1 /***************************************************************************
2  *   Copyright (C) 2010-2012 Hans de Goede <hdegoede@redhat.com>           *
3  *                                                                         *
4  *   This program is free software; you can redistribute it and/or modify  *
5  *   it under the terms of the GNU General Public License as published by  *
6  *   the Free Software Foundation; either version 2 of the License, or     *
7  *   (at your option) any later version.                                   *
8  *                                                                         *
9  *   This program is distributed in the hope that it will be useful,       *
10  *   but WITHOUT ANY WARRANTY; without even the implied warranty of        *
11  *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the         *
12  *   GNU General Public License for more details.                          *
13  *                                                                         *
14  *   You should have received a copy of the GNU General Public License     *
15  *   along with this program; if not, write to the                         *
16  *   Free Software Foundation, Inc.,                                       *
17  *   59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.             *
18  ***************************************************************************/
19 
20 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
21 
22 #include <linux/module.h>
23 #include <linux/init.h>
24 #include <linux/platform_device.h>
25 #include <linux/err.h>
26 #include <linux/io.h>
27 #include <linux/acpi.h>
28 #include <linux/delay.h>
29 #include <linux/fs.h>
30 #include <linux/watchdog.h>
31 #include <linux/miscdevice.h>
32 #include <linux/uaccess.h>
33 #include <linux/kref.h>
34 #include <linux/slab.h>
35 #include "sch56xx-common.h"
36 
37 /* Insmod parameters */
38 static int nowayout = WATCHDOG_NOWAYOUT;
39 module_param(nowayout, int, 0);
40 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="
41 	__MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
42 
43 #define SIO_SCH56XX_LD_EM	0x0C	/* Embedded uController Logical Dev */
44 #define SIO_UNLOCK_KEY		0x55	/* Key to enable Super-I/O */
45 #define SIO_LOCK_KEY		0xAA	/* Key to disable Super-I/O */
46 
47 #define SIO_REG_LDSEL		0x07	/* Logical device select */
48 #define SIO_REG_DEVID		0x20	/* Device ID */
49 #define SIO_REG_ENABLE		0x30	/* Logical device enable */
50 #define SIO_REG_ADDR		0x66	/* Logical device address (2 bytes) */
51 
52 #define SIO_SCH5627_ID		0xC6	/* Chipset ID */
53 #define SIO_SCH5636_ID		0xC7	/* Chipset ID */
54 
55 #define REGION_LENGTH		10
56 
57 #define SCH56XX_CMD_READ	0x02
58 #define SCH56XX_CMD_WRITE	0x03
59 
60 /* Watchdog registers */
61 #define SCH56XX_REG_WDOG_PRESET		0x58B
62 #define SCH56XX_REG_WDOG_CONTROL	0x58C
63 #define SCH56XX_WDOG_TIME_BASE_SEC	0x01
64 #define SCH56XX_REG_WDOG_OUTPUT_ENABLE	0x58E
65 #define SCH56XX_WDOG_OUTPUT_ENABLE	0x02
66 
67 struct sch56xx_watchdog_data {
68 	u16 addr;
69 	struct mutex *io_lock;
70 	struct kref kref;
71 	struct watchdog_info wdinfo;
72 	struct watchdog_device wddev;
73 	u8 watchdog_preset;
74 	u8 watchdog_control;
75 	u8 watchdog_output_enable;
76 };
77 
78 static struct platform_device *sch56xx_pdev;
79 
80 /* Super I/O functions */
81 static inline int superio_inb(int base, int reg)
82 {
83 	outb(reg, base);
84 	return inb(base + 1);
85 }
86 
87 static inline int superio_enter(int base)
88 {
89 	/* Don't step on other drivers' I/O space by accident */
90 	if (!request_muxed_region(base, 2, "sch56xx")) {
91 		pr_err("I/O address 0x%04x already in use\n", base);
92 		return -EBUSY;
93 	}
94 
95 	outb(SIO_UNLOCK_KEY, base);
96 
97 	return 0;
98 }
99 
100 static inline void superio_select(int base, int ld)
101 {
102 	outb(SIO_REG_LDSEL, base);
103 	outb(ld, base + 1);
104 }
105 
106 static inline void superio_exit(int base)
107 {
108 	outb(SIO_LOCK_KEY, base);
109 	release_region(base, 2);
110 }
111 
112 static int sch56xx_send_cmd(u16 addr, u8 cmd, u16 reg, u8 v)
113 {
114 	u8 val;
115 	int i;
116 	/*
117 	 * According to SMSC for the commands we use the maximum time for
118 	 * the EM to respond is 15 ms, but testing shows in practice it
119 	 * responds within 15-32 reads, so we first busy poll, and if
120 	 * that fails sleep a bit and try again until we are way past
121 	 * the 15 ms maximum response time.
122 	 */
123 	const int max_busy_polls = 64;
124 	const int max_lazy_polls = 32;
125 
126 	/* (Optional) Write-Clear the EC to Host Mailbox Register */
127 	val = inb(addr + 1);
128 	outb(val, addr + 1);
129 
130 	/* Set Mailbox Address Pointer to first location in Region 1 */
131 	outb(0x00, addr + 2);
132 	outb(0x80, addr + 3);
133 
134 	/* Write Request Packet Header */
135 	outb(cmd, addr + 4); /* VREG Access Type read:0x02 write:0x03 */
136 	outb(0x01, addr + 5); /* # of Entries: 1 Byte (8-bit) */
137 	outb(0x04, addr + 2); /* Mailbox AP to first data entry loc. */
138 
139 	/* Write Value field */
140 	if (cmd == SCH56XX_CMD_WRITE)
141 		outb(v, addr + 4);
142 
143 	/* Write Address field */
144 	outb(reg & 0xff, addr + 6);
145 	outb(reg >> 8, addr + 7);
146 
147 	/* Execute the Random Access Command */
148 	outb(0x01, addr); /* Write 01h to the Host-to-EC register */
149 
150 	/* EM Interface Polling "Algorithm" */
151 	for (i = 0; i < max_busy_polls + max_lazy_polls; i++) {
152 		if (i >= max_busy_polls)
153 			msleep(1);
154 		/* Read Interrupt source Register */
155 		val = inb(addr + 8);
156 		/* Write Clear the interrupt source bits */
157 		if (val)
158 			outb(val, addr + 8);
159 		/* Command Completed ? */
160 		if (val & 0x01)
161 			break;
162 	}
163 	if (i == max_busy_polls + max_lazy_polls) {
164 		pr_err("Max retries exceeded reading virtual "
165 		       "register 0x%04hx (%d)\n", reg, 1);
166 		return -EIO;
167 	}
168 
169 	/*
170 	 * According to SMSC we may need to retry this, but sofar I've always
171 	 * seen this succeed in 1 try.
172 	 */
173 	for (i = 0; i < max_busy_polls; i++) {
174 		/* Read EC-to-Host Register */
175 		val = inb(addr + 1);
176 		/* Command Completed ? */
177 		if (val == 0x01)
178 			break;
179 
180 		if (i == 0)
181 			pr_warn("EC reports: 0x%02x reading virtual register "
182 				"0x%04hx\n", (unsigned int)val, reg);
183 	}
184 	if (i == max_busy_polls) {
185 		pr_err("Max retries exceeded reading virtual "
186 		       "register 0x%04hx (%d)\n", reg, 2);
187 		return -EIO;
188 	}
189 
190 	/*
191 	 * According to the SMSC app note we should now do:
192 	 *
193 	 * Set Mailbox Address Pointer to first location in Region 1 *
194 	 * outb(0x00, addr + 2);
195 	 * outb(0x80, addr + 3);
196 	 *
197 	 * But if we do that things don't work, so let's not.
198 	 */
199 
200 	/* Read Value field */
201 	if (cmd == SCH56XX_CMD_READ)
202 		return inb(addr + 4);
203 
204 	return 0;
205 }
206 
207 int sch56xx_read_virtual_reg(u16 addr, u16 reg)
208 {
209 	return sch56xx_send_cmd(addr, SCH56XX_CMD_READ, reg, 0);
210 }
211 EXPORT_SYMBOL(sch56xx_read_virtual_reg);
212 
213 int sch56xx_write_virtual_reg(u16 addr, u16 reg, u8 val)
214 {
215 	return sch56xx_send_cmd(addr, SCH56XX_CMD_WRITE, reg, val);
216 }
217 EXPORT_SYMBOL(sch56xx_write_virtual_reg);
218 
219 int sch56xx_read_virtual_reg16(u16 addr, u16 reg)
220 {
221 	int lsb, msb;
222 
223 	/* Read LSB first, this will cause the matching MSB to be latched */
224 	lsb = sch56xx_read_virtual_reg(addr, reg);
225 	if (lsb < 0)
226 		return lsb;
227 
228 	msb = sch56xx_read_virtual_reg(addr, reg + 1);
229 	if (msb < 0)
230 		return msb;
231 
232 	return lsb | (msb << 8);
233 }
234 EXPORT_SYMBOL(sch56xx_read_virtual_reg16);
235 
236 int sch56xx_read_virtual_reg12(u16 addr, u16 msb_reg, u16 lsn_reg,
237 			       int high_nibble)
238 {
239 	int msb, lsn;
240 
241 	/* Read MSB first, this will cause the matching LSN to be latched */
242 	msb = sch56xx_read_virtual_reg(addr, msb_reg);
243 	if (msb < 0)
244 		return msb;
245 
246 	lsn = sch56xx_read_virtual_reg(addr, lsn_reg);
247 	if (lsn < 0)
248 		return lsn;
249 
250 	if (high_nibble)
251 		return (msb << 4) | (lsn >> 4);
252 	else
253 		return (msb << 4) | (lsn & 0x0f);
254 }
255 EXPORT_SYMBOL(sch56xx_read_virtual_reg12);
256 
257 /*
258  * Watchdog routines
259  */
260 
261 /* Release our data struct when we're unregistered *and*
262    all references to our watchdog device are released */
263 static void watchdog_release_resources(struct kref *r)
264 {
265 	struct sch56xx_watchdog_data *data =
266 		container_of(r, struct sch56xx_watchdog_data, kref);
267 	kfree(data);
268 }
269 
270 static int watchdog_set_timeout(struct watchdog_device *wddev,
271 				unsigned int timeout)
272 {
273 	struct sch56xx_watchdog_data *data = watchdog_get_drvdata(wddev);
274 	unsigned int resolution;
275 	u8 control;
276 	int ret;
277 
278 	/* 1 second or 60 second resolution? */
279 	if (timeout <= 255)
280 		resolution = 1;
281 	else
282 		resolution = 60;
283 
284 	if (timeout < resolution || timeout > (resolution * 255))
285 		return -EINVAL;
286 
287 	if (resolution == 1)
288 		control = data->watchdog_control | SCH56XX_WDOG_TIME_BASE_SEC;
289 	else
290 		control = data->watchdog_control & ~SCH56XX_WDOG_TIME_BASE_SEC;
291 
292 	if (data->watchdog_control != control) {
293 		mutex_lock(data->io_lock);
294 		ret = sch56xx_write_virtual_reg(data->addr,
295 						SCH56XX_REG_WDOG_CONTROL,
296 						control);
297 		mutex_unlock(data->io_lock);
298 		if (ret)
299 			return ret;
300 
301 		data->watchdog_control = control;
302 	}
303 
304 	/*
305 	 * Remember new timeout value, but do not write as that (re)starts
306 	 * the watchdog countdown.
307 	 */
308 	data->watchdog_preset = DIV_ROUND_UP(timeout, resolution);
309 	wddev->timeout = data->watchdog_preset * resolution;
310 
311 	return 0;
312 }
313 
314 static int watchdog_start(struct watchdog_device *wddev)
315 {
316 	struct sch56xx_watchdog_data *data = watchdog_get_drvdata(wddev);
317 	int ret;
318 	u8 val;
319 
320 	/*
321 	 * The sch56xx's watchdog cannot really be started / stopped
322 	 * it is always running, but we can avoid the timer expiring
323 	 * from causing a system reset by clearing the output enable bit.
324 	 *
325 	 * The sch56xx's watchdog will set the watchdog event bit, bit 0
326 	 * of the second interrupt source register (at base-address + 9),
327 	 * when the timer expires.
328 	 *
329 	 * This will only cause a system reset if the 0-1 flank happens when
330 	 * output enable is true. Setting output enable after the flank will
331 	 * not cause a reset, nor will the timer expiring a second time.
332 	 * This means we must clear the watchdog event bit in case it is set.
333 	 *
334 	 * The timer may still be running (after a recent watchdog_stop) and
335 	 * mere milliseconds away from expiring, so the timer must be reset
336 	 * first!
337 	 */
338 
339 	mutex_lock(data->io_lock);
340 
341 	/* 1. Reset the watchdog countdown counter */
342 	ret = sch56xx_write_virtual_reg(data->addr, SCH56XX_REG_WDOG_PRESET,
343 					data->watchdog_preset);
344 	if (ret)
345 		goto leave;
346 
347 	/* 2. Enable output */
348 	val = data->watchdog_output_enable | SCH56XX_WDOG_OUTPUT_ENABLE;
349 	ret = sch56xx_write_virtual_reg(data->addr,
350 					SCH56XX_REG_WDOG_OUTPUT_ENABLE, val);
351 	if (ret)
352 		goto leave;
353 
354 	data->watchdog_output_enable = val;
355 
356 	/* 3. Clear the watchdog event bit if set */
357 	val = inb(data->addr + 9);
358 	if (val & 0x01)
359 		outb(0x01, data->addr + 9);
360 
361 leave:
362 	mutex_unlock(data->io_lock);
363 	return ret;
364 }
365 
366 static int watchdog_trigger(struct watchdog_device *wddev)
367 {
368 	struct sch56xx_watchdog_data *data = watchdog_get_drvdata(wddev);
369 	int ret;
370 
371 	/* Reset the watchdog countdown counter */
372 	mutex_lock(data->io_lock);
373 	ret = sch56xx_write_virtual_reg(data->addr, SCH56XX_REG_WDOG_PRESET,
374 					data->watchdog_preset);
375 	mutex_unlock(data->io_lock);
376 
377 	return ret;
378 }
379 
380 static int watchdog_stop(struct watchdog_device *wddev)
381 {
382 	struct sch56xx_watchdog_data *data = watchdog_get_drvdata(wddev);
383 	int ret = 0;
384 	u8 val;
385 
386 	val = data->watchdog_output_enable & ~SCH56XX_WDOG_OUTPUT_ENABLE;
387 	mutex_lock(data->io_lock);
388 	ret = sch56xx_write_virtual_reg(data->addr,
389 					SCH56XX_REG_WDOG_OUTPUT_ENABLE, val);
390 	mutex_unlock(data->io_lock);
391 	if (ret)
392 		return ret;
393 
394 	data->watchdog_output_enable = val;
395 	return 0;
396 }
397 
398 static void watchdog_ref(struct watchdog_device *wddev)
399 {
400 	struct sch56xx_watchdog_data *data = watchdog_get_drvdata(wddev);
401 
402 	kref_get(&data->kref);
403 }
404 
405 static void watchdog_unref(struct watchdog_device *wddev)
406 {
407 	struct sch56xx_watchdog_data *data = watchdog_get_drvdata(wddev);
408 
409 	kref_put(&data->kref, watchdog_release_resources);
410 }
411 
412 static const struct watchdog_ops watchdog_ops = {
413 	.owner		= THIS_MODULE,
414 	.start		= watchdog_start,
415 	.stop		= watchdog_stop,
416 	.ping		= watchdog_trigger,
417 	.set_timeout	= watchdog_set_timeout,
418 	.ref		= watchdog_ref,
419 	.unref		= watchdog_unref,
420 };
421 
422 struct sch56xx_watchdog_data *sch56xx_watchdog_register(struct device *parent,
423 	u16 addr, u32 revision, struct mutex *io_lock, int check_enabled)
424 {
425 	struct sch56xx_watchdog_data *data;
426 	int err, control, output_enable;
427 
428 	/* Cache the watchdog registers */
429 	mutex_lock(io_lock);
430 	control =
431 		sch56xx_read_virtual_reg(addr, SCH56XX_REG_WDOG_CONTROL);
432 	output_enable =
433 		sch56xx_read_virtual_reg(addr, SCH56XX_REG_WDOG_OUTPUT_ENABLE);
434 	mutex_unlock(io_lock);
435 
436 	if (control < 0)
437 		return NULL;
438 	if (output_enable < 0)
439 		return NULL;
440 	if (check_enabled && !(output_enable & SCH56XX_WDOG_OUTPUT_ENABLE)) {
441 		pr_warn("Watchdog not enabled by BIOS, not registering\n");
442 		return NULL;
443 	}
444 
445 	data = kzalloc(sizeof(struct sch56xx_watchdog_data), GFP_KERNEL);
446 	if (!data)
447 		return NULL;
448 
449 	data->addr = addr;
450 	data->io_lock = io_lock;
451 	kref_init(&data->kref);
452 
453 	strlcpy(data->wdinfo.identity, "sch56xx watchdog",
454 		sizeof(data->wdinfo.identity));
455 	data->wdinfo.firmware_version = revision;
456 	data->wdinfo.options = WDIOF_KEEPALIVEPING | WDIOF_SETTIMEOUT;
457 	if (!nowayout)
458 		data->wdinfo.options |= WDIOF_MAGICCLOSE;
459 
460 	data->wddev.info = &data->wdinfo;
461 	data->wddev.ops = &watchdog_ops;
462 	data->wddev.parent = parent;
463 	data->wddev.timeout = 60;
464 	data->wddev.min_timeout = 1;
465 	data->wddev.max_timeout = 255 * 60;
466 	if (nowayout)
467 		set_bit(WDOG_NO_WAY_OUT, &data->wddev.status);
468 	if (output_enable & SCH56XX_WDOG_OUTPUT_ENABLE)
469 		set_bit(WDOG_ACTIVE, &data->wddev.status);
470 
471 	/* Since the watchdog uses a downcounter there is no register to read
472 	   the BIOS set timeout from (if any was set at all) ->
473 	   Choose a preset which will give us a 1 minute timeout */
474 	if (control & SCH56XX_WDOG_TIME_BASE_SEC)
475 		data->watchdog_preset = 60; /* seconds */
476 	else
477 		data->watchdog_preset = 1; /* minute */
478 
479 	data->watchdog_control = control;
480 	data->watchdog_output_enable = output_enable;
481 
482 	watchdog_set_drvdata(&data->wddev, data);
483 	err = watchdog_register_device(&data->wddev);
484 	if (err) {
485 		pr_err("Registering watchdog chardev: %d\n", err);
486 		kfree(data);
487 		return NULL;
488 	}
489 
490 	return data;
491 }
492 EXPORT_SYMBOL(sch56xx_watchdog_register);
493 
494 void sch56xx_watchdog_unregister(struct sch56xx_watchdog_data *data)
495 {
496 	watchdog_unregister_device(&data->wddev);
497 	kref_put(&data->kref, watchdog_release_resources);
498 	/* Don't touch data after this it may have been free-ed! */
499 }
500 EXPORT_SYMBOL(sch56xx_watchdog_unregister);
501 
502 /*
503  * platform dev find, add and remove functions
504  */
505 
506 static int __init sch56xx_find(int sioaddr, unsigned short *address,
507 			       const char **name)
508 {
509 	u8 devid;
510 	int err;
511 
512 	err = superio_enter(sioaddr);
513 	if (err)
514 		return err;
515 
516 	devid = superio_inb(sioaddr, SIO_REG_DEVID);
517 	switch (devid) {
518 	case SIO_SCH5627_ID:
519 		*name = "sch5627";
520 		break;
521 	case SIO_SCH5636_ID:
522 		*name = "sch5636";
523 		break;
524 	default:
525 		pr_debug("Unsupported device id: 0x%02x\n",
526 			 (unsigned int)devid);
527 		err = -ENODEV;
528 		goto exit;
529 	}
530 
531 	superio_select(sioaddr, SIO_SCH56XX_LD_EM);
532 
533 	if (!(superio_inb(sioaddr, SIO_REG_ENABLE) & 0x01)) {
534 		pr_warn("Device not activated\n");
535 		err = -ENODEV;
536 		goto exit;
537 	}
538 
539 	/*
540 	 * Warning the order of the low / high byte is the other way around
541 	 * as on most other superio devices!!
542 	 */
543 	*address = superio_inb(sioaddr, SIO_REG_ADDR) |
544 		   superio_inb(sioaddr, SIO_REG_ADDR + 1) << 8;
545 	if (*address == 0) {
546 		pr_warn("Base address not set\n");
547 		err = -ENODEV;
548 		goto exit;
549 	}
550 
551 exit:
552 	superio_exit(sioaddr);
553 	return err;
554 }
555 
556 static int __init sch56xx_device_add(unsigned short address, const char *name)
557 {
558 	struct resource res = {
559 		.start	= address,
560 		.end	= address + REGION_LENGTH - 1,
561 		.flags	= IORESOURCE_IO,
562 	};
563 	int err;
564 
565 	sch56xx_pdev = platform_device_alloc(name, address);
566 	if (!sch56xx_pdev)
567 		return -ENOMEM;
568 
569 	res.name = sch56xx_pdev->name;
570 	err = acpi_check_resource_conflict(&res);
571 	if (err)
572 		goto exit_device_put;
573 
574 	err = platform_device_add_resources(sch56xx_pdev, &res, 1);
575 	if (err) {
576 		pr_err("Device resource addition failed\n");
577 		goto exit_device_put;
578 	}
579 
580 	err = platform_device_add(sch56xx_pdev);
581 	if (err) {
582 		pr_err("Device addition failed\n");
583 		goto exit_device_put;
584 	}
585 
586 	return 0;
587 
588 exit_device_put:
589 	platform_device_put(sch56xx_pdev);
590 
591 	return err;
592 }
593 
594 static int __init sch56xx_init(void)
595 {
596 	int err;
597 	unsigned short address;
598 	const char *name;
599 
600 	err = sch56xx_find(0x4e, &address, &name);
601 	if (err)
602 		err = sch56xx_find(0x2e, &address, &name);
603 	if (err)
604 		return err;
605 
606 	return sch56xx_device_add(address, name);
607 }
608 
609 static void __exit sch56xx_exit(void)
610 {
611 	platform_device_unregister(sch56xx_pdev);
612 }
613 
614 MODULE_DESCRIPTION("SMSC SCH56xx Hardware Monitoring Common Code");
615 MODULE_AUTHOR("Hans de Goede <hdegoede@redhat.com>");
616 MODULE_LICENSE("GPL");
617 
618 module_init(sch56xx_init);
619 module_exit(sch56xx_exit);
620