Re: [PATCH 7/7] Staging/iio/adc/touchscreen/MXS: provide devicetree adaption

[Jonathan Cameron <jic23@kernel.org>]

The device tree list has moved, so I've changed the cc.

Few comments inline.  Basically I'd go for longer more
descriptive names when the abreviation isn't a really
well known common one.


Note I'm not all that familiar with device tree conventions
so may be barking up the wrong tree ;)
On 09/19/13 13:22, Juergen Beisert wrote:
> This is an RFC for the new touchscreen properties.
> 
> Signed-off-by: Juergen Beisert <jbe@pengutronix.de>
> CC: linux-arm-kernel@lists.infradead.org
> CC: devel@driverdev.osuosl.org
> CC: Marek Vasut <marex@denx.de>
> CC: Fabio Estevam <fabio.estevam@freescale.com>
> CC: Jonathan Cameron <jic23@cam.ac.uk>
> CC: devicetree-discuss@lists.ozlabs.org
> ---
>  .../bindings/staging/iio/adc/mxs-lradc.txt         | 36 ++++++++++++--
>  drivers/staging/iio/adc/mxs-lradc.c                | 57 ++++++++++++++--------
>  2 files changed, 67 insertions(+), 26 deletions(-)
> 
> diff --git a/Documentation/devicetree/bindings/staging/iio/adc/mxs-lradc.txt b/Documentation/devicetree/bindings/staging/iio/adc/mxs-lradc.txt
> index 4688205..ee05dc3 100644
> --- a/Documentation/devicetree/bindings/staging/iio/adc/mxs-lradc.txt
> +++ b/Documentation/devicetree/bindings/staging/iio/adc/mxs-lradc.txt
> @@ -1,7 +1,8 @@
>  * Freescale i.MX28 LRADC device driver
>  
>  Required properties:
> -- compatible: Should be "fsl,imx28-lradc"
> +- compatible: Should be "fsl,imx23-lradc" for i.MX23 SoC and "fsl,imx28-lradc"
> +              for i.MX28 SoC
>  - reg: Address and length of the register set for the device
>  - interrupts: Should contain the LRADC interrupts
>  
> @@ -9,13 +10,38 @@ Optional properties:
>  - fsl,lradc-touchscreen-wires: Number of wires used to connect the touchscreen
>                                 to LRADC. Valid value is either 4 or 5. If this
>                                 property is not present, then the touchscreen is
> -                               disabled.
Do we want that lradc prefix on these other properties?
> +                               disabled. 5 wires is valid for i.MX28 SoC only.
> +- fsl,ave-ctrl: number of samples per direction to calculate an average value.
> +                Allowed value is 1 ... 31, default is 4
This naming seems less than informative, what about fsl,average_num_samples of average_count
(ave isn't all that obvious an abrevaition of average).

> +- fsl,ave-delay: delay between consecutive samples. Allowed value is
> +                 1 ... 2047. It is used if 'fsl,ave-ctrl' > 1, counts at
> +                 2 kHz and its default is 2 (= 1 ms)
fsl,average_intersample_delay (I assume any limit of device tree property names is longer than that?)

> +- fsl,settling: delay between plate switch to next sample. Allowed value is
> +                1 ... 2047. It counts at 2 kHz and its default is
> +                10 (= 5 ms)
>  
> -Examples:
> +Example for i.MX23 SoC:
> +
> +	lradc@80050000 {
> +		compatible = "fsl,imx23-lradc";
> +		reg = <0x80050000 0x2000>;
> +		interrupts = <36 37 38 39 40 41 42 43 44>;
> +		status = "okay";
> +		fsl,lradc-touchscreen-wires = <4>;
> +		fsl,ave-ctrl = <4>;
> +		fsl,ave-delay = <2>;
> +		fsl,settling = <10>;
> +	};
> +
> +Example for i.MX28 SoC:
>  
>  	lradc@80050000 {
>  		compatible = "fsl,imx28-lradc";
>  		reg = <0x80050000 0x2000>;
> -		interrupts = <10 14 15 16 17 18 19
> -				20 21 22 23 24 25>;
> +		interrupts = <10 14 15 16 17 18 19 20 21 22 23 24 25>;
> +		status = "okay";
> +		fsl,lradc-touchscreen-wires = <5>;
> +		fsl,ave-ctrl = <4>;
> +		fsl,ave-delay = <2>;
> +		fsl,settling = <10>;
>  	};
> diff --git a/drivers/staging/iio/adc/mxs-lradc.c b/drivers/staging/iio/adc/mxs-lradc.c
> index 122475f..ffcb0dd 100644
> --- a/drivers/staging/iio/adc/mxs-lradc.c
> +++ b/drivers/staging/iio/adc/mxs-lradc.c
> @@ -1225,10 +1225,45 @@ MODULE_DEVICE_TABLE(of, mxs_lradc_dt_ids);
>  static int mxs_lradc_probe_touchscreen(struct mxs_lradc *lradc,
>  						struct device_node *lradc_node)
>  {
> -	/* TODO retrieve from device tree */
> +	int ret;
> +	u32 ts_wires = 0, adapt;
> +
> +	ret = of_property_read_u32(lradc_node, "fsl,lradc-touchscreen-wires",
> +				&ts_wires);
> +	if (ret)
> +		return -ENODEV; /* touchscreen feature disabled */
> +
> +	switch (ts_wires) {
> +	case 4:
> +		lradc->use_touchscreen = MXS_LRADC_TOUCHSCREEN_4WIRE;
> +		break;
> +	case 5:
> +		if (lradc->soc == IMX28_LRADC) {
> +			lradc->use_touchscreen = MXS_LRADC_TOUCHSCREEN_5WIRE;
> +			break;
> +		}
> +		/* fall through an error message for i.MX23 */
> +	default:
> +		dev_err(lradc->dev,
> +			"Unsupported number of touchscreen wires (%d)\n",
> +			ts_wires);
> +		return -EINVAL;
> +	}
> +
>  	lradc->over_sample_cnt = 4;
> +	ret = of_property_read_u32(lradc_node, "fsl,ave-ctrl", &adapt);
> +	if (ret == 0)
> +		lradc->over_sample_cnt = adapt;
> +
>  	lradc->over_sample_delay = 2;
> +	ret = of_property_read_u32(lradc_node, "fsl,ave-delay", &adapt);
> +	if (ret == 0)
> +		lradc->over_sample_delay = adapt;
> +
>  	lradc->settling_delay = 10;
> +	ret = of_property_read_u32(lradc_node, "fsl,settling", &adapt);
> +	if (ret == 0)
> +		lradc->settling_delay = adapt;
>  
>  	return 0;
>  }
> @@ -1244,7 +1279,6 @@ static int mxs_lradc_probe(struct platform_device *pdev)
>  	struct mxs_lradc *lradc;
>  	struct iio_dev *iio;
>  	struct resource *iores;
> -	uint32_t ts_wires = 0;
>  	int ret = 0, touch_ret;
>  	int i;
>  
> @@ -1267,25 +1301,6 @@ static int mxs_lradc_probe(struct platform_device *pdev)
>  
>  	touch_ret = mxs_lradc_probe_touchscreen(lradc, node);
>  
> -	/* Check if touchscreen is enabled in DT. */
> -	ret = of_property_read_u32(node, "fsl,lradc-touchscreen-wires",
> -				&ts_wires);
> -	if (ret)
> -		dev_info(dev, "Touchscreen not enabled.\n");
> -	else if (ts_wires == 4)
> -		lradc->use_touchscreen = MXS_LRADC_TOUCHSCREEN_4WIRE;
> -	else if (ts_wires == 5)
> -		lradc->use_touchscreen = MXS_LRADC_TOUCHSCREEN_5WIRE;
> -	else
> -		dev_warn(dev, "Unsupported number of touchscreen wires (%d)\n",
> -				ts_wires);
> -
> -	if ((lradc->soc == IMX23_LRADC) && (ts_wires == 5)) {
> -		dev_warn(dev, "No support for 5 wire touches on i.MX23\n");
> -		dev_warn(dev, "Falling back to 4 wire\n");
> -		ts_wires = 4;
> -	}
> -
>  	/* Grab all IRQ sources */
>  	for (i = 0; i < of_cfg->irq_count; i++) {
>  		lradc->irq[i] = platform_get_irq(pdev, i);
>