1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3  * wm9705.c  --  Codec driver for Wolfson WM9705 AC97 Codec.
4  *
5  * Copyright 2003, 2004, 2005, 2006, 2007 Wolfson Microelectronics PLC.
6  * Author: Liam Girdwood <lrg@slimlogic.co.uk>
7  * Parts Copyright : Ian Molton <spyro@f2s.com>
8  *                   Andrew Zabolotny <zap@homelink.ru>
9  *                   Russell King <rmk@arm.linux.org.uk>
10  */
11 
12 #include <linux/module.h>
13 #include <linux/moduleparam.h>
14 #include <linux/kernel.h>
15 #include <linux/input.h>
16 #include <linux/delay.h>
17 #include <linux/bitops.h>
18 #include <linux/wm97xx.h>
19 
20 #define TS_NAME			"wm97xx"
21 #define WM9705_VERSION		"1.00"
22 #define DEFAULT_PRESSURE	0xb0c0
23 
24 /*
25  * Module parameters
26  */
27 
28 /*
29  * Set current used for pressure measurement.
30  *
31  * Set pil = 2 to use 400uA
32  *     pil = 1 to use 200uA and
33  *     pil = 0 to disable pressure measurement.
34  *
35  * This is used to increase the range of values returned by the adc
36  * when measureing touchpanel pressure.
37  */
38 static int pil;
39 module_param(pil, int, 0);
40 MODULE_PARM_DESC(pil, "Set current used for pressure measurement.");
41 
42 /*
43  * Set threshold for pressure measurement.
44  *
45  * Pen down pressure below threshold is ignored.
46  */
47 static int pressure = DEFAULT_PRESSURE & 0xfff;
48 module_param(pressure, int, 0);
49 MODULE_PARM_DESC(pressure, "Set threshold for pressure measurement.");
50 
51 /*
52  * Set adc sample delay.
53  *
54  * For accurate touchpanel measurements, some settling time may be
55  * required between the switch matrix applying a voltage across the
56  * touchpanel plate and the ADC sampling the signal.
57  *
58  * This delay can be set by setting delay = n, where n is the array
59  * position of the delay in the array delay_table below.
60  * Long delays > 1ms are supported for completeness, but are not
61  * recommended.
62  */
63 static int delay = 4;
64 module_param(delay, int, 0);
65 MODULE_PARM_DESC(delay, "Set adc sample delay.");
66 
67 /*
68  * Pen detect comparator threshold.
69  *
70  * 0 to Vmid in 15 steps, 0 = use zero power comparator with Vmid threshold
71  * i.e. 1 =  Vmid/15 threshold
72  *      15 =  Vmid/1 threshold
73  *
74  * Adjust this value if you are having problems with pen detect not
75  * detecting any down events.
76  */
77 static int pdd = 8;
78 module_param(pdd, int, 0);
79 MODULE_PARM_DESC(pdd, "Set pen detect comparator threshold");
80 
81 /*
82  * Set adc mask function.
83  *
84  * Sources of glitch noise, such as signals driving an LCD display, may feed
85  * through to the touch screen plates and affect measurement accuracy. In
86  * order to minimise this, a signal may be applied to the MASK pin to delay or
87  * synchronise the sampling.
88  *
89  * 0 = No delay or sync
90  * 1 = High on pin stops conversions
91  * 2 = Edge triggered, edge on pin delays conversion by delay param (above)
92  * 3 = Edge triggered, edge on pin starts conversion after delay param
93  */
94 static int mask;
95 module_param(mask, int, 0);
96 MODULE_PARM_DESC(mask, "Set adc mask function.");
97 
98 /*
99  * ADC sample delay times in uS
100  */
101 static const int delay_table[] = {
102 	21,    /* 1 AC97 Link frames */
103 	42,    /* 2                  */
104 	84,    /* 4                  */
105 	167,   /* 8                  */
106 	333,   /* 16                 */
107 	667,   /* 32                 */
108 	1000,  /* 48                 */
109 	1333,  /* 64                 */
110 	2000,  /* 96                 */
111 	2667,  /* 128                */
112 	3333,  /* 160                */
113 	4000,  /* 192                */
114 	4667,  /* 224                */
115 	5333,  /* 256                */
116 	6000,  /* 288                */
117 	0      /* No delay, switch matrix always on */
118 };
119 
120 /*
121  * Delay after issuing a POLL command.
122  *
123  * The delay is 3 AC97 link frames + the touchpanel settling delay
124  */
125 static inline void poll_delay(int d)
126 {
127 	udelay(3 * AC97_LINK_FRAME + delay_table[d]);
128 }
129 
130 /*
131  * set up the physical settings of the WM9705
132  */
133 static void wm9705_phy_init(struct wm97xx *wm)
134 {
135 	u16 dig1 = 0, dig2 = WM97XX_RPR;
136 
137 	/*
138 	* mute VIDEO and AUX as they share X and Y touchscreen
139 	* inputs on the WM9705
140 	*/
141 	wm97xx_reg_write(wm, AC97_AUX, 0x8000);
142 	wm97xx_reg_write(wm, AC97_VIDEO, 0x8000);
143 
144 	/* touchpanel pressure current*/
145 	if (pil == 2) {
146 		dig2 |= WM9705_PIL;
147 		dev_dbg(wm->dev,
148 			"setting pressure measurement current to 400uA.");
149 	} else if (pil)
150 		dev_dbg(wm->dev,
151 			"setting pressure measurement current to 200uA.");
152 	if (!pil)
153 		pressure = 0;
154 
155 	/* polling mode sample settling delay */
156 	if (delay != 4) {
157 		if (delay < 0 || delay > 15) {
158 			dev_dbg(wm->dev, "supplied delay out of range.");
159 			delay = 4;
160 		}
161 	}
162 	dig1 &= 0xff0f;
163 	dig1 |= WM97XX_DELAY(delay);
164 	dev_dbg(wm->dev, "setting adc sample delay to %d u Secs.",
165 		delay_table[delay]);
166 
167 	/* WM9705 pdd */
168 	dig2 |= (pdd & 0x000f);
169 	dev_dbg(wm->dev, "setting pdd to Vmid/%d", 1 - (pdd & 0x000f));
170 
171 	/* mask */
172 	dig2 |= ((mask & 0x3) << 4);
173 
174 	wm97xx_reg_write(wm, AC97_WM97XX_DIGITISER1, dig1);
175 	wm97xx_reg_write(wm, AC97_WM97XX_DIGITISER2, dig2);
176 }
177 
178 static void wm9705_dig_enable(struct wm97xx *wm, int enable)
179 {
180 	if (enable) {
181 		wm97xx_reg_write(wm, AC97_WM97XX_DIGITISER2,
182 				 wm->dig[2] | WM97XX_PRP_DET_DIG);
183 		wm97xx_reg_read(wm, AC97_WM97XX_DIGITISER_RD); /* dummy read */
184 	} else
185 		wm97xx_reg_write(wm, AC97_WM97XX_DIGITISER2,
186 				 wm->dig[2] & ~WM97XX_PRP_DET_DIG);
187 }
188 
189 static void wm9705_aux_prepare(struct wm97xx *wm)
190 {
191 	memcpy(wm->dig_save, wm->dig, sizeof(wm->dig));
192 	wm97xx_reg_write(wm, AC97_WM97XX_DIGITISER1, 0);
193 	wm97xx_reg_write(wm, AC97_WM97XX_DIGITISER2, WM97XX_PRP_DET_DIG);
194 }
195 
196 static void wm9705_dig_restore(struct wm97xx *wm)
197 {
198 	wm97xx_reg_write(wm, AC97_WM97XX_DIGITISER1, wm->dig_save[1]);
199 	wm97xx_reg_write(wm, AC97_WM97XX_DIGITISER2, wm->dig_save[2]);
200 }
201 
202 static inline int is_pden(struct wm97xx *wm)
203 {
204 	return wm->dig[2] & WM9705_PDEN;
205 }
206 
207 /*
208  * Read a sample from the WM9705 adc in polling mode.
209  */
210 static int wm9705_poll_sample(struct wm97xx *wm, int adcsel, int *sample)
211 {
212 	int timeout = 5 * delay;
213 	bool wants_pen = adcsel & WM97XX_PEN_DOWN;
214 
215 	if (wants_pen && !wm->pen_probably_down) {
216 		u16 data = wm97xx_reg_read(wm, AC97_WM97XX_DIGITISER_RD);
217 		if (!(data & WM97XX_PEN_DOWN))
218 			return RC_PENUP;
219 		wm->pen_probably_down = 1;
220 	}
221 
222 	/* set up digitiser */
223 	if (wm->mach_ops && wm->mach_ops->pre_sample)
224 		wm->mach_ops->pre_sample(adcsel);
225 	wm97xx_reg_write(wm, AC97_WM97XX_DIGITISER1, (adcsel & WM97XX_ADCSEL_MASK)
226 				| WM97XX_POLL | WM97XX_DELAY(delay));
227 
228 	/* wait 3 AC97 time slots + delay for conversion */
229 	poll_delay(delay);
230 
231 	/* wait for POLL to go low */
232 	while ((wm97xx_reg_read(wm, AC97_WM97XX_DIGITISER1) & WM97XX_POLL)
233 	       && timeout) {
234 		udelay(AC97_LINK_FRAME);
235 		timeout--;
236 	}
237 
238 	if (timeout == 0) {
239 		/* If PDEN is set, we can get a timeout when pen goes up */
240 		if (is_pden(wm))
241 			wm->pen_probably_down = 0;
242 		else
243 			dev_dbg(wm->dev, "adc sample timeout");
244 		return RC_PENUP;
245 	}
246 
247 	*sample = wm97xx_reg_read(wm, AC97_WM97XX_DIGITISER_RD);
248 	if (wm->mach_ops && wm->mach_ops->post_sample)
249 		wm->mach_ops->post_sample(adcsel);
250 
251 	/* check we have correct sample */
252 	if ((*sample ^ adcsel) & WM97XX_ADCSEL_MASK) {
253 		dev_dbg(wm->dev, "adc wrong sample, wanted %x got %x",
254 			adcsel & WM97XX_ADCSEL_MASK,
255 			*sample & WM97XX_ADCSEL_MASK);
256 		return RC_PENUP;
257 	}
258 
259 	if (wants_pen && !(*sample & WM97XX_PEN_DOWN)) {
260 		wm->pen_probably_down = 0;
261 		return RC_PENUP;
262 	}
263 
264 	return RC_VALID;
265 }
266 
267 /*
268  * Sample the WM9705 touchscreen in polling mode
269  */
270 static int wm9705_poll_touch(struct wm97xx *wm, struct wm97xx_data *data)
271 {
272 	int rc;
273 
274 	rc = wm9705_poll_sample(wm, WM97XX_ADCSEL_X | WM97XX_PEN_DOWN, &data->x);
275 	if (rc != RC_VALID)
276 		return rc;
277 	rc = wm9705_poll_sample(wm, WM97XX_ADCSEL_Y | WM97XX_PEN_DOWN, &data->y);
278 	if (rc != RC_VALID)
279 		return rc;
280 	if (pil) {
281 		rc = wm9705_poll_sample(wm, WM97XX_ADCSEL_PRES | WM97XX_PEN_DOWN, &data->p);
282 		if (rc != RC_VALID)
283 			return rc;
284 	} else
285 		data->p = DEFAULT_PRESSURE;
286 
287 	return RC_VALID;
288 }
289 
290 /*
291  * Enable WM9705 continuous mode, i.e. touch data is streamed across
292  * an AC97 slot
293  */
294 static int wm9705_acc_enable(struct wm97xx *wm, int enable)
295 {
296 	u16 dig1, dig2;
297 	int ret = 0;
298 
299 	dig1 = wm->dig[1];
300 	dig2 = wm->dig[2];
301 
302 	if (enable) {
303 		/* continuous mode */
304 		if (wm->mach_ops->acc_startup &&
305 		    (ret = wm->mach_ops->acc_startup(wm)) < 0)
306 			return ret;
307 		dig1 &= ~(WM97XX_CM_RATE_MASK | WM97XX_ADCSEL_MASK |
308 			  WM97XX_DELAY_MASK | WM97XX_SLT_MASK);
309 		dig1 |= WM97XX_CTC | WM97XX_COO | WM97XX_SLEN |
310 			WM97XX_DELAY(delay) |
311 			WM97XX_SLT(wm->acc_slot) |
312 			WM97XX_RATE(wm->acc_rate);
313 		if (pil)
314 			dig1 |= WM97XX_ADCSEL_PRES;
315 		dig2 |= WM9705_PDEN;
316 	} else {
317 		dig1 &= ~(WM97XX_CTC | WM97XX_COO | WM97XX_SLEN);
318 		dig2 &= ~WM9705_PDEN;
319 		if (wm->mach_ops->acc_shutdown)
320 			wm->mach_ops->acc_shutdown(wm);
321 	}
322 
323 	wm97xx_reg_write(wm, AC97_WM97XX_DIGITISER1, dig1);
324 	wm97xx_reg_write(wm, AC97_WM97XX_DIGITISER2, dig2);
325 
326 	return ret;
327 }
328 
329 struct wm97xx_codec_drv wm9705_codec = {
330 	.id = WM9705_ID2,
331 	.name = "wm9705",
332 	.poll_sample = wm9705_poll_sample,
333 	.poll_touch = wm9705_poll_touch,
334 	.acc_enable = wm9705_acc_enable,
335 	.phy_init = wm9705_phy_init,
336 	.dig_enable = wm9705_dig_enable,
337 	.dig_restore = wm9705_dig_restore,
338 	.aux_prepare = wm9705_aux_prepare,
339 };
340 EXPORT_SYMBOL_GPL(wm9705_codec);
341 
342 /* Module information */
343 MODULE_AUTHOR("Liam Girdwood <lrg@slimlogic.co.uk>");
344 MODULE_DESCRIPTION("WM9705 Touch Screen Driver");
345 MODULE_LICENSE("GPL");
346