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
48 struct zx2967_wdt {
49 struct watchdog_device wdt_device;
50 void __iomem *reg_base;
51 struct clk *clock;
52 };
53
zx2967_wdt_readl(struct zx2967_wdt * wdt,u16 reg)54 static inline u32 zx2967_wdt_readl(struct zx2967_wdt *wdt, u16 reg)
55 {
56 return readl_relaxed(wdt->reg_base + reg);
57 }
58
zx2967_wdt_writel(struct zx2967_wdt * wdt,u16 reg,u32 val)59 static 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
zx2967_wdt_refresh(struct zx2967_wdt * wdt)64 static 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
80 static int
zx2967_wdt_set_timeout(struct watchdog_device * wdd,unsigned int timeout)81 zx2967_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
__zx2967_wdt_start(struct zx2967_wdt * wdt)101 static 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
__zx2967_wdt_stop(struct zx2967_wdt * wdt)111 static 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
zx2967_wdt_start(struct watchdog_device * wdd)121 static 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
zx2967_wdt_stop(struct watchdog_device * wdd)131 static 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
zx2967_wdt_keepalive(struct watchdog_device * wdd)140 static 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)
151 static const struct watchdog_info zx2967_wdt_ident = {
152 .options = ZX2967_WDT_OPTIONS,
153 .identity = "zx2967 watchdog",
154 };
155
156 static 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
zx2967_wdt_reset_sysctrl(struct device * dev)164 static 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
zx2967_clk_disable_unprepare(void * data)190 static void zx2967_clk_disable_unprepare(void *data)
191 {
192 clk_disable_unprepare(data);
193 }
194
zx2967_wdt_probe(struct platform_device * pdev)195 static 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
262 static const struct of_device_id zx2967_wdt_match[] = {
263 { .compatible = "zte,zx296718-wdt", },
264 {}
265 };
266 MODULE_DEVICE_TABLE(of, zx2967_wdt_match);
267
268 static 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 };
275 module_platform_driver(zx2967_wdt_driver);
276
277 MODULE_AUTHOR("Baoyou Xie <baoyou.xie@linaro.org>");
278 MODULE_DESCRIPTION("ZTE zx2967 Watchdog Device Driver");
279 MODULE_LICENSE("GPL v2");
280
