1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3 * Copyright 2016 IBM Corporation
4 *
5 * Joel Stanley <joel@jms.id.au>
6 */
7
8 #include <linux/delay.h>
9 #include <linux/io.h>
10 #include <linux/kernel.h>
11 #include <linux/module.h>
12 #include <linux/of.h>
13 #include <linux/platform_device.h>
14 #include <linux/watchdog.h>
15
16 struct aspeed_wdt {
17 struct watchdog_device wdd;
18 void __iomem *base;
19 u32 ctrl;
20 };
21
22 struct aspeed_wdt_config {
23 u32 ext_pulse_width_mask;
24 };
25
26 static const struct aspeed_wdt_config ast2400_config = {
27 .ext_pulse_width_mask = 0xff,
28 };
29
30 static const struct aspeed_wdt_config ast2500_config = {
31 .ext_pulse_width_mask = 0xfffff,
32 };
33
34 static const struct of_device_id aspeed_wdt_of_table[] = {
35 { .compatible = "aspeed,ast2400-wdt", .data = &ast2400_config },
36 { .compatible = "aspeed,ast2500-wdt", .data = &ast2500_config },
37 { .compatible = "aspeed,ast2600-wdt", .data = &ast2500_config },
38 { },
39 };
40 MODULE_DEVICE_TABLE(of, aspeed_wdt_of_table);
41
42 #define WDT_STATUS 0x00
43 #define WDT_RELOAD_VALUE 0x04
44 #define WDT_RESTART 0x08
45 #define WDT_CTRL 0x0C
46 #define WDT_CTRL_BOOT_SECONDARY BIT(7)
47 #define WDT_CTRL_RESET_MODE_SOC (0x00 << 5)
48 #define WDT_CTRL_RESET_MODE_FULL_CHIP (0x01 << 5)
49 #define WDT_CTRL_RESET_MODE_ARM_CPU (0x10 << 5)
50 #define WDT_CTRL_1MHZ_CLK BIT(4)
51 #define WDT_CTRL_WDT_EXT BIT(3)
52 #define WDT_CTRL_WDT_INTR BIT(2)
53 #define WDT_CTRL_RESET_SYSTEM BIT(1)
54 #define WDT_CTRL_ENABLE BIT(0)
55 #define WDT_TIMEOUT_STATUS 0x10
56 #define WDT_TIMEOUT_STATUS_BOOT_SECONDARY BIT(1)
57 #define WDT_CLEAR_TIMEOUT_STATUS 0x14
58 #define WDT_CLEAR_TIMEOUT_AND_BOOT_CODE_SELECTION BIT(0)
59
60 /*
61 * WDT_RESET_WIDTH controls the characteristics of the external pulse (if
62 * enabled), specifically:
63 *
64 * * Pulse duration
65 * * Drive mode: push-pull vs open-drain
66 * * Polarity: Active high or active low
67 *
68 * Pulse duration configuration is available on both the AST2400 and AST2500,
69 * though the field changes between SoCs:
70 *
71 * AST2400: Bits 7:0
72 * AST2500: Bits 19:0
73 *
74 * This difference is captured in struct aspeed_wdt_config.
75 *
76 * The AST2500 exposes the drive mode and polarity options, but not in a
77 * regular fashion. For read purposes, bit 31 represents active high or low,
78 * and bit 30 represents push-pull or open-drain. With respect to write, magic
79 * values need to be written to the top byte to change the state of the drive
80 * mode and polarity bits. Any other value written to the top byte has no
81 * effect on the state of the drive mode or polarity bits. However, the pulse
82 * width value must be preserved (as desired) if written.
83 */
84 #define WDT_RESET_WIDTH 0x18
85 #define WDT_RESET_WIDTH_ACTIVE_HIGH BIT(31)
86 #define WDT_ACTIVE_HIGH_MAGIC (0xA5 << 24)
87 #define WDT_ACTIVE_LOW_MAGIC (0x5A << 24)
88 #define WDT_RESET_WIDTH_PUSH_PULL BIT(30)
89 #define WDT_PUSH_PULL_MAGIC (0xA8 << 24)
90 #define WDT_OPEN_DRAIN_MAGIC (0x8A << 24)
91
92 #define WDT_RESTART_MAGIC 0x4755
93
94 /* 32 bits at 1MHz, in milliseconds */
95 #define WDT_MAX_TIMEOUT_MS 4294967
96 #define WDT_DEFAULT_TIMEOUT 30
97 #define WDT_RATE_1MHZ 1000000
98
to_aspeed_wdt(struct watchdog_device * wdd)99 static struct aspeed_wdt *to_aspeed_wdt(struct watchdog_device *wdd)
100 {
101 return container_of(wdd, struct aspeed_wdt, wdd);
102 }
103
aspeed_wdt_enable(struct aspeed_wdt * wdt,int count)104 static void aspeed_wdt_enable(struct aspeed_wdt *wdt, int count)
105 {
106 wdt->ctrl |= WDT_CTRL_ENABLE;
107
108 writel(0, wdt->base + WDT_CTRL);
109 writel(count, wdt->base + WDT_RELOAD_VALUE);
110 writel(WDT_RESTART_MAGIC, wdt->base + WDT_RESTART);
111 writel(wdt->ctrl, wdt->base + WDT_CTRL);
112 }
113
aspeed_wdt_start(struct watchdog_device * wdd)114 static int aspeed_wdt_start(struct watchdog_device *wdd)
115 {
116 struct aspeed_wdt *wdt = to_aspeed_wdt(wdd);
117
118 aspeed_wdt_enable(wdt, wdd->timeout * WDT_RATE_1MHZ);
119
120 return 0;
121 }
122
aspeed_wdt_stop(struct watchdog_device * wdd)123 static int aspeed_wdt_stop(struct watchdog_device *wdd)
124 {
125 struct aspeed_wdt *wdt = to_aspeed_wdt(wdd);
126
127 wdt->ctrl &= ~WDT_CTRL_ENABLE;
128 writel(wdt->ctrl, wdt->base + WDT_CTRL);
129
130 return 0;
131 }
132
aspeed_wdt_ping(struct watchdog_device * wdd)133 static int aspeed_wdt_ping(struct watchdog_device *wdd)
134 {
135 struct aspeed_wdt *wdt = to_aspeed_wdt(wdd);
136
137 writel(WDT_RESTART_MAGIC, wdt->base + WDT_RESTART);
138
139 return 0;
140 }
141
aspeed_wdt_set_timeout(struct watchdog_device * wdd,unsigned int timeout)142 static int aspeed_wdt_set_timeout(struct watchdog_device *wdd,
143 unsigned int timeout)
144 {
145 struct aspeed_wdt *wdt = to_aspeed_wdt(wdd);
146 u32 actual;
147
148 wdd->timeout = timeout;
149
150 actual = min(timeout, wdd->max_hw_heartbeat_ms / 1000);
151
152 writel(actual * WDT_RATE_1MHZ, wdt->base + WDT_RELOAD_VALUE);
153 writel(WDT_RESTART_MAGIC, wdt->base + WDT_RESTART);
154
155 return 0;
156 }
157
aspeed_wdt_restart(struct watchdog_device * wdd,unsigned long action,void * data)158 static int aspeed_wdt_restart(struct watchdog_device *wdd,
159 unsigned long action, void *data)
160 {
161 struct aspeed_wdt *wdt = to_aspeed_wdt(wdd);
162
163 wdt->ctrl &= ~WDT_CTRL_BOOT_SECONDARY;
164 aspeed_wdt_enable(wdt, 128 * WDT_RATE_1MHZ / 1000);
165
166 mdelay(1000);
167
168 return 0;
169 }
170
171 /* access_cs0 shows if cs0 is accessible, hence the reverted bit */
access_cs0_show(struct device * dev,struct device_attribute * attr,char * buf)172 static ssize_t access_cs0_show(struct device *dev,
173 struct device_attribute *attr, char *buf)
174 {
175 struct aspeed_wdt *wdt = dev_get_drvdata(dev);
176 u32 status = readl(wdt->base + WDT_TIMEOUT_STATUS);
177
178 return sprintf(buf, "%u\n",
179 !(status & WDT_TIMEOUT_STATUS_BOOT_SECONDARY));
180 }
181
access_cs0_store(struct device * dev,struct device_attribute * attr,const char * buf,size_t size)182 static ssize_t access_cs0_store(struct device *dev,
183 struct device_attribute *attr, const char *buf,
184 size_t size)
185 {
186 struct aspeed_wdt *wdt = dev_get_drvdata(dev);
187 unsigned long val;
188
189 if (kstrtoul(buf, 10, &val))
190 return -EINVAL;
191
192 if (val)
193 writel(WDT_CLEAR_TIMEOUT_AND_BOOT_CODE_SELECTION,
194 wdt->base + WDT_CLEAR_TIMEOUT_STATUS);
195
196 return size;
197 }
198
199 /*
200 * This attribute exists only if the system has booted from the alternate
201 * flash with 'alt-boot' option.
202 *
203 * At alternate flash the 'access_cs0' sysfs node provides:
204 * ast2400: a way to get access to the primary SPI flash chip at CS0
205 * after booting from the alternate chip at CS1.
206 * ast2500: a way to restore the normal address mapping from
207 * (CS0->CS1, CS1->CS0) to (CS0->CS0, CS1->CS1).
208 *
209 * Clearing the boot code selection and timeout counter also resets to the
210 * initial state the chip select line mapping. When the SoC is in normal
211 * mapping state (i.e. booted from CS0), clearing those bits does nothing for
212 * both versions of the SoC. For alternate boot mode (booted from CS1 due to
213 * wdt2 expiration) the behavior differs as described above.
214 *
215 * This option can be used with wdt2 (watchdog1) only.
216 */
217 static DEVICE_ATTR_RW(access_cs0);
218
219 static struct attribute *bswitch_attrs[] = {
220 &dev_attr_access_cs0.attr,
221 NULL
222 };
223 ATTRIBUTE_GROUPS(bswitch);
224
225 static const struct watchdog_ops aspeed_wdt_ops = {
226 .start = aspeed_wdt_start,
227 .stop = aspeed_wdt_stop,
228 .ping = aspeed_wdt_ping,
229 .set_timeout = aspeed_wdt_set_timeout,
230 .restart = aspeed_wdt_restart,
231 .owner = THIS_MODULE,
232 };
233
234 static const struct watchdog_info aspeed_wdt_info = {
235 .options = WDIOF_KEEPALIVEPING
236 | WDIOF_MAGICCLOSE
237 | WDIOF_SETTIMEOUT,
238 .identity = KBUILD_MODNAME,
239 };
240
aspeed_wdt_probe(struct platform_device * pdev)241 static int aspeed_wdt_probe(struct platform_device *pdev)
242 {
243 struct device *dev = &pdev->dev;
244 const struct aspeed_wdt_config *config;
245 const struct of_device_id *ofdid;
246 struct aspeed_wdt *wdt;
247 struct device_node *np;
248 const char *reset_type;
249 u32 duration;
250 u32 status;
251 int ret;
252
253 wdt = devm_kzalloc(dev, sizeof(*wdt), GFP_KERNEL);
254 if (!wdt)
255 return -ENOMEM;
256
257 wdt->base = devm_platform_ioremap_resource(pdev, 0);
258 if (IS_ERR(wdt->base))
259 return PTR_ERR(wdt->base);
260
261 wdt->wdd.info = &aspeed_wdt_info;
262 wdt->wdd.ops = &aspeed_wdt_ops;
263 wdt->wdd.max_hw_heartbeat_ms = WDT_MAX_TIMEOUT_MS;
264 wdt->wdd.parent = dev;
265
266 wdt->wdd.timeout = WDT_DEFAULT_TIMEOUT;
267 watchdog_init_timeout(&wdt->wdd, 0, dev);
268
269 np = dev->of_node;
270
271 ofdid = of_match_node(aspeed_wdt_of_table, np);
272 if (!ofdid)
273 return -EINVAL;
274 config = ofdid->data;
275
276 /*
277 * On clock rates:
278 * - ast2400 wdt can run at PCLK, or 1MHz
279 * - ast2500 only runs at 1MHz, hard coding bit 4 to 1
280 * - ast2600 always runs at 1MHz
281 *
282 * Set the ast2400 to run at 1MHz as it simplifies the driver.
283 */
284 if (of_device_is_compatible(np, "aspeed,ast2400-wdt"))
285 wdt->ctrl = WDT_CTRL_1MHZ_CLK;
286
287 /*
288 * Control reset on a per-device basis to ensure the
289 * host is not affected by a BMC reboot
290 */
291 ret = of_property_read_string(np, "aspeed,reset-type", &reset_type);
292 if (ret) {
293 wdt->ctrl |= WDT_CTRL_RESET_MODE_SOC | WDT_CTRL_RESET_SYSTEM;
294 } else {
295 if (!strcmp(reset_type, "cpu"))
296 wdt->ctrl |= WDT_CTRL_RESET_MODE_ARM_CPU |
297 WDT_CTRL_RESET_SYSTEM;
298 else if (!strcmp(reset_type, "soc"))
299 wdt->ctrl |= WDT_CTRL_RESET_MODE_SOC |
300 WDT_CTRL_RESET_SYSTEM;
301 else if (!strcmp(reset_type, "system"))
302 wdt->ctrl |= WDT_CTRL_RESET_MODE_FULL_CHIP |
303 WDT_CTRL_RESET_SYSTEM;
304 else if (strcmp(reset_type, "none"))
305 return -EINVAL;
306 }
307 if (of_property_read_bool(np, "aspeed,external-signal"))
308 wdt->ctrl |= WDT_CTRL_WDT_EXT;
309 if (of_property_read_bool(np, "aspeed,alt-boot"))
310 wdt->ctrl |= WDT_CTRL_BOOT_SECONDARY;
311
312 if (readl(wdt->base + WDT_CTRL) & WDT_CTRL_ENABLE) {
313 /*
314 * The watchdog is running, but invoke aspeed_wdt_start() to
315 * write wdt->ctrl to WDT_CTRL to ensure the watchdog's
316 * configuration conforms to the driver's expectations.
317 * Primarily, ensure we're using the 1MHz clock source.
318 */
319 aspeed_wdt_start(&wdt->wdd);
320 set_bit(WDOG_HW_RUNNING, &wdt->wdd.status);
321 }
322
323 if ((of_device_is_compatible(np, "aspeed,ast2500-wdt")) ||
324 (of_device_is_compatible(np, "aspeed,ast2600-wdt"))) {
325 u32 reg = readl(wdt->base + WDT_RESET_WIDTH);
326
327 reg &= config->ext_pulse_width_mask;
328 if (of_property_read_bool(np, "aspeed,ext-push-pull"))
329 reg |= WDT_PUSH_PULL_MAGIC;
330 else
331 reg |= WDT_OPEN_DRAIN_MAGIC;
332
333 writel(reg, wdt->base + WDT_RESET_WIDTH);
334
335 reg &= config->ext_pulse_width_mask;
336 if (of_property_read_bool(np, "aspeed,ext-active-high"))
337 reg |= WDT_ACTIVE_HIGH_MAGIC;
338 else
339 reg |= WDT_ACTIVE_LOW_MAGIC;
340
341 writel(reg, wdt->base + WDT_RESET_WIDTH);
342 }
343
344 if (!of_property_read_u32(np, "aspeed,ext-pulse-duration", &duration)) {
345 u32 max_duration = config->ext_pulse_width_mask + 1;
346
347 if (duration == 0 || duration > max_duration) {
348 dev_err(dev, "Invalid pulse duration: %uus\n",
349 duration);
350 duration = max(1U, min(max_duration, duration));
351 dev_info(dev, "Pulse duration set to %uus\n",
352 duration);
353 }
354
355 /*
356 * The watchdog is always configured with a 1MHz source, so
357 * there is no need to scale the microsecond value. However we
358 * need to offset it - from the datasheet:
359 *
360 * "This register decides the asserting duration of wdt_ext and
361 * wdt_rstarm signal. The default value is 0xFF. It means the
362 * default asserting duration of wdt_ext and wdt_rstarm is
363 * 256us."
364 *
365 * This implies a value of 0 gives a 1us pulse.
366 */
367 writel(duration - 1, wdt->base + WDT_RESET_WIDTH);
368 }
369
370 status = readl(wdt->base + WDT_TIMEOUT_STATUS);
371 if (status & WDT_TIMEOUT_STATUS_BOOT_SECONDARY) {
372 wdt->wdd.bootstatus = WDIOF_CARDRESET;
373
374 if (of_device_is_compatible(np, "aspeed,ast2400-wdt") ||
375 of_device_is_compatible(np, "aspeed,ast2500-wdt"))
376 wdt->wdd.groups = bswitch_groups;
377 }
378
379 dev_set_drvdata(dev, wdt);
380
381 return devm_watchdog_register_device(dev, &wdt->wdd);
382 }
383
384 static struct platform_driver aspeed_watchdog_driver = {
385 .probe = aspeed_wdt_probe,
386 .driver = {
387 .name = KBUILD_MODNAME,
388 .of_match_table = of_match_ptr(aspeed_wdt_of_table),
389 },
390 };
391
aspeed_wdt_init(void)392 static int __init aspeed_wdt_init(void)
393 {
394 return platform_driver_register(&aspeed_watchdog_driver);
395 }
396 arch_initcall(aspeed_wdt_init);
397
aspeed_wdt_exit(void)398 static void __exit aspeed_wdt_exit(void)
399 {
400 platform_driver_unregister(&aspeed_watchdog_driver);
401 }
402 module_exit(aspeed_wdt_exit);
403
404 MODULE_DESCRIPTION("Aspeed Watchdog Driver");
405 MODULE_LICENSE("GPL");
406