linux/drivers/input/touchscreen/wm9705.c

// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * wm9705.c  --  Codec driver for Wolfson WM9705 AC97 Codec.
 *
 * Copyright 2003, 2004, 2005, 2006, 2007 Wolfson Microelectronics PLC.
 * Author: Liam Girdwood <[email protected]>
 * Parts Copyright : Ian Molton <[email protected]>
 *                   Andrew Zabolotny <[email protected]>
 *                   Russell King <[email protected]>
 */

#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/kernel.h>
#include <linux/input.h>
#include <linux/delay.h>
#include <linux/bitops.h>
#include <linux/wm97xx.h>

#define TS_NAME …
#define WM9705_VERSION …
#define DEFAULT_PRESSURE …

/*
 * Module parameters
 */

/*
 * Set current used for pressure measurement.
 *
 * Set pil = 2 to use 400uA
 *     pil = 1 to use 200uA and
 *     pil = 0 to disable pressure measurement.
 *
 * This is used to increase the range of values returned by the adc
 * when measureing touchpanel pressure.
 */
static int pil;
module_param(pil, int, 0);
MODULE_PARM_DESC(…) …;

/*
 * Set threshold for pressure measurement.
 *
 * Pen down pressure below threshold is ignored.
 */
static int pressure = …;
module_param(pressure, int, 0);
MODULE_PARM_DESC(…) …;

/*
 * Set adc sample delay.
 *
 * For accurate touchpanel measurements, some settling time may be
 * required between the switch matrix applying a voltage across the
 * touchpanel plate and the ADC sampling the signal.
 *
 * This delay can be set by setting delay = n, where n is the array
 * position of the delay in the array delay_table below.
 * Long delays > 1ms are supported for completeness, but are not
 * recommended.
 */
static int delay = …;
module_param(delay, int, 0);
MODULE_PARM_DESC(…) …;

/*
 * Pen detect comparator threshold.
 *
 * 0 to Vmid in 15 steps, 0 = use zero power comparator with Vmid threshold
 * i.e. 1 =  Vmid/15 threshold
 *      15 =  Vmid/1 threshold
 *
 * Adjust this value if you are having problems with pen detect not
 * detecting any down events.
 */
static int pdd = …;
module_param(pdd, int, 0);
MODULE_PARM_DESC(…) …;

/*
 * Set adc mask function.
 *
 * Sources of glitch noise, such as signals driving an LCD display, may feed
 * through to the touch screen plates and affect measurement accuracy. In
 * order to minimise this, a signal may be applied to the MASK pin to delay or
 * synchronise the sampling.
 *
 * 0 = No delay or sync
 * 1 = High on pin stops conversions
 * 2 = Edge triggered, edge on pin delays conversion by delay param (above)
 * 3 = Edge triggered, edge on pin starts conversion after delay param
 */
static int mask;
module_param(mask, int, 0);
MODULE_PARM_DESC(…) …;

/*
 * ADC sample delay times in uS
 */
static const int delay_table[] = …;

/*
 * Delay after issuing a POLL command.
 *
 * The delay is 3 AC97 link frames + the touchpanel settling delay
 */
static inline void poll_delay(int d)
{ … }

/*
 * set up the physical settings of the WM9705
 */
static void wm9705_phy_init(struct wm97xx *wm)
{ … }

static void wm9705_dig_enable(struct wm97xx *wm, int enable)
{ … }

static void wm9705_aux_prepare(struct wm97xx *wm)
{ … }

static void wm9705_dig_restore(struct wm97xx *wm)
{ … }

static inline int is_pden(struct wm97xx *wm)
{ … }

/*
 * Read a sample from the WM9705 adc in polling mode.
 */
static int wm9705_poll_sample(struct wm97xx *wm, int adcsel, int *sample)
{ … }

/*
 * Sample the WM9705 touchscreen in polling mode
 */
static int wm9705_poll_touch(struct wm97xx *wm, struct wm97xx_data *data)
{ … }

/*
 * Enable WM9705 continuous mode, i.e. touch data is streamed across
 * an AC97 slot
 */
static int wm9705_acc_enable(struct wm97xx *wm, int enable)
{ … }

struct wm97xx_codec_drv wm9705_codec = …;
EXPORT_SYMBOL_GPL(…);

/* Module information */
MODULE_AUTHOR(…) …;
MODULE_DESCRIPTION(…) …;
MODULE_LICENSE(…) …;