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
13struct 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
29static bool nowayout = WATCHDOG_NOWAYOUT;
30module_param(nowayout, bool, 0);
31MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="
32			    __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
33
34static 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
46static 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
58static 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
71static 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
88static const struct watchdog_info men_z069_info = {
89	.options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE,
90	.identity = "MEN z069 Watchdog",
91};
92
93static 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
101static 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
134release_mem:
135	mcb_release_mem(mem);
136	return -ENOMEM;
137}
138
139static 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
147static const struct mcb_device_id men_z069_ids[] = {
148	{ .device = 0x45 },
149	{ }
150};
151MODULE_DEVICE_TABLE(mcb, men_z069_ids);
152
153static 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};
161module_mcb_driver(men_z069_driver);
162
163MODULE_AUTHOR("Johannes Thumshirn <jth@kernel.org>");
164MODULE_LICENSE("GPL v2");
165MODULE_ALIAS("mcb:16z069");
166MODULE_IMPORT_NS(MCB);
167