Re: [PATCH] Input: qt1050 - add Microchip AT42QT1050 support

[Marco Felsch <m.felsch@pengutronix.de>]

Hi Dmitry,

On 18-10-17 17:39, Dmitry Torokhov wrote:
> On Thu, Oct 18, 2018 at 01:31:53AM +0200, Marco Felsch wrote:
> > Hi Dmitry,
> > 
> > thanks for your review.
> > 
> > On 18-10-15 20:44, Dmitry Torokhov wrote:
> > > Hi Marco,
> > > 
> > > On Mon, Sep 24, 2018 at 05:13:30PM +0200, Marco Felsch wrote:
> > > > Add initial support for the AT42QT1050 (QT1050) device. The device
> > > > supports up to five input keys, dependent on the mode. Since it adds only
> > > > the initial support the "1 to 4 keys plus Guard Channel" mode isn't
> > > > support.
> > > > 
> > > > Signed-off-by: Marco Felsch <m.felsch@pengutronix.de>
> > > > ---
> > > >  .../bindings/input/microchip,qt1050.txt       |  54 ++
> > > >  drivers/input/keyboard/Kconfig                |  11 +
> > > >  drivers/input/keyboard/Makefile               |   1 +
> > > >  drivers/input/keyboard/qt1050.c               | 589 ++++++++++++++++++
> > > >  4 files changed, 655 insertions(+)
> > > >  create mode 100644 Documentation/devicetree/bindings/input/microchip,qt1050.txt
> > > >  create mode 100644 drivers/input/keyboard/qt1050.c
> > > > 
> > > > diff --git a/Documentation/devicetree/bindings/input/microchip,qt1050.txt b/Documentation/devicetree/bindings/input/microchip,qt1050.txt
> > > > new file mode 100644
> > > > index 000000000000..d63e286f6526
> > > > --- /dev/null
> > > > +++ b/Documentation/devicetree/bindings/input/microchip,qt1050.txt
> > > > @@ -0,0 +1,54 @@
> > > > +Microchip AT42QT1050 Five-channel Touch Sensor IC
> > > > +
> > > > +The AT42QT1050 (QT1050) is a QTouchADC sensor driver. The device can sense from
> > > > +one to five keys, dependent on mode. The QT1050 includes all signal processing
> > > > +functions necessary to provide stable sensing under a wide variety of changing
> > > > +conditions, and the outputs are fully debounced.
> > > > +
> > > > +The touchkey device node should be placed inside an I2C bus node.
> > > > +
> > > > +Required properties:
> > > > +- compatible: Must be "microchip,qt1050"
> > > > +- reg: The I2C address of the touchkeys
> > > > +- interrupts: The sink for the touchpad's IRQ output,
> > > > +  see ../interrupt-controller/interrupts.txt
> > > > +- linux,keycodes: Specifies an array of numeric keycode values to be used for
> > > > +  reporting button presses. The array can contain up to 5 entries. Array index
> > > > +  0 correspond to key 0 and so on. If the keys aren't continuous the
> > > > +  KEY_RESERVED must be used. Keys marked as KEY_RESERVED or not specified will
> > > > +  be disabled.
> > > > +
> > > > +Optional properties:
> > > > +- pre-charge-time: Specifies an array of precharge times in ns for each touch
> > > > +  pad. The value for each pad depend on the hardware layouts. If not specified
> > > > +  or invalid values are specified the default value is taken.
> > > > +  Valid value range [ns]: 0 - 637500; values must be a multiple of 2500;
> > > > +  default is 0.
> > > > +- touchscreen-average-samples: Please see ../input/touchscreen/touchscreen.txt
> > > > +  for more information. Unlike the general binding, this is an array to specify
> > > > +  the samples for each pad. If not specified or invalid values are specified
> > > > +  the default value is taken.
> > > > +  Valid values: 1, 4, 16, 64, 256, 1024, 4096, 16384; default is 1.
> > > > +- touchscreen-pre-scaling: Please see ../input/touchscreen/touchscreen.txt for
> > > > +  more information. Unlike the general binding, this is an array to specify the
> > > > +  scaling factor for each pad. If not specified or invalid values are specified
> > > > +  the default value is taken.
> > > > +  Valid values: 1, 2, 4, 8, 16, 32, 64, 128; default is 1.
> > > > +- touchscreen-fuzz-pressure: Please see ../input/touchscreen/touchscreen.txt for
> > > > +  more information. Unlike the general binding, this is an array to specify the
> > > > +  noise (threshold) value for each pad. If not specified or invalid values are
> > > > +  specified the default value is taken.
> > > 
> > > I am confused why we refer to touchscreen bindings here... Yes, the
> > > device is a capacitive touch sensor, but it it not a touchscreen
> > > controller. I think referring to generic touchscreen binding is
> > > confusing. Especially since they even do not map to the generic binding
> > > (list vs scalar value).
> > 
> > Yes I'm deliberated about that too. I'm with you it isn't touchscreen
> > controller and you're right the driver accepts arrays, but the meaning
> > of the bindings map 1:1
> 
> Not quite. For example, in input fuzz is used to "smooth out" the
> readings (see input_defuzz_abs_event) and not a threshhold (which it
> seems to be from the name in the driver). And I have no idea what
> "touchscreen-pre-scaling" is as it is not in my tree...
> 
> > and I wouldn't introduce new vendor-specific
> > bindings.
> 
> I think vendor-neutral bindings only make sense if the meaning and the
> type of data (and devices) are the same. I.e. if we have and IIO
> pressure meter device it should not be using touchscreen-fuzz-pressure
> even though device is dealing with pressure.

Okay I will change that to device specific bindings.

> > Rob what do you think about that? Should I replace it by:
> > 
> > s/touchscreen-/microchip,touch-/
> > 
> > > > +  Valid value range: 0 - 255; default is 20.
> > > > +
> > > > +Example:
> > > > +QT1050 with 3 non continuous key, key3 and key5 are disabled.
> > > > +
> > > > +touchkeys@41 {
> > > > +	compatible = "microchip,qt1050";
> > > > +	reg = <0x41>;
> > > > +	interrupt-parent = <&gpio0>;
> > > > +	interrupts = <17 IRQ_TYPE_EDGE_FALLING>;
> > > > +	linux,keycodes = <KEY_UP>, <KEY_RIGHT>, <KEY_RESERVED>, <KEY_DOWN>;
> > > > +	touchscreen-average-samples = <64>, <64>, <64>, <256>;
> > > > +	touchscreen-pre-scaling = <16>, <8>, <16>, <16>;
> > > > +};
> > > > diff --git a/drivers/input/keyboard/Kconfig b/drivers/input/keyboard/Kconfig
> > > > index 4713957b0cbb..08aba5e7cd93 100644
> > > > --- a/drivers/input/keyboard/Kconfig
> > > > +++ b/drivers/input/keyboard/Kconfig
> > > > @@ -137,6 +137,17 @@ config KEYBOARD_ATKBD_RDI_KEYCODES
> > > >  	  right-hand column will be interpreted as the key shown in the
> > > >  	  left-hand column.
> > > >  
> > > > +config KEYBOARD_QT1050
> > > > +	tristate "Microchip AT42QT1050 Touch Sensor Chip"
> > > > +	depends on I2C
> > > > +	select REGMAP_I2C
> > > > +	help
> > > > +	  Say Y here if you want to use Microchip AT42QT1050 QTouch
> > > > +	  Sensor chip as input device.
> > > > +
> > > > +	  To compile this driver as a module, choose M here:
> > > > +	  the module will be called qt1050
> > > > +
> > > >  config KEYBOARD_QT1070
> > > >         tristate "Atmel AT42QT1070 Touch Sensor Chip"
> > > >         depends on I2C
> > > > diff --git a/drivers/input/keyboard/Makefile b/drivers/input/keyboard/Makefile
> > > > index 182e92985dbf..f0291ca39f62 100644
> > > > --- a/drivers/input/keyboard/Makefile
> > > > +++ b/drivers/input/keyboard/Makefile
> > > > @@ -50,6 +50,7 @@ obj-$(CONFIG_KEYBOARD_OPENCORES)	+= opencores-kbd.o
> > > >  obj-$(CONFIG_KEYBOARD_PMIC8XXX)		+= pmic8xxx-keypad.o
> > > >  obj-$(CONFIG_KEYBOARD_PXA27x)		+= pxa27x_keypad.o
> > > >  obj-$(CONFIG_KEYBOARD_PXA930_ROTARY)	+= pxa930_rotary.o
> > > > +obj-$(CONFIG_KEYBOARD_QT1050)           += qt1050.o
> > > >  obj-$(CONFIG_KEYBOARD_QT1070)           += qt1070.o
> > > >  obj-$(CONFIG_KEYBOARD_QT2160)		+= qt2160.o
> > > >  obj-$(CONFIG_KEYBOARD_SAMSUNG)		+= samsung-keypad.o
> > > > diff --git a/drivers/input/keyboard/qt1050.c b/drivers/input/keyboard/qt1050.c
> > > > new file mode 100644
> > > > index 000000000000..80415586955d
> > > > --- /dev/null
> > > > +++ b/drivers/input/keyboard/qt1050.c
> > > > @@ -0,0 +1,589 @@
> > > > +// SPDX-License-Identifier: GPL-2.0
> > > > +/*
> > > > + *  Microchip AT42QT1050 QTouch Sensor Controller
> > > > + *
> > > > + *  Authors: Marco Felsch <kernel@pengutronix.de>
> > > > + *
> > > > + *  Base on AT42QT1070 driver by:
> > > > + *  Bo Shen <voice.shen@atmel.com>
> > > > + *  Copyright (C) 2011 Atmel
> > > > + */
> > > > +
> > > > +#include <linux/delay.h>
> > > > +#include <linux/i2c.h>
> > > > +#include <linux/input.h>
> > > > +#include <linux/interrupt.h>
> > > > +#include <linux/kernel.h>
> > > > +#include <linux/log2.h>
> > > > +#include <linux/module.h>
> > > > +#include <linux/of.h>
> > > > +#include <linux/regmap.h>
> > > > +
> > > > +/* Chip ID */
> > > > +#define QT1050_CHIP_ID		0x00
> > > > +#define QT1050_CHIP_ID_VER	0x46
> > > > +
> > > > +/* Firmware version */
> > > > +#define QT1050_FW_VERSION	0x01
> > > > +
> > > > +/* Detection status */
> > > > +#define QT1050_DET_STATUS	0x02
> > > > +
> > > > +/* Key status */
> > > > +#define QT1050_KEY_STATUS	0x03
> > > > +
> > > > +/* Key Signals */
> > > > +#define QT1050_KEY_SIGNAL_0_MSB	0x06
> > > > +#define QT1050_KEY_SIGNAL_0_LSB	0x07
> > > > +#define QT1050_KEY_SIGNAL_1_MSB	0x08
> > > > +#define QT1050_KEY_SIGNAL_1_LSB	0x09
> > > > +#define QT1050_KEY_SIGNAL_2_MSB	0x0c
> > > > +#define QT1050_KEY_SIGNAL_2_LSB	0x0d
> > > > +#define QT1050_KEY_SIGNAL_3_MSB	0x0e
> > > > +#define QT1050_KEY_SIGNAL_3_LSB	0x0f
> > > > +#define QT1050_KEY_SIGNAL_4_MSB	0x10
> > > > +#define QT1050_KEY_SIGNAL_4_LSB	0x11
> > > > +
> > > > +/* Reference data */
> > > > +#define QT1050_REF_DATA_0_MSB	0x14
> > > > +#define QT1050_REF_DATA_0_LSB	0x15
> > > > +#define QT1050_REF_DATA_1_MSB	0x16
> > > > +#define QT1050_REF_DATA_1_LSB	0x17
> > > > +#define QT1050_REF_DATA_2_MSB	0x1a
> > > > +#define QT1050_REF_DATA_2_LSB	0x1b
> > > > +#define QT1050_REF_DATA_3_MSB	0x1c
> > > > +#define QT1050_REF_DATA_3_LSB	0x1d
> > > > +#define QT1050_REF_DATA_4_MSB	0x1e
> > > > +#define QT1050_REF_DATA_4_LSB	0x1f
> > > > +
> > > > +/* Negative threshold level */
> > > > +#define QT1050_NTHR_0		0x21
> > > > +#define QT1050_NTHR_1		0x22
> > > > +#define QT1050_NTHR_2		0x24
> > > > +#define QT1050_NTHR_3		0x25
> > > > +#define QT1050_NTHR_4		0x26
> > > > +
> > > > +/* Pulse / Scale  */
> > > > +#define QT1050_PULSE_SCALE_0	0x28
> > > > +#define QT1050_PULSE_SCALE_1	0x29
> > > > +#define QT1050_PULSE_SCALE_2	0x2b
> > > > +#define QT1050_PULSE_SCALE_3	0x2c
> > > > +#define QT1050_PULSE_SCALE_4	0x2d
> > > > +
> > > > +/* Detection integrator counter / AKS */
> > > > +#define QT1050_DI_AKS_0		0x2f
> > > > +#define QT1050_DI_AKS_1		0x30
> > > > +#define QT1050_DI_AKS_2		0x32
> > > > +#define QT1050_DI_AKS_3		0x33
> > > > +#define QT1050_DI_AKS_4		0x34
> > > > +
> > > > +/* Charge Share Delay */
> > > > +#define QT1050_CSD_0		0x36
> > > > +#define QT1050_CSD_1		0x37
> > > > +#define QT1050_CSD_2		0x39
> > > > +#define QT1050_CSD_3		0x3a
> > > > +#define QT1050_CSD_4		0x3b
> > > > +
> > > > +/* Low Power Mode */
> > > > +#define QT1050_LPMODE		0x3d
> > > > +
> > > > +/* Calibration and Reset */
> > > > +#define QT1050_RES_CAL		0x3f
> > > > +#define QT1050_RES_CAL_RESET		BIT(7)
> > > > +#define QT1050_RES_CAL_CALIBRATE	BIT(1)
> > > > +
> > > > +#define QT1050_MAX_KEYS		5
> > > > +#define QT1050_RESET_TIME	255
> > > > +
> > > > +struct qt1050_key {
> > > > +	u32 charge_delay;
> > > > +	u32 thr_cnt;
> > > > +	u32 samples;
> > > > +	u32 scale;
> > > > +	u16 keycode;
> > > > +};
> > > > +
> > > > +struct qt1050_priv {
> > > > +	struct i2c_client	*client;
> > > > +	struct input_dev	*input;
> > > > +	struct regmap		*regmap;
> > > > +	struct qt1050_key	keys[QT1050_MAX_KEYS];
> > > > +	unsigned short		keycodes[QT1050_MAX_KEYS];
> > > > +	u8			last_keys;
> > > > +};
> > > > +
> > > > +static bool qt1050_volatile_reg(struct device *dev, unsigned int reg)
> > > > +{
> > > > +	switch (reg) {
> > > > +	case QT1050_DET_STATUS:
> > > > +	case QT1050_KEY_STATUS:
> > > > +	case QT1050_KEY_SIGNAL_0_MSB:
> > > > +	case QT1050_KEY_SIGNAL_0_LSB:
> > > > +	case QT1050_KEY_SIGNAL_1_MSB:
> > > > +	case QT1050_KEY_SIGNAL_1_LSB:
> > > > +	case QT1050_KEY_SIGNAL_2_MSB:
> > > > +	case QT1050_KEY_SIGNAL_2_LSB:
> > > > +	case QT1050_KEY_SIGNAL_3_MSB:
> > > > +	case QT1050_KEY_SIGNAL_3_LSB:
> > > > +	case QT1050_KEY_SIGNAL_4_MSB:
> > > > +	case QT1050_KEY_SIGNAL_4_LSB:
> > > > +		return true;
> > > > +	default:
> > > > +		return false;
> > > > +	}
> > > > +}
> > > > +
> > > > +static const struct regmap_range qt1050_readable_ranges[] = {
> > > > +	regmap_reg_range(QT1050_CHIP_ID, QT1050_KEY_STATUS),
> > > > +	regmap_reg_range(QT1050_KEY_SIGNAL_0_MSB, QT1050_KEY_SIGNAL_1_LSB),
> > > > +	regmap_reg_range(QT1050_KEY_SIGNAL_2_MSB, QT1050_KEY_SIGNAL_4_LSB),
> > > > +	regmap_reg_range(QT1050_REF_DATA_0_MSB, QT1050_REF_DATA_1_LSB),
> > > > +	regmap_reg_range(QT1050_REF_DATA_2_MSB, QT1050_REF_DATA_4_LSB),
> > > > +	regmap_reg_range(QT1050_NTHR_0, QT1050_NTHR_1),
> > > > +	regmap_reg_range(QT1050_NTHR_2, QT1050_NTHR_4),
> > > > +	regmap_reg_range(QT1050_PULSE_SCALE_0, QT1050_PULSE_SCALE_1),
> > > > +	regmap_reg_range(QT1050_PULSE_SCALE_2, QT1050_PULSE_SCALE_4),
> > > > +	regmap_reg_range(QT1050_DI_AKS_0, QT1050_DI_AKS_1),
> > > > +	regmap_reg_range(QT1050_DI_AKS_2, QT1050_DI_AKS_4),
> > > > +	regmap_reg_range(QT1050_CSD_0, QT1050_CSD_1),
> > > > +	regmap_reg_range(QT1050_CSD_2, QT1050_RES_CAL),
> > > > +};
> > > > +
> > > > +static const struct regmap_access_table qt1050_readable_table = {
> > > > +	.yes_ranges = qt1050_readable_ranges,
> > > > +	.n_yes_ranges = ARRAY_SIZE(qt1050_readable_ranges),
> > > > +};
> > > > +
> > > > +static const struct regmap_range qt1050_writeable_ranges[] = {
> > > > +	regmap_reg_range(QT1050_NTHR_0, QT1050_NTHR_1),
> > > > +	regmap_reg_range(QT1050_NTHR_2, QT1050_NTHR_4),
> > > > +	regmap_reg_range(QT1050_PULSE_SCALE_0, QT1050_PULSE_SCALE_1),
> > > > +	regmap_reg_range(QT1050_PULSE_SCALE_2, QT1050_PULSE_SCALE_4),
> > > > +	regmap_reg_range(QT1050_DI_AKS_0, QT1050_DI_AKS_1),
> > > > +	regmap_reg_range(QT1050_DI_AKS_2, QT1050_DI_AKS_4),
> > > > +	regmap_reg_range(QT1050_CSD_0, QT1050_CSD_1),
> > > > +	regmap_reg_range(QT1050_CSD_2, QT1050_RES_CAL),
> > > > +};
> > > > +
> > > > +static const struct regmap_access_table qt1050_writeable_table = {
> > > > +	.yes_ranges = qt1050_writeable_ranges,
> > > > +	.n_yes_ranges = ARRAY_SIZE(qt1050_writeable_ranges),
> > > > +};
> > > > +
> > > > +static struct regmap_config qt1050_regmap_config = {
> > > > +	.reg_bits = 8,
> > > > +	.val_bits = 8,
> > > > +	.max_register = QT1050_RES_CAL,
> > > > +
> > > > +	.cache_type = REGCACHE_RBTREE,
> > > > +
> > > > +	.wr_table = &qt1050_writeable_table,
> > > > +	.rd_table = &qt1050_readable_table,
> > > > +	.volatile_reg = qt1050_volatile_reg,
> > > > +};
> > > > +
> > > > +static bool qt1050_identify(struct qt1050_priv *ts)
> > > > +{
> > > > +	unsigned int val;
> > > > +
> > > > +	/* Read Chip ID */
> > > > +	regmap_read(ts->regmap, QT1050_CHIP_ID, &val);
> > > > +	if (val != QT1050_CHIP_ID_VER) {
> > > > +		dev_err(&ts->client->dev, "ID %d not supported\n", val);
> > > > +		return false;
> > > > +	}
> > > > +
> > > > +	/* Read firmware version */
> > > > +	regmap_read(ts->regmap, QT1050_FW_VERSION, &val);
> > > > +	if (val < 0) {
> > > > +		dev_err(&ts->client->dev, "could not read the firmware version\n");
> > > > +		return false;
> > > > +	}
> > > > +
> > > > +	dev_info(&ts->client->dev, "AT42QT1050 firmware version %1d.%1d\n",
> > > > +		 val >> 4, val & 0xf);
> > > > +
> > > > +	return true;
> > > > +}
> > > > +
> > > > +static irqreturn_t qt1050_irq_threaded(int irq, void *dev_id)
> > > > +{
> > > > +	struct qt1050_priv *ts = dev_id;
> > > > +	struct input_dev *input = ts->input;
> > > > +	unsigned long new_keys, changed;
> > > > +	unsigned int val;
> > > > +	int i, err;
> > > > +
> > > > +	/* Read the detected status register, thus clearing interrupt */
> > > > +	err = regmap_read(ts->regmap, QT1050_DET_STATUS, &val);
> > > > +	if (err) {
> > > > +		dev_err(&ts->client->dev, "Fail to read detection status: %d\n",
> > > > +			err);
> > > > +		return IRQ_NONE;
> > > > +	}
> > > > +
> > > > +	/* Read which key changed, keys are not continuous */
> > > > +	err = regmap_read(ts->regmap, QT1050_KEY_STATUS, &val);
> > > > +	if (err) {
> > > > +		dev_err(&ts->client->dev,
> > > > +			"Fail to determine the key status: %d\n", err);
> > > > +		return IRQ_NONE;
> > > > +	}
> > > > +	new_keys = (val & 0x70) >> 2 | (val & 0x6) >> 1;
> > > > +	changed = ts->last_keys ^ new_keys;
> > > > +
> > > > +	for_each_set_bit(i, &changed, 8) {
> > > > +		input_report_key(input, ts->keycodes[i],
> > > > +				 test_bit(i, &new_keys));
> > > > +	}
> > > > +
> > > > +	ts->last_keys = new_keys;
> > > > +	input_sync(input);
> > > > +
> > > > +	return IRQ_HANDLED;
> > > > +}
> > > > +
> > > > +static int qt1050_disable_key(struct regmap *map, int number)
> > > > +{
> > > > +	unsigned int reg;
> > > > +
> > > > +	switch (number) {
> > > > +	case 0:
> > > > +		reg = QT1050_DI_AKS_0;
> > > > +		break;
> > > > +	case 1:
> > > > +		reg = QT1050_DI_AKS_1;
> > > > +		break;
> > > > +	case 2:
> > > > +		reg = QT1050_DI_AKS_2;
> > > > +		break;
> > > > +	case 3:
> > > > +		reg = QT1050_DI_AKS_3;
> > > > +		break;
> > > > +	case 4:
> > > > +		reg = QT1050_DI_AKS_4;
> > > > +		break;
> 
> I wonder if there is any value in doing
> 
> 	reg = QT1050_DI_AKS_0 + i + (i > 2);
> 
> and similarly for other registers.

Yes there is a gap in the register map and your approach is smart, but I
find my less error prone (i.e. it should be (i > 1)) and easier to read
it. Anyway I can change this if you find it better.

> > > > +	}
> > > > +
> > > > +	return regmap_update_bits(map, reg, 0xfc, 0x00);
> > > > +}
> > > > +
> > > > +#ifdef CONFIG_OF
> > > > +static int qt1050_set_dt_data(struct qt1050_priv *ts)
> > > > +{
> > > > +	struct regmap *map = ts->regmap;
> > > > +	struct qt1050_key *k;
> > > > +	int i, err;
> > > > +	unsigned int pulsc_reg, csd_reg, nthr_reg;
> > > > +
> > > > +	for (i = 0; i < QT1050_MAX_KEYS; i++) {
> > > > +		k = &ts->keys[i];
> > > > +		/* disable all keys which are marked as KEY_RESERVED */
> > > > +		if (k->keycode == KEY_RESERVED) {
> > > > +			err = qt1050_disable_key(map, i);
> > > > +			if (err)
> > > > +				return err;
> > > > +			continue;
> > > > +		}
> > > > +
> > > > +		switch (i) {
> > > > +		case 0:
> > > > +			pulsc_reg = QT1050_PULSE_SCALE_0;
> > > > +			csd_reg = QT1050_CSD_0;
> > > > +			nthr_reg = QT1050_NTHR_0;
> > > > +			break;
> > > > +		case 1:
> > > > +			pulsc_reg = QT1050_PULSE_SCALE_1;
> > > > +			csd_reg = QT1050_CSD_1;
> > > > +			nthr_reg = QT1050_NTHR_1;
> > > > +			break;
> > > > +		case 2:
> > > > +			pulsc_reg = QT1050_PULSE_SCALE_1;
> 
> Should it be QT1050_PULSE_SCALE_2?

Yes, sorry my mistake.

> > > > +			csd_reg = QT1050_CSD_2;
> > > > +			nthr_reg = QT1050_NTHR_2;
> > > > +			break;
> > > > +		case 3:
> > > > +			pulsc_reg = QT1050_PULSE_SCALE_3;
> > > > +			csd_reg = QT1050_CSD_3;
> > > > +			nthr_reg = QT1050_NTHR_3;
> > > > +			break;
> > > > +		case 4:
> > > > +			pulsc_reg = QT1050_PULSE_SCALE_4;
> > > > +			csd_reg = QT1050_CSD_4;
> > > > +			nthr_reg = QT1050_NTHR_4;
> > > > +			break;
> > > > +		}
> > > > +
> > > > +		err = regmap_write(map, pulsc_reg,
> > > > +				   (k->samples << 4) | (k->scale));
> > > > +		if (err)
> > > > +			return err;
> > > > +		err = regmap_write(map, csd_reg, k->charge_delay);
> > > > +		if (err)
> > > > +			return err;
> > > > +		err = regmap_write(map, nthr_reg, k->thr_cnt);
> > > > +		if (err)
> > > > +			return err;
> > > > +	}
> > > > +
> > > > +	return 0;
> > > > +}
> > > > +
> > > > +static int qt1050_parse_dt(struct qt1050_priv *ts)
> > > > +{
> > > > +	struct device *dev = &ts->client->dev;
> > > > +	struct device_node *node = dev->of_node;
> > > > +	int ret, i, n_keys;
> > > > +	u32 tmp[QT1050_MAX_KEYS];
> > > > +
> > > > +	ret = of_property_read_variable_u32_array(node, "linux,keycodes",
> > > > +						  &tmp[0], 1,
> > > > +						  QT1050_MAX_KEYS);
> > > > +
> > > > +	/*
> > > > +	 * remaining keys are mapped to KEY_RESERVED in case of
> > > > +	 * n_keys < QT1050_MAX_KEYS
> > > > +	 */
> > > > +	n_keys = ret;
> > > > +	for (i = 0; i < n_keys; i++) {
> > > > +		if (tmp[i] >= KEY_MAX) {
> > > > +			dev_err(dev, "wrong keycode 0x%x\n", tmp[i]);
> > > > +			return -EINVAL;
> > > > +		}
> > > > +		ts->keys[i].keycode = (u16)tmp[i];
> > > > +	}
> > > > +
> > > > +	ret = of_property_read_variable_u32_array(node, "pre-charge-time",
> > > > +						  &tmp[0], 1, QT1050_MAX_KEYS);
> > > > +	if (!IS_ERR_VALUE(ret)) {
> > > > +		for (i = 0; i < QT1050_MAX_KEYS; i++) {
> > > > +			if (i < n_keys && (tmp[i] % 2500 == 0))
> > > > +				ts->keys[i].charge_delay = tmp[i] / 2500;
> > > > +			else
> > > > +				ts->keys[i].charge_delay = 0;
> > > > +		}
> > > > +	}
> > > > +
> > > > +	ret = of_property_read_variable_u32_array(node,
> > > > +						  "touchscreen-average-samples",
> > > > +						  &tmp[0], 1, QT1050_MAX_KEYS);
> > > > +	if (!IS_ERR_VALUE(ret)) {
> > > > +		for (i = 0; i < QT1050_MAX_KEYS; i++) {
> > > > +			if (i < n_keys && is_power_of_2(tmp[i]))
> > > > +				ts->keys[i].samples = ilog2(tmp[i]);
> > > > +			else
> > > > +				ts->keys[i].samples = 0;
> > > > +		}
> > > > +	}
> > > > +
> > > > +	ret = of_property_read_variable_u32_array(node,
> > > > +						  "touchscreen-pre-scaling",
> > > > +						  &tmp[0], 1, QT1050_MAX_KEYS);
> > > > +	if (!IS_ERR_VALUE(ret)) {
> > > > +		for (i = 0; i < QT1050_MAX_KEYS; i++) {
> > > > +			if (i < n_keys && is_power_of_2(tmp[i]))
> > > > +				ts->keys[i].scale = ilog2(tmp[i]);
> > > > +			else
> > > > +				ts->keys[i].scale = 0;
> > > > +		}
> > > > +	}
> > > > +
> > > > +	ret = of_property_read_variable_u32_array(node,
> > > > +						  "touchscreen-fuzz-pressure",
> > > > +						  &tmp[0], 1, QT1050_MAX_KEYS);
> > > > +	if (!IS_ERR_VALUE(ret))
> > > > +		for (i = 0; i < QT1050_MAX_KEYS; i++)
> > > > +			ts->keys[i].thr_cnt = i < n_keys ? tmp[i] : 20;
> > > > +
> > > > +	return 0;
> > > > +}
> > > > +#endif
> > > > +
> > > > +static int qt1050_probe(struct i2c_client *client,
> > > > +				const struct i2c_device_id *id)
> > > > +{
> > > > +	struct qt1050_priv *ts;
> > > > +	struct input_dev *input;
> > > > +	struct device *dev = &client->dev;
> > > > +	struct regmap *map;
> > > > +	unsigned int status;
> > > > +	int i;
> > > > +	int err;
> > > > +
> > > > +	/* Check basic functionality */
> > > > +	err = i2c_check_functionality(client->adapter, I2C_FUNC_SMBUS_BYTE);
> > > > +	if (!err) {
> > > > +		dev_err(&client->dev, "%s adapter not supported\n",
> > > > +			dev_driver_string(&client->adapter->dev));
> > > > +		return -ENODEV;
> > > > +	}
> > > > +
> > > > +	if (!client->irq) {
> > > > +		dev_err(dev, "assign a irq line to this device\n");
> > > > +		return -EINVAL;
> > > > +	}
> > > > +
> > > > +	ts = devm_kzalloc(dev, sizeof(*ts), GFP_KERNEL);
> > > > +	input = devm_input_allocate_device(dev);
> > > > +	if (!ts || !input) {
> > > > +		dev_err(dev, "insufficient memory\n");
> > > > +		return -ENOMEM;
> > > > +	}
> > > > +
> > > > +	map = devm_regmap_init_i2c(client, &qt1050_regmap_config);
> > > > +	if (IS_ERR(map))
> > > > +		return PTR_ERR(map);
> > > > +
> > > > +	ts->client = client;
> > > > +	ts->input = input;
> > > > +	ts->regmap = map;
> > > > +
> > > > +	i2c_set_clientdata(client, ts);
> > > > +
> > > > +	/* Identify the qt1050 chip */
> > > > +	if (!qt1050_identify(ts))
> > > > +		return -ENODEV;
> > > > +
> > > > +	if (IS_ENABLED(CONFIG_OF)) {
> > > > +		err = qt1050_parse_dt(ts);
> > > > +		if (err) {
> > > > +			dev_err(dev, "Failed to parse dt: %d\n", err);
> > > > +			return err;
> > > > +		}
> > > > +	} else {
> > > > +		/* init each key with a valid code */
> > > > +		for (i = 0; i < QT1050_MAX_KEYS; i++)
> > > > +			ts->keys[i].keycode = KEY_1 + i;
> > > > +	}
> > > 
> > > I'd rather we used generic device properties (i.e.
> > > device_property_read_xxx() instead of of_property_read_xxx()) and did
> > > not provide this fallback.
> > 
> > I'm with you, but I wanted to use the of_property_read_variable_*()
> > helpers, since all properties can distinguish in their array size.
> > Sure I can add a helper to reimplement that localy using the 
> > device_property_read_xxx() functions. IMHO this will be a later on
> > feature, if the acpi guys needs this features too. Is that okay?
> 
> Well, that is an argument for adding proper
> device_property_read_variable_*(). However, after lookign at the binding
> again, I wonder if you should not describe this as sub-nodes:

A device_property_read_variable_*() would be nice.

> 
> 	touchkeys@41 {
> 		...
> 		up@0 {
> 			reg = <0>;
> 			linux,code = <KEY_UP>;
> 			average-samples = <64>;
> 			pre-scaling = <16>;
> 			pressure-threshold = <...>;
> 		};
> 
> 		right@1 {
> 			reg = <1>;
> 			linux,code = <KEY_RIGHT>;
> 			average-samples = <64>;
> 			pre-scaling = <8>;
> 			pressure-threshold = <2>;
> 		};
> 		...
> 	};
> 
> and then use device_for_each_child_node() to parse it.

That's a good approach, thanks. I wanted to be similar with the other
input bindings, which uses arrays for linux,code and scalar values for
other properties. Since the qt1050 can configure each pad differently
I used only arrays. Is it good to change the layout only for one deivce?
Maybe it would better to implement the device_property_read_variable_*()
helper.

> Thanks.
> 

Regards,
Marco