1// SPDX-License-Identifier: GPL-2.0
2/*
3 * Watchdog driver for the UniPhier watchdog timer
4 *
5 * (c) Copyright 2014 Panasonic Corporation
6 * (c) Copyright 2016 Socionext Inc.
7 * All rights reserved.
8 */
9
10#include <linux/bitops.h>
11#include <linux/mfd/syscon.h>
12#include <linux/module.h>
13#include <linux/of.h>
14#include <linux/platform_device.h>
15#include <linux/regmap.h>
16#include <linux/watchdog.h>
17
18/* WDT timer setting register */
19#define WDTTIMSET			0x3004
20#define   WDTTIMSET_PERIOD_MASK		(0xf << 0)
21#define   WDTTIMSET_PERIOD_1_SEC	(0x3 << 0)
22
23/* WDT reset selection register */
24#define WDTRSTSEL			0x3008
25#define   WDTRSTSEL_RSTSEL_MASK		(0x3 << 0)
26#define   WDTRSTSEL_RSTSEL_BOTH		(0x0 << 0)
27#define   WDTRSTSEL_RSTSEL_IRQ_ONLY	(0x2 << 0)
28
29/* WDT control register */
30#define WDTCTRL				0x300c
31#define   WDTCTRL_STATUS		BIT(8)
32#define   WDTCTRL_CLEAR			BIT(1)
33#define   WDTCTRL_ENABLE		BIT(0)
34
35#define SEC_TO_WDTTIMSET_PRD(sec) \
36		(ilog2(sec) + WDTTIMSET_PERIOD_1_SEC)
37
38#define WDTST_TIMEOUT			1000 /* usec */
39
40#define WDT_DEFAULT_TIMEOUT		64   /* Default is 64 seconds */
41#define WDT_PERIOD_MIN			1
42#define WDT_PERIOD_MAX			128
43
44static unsigned int timeout = 0;
45static bool nowayout = WATCHDOG_NOWAYOUT;
46
47struct uniphier_wdt_dev {
48	struct watchdog_device wdt_dev;
49	struct regmap	*regmap;
50};
51
52/*
53 * UniPhier Watchdog operations
54 */
55static int uniphier_watchdog_ping(struct watchdog_device *w)
56{
57	struct uniphier_wdt_dev *wdev = watchdog_get_drvdata(w);
58	unsigned int val;
59	int ret;
60
61	/* Clear counter */
62	ret = regmap_write_bits(wdev->regmap, WDTCTRL,
63				WDTCTRL_CLEAR, WDTCTRL_CLEAR);
64	if (!ret)
65		/*
66		 * As SoC specification, after clear counter,
67		 * it needs to wait until counter status is 1.
68		 */
69		ret = regmap_read_poll_timeout(wdev->regmap, WDTCTRL, val,
70					       (val & WDTCTRL_STATUS),
71					       0, WDTST_TIMEOUT);
72
73	return ret;
74}
75
76static int __uniphier_watchdog_start(struct regmap *regmap, unsigned int sec)
77{
78	unsigned int val;
79	int ret;
80
81	ret = regmap_read_poll_timeout(regmap, WDTCTRL, val,
82				       !(val & WDTCTRL_STATUS),
83				       0, WDTST_TIMEOUT);
84	if (ret)
85		return ret;
86
87	/* Setup period */
88	ret = regmap_write(regmap, WDTTIMSET,
89			   SEC_TO_WDTTIMSET_PRD(sec));
90	if (ret)
91		return ret;
92
93	/* Enable and clear watchdog */
94	ret = regmap_write(regmap, WDTCTRL, WDTCTRL_ENABLE | WDTCTRL_CLEAR);
95	if (!ret)
96		/*
97		 * As SoC specification, after clear counter,
98		 * it needs to wait until counter status is 1.
99		 */
100		ret = regmap_read_poll_timeout(regmap, WDTCTRL, val,
101					       (val & WDTCTRL_STATUS),
102					       0, WDTST_TIMEOUT);
103
104	return ret;
105}
106
107static int __uniphier_watchdog_stop(struct regmap *regmap)
108{
109	/* Disable and stop watchdog */
110	return regmap_write_bits(regmap, WDTCTRL, WDTCTRL_ENABLE, 0);
111}
112
113static int __uniphier_watchdog_restart(struct regmap *regmap, unsigned int sec)
114{
115	int ret;
116
117	ret = __uniphier_watchdog_stop(regmap);
118	if (ret)
119		return ret;
120
121	return __uniphier_watchdog_start(regmap, sec);
122}
123
124static int uniphier_watchdog_start(struct watchdog_device *w)
125{
126	struct uniphier_wdt_dev *wdev = watchdog_get_drvdata(w);
127	unsigned int tmp_timeout;
128
129	tmp_timeout = roundup_pow_of_two(w->timeout);
130
131	return __uniphier_watchdog_start(wdev->regmap, tmp_timeout);
132}
133
134static int uniphier_watchdog_stop(struct watchdog_device *w)
135{
136	struct uniphier_wdt_dev *wdev = watchdog_get_drvdata(w);
137
138	return __uniphier_watchdog_stop(wdev->regmap);
139}
140
141static int uniphier_watchdog_set_timeout(struct watchdog_device *w,
142					 unsigned int t)
143{
144	struct uniphier_wdt_dev *wdev = watchdog_get_drvdata(w);
145	unsigned int tmp_timeout;
146	int ret;
147
148	tmp_timeout = roundup_pow_of_two(t);
149	if (tmp_timeout == w->timeout)
150		return 0;
151
152	if (watchdog_active(w)) {
153		ret = __uniphier_watchdog_restart(wdev->regmap, tmp_timeout);
154		if (ret)
155			return ret;
156	}
157
158	w->timeout = tmp_timeout;
159
160	return 0;
161}
162
163/*
164 * Kernel Interfaces
165 */
166static const struct watchdog_info uniphier_wdt_info = {
167	.identity	= "uniphier-wdt",
168	.options	= WDIOF_SETTIMEOUT |
169			  WDIOF_KEEPALIVEPING |
170			  WDIOF_MAGICCLOSE |
171			  WDIOF_OVERHEAT,
172};
173
174static const struct watchdog_ops uniphier_wdt_ops = {
175	.owner		= THIS_MODULE,
176	.start		= uniphier_watchdog_start,
177	.stop		= uniphier_watchdog_stop,
178	.ping		= uniphier_watchdog_ping,
179	.set_timeout	= uniphier_watchdog_set_timeout,
180};
181
182static int uniphier_wdt_probe(struct platform_device *pdev)
183{
184	struct device *dev = &pdev->dev;
185	struct uniphier_wdt_dev *wdev;
186	struct regmap *regmap;
187	struct device_node *parent;
188	int ret;
189
190	wdev = devm_kzalloc(dev, sizeof(*wdev), GFP_KERNEL);
191	if (!wdev)
192		return -ENOMEM;
193
194	parent = of_get_parent(dev->of_node); /* parent should be syscon node */
195	regmap = syscon_node_to_regmap(parent);
196	of_node_put(parent);
197	if (IS_ERR(regmap))
198		return PTR_ERR(regmap);
199
200	wdev->regmap = regmap;
201	wdev->wdt_dev.info = &uniphier_wdt_info;
202	wdev->wdt_dev.ops = &uniphier_wdt_ops;
203	wdev->wdt_dev.max_timeout = WDT_PERIOD_MAX;
204	wdev->wdt_dev.min_timeout = WDT_PERIOD_MIN;
205	wdev->wdt_dev.timeout = WDT_DEFAULT_TIMEOUT;
206	wdev->wdt_dev.parent = dev;
207
208	watchdog_init_timeout(&wdev->wdt_dev, timeout, dev);
209	watchdog_set_nowayout(&wdev->wdt_dev, nowayout);
210	watchdog_stop_on_reboot(&wdev->wdt_dev);
211
212	watchdog_set_drvdata(&wdev->wdt_dev, wdev);
213
214	uniphier_watchdog_stop(&wdev->wdt_dev);
215	ret = regmap_write(wdev->regmap, WDTRSTSEL, WDTRSTSEL_RSTSEL_BOTH);
216	if (ret)
217		return ret;
218
219	ret = devm_watchdog_register_device(dev, &wdev->wdt_dev);
220	if (ret)
221		return ret;
222
223	dev_info(dev, "watchdog driver (timeout=%d sec, nowayout=%d)\n",
224		 wdev->wdt_dev.timeout, nowayout);
225
226	return 0;
227}
228
229static const struct of_device_id uniphier_wdt_dt_ids[] = {
230	{ .compatible = "socionext,uniphier-wdt" },
231	{ /* sentinel */ }
232};
233MODULE_DEVICE_TABLE(of, uniphier_wdt_dt_ids);
234
235static struct platform_driver uniphier_wdt_driver = {
236	.probe		= uniphier_wdt_probe,
237	.driver		= {
238		.name		= "uniphier-wdt",
239		.of_match_table	= uniphier_wdt_dt_ids,
240	},
241};
242
243module_platform_driver(uniphier_wdt_driver);
244
245module_param(timeout, uint, 0000);
246MODULE_PARM_DESC(timeout,
247	"Watchdog timeout seconds in power of 2. (0 < timeout < 128, default="
248				__MODULE_STRING(WDT_DEFAULT_TIMEOUT) ")");
249
250module_param(nowayout, bool, 0000);
251MODULE_PARM_DESC(nowayout,
252	"Watchdog cannot be stopped once started (default="
253				__MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
254
255MODULE_AUTHOR("Keiji Hayashibara <hayashibara.keiji@socionext.com>");
256MODULE_DESCRIPTION("UniPhier Watchdog Device Driver");
257MODULE_LICENSE("GPL v2");
258