Re: [PATCH v2 3/5] IIO: Ingenic JZ47xx: Add touchscreen mode.

[Jonathan Cameron <jic23@kernel.org>]

On Sun, 26 Jan 2020 17:12:34 +0100
Artur Rojek <contact@artur-rojek.eu> wrote:

> The SADC component in JZ47xx SoCs provides support for touchscreen
> operations (pen position and pen down pressure) in single-ended and
> differential modes.
> 
> Of the known hardware to use this controller, GCW Zero and Anbernic RG-350
> utilize the touchscreen mode by having their joystick(s) attached to the
> X/Y positive/negative input pins.
> GCW Zero comes with a single joystick and is sufficiently handled with the
> currently implemented single-ended mode. Support for boards with two
> joysticks, where one is hooked up to Xn/Yn and the other to Xp/Yp channels
> will need to be provided in the future.
> 
> The touchscreen component of SADC takes a significant time to stabilize
> after first receiving the clock and a delay of 50ms has been empirically
> proven to be a safe value before data sampling can begin.
> 
> Signed-off-by: Artur Rojek <contact@artur-rojek.eu>
> Tested-by: Paul Cercueil <paul@crapouillou.net>
Great. I guess it does all work without registering a pointless kfifo
based userspace interface  :)

I'll pick this up once the dt issue in the next patch is resolved.

Thanks,

Jonathan

> ---
> 
>  Changes:
> 
>  v2: - improve description of the touchscreen mode,
>      - get rid of the unneeded kfifo,
>      - drop IIO_BUFFER_CB from Kconfig,
>      - remove extended names from the touchscreen channels
> 
>  drivers/iio/adc/Kconfig       |   1 +
>  drivers/iio/adc/ingenic-adc.c | 110 +++++++++++++++++++++++++++++++++-
>  2 files changed, 109 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/iio/adc/Kconfig b/drivers/iio/adc/Kconfig
> index 5d8540b7b427..7381b91303c5 100644
> --- a/drivers/iio/adc/Kconfig
> +++ b/drivers/iio/adc/Kconfig
> @@ -446,6 +446,7 @@ config INA2XX_ADC
>  config INGENIC_ADC
>  	tristate "Ingenic JZ47xx SoCs ADC driver"
>  	depends on MIPS || COMPILE_TEST
> +	select IIO_BUFFER
>  	help
>  	  Say yes here to build support for the Ingenic JZ47xx SoCs ADC unit.
>  
> diff --git a/drivers/iio/adc/ingenic-adc.c b/drivers/iio/adc/ingenic-adc.c
> index 7a24bc1dabe1..fcc29deeaf0b 100644
> --- a/drivers/iio/adc/ingenic-adc.c
> +++ b/drivers/iio/adc/ingenic-adc.c
> @@ -8,7 +8,10 @@
>  
>  #include <dt-bindings/iio/adc/ingenic,adc.h>
>  #include <linux/clk.h>
> +#include <linux/iio/buffer.h>
>  #include <linux/iio/iio.h>
> +#include <linux/iio/kfifo_buf.h>
Don't think you are using this any more..

> +#include <linux/interrupt.h>
>  #include <linux/io.h>
>  #include <linux/iopoll.h>
>  #include <linux/kernel.h>
> @@ -20,6 +23,8 @@
>  #define JZ_ADC_REG_CFG			0x04
>  #define JZ_ADC_REG_CTRL			0x08
>  #define JZ_ADC_REG_STATUS		0x0c
> +#define JZ_ADC_REG_ADSAME		0x10
> +#define JZ_ADC_REG_ADWAIT		0x14
>  #define JZ_ADC_REG_ADTCH		0x18
>  #define JZ_ADC_REG_ADBDAT		0x1c
>  #define JZ_ADC_REG_ADSDAT		0x20
> @@ -28,6 +33,9 @@
>  #define JZ_ADC_REG_ENABLE_PD		BIT(7)
>  #define JZ_ADC_REG_CFG_AUX_MD		(BIT(0) | BIT(1))
>  #define JZ_ADC_REG_CFG_BAT_MD		BIT(4)
> +#define JZ_ADC_REG_CFG_PULL_UP(n)	((n) << 16)
> +#define JZ_ADC_REG_CFG_SAMPLE_NUM(n)	((n) << 10)
> +#define JZ_ADC_REG_CFG_TOUCH_OPS_MASK	(BIT(31) | GENMASK(23, 10))
>  #define JZ_ADC_REG_ADCLK_CLKDIV_LSB	0
>  #define JZ4725B_ADC_REG_ADCLK_CLKDIV10US_LSB	16
>  #define JZ4770_ADC_REG_ADCLK_CLKDIV10US_LSB	8
> @@ -44,6 +52,14 @@
>  #define JZ4770_ADC_BATTERY_VREF			6600
>  #define JZ4770_ADC_BATTERY_VREF_BITS		12
>  
> +#define JZ_ADC_IRQ_AUX			BIT(0)
> +#define JZ_ADC_IRQ_BATTERY		BIT(1)
> +#define JZ_ADC_IRQ_TOUCH		BIT(2)
> +#define JZ_ADC_IRQ_PEN_DOWN		BIT(3)
> +#define JZ_ADC_IRQ_PEN_UP		BIT(4)
> +#define JZ_ADC_IRQ_PEN_DOWN_SLEEP	BIT(5)
> +#define JZ_ADC_IRQ_SLEEP		BIT(7)
> +
>  struct ingenic_adc;
>  
>  struct ingenic_adc_soc_data {
> @@ -411,6 +427,28 @@ static const struct iio_info ingenic_adc_info = {
>  };
>  
>  static const struct iio_chan_spec ingenic_channels[] = {
> +	{
> +		.type = IIO_POSITIONRELATIVE,
> +		.indexed = 1,
> +		.channel = INGENIC_ADC_TOUCH_XP,
> +		.scan_index = 0,
> +		.scan_type = {
> +			.sign = 'u',
> +			.realbits = 12,
> +			.storagebits = 16
> +		},
> +	},
> +	{
> +		.type = IIO_POSITIONRELATIVE,
> +		.indexed = 1,
> +		.channel = INGENIC_ADC_TOUCH_YP,
> +		.scan_index = 1,
> +		.scan_type = {
> +			.sign = 'u',
> +			.realbits = 12,
> +			.storagebits = 16
> +		},
> +	},
>  	{
>  		.extend_name = "aux",
>  		.type = IIO_VOLTAGE,
> @@ -418,6 +456,7 @@ static const struct iio_chan_spec ingenic_channels[] = {
>  				      BIT(IIO_CHAN_INFO_SCALE),
>  		.indexed = 1,
>  		.channel = INGENIC_ADC_AUX,
> +		.scan_index = -1
>  	},
>  	{
>  		.extend_name = "battery",
> @@ -428,6 +467,7 @@ static const struct iio_chan_spec ingenic_channels[] = {
>  						BIT(IIO_CHAN_INFO_SCALE),
>  		.indexed = 1,
>  		.channel = INGENIC_ADC_BATTERY,
> +		.scan_index = -1
>  	},
>  	{ /* Must always be last in the array. */
>  		.extend_name = "aux2",
> @@ -436,16 +476,69 @@ static const struct iio_chan_spec ingenic_channels[] = {
>  				      BIT(IIO_CHAN_INFO_SCALE),
>  		.indexed = 1,
>  		.channel = INGENIC_ADC_AUX2,
> +		.scan_index = -1
>  	},
>  };
>  
> +static int ingenic_adc_buffer_enable(struct iio_dev *iio_dev)
> +{
> +	struct ingenic_adc *adc = iio_priv(iio_dev);
> +
> +	clk_enable(adc->clk);
> +	/* It takes significant time for the touchscreen hw to stabilize. */
> +	msleep(50);
> +	ingenic_adc_set_config(adc, JZ_ADC_REG_CFG_TOUCH_OPS_MASK,
> +			       JZ_ADC_REG_CFG_SAMPLE_NUM(4) |
> +			       JZ_ADC_REG_CFG_PULL_UP(4));
> +	writew(80, adc->base + JZ_ADC_REG_ADWAIT);
> +	writew(2, adc->base + JZ_ADC_REG_ADSAME);
> +	writeb((u8)~JZ_ADC_IRQ_TOUCH, adc->base + JZ_ADC_REG_CTRL);
> +	writel(0, adc->base + JZ_ADC_REG_ADTCH);
> +	ingenic_adc_enable(adc, 2, true);
> +
> +	return 0;
> +}
> +
> +static int ingenic_adc_buffer_disable(struct iio_dev *iio_dev)
> +{
> +	struct ingenic_adc *adc = iio_priv(iio_dev);
> +
> +	ingenic_adc_enable(adc, 2, false);
> +	writeb(0xff, adc->base + JZ_ADC_REG_CTRL);
> +	writeb(0xff, adc->base + JZ_ADC_REG_STATUS);
> +	ingenic_adc_set_config(adc, JZ_ADC_REG_CFG_TOUCH_OPS_MASK, 0);
> +	writew(0, adc->base + JZ_ADC_REG_ADSAME);
> +	writew(0, adc->base + JZ_ADC_REG_ADWAIT);
> +	clk_disable(adc->clk);
> +
> +	return 0;
> +}
> +
> +static const struct iio_buffer_setup_ops ingenic_buffer_setup_ops = {
> +	.postenable = &ingenic_adc_buffer_enable,
> +	.predisable = &ingenic_adc_buffer_disable
> +};
> +
> +static irqreturn_t ingenic_adc_irq(int irq, void *data)
> +{
> +	struct iio_dev *iio_dev = data;
> +	struct ingenic_adc *adc = iio_priv(iio_dev);
> +	u32 tdat;
> +
> +	tdat = readl(adc->base + JZ_ADC_REG_ADTCH);
> +	iio_push_to_buffers(iio_dev, &tdat);
> +	writeb(JZ_ADC_IRQ_TOUCH, adc->base + JZ_ADC_REG_STATUS);
> +
> +	return IRQ_HANDLED;
> +}
> +
>  static int ingenic_adc_probe(struct platform_device *pdev)
>  {
>  	struct device *dev = &pdev->dev;
>  	struct iio_dev *iio_dev;
>  	struct ingenic_adc *adc;
>  	const struct ingenic_adc_soc_data *soc_data;
> -	int ret;
> +	int irq, ret;
>  
>  	soc_data = device_get_match_data(dev);
>  	if (!soc_data)
> @@ -460,6 +553,18 @@ static int ingenic_adc_probe(struct platform_device *pdev)
>  	mutex_init(&adc->aux_lock);
>  	adc->soc_data = soc_data;
>  
> +	irq = platform_get_irq(pdev, 0);
> +	if (irq < 0) {
> +		dev_err(dev, "Failed to get irq: %d\n", irq);
> +		return irq;
> +	}
> +	ret = devm_request_irq(dev, irq, ingenic_adc_irq, 0,
> +			       dev_name(dev), iio_dev);
> +	if (ret < 0) {
> +		dev_err(dev, "Failed to request irq: %d\n", ret);
> +		return ret;
> +	}
> +
>  	adc->base = devm_platform_ioremap_resource(pdev, 0);
>  	if (IS_ERR(adc->base))
>  		return PTR_ERR(adc->base);
> @@ -499,7 +604,8 @@ static int ingenic_adc_probe(struct platform_device *pdev)
>  
>  	iio_dev->dev.parent = dev;
>  	iio_dev->name = "jz-adc";
> -	iio_dev->modes = INDIO_DIRECT_MODE;
> +	iio_dev->modes = INDIO_DIRECT_MODE | INDIO_BUFFER_SOFTWARE;
> +	iio_dev->setup_ops = &ingenic_buffer_setup_ops;
>  	iio_dev->channels = ingenic_channels;
>  	iio_dev->num_channels = ARRAY_SIZE(ingenic_channels);
>  	/* Remove AUX2 from the list of supported channels. */