1 // SPDX-License-Identifier: GPL-2.0+
2 /*
3 * Copyright (C) 2015 Broadcom Corporation
4 *
5 */
6
7 #include <linux/clk.h>
8 #include <linux/init.h>
9 #include <linux/io.h>
10 #include <linux/module.h>
11 #include <linux/of.h>
12 #include <linux/platform_device.h>
13 #include <linux/platform_data/bcm7038_wdt.h>
14 #include <linux/pm.h>
15 #include <linux/watchdog.h>
16
17 #define WDT_START_1 0xff00
18 #define WDT_START_2 0x00ff
19 #define WDT_STOP_1 0xee00
20 #define WDT_STOP_2 0x00ee
21
22 #define WDT_TIMEOUT_REG 0x0
23 #define WDT_CMD_REG 0x4
24
25 #define WDT_MIN_TIMEOUT 1 /* seconds */
26 #define WDT_DEFAULT_TIMEOUT 30 /* seconds */
27 #define WDT_DEFAULT_RATE 27000000
28
29 struct bcm7038_watchdog {
30 void __iomem *base;
31 struct watchdog_device wdd;
32 u32 rate;
33 struct clk *clk;
34 };
35
36 static bool nowayout = WATCHDOG_NOWAYOUT;
37
bcm7038_wdt_write(u32 value,void __iomem * addr)38 static inline void bcm7038_wdt_write(u32 value, void __iomem *addr)
39 {
40 /* MIPS chips strapped for BE will automagically configure the
41 * peripheral registers for CPU-native byte order.
42 */
43 if (IS_ENABLED(CONFIG_MIPS) && IS_ENABLED(CONFIG_CPU_BIG_ENDIAN))
44 __raw_writel(value, addr);
45 else
46 writel_relaxed(value, addr);
47 }
48
bcm7038_wdt_read(void __iomem * addr)49 static inline u32 bcm7038_wdt_read(void __iomem *addr)
50 {
51 if (IS_ENABLED(CONFIG_MIPS) && IS_ENABLED(CONFIG_CPU_BIG_ENDIAN))
52 return __raw_readl(addr);
53 else
54 return readl_relaxed(addr);
55 }
56
bcm7038_wdt_set_timeout_reg(struct watchdog_device * wdog)57 static void bcm7038_wdt_set_timeout_reg(struct watchdog_device *wdog)
58 {
59 struct bcm7038_watchdog *wdt = watchdog_get_drvdata(wdog);
60 u32 timeout;
61
62 timeout = wdt->rate * wdog->timeout;
63
64 bcm7038_wdt_write(timeout, wdt->base + WDT_TIMEOUT_REG);
65 }
66
bcm7038_wdt_ping(struct watchdog_device * wdog)67 static int bcm7038_wdt_ping(struct watchdog_device *wdog)
68 {
69 struct bcm7038_watchdog *wdt = watchdog_get_drvdata(wdog);
70
71 bcm7038_wdt_write(WDT_START_1, wdt->base + WDT_CMD_REG);
72 bcm7038_wdt_write(WDT_START_2, wdt->base + WDT_CMD_REG);
73
74 return 0;
75 }
76
bcm7038_wdt_start(struct watchdog_device * wdog)77 static int bcm7038_wdt_start(struct watchdog_device *wdog)
78 {
79 bcm7038_wdt_set_timeout_reg(wdog);
80 bcm7038_wdt_ping(wdog);
81
82 return 0;
83 }
84
bcm7038_wdt_stop(struct watchdog_device * wdog)85 static int bcm7038_wdt_stop(struct watchdog_device *wdog)
86 {
87 struct bcm7038_watchdog *wdt = watchdog_get_drvdata(wdog);
88
89 bcm7038_wdt_write(WDT_STOP_1, wdt->base + WDT_CMD_REG);
90 bcm7038_wdt_write(WDT_STOP_2, wdt->base + WDT_CMD_REG);
91
92 return 0;
93 }
94
bcm7038_wdt_set_timeout(struct watchdog_device * wdog,unsigned int t)95 static int bcm7038_wdt_set_timeout(struct watchdog_device *wdog,
96 unsigned int t)
97 {
98 /* Can't modify timeout value if watchdog timer is running */
99 bcm7038_wdt_stop(wdog);
100 wdog->timeout = t;
101 bcm7038_wdt_start(wdog);
102
103 return 0;
104 }
105
bcm7038_wdt_get_timeleft(struct watchdog_device * wdog)106 static unsigned int bcm7038_wdt_get_timeleft(struct watchdog_device *wdog)
107 {
108 struct bcm7038_watchdog *wdt = watchdog_get_drvdata(wdog);
109 u32 time_left;
110
111 time_left = bcm7038_wdt_read(wdt->base + WDT_CMD_REG);
112
113 return time_left / wdt->rate;
114 }
115
116 static const struct watchdog_info bcm7038_wdt_info = {
117 .identity = "Broadcom BCM7038 Watchdog Timer",
118 .options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING |
119 WDIOF_MAGICCLOSE
120 };
121
122 static const struct watchdog_ops bcm7038_wdt_ops = {
123 .owner = THIS_MODULE,
124 .start = bcm7038_wdt_start,
125 .stop = bcm7038_wdt_stop,
126 .set_timeout = bcm7038_wdt_set_timeout,
127 .get_timeleft = bcm7038_wdt_get_timeleft,
128 };
129
bcm7038_clk_disable_unprepare(void * data)130 static void bcm7038_clk_disable_unprepare(void *data)
131 {
132 clk_disable_unprepare(data);
133 }
134
bcm7038_wdt_probe(struct platform_device * pdev)135 static int bcm7038_wdt_probe(struct platform_device *pdev)
136 {
137 struct bcm7038_wdt_platform_data *pdata = pdev->dev.platform_data;
138 struct device *dev = &pdev->dev;
139 struct bcm7038_watchdog *wdt;
140 const char *clk_name = NULL;
141 int err;
142
143 wdt = devm_kzalloc(dev, sizeof(*wdt), GFP_KERNEL);
144 if (!wdt)
145 return -ENOMEM;
146
147 platform_set_drvdata(pdev, wdt);
148
149 wdt->base = devm_platform_ioremap_resource(pdev, 0);
150 if (IS_ERR(wdt->base))
151 return PTR_ERR(wdt->base);
152
153 if (pdata && pdata->clk_name)
154 clk_name = pdata->clk_name;
155
156 wdt->clk = devm_clk_get(dev, clk_name);
157 /* If unable to get clock, use default frequency */
158 if (!IS_ERR(wdt->clk)) {
159 err = clk_prepare_enable(wdt->clk);
160 if (err)
161 return err;
162 err = devm_add_action_or_reset(dev,
163 bcm7038_clk_disable_unprepare,
164 wdt->clk);
165 if (err)
166 return err;
167 wdt->rate = clk_get_rate(wdt->clk);
168 /* Prevent divide-by-zero exception */
169 if (!wdt->rate)
170 wdt->rate = WDT_DEFAULT_RATE;
171 } else {
172 wdt->rate = WDT_DEFAULT_RATE;
173 wdt->clk = NULL;
174 }
175
176 wdt->wdd.info = &bcm7038_wdt_info;
177 wdt->wdd.ops = &bcm7038_wdt_ops;
178 wdt->wdd.min_timeout = WDT_MIN_TIMEOUT;
179 wdt->wdd.timeout = WDT_DEFAULT_TIMEOUT;
180 wdt->wdd.max_timeout = 0xffffffff / wdt->rate;
181 wdt->wdd.parent = dev;
182 watchdog_set_drvdata(&wdt->wdd, wdt);
183
184 watchdog_stop_on_reboot(&wdt->wdd);
185 watchdog_stop_on_unregister(&wdt->wdd);
186 err = devm_watchdog_register_device(dev, &wdt->wdd);
187 if (err)
188 return err;
189
190 dev_info(dev, "Registered BCM7038 Watchdog\n");
191
192 return 0;
193 }
194
bcm7038_wdt_suspend(struct device * dev)195 static int bcm7038_wdt_suspend(struct device *dev)
196 {
197 struct bcm7038_watchdog *wdt = dev_get_drvdata(dev);
198
199 if (watchdog_active(&wdt->wdd))
200 return bcm7038_wdt_stop(&wdt->wdd);
201
202 return 0;
203 }
204
bcm7038_wdt_resume(struct device * dev)205 static int bcm7038_wdt_resume(struct device *dev)
206 {
207 struct bcm7038_watchdog *wdt = dev_get_drvdata(dev);
208
209 if (watchdog_active(&wdt->wdd))
210 return bcm7038_wdt_start(&wdt->wdd);
211
212 return 0;
213 }
214
215 static DEFINE_SIMPLE_DEV_PM_OPS(bcm7038_wdt_pm_ops,
216 bcm7038_wdt_suspend, bcm7038_wdt_resume);
217
218 static const struct of_device_id bcm7038_wdt_match[] = {
219 { .compatible = "brcm,bcm6345-wdt" },
220 { .compatible = "brcm,bcm7038-wdt" },
221 {},
222 };
223 MODULE_DEVICE_TABLE(of, bcm7038_wdt_match);
224
225 static const struct platform_device_id bcm7038_wdt_devtype[] = {
226 { .name = "bcm63xx-wdt" },
227 { /* sentinel */ },
228 };
229 MODULE_DEVICE_TABLE(platform, bcm7038_wdt_devtype);
230
231 static struct platform_driver bcm7038_wdt_driver = {
232 .probe = bcm7038_wdt_probe,
233 .id_table = bcm7038_wdt_devtype,
234 .driver = {
235 .name = "bcm7038-wdt",
236 .of_match_table = bcm7038_wdt_match,
237 .pm = pm_sleep_ptr(&bcm7038_wdt_pm_ops),
238 }
239 };
240 module_platform_driver(bcm7038_wdt_driver);
241
242 module_param(nowayout, bool, 0);
243 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="
244 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
245 MODULE_LICENSE("GPL");
246 MODULE_DESCRIPTION("Driver for Broadcom 7038 SoCs Watchdog");
247 MODULE_AUTHOR("Justin Chen");
248