Re: [PATCH v3] iio: magnetometer: mag3110: Add ability to run in continuous mode

[Jonathan Cameron <jic23@kernel.org>]

On Mon, 7 May 2018 12:08:35 +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>

Hi Richard, much better on the formatting (though the html emails weren't
great before this ;)

Anyhow, one comment I made in v1 review that you missed.

Jonathan

> ---
> diff --git a/drivers/iio/magnetometer/mag3110.c b/drivers/iio/magnetometer/mag3110.c
> index b34ace7..a8ad598 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 (BIT(1) | BIT(0))

I commented on this in V1.  Please fix. This would be fine
if it were two one bit fields, it's not so use GENMASK to
remove the false semantic meaning.

> +
>  #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 +154,112 @@ 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 
> +		 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 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 +351,13 @@ static int mag3110_write_raw(struct iio_dev *indio_dev,
>  			ret = -EINVAL;
>  			break;
>  		}
> -
> -		data->ctrl_reg1 &= ~MAG3110_CTRL_DR_MASK;
> +		data->ctrl_reg1 &= ~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 +455,6 @@ 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 +486,11 @@ 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;
> 
> 
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