Subject: [V3] [TWL4030 MADC] Fix ADC[3:6] readings

From: [email-masked] (Jonathan Cameron)
Date: Sun, 2 Aug 2015 17:55:17 +0100

On 21/07/15 01:49, Adam YH Lee wrote:
> MADC[3:6] reads incorrect values without these two following changes:
> 
> - enable the 3v1 bias regulator for ADC[3:6]
> - configure ADC[3:6] lines as input, not as USB
> 
> Signed-off-by: Adam YH Lee <[email-masked]>
> ---
>  drivers/iio/adc/twl4030-madc.c | 36 ++++++++++++++++++++++++++++++++++++
>  1 file changed, 36 insertions(+)
> 
> diff --git a/drivers/iio/adc/twl4030-madc.c b/drivers/iio/adc/twl4030-madc.c
> index 94c5f05..ae33eba 100644
> --- a/drivers/iio/adc/twl4030-madc.c
> +++ b/drivers/iio/adc/twl4030-madc.c
> @@ -45,13 +45,18 @@
>  #include <linux/types.h>
>  #include <linux/gfp.h>
>  #include <linux/err.h>
> +#include <linux/regulator/consumer.h>
>  
>  #include <linux/iio/iio.h>
>  
> +#define TWL4030_USB_SEL_MADC_MCPC	(1<<3)
> +#define TWL4030_USB_CARKIT_ANA_CTRL	0xBB
> +
>  /**
>   * struct twl4030_madc_data - a container for madc info
>   * @dev:		Pointer to device structure for madc
>   * @lock:		Mutex protecting this data structure
> + * @regulator:		Pointer to bias regulator for madc
>   * @requests:		Array of request struct corresponding to SW1, SW2 and RT
>   * @use_second_irq:	IRQ selection (main or co-processor)
>   * @imr:		Interrupt mask register of MADC
> @@ -60,6 +65,7 @@
>  struct twl4030_madc_data {
>  	struct device *dev;
>  	struct mutex lock;	/* mutex protecting this data structure */
> +	struct regulator *usb3v1;
>  	struct twl4030_madc_request requests[TWL4030_MADC_NUM_METHODS];
>  	bool use_second_irq;
>  	u8 imr;
> @@ -848,6 +854,33 @@ static int twl4030_madc_probe(struct platform_device *pdev)
>  		goto err_i2c;
>  	}
>  
At this point in the driver the userspace (an in kernel) interfaces to read
from the device are exposed. Thus if you need this stuff set up right, it
wants to be done before the iio_device_register call.
> +	/* Configure MADC[3:6] */
> +	ret = twl_i2c_read_u8(TWL_MODULE_USB, &regval,
> +			TWL4030_USB_CARKIT_ANA_CTRL);
> +	if (ret) {
> +		dev_err(&pdev->dev, "unable to read reg CARKIT_ANA_CTRL  0x%X\n",
> +				TWL4030_USB_CARKIT_ANA_CTRL);
> +		goto err_i2c;
> +	}
> +	regval |= TWL4030_USB_SEL_MADC_MCPC;
> +	ret = twl_i2c_write_u8(TWL_MODULE_USB, regval,
> +				 TWL4030_USB_CARKIT_ANA_CTRL);
> +	if (ret) {
> +		dev_err(&pdev->dev, "unable to write reg CARKIT_ANA_CTRL 0x%X\n",
> +				TWL4030_USB_CARKIT_ANA_CTRL);
> +		goto err_i2c;
> +	}
> +
> +
> +	/* Enable 3v1 bias regulator for MADC[3:6] */
> +	madc->usb3v1 = devm_regulator_get(madc->dev, "vusb3v1");
> +	if (IS_ERR(madc->usb3v1))
> +		return -ENODEV;
> +
> +	ret = regulator_enable(madc->usb3v1);
> +	if (ret)
> +		dev_err(madc->dev, "could not enable 3v1 bias regulator\n");
> +
>  	return 0;
>  
>  err_i2c:
> @@ -867,6 +900,9 @@ static int twl4030_madc_remove(struct platform_device *pdev)
>  	twl4030_madc_set_current_generator(madc, 0, 0);
>  	twl4030_madc_set_power(madc, 0);
>  
> +	regulator_disable(madc->usb3v1);
> +	devm_regulator_put(madc->usb3v1);
The whole point of devm_ allocators (or in this case _gets) is that when
the driver is removed they are cleaned up automatically.  Hence you don't
need them in your remove call.  Obviously it also clears up the error
handling in probe as well.
> +
>  	return 0;
>  }