virtio-mem: simplify high-level unplug handling in Sub Block Mode
[linux-2.6-microblaze.git] / drivers / watchdog / bcm7038_wdt.c
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/pm.h>
14 #include <linux/watchdog.h>
15
16 #define WDT_START_1             0xff00
17 #define WDT_START_2             0x00ff
18 #define WDT_STOP_1              0xee00
19 #define WDT_STOP_2              0x00ee
20
21 #define WDT_TIMEOUT_REG         0x0
22 #define WDT_CMD_REG             0x4
23
24 #define WDT_MIN_TIMEOUT         1 /* seconds */
25 #define WDT_DEFAULT_TIMEOUT     30 /* seconds */
26 #define WDT_DEFAULT_RATE        27000000
27
28 struct bcm7038_watchdog {
29         void __iomem            *base;
30         struct watchdog_device  wdd;
31         u32                     rate;
32         struct clk              *clk;
33 };
34
35 static bool nowayout = WATCHDOG_NOWAYOUT;
36
37 static void bcm7038_wdt_set_timeout_reg(struct watchdog_device *wdog)
38 {
39         struct bcm7038_watchdog *wdt = watchdog_get_drvdata(wdog);
40         u32 timeout;
41
42         timeout = wdt->rate * wdog->timeout;
43
44         writel(timeout, wdt->base + WDT_TIMEOUT_REG);
45 }
46
47 static int bcm7038_wdt_ping(struct watchdog_device *wdog)
48 {
49         struct bcm7038_watchdog *wdt = watchdog_get_drvdata(wdog);
50
51         writel(WDT_START_1, wdt->base + WDT_CMD_REG);
52         writel(WDT_START_2, wdt->base + WDT_CMD_REG);
53
54         return 0;
55 }
56
57 static int bcm7038_wdt_start(struct watchdog_device *wdog)
58 {
59         bcm7038_wdt_set_timeout_reg(wdog);
60         bcm7038_wdt_ping(wdog);
61
62         return 0;
63 }
64
65 static int bcm7038_wdt_stop(struct watchdog_device *wdog)
66 {
67         struct bcm7038_watchdog *wdt = watchdog_get_drvdata(wdog);
68
69         writel(WDT_STOP_1, wdt->base + WDT_CMD_REG);
70         writel(WDT_STOP_2, wdt->base + WDT_CMD_REG);
71
72         return 0;
73 }
74
75 static int bcm7038_wdt_set_timeout(struct watchdog_device *wdog,
76                                    unsigned int t)
77 {
78         /* Can't modify timeout value if watchdog timer is running */
79         bcm7038_wdt_stop(wdog);
80         wdog->timeout = t;
81         bcm7038_wdt_start(wdog);
82
83         return 0;
84 }
85
86 static unsigned int bcm7038_wdt_get_timeleft(struct watchdog_device *wdog)
87 {
88         struct bcm7038_watchdog *wdt = watchdog_get_drvdata(wdog);
89         u32 time_left;
90
91         time_left = readl(wdt->base + WDT_CMD_REG);
92
93         return time_left / wdt->rate;
94 }
95
96 static const struct watchdog_info bcm7038_wdt_info = {
97         .identity       = "Broadcom BCM7038 Watchdog Timer",
98         .options        = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING |
99                                 WDIOF_MAGICCLOSE
100 };
101
102 static const struct watchdog_ops bcm7038_wdt_ops = {
103         .owner          = THIS_MODULE,
104         .start          = bcm7038_wdt_start,
105         .stop           = bcm7038_wdt_stop,
106         .set_timeout    = bcm7038_wdt_set_timeout,
107         .get_timeleft   = bcm7038_wdt_get_timeleft,
108 };
109
110 static void bcm7038_clk_disable_unprepare(void *data)
111 {
112         clk_disable_unprepare(data);
113 }
114
115 static int bcm7038_wdt_probe(struct platform_device *pdev)
116 {
117         struct device *dev = &pdev->dev;
118         struct bcm7038_watchdog *wdt;
119         int err;
120
121         wdt = devm_kzalloc(dev, sizeof(*wdt), GFP_KERNEL);
122         if (!wdt)
123                 return -ENOMEM;
124
125         platform_set_drvdata(pdev, wdt);
126
127         wdt->base = devm_platform_ioremap_resource(pdev, 0);
128         if (IS_ERR(wdt->base))
129                 return PTR_ERR(wdt->base);
130
131         wdt->clk = devm_clk_get(dev, NULL);
132         /* If unable to get clock, use default frequency */
133         if (!IS_ERR(wdt->clk)) {
134                 err = clk_prepare_enable(wdt->clk);
135                 if (err)
136                         return err;
137                 err = devm_add_action_or_reset(dev,
138                                                bcm7038_clk_disable_unprepare,
139                                                wdt->clk);
140                 if (err)
141                         return err;
142                 wdt->rate = clk_get_rate(wdt->clk);
143                 /* Prevent divide-by-zero exception */
144                 if (!wdt->rate)
145                         wdt->rate = WDT_DEFAULT_RATE;
146         } else {
147                 wdt->rate = WDT_DEFAULT_RATE;
148                 wdt->clk = NULL;
149         }
150
151         wdt->wdd.info           = &bcm7038_wdt_info;
152         wdt->wdd.ops            = &bcm7038_wdt_ops;
153         wdt->wdd.min_timeout    = WDT_MIN_TIMEOUT;
154         wdt->wdd.timeout        = WDT_DEFAULT_TIMEOUT;
155         wdt->wdd.max_timeout    = 0xffffffff / wdt->rate;
156         wdt->wdd.parent         = dev;
157         watchdog_set_drvdata(&wdt->wdd, wdt);
158
159         watchdog_stop_on_reboot(&wdt->wdd);
160         watchdog_stop_on_unregister(&wdt->wdd);
161         err = devm_watchdog_register_device(dev, &wdt->wdd);
162         if (err)
163                 return err;
164
165         dev_info(dev, "Registered BCM7038 Watchdog\n");
166
167         return 0;
168 }
169
170 #ifdef CONFIG_PM_SLEEP
171 static int bcm7038_wdt_suspend(struct device *dev)
172 {
173         struct bcm7038_watchdog *wdt = dev_get_drvdata(dev);
174
175         if (watchdog_active(&wdt->wdd))
176                 return bcm7038_wdt_stop(&wdt->wdd);
177
178         return 0;
179 }
180
181 static int bcm7038_wdt_resume(struct device *dev)
182 {
183         struct bcm7038_watchdog *wdt = dev_get_drvdata(dev);
184
185         if (watchdog_active(&wdt->wdd))
186                 return bcm7038_wdt_start(&wdt->wdd);
187
188         return 0;
189 }
190 #endif
191
192 static SIMPLE_DEV_PM_OPS(bcm7038_wdt_pm_ops, bcm7038_wdt_suspend,
193                          bcm7038_wdt_resume);
194
195 static const struct of_device_id bcm7038_wdt_match[] = {
196         { .compatible = "brcm,bcm7038-wdt" },
197         {},
198 };
199 MODULE_DEVICE_TABLE(of, bcm7038_wdt_match);
200
201 static struct platform_driver bcm7038_wdt_driver = {
202         .probe          = bcm7038_wdt_probe,
203         .driver         = {
204                 .name           = "bcm7038-wdt",
205                 .of_match_table = bcm7038_wdt_match,
206                 .pm             = &bcm7038_wdt_pm_ops,
207         }
208 };
209 module_platform_driver(bcm7038_wdt_driver);
210
211 module_param(nowayout, bool, 0);
212 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="
213         __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
214 MODULE_LICENSE("GPL");
215 MODULE_DESCRIPTION("Driver for Broadcom 7038 SoCs Watchdog");
216 MODULE_AUTHOR("Justin Chen");