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

[Jonathan Cameron <jic23@jic23.retrosnub.co.uk>]

On Sun,  5 Jan 2020 01:16:37 +0100
Artur Rojek <contact@artur-rojek.eu> wrote:

> Implement support for the touchscreen mode found in JZ47xx SoCs ADC.
This needs more description.  

Looks like it enables a kfifo and also selects the callback buffer
stuff to run with a generic touchscreen iio-> input driver.

A few other bits inline, but basically fine.

I've never really thought about whether we support a CB buffer
without anything on the IIO side.   That should be possible,
but I'm not sure what odd corner cases will turn up.  I'm guessing
there are some, or you'd not have bothered exposing it here?

Thanks

Jonathan


> 
> Signed-off-by: Artur Rojek <contact@artur-rojek.eu>
> Tested-by: Paul Cercueil <paul@crapouillou.net>
> ---
>  drivers/iio/adc/Kconfig       |   3 +
>  drivers/iio/adc/ingenic-adc.c | 120 +++++++++++++++++++++++++++++++++-
>  2 files changed, 121 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/iio/adc/Kconfig b/drivers/iio/adc/Kconfig
> index 5d8540b7b427..dabbf15032af 100644
> --- a/drivers/iio/adc/Kconfig
> +++ b/drivers/iio/adc/Kconfig
> @@ -446,6 +446,9 @@ config INA2XX_ADC
>  config INGENIC_ADC
>  	tristate "Ingenic JZ47xx SoCs ADC driver"
>  	depends on MIPS || COMPILE_TEST
> +	select IIO_BUFFER
> +	select IIO_BUFFER_CB

Feels like IIO_BUFFER_CB should be selected by the driver that
uses that functionality rather than this one.

> +	select IIO_KFIFO_BUF
>  	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..4dbf15fdd95d 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>
> +#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 +427,30 @@ static const struct iio_info ingenic_adc_info = {
>  };
>  
>  static const struct iio_chan_spec ingenic_channels[] = {
> +	{
> +		.extend_name = "touchscreen_xp",

Note that adding extended names:

1) Needs documenting as it create ABI - so something in
Documentation/ABI/testing/sysfs-bus-iio-*

2) Breaks any generic userspace application.

Why can't we use modified and an axis to identify this?


> +		.type = IIO_POSITIONRELATIVE,
> +		.indexed = 1,
> +		.channel = INGENIC_ADC_TOUCH_XP,
> +		.scan_index = 0,
> +		.scan_type = {
> +			.sign = 'u',
> +			.realbits = 12,
> +			.storagebits = 16
> +		},
> +	},
> +	{
> +		.extend_name = "touchscreen_yp",
> +		.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 +458,7 @@ 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 +469,7 @@ 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 +478,70 @@ 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;
> +	struct iio_buffer *buffer;
> +	int irq, ret;
>  
>  	soc_data = device_get_match_data(dev);
>  	if (!soc_data)
> @@ -460,6 +556,18 @@ 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 +607,8 @@ 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. */
> @@ -507,6 +616,13 @@ static int ingenic_adc_probe(struct platform_device *pdev)
>  		iio_dev->num_channels -= 1;
>  	iio_dev->info = &ingenic_adc_info;
>  
> +	buffer = devm_iio_kfifo_allocate(dev);
> +	if (!buffer) {
> +		dev_err(dev, "Unable to add IIO buffer\n");
> +		return -ENOMEM;
> +	}
> +	iio_device_attach_buffer(iio_dev, buffer);
> +
>  	ret = devm_iio_device_register(dev, iio_dev);
>  	if (ret)
>  		dev_err(dev, "Unable to register IIO device\n");