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6adb730d MM |
1 | /* |
2 | * Copyright (C) 2013 Broadcom Corporation | |
3 | * | |
4 | * This program is free software; you can redistribute it and/or | |
5 | * modify it under the terms of the GNU General Public License as | |
6 | * published by the Free Software Foundation version 2. | |
7 | * | |
8 | * This program is distributed "as is" WITHOUT ANY WARRANTY of any | |
9 | * kind, whether express or implied; without even the implied warranty | |
10 | * of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
11 | * GNU General Public License for more details. | |
12 | */ | |
13 | ||
14 | #include <linux/delay.h> | |
15 | #include <linux/err.h> | |
16 | #include <linux/io.h> | |
17 | #include <linux/module.h> | |
18 | #include <linux/of_address.h> | |
19 | #include <linux/platform_device.h> | |
20 | #include <linux/watchdog.h> | |
21 | ||
22 | #define SECWDOG_CTRL_REG 0x00000000 | |
23 | #define SECWDOG_COUNT_REG 0x00000004 | |
24 | ||
25 | #define SECWDOG_RESERVED_MASK 0x1dffffff | |
26 | #define SECWDOG_WD_LOAD_FLAG 0x10000000 | |
27 | #define SECWDOG_EN_MASK 0x08000000 | |
28 | #define SECWDOG_SRSTEN_MASK 0x04000000 | |
29 | #define SECWDOG_RES_MASK 0x00f00000 | |
30 | #define SECWDOG_COUNT_MASK 0x000fffff | |
31 | ||
32 | #define SECWDOG_MAX_COUNT SECWDOG_COUNT_MASK | |
33 | #define SECWDOG_CLKS_SHIFT 20 | |
34 | #define SECWDOG_MAX_RES 15 | |
35 | #define SECWDOG_DEFAULT_RESOLUTION 4 | |
36 | #define SECWDOG_MAX_TRY 1000 | |
37 | ||
38 | #define SECS_TO_TICKS(x, w) ((x) << (w)->resolution) | |
39 | #define TICKS_TO_SECS(x, w) ((x) >> (w)->resolution) | |
40 | ||
41 | #define BCM_KONA_WDT_NAME "bcm_kona_wdt" | |
42 | ||
43 | struct bcm_kona_wdt { | |
44 | void __iomem *base; | |
45 | /* | |
46 | * One watchdog tick is 1/(2^resolution) seconds. Resolution can take | |
47 | * the values 0-15, meaning one tick can be 1s to 30.52us. Our default | |
48 | * resolution of 4 means one tick is 62.5ms. | |
49 | * | |
50 | * The watchdog counter is 20 bits. Depending on resolution, the maximum | |
51 | * counter value of 0xfffff expires after about 12 days (resolution 0) | |
52 | * down to only 32s (resolution 15). The default resolution of 4 gives | |
53 | * us a maximum of about 18 hours and 12 minutes before the watchdog | |
54 | * times out. | |
55 | */ | |
56 | int resolution; | |
57 | spinlock_t lock; | |
58 | }; | |
59 | ||
60 | static int secure_register_read(void __iomem *addr) | |
61 | { | |
62 | uint32_t val; | |
63 | unsigned count = 0; | |
64 | ||
65 | /* | |
66 | * If the WD_LOAD_FLAG is set, the watchdog counter field is being | |
67 | * updated in hardware. Once the WD timer is updated in hardware, it | |
68 | * gets cleared. | |
69 | */ | |
70 | do { | |
71 | if (unlikely(count > 1)) | |
72 | udelay(5); | |
73 | val = readl_relaxed(addr); | |
74 | count++; | |
75 | } while ((val & SECWDOG_WD_LOAD_FLAG) && count < SECWDOG_MAX_TRY); | |
76 | ||
77 | /* This is the only place we return a negative value. */ | |
78 | if (val & SECWDOG_WD_LOAD_FLAG) | |
79 | return -ETIMEDOUT; | |
80 | ||
81 | /* We always mask out reserved bits. */ | |
82 | val &= SECWDOG_RESERVED_MASK; | |
83 | ||
84 | return val; | |
85 | } | |
86 | ||
87 | static int bcm_kona_wdt_ctrl_reg_modify(struct bcm_kona_wdt *wdt, | |
88 | unsigned mask, unsigned newval) | |
89 | { | |
90 | int val; | |
91 | unsigned long flags; | |
92 | int ret = 0; | |
93 | ||
94 | spin_lock_irqsave(&wdt->lock, flags); | |
95 | ||
96 | val = secure_register_read(wdt->base + SECWDOG_CTRL_REG); | |
97 | if (val < 0) { | |
98 | ret = val; | |
99 | } else { | |
100 | val &= ~mask; | |
101 | val |= newval; | |
102 | writel_relaxed(val, wdt->base + SECWDOG_CTRL_REG); | |
103 | } | |
104 | ||
105 | spin_unlock_irqrestore(&wdt->lock, flags); | |
106 | ||
107 | return ret; | |
108 | } | |
109 | ||
110 | static int bcm_kona_wdt_set_resolution_reg(struct bcm_kona_wdt *wdt) | |
111 | { | |
112 | if (wdt->resolution > SECWDOG_MAX_RES) | |
113 | return -EINVAL; | |
114 | ||
115 | return bcm_kona_wdt_ctrl_reg_modify(wdt, SECWDOG_RES_MASK, | |
116 | wdt->resolution << SECWDOG_CLKS_SHIFT); | |
117 | } | |
118 | ||
119 | static int bcm_kona_wdt_set_timeout_reg(struct watchdog_device *wdog, | |
120 | unsigned watchdog_flags) | |
121 | { | |
122 | struct bcm_kona_wdt *wdt = watchdog_get_drvdata(wdog); | |
123 | ||
124 | return bcm_kona_wdt_ctrl_reg_modify(wdt, SECWDOG_COUNT_MASK, | |
125 | SECS_TO_TICKS(wdog->timeout, wdt) | | |
126 | watchdog_flags); | |
127 | } | |
128 | ||
129 | static int bcm_kona_wdt_set_timeout(struct watchdog_device *wdog, | |
130 | unsigned int t) | |
131 | { | |
132 | wdog->timeout = t; | |
133 | return 0; | |
134 | } | |
135 | ||
136 | static unsigned int bcm_kona_wdt_get_timeleft(struct watchdog_device *wdog) | |
137 | { | |
138 | struct bcm_kona_wdt *wdt = watchdog_get_drvdata(wdog); | |
139 | int val; | |
140 | unsigned long flags; | |
141 | ||
142 | spin_lock_irqsave(&wdt->lock, flags); | |
143 | val = secure_register_read(wdt->base + SECWDOG_COUNT_REG); | |
144 | spin_unlock_irqrestore(&wdt->lock, flags); | |
145 | ||
146 | if (val < 0) | |
147 | return val; | |
148 | ||
149 | return TICKS_TO_SECS(val & SECWDOG_COUNT_MASK, wdt); | |
150 | } | |
151 | ||
152 | static int bcm_kona_wdt_start(struct watchdog_device *wdog) | |
153 | { | |
154 | return bcm_kona_wdt_set_timeout_reg(wdog, | |
155 | SECWDOG_EN_MASK | SECWDOG_SRSTEN_MASK); | |
156 | } | |
157 | ||
158 | static int bcm_kona_wdt_stop(struct watchdog_device *wdog) | |
159 | { | |
160 | struct bcm_kona_wdt *wdt = watchdog_get_drvdata(wdog); | |
161 | ||
162 | return bcm_kona_wdt_ctrl_reg_modify(wdt, SECWDOG_EN_MASK | | |
163 | SECWDOG_SRSTEN_MASK, 0); | |
164 | } | |
165 | ||
166 | static struct watchdog_ops bcm_kona_wdt_ops = { | |
167 | .owner = THIS_MODULE, | |
168 | .start = bcm_kona_wdt_start, | |
169 | .stop = bcm_kona_wdt_stop, | |
170 | .set_timeout = bcm_kona_wdt_set_timeout, | |
171 | .get_timeleft = bcm_kona_wdt_get_timeleft, | |
172 | }; | |
173 | ||
174 | static struct watchdog_info bcm_kona_wdt_info = { | |
175 | .options = WDIOF_SETTIMEOUT | WDIOF_MAGICCLOSE | | |
176 | WDIOF_KEEPALIVEPING, | |
177 | .identity = "Broadcom Kona Watchdog Timer", | |
178 | }; | |
179 | ||
180 | static struct watchdog_device bcm_kona_wdt_wdd = { | |
181 | .info = &bcm_kona_wdt_info, | |
182 | .ops = &bcm_kona_wdt_ops, | |
183 | .min_timeout = 1, | |
184 | .max_timeout = SECWDOG_MAX_COUNT >> SECWDOG_DEFAULT_RESOLUTION, | |
185 | .timeout = SECWDOG_MAX_COUNT >> SECWDOG_DEFAULT_RESOLUTION, | |
186 | }; | |
187 | ||
188 | static void bcm_kona_wdt_shutdown(struct platform_device *pdev) | |
189 | { | |
190 | bcm_kona_wdt_stop(&bcm_kona_wdt_wdd); | |
191 | } | |
192 | ||
193 | static int bcm_kona_wdt_probe(struct platform_device *pdev) | |
194 | { | |
195 | struct device *dev = &pdev->dev; | |
196 | struct bcm_kona_wdt *wdt; | |
197 | struct resource *res; | |
198 | int ret; | |
199 | ||
200 | wdt = devm_kzalloc(dev, sizeof(*wdt), GFP_KERNEL); | |
201 | if (!wdt) | |
202 | return -ENOMEM; | |
203 | ||
204 | res = platform_get_resource(pdev, IORESOURCE_MEM, 0); | |
205 | wdt->base = devm_ioremap_resource(dev, res); | |
206 | if (IS_ERR(wdt->base)) | |
207 | return -ENODEV; | |
208 | ||
209 | wdt->resolution = SECWDOG_DEFAULT_RESOLUTION; | |
210 | ret = bcm_kona_wdt_set_resolution_reg(wdt); | |
211 | if (ret) { | |
212 | dev_err(dev, "Failed to set resolution (error: %d)", ret); | |
213 | return ret; | |
214 | } | |
215 | ||
216 | spin_lock_init(&wdt->lock); | |
217 | platform_set_drvdata(pdev, wdt); | |
218 | watchdog_set_drvdata(&bcm_kona_wdt_wdd, wdt); | |
219 | ||
220 | ret = bcm_kona_wdt_set_timeout_reg(&bcm_kona_wdt_wdd, 0); | |
221 | if (ret) { | |
222 | dev_err(dev, "Failed set watchdog timeout"); | |
223 | return ret; | |
224 | } | |
225 | ||
226 | ret = watchdog_register_device(&bcm_kona_wdt_wdd); | |
227 | if (ret) { | |
228 | dev_err(dev, "Failed to register watchdog device"); | |
229 | return ret; | |
230 | } | |
231 | ||
232 | dev_dbg(dev, "Broadcom Kona Watchdog Timer"); | |
233 | ||
234 | return 0; | |
235 | } | |
236 | ||
237 | static int bcm_kona_wdt_remove(struct platform_device *pdev) | |
238 | { | |
239 | bcm_kona_wdt_shutdown(pdev); | |
240 | watchdog_unregister_device(&bcm_kona_wdt_wdd); | |
241 | dev_dbg(&pdev->dev, "Watchdog driver disabled"); | |
242 | ||
243 | return 0; | |
244 | } | |
245 | ||
246 | static const struct of_device_id bcm_kona_wdt_of_match[] = { | |
247 | { .compatible = "brcm,kona-wdt", }, | |
248 | {}, | |
249 | }; | |
250 | MODULE_DEVICE_TABLE(of, bcm_kona_wdt_of_match); | |
251 | ||
252 | static struct platform_driver bcm_kona_wdt_driver = { | |
253 | .driver = { | |
254 | .name = BCM_KONA_WDT_NAME, | |
255 | .owner = THIS_MODULE, | |
256 | .of_match_table = bcm_kona_wdt_of_match, | |
257 | }, | |
258 | .probe = bcm_kona_wdt_probe, | |
259 | .remove = bcm_kona_wdt_remove, | |
260 | .shutdown = bcm_kona_wdt_shutdown, | |
261 | }; | |
262 | ||
263 | module_platform_driver(bcm_kona_wdt_driver); | |
264 | ||
265 | MODULE_ALIAS("platform:" BCM_KONA_WDT_NAME); | |
266 | MODULE_AUTHOR("Markus Mayer <mmayer@broadcom.com>"); | |
267 | MODULE_DESCRIPTION("Broadcom Kona Watchdog Driver"); | |
268 | MODULE_LICENSE("GPL v2"); |