);
> +
> +	is_active = mag3110_is_active(data);
> +	if (is_active < 0) {
> +		ret = is_active;
> +		goto fail;
> +	}
> +
> +	/* config can only be changed when in standby */
> +	if (is_active > 0) {
> +		ret = mag3110_standby(data);
> +		if (ret < 0)
> +			goto fail;
> +	}
> +
> +	/* After coming out of active we must wait for the part

Comment syntax is wrong.  If that's all I find,
I'll fix up and apply...

> +	 * to transition to STBY. This can take up to 1 /ODR to occur
> +	 */
> +	ret = mag3110_wait_standby(data);
> +	if (ret < 0)
> +		goto fail;
> +
> +	ret = i2c_smbus_write_byte_data(data->client, reg, val);
> +	if (ret < 0)
> +		goto fail;
> +
> +	if (is_active > 0) {
> +		ret = mag3110_active(data);
> +		if (ret < 0)
> +			goto fail;
> +	}
> +
> +	ret = 0;
> +fail:
> +	mutex_unlock(&data->lock);
> +
> +	return ret;
> +}
> +
>  static int mag3110_read_raw(struct iio_dev *indio_dev,
>  			    struct iio_chan_spec const *chan,
>  			    int *val, int *val2, long mask)
> @@ -235,11 +354,15 @@ static int mag3110_write_raw(struct iio_dev *indio_dev,
>  			ret = -EINVAL;
>  			break;
>  		}
> -
> -		data->ctrl_reg1 &= ~MAG3110_CTRL_DR_MASK;
> +		data->ctrl_reg1 &= 0xff & ~MAG3110_CTRL_DR_MASK
> +					& ~MAG3110_CTRL_AC;
>  		data->ctrl_reg1 |= rate << MAG3110_CTRL_DR_SHIFT;
> -		ret = i2c_smbus_write_byte_data(data->client,
> -			MAG3110_CTRL_REG1, data->ctrl_reg1);
> +		data->sleep_val = mag3110_calculate_sleep(data);
> +		if (data->sleep_val < 40)
> +			data->ctrl_reg1 |= MAG3110_CTRL_AC;
> +
> +		ret = mag3110_change_config(data, MAG3110_CTRL_REG1,
> +					    data->ctrl_reg1);
>  		break;
>  	case IIO_CHAN_INFO_CALIBBIAS:
>  		if (val < -10000 || val > 10000) {
> @@ -337,12 +460,6 @@ static irqreturn_t mag3110_trigger_handler(int irq, void *p)
>  
>  static const unsigned long mag3110_scan_masks[] = {0x7, 0xf, 0};
>  
> -static int mag3110_standby(struct mag3110_data *data)
> -{
> -	return i2c_smbus_write_byte_data(data->client, MAG3110_CTRL_REG1,
> -		data->ctrl_reg1 & ~MAG3110_CTRL_AC);
> -}
> -
>  static int mag3110_probe(struct i2c_client *client,
>  			 const struct i2c_device_id *id)
>  {
> @@ -374,8 +491,11 @@ static int mag3110_probe(struct i2c_client *client,
>  	indio_dev->available_scan_masks = mag3110_scan_masks;
>  
>  	data->ctrl_reg1 = MAG3110_CTRL_DR_DEFAULT << MAG3110_CTRL_DR_SHIFT;
> -	ret = i2c_smbus_write_byte_data(client, MAG3110_CTRL_REG1,
> -		data->ctrl_reg1);
> +	data->sleep_val = mag3110_calculate_sleep(data);
> +	if (data->sleep_val < 40)
> +		data->ctrl_reg1 |= MAG3110_CTRL_AC;
> +
> +	ret = mag3110_change_config(data, MAG3110_CTRL_REG1, data->ctrl_reg1);
>  	if (ret < 0)
>  		return ret;
>  
>