/*
   * ADS7846 based touchscreen and sensor driver
   *
   * Copyright (c) 2005 David Brownell
   * Copyright (c) 2006 Nokia Corporation
   * Various changes: Imre Deak <imre.deak@nokia.com>
   *
   * Using code from:
   *  - corgi_ts.c
   *	Copyright (C) 2004-2005 Richard Purdie
   *  - omap_ts.[hc], ads7846.h, ts_osk.c
   *	Copyright (C) 2002 MontaVista Software
   *	Copyright (C) 2004 Texas Instruments
   *	Copyright (C) 2005 Dirk Behme
   *
   *  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.
   */
  #include <linux/types.h>
  #include <linux/hwmon.h>
  #include <linux/err.h>
  #include <linux/sched.h>
  #include <linux/delay.h>
  #include <linux/input.h>
  #include <linux/interrupt.h>
  #include <linux/slab.h>
  #include <linux/pm.h>
  #include <linux/of.h>
  #include <linux/of_gpio.h>
  #include <linux/of_device.h>
  #include <linux/gpio.h>
  #include <linux/spi/spi.h>
  #include <linux/spi/ads7846.h>
  #include <linux/regulator/consumer.h>
  #include <linux/module.h>
  #include <asm/irq.h>
  
  /*
   * This code has been heavily tested on a Nokia 770, and lightly
   * tested on other ads7846 devices (OSK/Mistral, Lubbock, Spitz).
   * TSC2046 is just newer ads7846 silicon.
   * Support for ads7843 tested on Atmel at91sam926x-EK.
   * Support for ads7845 has only been stubbed in.
   * Support for Analog Devices AD7873 and AD7843 tested.
   *
   * IRQ handling needs a workaround because of a shortcoming in handling
   * edge triggered IRQs on some platforms like the OMAP1/2. These
   * platforms don't handle the ARM lazy IRQ disabling properly, thus we
   * have to maintain our own SW IRQ disabled status. This should be
   * removed as soon as the affected platform's IRQ handling is fixed.
   *
   * App note sbaa036 talks in more detail about accurate sampling...
   * that ought to help in situations like LCDs inducing noise (which
   * can also be helped by using synch signals) and more generally.
   * This driver tries to utilize the measures described in the app
   * note. The strength of filtering can be set in the board-* specific
   * files.
   */
  
  #define TS_POLL_DELAY	1	/* ms delay before the first sample */
  #define TS_POLL_PERIOD	5	/* ms delay between samples */
  
  /* this driver doesn't aim at the peak continuous sample rate */
  #define	SAMPLE_BITS	(8 /*cmd*/ + 16 /*sample*/ + 2 /* before, after */)
  
  struct ts_event {
  	/*
  	 * For portability, we can't read 12 bit values using SPI (which
  	 * would make the controller deliver them as native byte order u16
  	 * with msbs zeroed).  Instead, we read them as two 8-bit values,
  	 * *** WHICH NEED BYTESWAPPING *** and range adjustment.
  	 */
  	u16	x;
  	u16	y;
  	u16	z1, z2;
  	bool	ignore;
  	u8	x_buf[3];
  	u8	y_buf[3];
  };
  
  /*
   * We allocate this separately to avoid cache line sharing issues when
   * driver is used with DMA-based SPI controllers (like atmel_spi) on
   * systems where main memory is not DMA-coherent (most non-x86 boards).
   */
  struct ads7846_packet {
  	u8			read_x, read_y, read_z1, read_z2, pwrdown;
  	u16			dummy;		/* for the pwrdown read */
  	struct ts_event		tc;
  	/* for ads7845 with mpc5121 psc spi we use 3-byte buffers */
  	u8			read_x_cmd[3], read_y_cmd[3], pwrdown_cmd[3];
  };
  
  struct ads7846 {
  	struct input_dev	*input;
  	char			phys[32];
  	char			name[32];
  
  	struct spi_device	*spi;
  	struct regulator	*reg;
  
  #if IS_ENABLED(CONFIG_HWMON)
  	struct device		*hwmon;
  #endif
  
  	u16			model;
  	u16			vref_mv;
  	u16			vref_delay_usecs;
  	u16			x_plate_ohms;
  	u16			pressure_max;
  
  	bool			swap_xy;
  	bool			use_internal;
  
  	struct ads7846_packet	*packet;
  
  	struct spi_transfer	xfer[18];
  	struct spi_message	msg[5];
  	int			msg_count;
  	wait_queue_head_t	wait;
  
  	bool			pendown;
  
  	int			read_cnt;
  	int			read_rep;
  	int			last_read;
  
  	u16			debounce_max;
  	u16			debounce_tol;
  	u16			debounce_rep;
  
  	u16			penirq_recheck_delay_usecs;
  
  	struct mutex		lock;
  	bool			stopped;	/* P: lock */
  	bool			disabled;	/* P: lock */
  	bool			suspended;	/* P: lock */
  
  	int			(*filter)(void *data, int data_idx, int *val);
  	void			*filter_data;
  	void			(*filter_cleanup)(void *data);
  	int			(*get_pendown_state)(void);
  	int			gpio_pendown;
  
  	void			(*wait_for_sync)(void);
  };
  
  /* leave chip selected when we're done, for quicker re-select? */
  #if	0
  #define	CS_CHANGE(xfer)	((xfer).cs_change = 1)
  #else
  #define	CS_CHANGE(xfer)	((xfer).cs_change = 0)
  #endif
  
  /*--------------------------------------------------------------------------*/
  
  /* The ADS7846 has touchscreen and other sensors.
   * Earlier ads784x chips are somewhat compatible.
   */
  #define	ADS_START		(1 << 7)
  #define	ADS_A2A1A0_d_y		(1 << 4)	/* differential */
  #define	ADS_A2A1A0_d_z1		(3 << 4)	/* differential */
  #define	ADS_A2A1A0_d_z2		(4 << 4)	/* differential */
  #define	ADS_A2A1A0_d_x		(5 << 4)	/* differential */
  #define	ADS_A2A1A0_temp0	(0 << 4)	/* non-differential */
  #define	ADS_A2A1A0_vbatt	(2 << 4)	/* non-differential */
  #define	ADS_A2A1A0_vaux		(6 << 4)	/* non-differential */
  #define	ADS_A2A1A0_temp1	(7 << 4)	/* non-differential */
  #define	ADS_8_BIT		(1 << 3)
  #define	ADS_12_BIT		(0 << 3)
  #define	ADS_SER			(1 << 2)	/* non-differential */
  #define	ADS_DFR			(0 << 2)	/* differential */
  #define	ADS_PD10_PDOWN		(0 << 0)	/* low power mode + penirq */
  #define	ADS_PD10_ADC_ON		(1 << 0)	/* ADC on */
  #define	ADS_PD10_REF_ON		(2 << 0)	/* vREF on + penirq */
  #define	ADS_PD10_ALL_ON		(3 << 0)	/* ADC + vREF on */
  
  #define	MAX_12BIT	((1<<12)-1)
  
  /* leave ADC powered up (disables penirq) between differential samples */
  #define	READ_12BIT_DFR(x, adc, vref) (ADS_START | ADS_A2A1A0_d_ ## x \
  	| ADS_12_BIT | ADS_DFR | \
  	(adc ? ADS_PD10_ADC_ON : 0) | (vref ? ADS_PD10_REF_ON : 0))
  
  #define	READ_Y(vref)	(READ_12BIT_DFR(y,  1, vref))
  #define	READ_Z1(vref)	(READ_12BIT_DFR(z1, 1, vref))
  #define	READ_Z2(vref)	(READ_12BIT_DFR(z2, 1, vref))
  
  #define	READ_X(vref)	(READ_12BIT_DFR(x,  1, vref))
  #define	PWRDOWN		(READ_12BIT_DFR(y,  0, 0))	/* LAST */
  
  /* single-ended samples need to first power up reference voltage;
   * we leave both ADC and VREF powered
   */
  #define	READ_12BIT_SER(x) (ADS_START | ADS_A2A1A0_ ## x \
  	| ADS_12_BIT | ADS_SER)
  
  #define	REF_ON	(READ_12BIT_DFR(x, 1, 1))
  #define	REF_OFF	(READ_12BIT_DFR(y, 0, 0))
  
  /* Must be called with ts->lock held */
  static void ads7846_stop(struct ads7846 *ts)
  {
  	if (!ts->disabled && !ts->suspended) {
  		/* Signal IRQ thread to stop polling and disable the handler. */
  		ts->stopped = true;
  		mb();
  		wake_up(&ts->wait);
  		disable_irq(ts->spi->irq);
  	}
  }
  
  /* Must be called with ts->lock held */
  static void ads7846_restart(struct ads7846 *ts)
  {
  	if (!ts->disabled && !ts->suspended) {
  		/* Tell IRQ thread that it may poll the device. */
  		ts->stopped = false;
  		mb();
  		enable_irq(ts->spi->irq);
  	}
  }
  
  /* Must be called with ts->lock held */
  static void __ads7846_disable(struct ads7846 *ts)
  {
  	ads7846_stop(ts);
  	regulator_disable(ts->reg);
  
  	/*
  	 * We know the chip's in low power mode since we always
  	 * leave it that way after every request
  	 */
  }
  
  /* Must be called with ts->lock held */
  static void __ads7846_enable(struct ads7846 *ts)
  {
  	int error;
  
  	error = regulator_enable(ts->reg);
  	if (error != 0)
  		dev_err(&ts->spi->dev, "Failed to enable supply: %d
  ", error);
  
  	ads7846_restart(ts);
  }
  
  static void ads7846_disable(struct ads7846 *ts)
  {
  	mutex_lock(&ts->lock);
  
  	if (!ts->disabled) {
  
  		if  (!ts->suspended)
  			__ads7846_disable(ts);
  
  		ts->disabled = true;
  	}
  
  	mutex_unlock(&ts->lock);
  }
  
  static void ads7846_enable(struct ads7846 *ts)
  {
  	mutex_lock(&ts->lock);
  
  	if (ts->disabled) {
  
  		ts->disabled = false;
  
  		if (!ts->suspended)
  			__ads7846_enable(ts);
  	}
  
  	mutex_unlock(&ts->lock);
  }
  
  /*--------------------------------------------------------------------------*/
  
  /*
   * Non-touchscreen sensors only use single-ended conversions.
   * The range is GND..vREF. The ads7843 and ads7835 must use external vREF;
   * ads7846 lets that pin be unconnected, to use internal vREF.
   */
  
  struct ser_req {
  	u8			ref_on;
  	u8			command;
  	u8			ref_off;
  	u16			scratch;
  	struct spi_message	msg;
  	struct spi_transfer	xfer[6];
  	/*
  	 * DMA (thus cache coherency maintenance) requires the
  	 * transfer buffers to live in their own cache lines.
  	 */
  	__be16 sample ____cacheline_aligned;
  };
  
  struct ads7845_ser_req {
  	u8			command[3];
  	struct spi_message	msg;
  	struct spi_transfer	xfer[2];
  	/*
  	 * DMA (thus cache coherency maintenance) requires the
  	 * transfer buffers to live in their own cache lines.
  	 */
  	u8 sample[3] ____cacheline_aligned;
  };
  
  static int ads7846_read12_ser(struct device *dev, unsigned command)
  {
  	struct spi_device *spi = to_spi_device(dev);
  	struct ads7846 *ts = dev_get_drvdata(dev);
  	struct ser_req *req;
  	int status;
  
  	req = kzalloc(sizeof *req, GFP_KERNEL);
  	if (!req)
  		return -ENOMEM;
  
  	spi_message_init(&req->msg);
  
  	/* maybe turn on internal vREF, and let it settle */
  	if (ts->use_internal) {
  		req->ref_on = REF_ON;
  		req->xfer[0].tx_buf = &req->ref_on;
  		req->xfer[0].len = 1;
  		spi_message_add_tail(&req->xfer[0], &req->msg);
  
  		req->xfer[1].rx_buf = &req->scratch;
  		req->xfer[1].len = 2;
  
  		/* for 1uF, settle for 800 usec; no cap, 100 usec.  */
  		req->xfer[1].delay_usecs = ts->vref_delay_usecs;
  		spi_message_add_tail(&req->xfer[1], &req->msg);
  
  		/* Enable reference voltage */
  		command |= ADS_PD10_REF_ON;
  	}
  
  	/* Enable ADC in every case */
  	command |= ADS_PD10_ADC_ON;
  
  	/* take sample */
  	req->command = (u8) command;
  	req->xfer[2].tx_buf = &req->command;
  	req->xfer[2].len = 1;
  	spi_message_add_tail(&req->xfer[2], &req->msg);
  
  	req->xfer[3].rx_buf = &req->sample;
  	req->xfer[3].len = 2;
  	spi_message_add_tail(&req->xfer[3], &req->msg);
  
  	/* REVISIT:  take a few more samples, and compare ... */
  
  	/* converter in low power mode & enable PENIRQ */
  	req->ref_off = PWRDOWN;
  	req->xfer[4].tx_buf = &req->ref_off;
  	req->xfer[4].len = 1;
  	spi_message_add_tail(&req->xfer[4], &req->msg);
  
  	req->xfer[5].rx_buf = &req->scratch;
  	req->xfer[5].len = 2;
  	CS_CHANGE(req->xfer[5]);
  	spi_message_add_tail(&req->xfer[5], &req->msg);
  
  	mutex_lock(&ts->lock);
  	ads7846_stop(ts);
  	status = spi_sync(spi, &req->msg);
  	ads7846_restart(ts);
  	mutex_unlock(&ts->lock);
  
  	if (status == 0) {
  		/* on-wire is a must-ignore bit, a BE12 value, then padding */
  		status = be16_to_cpu(req->sample);
  		status = status >> 3;
  		status &= 0x0fff;
  	}
  
  	kfree(req);
  	return status;
  }
  
  static int ads7845_read12_ser(struct device *dev, unsigned command)
  {
  	struct spi_device *spi = to_spi_device(dev);
  	struct ads7846 *ts = dev_get_drvdata(dev);
  	struct ads7845_ser_req *req;
  	int status;
  
  	req = kzalloc(sizeof *req, GFP_KERNEL);
  	if (!req)
  		return -ENOMEM;
  
  	spi_message_init(&req->msg);
  
  	req->command[0] = (u8) command;
  	req->xfer[0].tx_buf = req->command;
  	req->xfer[0].rx_buf = req->sample;
  	req->xfer[0].len = 3;
  	spi_message_add_tail(&req->xfer[0], &req->msg);
  
  	mutex_lock(&ts->lock);
  	ads7846_stop(ts);
  	status = spi_sync(spi, &req->msg);
  	ads7846_restart(ts);
  	mutex_unlock(&ts->lock);
  
  	if (status == 0) {
  		/* BE12 value, then padding */
  		status = be16_to_cpu(*((u16 *)&req->sample[1]));
  		status = status >> 3;
  		status &= 0x0fff;
  	}
  
  	kfree(req);
  	return status;
  }
  
  #if IS_ENABLED(CONFIG_HWMON)
  
  #define SHOW(name, var, adjust) static ssize_t \
  name ## _show(struct device *dev, struct device_attribute *attr, char *buf) \
  { \
  	struct ads7846 *ts = dev_get_drvdata(dev); \
  	ssize_t v = ads7846_read12_ser(dev, \
  			READ_12BIT_SER(var)); \
  	if (v < 0) \
  		return v; \
  	return sprintf(buf, "%u
  ", adjust(ts, v)); \
  } \
  static DEVICE_ATTR(name, S_IRUGO, name ## _show, NULL);
  
  
  /* Sysfs conventions report temperatures in millidegrees Celsius.
   * ADS7846 could use the low-accuracy two-sample scheme, but can't do the high
   * accuracy scheme without calibration data.  For now we won't try either;
   * userspace sees raw sensor values, and must scale/calibrate appropriately.
   */
  static inline unsigned null_adjust(struct ads7846 *ts, ssize_t v)
  {
  	return v;
  }
  
  SHOW(temp0, temp0, null_adjust)		/* temp1_input */
  SHOW(temp1, temp1, null_adjust)		/* temp2_input */
  
  
  /* sysfs conventions report voltages in millivolts.  We can convert voltages
   * if we know vREF.  userspace may need to scale vAUX to match the board's
   * external resistors; we assume that vBATT only uses the internal ones.
   */
  static inline unsigned vaux_adjust(struct ads7846 *ts, ssize_t v)
  {
  	unsigned retval = v;
  
  	/* external resistors may scale vAUX into 0..vREF */
  	retval *= ts->vref_mv;
  	retval = retval >> 12;
  
  	return retval;
  }
  
  static inline unsigned vbatt_adjust(struct ads7846 *ts, ssize_t v)
  {
  	unsigned retval = vaux_adjust(ts, v);
  
  	/* ads7846 has a resistor ladder to scale this signal down */
  	if (ts->model == 7846)
  		retval *= 4;
  
  	return retval;
  }
  
  SHOW(in0_input, vaux, vaux_adjust)
  SHOW(in1_input, vbatt, vbatt_adjust)
  
  static umode_t ads7846_is_visible(struct kobject *kobj, struct attribute *attr,
  				  int index)
  {
  	struct device *dev = container_of(kobj, struct device, kobj);
  	struct ads7846 *ts = dev_get_drvdata(dev);
  
  	if (ts->model == 7843 && index < 2)	/* in0, in1 */
  		return 0;
  	if (ts->model == 7845 && index != 2)	/* in0 */
  		return 0;
  
  	return attr->mode;
  }
  
  static struct attribute *ads7846_attributes[] = {
  	&dev_attr_temp0.attr,		/* 0 */
  	&dev_attr_temp1.attr,		/* 1 */
  	&dev_attr_in0_input.attr,	/* 2 */
  	&dev_attr_in1_input.attr,	/* 3 */
  	NULL,
  };
  
  static struct attribute_group ads7846_attr_group = {
  	.attrs = ads7846_attributes,
  	.is_visible = ads7846_is_visible,
  };
  __ATTRIBUTE_GROUPS(ads7846_attr);
  
  static int ads784x_hwmon_register(struct spi_device *spi, struct ads7846 *ts)
  {
  	/* hwmon sensors need a reference voltage */
  	switch (ts->model) {
  	case 7846:
  		if (!ts->vref_mv) {
  			dev_dbg(&spi->dev, "assuming 2.5V internal vREF
  ");
  			ts->vref_mv = 2500;
  			ts->use_internal = true;
  		}
  		break;
  	case 7845:
  	case 7843:
  		if (!ts->vref_mv) {
  			dev_warn(&spi->dev,
  				"external vREF for ADS%d not specified
  ",
  				ts->model);
  			return 0;
  		}
  		break;
  	}
  
  	ts->hwmon = hwmon_device_register_with_groups(&spi->dev, spi->modalias,
  						      ts, ads7846_attr_groups);
  	if (IS_ERR(ts->hwmon))
  		return PTR_ERR(ts->hwmon);
  
  	return 0;
  }
  
  static void ads784x_hwmon_unregister(struct spi_device *spi,
  				     struct ads7846 *ts)
  {
  	if (ts->hwmon)
  		hwmon_device_unregister(ts->hwmon);
  }
  
  #else
  static inline int ads784x_hwmon_register(struct spi_device *spi,
  					 struct ads7846 *ts)
  {
  	return 0;
  }
  
  static inline void ads784x_hwmon_unregister(struct spi_device *spi,
  					    struct ads7846 *ts)
  {
  }
  #endif
  
  static ssize_t ads7846_pen_down_show(struct device *dev,
  				     struct device_attribute *attr, char *buf)
  {
  	struct ads7846 *ts = dev_get_drvdata(dev);
  
  	return sprintf(buf, "%u
  ", ts->pendown);
  }
  
  static DEVICE_ATTR(pen_down, S_IRUGO, ads7846_pen_down_show, NULL);
  
  static ssize_t ads7846_disable_show(struct device *dev,
  				     struct device_attribute *attr, char *buf)
  {
  	struct ads7846 *ts = dev_get_drvdata(dev);
  
  	return sprintf(buf, "%u
  ", ts->disabled);
  }
  
  static ssize_t ads7846_disable_store(struct device *dev,
  				     struct device_attribute *attr,
  				     const char *buf, size_t count)
  {
  	struct ads7846 *ts = dev_get_drvdata(dev);
  	unsigned int i;
  	int err;
  
  	err = kstrtouint(buf, 10, &i);
  	if (err)
  		return err;
  
  	if (i)
  		ads7846_disable(ts);
  	else
  		ads7846_enable(ts);
  
  	return count;
  }
  
  static DEVICE_ATTR(disable, 0664, ads7846_disable_show, ads7846_disable_store);
  
  static struct attribute *ads784x_attributes[] = {
  	&dev_attr_pen_down.attr,
  	&dev_attr_disable.attr,
  	NULL,
  };
  
  static struct attribute_group ads784x_attr_group = {
  	.attrs = ads784x_attributes,
  };
  
  /*--------------------------------------------------------------------------*/
  
  static int get_pendown_state(struct ads7846 *ts)
  {
  	if (ts->get_pendown_state)
  		return ts->get_pendown_state();
  
  	return !gpio_get_value(ts->gpio_pendown);
  }
  
  static void null_wait_for_sync(void)
  {
  }
  
  static int ads7846_debounce_filter(void *ads, int data_idx, int *val)
  {
  	struct ads7846 *ts = ads;
  
  	if (!ts->read_cnt || (abs(ts->last_read - *val) > ts->debounce_tol)) {
  		/* Start over collecting consistent readings. */
  		ts->read_rep = 0;
  		/*
  		 * Repeat it, if this was the first read or the read
  		 * wasn't consistent enough.
  		 */
  		if (ts->read_cnt < ts->debounce_max) {
  			ts->last_read = *val;
  			ts->read_cnt++;
  			return ADS7846_FILTER_REPEAT;
  		} else {
  			/*
  			 * Maximum number of debouncing reached and still
  			 * not enough number of consistent readings. Abort
  			 * the whole sample, repeat it in the next sampling
  			 * period.
  			 */
  			ts->read_cnt = 0;
  			return ADS7846_FILTER_IGNORE;
  		}
  	} else {
  		if (++ts->read_rep > ts->debounce_rep) {
  			/*
  			 * Got a good reading for this coordinate,
  			 * go for the next one.
  			 */
  			ts->read_cnt = 0;
  			ts->read_rep = 0;
  			return ADS7846_FILTER_OK;
  		} else {
  			/* Read more values that are consistent. */
  			ts->read_cnt++;
  			return ADS7846_FILTER_REPEAT;
  		}
  	}
  }
  
  static int ads7846_no_filter(void *ads, int data_idx, int *val)
  {
  	return ADS7846_FILTER_OK;
  }
  
  static int ads7846_get_value(struct ads7846 *ts, struct spi_message *m)
  {
  	struct spi_transfer *t =
  		list_entry(m->transfers.prev, struct spi_transfer, transfer_list);
  
  	if (ts->model == 7845) {
  		return be16_to_cpup((__be16 *)&(((char*)t->rx_buf)[1])) >> 3;
  	} else {
  		/*
  		 * adjust:  on-wire is a must-ignore bit, a BE12 value, then
  		 * padding; built from two 8 bit values written msb-first.
  		 */
  		return be16_to_cpup((__be16 *)t->rx_buf) >> 3;
  	}
  }
  
  static void ads7846_update_value(struct spi_message *m, int val)
  {
  	struct spi_transfer *t =
  		list_entry(m->transfers.prev, struct spi_transfer, transfer_list);
  
  	*(u16 *)t->rx_buf = val;
  }
  
  static void ads7846_read_state(struct ads7846 *ts)
  {
  	struct ads7846_packet *packet = ts->packet;
  	struct spi_message *m;
  	int msg_idx = 0;
  	int val;
  	int action;
  	int error;
  
  	while (msg_idx < ts->msg_count) {
  
  		ts->wait_for_sync();
  
  		m = &ts->msg[msg_idx];
  		error = spi_sync(ts->spi, m);
  		if (error) {
  			dev_err(&ts->spi->dev, "spi_async --> %d
  ", error);
  			packet->tc.ignore = true;
  			return;
  		}
  
  		/*
  		 * Last message is power down request, no need to convert
  		 * or filter the value.
  		 */
  		if (msg_idx < ts->msg_count - 1) {
  
  			val = ads7846_get_value(ts, m);
  
  			action = ts->filter(ts->filter_data, msg_idx, &val);
  			switch (action) {
  			case ADS7846_FILTER_REPEAT:
  				continue;
  
  			case ADS7846_FILTER_IGNORE:
  				packet->tc.ignore = true;
  				msg_idx = ts->msg_count - 1;
  				continue;
  
  			case ADS7846_FILTER_OK:
  				ads7846_update_value(m, val);
  				packet->tc.ignore = false;
  				msg_idx++;
  				break;
  
  			default:
  				BUG();
  			}
  		} else {
  			msg_idx++;
  		}
  	}
  }
  
  static void ads7846_report_state(struct ads7846 *ts)
  {
  	struct ads7846_packet *packet = ts->packet;
  	unsigned int Rt;
  	u16 x, y, z1, z2;
  
  	/*
  	 * ads7846_get_value() does in-place conversion (including byte swap)
  	 * from on-the-wire format as part of debouncing to get stable
  	 * readings.
  	 */
  	if (ts->model == 7845) {
  		x = *(u16 *)packet->tc.x_buf;
  		y = *(u16 *)packet->tc.y_buf;
  		z1 = 0;
  		z2 = 0;
  	} else {
  		x = packet->tc.x;
  		y = packet->tc.y;
  		z1 = packet->tc.z1;
  		z2 = packet->tc.z2;
  	}
  
  	/* range filtering */
  	if (x == MAX_12BIT)
  		x = 0;
  
  	if (ts->model == 7843) {
  		Rt = ts->pressure_max / 2;
  	} else if (ts->model == 7845) {
  		if (get_pendown_state(ts))
  			Rt = ts->pressure_max / 2;
  		else
  			Rt = 0;
  		dev_vdbg(&ts->spi->dev, "x/y: %d/%d, PD %d
  ", x, y, Rt);
  	} else if (likely(x && z1)) {
  		/* compute touch pressure resistance using equation #2 */
  		Rt = z2;
  		Rt -= z1;
  		Rt *= x;
  		Rt *= ts->x_plate_ohms;
  		Rt /= z1;
  		Rt = (Rt + 2047) >> 12;
  	} else {
  		Rt = 0;
  	}
  
  	/*
  	 * Sample found inconsistent by debouncing or pressure is beyond
  	 * the maximum. Don't report it to user space, repeat at least
  	 * once more the measurement
  	 */
  	if (packet->tc.ignore || Rt > ts->pressure_max) {
  		dev_vdbg(&ts->spi->dev, "ignored %d pressure %d
  ",
  			 packet->tc.ignore, Rt);
  		return;
  	}
  
  	/*
  	 * Maybe check the pendown state before reporting. This discards
  	 * false readings when the pen is lifted.
  	 */
  	if (ts->penirq_recheck_delay_usecs) {
  		udelay(ts->penirq_recheck_delay_usecs);
  		if (!get_pendown_state(ts))
  			Rt = 0;
  	}
  
  	/*
  	 * NOTE: We can't rely on the pressure to determine the pen down
  	 * state, even this controller has a pressure sensor. The pressure
  	 * value can fluctuate for quite a while after lifting the pen and
  	 * in some cases may not even settle at the expected value.
  	 *
  	 * The only safe way to check for the pen up condition is in the
  	 * timer by reading the pen signal state (it's a GPIO _and_ IRQ).
  	 */
  	if (Rt) {
  		struct input_dev *input = ts->input;
  
  		if (ts->swap_xy)
  			swap(x, y);
  
  		if (!ts->pendown) {
  			input_report_key(input, BTN_TOUCH, 1);
  			ts->pendown = true;
  			dev_vdbg(&ts->spi->dev, "DOWN
  ");
  		}
  
  		input_report_abs(input, ABS_X, x);
  		input_report_abs(input, ABS_Y, y);
  		input_report_abs(input, ABS_PRESSURE, ts->pressure_max - Rt);
  
  		input_sync(input);
  		dev_vdbg(&ts->spi->dev, "%4d/%4d/%4d
  ", x, y, Rt);
  	}
  }
  
  static irqreturn_t ads7846_hard_irq(int irq, void *handle)
  {
  	struct ads7846 *ts = handle;
  
  	return get_pendown_state(ts) ? IRQ_WAKE_THREAD : IRQ_HANDLED;
  }
  
  
  static irqreturn_t ads7846_irq(int irq, void *handle)
  {
  	struct ads7846 *ts = handle;
  
  	/* Start with a small delay before checking pendown state */
  	msleep(TS_POLL_DELAY);
  
  	while (!ts->stopped && get_pendown_state(ts)) {
  
  		/* pen is down, continue with the measurement */
  		ads7846_read_state(ts);
  
  		if (!ts->stopped)
  			ads7846_report_state(ts);
  
  		wait_event_timeout(ts->wait, ts->stopped,
  				   msecs_to_jiffies(TS_POLL_PERIOD));
  	}
  
  	if (ts->pendown) {
  		struct input_dev *input = ts->input;
  
  		input_report_key(input, BTN_TOUCH, 0);
  		input_report_abs(input, ABS_PRESSURE, 0);
  		input_sync(input);
  
  		ts->pendown = false;
  		dev_vdbg(&ts->spi->dev, "UP
  ");
  	}
  
  	return IRQ_HANDLED;
  }
  
  #ifdef CONFIG_PM_SLEEP
  static int ads7846_suspend(struct device *dev)
  {
  	struct ads7846 *ts = dev_get_drvdata(dev);
  
  	mutex_lock(&ts->lock);
  
  	if (!ts->suspended) {
  
  		if (!ts->disabled)
  			__ads7846_disable(ts);
  
  		if (device_may_wakeup(&ts->spi->dev))
  			enable_irq_wake(ts->spi->irq);
  
  		ts->suspended = true;
  	}
  
  	mutex_unlock(&ts->lock);
  
  	return 0;
  }
  
  static int ads7846_resume(struct device *dev)
  {
  	struct ads7846 *ts = dev_get_drvdata(dev);
  
  	mutex_lock(&ts->lock);
  
  	if (ts->suspended) {
  
  		ts->suspended = false;
  
  		if (device_may_wakeup(&ts->spi->dev))
  			disable_irq_wake(ts->spi->irq);
  
  		if (!ts->disabled)
  			__ads7846_enable(ts);
  	}
  
  	mutex_unlock(&ts->lock);
  
  	return 0;
  }
  #endif
  
  static SIMPLE_DEV_PM_OPS(ads7846_pm, ads7846_suspend, ads7846_resume);
  
  static int ads7846_setup_pendown(struct spi_device *spi,
  				 struct ads7846 *ts,
  				 const struct ads7846_platform_data *pdata)
  {
  	int err;
  
  	/*
  	 * REVISIT when the irq can be triggered active-low, or if for some
  	 * reason the touchscreen isn't hooked up, we don't need to access
  	 * the pendown state.
  	 */
  
  	if (pdata->get_pendown_state) {
  		ts->get_pendown_state = pdata->get_pendown_state;
  	} else if (gpio_is_valid(pdata->gpio_pendown)) {
  
  		err = gpio_request_one(pdata->gpio_pendown, GPIOF_IN,
  				       "ads7846_pendown");
  		if (err) {
  			dev_err(&spi->dev,
  				"failed to request/setup pendown GPIO%d: %d
  ",
  				pdata->gpio_pendown, err);
  			return err;
  		}
  
  		ts->gpio_pendown = pdata->gpio_pendown;
  
  		if (pdata->gpio_pendown_debounce)
  			gpio_set_debounce(pdata->gpio_pendown,
  					  pdata->gpio_pendown_debounce);
  	} else {
  		dev_err(&spi->dev, "no get_pendown_state nor gpio_pendown?
  ");
  		return -EINVAL;
  	}
  
  	return 0;
  }
  
  /*
   * Set up the transfers to read touchscreen state; this assumes we
   * use formula #2 for pressure, not #3.
   */
  static void ads7846_setup_spi_msg(struct ads7846 *ts,
  				  const struct ads7846_platform_data *pdata)
  {
  	struct spi_message *m = &ts->msg[0];
  	struct spi_transfer *x = ts->xfer;
  	struct ads7846_packet *packet = ts->packet;
  	int vref = pdata->keep_vref_on;
  
  	if (ts->model == 7873) {
  		/*
  		 * The AD7873 is almost identical to the ADS7846
  		 * keep VREF off during differential/ratiometric
  		 * conversion modes.
  		 */
  		ts->model = 7846;
  		vref = 0;
  	}
  
  	ts->msg_count = 1;
  	spi_message_init(m);
  	m->context = ts;
  
  	if (ts->model == 7845) {
  		packet->read_y_cmd[0] = READ_Y(vref);
  		packet->read_y_cmd[1] = 0;
  		packet->read_y_cmd[2] = 0;
  		x->tx_buf = &packet->read_y_cmd[0];
  		x->rx_buf = &packet->tc.y_buf[0];
  		x->len = 3;
  		spi_message_add_tail(x, m);
  	} else {
  		/* y- still on; turn on only y+ (and ADC) */
  		packet->read_y = READ_Y(vref);
  		x->tx_buf = &packet->read_y;
  		x->len = 1;
  		spi_message_add_tail(x, m);
  
  		x++;
  		x->rx_buf = &packet->tc.y;
  		x->len = 2;
  		spi_message_add_tail(x, m);
  	}
  
  	/*
  	 * The first sample after switching drivers can be low quality;
  	 * optionally discard it, using a second one after the signals
  	 * have had enough time to stabilize.
  	 */
  	if (pdata->settle_delay_usecs) {
  		x->delay_usecs = pdata->settle_delay_usecs;
  
  		x++;
  		x->tx_buf = &packet->read_y;
  		x->len = 1;
  		spi_message_add_tail(x, m);
  
  		x++;
  		x->rx_buf = &packet->tc.y;
  		x->len = 2;
  		spi_message_add_tail(x, m);
  	}
  
  	ts->msg_count++;
  	m++;
  	spi_message_init(m);
  	m->context = ts;
  
  	if (ts->model == 7845) {
  		x++;
  		packet->read_x_cmd[0] = READ_X(vref);
  		packet->read_x_cmd[1] = 0;
  		packet->read_x_cmd[2] = 0;
  		x->tx_buf = &packet->read_x_cmd[0];
  		x->rx_buf = &packet->tc.x_buf[0];
  		x->len = 3;
  		spi_message_add_tail(x, m);
  	} else {
  		/* turn y- off, x+ on, then leave in lowpower */
  		x++;
  		packet->read_x = READ_X(vref);
  		x->tx_buf = &packet->read_x;
  		x->len = 1;
  		spi_message_add_tail(x, m);
  
  		x++;
  		x->rx_buf = &packet->tc.x;
  		x->len = 2;
  		spi_message_add_tail(x, m);
  	}
  
  	/* ... maybe discard first sample ... */
  	if (pdata->settle_delay_usecs) {
  		x->delay_usecs = pdata->settle_delay_usecs;
  
  		x++;
  		x->tx_buf = &packet->read_x;
  		x->len = 1;
  		spi_message_add_tail(x, m);
  
  		x++;
  		x->rx_buf = &packet->tc.x;
  		x->len = 2;
  		spi_message_add_tail(x, m);
  	}
  
  	/* turn y+ off, x- on; we'll use formula #2 */
  	if (ts->model == 7846) {
  		ts->msg_count++;
  		m++;
  		spi_message_init(m);
  		m->context = ts;
  
  		x++;
  		packet->read_z1 = READ_Z1(vref);
  		x->tx_buf = &packet->read_z1;
  		x->len = 1;
  		spi_message_add_tail(x, m);
  
  		x++;
  		x->rx_buf = &packet->tc.z1;
  		x->len = 2;
  		spi_message_add_tail(x, m);
  
  		/* ... maybe discard first sample ... */
  		if (pdata->settle_delay_usecs) {
  			x->delay_usecs = pdata->settle_delay_usecs;
  
  			x++;
  			x->tx_buf = &packet->read_z1;
  			x->len = 1;
  			spi_message_add_tail(x, m);
  
  			x++;
  			x->rx_buf = &packet->tc.z1;
  			x->len = 2;
  			spi_message_add_tail(x, m);
  		}
  
  		ts->msg_count++;
  		m++;
  		spi_message_init(m);
  		m->context = ts;
  
  		x++;
  		packet->read_z2 = READ_Z2(vref);
  		x->tx_buf = &packet->read_z2;
  		x->len = 1;
  		spi_message_add_tail(x, m);
  
  		x++;
  		x->rx_buf = &packet->tc.z2;
  		x->len = 2;
  		spi_message_add_tail(x, m);
  
  		/* ... maybe discard first sample ... */
  		if (pdata->settle_delay_usecs) {
  			x->delay_usecs = pdata->settle_delay_usecs;
  
  			x++;
  			x->tx_buf = &packet->read_z2;
  			x->len = 1;
  			spi_message_add_tail(x, m);
  
  			x++;
  			x->rx_buf = &packet->tc.z2;
  			x->len = 2;
  			spi_message_add_tail(x, m);
  		}
  	}
  
  	/* power down */
  	ts->msg_count++;
  	m++;
  	spi_message_init(m);
  	m->context = ts;
  
  	if (ts->model == 7845) {
  		x++;
  		packet->pwrdown_cmd[0] = PWRDOWN;
  		packet->pwrdown_cmd[1] = 0;
  		packet->pwrdown_cmd[2] = 0;
  		x->tx_buf = &packet->pwrdown_cmd[0];
  		x->len = 3;
  	} else {
  		x++;
  		packet->pwrdown = PWRDOWN;
  		x->tx_buf = &packet->pwrdown;
  		x->len = 1;
  		spi_message_add_tail(x, m);
  
  		x++;
  		x->rx_buf = &packet->dummy;
  		x->len = 2;
  	}
  
  	CS_CHANGE(*x);
  	spi_message_add_tail(x, m);
  }
  
  #ifdef CONFIG_OF
  static const struct of_device_id ads7846_dt_ids[] = {
  	{ .compatible = "ti,tsc2046",	.data = (void *) 7846 },
  	{ .compatible = "ti,ads7843",	.data = (void *) 7843 },
  	{ .compatible = "ti,ads7845",	.data = (void *) 7845 },
  	{ .compatible = "ti,ads7846",	.data = (void *) 7846 },
  	{ .compatible = "ti,ads7873",	.data = (void *) 7873 },
  	{ }
  };
  MODULE_DEVICE_TABLE(of, ads7846_dt_ids);
  
  static const struct ads7846_platform_data *ads7846_probe_dt(struct device *dev)
  {
  	struct ads7846_platform_data *pdata;
  	struct device_node *node = dev->of_node;
  	const struct of_device_id *match;
  
  	if (!node) {
  		dev_err(dev, "Device does not have associated DT data
  ");
  		return ERR_PTR(-EINVAL);
  	}
  
  	match = of_match_device(ads7846_dt_ids, dev);
  	if (!match) {
  		dev_err(dev, "Unknown device model
  ");
  		return ERR_PTR(-EINVAL);
  	}
  
  	pdata = devm_kzalloc(dev, sizeof(*pdata), GFP_KERNEL);
  	if (!pdata)
  		return ERR_PTR(-ENOMEM);
  
  	pdata->model = (unsigned long)match->data;
  
  	of_property_read_u16(node, "ti,vref-delay-usecs",
  			     &pdata->vref_delay_usecs);
  	of_property_read_u16(node, "ti,vref-mv", &pdata->vref_mv);
  	pdata->keep_vref_on = of_property_read_bool(node, "ti,keep-vref-on");
  
  	pdata->swap_xy = of_property_read_bool(node, "ti,swap-xy");
  
  	of_property_read_u16(node, "ti,settle-delay-usec",
  			     &pdata->settle_delay_usecs);
  	of_property_read_u16(node, "ti,penirq-recheck-delay-usecs",
  			     &pdata->penirq_recheck_delay_usecs);
  
  	of_property_read_u16(node, "ti,x-plate-ohms", &pdata->x_plate_ohms);
  	of_property_read_u16(node, "ti,y-plate-ohms", &pdata->y_plate_ohms);
  
  	of_property_read_u16(node, "ti,x-min", &pdata->x_min);
  	of_property_read_u16(node, "ti,y-min", &pdata->y_min);
  	of_property_read_u16(node, "ti,x-max", &pdata->x_max);
  	of_property_read_u16(node, "ti,y-max", &pdata->y_max);
  
  	of_property_read_u16(node, "ti,pressure-min", &pdata->pressure_min);
  	of_property_read_u16(node, "ti,pressure-max", &pdata->pressure_max);
  
  	of_property_read_u16(node, "ti,debounce-max", &pdata->debounce_max);
  	of_property_read_u16(node, "ti,debounce-tol", &pdata->debounce_tol);
  	of_property_read_u16(node, "ti,debounce-rep", &pdata->debounce_rep);
  
  	of_property_read_u32(node, "ti,pendown-gpio-debounce",
  			     &pdata->gpio_pendown_debounce);
  
  	pdata->wakeup = of_property_read_bool(node, "linux,wakeup");
  
  	pdata->gpio_pendown = of_get_named_gpio(dev->of_node, "pendown-gpio", 0);
  
  	return pdata;
  }
  #else
  static const struct ads7846_platform_data *ads7846_probe_dt(struct device *dev)
  {
  	dev_err(dev, "no platform data defined
  ");
  	return ERR_PTR(-EINVAL);
  }
  #endif
  
  static int ads7846_probe(struct spi_device *spi)
  {
  	const struct ads7846_platform_data *pdata;
  	struct ads7846 *ts;
  	struct ads7846_packet *packet;
  	struct input_dev *input_dev;
  	unsigned long irq_flags;
  	int err;
  
  	if (!spi->irq) {
  		dev_dbg(&spi->dev, "no IRQ?
  ");
  		return -EINVAL;
  	}
  
  	/* don't exceed max specified sample rate */
  	if (spi->max_speed_hz > (125000 * SAMPLE_BITS)) {
  		dev_err(&spi->dev, "f(sample) %d KHz?
  ",
  				(spi->max_speed_hz/SAMPLE_BITS)/1000);
  		return -EINVAL;
  	}
  
  	/*
  	 * We'd set TX word size 8 bits and RX word size to 13 bits ... except
  	 * that even if the hardware can do that, the SPI controller driver
  	 * may not.  So we stick to very-portable 8 bit words, both RX and TX.
  	 */
  	spi->bits_per_word = 8;
  	spi->mode = SPI_MODE_0;
  	err = spi_setup(spi);
  	if (err < 0)
  		return err;
  
  	ts = kzalloc(sizeof(struct ads7846), GFP_KERNEL);
  	packet = kzalloc(sizeof(struct ads7846_packet), GFP_KERNEL);
  	input_dev = input_allocate_device();
  	if (!ts || !packet || !input_dev) {
  		err = -ENOMEM;
  		goto err_free_mem;
  	}
  
  	spi_set_drvdata(spi, ts);
  
  	ts->packet = packet;
  	ts->spi = spi;
  	ts->input = input_dev;
  
  	mutex_init(&ts->lock);
  	init_waitqueue_head(&ts->wait);
  
  	pdata = dev_get_platdata(&spi->dev);
  	if (!pdata) {
  		pdata = ads7846_probe_dt(&spi->dev);
  		if (IS_ERR(pdata))
  			return PTR_ERR(pdata);
  	}
  
  	ts->model = pdata->model ? : 7846;
  	ts->vref_delay_usecs = pdata->vref_delay_usecs ? : 100;
  	ts->x_plate_ohms = pdata->x_plate_ohms ? : 400;
  	ts->pressure_max = pdata->pressure_max ? : ~0;
  
  	ts->vref_mv = pdata->vref_mv;
  	ts->swap_xy = pdata->swap_xy;
  
  	if (pdata->filter != NULL) {
  		if (pdata->filter_init != NULL) {
  			err = pdata->filter_init(pdata, &ts->filter_data);
  			if (err < 0)
  				goto err_free_mem;
  		}
  		ts->filter = pdata->filter;
  		ts->filter_cleanup = pdata->filter_cleanup;
  	} else if (pdata->debounce_max) {
  		ts->debounce_max = pdata->debounce_max;
  		if (ts->debounce_max < 2)
  			ts->debounce_max = 2;
  		ts->debounce_tol = pdata->debounce_tol;
  		ts->debounce_rep = pdata->debounce_rep;
  		ts->filter = ads7846_debounce_filter;
  		ts->filter_data = ts;
  	} else {
  		ts->filter = ads7846_no_filter;
  	}
  
  	err = ads7846_setup_pendown(spi, ts, pdata);
  	if (err)
  		goto err_cleanup_filter;
  
  	if (pdata->penirq_recheck_delay_usecs)
  		ts->penirq_recheck_delay_usecs =
  				pdata->penirq_recheck_delay_usecs;
  
  	ts->wait_for_sync = pdata->wait_for_sync ? : null_wait_for_sync;
  
  	snprintf(ts->phys, sizeof(ts->phys), "%s/input0", dev_name(&spi->dev));
  	snprintf(ts->name, sizeof(ts->name), "ADS%d Touchscreen", ts->model);
  
  	input_dev->name = ts->name;
  	input_dev->phys = ts->phys;
  	input_dev->dev.parent = &spi->dev;
  
  	input_dev->evbit[0] = BIT_MASK(EV_KEY) | BIT_MASK(EV_ABS);
  	input_dev->keybit[BIT_WORD(BTN_TOUCH)] = BIT_MASK(BTN_TOUCH);
  	input_set_abs_params(input_dev, ABS_X,
  			pdata->x_min ? : 0,
  			pdata->x_max ? : MAX_12BIT,
  			0, 0);
  	input_set_abs_params(input_dev, ABS_Y,
  			pdata->y_min ? : 0,
  			pdata->y_max ? : MAX_12BIT,
  			0, 0);
  	input_set_abs_params(input_dev, ABS_PRESSURE,
  			pdata->pressure_min, pdata->pressure_max, 0, 0);
  
  	ads7846_setup_spi_msg(ts, pdata);
  
  	ts->reg = regulator_get(&spi->dev, "vcc");
  	if (IS_ERR(ts->reg)) {
  		err = PTR_ERR(ts->reg);
  		dev_err(&spi->dev, "unable to get regulator: %d
  ", err);
  		goto err_free_gpio;
  	}
  
  	err = regulator_enable(ts->reg);
  	if (err) {
  		dev_err(&spi->dev, "unable to enable regulator: %d
  ", err);
  		goto err_put_regulator;
  	}
  
  	irq_flags = pdata->irq_flags ? : IRQF_TRIGGER_FALLING;
  	irq_flags |= IRQF_ONESHOT;
  
  	err = request_threaded_irq(spi->irq, ads7846_hard_irq, ads7846_irq,
  				   irq_flags, spi->dev.driver->name, ts);
  	if (err && !pdata->irq_flags) {
  		dev_info(&spi->dev,
  			"trying pin change workaround on irq %d
  ", spi->irq);
  		irq_flags |= IRQF_TRIGGER_RISING;
  		err = request_threaded_irq(spi->irq,
  				  ads7846_hard_irq, ads7846_irq,
  				  irq_flags, spi->dev.driver->name, ts);
  	}
  
  	if (err) {
  		dev_dbg(&spi->dev, "irq %d busy?
  ", spi->irq);
  		goto err_disable_regulator;
  	}
  
  	err = ads784x_hwmon_register(spi, ts);
  	if (err)
  		goto err_free_irq;
  
  	dev_info(&spi->dev, "touchscreen, irq %d
  ", spi->irq);
  
  	/*
  	 * Take a first sample, leaving nPENIRQ active and vREF off; avoid
  	 * the touchscreen, in case it's not connected.
  	 */
  	if (ts->model == 7845)
  		ads7845_read12_ser(&spi->dev, PWRDOWN);
  	else
  		(void) ads7846_read12_ser(&spi->dev, READ_12BIT_SER(vaux));
  
  	err = sysfs_create_group(&spi->dev.kobj, &ads784x_attr_group);
  	if (err)
  		goto err_remove_hwmon;
  
  	err = input_register_device(input_dev);
  	if (err)
  		goto err_remove_attr_group;
  
  	device_init_wakeup(&spi->dev, pdata->wakeup);
  
  	/*
  	 * If device does not carry platform data we must have allocated it
  	 * when parsing DT data.
  	 */
  	if (!dev_get_platdata(&spi->dev))
  		devm_kfree(&spi->dev, (void *)pdata);
  
  	return 0;
  
   err_remove_attr_group:
  	sysfs_remove_group(&spi->dev.kobj, &ads784x_attr_group);
   err_remove_hwmon:
  	ads784x_hwmon_unregister(spi, ts);
   err_free_irq:
  	free_irq(spi->irq, ts);
   err_disable_regulator:
  	regulator_disable(ts->reg);
   err_put_regulator:
  	regulator_put(ts->reg);
   err_free_gpio:
  	if (!ts->get_pendown_state)
  		gpio_free(ts->gpio_pendown);
   err_cleanup_filter:
  	if (ts->filter_cleanup)
  		ts->filter_cleanup(ts->filter_data);
   err_free_mem:
  	input_free_device(input_dev);
  	kfree(packet);
  	kfree(ts);
  	return err;
  }
  
  static int ads7846_remove(struct spi_device *spi)
  {
  	struct ads7846 *ts = spi_get_drvdata(spi);
  
  	device_init_wakeup(&spi->dev, false);
  
  	sysfs_remove_group(&spi->dev.kobj, &ads784x_attr_group);
  
  	ads7846_disable(ts);
  	free_irq(ts->spi->irq, ts);
  
  	input_unregister_device(ts->input);
  
  	ads784x_hwmon_unregister(spi, ts);
  
  	regulator_disable(ts->reg);
  	regulator_put(ts->reg);
  
  	if (!ts->get_pendown_state) {
  		/*
  		 * If we are not using specialized pendown method we must
  		 * have been relying on gpio we set up ourselves.
  		 */
  		gpio_free(ts->gpio_pendown);
  	}
  
  	if (ts->filter_cleanup)
  		ts->filter_cleanup(ts->filter_data);
  
  	kfree(ts->packet);
  	kfree(ts);
  
  	dev_dbg(&spi->dev, "unregistered touchscreen
  ");
  
  	return 0;
  }
  
  static struct spi_driver ads7846_driver = {
  	.driver = {
  		.name	= "ads7846",
  		.owner	= THIS_MODULE,
  		.pm	= &ads7846_pm,
  		.of_match_table = of_match_ptr(ads7846_dt_ids),
  	},
  	.probe		= ads7846_probe,
  	.remove		= ads7846_remove,
  };
  
  module_spi_driver(ads7846_driver);
  
  MODULE_DESCRIPTION("ADS7846 TouchScreen Driver");
  MODULE_LICENSE("GPL");
  MODULE_ALIAS("spi:ads7846");