Re: [PATCH 1/5] input: Add new sun4i-ts driver for Allwinner sunxi SoC's rtp controller

[Dmitry Torokhov <dmitry.torokhov@gmail.com>]

Hi Hans,

On Tue, Dec 24, 2013 at 11:24:03PM +0100, Hans de Goede wrote:
> Note the sun4i-ts controller is capable of detecting a second touch, but when
> a second touch is present then the accuracy becomes so bad the reported touch
> location is not useable.
> 
> The original android driver contains some complicated heuristics using the
> aprox. distance between the 2 touches to see if the user is making a pinch
> open / close movement, and then reports emulated multi-touch events around
> the last touch coordinate (as the dual-touch coordinates are worthless).
> 
> These kinds of heuristics are just asking for trouble (and don't belong
> in the kernel). So this driver offers straight forward, reliable single
> touch functionality only.
> 
> Signed-off-by: Hans de Goede <hdegoede@redhat.com>
> ---
>  drivers/input/touchscreen/Kconfig    |  10 ++
>  drivers/input/touchscreen/Makefile   |   1 +
>  drivers/input/touchscreen/sun4i-ts.c | 272 +++++++++++++++++++++++++++++++++++
>  3 files changed, 283 insertions(+)
>  create mode 100644 drivers/input/touchscreen/sun4i-ts.c
> 
> diff --git a/drivers/input/touchscreen/Kconfig b/drivers/input/touchscreen/Kconfig
> index 961d58d..95023de 100644
> --- a/drivers/input/touchscreen/Kconfig
> +++ b/drivers/input/touchscreen/Kconfig
> @@ -906,6 +906,16 @@ config TOUCHSCREEN_STMPE
>  	  To compile this driver as a module, choose M here: the
>  	  module will be called stmpe-ts.
>  
> +config TOUCHSCREEN_SUN4I
> +	tristate "Allwinner sun4i resistive touchscreen controller support"
> +	depends on ARCH_SUNXI
> +	help
> +	  This selects support for the resistive touchscreen controller
> +	  found on Allwinner sunxi SoCs.
> +
> +	  To compile this driver as a module, choose M here: the
> +	  module will be called sun4i-ts.
> +
>  config TOUCHSCREEN_SUR40
>  	tristate "Samsung SUR40 (Surface 2.0/PixelSense) touchscreen"
>  	depends on USB
> diff --git a/drivers/input/touchscreen/Makefile b/drivers/input/touchscreen/Makefile
> index 62801f2..c8f7375 100644
> --- a/drivers/input/touchscreen/Makefile
> +++ b/drivers/input/touchscreen/Makefile
> @@ -54,6 +54,7 @@ obj-$(CONFIG_TOUCHSCREEN_PIXCIR)	+= pixcir_i2c_ts.o
>  obj-$(CONFIG_TOUCHSCREEN_S3C2410)	+= s3c2410_ts.o
>  obj-$(CONFIG_TOUCHSCREEN_ST1232)	+= st1232.o
>  obj-$(CONFIG_TOUCHSCREEN_STMPE)		+= stmpe-ts.o
> +obj-$(CONFIG_TOUCHSCREEN_SUN4I)		+= sun4i-ts.o
>  obj-$(CONFIG_TOUCHSCREEN_SUR40)		+= sur40.o
>  obj-$(CONFIG_TOUCHSCREEN_TI_AM335X_TSC)	+= ti_am335x_tsc.o
>  obj-$(CONFIG_TOUCHSCREEN_TNETV107X)	+= tnetv107x-ts.o
> diff --git a/drivers/input/touchscreen/sun4i-ts.c b/drivers/input/touchscreen/sun4i-ts.c
> new file mode 100644
> index 0000000..b3f01c0
> --- /dev/null
> +++ b/drivers/input/touchscreen/sun4i-ts.c
> @@ -0,0 +1,272 @@
> +/*
> + * sun4i-ts.c Allwinner sunxi resistive touchscreen controller driver

No file names please.

> + *
> + * Copyright (C) 2013 - 2014 Hans de Goede <hdegoede@redhat.com>
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License as published by
> + * the Free Software Foundation; either version 2 of the License, or
> + * (at your option) any later version.
> + *
> + * This program is distributed in the hope that it will be useful,
> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
> + * GNU General Public License for more details.
> + */
> +
> +/*
> + * The sun4i-ts controller is capable of detecting a second touch, but when a
> + * second touch is present then the accuracy becomes so bad the reported touch
> + * location is not useable.
> + *
> + * The original android driver contains some complicated heuristics using the
> + * aprox. distance between the 2 touches to see if the user is making a pinch
> + * open / close movement, and then reports emulated multi-touch events around
> + * the last touch coordinate (as the dual-touch coordinates are worthless).
> + *
> + * These kinds of heuristics are just asking for trouble (and don't belong
> + * in the kernel). So this driver offers straight forward, reliable single
> + * touch functionality only.
> + */
> +
> +#include <linux/delay.h>
> +#include <linux/err.h>
> +#include <linux/init.h>
> +#include <linux/input.h>
> +#include <linux/interrupt.h>
> +#include <linux/io.h>
> +#include <linux/module.h>
> +#include <linux/of_platform.h>
> +#include <linux/platform_device.h>
> +#include <linux/slab.h>
> +
> +#define TP_CTRL0		0x00
> +#define TP_CTRL1		0x04
> +#define TP_CTRL2		0x08
> +#define TP_CTRL3		0x0c
> +#define TP_INT_FIFOC		0x10
> +#define TP_INT_FIFOS		0x14
> +#define TP_TPR			0x18
> +#define TP_CDAT			0x1c
> +#define TEMP_DATA		0x20
> +#define TP_DATA			0x24
> +
> +/* TP_CTRL0 bits */
> +#define ADC_FIRST_DLY(x)	((x) << 24) /* 8 bits */
> +#define ADC_FIRST_DLY_MODE(x)	((x) << 23)
> +#define ADC_CLK_SEL(x)		((x) << 22)
> +#define ADC_CLK_DIV(x)		((x) << 20) /* 3 bits */
> +#define FS_DIV(x)		((x) << 16) /* 4 bits */
> +#define T_ACQ(x)		((x) << 0) /* 16 bits */
> +
> +/* TP_CTRL1 bits */
> +#define STYLUS_UP_DEBOUN(x)	((x) << 12) /* 8 bits */
> +#define STYLUS_UP_DEBOUN_EN(x)	((x) << 9)
> +#define TOUCH_PAN_CALI_EN(x)	((x) << 6)
> +#define TP_DUAL_EN(x)		((x) << 5)
> +#define TP_MODE_EN(x)		((x) << 4)
> +#define TP_ADC_SELECT(x)	((x) << 3)
> +#define ADC_CHAN_SELECT(x)	((x) << 0)  /* 3 bits */
> +
> +/* TP_CTRL2 bits */
> +#define TP_SENSITIVE_ADJUST(x)	((x) << 28) /* 4 bits */
> +#define TP_MODE_SELECT(x)	((x) << 26) /* 2 bits */
> +#define PRE_MEA_EN(x)		((x) << 24)
> +#define PRE_MEA_THRE_CNT(x)	((x) << 0) /* 24 bits */
> +
> +/* TP_CTRL3 bits */
> +#define FILTER_EN(x)		((x) << 2)
> +#define FILTER_TYPE(x)		((x) << 0)  /* 2 bits */
> +
> +/* TP_INT_FIFOC irq and fifo mask / control bits */
> +#define TEMP_IRQ_EN(x)		((x) << 18)
> +#define OVERRUN_IRQ_EN(x)	((x) << 17)
> +#define DATA_IRQ_EN(x)		((x) << 16)
> +#define TP_DATA_XY_CHANGE(x)	((x) << 13)
> +#define FIFO_TRIG(x)		((x) << 8)  /* 5 bits */
> +#define DATA_DRQ_EN(x)		((x) << 7)
> +#define FIFO_FLUSH(x)		((x) << 4)
> +#define TP_UP_IRQ_EN(x)		((x) << 1)
> +#define TP_DOWN_IRQ_EN(x)	((x) << 0)
> +
> +/* TP_INT_FIFOS irq and fifo status bits */
> +#define TEMP_DATA_PENDING	(1 << 18)
> +#define FIFO_OVERRUN_PENDING	(1 << 17)
> +#define FIFO_DATA_PENDING	(1 << 16)
> +#define TP_IDLE_FLG		(1 << 2)
> +#define TP_UP_PENDING		(1 << 1)
> +#define TP_DOWN_PENDING		(1 << 0)
> +
> +struct sun4i_ts_data {
> +	struct device *dev;
> +	void __iomem *base;
> +	struct input_dev *input;

bool?

> +	int ignore_fifo_data;
> +};
> +
> +static irqreturn_t sun4i_ts_irq(int irq, void *dev_id)
> +{
> +	struct sun4i_ts_data *ts = dev_id;
> +	u32 reg_val, x, y;
> +
> +	reg_val  = readl(ts->base + TP_INT_FIFOS);
> +
> +	if (reg_val & FIFO_DATA_PENDING) {
> +		x = readl(ts->base + TP_DATA);
> +		y = readl(ts->base + TP_DATA);
> +		/* The 1st location reported after an up event is unreliable */
> +		if (!ts->ignore_fifo_data) {
> +			input_report_abs(ts->input, ABS_X, x);
> +			input_report_abs(ts->input, ABS_Y, y);
> +			/*
> +			 * The hardware has a separate down status bit, but
> +			 * that gets set before we get the first location,
> +			 * resulting in reporting a click on the old location.
> +			 */
> +			input_report_key(ts->input, BTN_TOUCH, 1);
> +			input_sync(ts->input);
> +		} else
> +			ts->ignore_fifo_data = 0;

Please use braces either in none, or in both branches.

> +	}
> +
> +	if (reg_val & TP_UP_PENDING) {
> +		ts->ignore_fifo_data = 1;
> +		input_report_key(ts->input, BTN_TOUCH, 0);
> +		input_sync(ts->input);
> +	}
> +
> +	writel(reg_val, ts->base + TP_INT_FIFOS);
> +
> +	return IRQ_HANDLED;
> +}
> +
> +static int sun4i_ts_register_input(struct sun4i_ts_data *ts,
> +					     const char *name)
> +{
> +	int ret;
> +	struct input_dev *input;
> +
> +	input = devm_input_allocate_device(ts->dev);
> +	if (!input)
> +		return -ENOMEM;
> +
> +	input->name = name;
> +	input->phys = "sun4i_ts/input0";
> +	input->id.bustype = BUS_HOST;
> +	input->id.vendor = 0x0001;
> +	input->id.product = 0x0001;
> +	input->id.version = 0x0100;
> +	input->dev.parent = ts->dev;
> +	input->evbit[0] =  BIT(EV_SYN) | BIT(EV_KEY) | BIT(EV_ABS);
> +	set_bit(BTN_TOUCH, input->keybit);
> +	input_set_abs_params(input, ABS_X, 0, 4095, 0, 0);
> +	input_set_abs_params(input, ABS_Y, 0, 4095, 0, 0);
> +
> +	ret = input_register_device(input);
> +	if (ret)
> +		return ret;
> +
> +	ts->input = input;
> +	return 0;
> +}
> +
> +static int sun4i_ts_remove(struct platform_device *pdev)
> +{
> +	struct sun4i_ts_data *ts = platform_get_drvdata(pdev);
> +
> +	/* Deactivate all IRQs */
> +	writel(0, ts->base + TP_INT_FIFOC);

Should this be moved into close() method of input device?
 
> +	msleep(20);

Why do you need msleep here? Are you trying to ensure that interrupts
are not happening? In that case synchronize_irq() is better option I
think.

> +
> +	if (ts->input)
> +		input_unregister_device(ts->input);

Since you are using managed input device you do not need to call
input_unregister_device() explicitly.

> +
> +	kfree(ts);
> +
> +	return 0;
> +}
> +
> +static int sun4i_ts_probe(struct platform_device *pdev)
> +{
> +	struct sun4i_ts_data *ts;
> +	int ret = -ENOMEM;
> +
> +	ts = kzalloc(sizeof(struct sun4i_ts_data), GFP_KERNEL);
> +	if (!ts)
> +		return -ENOMEM;

I believe someone already mentioned devm_kzalloc()...

> +
> +	platform_set_drvdata(pdev, ts);
> +
> +	ts->dev = &pdev->dev;
> +	ts->base = devm_ioremap_resource(&pdev->dev,
> +			      platform_get_resource(pdev, IORESOURCE_MEM, 0));
> +	if (IS_ERR(ts->base)) {
> +		ret = PTR_ERR(ts->base);
> +		goto error;
> +	}
> +
> +	ret = devm_request_irq(&pdev->dev, platform_get_irq(pdev, 0),
> +			       sun4i_ts_irq, 0, "sun4i-ts", ts);
> +	if (ret)
> +		goto error;
> +

Are we 1000% sure that the device is quiesced here and we will not get a
stray interrupt? Even if we are sure I'd still rather allocate input
device earlier, together with ts structure.

> +	ret = sun4i_ts_register_input(ts, pdev->name);
> +	if (ret)
> +		goto error;
> +
> +	/*
> +	 * Select HOSC clk, clkin = clk / 6, adc samplefreq = clkin / 8192,
> +	 * t_acq = clkin / (16 * 64)
> +	 */
> +	writel(ADC_CLK_SEL(0) | ADC_CLK_DIV(2) | FS_DIV(7) | T_ACQ(63),
> +	       ts->base + TP_CTRL0);
> +
> +	/*
> +	 * sensitive_adjust = 15 : max, which is not all that sensitive,
> +	 * tp_mode = 0 : only x and y coordinates, as we don't use dual touch
> +	 */
> +	writel(TP_SENSITIVE_ADJUST(15) | TP_MODE_SELECT(0),
> +	       ts->base + TP_CTRL2);
> +
> +	/* Enable median filter, type 1 : 5/3 */
> +	writel(FILTER_EN(1) | FILTER_TYPE(1), ts->base + TP_CTRL3);
> +
> +	/* Flush fifo, set trig level to 1, enable data and pen up irqs */
> +	writel(DATA_IRQ_EN(1) | FIFO_TRIG(1) | FIFO_FLUSH(1) | TP_UP_IRQ_EN(1),
> +	       ts->base + TP_INT_FIFOC);
> +
> +	/*
> +	 * Set stylus up debounce to aprox 10 ms, enable debounce, and
> +	 * finally enable tp mode.
> +	 */
> +	writel(STYLUS_UP_DEBOUN(5) | STYLUS_UP_DEBOUN_EN(1) | TP_MODE_EN(1),
> +	       ts->base + TP_CTRL1);

Should all of some of this be moved into open() method for your input
device?

> +
> +	return 0;
> +
> +error:
> +	sun4i_ts_remove(pdev);
> +	return ret;
> +}
> +
> +static const struct of_device_id sun4i_ts_of_match[] = {
> +	{ .compatible = "allwinner,sun4i-ts", },
> +	{ /* sentinel */ }
> +};
> +MODULE_DEVICE_TABLE(of, sun4i_ts_of_match);
> +
> +static struct platform_driver sun4i_ts_driver = {
> +	.driver = {
> +		.owner	= THIS_MODULE,
> +		.name	= "sun4i-ts",
> +		.of_match_table = of_match_ptr(sun4i_ts_of_match),
> +	},
> +	.probe	= sun4i_ts_probe,
> +	.remove	= sun4i_ts_remove,
> +};
> +
> +module_platform_driver(sun4i_ts_driver);
> +
> +MODULE_DESCRIPTION("Allwinner sun4i resistive touchscreen controller driver");
> +MODULE_AUTHOR("Hans de Goede <hdegoede@redhat.com>");
> +MODULE_LICENSE("GPL");
> -- 
> 1.8.4.2
> 

Thanks.

-- 
Dmitry