1// SPDX-License-Identifier: GPL-2.0+
2/*
3 * Watchdog driver for TQMx86 PLD.
4 *
5 * The watchdog supports power of 2 timeouts from 1 to 4096sec.
6 * Once started, it cannot be stopped.
7 *
8 * Based on the vendor code written by Vadim V.Vlasov
9 * <vvlasov@dev.rtsoft.ru>
10 */
11
12#include <linux/io.h>
13#include <linux/log2.h>
14#include <linux/module.h>
15#include <linux/platform_device.h>
16#include <linux/timer.h>
17#include <linux/watchdog.h>
18
19/* default timeout (secs) */
20#define WDT_TIMEOUT 32
21
22static unsigned int timeout;
23module_param(timeout, uint, 0);
24MODULE_PARM_DESC(timeout,
25	"Watchdog timeout in seconds. (1<=timeout<=4096, default="
26				__MODULE_STRING(WDT_TIMEOUT) ")");
27struct tqmx86_wdt {
28	struct watchdog_device wdd;
29	void __iomem *io_base;
30};
31
32#define TQMX86_WDCFG	0x00 /* Watchdog Configuration Register */
33#define TQMX86_WDCS	0x01 /* Watchdog Config/Status Register */
34
35static int tqmx86_wdt_start(struct watchdog_device *wdd)
36{
37	struct tqmx86_wdt *priv = watchdog_get_drvdata(wdd);
38
39	iowrite8(0x81, priv->io_base + TQMX86_WDCS);
40
41	return 0;
42}
43
44static int tqmx86_wdt_set_timeout(struct watchdog_device *wdd, unsigned int t)
45{
46	struct tqmx86_wdt *priv = watchdog_get_drvdata(wdd);
47	u8 val;
48
49	t = roundup_pow_of_two(t);
50	val = ilog2(t) | 0x90;
51	val += 3; /* values 0,1,2 correspond to 0.125,0.25,0.5s timeouts */
52	iowrite8(val, priv->io_base + TQMX86_WDCFG);
53
54	wdd->timeout = t;
55
56	return 0;
57}
58
59static const struct watchdog_info tqmx86_wdt_info = {
60	.options	= WDIOF_SETTIMEOUT |
61			  WDIOF_KEEPALIVEPING,
62	.identity	= "TQMx86 Watchdog",
63};
64
65static const struct watchdog_ops tqmx86_wdt_ops = {
66	.owner		= THIS_MODULE,
67	.start		= tqmx86_wdt_start,
68	.set_timeout	= tqmx86_wdt_set_timeout,
69};
70
71static int tqmx86_wdt_probe(struct platform_device *pdev)
72{
73	struct device *dev = &pdev->dev;
74	struct tqmx86_wdt *priv;
75	struct resource *res;
76	int err;
77
78	priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
79	if (!priv)
80		return -ENOMEM;
81
82	res = platform_get_resource(pdev, IORESOURCE_IO, 0);
83	if (!res)
84		return -ENODEV;
85
86	priv->io_base = devm_ioport_map(dev, res->start, resource_size(res));
87	if (!priv->io_base)
88		return -ENOMEM;
89
90	watchdog_set_drvdata(&priv->wdd, priv);
91
92	priv->wdd.parent = dev;
93	priv->wdd.info = &tqmx86_wdt_info;
94	priv->wdd.ops = &tqmx86_wdt_ops;
95	priv->wdd.min_timeout = 1;
96	priv->wdd.max_timeout = 4096;
97	priv->wdd.max_hw_heartbeat_ms = 4096*1000;
98	priv->wdd.timeout = WDT_TIMEOUT;
99
100	watchdog_init_timeout(&priv->wdd, timeout, dev);
101	watchdog_set_nowayout(&priv->wdd, WATCHDOG_NOWAYOUT);
102
103	tqmx86_wdt_set_timeout(&priv->wdd, priv->wdd.timeout);
104
105	err = devm_watchdog_register_device(dev, &priv->wdd);
106	if (err)
107		return err;
108
109	dev_info(dev, "TQMx86 watchdog\n");
110
111	return 0;
112}
113
114static struct platform_driver tqmx86_wdt_driver = {
115	.driver		= {
116		.name	= "tqmx86-wdt",
117	},
118	.probe		= tqmx86_wdt_probe,
119};
120
121module_platform_driver(tqmx86_wdt_driver);
122
123MODULE_AUTHOR("Andrew Lunn <andrew@lunn.ch>");
124MODULE_DESCRIPTION("TQMx86 Watchdog");
125MODULE_ALIAS("platform:tqmx86-wdt");
126MODULE_LICENSE("GPL");
127