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_WVR);
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 
101 static struct watchdog_device men_z069_wdt = {
102 	.info = &men_z069_info,
103 	.ops = &men_z069_ops,
104 	.timeout = MEN_Z069_DEFAULT_TIMEOUT,
105 	.min_timeout = 1,
106 	.max_timeout = MEN_Z069_WDT_COUNTER_MAX / MEN_Z069_TIMER_FREQ,
107 };
108 
men_z069_probe(struct mcb_device * dev,const struct mcb_device_id * id)109 static int men_z069_probe(struct mcb_device *dev,
110 			  const struct mcb_device_id *id)
111 {
112 	struct men_z069_drv *drv;
113 	struct resource *mem;
114 
115 	drv = devm_kzalloc(&dev->dev, sizeof(struct men_z069_drv), GFP_KERNEL);
116 	if (!drv)
117 		return -ENOMEM;
118 
119 	mem = mcb_request_mem(dev, "z069-wdt");
120 	if (IS_ERR(mem))
121 		return PTR_ERR(mem);
122 
123 	drv->base = devm_ioremap(&dev->dev, mem->start, resource_size(mem));
124 	if (drv->base == NULL)
125 		goto release_mem;
126 
127 	drv->mem = mem;
128 
129 	drv->wdt = men_z069_wdt;
130 	watchdog_init_timeout(&drv->wdt, 0, &dev->dev);
131 	watchdog_set_nowayout(&drv->wdt, nowayout);
132 	watchdog_set_drvdata(&drv->wdt, drv);
133 	drv->wdt.parent = &dev->dev;
134 	mcb_set_drvdata(dev, drv);
135 
136 	return watchdog_register_device(&men_z069_wdt);
137 
138 release_mem:
139 	mcb_release_mem(mem);
140 	return -ENOMEM;
141 }
142 
men_z069_remove(struct mcb_device * dev)143 static void men_z069_remove(struct mcb_device *dev)
144 {
145 	struct men_z069_drv *drv = mcb_get_drvdata(dev);
146 
147 	watchdog_unregister_device(&drv->wdt);
148 	mcb_release_mem(drv->mem);
149 }
150 
151 static const struct mcb_device_id men_z069_ids[] = {
152 	{ .device = 0x45 },
153 	{ }
154 };
155 MODULE_DEVICE_TABLE(mcb, men_z069_ids);
156 
157 static struct mcb_driver men_z069_driver = {
158 	.driver = {
159 		.name = "z069-wdt",
160 		.owner = THIS_MODULE,
161 	},
162 	.probe = men_z069_probe,
163 	.remove = men_z069_remove,
164 	.id_table = men_z069_ids,
165 };
166 module_mcb_driver(men_z069_driver);
167 
168 MODULE_AUTHOR("Johannes Thumshirn <jth@kernel.org>");
169 MODULE_LICENSE("GPL v2");
170 MODULE_ALIAS("mcb:16z069");
171 MODULE_IMPORT_NS(MCB);
172