1 // SPDX-License-Identifier: GPL-2.0+
2 /*
3 * Copyright (C) 2015 Mans Rullgard <mans@mansr.com>
4 * SMP86xx/SMP87xx Watchdog driver
5 */
6
7 #include <linux/bitops.h>
8 #include <linux/clk.h>
9 #include <linux/delay.h>
10 #include <linux/io.h>
11 #include <linux/kernel.h>
12 #include <linux/module.h>
13 #include <linux/moduleparam.h>
14 #include <linux/mod_devicetable.h>
15 #include <linux/platform_device.h>
16 #include <linux/watchdog.h>
17
18 #define DEFAULT_TIMEOUT 30
19
20 static bool nowayout = WATCHDOG_NOWAYOUT;
21 module_param(nowayout, bool, 0);
22 MODULE_PARM_DESC(nowayout,
23 "Watchdog cannot be stopped once started (default="
24 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
25
26 static unsigned int timeout;
27 module_param(timeout, int, 0);
28 MODULE_PARM_DESC(timeout, "Watchdog timeout");
29
30 /*
31 * Counter counts down from programmed value. Reset asserts when
32 * the counter reaches 1.
33 */
34 #define WD_COUNTER 0
35
36 #define WD_CONFIG 4
37 #define WD_CONFIG_XTAL_IN BIT(0)
38 #define WD_CONFIG_DISABLE BIT(31)
39
40 struct tangox_wdt_device {
41 struct watchdog_device wdt;
42 void __iomem *base;
43 unsigned long clk_rate;
44 struct clk *clk;
45 };
46
tangox_wdt_set_timeout(struct watchdog_device * wdt,unsigned int new_timeout)47 static int tangox_wdt_set_timeout(struct watchdog_device *wdt,
48 unsigned int new_timeout)
49 {
50 wdt->timeout = new_timeout;
51
52 return 0;
53 }
54
tangox_wdt_start(struct watchdog_device * wdt)55 static int tangox_wdt_start(struct watchdog_device *wdt)
56 {
57 struct tangox_wdt_device *dev = watchdog_get_drvdata(wdt);
58 u32 ticks;
59
60 ticks = 1 + wdt->timeout * dev->clk_rate;
61 writel(ticks, dev->base + WD_COUNTER);
62
63 return 0;
64 }
65
tangox_wdt_stop(struct watchdog_device * wdt)66 static int tangox_wdt_stop(struct watchdog_device *wdt)
67 {
68 struct tangox_wdt_device *dev = watchdog_get_drvdata(wdt);
69
70 writel(0, dev->base + WD_COUNTER);
71
72 return 0;
73 }
74
tangox_wdt_get_timeleft(struct watchdog_device * wdt)75 static unsigned int tangox_wdt_get_timeleft(struct watchdog_device *wdt)
76 {
77 struct tangox_wdt_device *dev = watchdog_get_drvdata(wdt);
78 u32 count;
79
80 count = readl(dev->base + WD_COUNTER);
81
82 if (!count)
83 return 0;
84
85 return (count - 1) / dev->clk_rate;
86 }
87
88 static const struct watchdog_info tangox_wdt_info = {
89 .options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE,
90 .identity = "tangox watchdog",
91 };
92
tangox_wdt_restart(struct watchdog_device * wdt,unsigned long action,void * data)93 static int tangox_wdt_restart(struct watchdog_device *wdt,
94 unsigned long action, void *data)
95 {
96 struct tangox_wdt_device *dev = watchdog_get_drvdata(wdt);
97
98 writel(1, dev->base + WD_COUNTER);
99
100 return 0;
101 }
102
103 static const struct watchdog_ops tangox_wdt_ops = {
104 .start = tangox_wdt_start,
105 .stop = tangox_wdt_stop,
106 .set_timeout = tangox_wdt_set_timeout,
107 .get_timeleft = tangox_wdt_get_timeleft,
108 .restart = tangox_wdt_restart,
109 };
110
tangox_wdt_probe(struct platform_device * pdev)111 static int tangox_wdt_probe(struct platform_device *pdev)
112 {
113 struct tangox_wdt_device *dev;
114 struct resource *res;
115 u32 config;
116 int err;
117
118 dev = devm_kzalloc(&pdev->dev, sizeof(*dev), GFP_KERNEL);
119 if (!dev)
120 return -ENOMEM;
121
122 res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
123 dev->base = devm_ioremap_resource(&pdev->dev, res);
124 if (IS_ERR(dev->base))
125 return PTR_ERR(dev->base);
126
127 dev->clk = devm_clk_get(&pdev->dev, NULL);
128 if (IS_ERR(dev->clk))
129 return PTR_ERR(dev->clk);
130
131 err = clk_prepare_enable(dev->clk);
132 if (err)
133 return err;
134
135 dev->clk_rate = clk_get_rate(dev->clk);
136 if (!dev->clk_rate) {
137 err = -EINVAL;
138 goto err;
139 }
140
141 dev->wdt.parent = &pdev->dev;
142 dev->wdt.info = &tangox_wdt_info;
143 dev->wdt.ops = &tangox_wdt_ops;
144 dev->wdt.timeout = DEFAULT_TIMEOUT;
145 dev->wdt.min_timeout = 1;
146 dev->wdt.max_hw_heartbeat_ms = (U32_MAX - 1) / dev->clk_rate;
147
148 watchdog_init_timeout(&dev->wdt, timeout, &pdev->dev);
149 watchdog_set_nowayout(&dev->wdt, nowayout);
150 watchdog_set_drvdata(&dev->wdt, dev);
151
152 /*
153 * Deactivate counter if disable bit is set to avoid
154 * accidental reset.
155 */
156 config = readl(dev->base + WD_CONFIG);
157 if (config & WD_CONFIG_DISABLE)
158 writel(0, dev->base + WD_COUNTER);
159
160 writel(WD_CONFIG_XTAL_IN, dev->base + WD_CONFIG);
161
162 /*
163 * Mark as active and restart with configured timeout if
164 * already running.
165 */
166 if (readl(dev->base + WD_COUNTER)) {
167 set_bit(WDOG_HW_RUNNING, &dev->wdt.status);
168 tangox_wdt_start(&dev->wdt);
169 }
170
171 watchdog_set_restart_priority(&dev->wdt, 128);
172
173 err = watchdog_register_device(&dev->wdt);
174 if (err)
175 goto err;
176
177 platform_set_drvdata(pdev, dev);
178
179 dev_info(&pdev->dev, "SMP86xx/SMP87xx watchdog registered\n");
180
181 return 0;
182
183 err:
184 clk_disable_unprepare(dev->clk);
185 return err;
186 }
187
tangox_wdt_remove(struct platform_device * pdev)188 static int tangox_wdt_remove(struct platform_device *pdev)
189 {
190 struct tangox_wdt_device *dev = platform_get_drvdata(pdev);
191
192 tangox_wdt_stop(&dev->wdt);
193 clk_disable_unprepare(dev->clk);
194
195 watchdog_unregister_device(&dev->wdt);
196
197 return 0;
198 }
199
200 static const struct of_device_id tangox_wdt_dt_ids[] = {
201 { .compatible = "sigma,smp8642-wdt" },
202 { .compatible = "sigma,smp8759-wdt" },
203 { }
204 };
205 MODULE_DEVICE_TABLE(of, tangox_wdt_dt_ids);
206
207 static struct platform_driver tangox_wdt_driver = {
208 .probe = tangox_wdt_probe,
209 .remove = tangox_wdt_remove,
210 .driver = {
211 .name = "tangox-wdt",
212 .of_match_table = tangox_wdt_dt_ids,
213 },
214 };
215
216 module_platform_driver(tangox_wdt_driver);
217
218 MODULE_AUTHOR("Mans Rullgard <mans@mansr.com>");
219 MODULE_DESCRIPTION("SMP86xx/SMP87xx Watchdog driver");
220 MODULE_LICENSE("GPL");
221