path: root/drivers/input/touchscreen/ads7846.c

/*
 * 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/hwmon.h>
#include <linux/init.h>
#include <linux/err.h>
#include <linux/delay.h>
#include <linux/input.h>
#include <linux/interrupt.h>
#include <linux/slab.h>
#include <linux/gpio.h>
#include <linux/spi/spi.h>
#include <linux/spi/ads7846.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).
 * TSC2046 is just newer ads7846 silicon.
 * Support for ads7843 tested on Atmel at91sam926x-EK.
 * Support for ads7845 has only been stubbed in.
 *
 * 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 * 1000000)	/* ns delay before the first sample */
#define TS_POLL_PERIOD	(5 * 1000000)	/* ns 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 byteorder 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;
	int	ignore;
};

/*
 * 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;
};

struct ads7846 {
	struct input_dev	*input;
	char			phys[32];

	struct spi_device	*spi;

#if defined(CONFIG_HWMON) || defined(CONFIG_HWMON_MODULE)
	struct attribute_group	*attr_group;
	struct device		*hwmon;
#endif

	u16			model;
	u16			vref_mv;
	u16			vref_delay_usecs;
	u16			x_plate_ohms;
	u16			pressure_max;

	struct ads7846_packet	*packet;

	struct spi_transfer	xfer[18];
	struct spi_message	msg[5];
	struct spi_message	*last_msg;
	int			msg_idx;
	int			read_cnt;
	int			read_rep;
	int			last_read;

	u16			debounce_max;
	u16			debounce_tol;
	u16			debounce_rep;

	u16			penirq_recheck_delay_usecs;

	spinlock_t		lock;
	struct hrtimer		timer;
	unsigned		pendown:1;	/* P: lock */
	unsigned		pending:1;	/* P: lock */
// FIXME remove "irq_disabled"
	unsigned		irq_disabled:1;	/* P: lock */
	unsigned		disabled:1;
	unsigned		is_suspended:1;

	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;
};

/* 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)
#defin