1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /***************************************************************************
3  *   Copyright (C) 2010-2012 Hans de Goede <hdegoede@redhat.com>           *
4  *                                                                         *
5  ***************************************************************************/
6 
7 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
8 
9 #include <linux/module.h>
10 #include <linux/init.h>
11 #include <linux/platform_device.h>
12 #include <linux/err.h>
13 #include <linux/io.h>
14 #include <linux/acpi.h>
15 #include <linux/delay.h>
16 #include <linux/fs.h>
17 #include <linux/watchdog.h>
18 #include <linux/uaccess.h>
19 #include <linux/slab.h>
20 #include "sch56xx-common.h"
21 
22 /* Insmod parameters */
23 static bool nowayout = WATCHDOG_NOWAYOUT;
24 module_param(nowayout, bool, 0);
25 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="
26 	__MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
27 
28 #define SIO_SCH56XX_LD_EM	0x0C	/* Embedded uController Logical Dev */
29 #define SIO_UNLOCK_KEY		0x55	/* Key to enable Super-I/O */
30 #define SIO_LOCK_KEY		0xAA	/* Key to disable Super-I/O */
31 
32 #define SIO_REG_LDSEL		0x07	/* Logical device select */
33 #define SIO_REG_DEVID		0x20	/* Device ID */
34 #define SIO_REG_ENABLE		0x30	/* Logical device enable */
35 #define SIO_REG_ADDR		0x66	/* Logical device address (2 bytes) */
36 
37 #define SIO_SCH5627_ID		0xC6	/* Chipset ID */
38 #define SIO_SCH5636_ID		0xC7	/* Chipset ID */
39 
40 #define REGION_LENGTH		10
41 
42 #define SCH56XX_CMD_READ	0x02
43 #define SCH56XX_CMD_WRITE	0x03
44 
45 /* Watchdog registers */
46 #define SCH56XX_REG_WDOG_PRESET		0x58B
47 #define SCH56XX_REG_WDOG_CONTROL	0x58C
48 #define SCH56XX_WDOG_TIME_BASE_SEC	0x01
49 #define SCH56XX_REG_WDOG_OUTPUT_ENABLE	0x58E
50 #define SCH56XX_WDOG_OUTPUT_ENABLE	0x02
51 
52 struct sch56xx_watchdog_data {
53 	u16 addr;
54 	struct mutex *io_lock;
55 	struct watchdog_info wdinfo;
56 	struct watchdog_device wddev;
57 	u8 watchdog_preset;
58 	u8 watchdog_control;
59 	u8 watchdog_output_enable;
60 };
61 
62 static struct platform_device *sch56xx_pdev;
63 
64 /* Super I/O functions */
65 static inline int superio_inb(int base, int reg)
66 {
67 	outb(reg, base);
68 	return inb(base + 1);
69 }
70 
71 static inline int superio_enter(int base)
72 {
73 	/* Don't step on other drivers' I/O space by accident */
74 	if (!request_muxed_region(base, 2, "sch56xx")) {
75 		pr_err("I/O address 0x%04x already in use\n", base);
76 		return -EBUSY;
77 	}
78 
79 	outb(SIO_UNLOCK_KEY, base);
80 
81 	return 0;
82 }
83 
84 static inline void superio_select(int base, int ld)
85 {
86 	outb(SIO_REG_LDSEL, base);
87 	outb(ld, base + 1);
88 }
89 
90 static inline void superio_exit(int base)
91 {
92 	outb(SIO_LOCK_KEY, base);
93 	release_region(base, 2);
94 }
95 
96 static int sch56xx_send_cmd(u16 addr, u8 cmd, u16 reg, u8 v)
97 {
98 	u8 val;
99 	int i;
100 	/*
101 	 * According to SMSC for the commands we use the maximum time for
102 	 * the EM to respond is 15 ms, but testing shows in practice it
103 	 * responds within 15-32 reads, so we first busy poll, and if
104 	 * that fails sleep a bit and try again until we are way past
105 	 * the 15 ms maximum response time.
106 	 */
107 	const int max_busy_polls = 64;
108 	const int max_lazy_polls = 32;
109 
110 	/* (Optional) Write-Clear the EC to Host Mailbox Register */
111 	val = inb(addr + 1);
112 	outb(val, addr + 1);
113 
114 	/* Set Mailbox Address Pointer to first location in Region 1 */
115 	outb(0x00, addr + 2);
116 	outb(0x80, addr + 3);
117 
118 	/* Write Request Packet Header */
119 	outb(cmd, addr + 4); /* VREG Access Type read:0x02 write:0x03 */
120 	outb(0x01, addr + 5); /* # of Entries: 1 Byte (8-bit) */
121 	outb(0x04, addr + 2); /* Mailbox AP to first data entry loc. */
122 
123 	/* Write Value field */
124 	if (cmd == SCH56XX_CMD_WRITE)
125 		outb(v, addr + 4);
126 
127 	/* Write Address field */
128 	outb(reg & 0xff, addr + 6);
129 	outb(reg >> 8, addr + 7);
130 
131 	/* Execute the Random Access Command */
132 	outb(0x01, addr); /* Write 01h to the Host-to-EC register */
133 
134 	/* EM Interface Polling "Algorithm" */
135 	for (i = 0; i < max_busy_polls + max_lazy_polls; i++) {
136 		if (i >= max_busy_polls)
137 			msleep(1);
138 		/* Read Interrupt source Register */
139 		val = inb(addr + 8);
140 		/* Write Clear the interrupt source bits */
141 		if (val)
142 			outb(val, addr + 8);
143 		/* Command Completed ? */
144 		if (val & 0x01)
145 			break;
146 	}
147 	if (i == max_busy_polls + max_lazy_polls) {
148 		pr_err("Max retries exceeded reading virtual register 0x%04hx (%d)\n",
149 		       reg, 1);
150 		return -EIO;
151 	}
152 
153 	/*
154 	 * According to SMSC we may need to retry this, but sofar I've always
155 	 * seen this succeed in 1 try.
156 	 */
157 	for (i = 0; i < max_busy_polls; i++) {
158 		/* Read EC-to-Host Register */
159 		val = inb(addr + 1);
160 		/* Command Completed ? */
161 		if (val == 0x01)
162 			break;
163 
164 		if (i == 0)
165 			pr_warn("EC reports: 0x%02x reading virtual register 0x%04hx\n",
166 				(unsigned int)val, reg);
167 	}
168 	if (i == max_busy_polls) {
169 		pr_err("Max retries exceeded reading virtual register 0x%04hx (%d)\n",
170 		       reg, 2);
171 		return -EIO;
172 	}
173 
174 	/*
175 	 * According to the SMSC app note we should now do:
176 	 *
177 	 * Set Mailbox Address Pointer to first location in Region 1 *
178 	 * outb(0x00, addr + 2);
179 	 * outb(0x80, addr + 3);
180 	 *
181 	 * But if we do that things don't work, so let's not.
182 	 */
183 
184 	/* Read Value field */
185 	if (cmd == SCH56XX_CMD_READ)
186 		return inb(addr + 4);
187 
188 	return 0;
189 }
190 
191 int sch56xx_read_virtual_reg(u16 addr, u16 reg)
192 {
193 	return sch56xx_send_cmd(addr, SCH56XX_CMD_READ, reg, 0);
194 }
195 EXPORT_SYMBOL(sch56xx_read_virtual_reg);
196 
197 int sch56xx_write_virtual_reg(u16 addr, u16 reg, u8 val)
198 {
199 	return sch56xx_send_cmd(addr, SCH56XX_CMD_WRITE, reg, val);
200 }
201 EXPORT_SYMBOL(sch56xx_write_virtual_reg);
202 
203 int sch56xx_read_virtual_reg16(u16 addr, u16 reg)
204 {
205 	int lsb, msb;
206 
207 	/* Read LSB first, this will cause the matching MSB to be latched */
208 	lsb = sch56xx_read_virtual_reg(addr, reg);
209 	if (lsb < 0)
210 		return lsb;
211 
212 	msb = sch56xx_read_virtual_reg(addr, reg + 1);
213 	if (msb < 0)
214 		return msb;
215 
216 	return lsb | (msb << 8);
217 }
218 EXPORT_SYMBOL(sch56xx_read_virtual_reg16);
219 
220 int sch56xx_read_virtual_reg12(u16 addr, u16 msb_reg, u16 lsn_reg,
221 			       int high_nibble)
222 {
223 	int msb, lsn;
224 
225 	/* Read MSB first, this will cause the matching LSN to be latched */
226 	msb = sch56xx_read_virtual_reg(addr, msb_reg);
227 	if (msb < 0)
228 		return msb;
229 
230 	lsn = sch56xx_read_virtual_reg(addr, lsn_reg);
231 	if (lsn < 0)
232 		return lsn;
233 
234 	if (high_nibble)
235 		return (msb << 4) | (lsn >> 4);
236 	else
237 		return (msb << 4) | (lsn & 0x0f);
238 }
239 EXPORT_SYMBOL(sch56xx_read_virtual_reg12);
240 
241 /*
242  * Watchdog routines
243  */
244 
245 static int watchdog_set_timeout(struct watchdog_device *wddev,
246 				unsigned int timeout)
247 {
248 	struct sch56xx_watchdog_data *data = watchdog_get_drvdata(wddev);
249 	unsigned int resolution;
250 	u8 control;
251 	int ret;
252 
253 	/* 1 second or 60 second resolution? */
254 	if (timeout <= 255)
255 		resolution = 1;
256 	else
257 		resolution = 60;
258 
259 	if (timeout < resolution || timeout > (resolution * 255))
260 		return -EINVAL;
261 
262 	if (resolution == 1)
263 		control = data->watchdog_control | SCH56XX_WDOG_TIME_BASE_SEC;
264 	else
265 		control = data->watchdog_control & ~SCH56XX_WDOG_TIME_BASE_SEC;
266 
267 	if (data->watchdog_control != control) {
268 		mutex_lock(data->io_lock);
269 		ret = sch56xx_write_virtual_reg(data->addr,
270 						SCH56XX_REG_WDOG_CONTROL,
271 						control);
272 		mutex_unlock(data->io_lock);
273 		if (ret)
274 			return ret;
275 
276 		data->watchdog_control = control;
277 	}
278 
279 	/*
280 	 * Remember new timeout value, but do not write as that (re)starts
281 	 * the watchdog countdown.
282 	 */
283 	data->watchdog_preset = DIV_ROUND_UP(timeout, resolution);
284 	wddev->timeout = data->watchdog_preset * resolution;
285 
286 	return 0;
287 }
288 
289 static int watchdog_start(struct watchdog_device *wddev)
290 {
291 	struct sch56xx_watchdog_data *data = watchdog_get_drvdata(wddev);
292 	int ret;
293 	u8 val;
294 
295 	/*
296 	 * The sch56xx's watchdog cannot really be started / stopped
297 	 * it is always running, but we can avoid the timer expiring
298 	 * from causing a system reset by clearing the output enable bit.
299 	 *
300 	 * The sch56xx's watchdog will set the watchdog event bit, bit 0
301 	 * of the second interrupt source register (at base-address + 9),
302 	 * when the timer expires.
303 	 *
304 	 * This will only cause a system reset if the 0-1 flank happens when
305 	 * output enable is true. Setting output enable after the flank will
306 	 * not cause a reset, nor will the timer expiring a second time.
307 	 * This means we must clear the watchdog event bit in case it is set.
308 	 *
309 	 * The timer may still be running (after a recent watchdog_stop) and
310 	 * mere milliseconds away from expiring, so the timer must be reset
311 	 * first!
312 	 */
313 
314 	mutex_lock(data->io_lock);
315 
316 	/* 1. Reset the watchdog countdown counter */
317 	ret = sch56xx_write_virtual_reg(data->addr, SCH56XX_REG_WDOG_PRESET,
318 					data->watchdog_preset);
319 	if (ret)
320 		goto leave;
321 
322 	/* 2. Enable output */
323 	val = data->watchdog_output_enable | SCH56XX_WDOG_OUTPUT_ENABLE;
324 	ret = sch56xx_write_virtual_reg(data->addr,
325 					SCH56XX_REG_WDOG_OUTPUT_ENABLE, val);
326 	if (ret)
327 		goto leave;
328 
329 	data->watchdog_output_enable = val;
330 
331 	/* 3. Clear the watchdog event bit if set */
332 	val = inb(data->addr + 9);
333 	if (val & 0x01)
334 		outb(0x01, data->addr + 9);
335 
336 leave:
337 	mutex_unlock(data->io_lock);
338 	return ret;
339 }
340 
341 static int watchdog_trigger(struct watchdog_device *wddev)
342 {
343 	struct sch56xx_watchdog_data *data = watchdog_get_drvdata(wddev);
344 	int ret;
345 
346 	/* Reset the watchdog countdown counter */
347 	mutex_lock(data->io_lock);
348 	ret = sch56xx_write_virtual_reg(data->addr, SCH56XX_REG_WDOG_PRESET,
349 					data->watchdog_preset);
350 	mutex_unlock(data->io_lock);
351 
352 	return ret;
353 }
354 
355 static int watchdog_stop(struct watchdog_device *wddev)
356 {
357 	struct sch56xx_watchdog_data *data = watchdog_get_drvdata(wddev);
358 	int ret = 0;
359 	u8 val;
360 
361 	val = data->watchdog_output_enable & ~SCH56XX_WDOG_OUTPUT_ENABLE;
362 	mutex_lock(data->io_lock);
363 	ret = sch56xx_write_virtual_reg(data->addr,
364 					SCH56XX_REG_WDOG_OUTPUT_ENABLE, val);
365 	mutex_unlock(data->io_lock);
366 	if (ret)
367 		return ret;
368 
369 	data->watchdog_output_enable = val;
370 	return 0;
371 }
372 
373 static const struct watchdog_ops watchdog_ops = {
374 	.owner		= THIS_MODULE,
375 	.start		= watchdog_start,
376 	.stop		= watchdog_stop,
377 	.ping		= watchdog_trigger,
378 	.set_timeout	= watchdog_set_timeout,
379 };
380 
381 void sch56xx_watchdog_register(struct device *parent, u16 addr, u32 revision,
382 			       struct mutex *io_lock, int check_enabled)
383 {
384 	struct sch56xx_watchdog_data *data;
385 	int err, control, output_enable;
386 
387 	/* Cache the watchdog registers */
388 	mutex_lock(io_lock);
389 	control =
390 		sch56xx_read_virtual_reg(addr, SCH56XX_REG_WDOG_CONTROL);
391 	output_enable =
392 		sch56xx_read_virtual_reg(addr, SCH56XX_REG_WDOG_OUTPUT_ENABLE);
393 	mutex_unlock(io_lock);
394 
395 	if (control < 0)
396 		return;
397 	if (output_enable < 0)
398 		return;
399 	if (check_enabled && !(output_enable & SCH56XX_WDOG_OUTPUT_ENABLE)) {
400 		pr_warn("Watchdog not enabled by BIOS, not registering\n");
401 		return;
402 	}
403 
404 	data = devm_kzalloc(parent, sizeof(struct sch56xx_watchdog_data), GFP_KERNEL);
405 	if (!data)
406 		return;
407 
408 	data->addr = addr;
409 	data->io_lock = io_lock;
410 
411 	strscpy(data->wdinfo.identity, "sch56xx watchdog", sizeof(data->wdinfo.identity));
412 	data->wdinfo.firmware_version = revision;
413 	data->wdinfo.options = WDIOF_KEEPALIVEPING | WDIOF_SETTIMEOUT;
414 	if (!nowayout)
415 		data->wdinfo.options |= WDIOF_MAGICCLOSE;
416 
417 	data->wddev.info = &data->wdinfo;
418 	data->wddev.ops = &watchdog_ops;
419 	data->wddev.parent = parent;
420 	data->wddev.timeout = 60;
421 	data->wddev.min_timeout = 1;
422 	data->wddev.max_timeout = 255 * 60;
423 	watchdog_set_nowayout(&data->wddev, nowayout);
424 	if (output_enable & SCH56XX_WDOG_OUTPUT_ENABLE)
425 		set_bit(WDOG_ACTIVE, &data->wddev.status);
426 
427 	/* Since the watchdog uses a downcounter there is no register to read
428 	   the BIOS set timeout from (if any was set at all) ->
429 	   Choose a preset which will give us a 1 minute timeout */
430 	if (control & SCH56XX_WDOG_TIME_BASE_SEC)
431 		data->watchdog_preset = 60; /* seconds */
432 	else
433 		data->watchdog_preset = 1; /* minute */
434 
435 	data->watchdog_control = control;
436 	data->watchdog_output_enable = output_enable;
437 
438 	watchdog_set_drvdata(&data->wddev, data);
439 	err = devm_watchdog_register_device(parent, &data->wddev);
440 	if (err) {
441 		pr_err("Registering watchdog chardev: %d\n", err);
442 		devm_kfree(parent, data);
443 	}
444 }
445 EXPORT_SYMBOL(sch56xx_watchdog_register);
446 
447 /*
448  * platform dev find, add and remove functions
449  */
450 
451 static int __init sch56xx_find(int sioaddr, const char **name)
452 {
453 	u8 devid;
454 	unsigned short address;
455 	int err;
456 
457 	err = superio_enter(sioaddr);
458 	if (err)
459 		return err;
460 
461 	devid = superio_inb(sioaddr, SIO_REG_DEVID);
462 	switch (devid) {
463 	case SIO_SCH5627_ID:
464 		*name = "sch5627";
465 		break;
466 	case SIO_SCH5636_ID:
467 		*name = "sch5636";
468 		break;
469 	default:
470 		pr_debug("Unsupported device id: 0x%02x\n",
471 			 (unsigned int)devid);
472 		err = -ENODEV;
473 		goto exit;
474 	}
475 
476 	superio_select(sioaddr, SIO_SCH56XX_LD_EM);
477 
478 	if (!(superio_inb(sioaddr, SIO_REG_ENABLE) & 0x01)) {
479 		pr_warn("Device not activated\n");
480 		err = -ENODEV;
481 		goto exit;
482 	}
483 
484 	/*
485 	 * Warning the order of the low / high byte is the other way around
486 	 * as on most other superio devices!!
487 	 */
488 	address = superio_inb(sioaddr, SIO_REG_ADDR) |
489 		   superio_inb(sioaddr, SIO_REG_ADDR + 1) << 8;
490 	if (address == 0) {
491 		pr_warn("Base address not set\n");
492 		err = -ENODEV;
493 		goto exit;
494 	}
495 	err = address;
496 
497 exit:
498 	superio_exit(sioaddr);
499 	return err;
500 }
501 
502 static int __init sch56xx_device_add(int address, const char *name)
503 {
504 	struct resource res = {
505 		.start	= address,
506 		.end	= address + REGION_LENGTH - 1,
507 		.name	= name,
508 		.flags	= IORESOURCE_IO,
509 	};
510 	int err;
511 
512 	err = acpi_check_resource_conflict(&res);
513 	if (err)
514 		return err;
515 
516 	sch56xx_pdev = platform_device_register_simple(name, -1, &res, 1);
517 
518 	return PTR_ERR_OR_ZERO(sch56xx_pdev);
519 }
520 
521 static int __init sch56xx_init(void)
522 {
523 	int address;
524 	const char *name = NULL;
525 
526 	address = sch56xx_find(0x4e, &name);
527 	if (address < 0)
528 		address = sch56xx_find(0x2e, &name);
529 	if (address < 0)
530 		return address;
531 
532 	return sch56xx_device_add(address, name);
533 }
534 
535 static void __exit sch56xx_exit(void)
536 {
537 	platform_device_unregister(sch56xx_pdev);
538 }
539 
540 MODULE_DESCRIPTION("SMSC SCH56xx Hardware Monitoring Common Code");
541 MODULE_AUTHOR("Hans de Goede <hdegoede@redhat.com>");
542 MODULE_LICENSE("GPL");
543 
544 module_init(sch56xx_init);
545 module_exit(sch56xx_exit);
546