Subject: [PATCH v8 6/8] input: touchscreen: imx25 tcq driver

From: [email-masked] (Dmitry Torokhov)
Date: Tue, 17 Nov 2015 10:17:20 -0800

On Mon, Nov 16, 2015 at 01:01:07PM +0100, Markus Pargmann wrote:
> This is a driver for the imx25 ADC/TSC module. It controls the
> touchscreen conversion queue and creates a touchscreen input device.
> The driver currently only supports 4 wire touchscreens. The driver uses
> a simple conversion queue of precharge, touch detection, X measurement,
> Y measurement, precharge and another touch detection.
> 
> This driver uses the regmap from the parent to setup some touch specific
> settings in the core driver and setup a idle configuration with touch
> detection.
> 
> Signed-off-by: Markus Pargmann <[email-masked]>
> Signed-off-by: Denis Carikli <[email-masked]>
> 
> [fix clock's period calculation]
> [fix calculation of the 'settling' value]
> Signed-off-by: Juergen Borleis <[email-masked]>
> ---
> 
> Notes:
>     Changes in v7:
>      - Moved clk_prepare_enable() and mx25_tcq_init() into mx25_tcq_open(). This
>        was done to be able to use devm_request_threaded_irq().
>      - Cleanup of the probe function through above change
>      - Removed mx25_tcq_remove(), not necessary now
> 
>  drivers/input/touchscreen/Kconfig         |   6 +
>  drivers/input/touchscreen/Makefile        |   1 +
>  drivers/input/touchscreen/fsl-imx25-tcq.c | 600 ++++++++++++++++++++++++++++++
>  3 files changed, 607 insertions(+)
>  create mode 100644 drivers/input/touchscreen/fsl-imx25-tcq.c
> 
> diff --git a/drivers/input/touchscreen/Kconfig b/drivers/input/touchscreen/Kconfig
> index ae33da7ab51f..b44651d33080 100644
> --- a/drivers/input/touchscreen/Kconfig
> +++ b/drivers/input/touchscreen/Kconfig
> @@ -811,6 +811,12 @@ config TOUCHSCREEN_USB_COMPOSITE
>  	  To compile this driver as a module, choose M here: the
>  	  module will be called usbtouchscreen.
>  
> +config TOUCHSCREEN_MX25
> +	tristate "Freescale i.MX25 touchscreen input driver"
> +	depends on MFD_MX25_TSADC
> +	help
> +	  Enable support for touchscreen connected to your i.MX25.
> +

	  To compile this driver as a module...

>  config TOUCHSCREEN_MC13783
>  	tristate "Freescale MC13783 touchscreen input driver"
>  	depends on MFD_MC13XXX
> diff --git a/drivers/input/touchscreen/Makefile b/drivers/input/touchscreen/Makefile
> index cbaa6abb08da..77a2ac54101a 100644
> --- a/drivers/input/touchscreen/Makefile
> +++ b/drivers/input/touchscreen/Makefile
> @@ -45,6 +45,7 @@ obj-$(CONFIG_TOUCHSCREEN_INTEL_MID)	+= intel-mid-touch.o
>  obj-$(CONFIG_TOUCHSCREEN_IPROC)		+= bcm_iproc_tsc.o
>  obj-$(CONFIG_TOUCHSCREEN_LPC32XX)	+= lpc32xx_ts.o
>  obj-$(CONFIG_TOUCHSCREEN_MAX11801)	+= max11801_ts.o
> +obj-$(CONFIG_TOUCHSCREEN_MX25)		+= fsl-imx25-tcq.o
>  obj-$(CONFIG_TOUCHSCREEN_MC13783)	+= mc13783_ts.o
>  obj-$(CONFIG_TOUCHSCREEN_MCS5000)	+= mcs5000_ts.o
>  obj-$(CONFIG_TOUCHSCREEN_MIGOR)		+= migor_ts.o
> diff --git a/drivers/input/touchscreen/fsl-imx25-tcq.c b/drivers/input/touchscreen/fsl-imx25-tcq.c
> new file mode 100644
> index 000000000000..c833cd814972
> --- /dev/null
> +++ b/drivers/input/touchscreen/fsl-imx25-tcq.c
> @@ -0,0 +1,600 @@
> +/*
> + * Copyright (C) 2014-2015 Pengutronix, Markus Pargmann <[email-masked]>
> + *
> + * This program is free software; you can redistribute it and/or modify it under
> + * the terms of the GNU General Public License version 2 as published by the
> + * Free Software Foundation.
> + *
> + * Based on driver from 2011:
> + *   Juergen Beisert, Pengutronix <[email-masked]>
> + *
> + * This is the driver for the imx25 TCQ (Touchscreen Conversion Queue)
> + * connected to the imx25 ADC.
> + */
> +
> +#include <linux/clk.h>
> +#include <linux/device.h>
> +#include <linux/input.h>
> +#include <linux/interrupt.h>
> +#include <linux/mfd/imx25-tsadc.h>
> +#include <linux/module.h>
> +#include <linux/of.h>
> +#include <linux/platform_device.h>
> +#include <linux/regmap.h>
> +
> +static const char mx25_tcq_name[] = "mx25-tcq";
> +
> +enum mx25_tcq_mode {
> +	MX25_TS_4WIRE,
> +};
> +
> +struct mx25_tcq_priv {
> +	struct regmap *regs;
> +	struct regmap *core_regs;
> +	struct input_dev *idev;
> +	enum mx25_tcq_mode mode;
> +	unsigned int pen_threshold;
> +	unsigned int sample_count;
> +	unsigned int expected_samples;
> +	unsigned int pen_debounce;
> +	unsigned int settling_time;
> +	struct clk *clk;
> +	int irq;
> +};
> +
> +static struct regmap_config mx25_tcq_regconfig = {
> +	.fast_io = true,
> +	.max_register = 0x5c,
> +	.reg_bits = 32,
> +	.val_bits = 32,
> +	.reg_stride = 4,
> +};
> +
> +static const struct of_device_id mx25_tcq_ids[] = {
> +	{ .compatible = "fsl,imx25-tcq", },
> +	{ /* Sentinel */ }
> +};
> +
> +#define TSC_4WIRE_PRE_INDEX 0
> +#define TSC_4WIRE_X_INDEX 1
> +#define TSC_4WIRE_Y_INDEX 2
> +#define TSC_4WIRE_POST_INDEX 3
> +#define TSC_4WIRE_LEAVE 4
> +
> +#define MX25_TSC_DEF_THRESHOLD 80
> +#define TSC_MAX_SAMPLES 16
> +
> +#define MX25_TSC_REPEAT_WAIT 14
> +
> +enum mx25_adc_configurations {
> +	MX25_CFG_PRECHARGE = 0,
> +	MX25_CFG_TOUCH_DETECT,
> +	MX25_CFG_X_MEASUREMENT,
> +	MX25_CFG_Y_MEASUREMENT,
> +};
> +
> +#define MX25_PRECHARGE_VALUE (\
> +			MX25_ADCQ_CFG_YPLL_OFF | \
> +			MX25_ADCQ_CFG_XNUR_OFF | \
> +			MX25_ADCQ_CFG_XPUL_HIGH | \
> +			MX25_ADCQ_CFG_REFP_INT | \
> +			MX25_ADCQ_CFG_IN_XP | \
> +			MX25_ADCQ_CFG_REFN_NGND2 | \
> +			MX25_ADCQ_CFG_IGS)
> +
> +#define MX25_TOUCH_DETECT_VALUE (\
> +			MX25_ADCQ_CFG_YNLR | \
> +			MX25_ADCQ_CFG_YPLL_OFF | \
> +			MX25_ADCQ_CFG_XNUR_OFF | \
> +			MX25_ADCQ_CFG_XPUL_OFF | \
> +			MX25_ADCQ_CFG_REFP_INT | \
> +			MX25_ADCQ_CFG_IN_XP | \
> +			MX25_ADCQ_CFG_REFN_NGND2 | \
> +			MX25_ADCQ_CFG_PENIACK)
> +
> +static void imx25_setup_queue_cfgs(struct mx25_tcq_priv *priv,
> +				   unsigned int settling_cnt)
> +{
> +	u32 precharge_cfg =
> +			MX25_PRECHARGE_VALUE |
> +			MX25_ADCQ_CFG_SETTLING_TIME(settling_cnt);
> +	u32 touch_detect_cfg =
> +			MX25_TOUCH_DETECT_VALUE |
> +			MX25_ADCQ_CFG_NOS(1) |
> +			MX25_ADCQ_CFG_SETTLING_TIME(settling_cnt);
> +
> +	regmap_write(priv->core_regs, MX25_TSC_TICR, precharge_cfg);
> +
> +	/* PRECHARGE */
> +	regmap_write(priv->regs, MX25_ADCQ_CFG(MX25_CFG_PRECHARGE),
> +		     precharge_cfg);
> +
> +	/* TOUCH_DETECT */
> +	regmap_write(priv->regs, MX25_ADCQ_CFG(MX25_CFG_TOUCH_DETECT),
> +		     touch_detect_cfg);
> +
> +	/* X Measurement */
> +	regmap_write(priv->regs, MX25_ADCQ_CFG(MX25_CFG_X_MEASUREMENT),
> +		     MX25_ADCQ_CFG_YPLL_OFF |
> +		     MX25_ADCQ_CFG_XNUR_LOW |
> +		     MX25_ADCQ_CFG_XPUL_HIGH |
> +		     MX25_ADCQ_CFG_REFP_XP |
> +		     MX25_ADCQ_CFG_IN_YP |
> +		     MX25_ADCQ_CFG_REFN_XN |
> +		     MX25_ADCQ_CFG_NOS(priv->sample_count) |
> +		     MX25_ADCQ_CFG_SETTLING_TIME(settling_cnt));
> +
> +	/* Y Measurement */
> +	regmap_write(priv->regs, MX25_ADCQ_CFG(MX25_CFG_Y_MEASUREMENT),
> +		     MX25_ADCQ_CFG_YNLR |
> +		     MX25_ADCQ_CFG_YPLL_HIGH |
> +		     MX25_ADCQ_CFG_XNUR_OFF |
> +		     MX25_ADCQ_CFG_XPUL_OFF |
> +		     MX25_ADCQ_CFG_REFP_YP |
> +		     MX25_ADCQ_CFG_IN_XP |
> +		     MX25_ADCQ_CFG_REFN_YN |
> +		     MX25_ADCQ_CFG_NOS(priv->sample_count) |
> +		     MX25_ADCQ_CFG_SETTLING_TIME(settling_cnt));
> +
> +	/* Enable the touch detection right now */
> +	regmap_write(priv->core_regs, MX25_TSC_TICR, touch_detect_cfg |
> +		     MX25_ADCQ_CFG_IGS);
> +}
> +
> +static int imx25_setup_queue_4wire(struct mx25_tcq_priv *priv,
> +				   unsigned settling_cnt, int *items)
> +{
> +	imx25_setup_queue_cfgs(priv, settling_cnt);
> +
> +	/* Setup the conversion queue */
> +	regmap_write(priv->regs, MX25_ADCQ_ITEM_7_0,
> +		     MX25_ADCQ_ITEM(0, MX25_CFG_PRECHARGE) |
> +		     MX25_ADCQ_ITEM(1, MX25_CFG_TOUCH_DETECT) |
> +		     MX25_ADCQ_ITEM(2, MX25_CFG_X_MEASUREMENT) |
> +		     MX25_ADCQ_ITEM(3, MX25_CFG_Y_MEASUREMENT) |
> +		     MX25_ADCQ_ITEM(4, MX25_CFG_PRECHARGE) |
> +		     MX25_ADCQ_ITEM(5, MX25_CFG_TOUCH_DETECT));
> +
> +	/*
> +	 * We measure X/Y with 'sample_count' number of samples and execute a
> +	 * touch detection twice, with 1 sample each
> +	 */
> +	priv->expected_samples = priv->sample_count * 2 + 2;
> +	*items = 6;
> +
> +	return 0;
> +}
> +
> +static void mx25_tcq_disable_touch_irq(struct mx25_tcq_priv *priv)
> +{
> +	regmap_update_bits(priv->regs, MX25_ADCQ_CR, MX25_ADCQ_CR_PDMSK,
> +			   MX25_ADCQ_CR_PDMSK);
> +}
> +
> +static void mx25_tcq_enable_touch_irq(struct mx25_tcq_priv *priv)
> +{
> +	regmap_update_bits(priv->regs, MX25_ADCQ_CR, MX25_ADCQ_CR_PDMSK, 0);
> +}
> +
> +static void mx25_tcq_disable_fifo_irq(struct mx25_tcq_priv *priv)
> +{
> +	regmap_update_bits(priv->regs, MX25_ADCQ_MR, MX25_ADCQ_MR_FDRY_IRQ,
> +			   MX25_ADCQ_MR_FDRY_IRQ);
> +}
> +
> +static void mx25_tcq_enable_fifo_irq(struct mx25_tcq_priv *priv)
> +{
> +	regmap_update_bits(priv->regs, MX25_ADCQ_MR, MX25_ADCQ_MR_FDRY_IRQ, 0);
> +}
> +
> +static void mx25_tcq_force_queue_start(struct mx25_tcq_priv *priv)
> +{
> +	regmap_update_bits(priv->regs, MX25_ADCQ_CR,
> +			   MX25_ADCQ_CR_FQS,
> +			   MX25_ADCQ_CR_FQS);
> +}
> +
> +static void mx25_tcq_force_queue_stop(struct mx25_tcq_priv *priv)
> +{
> +	regmap_update_bits(priv->regs, MX25_ADCQ_CR,
> +			   MX25_ADCQ_CR_FQS, 0);
> +}
> +
> +static void mx25_tcq_fifo_reset(struct mx25_tcq_priv *priv)
> +{
> +	u32 tcqcr;
> +
> +	regmap_read(priv->regs, MX25_ADCQ_CR, &tcqcr);
> +	regmap_update_bits(priv->regs, MX25_ADCQ_CR, MX25_ADCQ_CR_FRST,
> +			   MX25_ADCQ_CR_FRST);
> +	regmap_update_bits(priv->regs, MX25_ADCQ_CR, MX25_ADCQ_CR_FRST, 0);
> +	regmap_write(priv->regs, MX25_ADCQ_CR, tcqcr);
> +}
> +
> +static void mx25_tcq_re_enable_touch_detection(struct mx25_tcq_priv *priv)
> +{
> +	/* stop the queue from looping */
> +	mx25_tcq_force_queue_stop(priv);
> +
> +	/* for a clean touch detection, preload the X plane */
> +	regmap_write(priv->core_regs, MX25_TSC_TICR, MX25_PRECHARGE_VALUE);
> +
> +	/* waste some time now to pre-load the X plate to high voltage */
> +	mx25_tcq_fifo_reset(priv);
> +
> +	/* re-enable the detection right now */
> +	regmap_write(priv->core_regs, MX25_TSC_TICR,
> +		     MX25_TOUCH_DETECT_VALUE | MX25_ADCQ_CFG_IGS);
> +
> +	regmap_update_bits(priv->regs, MX25_ADCQ_SR, MX25_ADCQ_SR_PD,
> +			   MX25_ADCQ_SR_PD);
> +
> +	/* enable the pen down event to be a source for the interrupt */
> +	regmap_update_bits(priv->regs, MX25_ADCQ_MR, MX25_ADCQ_MR_PD_IRQ, 0);
> +
> +	/* lets fire the next IRQ if someone touches the touchscreen */
> +	mx25_tcq_enable_touch_irq(priv);
> +}
> +
> +static int mx25_tcq_create_event_for_4wire(struct mx25_tcq_priv *priv,

Why not void? What callers are supposed to do with the value?

> +					   u32 *sample_buf,
> +					   unsigned int samples)
> +{
> +	unsigned int x_pos = 0;
> +	unsigned int y_pos = 0;
> +	unsigned int touch_pre = 0;
> +	unsigned int touch_post = 0;
> +	unsigned int i;
> +	int ret = 0;
> +
> +	for (i = 0; i < samples; i++) {
> +		unsigned int index = MX25_ADCQ_FIFO_ID(sample_buf[i]);
> +		unsigned int val = MX25_ADCQ_FIFO_DATA(sample_buf[i]);
> +
> +		switch (index) {
> +		case 1:
> +			touch_pre = val;
> +			break;
> +		case 2:
> +			x_pos = val;
> +			break;
> +		case 3:
> +			y_pos = val;
> +			break;
> +		case 5:
> +			touch_post = val;
> +			break;
> +		default:
> +			ret = -EINVAL;
> +			break;
> +		}
> +	}
> +
> +	if (ret == 0 && samples != 0) {

Where do we set ret to anything other than 0?

> +		/*
> +		 * only if both touch measures are below a threshold,
> +		 * the position is valid
> +		 */
> +		if (touch_pre < priv->pen_threshold &&
> +		    touch_post < priv->pen_threshold) {
> +			/* valid samples, generate a report */
> +			x_pos /= priv->sample_count;
> +			y_pos /= priv->sample_count;
> +			input_report_abs(priv->idev, ABS_X, x_pos);
> +			input_report_abs(priv->idev, ABS_Y, y_pos);
> +			input_report_key(priv->idev, BTN_TOUCH, 1);
> +			input_sync(priv->idev);
> +
> +			/* get next sample */
> +			mx25_tcq_enable_fifo_irq(priv);
> +		} else if (touch_pre >= priv->pen_threshold &&
> +			   touch_post >= priv->pen_threshold) {
> +			/*
> +			 * if both samples are invalid,
> +			 * generate a release report
> +			 */
> +			input_report_key(priv->idev, BTN_TOUCH, 0);
> +			input_sync(priv->idev);
> +			mx25_tcq_re_enable_touch_detection(priv);
> +		} else {
> +			/*
> +			 * if only one of both touch measurements are
> +			 * below the threshold, still some bouncing
> +			 * happens. Take additional samples in this
> +			 * case to be sure
> +			 */
> +			mx25_tcq_enable_fifo_irq(priv);
> +		}
> +	}
> +
> +	return ret;
> +}
> +
> +static irqreturn_t mx25_tcq_irq_thread(int irq, void *dev_id)
> +{
> +	struct mx25_tcq_priv *priv = dev_id;
> +	u32 sample_buf[TSC_MAX_SAMPLES];
> +	unsigned int samples = 0;
> +
> +	/* read all samples */
> +	while (1) {
> +		u32 stats;
> +
> +		regmap_read(priv->regs, MX25_ADCQ_SR, &stats);
> +		if (stats & MX25_ADCQ_SR_EMPT)
> +			break;
> +
> +		if (samples < TSC_MAX_SAMPLES) {
> +			regmap_read(priv->regs, MX25_ADCQ_FIFO,
> +				    &sample_buf[samples]);
> +			++samples;
> +		} else {
> +			u32 discarded;
> +			/* discard samples */
> +			regmap_read(priv->regs, MX25_ADCQ_FIFO, &discarded);
> +		}
> +	}
> +
> +	mx25_tcq_create_event_for_4wire(priv, sample_buf, samples);
> +
> +	return IRQ_HANDLED;
> +}
> +
> +static irqreturn_t mx25_tcq_irq(int irq, void *dev_id)
> +{
> +	struct mx25_tcq_priv *priv = dev_id;
> +	u32 stat;
> +	int ret = IRQ_HANDLED;
> +
> +	regmap_read(priv->regs, MX25_ADCQ_SR, &stat);

Is there any concern that these reads will fail?

> +
> +	if (stat & (MX25_ADCQ_SR_FRR | MX25_ADCQ_SR_FUR | MX25_ADCQ_SR_FOR))
> +		mx25_tcq_fifo_reset(priv);
> +
> +	if (stat & MX25_ADCQ_SR_PD) {
> +		mx25_tcq_disable_touch_irq(priv);
> +		mx25_tcq_force_queue_start(priv);
> +		mx25_tcq_enable_fifo_irq(priv);
> +	}
> +
> +	if (stat & MX25_ADCQ_SR_FDRY) {
> +		mx25_tcq_disable_fifo_irq(priv);
> +		ret = IRQ_WAKE_THREAD;
> +	}
> +
> +	regmap_update_bits(priv->regs, MX25_ADCQ_SR, MX25_ADCQ_SR_FRR |
> +			   MX25_ADCQ_SR_FUR | MX25_ADCQ_SR_FOR |
> +			   MX25_ADCQ_SR_PD | MX25_ADCQ_SR_EOQ,
> +			   MX25_ADCQ_SR_FRR | MX25_ADCQ_SR_FUR |
> +			   MX25_ADCQ_SR_FOR | MX25_ADCQ_SR_PD |
> +			   MX25_ADCQ_SR_EOQ);
> +
> +	return ret;
> +}
> +
> +/* configure the statemachine for a 4-wire touchscreen */
> +static int mx25_tcq_init(struct mx25_tcq_priv *priv)
> +{
> +	u32 tgcr;
> +	unsigned int ipg_div;
> +	unsigned int adc_period;
> +	unsigned int debounce_cnt;
> +	unsigned int settling_cnt;
> +	int itemct;
> +	int ret;
> +
> +	regmap_read(priv->core_regs, MX25_TSC_TGCR, &tgcr);
> +	ipg_div = max_t(unsigned int, 4, MX25_TGCR_GET_ADCCLK(tgcr));
> +	adc_period = USEC_PER_SEC * ipg_div * 2 + 2;
> +	adc_period /= clk_get_rate(priv->clk) / 1000 + 1;
> +	debounce_cnt = DIV_ROUND_UP(priv->pen_debounce, adc_period * 8) - 1;
> +	settling_cnt = DIV_ROUND_UP(priv->settling_time, adc_period * 8) - 1;
> +
> +	/* Reset */
> +	regmap_write(priv->regs, MX25_ADCQ_CR,
> +		     MX25_ADCQ_CR_QRST | MX25_ADCQ_CR_FRST);
> +	regmap_update_bits(priv->regs, MX25_ADCQ_CR,
> +			   MX25_ADCQ_CR_QRST | MX25_ADCQ_CR_FRST, 0);
> +
> +	/* up to 128 * 8 ADC clocks are possible */
> +	if (debounce_cnt > 127)
> +		debounce_cnt = 127;
> +
> +	/* up to 255 * 8 ADC clocks are possible */
> +	if (settling_cnt > 255)
> +		settling_cnt = 255;
> +
> +	ret = imx25_setup_queue_4wire(priv, settling_cnt, &itemct);
> +	if (ret)
> +		return ret;
> +
> +	regmap_update_bits(priv->regs, MX25_ADCQ_CR,
> +			   MX25_ADCQ_CR_LITEMID_MASK | MX25_ADCQ_CR_WMRK_MASK,
> +			   MX25_ADCQ_CR_LITEMID(itemct - 1) |
> +			   MX25_ADCQ_CR_WMRK(priv->expected_samples - 1));
> +
> +	/* setup debounce count */
> +	regmap_update_bits(priv->core_regs, MX25_TSC_TGCR,
> +			   MX25_TGCR_PDBTIME_MASK,
> +			   MX25_TGCR_PDBTIME(debounce_cnt));
> +
> +	/* enable debounce */
> +	regmap_update_bits(priv->core_regs, MX25_TSC_TGCR, MX25_TGCR_PDBEN,
> +			   MX25_TGCR_PDBEN);
> +	regmap_update_bits(priv->core_regs, MX25_TSC_TGCR, MX25_TGCR_PDEN,
> +			   MX25_TGCR_PDEN);
> +
> +	/* enable the engine on demand */
> +	regmap_update_bits(priv->regs, MX25_ADCQ_CR, MX25_ADCQ_CR_QSM_MASK,
> +			   MX25_ADCQ_CR_QSM_FQS);
> +
> +	/* Enable repeat and repeat wait */
> +	regmap_update_bits(priv->regs, MX25_ADCQ_CR,
> +			   MX25_ADCQ_CR_RPT | MX25_ADCQ_CR_RWAIT_MASK,
> +			   MX25_ADCQ_CR_RPT |
> +			   MX25_ADCQ_CR_RWAIT(MX25_TSC_REPEAT_WAIT));
> +
> +	mx25_tcq_re_enable_touch_detection(priv);
> +
> +	return 0;
> +}
> +
> +static int mx25_tcq_parse_dt(struct platform_device *pdev,
> +			     struct mx25_tcq_priv *priv)
> +{
> +	struct device_node *np = pdev->dev.of_node;
> +	u32 wires;
> +	int ret;
> +
> +	/* Setup defaults */
> +	priv->pen_threshold = 500;
> +	priv->sample_count = 3;
> +	priv->pen_debounce = 1000000;
> +	priv->settling_time = 250000;
> +
> +	ret = of_property_read_u32(np, "fsl,wires", &wires);
> +	if (ret) {
> +		dev_err(&pdev->dev, "Failed to find fsl,wires properties\n");
> +		return ret;
> +	}
> +
> +	if (wires == 4) {
> +		priv->mode = MX25_TS_4WIRE;
> +	} else {
> +		dev_err(&pdev->dev, "%u-wire mode not supported\n", wires);
> +		return -EINVAL;
> +	}
> +
> +	/* These are optional, we don't care about the return values */
> +	of_property_read_u32(np, "fsl,pen-threshold", &priv->pen_threshold);
> +	of_property_read_u32(np, "fsl,settling-time", &priv->settling_time);
> +	of_property_read_u32(np, "fsl,pen-debounce", &priv->pen_debounce);
> +
> +	return 0;
> +}
> +
> +static int mx25_tcq_open(struct input_dev *idev)
> +{
> +	struct device *dev = &idev->dev;
> +	struct mx25_tcq_priv *priv = dev_get_drvdata(dev);
> +	int ret;
> +
> +	ret = clk_prepare_enable(priv->clk);
> +	if (ret) {
> +		dev_err(dev, "Failed to enable ipg clock\n");
> +		return ret;
> +	}
> +
> +	ret = mx25_tcq_init(priv);
> +	if (ret) {
> +		dev_err(dev, "Failed to init tcq\n");
> +		clk_disable_unprepare(priv->clk);
> +		return ret;
> +	}
> +
> +	return 0;
> +}
> +
> +static void mx25_tcq_close(struct input_dev *idev)
> +{
> +	struct mx25_tcq_priv *priv = input_get_drvdata(idev);
> +
> +	mx25_tcq_force_queue_stop(priv);
> +	mx25_tcq_disable_touch_irq(priv);
> +	mx25_tcq_disable_fifo_irq(priv);
> +	clk_disable_unprepare(priv->clk);
> +}
> +
> +static int mx25_tcq_probe(struct platform_device *pdev)
> +{
> +	struct device *dev = &pdev->dev;
> +	struct input_dev *idev;
> +	struct mx25_tcq_priv *priv;
> +	struct mx25_tsadc *tsadc = dev_get_drvdata(pdev->dev.parent);
> +	struct resource *res;
> +	void __iomem *mem;
> +	int ret;

Personal preference: can we call variables that hold error codes and not
returned in success path (i.e. when we do explicit "return 0:' for
success) be called "error"?
> +
> +	priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
> +	if (!priv)
> +		return -ENOMEM;
> +
> +	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> +	mem = devm_ioremap_resource(dev, res);
> +	if (!mem)

devm_ioremap_resource() returns ERR_PTR-encoded pointer, you should not
test it for NULL bit rather for IS_ERR.

> +		return -ENOMEM;
> +
> +	ret = mx25_tcq_parse_dt(pdev, priv);
> +	if (ret)
> +		return ret;
> +
> +	priv->regs = devm_regmap_init_mmio(dev, mem, &mx25_tcq_regconfig);
> +	if (IS_ERR(priv->regs)) {
> +		dev_err(dev, "Failed to initialize regmap\n");
> +		return PTR_ERR(priv->regs);
> +	}
> +
> +	priv->irq = platform_get_irq(pdev, 0);
> +	if (priv->irq <= 0) {
> +		dev_err(dev, "Failed to get IRQ\n");
> +		return priv->irq;
> +	}
> +
> +	idev = devm_input_allocate_device(dev);
> +	if (!idev) {
> +		dev_err(dev, "Failed to allocate input device\n");
> +		return -ENOMEM;
> +	}
> +
> +	idev->name = mx25_tcq_name;
> +	idev->evbit[0] = BIT_MASK(EV_KEY) | BIT_MASK(EV_ABS);
> +	idev->keybit[BIT_WORD(BTN_TOUCH)] = BIT_MASK(BTN_TOUCH);

Replace the 2 lines above with:

	input_set_capability(idev, EV_BTN_TOUCH);

> +	input_set_abs_params(idev, ABS_X, 0, 0xfff, 0, 0);
> +	input_set_abs_params(idev, ABS_Y, 0, 0xfff, 0, 0);
> +
> +	idev->id.bustype = BUS_HOST;
> +	idev->open = mx25_tcq_open;
> +	idev->close = mx25_tcq_close;
> +
> +	priv->idev = idev;
> +	input_set_drvdata(idev, priv);
> +
> +	priv->core_regs = tsadc->regs;
> +	if (!priv->core_regs)
> +		return -EINVAL;
> +
> +	priv->clk = tsadc->clk;
> +	if (!priv->clk)
> +		return -EINVAL;
> +
> +	platform_set_drvdata(pdev, priv);
> +
> +	ret = input_register_device(idev);
> +	if (ret) {
> +		dev_err(dev, "Failed to register input device\n");
> +		return ret;
> +	}
> +
> +	ret = devm_request_threaded_irq(dev, priv->irq, mx25_tcq_irq,
> +					mx25_tcq_irq_thread, IRQF_ONESHOT,
> +					pdev->name, priv);
> +	if (ret) {
> +		dev_err(dev, "Failed requesting IRQ\n");
> +		return ret;
> +	}

Is it possible that we enable interrupt generation in the controller (in
mx25_tcq_open) before we request IRQ and then (if someone touches the
screen) we'll get a spurious IRQ? I'd rather we swapped
devm_request_threaded_irq() and input_register_device(): it is perfectly
safe to use (send events) to allocated but not registered input device.

> +
> +	return 0;
> +}
> +
> +static struct platform_driver mx25_tcq_driver = {
> +	.driver		= {
> +		.name	= "mx25-tcq",
> +		.of_match_table = mx25_tcq_ids,
> +	},
> +	.probe		= mx25_tcq_probe,
> +};
> +module_platform_driver(mx25_tcq_driver);
> +
> +MODULE_DESCRIPTION("TS input driver for Freescale mx25");
> +MODULE_AUTHOR("Markus Pargmann <[email-masked]>");
> +MODULE_LICENSE("GPL v2");
> -- 
> 2.6.1
> 

Thanks.

-- 
Dmitry