Merge tag 'trace-v7.3-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-tracegrafted

Pull tracing fixes from Steven Rostedt:

 - Don't destroy user event fields when removal fails

   User event fields are destroyed before the event is removed from
   visibility. But that can fail leaving the still visible event with no
   fields. Move the destroying of the fields to after the event is
   successfully removed from visibility.

 - Initialize function graph state is fork before calling
   copy_exec_state()

   For non-CLONE_VM forks, copy_exec_state() allocates a new
   task_exec_state. If that allocation fails, ftrace_graph_exit_task()
   will free the tasks ret_stack pointer. Since that pointer is still
   using the parent's ret_stack, it mistakenly frees the parent's
   pointer too.

   Call ftrace_graph_init() on the task first which will NULL out the
   new tasks's ret_stack and if the copy fails, it will not free
   anything.

 - Remove FGRAPH_MAX_INDEX

   The macro FGRAPH_MAX_INDEX was added but never used. Remove it.

 - Save ent_size in function graph printing of nested functions

   The function graph tracer needs to look at the next event to see if
   the next event is the return of the current function entry. If it is,
   it prints a single line:

	ktime_get();

   Otherwise it prints it like a nested function:

	tick_nohz_irq_exit() {
	    ktime_get();
	    kcpustat_irq_exit();
	}

   In order to look at the next event, it must save the current event so
   that it has the information to print from it. It saves the event in
   the iterator descriptor called "ent". What it doesn't save is the
   ent_size of the event which is now used to know if the function graph
   arguments are to be printed. The peek doesn't save the size so the
   size used happens to be that of the size of the last event that was
   seen.

   Save the entry event size in the iterator descriptor so that the
   correct size is used.

 - Fix several errors with freeing data in the histogram code

   The histogram code had a lot of leaked or or incorrect accounting
   when failures happen. Correct them.

 - Fix histogram regression of .percent and .graph modifiers

   Up until 6.3 histogram values could have "percent" or "graph"
   modifiers that changed how they were printed. But a change that added
   restricting histograms values from being strings, stack traces and
   other modifiers inadvertently prevented them from using the percent
   and graph modifiers, which were legal use cases for values.

   Put back the percent and graph modifiers.

 - Fix various typos in the comments

 - Set the trace_clock before initializing a histogram with clock
   argument

   The histogram API allows the user to specific which trace clock to
   use via a "clock=" string. The histogram is set up first before the
   clock is checked. If the passed in clock is not valid, it exits
   without fully fixing up the histogram leaving it on the list and a
   use-after-free can trigger.

   Update the clock argument first and if it fails then exit gracefully
   before the histogram trigger is placed on any lists.

 - Restore :mod: trailer after parsing in ftrace_set_clr_event

   The function ftrace_set_clr_event() modifies the parse string and
   needs to put it back to what was passed in. It searches for ":mod:"
   via a strsep() but fails to put back the first ':' in the string.

   Add back the ':' in the passed in string.

 - Take trace_array reference when opening a tracer options file

   The options files are dynamically created and some tracers add their
   own options. When a tracer adds their own list of options, the
   trace_array holding them has an array to hold the list of options for
   each tracer. This array increases in size via a krealloc(), and the
   new entry gets a newly allocated array to hold the options of the new
   tracer being added.

   The element in each entry of the tracer's option array holds a
   pointer back to the trace_array, a pointer to the tracer it is
   associated to, a pointer to the flags of the option.

   The issue is that these arrays are freed when the trace_array is
   freed when its instance it represents is removed from the instances
   directory. There's a race that an open of one of these options files
   can happen when the instance is being removed.

   Add a new helper function to be called by the open function of the
   options file to iterate all existing trace_arrays under a lock and
   find the one that has the given option element in one of it's tracer
   arrays. If found, then update the associated trace_array's reference
   counter to keep it from being freed. If not found, have the open call
   return -ENODEV.

 - Disable interrupts when acquiring the lock in rb_wake_up_waiters()

   The function rb_wake_up_waiters() assumes it will be called in
   interrupt context and does not disable irqs when taking
   cpu_buffer->reader_lock, which can be called in hard interrupt
   context. The issue is in PREEMPT_RT, this function is called in
   thread context leaving this lock open to a deadlock.

   Take the lock with interrupts disabled.

 - Use rcu_assign_pointer() for tmp_ops filter hash

   The tmp_ops used in update_ftrace_direct_mod() assigns its
   filter_hash field directly, but that field is annotated as __rcu and
   sparse complains. Assign it with rcu_assign_pointer()

 - Fix use-after-free in enable_trigger_private_data_free()

   The trace_event_call is accessed through the event_trigger_data's
   trace_event_file pointer to put the trace_event_call on freeing. The
   issue is that the trace_event_file data may have been freed already
   causing a use-after-free. Add a field to the event_trigger_data that
   points directly to the trace_event_call so that it can decrement its
   reference directly without needing to go through the
   trace_event_file.

 - Fix accounting of buffer data remote headers

   trace_buffer_desc_size() and trace_remote_alloc_buffer() undercount
   the number of pages is needed for the asked for size as it doesn't
   take into account the meta data on each page. Add a helper function
   to do the calculation properly and use that in these functions.

 - Catch nr_page_va overflow in ring_buffer_desc sizing

   The number of pages per remote ring buffer is capped by
   ring_buffer_desc::nr_page_va (32 bits). A buffer_size large enough to
   overflow that field would silently allocate a descriptor smaller than
   what was asked for.

 - Do not resize the subbuf order if any per_cpu buffer is disabled

   The mmapping of ring buffers disables resizing the subbuffers, but it
   is done per-cpu whereas the subbuf size change is done for all the
   per_cpu buffers under the buffer->mutex. It could change the size of
   some while the mapping is happening on others. Have the resize of the
   subbuf order check all the per_cpu buffers under the lock to see if
   any of them is disabled before starting and causing an inconsistency
   between buffers that are being mapped.

* tag 'trace-v7.3-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace: (25 commits)
  ring-buffer: Check resize_disabled before publishing the new subbuf order
  tracing/remotes: Catch nr_page_va overflow in ring_buffer_desc sizing
  tracing/remotes: Account for ring buffer page header in size calculation
  tracing: Don't dereference trace_event_file in deferred trigger free
  ftrace: Use rcu_assign_pointer() for tmp_ops filter hash
  ring-buffer: Acquire the lock with irqsave in rb_wake_up_waiters()
  tracing: Take trace_array reference when opening a tracer options file
  tracing: Fix ring_buffer_read_page_size() kernel-doc
  tracing: Restore :mod: trailer after parsing in ftrace_set_clr_event()
  tracing: Fix memory corruption from a "STACKTRACE" histogram key
  tracing: Fix memory corruption from the histogram stacktrace modifier
  tracing: Undo the registration when enabling the histogram trigger fails
  tracing: Take the reference before publishing the named histogram trigger
  tracing: Set the trace clock before registering the histogram trigger
  tracing: Fix typo "preceeded" in comment
  tracing: Fix typo "availabe" in comment
  tracing: Let histogram values keep the percent and graph modifiers
  tracing: Keep the entry count when the histogram stats allocation fails
  tracing: Free histogram the field rejected for a bad modifier
  tracing: Free histogram the var ref when its initialization fails
  ...

1 files changed, 1589 insertions, 0 deletions

diff --git a/drivers/input/touchscreen/ads7846.c b/drivers/input/touchscreen/ads7846.c
new file mode 100644
index 000000000..8d6416ac2
--- /dev/null
+++ b/drivers/input/touchscreen/ads7846.c
@@ -0,0 +1,1589 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * 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
+ */
+#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/input/touchscreen.h>
+#include <linux/interrupt.h>
+#include <linux/slab.h>
+#include <linux/pm.h>
+#include <linux/property.h>
+#include <linux/gpio/consumer.h>
+#include <linux/spi/spi.h>
+#include <linux/spi/ads7846.h>
+#include <linux/regulator/consumer.h>
+#include <linux/module.h>
+#include <linux/unaligned.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 ads7846_buf {
+	u8 cmd;
+	__be16 data;
+} __packed;
+
+struct ads7846_buf_layout {
+	unsigned int offset;
+	unsigned int count;
+	unsigned int skip;
+};
+
+/*
+ * 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 {
+	unsigned int count;
+	unsigned int count_skip;
+	unsigned int cmds;
+	unsigned int last_cmd_idx;
+	struct ads7846_buf_layout l[5];
+	struct ads7846_buf *rx;
+	struct ads7846_buf *tx;
+
+	struct ads7846_buf pwrdown_cmd;
+
+	bool ignore;
+	u16 x, y, z1, z2;
+};
+
+struct ads7846 {
+	struct input_dev	*input;
+	char			phys[32];
+	char			name[32];
+
+	struct spi_device	*spi;
+	struct regulator	*reg;
+
+	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 touchscreen_properties core_prop;
+
+	struct mutex		lock;
+	bool			stopped;	/* P: lock */
+	bool			disabled;	/* P: lock */
+	bool			suspended;	/* P: lock */
+
+	int			(*setup_spi_msg)(struct ads7846 *ts,
+					const struct ads7846_platform_data *pdata);
+	void			(*read_state)(struct ads7846 *ts);
+	int			(*filter)(void *data, int data_idx, int *val);
+	void			*filter_data;
+	int			(*get_pendown_state)(void);
+	struct gpio_desc	*gpio_pendown;
+	struct gpio_desc	*gpio_hsync;
+
+	void			(*wait_for_sync)(void);
+};
+
+enum ads7846_filter {
+	ADS7846_FILTER_OK,
+	ADS7846_FILTER_REPEAT,
+	ADS7846_FILTER_IGNORE,
+};
+
+/* 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))
+
+/* Order commands in the most optimal way to reduce Vref switching and
+ * settling time:
+ * Measure:  X; Vref: X+, X-; IN: Y+
+ * Measure:  Y; Vref: Y+, Y-; IN: X+
+ * Measure: Z1; Vref: Y+, X-; IN: X+
+ * Measure: Z2; Vref: Y+, X-; IN: Y-
+ */
+enum ads7846_cmds {
+	ADS7846_X,
+	ADS7846_Y,
+	ADS7846_Z1,
+	ADS7846_Z2,
+	ADS7846_PWDOWN,
+};
+
+static int get_pendown_state(struct ads7846 *ts)
+{
+	if (ts->get_pendown_state)
+		return ts->get_pendown_state();
+
+	return gpiod_get_value(ts->gpio_pendown);
+}
+
+static void ads7846_report_pen_up(struct ads7846 *ts)
+{
+	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\n");
+}
+
+/* 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) {
+		/* Check if pen was released since last stop */
+		if (ts->pendown && !get_pendown_state(ts))
+			ads7846_report_pen_up(ts);
+
+		/* 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\n", error);
+
+	ads7846_restart(ts);
+}
+
+static void ads7846_disable(struct ads7846 *ts)
+{
+	guard(mutex)(&ts->lock);
+
+	if (!ts->disabled) {
+
+		if  (!ts->suspended)
+			__ads7846_disable(ts);
+
+		ts->disabled = true;
+	}
+}
+
+static void ads7846_enable(struct ads7846 *ts)
+{
+	guard(mutex)(&ts->lock);
+
+	if (ts->disabled) {
+
+		ts->disabled = false;
+
+		if (!ts->suspended)
+			__ads7846_enable(ts);
+	}
+}
+
+/*--------------------------------------------------------------------------*/
+
+/*
+ * 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;
+	struct spi_message	msg;
+	struct spi_transfer	xfer[8];
+	/*
+	 * DMA (thus cache coherency maintenance) requires the
+	 * transfer buffers to live in their own cache lines.
+	 */
+	__be16 sample ____cacheline_aligned;
+	u16			scratch;
+};
+
+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);
+	int status;
+
+	struct ser_req *req __free(kfree) = kzalloc_obj(*req);
+	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.value = ts->vref_delay_usecs;
+		req->xfer[1].delay.unit = SPI_DELAY_UNIT_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;
+	spi_message_add_tail(&req->xfer[5], &req->msg);
+
+	/* clear the command register */
+	req->xfer[6].rx_buf = &req->scratch;
+	req->xfer[6].len = 1;
+	spi_message_add_tail(&req->xfer[6], &req->msg);
+
+	req->xfer[7].rx_buf = &req->scratch;
+	req->xfer[7].len = 2;
+	CS_CHANGE(req->xfer[7]);
+	spi_message_add_tail(&req->xfer[7], &req->msg);
+
+	scoped_guard(mutex, &ts->lock) {
+		ads7846_stop(ts);
+		status = spi_sync(spi, &req->msg);
+		ads7846_restart(ts);
+	}
+
+	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;
+	}
+
+	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);
+	int status;
+
+	struct ads7845_ser_req *req __free(kfree) = kzalloc_obj(*req);
+	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);
+
+	scoped_guard(mutex, &ts->lock) {
+		ads7846_stop(ts);
+		status = spi_sync(spi, &req->msg);
+		ads7846_restart(ts);
+	}
+
+	if (status == 0) {
+		/* BE12 value, then padding */
+		status = get_unaligned_be16(&req->sample[1]);
+		status = status >> 3;
+		status &= 0x0fff;
+	}
+
+	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(&ts->spi->dev, \
+			READ_12BIT_SER(var)); \
+	if (v < 0) \
+		return v; \
+	return sprintf(buf, "%u\n", 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 = kobj_to_dev(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 const 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)
+{
+	struct device *hwmon;
+
+	/* hwmon sensors need a reference voltage */
+	switch (ts->model) {
+	case 7846:
+		if (!ts->vref_mv) {
+			dev_dbg(&spi->dev, "assuming 2.5V internal vREF\n");
+			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\n",
+				ts->model);
+			return 0;
+		}
+		break;
+	}
+
+	hwmon = devm_hwmon_device_register_with_groups(&spi->dev,
+						       spi->modalias, ts,
+						       ads7846_attr_groups);
+
+	return PTR_ERR_OR_ZERO(hwmon);
+}
+
+#else
+static inline int ads784x_hwmon_register(struct spi_device *spi,
+					 struct ads7846 *ts)
+{
+	return 0;
+}
+#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\n", 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\n", 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_attrs[] = {
+	&dev_attr_pen_down.attr,
+	&dev_attr_disable.attr,
+	NULL,
+};
+ATTRIBUTE_GROUPS(ads784x);
+
+/*--------------------------------------------------------------------------*/
+
+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_buf *buf)
+{
+	int value;
+
+	value = be16_to_cpup(&buf->data);
+
+	/* enforce ADC output is 12 bits width */
+	return (value >> 3) & 0xfff;
+}
+
+static void ads7846_set_cmd_val(struct ads7846 *ts, enum ads7846_cmds cmd_idx,
+				u16 val)
+{
+	struct ads7846_packet *packet = ts->packet;
+
+	switch (cmd_idx) {
+	case ADS7846_Y:
+		packet->y = val;
+		break;
+	case ADS7846_X:
+		packet->x = val;
+		break;
+	case ADS7846_Z1:
+		packet->z1 = val;
+		break;
+	case ADS7846_Z2:
+		packet->z2 = val;
+		break;
+	default:
+		WARN_ON_ONCE(1);
+	}
+}
+
+static u8 ads7846_get_cmd(enum ads7846_cmds cmd_idx, int vref)
+{
+	switch (cmd_idx) {
+	case ADS7846_Y:
+		return READ_Y(vref);
+	case ADS7846_X:
+		return READ_X(vref);
+
+	/* 7846 specific commands  */
+	case ADS7846_Z1:
+		return READ_Z1(vref);
+	case ADS7846_Z2:
+		return READ_Z2(vref);
+	case ADS7846_PWDOWN:
+		return PWRDOWN;
+	default:
+		WARN_ON_ONCE(1);
+	}
+
+	return 0;
+}
+
+static bool ads7846_cmd_need_settle(enum ads7846_cmds cmd_idx)
+{
+	switch (cmd_idx) {
+	case ADS7846_X:
+	case ADS7846_Y:
+	case ADS7846_Z1:
+	case ADS7846_Z2:
+		return true;
+	case ADS7846_PWDOWN:
+		return false;
+	default:
+		WARN_ON_ONCE(1);
+	}
+
+	return false;
+}
+
+static int ads7846_filter(struct ads7846 *ts)
+{
+	struct ads7846_packet *packet = ts->packet;
+	int action;
+	int val;
+	unsigned int cmd_idx, b;
+
+	packet->ignore = false;
+	for (cmd_idx = packet->last_cmd_idx; cmd_idx < packet->cmds - 1; cmd_idx++) {
+		struct ads7846_buf_layout *l = &packet->l[cmd_idx];
+
+		packet->last_cmd_idx = cmd_idx;
+
+		for (b = l->skip; b < l->count; b++) {
+			val = ads7846_get_value(&packet->rx[l->offset + b]);
+
+			action = ts->filter(ts->filter_data, cmd_idx, &val);
+			if (action == ADS7846_FILTER_REPEAT) {
+				if (b == l->count - 1)
+					return -EAGAIN;
+			} else if (action == ADS7846_FILTER_OK) {
+				ads7846_set_cmd_val(ts, cmd_idx, val);
+				break;
+			} else {
+				packet->ignore = true;
+				return 0;
+			}
+		}
+	}
+
+	return 0;
+}
+
+static int ads7846_filter_one(struct ads7846 *ts, unsigned int cmd_idx)
+{
+	struct ads7846_packet *packet = ts->packet;
+	struct ads7846_buf_layout *l = &packet->l[cmd_idx];
+	int action, val;
+
+	val = ads7846_get_value(&packet->rx[l->offset + l->count - 1]);
+	action = ts->filter(ts->filter_data, cmd_idx, &val);
+	if (action == ADS7846_FILTER_REPEAT)
+		return -EAGAIN;
+	else if (action != ADS7846_FILTER_OK)
+		return -EIO;
+	ads7846_set_cmd_val(ts, cmd_idx, val);
+	return 0;
+}
+
+static void ads7846_wait_for_hsync(struct ads7846 *ts)
+{
+	if (ts->wait_for_sync) {
+		ts->wait_for_sync();
+		return;
+	}
+
+	if (!ts->gpio_hsync)
+		return;
+
+	/*
+	 * Wait for HSYNC to assert the line should be flagged
+	 * as active low so here we are waiting for it to assert
+	 */
+	while (!gpiod_get_value(ts->gpio_hsync))
+		cpu_relax();
+
+	/* Then we wait for it do de-assert */
+	while (gpiod_get_value(ts->gpio_hsync))
+		cpu_relax();
+}
+
+static void ads7846_halfd_read_state(struct ads7846 *ts)
+{
+	struct ads7846_packet *packet = ts->packet;
+	int msg_idx = 0;
+
+	packet->ignore = false;
+
+	while (msg_idx < ts->msg_count) {
+		int error;
+
+		ads7846_wait_for_hsync(ts);
+
+		error = spi_sync(ts->spi, &ts->msg[msg_idx]);
+		if (error) {
+			dev_err_ratelimited(&ts->spi->dev, "spi_sync --> %d\n",
+					    error);
+			packet->ignore = true;
+			return;
+		}
+
+		/*
+		 * Last message is power down request, no need to convert
+		 * or filter the value.
+		 */
+		if (msg_idx == ts->msg_count - 1)
+			break;
+
+		error = ads7846_filter_one(ts, msg_idx);
+		if (error == -EAGAIN) {
+			continue;
+		} else if (error) {
+			packet->ignore = true;
+			msg_idx = ts->msg_count - 1;
+		} else {
+			msg_idx++;
+		}
+	}
+}
+
+static void ads7846_read_state(struct ads7846 *ts)
+{
+	struct ads7846_packet *packet = ts->packet;
+	struct spi_message *m;
+	int msg_idx = 0;
+	int error;
+
+	packet->last_cmd_idx = 0;
+
+	while (true) {
+		ads7846_wait_for_hsync(ts);
+
+		m = &ts->msg[msg_idx];
+		error = spi_sync(ts->spi, m);
+		if (error) {
+			dev_err_ratelimited(&ts->spi->dev, "spi_sync --> %d\n", error);
+			packet->ignore = true;
+			return;
+		}
+
+		error = ads7846_filter(ts);
+		if (error)
+			continue;
+
+		return;
+	}
+}
+
+static void ads7846_report_state(struct ads7846 *ts)
+{
+	struct ads7846_packet *packet = ts->packet;
+	unsigned int Rt;
+	u16 x, y, z1, z2;
+
+	x = packet->x;
+	y = packet->y;
+	if (ts->model == 7845) {
+		z1 = 0;
+		z2 = 0;
+	} else {
+		z1 = packet->z1;
+		z2 = packet->z2;
+	}
+
+	/* range filtering */
+	if (x == MAX_12BIT)
+		x = 0;
+
+	if (ts->model == 7843 || ts->model == 7845) {
+		Rt = ts->pressure_max / 2;
+	} else if (likely(x && z1)) {
+		/* compute touch pressure resistance using equation #2 */
+		Rt = z2;
+		Rt -= z1;
+		Rt *= ts->x_plate_ohms;
+		Rt = DIV_ROUND_CLOSEST(Rt, 16);
+		Rt *= x;
+		Rt /= z1;
+		Rt = DIV_ROUND_CLOSEST(Rt, 256);
+	} 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->ignore || Rt > ts->pressure_max) {
+		dev_vdbg(&ts->spi->dev, "ignored %d pressure %d\n",
+			 packet->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->pendown) {
+			input_report_key(input, BTN_TOUCH, 1);
+			ts->pendown = true;
+			dev_vdbg(&ts->spi->dev, "DOWN\n");
+		}
+
+		touchscreen_report_pos(input, &ts->core_prop, x, y, false);
+		input_report_abs(input, ABS_PRESSURE, ts->pressure_max - Rt);
+
+		input_sync(input);
+		dev_vdbg(&ts->spi->dev, "%4d/%4d/%4d\n", 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 */
+		ts->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 && !ts->stopped)
+		ads7846_report_pen_up(ts);
+
+	return IRQ_HANDLED;
+}
+
+static int ads7846_suspend(struct device *dev)
+{
+	struct ads7846 *ts = dev_get_drvdata(dev);
+
+	guard(mutex)(&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;
+	}
+
+	return 0;
+}
+
+static int ads7846_resume(struct device *dev)
+{
+	struct ads7846 *ts = dev_get_drvdata(dev);
+
+	guard(mutex)(&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);
+	}
+
+	return 0;
+}
+
+static DEFINE_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)
+{
+	/*
+	 * 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 {
+		ts->gpio_pendown = devm_gpiod_get(&spi->dev, "pendown", GPIOD_IN);
+		if (IS_ERR(ts->gpio_pendown)) {
+			dev_err(&spi->dev, "failed to request pendown GPIO\n");
+			return PTR_ERR(ts->gpio_pendown);
+		}
+		if (pdata->gpio_pendown_debounce)
+			gpiod_set_debounce(ts->gpio_pendown,
+					   pdata->gpio_pendown_debounce);
+	}
+
+	return 0;
+}
+
+/*
+ * Set up the transfers to read touchscreen state; this assumes we
+ * use formula #2 for pressure, not #3.
+ */
+static int ads7846_halfd_spi_msg(struct ads7846 *ts,
+				 const struct ads7846_platform_data *pdata)
+{
+	struct spi_message *m = ts->msg;
+	struct spi_transfer *x = ts->xfer;
+	struct ads7846_packet *packet = ts->packet;
+	int vref = pdata->keep_vref_on;
+	unsigned int offset = 0;
+	unsigned int cmd_idx, b;
+	size_t size = 0;
+
+	if (pdata->settle_delay_usecs)
+		packet->count = 2;
+	else
+		packet->count = 1;
+
+	if (ts->model == 7846)
+		packet->cmds = 5; /* x, y, z1, z2, pwdown */
+	else
+		packet->cmds = 3; /* x, y, pwdown */
+
+	for (cmd_idx = 0; cmd_idx < packet->cmds; cmd_idx++) {
+		struct ads7846_buf_layout *l = &packet->l[cmd_idx];
+		unsigned int max_count;
+
+		if (cmd_idx == packet->cmds - 1) {
+			cmd_idx = ADS7846_PWDOWN;
+			max_count = 1;
+		} else {
+			max_count = packet->count;
+		}
+
+		l->offset = offset;
+		offset += max_count;
+		l->count = max_count;
+		l->skip = 0;
+		size += sizeof(*packet->rx) * max_count;
+	}
+
+	/* We use two transfers per command. */
+	if (ARRAY_SIZE(ts->xfer) < offset * 2)
+		return -ENOMEM;
+
+	packet->rx = devm_kzalloc(&ts->spi->dev, size, GFP_KERNEL);
+	if (!packet->rx)
+		return -ENOMEM;
+
+	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 = 0;
+
+	for (cmd_idx = 0; cmd_idx < packet->cmds; cmd_idx++) {
+		struct ads7846_buf_layout *l = &packet->l[cmd_idx];
+		u8 cmd;
+
+		ts->msg_count++;
+		spi_message_init(m);
+		m->context = ts;
+
+		if (cmd_idx == packet->cmds - 1)
+			cmd_idx = ADS7846_PWDOWN;
+
+		cmd = ads7846_get_cmd(cmd_idx, vref);
+
+		for (b = 0; b < l->count; b++) {
+			packet->rx[l->offset + b].cmd = cmd;
+			x->tx_buf = &packet->rx[l->offset + b].cmd;
+			x->len = 1;
+			spi_message_add_tail(x, m);
+			x++;
+			x->rx_buf = &packet->rx[l->offset + b].data;
+			x->len = 2;
+			if (b < l->count - 1 && l->count > 1) {
+				x->delay.value = pdata->settle_delay_usecs;
+				x->delay.unit = SPI_DELAY_UNIT_USECS;
+			}
+			spi_message_add_tail(x, m);
+			x++;
+		}
+		m++;
+	}
+	return 0;
+}
+
+/*
+ * Set up the transfers to read touchscreen state; this assumes we
+ * use formula #2 for pressure, not #3.
+ */
+static int 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;
+	unsigned int count, offset = 0;
+	unsigned int cmd_idx, b;
+	unsigned long time;
+	size_t size = 0;
+
+	/* time per bit */
+	time = NSEC_PER_SEC / ts->spi->max_speed_hz;
+
+	count = pdata->settle_delay_usecs * NSEC_PER_USEC / time;
+	packet->count_skip = DIV_ROUND_UP(count, 24);
+
+	if (ts->debounce_max && ts->debounce_rep)
+		/* ads7846_debounce_filter() is making ts->debounce_rep + 2
+		 * reads. So we need to get all samples for normal case. */
+		packet->count = ts->debounce_rep + 2;
+	else
+		packet->count = 1;
+
+	if (ts->model == 7846)
+		packet->cmds = 5; /* x, y, z1, z2, pwdown */
+	else
+		packet->cmds = 3; /* x, y, pwdown */
+
+	for (cmd_idx = 0; cmd_idx < packet->cmds; cmd_idx++) {
+		struct ads7846_buf_layout *l = &packet->l[cmd_idx];
+		unsigned int max_count;
+
+		if (cmd_idx == packet->cmds - 1)
+			cmd_idx = ADS7846_PWDOWN;
+
+		if (ads7846_cmd_need_settle(cmd_idx))
+			max_count = packet->count + packet->count_skip;
+		else
+			max_count = packet->count;
+
+		l->offset = offset;
+		offset += max_count;
+		l->count = max_count;
+		l->skip = packet->count_skip;
+		size += sizeof(*packet->tx) * max_count;
+	}
+
+	packet->tx = devm_kzalloc(&ts->spi->dev, size, GFP_KERNEL);
+	if (!packet->tx)
+		return -ENOMEM;
+
+	packet->rx = devm_kzalloc(&ts->spi->dev, size, GFP_KERNEL);
+	if (!packet->rx)
+		return -ENOMEM;
+
+	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;
+
+	for (cmd_idx = 0; cmd_idx < packet->cmds; cmd_idx++) {
+		struct ads7846_buf_layout *l = &packet->l[cmd_idx];
+		u8 cmd;
+
+		if (cmd_idx == packet->cmds - 1)
+			cmd_idx = ADS7846_PWDOWN;
+
+		cmd = ads7846_get_cmd(cmd_idx, vref);
+
+		for (b = 0; b < l->count; b++)
+			packet->tx[l->offset + b].cmd = cmd;
+	}
+
+	x->tx_buf = packet->tx;
+	x->rx_buf = packet->rx;
+	x->len = size;
+	spi_message_add_tail(x, m);
+
+	return 0;
+}
+
+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 spi_device_id ads7846_spi_ids[] = {
+	{ "tsc2046", 7846 },
+	{ "ads7843", 7843 },
+	{ "ads7845", 7845 },
+	{ "ads7846", 7846 },
+	{ "ads7873", 7873 },
+	{ },
+};
+MODULE_DEVICE_TABLE(spi, ads7846_spi_ids);
+
+static const struct ads7846_platform_data *ads7846_get_props(struct device *dev)
+{
+	struct ads7846_platform_data *pdata;
+	u32 value;
+
+	pdata = devm_kzalloc(dev, sizeof(*pdata), GFP_KERNEL);
+	if (!pdata)
+		return ERR_PTR(-ENOMEM);
+
+	pdata->model = (uintptr_t)device_get_match_data(dev);
+
+	device_property_read_u16(dev, "ti,vref-delay-usecs",
+				 &pdata->vref_delay_usecs);
+	device_property_read_u16(dev, "ti,vref-mv", &pdata->vref_mv);
+	pdata->keep_vref_on = device_property_read_bool(dev, "ti,keep-vref-on");
+
+	pdata->swap_xy = device_property_read_bool(dev, "ti,swap-xy");
+
+	device_property_read_u16(dev, "ti,settle-delay-usec",
+				 &pdata->settle_delay_usecs);
+	device_property_read_u16(dev, "ti,penirq-recheck-delay-usecs",
+				 &pdata->penirq_recheck_delay_usecs);
+
+	device_property_read_u16(dev, "ti,x-plate-ohms", &pdata->x_plate_ohms);
+	device_property_read_u16(dev, "ti,y-plate-ohms", &pdata->y_plate_ohms);
+
+	device_property_read_u16(dev, "ti,x-min", &pdata->x_min);
+	device_property_read_u16(dev, "ti,y-min", &pdata->y_min);
+	device_property_read_u16(dev, "ti,x-max", &pdata->x_max);
+	device_property_read_u16(dev, "ti,y-max", &pdata->y_max);
+
+	/*
+	 * touchscreen-max-pressure gets parsed during
+	 * touchscreen_parse_properties()
+	 */
+	device_property_read_u16(dev, "ti,pressure-min", &pdata->pressure_min);
+	if (!device_property_read_u32(dev, "touchscreen-min-pressure", &value))
+		pdata->pressure_min = (u16) value;
+	device_property_read_u16(dev, "ti,pressure-max", &pdata->pressure_max);
+
+	device_property_read_u16(dev, "ti,debounce-max", &pdata->debounce_max);
+	if (!device_property_read_u32(dev, "touchscreen-average-samples", &value))
+		pdata->debounce_max = (u16) value;
+	device_property_read_u16(dev, "ti,debounce-tol", &pdata->debounce_tol);
+	device_property_read_u16(dev, "ti,debounce-rep", &pdata->debounce_rep);
+
+	device_property_read_u32(dev, "ti,pendown-gpio-debounce",
+			     &pdata->gpio_pendown_debounce);
+
+	pdata->wakeup = device_property_read_bool(dev, "wakeup-source") ||
+			device_property_read_bool(dev, "linux,wakeup");
+
+	return pdata;
+}
+
+static void ads7846_regulator_disable(void *regulator)
+{
+	regulator_disable(regulator);
+}
+
+static int ads7846_probe(struct spi_device *spi)
+{
+	const struct ads7846_platform_data *pdata;
+	struct ads7846 *ts;
+	struct device *dev = &spi->dev;
+	struct ads7846_packet *packet;
+	struct input_dev *input_dev;
+	unsigned long irq_flags;
+	int err;
+
+	if (!spi->irq) {
+		dev_dbg(dev, "no IRQ?\n");
+		return -EINVAL;
+	}
+
+	/* don't exceed max specified sample rate */
+	if (spi->max_speed_hz > (125000 * SAMPLE_BITS)) {
+		dev_err(dev, "f(sample) %d KHz?\n",
+			(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_X_MASK;
+	spi->mode |= SPI_MODE_0;
+	err = spi_setup(spi);
+	if (err < 0)
+		return err;
+
+	ts = devm_kzalloc(dev, sizeof(struct ads7846), GFP_KERNEL);
+	if (!ts)
+		return -ENOMEM;
+
+	if (spi->controller->flags & SPI_CONTROLLER_HALF_DUPLEX) {
+		ts->setup_spi_msg = ads7846_halfd_spi_msg;
+		ts->read_state    = ads7846_halfd_read_state;
+	} else {
+		ts->setup_spi_msg = ads7846_setup_spi_msg;
+		ts->read_state    = ads7846_read_state;
+	}
+
+	packet = devm_kzalloc(dev, sizeof(struct ads7846_packet), GFP_KERNEL);
+	if (!packet)
+		return -ENOMEM;
+
+	input_dev = devm_input_allocate_device(dev);
+	if (!input_dev)
+		return -ENOMEM;
+
+	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(dev);
+	if (!pdata) {
+		pdata = ads7846_get_props(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->vref_mv = pdata->vref_mv;
+
+	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)
+		return err;
+
+	if (pdata->penirq_recheck_delay_usecs)
+		ts->penirq_recheck_delay_usecs =
+				pdata->penirq_recheck_delay_usecs;
+
+	ts->wait_for_sync = pdata->wait_for_sync;
+
+	ts->gpio_hsync = devm_gpiod_get_optional(dev, "ti,hsync", GPIOD_IN);
+	if (IS_ERR(ts->gpio_hsync))
+		return PTR_ERR(ts->gpio_hsync);
+
+	snprintf(ts->phys, sizeof(ts->phys), "%s/input0", dev_name(dev));
+	snprintf(ts->name, sizeof(ts->name), "ADS%d Touchscreen", ts->model);
+
+	input_dev->name = ts->name;
+	input_dev->phys = ts->phys;
+
+	input_dev->id.bustype = BUS_SPI;
+	input_dev->id.product = pdata->model;
+
+	input_set_capability(input_dev, EV_KEY, 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);
+	if (ts->model != 7845)
+		input_set_abs_params(input_dev, ABS_PRESSURE,
+				pdata->pressure_min, pdata->pressure_max, 0, 0);
+
+	/*
+	 * Parse common framework properties. Must be done here to ensure the
+	 * correct behaviour in case of using the legacy vendor bindings. The
+	 * general binding value overrides the vendor specific one.
+	 */
+	touchscreen_parse_properties(ts->input, false, &ts->core_prop);
+	ts->pressure_max = input_abs_get_max(input_dev, ABS_PRESSURE) ? : ~0;
+
+	/*
+	 * Check if legacy ti,swap-xy binding is used instead of
+	 * touchscreen-swapped-x-y
+	 */
+	if (!ts->core_prop.swap_x_y && pdata->swap_xy) {
+		swap(input_dev->absinfo[ABS_X], input_dev->absinfo[ABS_Y]);
+		ts->core_prop.swap_x_y = true;
+	}
+
+	err = ts->setup_spi_msg(ts, pdata);
+	if (err)
+		return err;
+
+	ts->reg = devm_regulator_get(dev, "vcc");
+	if (IS_ERR(ts->reg)) {
+		err = PTR_ERR(ts->reg);
+		dev_err(dev, "unable to get regulator: %d\n", err);
+		return err;
+	}
+
+	err = regulator_enable(ts->reg);
+	if (err) {
+		dev_err(dev, "unable to enable regulator: %d\n", err);
+		return err;
+	}
+
+	err = devm_add_action_or_reset(dev, ads7846_regulator_disable, ts->reg);
+	if (err)
+		return err;
+
+	irq_flags = pdata->irq_flags ? : IRQF_TRIGGER_FALLING;
+	irq_flags |= IRQF_ONESHOT;
+
+	err = devm_request_threaded_irq(dev, spi->irq,
+					ads7846_hard_irq, ads7846_irq,
+					irq_flags, dev->driver->name, ts);
+	if (err && err != -EPROBE_DEFER && !pdata->irq_flags) {
+		dev_info(dev,
+			"trying pin change workaround on irq %d\n", spi->irq);
+		irq_flags |= IRQF_TRIGGER_RISING;
+		err = devm_request_threaded_irq(dev, spi->irq,
+						ads7846_hard_irq, ads7846_irq,
+						irq_flags, dev->driver->name,
+						ts);
+	}
+
+	if (err) {
+		dev_dbg(dev, "irq %d busy?\n", spi->irq);
+		return err;
+	}
+
+	err = ads784x_hwmon_register(spi, ts);
+	if (err)
+		return err;
+
+	dev_info(dev, "touchscreen, irq %d\n", 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(dev, PWRDOWN);
+	else
+		(void) ads7846_read12_ser(dev, READ_12BIT_SER(vaux));
+
+	err = input_register_device(input_dev);
+	if (err)
+		return err;
+
+	device_init_wakeup(dev, pdata->wakeup);
+
+	/*
+	 * If device does not carry platform data we must have allocated it
+	 * when parsing DT data.
+	 */
+	if (!dev_get_platdata(dev))
+		devm_kfree(dev, (void *)pdata);
+
+	return 0;
+}
+
+static void ads7846_remove(struct spi_device *spi)
+{
+	struct ads7846 *ts = spi_get_drvdata(spi);
+
+	ads7846_stop(ts);
+}
+
+static struct spi_driver ads7846_driver = {
+	.driver = {
+		.name		= "ads7846",
+		.dev_groups	= ads784x_groups,
+		.pm		= pm_sleep_ptr(&ads7846_pm),
+		.of_match_table	= ads7846_dt_ids,
+	},
+	.probe		= ads7846_probe,
+	.remove		= ads7846_remove,
+	.id_table	= ads7846_spi_ids,
+};
+
+module_spi_driver(ads7846_driver);
+
+MODULE_DESCRIPTION("ADS7846 TouchScreen Driver");
+MODULE_LICENSE("GPL");