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Date:   Sun, 4 Mar 2018 18:26:04 +0530
From:   Himanshu Jha <himanshujha199640@gmail.com>
To:     Shreeya Patel <shreeya.patel23498@gmail.com>
Cc:     lars@metafoo.de, Michael.Hennerich@analog.com, jic23@kernel.org,
        knaack.h@gmx.de, pmeerw@pmeerw.net, gregkh@linuxfoundation.org,
        linux-iio@vger.kernel.org, devel@driverdev.osuosl.org,
        linux-kernel@vger.kernel.org, daniel.baluta@gmail.com
Subject: Re: [PATCH v3 1/4] Staging: iio: adis16209: Remove and add some
 comments and group the definitions
Message-ID: <20180304125604.GA7613@himanshu-Vostro-3559>
References: <cover.1520164945.git.shreeya.patel23498@gmail.com>
 <982742b1bb71d4d97c2f5edc6f95b85129d8667b.1520164945.git.shreeya.patel23498@gmail.com>
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Hi Shreeya,

On Sun, Mar 04, 2018 at 06:06:22PM +0530, Shreeya Patel wrote:
> Remove some unnecessay comments and group the control
> register and register field macros together.
> Some of the register names does not make it's puporse
> very clear and hence, add some comments for more
> information.
> Also there are certain unit based comments which are not
> providing sufficient information, so expand those comments.
> 
> Signed-off-by: Shreeya Patel <shreeya.patel23498@gmail.com>
> ---
> 
> Changes in v3
>   -This patch is the combination of two patches from the
> previous series. Also add some more comments.
> 
> 
>  drivers/staging/iio/accel/adis16209.c | 132 ++++++++++------------------------
>  1 file changed, 39 insertions(+), 93 deletions(-)
> 
> diff --git a/drivers/staging/iio/accel/adis16209.c b/drivers/staging/iio/accel/adis16209.c
> index 151120f..d8aef9c 100644
> --- a/drivers/staging/iio/accel/adis16209.c
> +++ b/drivers/staging/iio/accel/adis16209.c
> @@ -21,135 +21,70 @@
>  #include <linux/iio/imu/adis.h>
>  
>  #define ADIS16209_STARTUP_DELAY_MS	220
> -
> -/* Flash memory write count */
>  #define ADIS16209_FLASH_CNT_REG		0x00
>  
> -/* Output, power supply */
> +/* Data Output Register Definitions */
>  #define ADIS16209_SUPPLY_OUT_REG	0x02
> -
> -/* Output, x-axis accelerometer */
>  #define ADIS16209_XACCL_OUT_REG		0x04
> -
> -/* Output, y-axis accelerometer */
>  #define ADIS16209_YACCL_OUT_REG		0x06
> -
>  /* Output, auxiliary ADC input */
>  #define ADIS16209_AUX_ADC_REG		0x08
> -
>  /* Output, temperature */
>  #define ADIS16209_TEMP_OUT_REG		0x0A
> -
> -/* Output, x-axis inclination */
> +/* Output, +/- 90 degrees X-axis inclination */
>  #define ADIS16209_XINCL_OUT_REG		0x0C
> -
> -/* Output, y-axis inclination */
>  #define ADIS16209_YINCL_OUT_REG		0x0E
> -
>  /* Output, +/-180 vertical rotational position */
>  #define ADIS16209_ROT_OUT_REG		0x10
>  
> -/* Calibration, x-axis acceleration offset null */
> +/*
> + * Calibration Register Definitions.
> + * Acceleration, inclination or rotation offset null.
> + */
>  #define ADIS16209_XACCL_NULL_REG	0x12
> -
> -/* Calibration, y-axis acceleration offset null */
>  #define ADIS16209_YACCL_NULL_REG	0x14
> -
> -/* Calibration, x-axis inclination offset null */
>  #define ADIS16209_XINCL_NULL_REG	0x16
> -
> -/* Calibration, y-axis inclination offset null */
>  #define ADIS16209_YINCL_NULL_REG	0x18
> -
> -/* Calibration, vertical rotation offset null */
>  #define ADIS16209_ROT_NULL_REG		0x1A
>  
> -/* Alarm 1 amplitude threshold */
> +/* Alarm Register Definitions */
>  #define ADIS16209_ALM_MAG1_REG		0x20
> -
> -/* Alarm 2 amplitude threshold */
>  #define ADIS16209_ALM_MAG2_REG		0x22
> -
> -/* Alarm 1, sample period */
>  #define ADIS16209_ALM_SMPL1_REG		0x24
> -
> -/* Alarm 2, sample period */
>  #define ADIS16209_ALM_SMPL2_REG		0x26
> -
> -/* Alarm control */
>  #define ADIS16209_ALM_CTRL_REG		0x28
>  
> -/* Auxiliary DAC data */
>  #define ADIS16209_AUX_DAC_REG		0x30
> -
> -/* General-purpose digital input/output control */
>  #define ADIS16209_GPIO_CTRL_REG		0x32
> -
> -/* Miscellaneous control */
> -#define ADIS16209_MSC_CTRL_REG		0x34
> -
> -/* Internal sample period (rate) control */
>  #define ADIS16209_SMPL_PRD_REG		0x36
> -
> -/* Operation, filter configuration */
>  #define ADIS16209_AVG_CNT_REG		0x38
> -
> -/* Operation, sleep mode control */
>  #define ADIS16209_SLP_CNT_REG		0x3A
>  
> -/* Diagnostics, system status register */
> -#define ADIS16209_DIAG_STAT_REG		0x3C
> -
> -/* Operation, system command register */
> -#define ADIS16209_GLOB_CMD_REG		0x3E
> -
> -/* MSC_CTRL */
> -
> -/* Self-test at power-on: 1 = disabled, 0 = enabled */
> -#define ADIS16209_MSC_CTRL_PWRUP_SELF_TEST	BIT(10)
> -
> -/* Self-test enable */
> -#define ADIS16209_MSC_CTRL_SELF_TEST_EN	        BIT(8)
> -
> -/* Data-ready enable: 1 = enabled, 0 = disabled */
> -#define ADIS16209_MSC_CTRL_DATA_RDY_EN	        BIT(2)
> -
> +#define ADIS16209_MSC_CTRL_REG			0x34
> +#define  ADIS16209_MSC_CTRL_PWRUP_SELF_TEST	BIT(10)
> +#define  ADIS16209_MSC_CTRL_SELF_TEST_EN	BIT(8)
> +#define  ADIS16209_MSC_CTRL_DATA_RDY_EN		BIT(2)
>  /* Data-ready polarity: 1 = active high, 0 = active low */
> -#define ADIS16209_MSC_CTRL_ACTIVE_HIGH	        BIT(1)
> +#define  ADIS16209_MSC_CTRL_ACTIVE_HIGH		BIT(1)
> +#define  ADIS16209_MSC_CTRL_DATA_RDY_DIO2	BIT(0)
>  
> -/* Data-ready line selection: 1 = DIO2, 0 = DIO1 */
> -#define ADIS16209_MSC_CTRL_DATA_RDY_DIO2	BIT(0)
> -
> -/* DIAG_STAT */
> -
> -/* Alarm 2 status: 1 = alarm active, 0 = alarm inactive */
> -#define ADIS16209_DIAG_STAT_ALARM2        BIT(9)
> -
> -/* Alarm 1 status: 1 = alarm active, 0 = alarm inactive */
> -#define ADIS16209_DIAG_STAT_ALARM1        BIT(8)
> -
> -/* Self-test diagnostic error flag: 1 = error condition, 0 = normal operation */
> +#define ADIS16209_DIAG_STAT_REG			0x3C
> +#define  ADIS16209_DIAG_STAT_ALARM2		BIT(9)
> +#define  ADIS16209_DIAG_STAT_ALARM1		BIT(8)
>  #define ADIS16209_DIAG_STAT_SELFTEST_FAIL_BIT	5
> -
> -/* SPI communications failure */
>  #define ADIS16209_DIAG_STAT_SPI_FAIL_BIT	3
> -
> -/* Flash update failure */
>  #define ADIS16209_DIAG_STAT_FLASH_UPT_BIT	2
> -
>  /* Power supply above 3.625 V */
>  #define ADIS16209_DIAG_STAT_POWER_HIGH_BIT	1
> -
>  /* Power supply below 3.15 V */
>  #define ADIS16209_DIAG_STAT_POWER_LOW_BIT	0
>  
> -/* GLOB_CMD */
> -
> -#define ADIS16209_GLOB_CMD_SW_RESET	BIT(7)
> -#define ADIS16209_GLOB_CMD_CLEAR_STAT	BIT(4)
> -#define ADIS16209_GLOB_CMD_FACTORY_CAL	BIT(1)
> +#define ADIS16209_GLOB_CMD_REG			0x3E
> +#define  ADIS16209_GLOB_CMD_SW_RESET		BIT(7)
> +#define  ADIS16209_GLOB_CMD_CLEAR_STAT		BIT(4)
> +#define  ADIS16209_GLOB_CMD_FACTORY_CAL		BIT(1)
>  
> -#define ADIS16209_ERROR_ACTIVE          BIT(14)
> +#define ADIS16209_ERROR_ACTIVE			BIT(14)
>  
>  enum adis16209_scan {
>  	ADIS16209_SCAN_SUPPLY,
> @@ -226,24 +161,38 @@ static int adis16209_read_raw(struct iio_dev *indio_dev,
>  				*val2 = 610500; /* 0.6105 mV */
>  			return IIO_VAL_INT_PLUS_MICRO;
>  		case IIO_TEMP:
> -			*val = -470; /* -0.47 C */
> +			*val = -470;
>  			*val2 = 0;
>  			return IIO_VAL_INT_PLUS_MICRO;
>  		case IIO_ACCEL:
> +			/*
> +			 * IIO base unit for sensitivity of accelerometer
> +			 * is milli g.
> +			 * 1 LSB represents 0.244 mg.
> +			 */
>  			*val = 0;
> -			*val2 = IIO_G_TO_M_S_2(244140); /* 0.244140 mg */
> +			*val2 = IIO_G_TO_M_S_2(244140);
>  			return IIO_VAL_INT_PLUS_NANO;
>  		case IIO_INCLI:
>  		case IIO_ROT:
> +			/*
> +			 * IIO base units for rotation are degrees.
> +			 * 1 LSB represents 0.025 milli degrees.
> +			 */
>  			*val = 0;
> -			*val2 = 25000; /* 0.025 degree */
> +			*val2 = 25000;
>  			return IIO_VAL_INT_PLUS_MICRO;
>  		default:
>  			return -EINVAL;
>  		}
>  		break;
>  	case IIO_CHAN_INFO_OFFSET:
> -		*val = 25000 / -470 - 0x4FE; /* 25 C = 0x4FE */
> +		/*
> +		 * The raw ADC value is 0x4FE when the temperature
> +		 * is 45 degrees and the scale factor per milli
> +		 * degree celcius is -470.

Are you sure it is *45 degrees* and not *25 degrees* instead ?

As I can clearly see from the datasheet :

"sensitivity = −0.47°/LSB, 25°C = 1278 LSB = 0x04FE"

Please check it :)

I found this because I'm also doing a similar cleanup for adis16201.

-- 
Thanks
Himanshu Jha