Subject: [V4] [TWL4030 MADC] Fix ADC[3:6] readings

From: [email-masked] (Jonathan Cameron)
Date: Sat, 8 Aug 2015 16:15:46 +0100

On 04/08/15 19:15, 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]>
I'd ideally like an ack from the driver author or Sebastian as this isn't
a driver I'm particular familiar with.

Also, for future reference, patches should be titled something like
[Patch v4] iio: twl4030 madc: Fix ADC[3:6] readings.
(the patch bit is standard, the rest is iio convention)

Jonathan

> ---
>  drivers/iio/adc/twl4030-madc.c | 34 ++++++++++++++++++++++++++++++++++
>  1 file changed, 34 insertions(+)
> 
> diff --git a/drivers/iio/adc/twl4030-madc.c b/drivers/iio/adc/twl4030-madc.c
> index 94c5f05..8c58498 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;
> @@ -842,6 +848,32 @@ static int twl4030_madc_probe(struct platform_device *pdev)
>  	}
>  	twl4030_madc = madc;
>  
> +	/* 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");
> +
>  	ret = iio_device_register(iio_dev);
>  	if (ret) {
>  		dev_err(&pdev->dev, "could not register iio device\n");
> @@ -867,6 +899,8 @@ 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);
> +
>  	return 0;
>  }
>  
>