1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3 * Driver for the CS5535/CS5536 Multi-Function General Purpose Timers (MFGPT)
4 *
5 * Copyright (C) 2006, Advanced Micro Devices, Inc.
6 * Copyright (C) 2007 Andres Salomon <dilinger@debian.org>
7 * Copyright (C) 2009 Andres Salomon <dilinger@collabora.co.uk>
8 *
9 * The MFGPTs are documented in AMD Geode CS5536 Companion Device Data Book.
10 */
11
12 #include <linux/kernel.h>
13 #include <linux/spinlock.h>
14 #include <linux/interrupt.h>
15 #include <linux/module.h>
16 #include <linux/platform_device.h>
17 #include <linux/cs5535.h>
18 #include <linux/slab.h>
19
20 #define DRV_NAME "cs5535-mfgpt"
21
22 static int mfgpt_reset_timers;
23 module_param_named(mfgptfix, mfgpt_reset_timers, int, 0644);
24 MODULE_PARM_DESC(mfgptfix, "Try to reset the MFGPT timers during init; "
25 "required by some broken BIOSes (ie, TinyBIOS < 0.99) or kexec "
26 "(1 = reset the MFGPT using an undocumented bit, "
27 "2 = perform a soft reset by unconfiguring all timers); "
28 "use what works best for you.");
29
30 struct cs5535_mfgpt_timer {
31 struct cs5535_mfgpt_chip *chip;
32 int nr;
33 };
34
35 static struct cs5535_mfgpt_chip {
36 DECLARE_BITMAP(avail, MFGPT_MAX_TIMERS);
37 resource_size_t base;
38
39 struct platform_device *pdev;
40 spinlock_t lock;
41 int initialized;
42 } cs5535_mfgpt_chip;
43
cs5535_mfgpt_toggle_event(struct cs5535_mfgpt_timer * timer,int cmp,int event,int enable)44 int cs5535_mfgpt_toggle_event(struct cs5535_mfgpt_timer *timer, int cmp,
45 int event, int enable)
46 {
47 uint32_t msr, mask, value, dummy;
48 int shift = (cmp == MFGPT_CMP1) ? 0 : 8;
49
50 if (!timer) {
51 WARN_ON(1);
52 return -EIO;
53 }
54
55 /*
56 * The register maps for these are described in sections 6.17.1.x of
57 * the AMD Geode CS5536 Companion Device Data Book.
58 */
59 switch (event) {
60 case MFGPT_EVENT_RESET:
61 /*
62 * XXX: According to the docs, we cannot reset timers above
63 * 6; that is, resets for 7 and 8 will be ignored. Is this
64 * a problem? -dilinger
65 */
66 msr = MSR_MFGPT_NR;
67 mask = 1 << (timer->nr + 24);
68 break;
69
70 case MFGPT_EVENT_NMI:
71 msr = MSR_MFGPT_NR;
72 mask = 1 << (timer->nr + shift);
73 break;
74
75 case MFGPT_EVENT_IRQ:
76 msr = MSR_MFGPT_IRQ;
77 mask = 1 << (timer->nr + shift);
78 break;
79
80 default:
81 return -EIO;
82 }
83
84 rdmsr(msr, value, dummy);
85
86 if (enable)
87 value |= mask;
88 else
89 value &= ~mask;
90
91 wrmsr(msr, value, dummy);
92 return 0;
93 }
94 EXPORT_SYMBOL_GPL(cs5535_mfgpt_toggle_event);
95
cs5535_mfgpt_set_irq(struct cs5535_mfgpt_timer * timer,int cmp,int * irq,int enable)96 int cs5535_mfgpt_set_irq(struct cs5535_mfgpt_timer *timer, int cmp, int *irq,
97 int enable)
98 {
99 uint32_t zsel, lpc, dummy;
100 int shift;
101
102 if (!timer) {
103 WARN_ON(1);
104 return -EIO;
105 }
106
107 /*
108 * Unfortunately, MFGPTs come in pairs sharing their IRQ lines. If VSA
109 * is using the same CMP of the timer's Siamese twin, the IRQ is set to
110 * 2, and we mustn't use nor change it.
111 * XXX: Likewise, 2 Linux drivers might clash if the 2nd overwrites the
112 * IRQ of the 1st. This can only happen if forcing an IRQ, calling this
113 * with *irq==0 is safe. Currently there _are_ no 2 drivers.
114 */
115 rdmsr(MSR_PIC_ZSEL_LOW, zsel, dummy);
116 shift = ((cmp == MFGPT_CMP1 ? 0 : 4) + timer->nr % 4) * 4;
117 if (((zsel >> shift) & 0xF) == 2)
118 return -EIO;
119
120 /* Choose IRQ: if none supplied, keep IRQ already set or use default */
121 if (!*irq)
122 *irq = (zsel >> shift) & 0xF;
123 if (!*irq)
124 *irq = CONFIG_CS5535_MFGPT_DEFAULT_IRQ;
125
126 /* Can't use IRQ if it's 0 (=disabled), 2, or routed to LPC */
127 if (*irq < 1 || *irq == 2 || *irq > 15)
128 return -EIO;
129 rdmsr(MSR_PIC_IRQM_LPC, lpc, dummy);
130 if (lpc & (1 << *irq))
131 return -EIO;
132
133 /* All chosen and checked - go for it */
134 if (cs5535_mfgpt_toggle_event(timer, cmp, MFGPT_EVENT_IRQ, enable))
135 return -EIO;
136 if (enable) {
137 zsel = (zsel & ~(0xF << shift)) | (*irq << shift);
138 wrmsr(MSR_PIC_ZSEL_LOW, zsel, dummy);
139 }
140
141 return 0;
142 }
143 EXPORT_SYMBOL_GPL(cs5535_mfgpt_set_irq);
144
cs5535_mfgpt_alloc_timer(int timer_nr,int domain)145 struct cs5535_mfgpt_timer *cs5535_mfgpt_alloc_timer(int timer_nr, int domain)
146 {
147 struct cs5535_mfgpt_chip *mfgpt = &cs5535_mfgpt_chip;
148 struct cs5535_mfgpt_timer *timer = NULL;
149 unsigned long flags;
150 int max;
151
152 if (!mfgpt->initialized)
153 goto done;
154
155 /* only allocate timers from the working domain if requested */
156 if (domain == MFGPT_DOMAIN_WORKING)
157 max = 6;
158 else
159 max = MFGPT_MAX_TIMERS;
160
161 if (timer_nr >= max) {
162 /* programmer error. silly programmers! */
163 WARN_ON(1);
164 goto done;
165 }
166
167 spin_lock_irqsave(&mfgpt->lock, flags);
168 if (timer_nr < 0) {
169 unsigned long t;
170
171 /* try to find any available timer */
172 t = find_first_bit(mfgpt->avail, max);
173 /* set timer_nr to -1 if no timers available */
174 timer_nr = t < max ? (int) t : -1;
175 } else {
176 /* check if the requested timer's available */
177 if (!test_bit(timer_nr, mfgpt->avail))
178 timer_nr = -1;
179 }
180
181 if (timer_nr >= 0)
182 /* if timer_nr is not -1, it's an available timer */
183 __clear_bit(timer_nr, mfgpt->avail);
184 spin_unlock_irqrestore(&mfgpt->lock, flags);
185
186 if (timer_nr < 0)
187 goto done;
188
189 timer = kmalloc(sizeof(*timer), GFP_KERNEL);
190 if (!timer) {
191 /* aw hell */
192 spin_lock_irqsave(&mfgpt->lock, flags);
193 __set_bit(timer_nr, mfgpt->avail);
194 spin_unlock_irqrestore(&mfgpt->lock, flags);
195 goto done;
196 }
197 timer->chip = mfgpt;
198 timer->nr = timer_nr;
199 dev_info(&mfgpt->pdev->dev, "registered timer %d\n", timer_nr);
200
201 done:
202 return timer;
203 }
204 EXPORT_SYMBOL_GPL(cs5535_mfgpt_alloc_timer);
205
206 /*
207 * XXX: This frees the timer memory, but never resets the actual hardware
208 * timer. The old geode_mfgpt code did this; it would be good to figure
209 * out a way to actually release the hardware timer. See comments below.
210 */
cs5535_mfgpt_free_timer(struct cs5535_mfgpt_timer * timer)211 void cs5535_mfgpt_free_timer(struct cs5535_mfgpt_timer *timer)
212 {
213 unsigned long flags;
214 uint16_t val;
215
216 /* timer can be made available again only if never set up */
217 val = cs5535_mfgpt_read(timer, MFGPT_REG_SETUP);
218 if (!(val & MFGPT_SETUP_SETUP)) {
219 spin_lock_irqsave(&timer->chip->lock, flags);
220 __set_bit(timer->nr, timer->chip->avail);
221 spin_unlock_irqrestore(&timer->chip->lock, flags);
222 }
223
224 kfree(timer);
225 }
226 EXPORT_SYMBOL_GPL(cs5535_mfgpt_free_timer);
227
cs5535_mfgpt_read(struct cs5535_mfgpt_timer * timer,uint16_t reg)228 uint16_t cs5535_mfgpt_read(struct cs5535_mfgpt_timer *timer, uint16_t reg)
229 {
230 return inw(timer->chip->base + reg + (timer->nr * 8));
231 }
232 EXPORT_SYMBOL_GPL(cs5535_mfgpt_read);
233
cs5535_mfgpt_write(struct cs5535_mfgpt_timer * timer,uint16_t reg,uint16_t value)234 void cs5535_mfgpt_write(struct cs5535_mfgpt_timer *timer, uint16_t reg,
235 uint16_t value)
236 {
237 outw(value, timer->chip->base + reg + (timer->nr * 8));
238 }
239 EXPORT_SYMBOL_GPL(cs5535_mfgpt_write);
240
241 /*
242 * This is a sledgehammer that resets all MFGPT timers. This is required by
243 * some broken BIOSes which leave the system in an unstable state
244 * (TinyBIOS 0.98, for example; fixed in 0.99). It's uncertain as to
245 * whether or not this secret MSR can be used to release individual timers.
246 * Jordan tells me that he and Mitch once played w/ it, but it's unclear
247 * what the results of that were (and they experienced some instability).
248 */
reset_all_timers(void)249 static void reset_all_timers(void)
250 {
251 uint32_t val, dummy;
252
253 /* The following undocumented bit resets the MFGPT timers */
254 val = 0xFF; dummy = 0;
255 wrmsr(MSR_MFGPT_SETUP, val, dummy);
256 }
257
258 /*
259 * This is another sledgehammer to reset all MFGPT timers.
260 * Instead of using the undocumented bit method it clears
261 * IRQ, NMI and RESET settings.
262 */
soft_reset(void)263 static void soft_reset(void)
264 {
265 int i;
266 struct cs5535_mfgpt_timer t;
267
268 for (i = 0; i < MFGPT_MAX_TIMERS; i++) {
269 t.nr = i;
270
271 cs5535_mfgpt_toggle_event(&t, MFGPT_CMP1, MFGPT_EVENT_RESET, 0);
272 cs5535_mfgpt_toggle_event(&t, MFGPT_CMP2, MFGPT_EVENT_RESET, 0);
273 cs5535_mfgpt_toggle_event(&t, MFGPT_CMP1, MFGPT_EVENT_NMI, 0);
274 cs5535_mfgpt_toggle_event(&t, MFGPT_CMP2, MFGPT_EVENT_NMI, 0);
275 cs5535_mfgpt_toggle_event(&t, MFGPT_CMP1, MFGPT_EVENT_IRQ, 0);
276 cs5535_mfgpt_toggle_event(&t, MFGPT_CMP2, MFGPT_EVENT_IRQ, 0);
277 }
278 }
279
280 /*
281 * Check whether any MFGPTs are available for the kernel to use. In most
282 * cases, firmware that uses AMD's VSA code will claim all timers during
283 * bootup; we certainly don't want to take them if they're already in use.
284 * In other cases (such as with VSAless OpenFirmware), the system firmware
285 * leaves timers available for us to use.
286 */
scan_timers(struct cs5535_mfgpt_chip * mfgpt)287 static int scan_timers(struct cs5535_mfgpt_chip *mfgpt)
288 {
289 struct cs5535_mfgpt_timer timer = { .chip = mfgpt };
290 unsigned long flags;
291 int timers = 0;
292 uint16_t val;
293 int i;
294
295 /* bios workaround */
296 if (mfgpt_reset_timers == 1)
297 reset_all_timers();
298 else if (mfgpt_reset_timers == 2)
299 soft_reset();
300
301 /* just to be safe, protect this section w/ lock */
302 spin_lock_irqsave(&mfgpt->lock, flags);
303 for (i = 0; i < MFGPT_MAX_TIMERS; i++) {
304 timer.nr = i;
305 val = cs5535_mfgpt_read(&timer, MFGPT_REG_SETUP);
306 if (!(val & MFGPT_SETUP_SETUP) || mfgpt_reset_timers == 2) {
307 __set_bit(i, mfgpt->avail);
308 timers++;
309 }
310 }
311 spin_unlock_irqrestore(&mfgpt->lock, flags);
312
313 return timers;
314 }
315
cs5535_mfgpt_probe(struct platform_device * pdev)316 static int cs5535_mfgpt_probe(struct platform_device *pdev)
317 {
318 struct resource *res;
319 int err = -EIO, t;
320
321 if (mfgpt_reset_timers < 0 || mfgpt_reset_timers > 2) {
322 dev_err(&pdev->dev, "Bad mfgpt_reset_timers value: %i\n",
323 mfgpt_reset_timers);
324 goto done;
325 }
326
327 /* There are two ways to get the MFGPT base address; one is by
328 * fetching it from MSR_LBAR_MFGPT, the other is by reading the
329 * PCI BAR info. The latter method is easier (especially across
330 * different architectures), so we'll stick with that for now. If
331 * it turns out to be unreliable in the face of crappy BIOSes, we
332 * can always go back to using MSRs.. */
333
334 res = platform_get_resource(pdev, IORESOURCE_IO, 0);
335 if (!res) {
336 dev_err(&pdev->dev, "can't fetch device resource info\n");
337 goto done;
338 }
339
340 if (!request_region(res->start, resource_size(res), pdev->name)) {
341 dev_err(&pdev->dev, "can't request region\n");
342 goto done;
343 }
344
345 /* set up the driver-specific struct */
346 cs5535_mfgpt_chip.base = res->start;
347 cs5535_mfgpt_chip.pdev = pdev;
348 spin_lock_init(&cs5535_mfgpt_chip.lock);
349
350 dev_info(&pdev->dev, "reserved resource region %pR\n", res);
351
352 /* detect the available timers */
353 t = scan_timers(&cs5535_mfgpt_chip);
354 dev_info(&pdev->dev, "%d MFGPT timers available\n", t);
355 cs5535_mfgpt_chip.initialized = 1;
356 return 0;
357
358 done:
359 return err;
360 }
361
362 static struct platform_driver cs5535_mfgpt_driver = {
363 .driver = {
364 .name = DRV_NAME,
365 },
366 .probe = cs5535_mfgpt_probe,
367 };
368
369
cs5535_mfgpt_init(void)370 static int __init cs5535_mfgpt_init(void)
371 {
372 return platform_driver_register(&cs5535_mfgpt_driver);
373 }
374
375 module_init(cs5535_mfgpt_init);
376
377 MODULE_AUTHOR("Andres Salomon <dilinger@queued.net>");
378 MODULE_DESCRIPTION("CS5535/CS5536 MFGPT timer driver");
379 MODULE_LICENSE("GPL");
380 MODULE_ALIAS("platform:" DRV_NAME);
381