1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3 * Watchdog driver for CSR Atlas7
4 *
5 * Copyright (c) 2015 Cambridge Silicon Radio Limited, a CSR plc group company.
6 */
7
8 #include <linux/clk.h>
9 #include <linux/io.h>
10 #include <linux/module.h>
11 #include <linux/moduleparam.h>
12 #include <linux/of.h>
13 #include <linux/platform_device.h>
14 #include <linux/watchdog.h>
15
16 #define ATLAS7_TIMER_WDT_INDEX 5
17 #define ATLAS7_WDT_DEFAULT_TIMEOUT 20
18
19 #define ATLAS7_WDT_CNT_CTRL (0 + 4 * ATLAS7_TIMER_WDT_INDEX)
20 #define ATLAS7_WDT_CNT_MATCH (0x18 + 4 * ATLAS7_TIMER_WDT_INDEX)
21 #define ATLAS7_WDT_CNT (0x48 + 4 * ATLAS7_TIMER_WDT_INDEX)
22 #define ATLAS7_WDT_CNT_EN (BIT(0) | BIT(1))
23 #define ATLAS7_WDT_EN 0x64
24
25 static unsigned int timeout = ATLAS7_WDT_DEFAULT_TIMEOUT;
26 static bool nowayout = WATCHDOG_NOWAYOUT;
27
28 module_param(timeout, uint, 0);
29 module_param(nowayout, bool, 0);
30
31 MODULE_PARM_DESC(timeout, "Default watchdog timeout (in seconds)");
32 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="
33 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
34
35 struct atlas7_wdog {
36 struct device *dev;
37 void __iomem *base;
38 unsigned long tick_rate;
39 struct clk *clk;
40 };
41
atlas7_wdt_gettimeleft(struct watchdog_device * wdd)42 static unsigned int atlas7_wdt_gettimeleft(struct watchdog_device *wdd)
43 {
44 struct atlas7_wdog *wdt = watchdog_get_drvdata(wdd);
45 u32 counter, match, delta;
46
47 counter = readl(wdt->base + ATLAS7_WDT_CNT);
48 match = readl(wdt->base + ATLAS7_WDT_CNT_MATCH);
49 delta = match - counter;
50
51 return delta / wdt->tick_rate;
52 }
53
atlas7_wdt_ping(struct watchdog_device * wdd)54 static int atlas7_wdt_ping(struct watchdog_device *wdd)
55 {
56 struct atlas7_wdog *wdt = watchdog_get_drvdata(wdd);
57 u32 counter, match, delta;
58
59 counter = readl(wdt->base + ATLAS7_WDT_CNT);
60 delta = wdd->timeout * wdt->tick_rate;
61 match = counter + delta;
62
63 writel(match, wdt->base + ATLAS7_WDT_CNT_MATCH);
64
65 return 0;
66 }
67
atlas7_wdt_enable(struct watchdog_device * wdd)68 static int atlas7_wdt_enable(struct watchdog_device *wdd)
69 {
70 struct atlas7_wdog *wdt = watchdog_get_drvdata(wdd);
71
72 atlas7_wdt_ping(wdd);
73
74 writel(readl(wdt->base + ATLAS7_WDT_CNT_CTRL) | ATLAS7_WDT_CNT_EN,
75 wdt->base + ATLAS7_WDT_CNT_CTRL);
76 writel(1, wdt->base + ATLAS7_WDT_EN);
77
78 return 0;
79 }
80
atlas7_wdt_disable(struct watchdog_device * wdd)81 static int atlas7_wdt_disable(struct watchdog_device *wdd)
82 {
83 struct atlas7_wdog *wdt = watchdog_get_drvdata(wdd);
84
85 writel(0, wdt->base + ATLAS7_WDT_EN);
86 writel(readl(wdt->base + ATLAS7_WDT_CNT_CTRL) & ~ATLAS7_WDT_CNT_EN,
87 wdt->base + ATLAS7_WDT_CNT_CTRL);
88
89 return 0;
90 }
91
atlas7_wdt_settimeout(struct watchdog_device * wdd,unsigned int to)92 static int atlas7_wdt_settimeout(struct watchdog_device *wdd, unsigned int to)
93 {
94 wdd->timeout = to;
95
96 return 0;
97 }
98
99 #define OPTIONS (WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE)
100
101 static const struct watchdog_info atlas7_wdt_ident = {
102 .options = OPTIONS,
103 .firmware_version = 0,
104 .identity = "atlas7 Watchdog",
105 };
106
107 static const struct watchdog_ops atlas7_wdt_ops = {
108 .owner = THIS_MODULE,
109 .start = atlas7_wdt_enable,
110 .stop = atlas7_wdt_disable,
111 .get_timeleft = atlas7_wdt_gettimeleft,
112 .ping = atlas7_wdt_ping,
113 .set_timeout = atlas7_wdt_settimeout,
114 };
115
116 static struct watchdog_device atlas7_wdd = {
117 .info = &atlas7_wdt_ident,
118 .ops = &atlas7_wdt_ops,
119 .timeout = ATLAS7_WDT_DEFAULT_TIMEOUT,
120 };
121
122 static const struct of_device_id atlas7_wdt_ids[] = {
123 { .compatible = "sirf,atlas7-tick"},
124 {}
125 };
126
atlas7_clk_disable_unprepare(void * data)127 static void atlas7_clk_disable_unprepare(void *data)
128 {
129 clk_disable_unprepare(data);
130 }
131
atlas7_wdt_probe(struct platform_device * pdev)132 static int atlas7_wdt_probe(struct platform_device *pdev)
133 {
134 struct device *dev = &pdev->dev;
135 struct atlas7_wdog *wdt;
136 struct clk *clk;
137 int ret;
138
139 wdt = devm_kzalloc(dev, sizeof(*wdt), GFP_KERNEL);
140 if (!wdt)
141 return -ENOMEM;
142 wdt->base = devm_platform_ioremap_resource(pdev, 0);
143 if (IS_ERR(wdt->base))
144 return PTR_ERR(wdt->base);
145
146 clk = devm_clk_get(dev, NULL);
147 if (IS_ERR(clk))
148 return PTR_ERR(clk);
149 ret = clk_prepare_enable(clk);
150 if (ret) {
151 dev_err(dev, "clk enable failed\n");
152 return ret;
153 }
154 ret = devm_add_action_or_reset(dev, atlas7_clk_disable_unprepare, clk);
155 if (ret)
156 return ret;
157
158 /* disable watchdog hardware */
159 writel(0, wdt->base + ATLAS7_WDT_CNT_CTRL);
160
161 wdt->tick_rate = clk_get_rate(clk);
162 if (!wdt->tick_rate)
163 return -EINVAL;
164
165 wdt->clk = clk;
166 atlas7_wdd.min_timeout = 1;
167 atlas7_wdd.max_timeout = UINT_MAX / wdt->tick_rate;
168
169 watchdog_init_timeout(&atlas7_wdd, 0, dev);
170 watchdog_set_nowayout(&atlas7_wdd, nowayout);
171
172 watchdog_set_drvdata(&atlas7_wdd, wdt);
173 platform_set_drvdata(pdev, &atlas7_wdd);
174
175 watchdog_stop_on_reboot(&atlas7_wdd);
176 watchdog_stop_on_unregister(&atlas7_wdd);
177 return devm_watchdog_register_device(dev, &atlas7_wdd);
178 }
179
atlas7_wdt_suspend(struct device * dev)180 static int __maybe_unused atlas7_wdt_suspend(struct device *dev)
181 {
182 /*
183 * NOTE:timer controller registers settings are saved
184 * and restored back by the timer-atlas7.c
185 */
186 return 0;
187 }
188
atlas7_wdt_resume(struct device * dev)189 static int __maybe_unused atlas7_wdt_resume(struct device *dev)
190 {
191 struct watchdog_device *wdd = dev_get_drvdata(dev);
192
193 /*
194 * NOTE: Since timer controller registers settings are saved
195 * and restored back by the timer-atlas7.c, so we need not
196 * update WD settings except refreshing timeout.
197 */
198 atlas7_wdt_ping(wdd);
199
200 return 0;
201 }
202
203 static SIMPLE_DEV_PM_OPS(atlas7_wdt_pm_ops,
204 atlas7_wdt_suspend, atlas7_wdt_resume);
205
206 MODULE_DEVICE_TABLE(of, atlas7_wdt_ids);
207
208 static struct platform_driver atlas7_wdt_driver = {
209 .driver = {
210 .name = "atlas7-wdt",
211 .pm = &atlas7_wdt_pm_ops,
212 .of_match_table = atlas7_wdt_ids,
213 },
214 .probe = atlas7_wdt_probe,
215 };
216 module_platform_driver(atlas7_wdt_driver);
217
218 MODULE_DESCRIPTION("CSRatlas7 watchdog driver");
219 MODULE_AUTHOR("Guo Zeng <Guo.Zeng@csr.com>");
220 MODULE_LICENSE("GPL v2");
221 MODULE_ALIAS("platform:atlas7-wdt");
222