1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * watchdog driver for ZTE's zx2967 family
4 *
5 * Copyright (C) 2017 ZTE Ltd.
6 *
7 * Author: Baoyou Xie <baoyou.xie@linaro.org>
8 */
9
10#include <linux/clk.h>
11#include <linux/io.h>
12#include <linux/mfd/syscon.h>
13#include <linux/module.h>
14#include <linux/of_address.h>
15#include <linux/platform_device.h>
16#include <linux/regmap.h>
17#include <linux/reset.h>
18#include <linux/watchdog.h>
19
20#define ZX2967_WDT_CFG_REG			0x4
21#define ZX2967_WDT_LOAD_REG			0x8
22#define ZX2967_WDT_REFRESH_REG			0x18
23#define ZX2967_WDT_START_REG			0x1c
24
25#define ZX2967_WDT_REFRESH_MASK			GENMASK(5, 0)
26
27#define ZX2967_WDT_CFG_DIV(n)			((((n) & 0xff) - 1) << 8)
28#define ZX2967_WDT_START_EN			0x1
29
30/*
31 * Hardware magic number.
32 * When watchdog reg is written, the lowest 16 bits are valid, but
33 * the highest 16 bits should be always this number.
34 */
35#define ZX2967_WDT_WRITEKEY			(0x1234 << 16)
36#define ZX2967_WDT_VAL_MASK			GENMASK(15, 0)
37
38#define ZX2967_WDT_DIV_DEFAULT			16
39#define ZX2967_WDT_DEFAULT_TIMEOUT		32
40#define ZX2967_WDT_MIN_TIMEOUT			1
41#define ZX2967_WDT_MAX_TIMEOUT			524
42#define ZX2967_WDT_MAX_COUNT			0xffff
43
44#define ZX2967_WDT_CLK_FREQ			0x8000
45
46#define ZX2967_WDT_FLAG_REBOOT_MON		BIT(0)
47
48struct zx2967_wdt {
49	struct watchdog_device	wdt_device;
50	void __iomem		*reg_base;
51	struct clk		*clock;
52};
53
54static inline u32 zx2967_wdt_readl(struct zx2967_wdt *wdt, u16 reg)
55{
56	return readl_relaxed(wdt->reg_base + reg);
57}
58
59static inline void zx2967_wdt_writel(struct zx2967_wdt *wdt, u16 reg, u32 val)
60{
61	writel_relaxed(val | ZX2967_WDT_WRITEKEY, wdt->reg_base + reg);
62}
63
64static void zx2967_wdt_refresh(struct zx2967_wdt *wdt)
65{
66	u32 val;
67
68	val = zx2967_wdt_readl(wdt, ZX2967_WDT_REFRESH_REG);
69	/*
70	 * Bit 4-5, 1 and 2: refresh config info
71	 * Bit 2-3, 1 and 2: refresh counter
72	 * Bit 0-1, 1 and 2: refresh int-value
73	 * we shift each group value between 1 and 2 to refresh all data.
74	 */
75	val ^= ZX2967_WDT_REFRESH_MASK;
76	zx2967_wdt_writel(wdt, ZX2967_WDT_REFRESH_REG,
77			  val & ZX2967_WDT_VAL_MASK);
78}
79
80static int
81zx2967_wdt_set_timeout(struct watchdog_device *wdd, unsigned int timeout)
82{
83	struct zx2967_wdt *wdt = watchdog_get_drvdata(wdd);
84	unsigned int divisor = ZX2967_WDT_DIV_DEFAULT;
85	u32 count;
86
87	count = timeout * ZX2967_WDT_CLK_FREQ;
88	if (count > divisor * ZX2967_WDT_MAX_COUNT)
89		divisor = DIV_ROUND_UP(count, ZX2967_WDT_MAX_COUNT);
90	count = DIV_ROUND_UP(count, divisor);
91	zx2967_wdt_writel(wdt, ZX2967_WDT_CFG_REG,
92			ZX2967_WDT_CFG_DIV(divisor) & ZX2967_WDT_VAL_MASK);
93	zx2967_wdt_writel(wdt, ZX2967_WDT_LOAD_REG,
94			count & ZX2967_WDT_VAL_MASK);
95	zx2967_wdt_refresh(wdt);
96	wdd->timeout =  (count * divisor) / ZX2967_WDT_CLK_FREQ;
97
98	return 0;
99}
100
101static void __zx2967_wdt_start(struct zx2967_wdt *wdt)
102{
103	u32 val;
104
105	val = zx2967_wdt_readl(wdt, ZX2967_WDT_START_REG);
106	val |= ZX2967_WDT_START_EN;
107	zx2967_wdt_writel(wdt, ZX2967_WDT_START_REG,
108			val & ZX2967_WDT_VAL_MASK);
109}
110
111static void __zx2967_wdt_stop(struct zx2967_wdt *wdt)
112{
113	u32 val;
114
115	val = zx2967_wdt_readl(wdt, ZX2967_WDT_START_REG);
116	val &= ~ZX2967_WDT_START_EN;
117	zx2967_wdt_writel(wdt, ZX2967_WDT_START_REG,
118			val & ZX2967_WDT_VAL_MASK);
119}
120
121static int zx2967_wdt_start(struct watchdog_device *wdd)
122{
123	struct zx2967_wdt *wdt = watchdog_get_drvdata(wdd);
124
125	zx2967_wdt_set_timeout(wdd, wdd->timeout);
126	__zx2967_wdt_start(wdt);
127
128	return 0;
129}
130
131static int zx2967_wdt_stop(struct watchdog_device *wdd)
132{
133	struct zx2967_wdt *wdt = watchdog_get_drvdata(wdd);
134
135	__zx2967_wdt_stop(wdt);
136
137	return 0;
138}
139
140static int zx2967_wdt_keepalive(struct watchdog_device *wdd)
141{
142	struct zx2967_wdt *wdt = watchdog_get_drvdata(wdd);
143
144	zx2967_wdt_refresh(wdt);
145
146	return 0;
147}
148
149#define ZX2967_WDT_OPTIONS \
150	(WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE)
151static const struct watchdog_info zx2967_wdt_ident = {
152	.options          =     ZX2967_WDT_OPTIONS,
153	.identity         =	"zx2967 watchdog",
154};
155
156static const struct watchdog_ops zx2967_wdt_ops = {
157	.owner = THIS_MODULE,
158	.start = zx2967_wdt_start,
159	.stop = zx2967_wdt_stop,
160	.ping = zx2967_wdt_keepalive,
161	.set_timeout = zx2967_wdt_set_timeout,
162};
163
164static void zx2967_wdt_reset_sysctrl(struct device *dev)
165{
166	int ret;
167	void __iomem *regmap;
168	unsigned int offset, mask, config;
169	struct of_phandle_args out_args;
170
171	ret = of_parse_phandle_with_fixed_args(dev->of_node,
172			"zte,wdt-reset-sysctrl", 3, 0, &out_args);
173	if (ret)
174		return;
175
176	offset = out_args.args[0];
177	config = out_args.args[1];
178	mask = out_args.args[2];
179
180	regmap = syscon_node_to_regmap(out_args.np);
181	if (IS_ERR(regmap)) {
182		of_node_put(out_args.np);
183		return;
184	}
185
186	regmap_update_bits(regmap, offset, mask, config);
187	of_node_put(out_args.np);
188}
189
190static void zx2967_clk_disable_unprepare(void *data)
191{
192	clk_disable_unprepare(data);
193}
194
195static int zx2967_wdt_probe(struct platform_device *pdev)
196{
197	struct device *dev = &pdev->dev;
198	struct zx2967_wdt *wdt;
199	int ret;
200	struct reset_control *rstc;
201
202	wdt = devm_kzalloc(dev, sizeof(*wdt), GFP_KERNEL);
203	if (!wdt)
204		return -ENOMEM;
205
206	platform_set_drvdata(pdev, wdt);
207
208	wdt->wdt_device.info = &zx2967_wdt_ident;
209	wdt->wdt_device.ops = &zx2967_wdt_ops;
210	wdt->wdt_device.timeout = ZX2967_WDT_DEFAULT_TIMEOUT;
211	wdt->wdt_device.max_timeout = ZX2967_WDT_MAX_TIMEOUT;
212	wdt->wdt_device.min_timeout = ZX2967_WDT_MIN_TIMEOUT;
213	wdt->wdt_device.parent = dev;
214
215	wdt->reg_base = devm_platform_ioremap_resource(pdev, 0);
216	if (IS_ERR(wdt->reg_base))
217		return PTR_ERR(wdt->reg_base);
218
219	zx2967_wdt_reset_sysctrl(dev);
220
221	wdt->clock = devm_clk_get(dev, NULL);
222	if (IS_ERR(wdt->clock)) {
223		dev_err(dev, "failed to find watchdog clock source\n");
224		return PTR_ERR(wdt->clock);
225	}
226
227	ret = clk_prepare_enable(wdt->clock);
228	if (ret < 0) {
229		dev_err(dev, "failed to enable clock\n");
230		return ret;
231	}
232	ret = devm_add_action_or_reset(dev, zx2967_clk_disable_unprepare,
233				       wdt->clock);
234	if (ret)
235		return ret;
236	clk_set_rate(wdt->clock, ZX2967_WDT_CLK_FREQ);
237
238	rstc = devm_reset_control_get_exclusive(dev, NULL);
239	if (IS_ERR(rstc)) {
240		dev_err(dev, "failed to get rstc");
241		return PTR_ERR(rstc);
242	}
243
244	reset_control_assert(rstc);
245	reset_control_deassert(rstc);
246
247	watchdog_set_drvdata(&wdt->wdt_device, wdt);
248	watchdog_init_timeout(&wdt->wdt_device,
249			ZX2967_WDT_DEFAULT_TIMEOUT, dev);
250	watchdog_set_nowayout(&wdt->wdt_device, WATCHDOG_NOWAYOUT);
251
252	ret = devm_watchdog_register_device(dev, &wdt->wdt_device);
253	if (ret)
254		return ret;
255
256	dev_info(dev, "watchdog enabled (timeout=%d sec, nowayout=%d)",
257		 wdt->wdt_device.timeout, WATCHDOG_NOWAYOUT);
258
259	return 0;
260}
261
262static const struct of_device_id zx2967_wdt_match[] = {
263	{ .compatible = "zte,zx296718-wdt", },
264	{}
265};
266MODULE_DEVICE_TABLE(of, zx2967_wdt_match);
267
268static struct platform_driver zx2967_wdt_driver = {
269	.probe		= zx2967_wdt_probe,
270	.driver		= {
271		.name	= "zx2967-wdt",
272		.of_match_table	= of_match_ptr(zx2967_wdt_match),
273	},
274};
275module_platform_driver(zx2967_wdt_driver);
276
277MODULE_AUTHOR("Baoyou Xie <baoyou.xie@linaro.org>");
278MODULE_DESCRIPTION("ZTE zx2967 Watchdog Device Driver");
279MODULE_LICENSE("GPL v2");
280