[PATCH 2/6] Add chip driver for WM9705 touchscreen

[Mark Brown <broonie@opensource.wolfsonmicro.com>]

Signed-off-by: Liam Girdwood <liam.girdwood@wolfsonmicro.com>
Signed-off-by: Graeme Gregory <gg@opensource.wolfsonmicro.com>
Signed-off-by: Mike Arthur <mike.arthur@wolfsonmicro.com>
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
Cc: Dmitry Baryshkov <dbaryshkov@gmail.com>
Cc: Stanley Cai <stanley.cai@intel.com>
Cc: Rodolfo Giometti <giometti@enneenne.com>
Cc: Russell King <rmk@arm.linux.org.uk>
Cc: Marc Kleine-Budde <mkl@pengutronix.de>
Cc: Ian Molton <spyro@f2s.com>
Cc: Vince Sanders <vince@kyllikki.org>
Cc: Andrew Zabolotny <zap@homelink.ru>
---
 drivers/input/touchscreen/wm9705.c |  352 ++++++++++++++++++++++++++++++++++++
 1 files changed, 352 insertions(+), 0 deletions(-)
 create mode 100644 drivers/input/touchscreen/wm9705.c

diff --git a/drivers/input/touchscreen/wm9705.c b/drivers/input/touchscreen/wm9705.c
new file mode 100644
index 0000000..f185104
--- /dev/null
+++ b/drivers/input/touchscreen/wm9705.c
@@ -0,0 +1,352 @@
+/*
+ * wm9705.c  --  Codec driver for Wolfson WM9705 AC97 Codec.
+ *
+ * Copyright 2003, 2004, 2005, 2006, 2007 Wolfson Microelectronics PLC.
+ * Author: Liam Girdwood
+ *         liam.girdwood@wolfsonmicro.com or linux@wolfsonmicro.com
+ * Parts Copyright : Ian Molton <spyro@f2s.com>
+ *                   Andrew Zabolotny <zap@homelink.ru>
+ *                   Russell King <rmk@arm.linux.org.uk>
+ *
+ *  This program is free software; you can redistribute  it and/or modify it
+ *  under  the terms of  the GNU General  Public License as published by the
+ *  Free Software Foundation;  either version 2 of the  License, or (at your
+ *  option) any later version.
+ *
+ */
+
+#include <linux/module.h>
+#include <linux/moduleparam.h>
+#include <linux/version.h>
+#include <linux/kernel.h>
+#include <linux/input.h>
+#include <linux/delay.h>
+#include <linux/bitops.h>
+#include <linux/wm97xx.h>
+
+#define TS_NAME			"wm97xx"
+#define WM9705_VERSION		"0.62"
+#define DEFAULT_PRESSURE	0xb0c0
+
+/*
+ * 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(pil, "Set current used for pressure measurement.");
+
+/*
+ * Set threshold for pressure measurement.
+ *
+ * Pen down pressure below threshold is ignored.
+ */
+static int pressure = DEFAULT_PRESSURE & 0xfff;
+module_param(pressure, int, 0);
+MODULE_PARM_DESC(pressure, "Set threshold for pressure measurement.");
+
+/*
+ * 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 = 4;
+module_param(delay, int, 0);
+MODULE_PARM_DESC(delay, "Set adc sample delay.");
+
+/*
+ * 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 = 8;
+module_param(pdd, int, 0);
+MODULE_PARM_DESC(pdd, "Set pen detect comparator threshold");
+
+/*
+ * 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(mask, "Set adc mask function.");
+
+/*
+ * ADC sample delay times in uS
+ */
+static const int delay_table[] = {
+	21,    /* 1 AC97 Link frames */
+	42,    /* 2                  */
+	84,    /* 4                  */
+	167,   /* 8                  */
+	333,   /* 16                 */
+	667,   /* 32                 */
+	1000,  /* 48                 */
+	1333,  /* 64                 */
+	2000,  /* 96                 */
+	2667,  /* 128                */
+	3333,  /* 160                */
+	4000,  /* 192                */
+	4667,  /* 224                */
+	5333,  /* 256                */
+	6000,  /* 288                */
+	0      /* No delay, switch matrix always on */
+};
+
+/*
+ * Delay after issuing a POLL command.
+ *
+ * The delay is 3 AC97 link frames + the touchpanel settling delay
+ */
+static inline void poll_delay(int d)
+{
+	udelay(3 * AC97_LINK_FRAME + delay_table[d]);
+}
+
+/*
+ * set up the physical settings of the WM9705
+ */
+static void wm9705_phy_init(struct wm97xx *wm)
+{
+	u16 dig1 = 0, dig2 = WM97XX_RPR;
+
+	/*
+	* mute VIDEO and AUX as they share X and Y touchscreen
+	* inputs on the WM9705
+	*/
+	wm97xx_reg_write(wm, AC97_AUX, 0x8000);
+	wm97xx_reg_write(wm, AC97_VIDEO, 0x8000);
+
+	/* touchpanel pressure current*/
+	if (pil == 2) {
+		dig2 |= WM9705_PIL;
+		dev_dbg(wm->dev,
+			"setting pressure measurement current to 400uA.");
+	} else if (pil)
+		dev_dbg(wm->dev,
+			"setting pressure measurement current to 200uA.");
+	if (!pil)
+		pressure = 0;
+
+	/* polling mode sample settling delay */
+	if (delay != 4) {
+		if (delay < 0 || delay > 15) {
+			dev_dbg(wm->dev, "supplied delay out of range.");
+			delay = 4;
+		}
+	}
+	dig1 &= 0xff0f;
+	dig1 |= WM97XX_DELAY(delay);
+	dev_dbg(wm->dev, "setting adc sample delay to %d u Secs.",
+		delay_table[delay]);
+
+	/* WM9705 pdd */
+	dig2 |= (pdd & 0x000f);
+	dev_dbg(wm->dev, "setting pdd to Vmid/%d", 1 - (pdd & 0x000f));
+
+	/* mask */
+	dig2 |= ((mask & 0x3) << 4);
+
+	wm97xx_reg_write(wm, AC97_WM97XX_DIGITISER1, dig1);
+	wm97xx_reg_write(wm, AC97_WM97XX_DIGITISER2, dig2);
+}
+
+static void wm9705_dig_enable(struct wm97xx *wm, int enable)
+{
+	if (enable) {
+		wm97xx_reg_write(wm, AC97_WM97XX_DIGITISER2,
+				 wm->dig[2] | WM97XX_PRP_DET_DIG);
+		wm97xx_reg_read(wm, AC97_WM97XX_DIGITISER_RD); /* dummy read */
+	} else
+		wm97xx_reg_write(wm, AC97_WM97XX_DIGITISER2,
+				 wm->dig[2] & ~WM97XX_PRP_DET_DIG);
+}
+
+static void wm9705_aux_prepare(struct wm97xx *wm)
+{
+	memcpy(wm->dig_save, wm->dig, sizeof(wm->dig));
+	wm97xx_reg_write(wm, AC97_WM97XX_DIGITISER1, 0);
+	wm97xx_reg_write(wm, AC97_WM97XX_DIGITISER2, WM97XX_PRP_DET_DIG);
+}
+
+static void wm9705_dig_restore(struct wm97xx *wm)
+{
+	wm97xx_reg_write(wm, AC97_WM97XX_DIGITISER1, wm->dig_save[1]);
+	wm97xx_reg_write(wm, AC97_WM97XX_DIGITISER2, wm->dig_save[2]);
+}
+
+static inline int is_pden(struct wm97xx *wm)
+{
+	return wm->dig[2] & WM9705_PDEN;
+}
+
+/*
+ * Read a sample from the WM9705 adc in polling mode.
+ */
+static int wm9705_poll_sample(struct wm97xx *wm, int adcsel, int *sample)
+{
+	int timeout = 5 * delay;
+
+	if (!wm->pen_probably_down) {
+		u16 data = wm97xx_reg_read(wm, AC97_WM97XX_DIGITISER_RD);
+		if (!(data & WM97XX_PEN_DOWN))
+			return RC_PENUP;
+		wm->pen_probably_down = 1;
+	}
+
+	/* set up digitiser */
+	if (adcsel & 0x8000)
+		adcsel = ((adcsel & 0x7fff) + 3) << 12;
+
+	if (wm->mach_ops && wm->mach_ops->pre_sample)
+		wm->mach_ops->pre_sample(adcsel);
+	wm97xx_reg_write(wm, AC97_WM97XX_DIGITISER1,
+			 adcsel | WM97XX_POLL | WM97XX_DELAY(delay));
+
+	/* wait 3 AC97 time slots + delay for conversion */
+	poll_delay(delay);
+
+	/* wait for POLL to go low */
+	while ((wm97xx_reg_read(wm, AC97_WM97XX_DIGITISER1) & WM97XX_POLL)
+	       && timeout) {
+		udelay(AC97_LINK_FRAME);
+		timeout--;
+	}
+
+	if (timeout <= 0) {
+		/* If PDEN is set, we can get a timeout when pen goes up */
+		if (is_pden(wm))
+			wm->pen_probably_down = 0;
+		else
+			dev_dbg(wm->dev, "adc sample timeout");
+		return RC_PENUP;
+	}
+
+	*sample = wm97xx_reg_read(wm, AC97_WM97XX_DIGITISER_RD);
+	if (wm->mach_ops && wm->mach_ops->post_sample)
+		wm->mach_ops->post_sample(adcsel);
+
+	/* check we have correct sample */
+	if ((*sample & WM97XX_ADCSEL_MASK) != adcsel) {
+		dev_dbg(wm->dev, "adc wrong sample, read %x got %x", adcsel,
+		*sample & WM97XX_ADCSEL_MASK);
+		return RC_PENUP;
+	}
+
+	if (!(*sample & WM97XX_PEN_DOWN)) {
+		wm->pen_probably_down = 0;
+		return RC_PENUP;
+	}
+
+	return RC_VALID;
+}
+
+/*
+ * Sample the WM9705 touchscreen in polling mode
+ */
+static int wm9705_poll_touch(struct wm97xx *wm, struct wm97xx_data *data)
+{
+	int rc;
+
+	rc = wm9705_poll_sample(wm, WM97XX_ADCSEL_X, &data->x);
+	if (rc != RC_VALID)
+		return rc;
+	rc = wm9705_poll_sample(wm, WM97XX_ADCSEL_Y, &data->y);
+	if (rc != RC_VALID)
+		return rc;
+	if (pil) {
+		rc = wm9705_poll_sample(wm, WM97XX_ADCSEL_PRES, &data->p);
+		if (rc != RC_VALID)
+			return rc;
+	} else
+		data->p = DEFAULT_PRESSURE;
+
+	return RC_VALID;
+}
+
+/*
+ * Enable WM9705 continuous mode, i.e. touch data is streamed across
+ * an AC97 slot
+ */
+static int wm9705_acc_enable(struct wm97xx *wm, int enable)
+{
+	u16 dig1, dig2;
+	int ret = 0;
+
+	dig1 = wm->dig[1];
+	dig2 = wm->dig[2];
+
+	if (enable) {
+		/* continous mode */
+		if (wm->mach_ops->acc_startup &&
+		    (ret = wm->mach_ops->acc_startup(wm)) < 0)
+			return ret;
+		dig1 &= ~(WM97XX_CM_RATE_MASK | WM97XX_ADCSEL_MASK |
+			  WM97XX_DELAY_MASK | WM97XX_SLT_MASK);
+		dig1 |= WM97XX_CTC | WM97XX_COO | WM97XX_SLEN |
+			WM97XX_DELAY(delay) |
+			WM97XX_SLT(wm->acc_slot) |
+			WM97XX_RATE(wm->acc_rate);
+		if (pil)
+			dig1 |= WM97XX_ADCSEL_PRES;
+		dig2 |= WM9705_PDEN;
+	} else {
+		dig1 &= ~(WM97XX_CTC | WM97XX_COO | WM97XX_SLEN);
+		dig2 &= ~WM9705_PDEN;
+		if (wm->mach_ops->acc_shutdown)
+			wm->mach_ops->acc_shutdown(wm);
+	}
+
+	wm97xx_reg_write(wm, AC97_WM97XX_DIGITISER1, dig1);
+	wm97xx_reg_write(wm, AC97_WM97XX_DIGITISER2, dig2);
+	return ret;
+}
+
+struct wm97xx_codec_drv wm9705_codec = {
+	.id = 	WM9705_ID2,
+	.name = "wm9705",
+	.poll_sample = wm9705_poll_sample,
+	.poll_touch = wm9705_poll_touch,
+	.acc_enable = wm9705_acc_enable,
+	.phy_init = wm9705_phy_init,
+	.dig_enable = wm9705_dig_enable,
+	.dig_restore = wm9705_dig_restore,
+	.aux_prepare = wm9705_aux_prepare,
+};
+EXPORT_SYMBOL_GPL(wm9705_codec);
+
+/* Module information */
+MODULE_AUTHOR("Liam Girdwood <liam.girdwood@wolfsonmicro.com>");
+MODULE_DESCRIPTION("WM9705 Touch Screen Driver");
+MODULE_LICENSE("GPL");
-- 
1.5.3.8