1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * sunplus Watchdog Driver
4 *
5 * Copyright (C) 2021 Sunplus Technology Co., Ltd.
6 *
7 */
8
9#include <linux/clk.h>
10#include <linux/io.h>
11#include <linux/module.h>
12#include <linux/mod_devicetable.h>
13#include <linux/platform_device.h>
14#include <linux/reset.h>
15#include <linux/watchdog.h>
16
17#define WDT_CTRL 0x00
18#define WDT_CNT 0x04
19
20#define WDT_STOP 0x3877
21#define WDT_RESUME 0x4A4B
22#define WDT_CLRIRQ 0x7482
23#define WDT_UNLOCK 0xAB00
24#define WDT_LOCK 0xAB01
25#define WDT_CONMAX 0xDEAF
26
27/* TIMEOUT_MAX = ffff0/90kHz =11.65, so longer than 11 seconds will time out. */
28#define SP_WDT_MAX_TIMEOUT 11U
29#define SP_WDT_DEFAULT_TIMEOUT 10
30
31#define STC_CLK 90000
32
33#define DEVICE_NAME "sunplus-wdt"
34
35static unsigned int timeout;
36module_param(timeout, int, 0);
37MODULE_PARM_DESC(timeout, "Watchdog timeout in seconds");
38
39static bool nowayout = WATCHDOG_NOWAYOUT;
40module_param(nowayout, bool, 0);
41MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="
42 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
43
44struct sp_wdt_priv {
45 struct watchdog_device wdev;
46 void __iomem *base;
47 struct clk *clk;
48 struct reset_control *rstc;
49};
50
51static int sp_wdt_restart(struct watchdog_device *wdev,
52 unsigned long action, void *data)
53{
54 struct sp_wdt_priv *priv = watchdog_get_drvdata(wdd: wdev);
55 void __iomem *base = priv->base;
56
57 writel(WDT_STOP, addr: base + WDT_CTRL);
58 writel(WDT_UNLOCK, addr: base + WDT_CTRL);
59 writel(val: 0x0001, addr: base + WDT_CNT);
60 writel(WDT_LOCK, addr: base + WDT_CTRL);
61 writel(WDT_RESUME, addr: base + WDT_CTRL);
62
63 return 0;
64}
65
66static int sp_wdt_ping(struct watchdog_device *wdev)
67{
68 struct sp_wdt_priv *priv = watchdog_get_drvdata(wdd: wdev);
69 void __iomem *base = priv->base;
70 u32 count;
71
72 if (wdev->timeout > SP_WDT_MAX_TIMEOUT) {
73 /* WDT_CONMAX sets the count to the maximum (down-counting). */
74 writel(WDT_CONMAX, addr: base + WDT_CTRL);
75 } else {
76 writel(WDT_UNLOCK, addr: base + WDT_CTRL);
77 /*
78 * Watchdog timer is a 20-bit down-counting based on STC_CLK.
79 * This register bits[16:0] is from bit[19:4] of the watchdog
80 * timer counter.
81 */
82 count = (wdev->timeout * STC_CLK) >> 4;
83 writel(val: count, addr: base + WDT_CNT);
84 writel(WDT_LOCK, addr: base + WDT_CTRL);
85 }
86
87 return 0;
88}
89
90static int sp_wdt_stop(struct watchdog_device *wdev)
91{
92 struct sp_wdt_priv *priv = watchdog_get_drvdata(wdd: wdev);
93 void __iomem *base = priv->base;
94
95 writel(WDT_STOP, addr: base + WDT_CTRL);
96
97 return 0;
98}
99
100static int sp_wdt_start(struct watchdog_device *wdev)
101{
102 struct sp_wdt_priv *priv = watchdog_get_drvdata(wdd: wdev);
103 void __iomem *base = priv->base;
104
105 writel(WDT_RESUME, addr: base + WDT_CTRL);
106
107 return 0;
108}
109
110static unsigned int sp_wdt_get_timeleft(struct watchdog_device *wdev)
111{
112 struct sp_wdt_priv *priv = watchdog_get_drvdata(wdd: wdev);
113 void __iomem *base = priv->base;
114 u32 val;
115
116 val = readl(addr: base + WDT_CNT);
117 val &= 0xffff;
118 val = val << 4;
119
120 return val;
121}
122
123static const struct watchdog_info sp_wdt_info = {
124 .identity = DEVICE_NAME,
125 .options = WDIOF_SETTIMEOUT |
126 WDIOF_MAGICCLOSE |
127 WDIOF_KEEPALIVEPING,
128};
129
130static const struct watchdog_ops sp_wdt_ops = {
131 .owner = THIS_MODULE,
132 .start = sp_wdt_start,
133 .stop = sp_wdt_stop,
134 .ping = sp_wdt_ping,
135 .get_timeleft = sp_wdt_get_timeleft,
136 .restart = sp_wdt_restart,
137};
138
139static void sp_clk_disable_unprepare(void *data)
140{
141 clk_disable_unprepare(clk: data);
142}
143
144static void sp_reset_control_assert(void *data)
145{
146 reset_control_assert(rstc: data);
147}
148
149static int sp_wdt_probe(struct platform_device *pdev)
150{
151 struct device *dev = &pdev->dev;
152 struct sp_wdt_priv *priv;
153 int ret;
154
155 priv = devm_kzalloc(dev, size: sizeof(*priv), GFP_KERNEL);
156 if (!priv)
157 return -ENOMEM;
158
159 priv->clk = devm_clk_get(dev, NULL);
160 if (IS_ERR(ptr: priv->clk))
161 return dev_err_probe(dev, err: PTR_ERR(ptr: priv->clk), fmt: "Failed to get clock\n");
162
163 ret = clk_prepare_enable(clk: priv->clk);
164 if (ret)
165 return dev_err_probe(dev, err: ret, fmt: "Failed to enable clock\n");
166
167 ret = devm_add_action_or_reset(dev, sp_clk_disable_unprepare, priv->clk);
168 if (ret)
169 return ret;
170
171 /* The timer and watchdog shared the STC reset */
172 priv->rstc = devm_reset_control_get_shared(dev, NULL);
173 if (IS_ERR(ptr: priv->rstc))
174 return dev_err_probe(dev, err: PTR_ERR(ptr: priv->rstc), fmt: "Failed to get reset\n");
175
176 reset_control_deassert(rstc: priv->rstc);
177
178 ret = devm_add_action_or_reset(dev, sp_reset_control_assert, priv->rstc);
179 if (ret)
180 return ret;
181
182 priv->base = devm_platform_ioremap_resource(pdev, index: 0);
183 if (IS_ERR(ptr: priv->base))
184 return PTR_ERR(ptr: priv->base);
185
186 priv->wdev.info = &sp_wdt_info;
187 priv->wdev.ops = &sp_wdt_ops;
188 priv->wdev.timeout = SP_WDT_DEFAULT_TIMEOUT;
189 priv->wdev.max_hw_heartbeat_ms = SP_WDT_MAX_TIMEOUT * 1000;
190 priv->wdev.min_timeout = 1;
191 priv->wdev.parent = dev;
192
193 watchdog_set_drvdata(wdd: &priv->wdev, data: priv);
194 watchdog_init_timeout(wdd: &priv->wdev, timeout_parm: timeout, dev);
195 watchdog_set_nowayout(wdd: &priv->wdev, nowayout);
196 watchdog_stop_on_reboot(wdd: &priv->wdev);
197 watchdog_set_restart_priority(wdd: &priv->wdev, priority: 128);
198
199 return devm_watchdog_register_device(dev, &priv->wdev);
200}
201
202static const struct of_device_id sp_wdt_of_match[] = {
203 {.compatible = "sunplus,sp7021-wdt", },
204 { /* sentinel */ }
205};
206MODULE_DEVICE_TABLE(of, sp_wdt_of_match);
207
208static struct platform_driver sp_wdt_driver = {
209 .probe = sp_wdt_probe,
210 .driver = {
211 .name = DEVICE_NAME,
212 .of_match_table = sp_wdt_of_match,
213 },
214};
215
216module_platform_driver(sp_wdt_driver);
217
218MODULE_AUTHOR("Xiantao Hu <xt.hu@cqplus1.com>");
219MODULE_DESCRIPTION("Sunplus Watchdog Timer Driver");
220MODULE_LICENSE("GPL");
221

source code of linux/drivers/watchdog/sunplus_wdt.c