1 // SPDX-License-Identifier: GPL-2.0
2 /*
3 * Watchdog driver for the MEN z069 IP-Core
4 *
5 * Copyright (C) 2018 Johannes Thumshirn <jth@kernel.org>
6 */
7 #include <linux/io.h>
8 #include <linux/kernel.h>
9 #include <linux/mcb.h>
10 #include <linux/module.h>
11 #include <linux/watchdog.h>
12
13 struct men_z069_drv {
14 struct watchdog_device wdt;
15 void __iomem *base;
16 struct resource *mem;
17 };
18
19 #define MEN_Z069_WTR 0x10
20 #define MEN_Z069_WTR_WDEN BIT(15)
21 #define MEN_Z069_WTR_WDET_MASK 0x7fff
22 #define MEN_Z069_WVR 0x14
23
24 #define MEN_Z069_TIMER_FREQ 500 /* 500 Hz */
25 #define MEN_Z069_WDT_COUNTER_MIN 1
26 #define MEN_Z069_WDT_COUNTER_MAX 0x7fff
27 #define MEN_Z069_DEFAULT_TIMEOUT 30
28
29 static bool nowayout = WATCHDOG_NOWAYOUT;
30 module_param(nowayout, bool, 0);
31 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="
32 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
33
men_z069_wdt_start(struct watchdog_device * wdt)34 static int men_z069_wdt_start(struct watchdog_device *wdt)
35 {
36 struct men_z069_drv *drv = watchdog_get_drvdata(wdt);
37 u16 val;
38
39 val = readw(drv->base + MEN_Z069_WTR);
40 val |= MEN_Z069_WTR_WDEN;
41 writew(val, drv->base + MEN_Z069_WTR);
42
43 return 0;
44 }
45
men_z069_wdt_stop(struct watchdog_device * wdt)46 static int men_z069_wdt_stop(struct watchdog_device *wdt)
47 {
48 struct men_z069_drv *drv = watchdog_get_drvdata(wdt);
49 u16 val;
50
51 val = readw(drv->base + MEN_Z069_WTR);
52 val &= ~MEN_Z069_WTR_WDEN;
53 writew(val, drv->base + MEN_Z069_WTR);
54
55 return 0;
56 }
57
men_z069_wdt_ping(struct watchdog_device * wdt)58 static int men_z069_wdt_ping(struct watchdog_device *wdt)
59 {
60 struct men_z069_drv *drv = watchdog_get_drvdata(wdt);
61 u16 val;
62
63 /* The watchdog trigger value toggles between 0x5555 and 0xaaaa */
64 val = readw(drv->base + MEN_Z069_WVR);
65 val ^= 0xffff;
66 writew(val, drv->base + MEN_Z069_WVR);
67
68 return 0;
69 }
70
men_z069_wdt_set_timeout(struct watchdog_device * wdt,unsigned int timeout)71 static int men_z069_wdt_set_timeout(struct watchdog_device *wdt,
72 unsigned int timeout)
73 {
74 struct men_z069_drv *drv = watchdog_get_drvdata(wdt);
75 u16 reg, val, ena;
76
77 wdt->timeout = timeout;
78 val = timeout * MEN_Z069_TIMER_FREQ;
79
80 reg = readw(drv->base + MEN_Z069_WTR);
81 ena = reg & MEN_Z069_WTR_WDEN;
82 reg = ena | val;
83 writew(reg, drv->base + MEN_Z069_WTR);
84
85 return 0;
86 }
87
88 static const struct watchdog_info men_z069_info = {
89 .options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE,
90 .identity = "MEN z069 Watchdog",
91 };
92
93 static const struct watchdog_ops men_z069_ops = {
94 .owner = THIS_MODULE,
95 .start = men_z069_wdt_start,
96 .stop = men_z069_wdt_stop,
97 .ping = men_z069_wdt_ping,
98 .set_timeout = men_z069_wdt_set_timeout,
99 };
100
men_z069_probe(struct mcb_device * dev,const struct mcb_device_id * id)101 static int men_z069_probe(struct mcb_device *dev,
102 const struct mcb_device_id *id)
103 {
104 struct men_z069_drv *drv;
105 struct resource *mem;
106
107 drv = devm_kzalloc(&dev->dev, sizeof(struct men_z069_drv), GFP_KERNEL);
108 if (!drv)
109 return -ENOMEM;
110
111 mem = mcb_request_mem(dev, "z069-wdt");
112 if (IS_ERR(mem))
113 return PTR_ERR(mem);
114
115 drv->base = devm_ioremap(&dev->dev, mem->start, resource_size(mem));
116 if (drv->base == NULL)
117 goto release_mem;
118
119 drv->mem = mem;
120 drv->wdt.info = &men_z069_info;
121 drv->wdt.ops = &men_z069_ops;
122 drv->wdt.timeout = MEN_Z069_DEFAULT_TIMEOUT;
123 drv->wdt.min_timeout = 1;
124 drv->wdt.max_timeout = MEN_Z069_WDT_COUNTER_MAX / MEN_Z069_TIMER_FREQ;
125
126 watchdog_init_timeout(&drv->wdt, 0, &dev->dev);
127 watchdog_set_nowayout(&drv->wdt, nowayout);
128 watchdog_set_drvdata(&drv->wdt, drv);
129 drv->wdt.parent = &dev->dev;
130 mcb_set_drvdata(dev, drv);
131
132 return watchdog_register_device(&drv->wdt);
133
134 release_mem:
135 mcb_release_mem(mem);
136 return -ENOMEM;
137 }
138
men_z069_remove(struct mcb_device * dev)139 static void men_z069_remove(struct mcb_device *dev)
140 {
141 struct men_z069_drv *drv = mcb_get_drvdata(dev);
142
143 watchdog_unregister_device(&drv->wdt);
144 mcb_release_mem(drv->mem);
145 }
146
147 static const struct mcb_device_id men_z069_ids[] = {
148 { .device = 0x45 },
149 { }
150 };
151 MODULE_DEVICE_TABLE(mcb, men_z069_ids);
152
153 static struct mcb_driver men_z069_driver = {
154 .driver = {
155 .name = "z069-wdt",
156 },
157 .probe = men_z069_probe,
158 .remove = men_z069_remove,
159 .id_table = men_z069_ids,
160 };
161 module_mcb_driver(men_z069_driver);
162
163 MODULE_AUTHOR("Johannes Thumshirn <jth@kernel.org>");
164 MODULE_LICENSE("GPL v2");
165 MODULE_ALIAS("mcb:16z069");
166 MODULE_IMPORT_NS(MCB);
167
