1// SPDX-License-Identifier: GPL-2.0
2/*
3 * Copyright (c) 2020 TOSHIBA CORPORATION
4 * Copyright (c) 2020 Toshiba Electronic Devices & Storage Corporation
5 * Copyright (c) 2020 Nobuhiro Iwamatsu <nobuhiro1.iwamatsu@toshiba.co.jp>
6 */
7
8#include <linux/clk.h>
9#include <linux/io.h>
10#include <linux/kernel.h>
11#include <linux/module.h>
12#include <linux/of.h>
13#include <linux/platform_device.h>
14#include <linux/watchdog.h>
15
16#define WDT_CNT 0x00
17#define WDT_MIN 0x04
18#define WDT_MAX 0x08
19#define WDT_CTL 0x0c
20#define WDT_CMD 0x10
21#define WDT_CMD_CLEAR 0x4352
22#define WDT_CMD_START_STOP 0x5354
23#define WDT_DIV 0x30
24
25#define VISCONTI_WDT_FREQ 2000000 /* 2MHz */
26#define WDT_DEFAULT_TIMEOUT 10U /* in seconds */
27
28static bool nowayout = WATCHDOG_NOWAYOUT;
29module_param(nowayout, bool, 0);
30MODULE_PARM_DESC(
31 nowayout,
32 "Watchdog cannot be stopped once started (default=" __MODULE_STRING(WATCHDOG_NOWAYOUT)")");
33
34struct visconti_wdt_priv {
35 struct watchdog_device wdev;
36 void __iomem *base;
37 u32 div;
38};
39
40static int visconti_wdt_start(struct watchdog_device *wdev)
41{
42 struct visconti_wdt_priv *priv = watchdog_get_drvdata(wdd: wdev);
43 u32 timeout = wdev->timeout * VISCONTI_WDT_FREQ;
44
45 writel(val: priv->div, addr: priv->base + WDT_DIV);
46 writel(val: 0, addr: priv->base + WDT_MIN);
47 writel(val: timeout, addr: priv->base + WDT_MAX);
48 writel(val: 0, addr: priv->base + WDT_CTL);
49 writel(WDT_CMD_START_STOP, addr: priv->base + WDT_CMD);
50
51 return 0;
52}
53
54static int visconti_wdt_stop(struct watchdog_device *wdev)
55{
56 struct visconti_wdt_priv *priv = watchdog_get_drvdata(wdd: wdev);
57
58 writel(val: 1, addr: priv->base + WDT_CTL);
59 writel(WDT_CMD_START_STOP, addr: priv->base + WDT_CMD);
60
61 return 0;
62}
63
64static int visconti_wdt_ping(struct watchdog_device *wdd)
65{
66 struct visconti_wdt_priv *priv = watchdog_get_drvdata(wdd);
67
68 writel(WDT_CMD_CLEAR, addr: priv->base + WDT_CMD);
69
70 return 0;
71}
72
73static unsigned int visconti_wdt_get_timeleft(struct watchdog_device *wdev)
74{
75 struct visconti_wdt_priv *priv = watchdog_get_drvdata(wdd: wdev);
76 u32 timeout = wdev->timeout * VISCONTI_WDT_FREQ;
77 u32 cnt = readl(addr: priv->base + WDT_CNT);
78
79 if (timeout <= cnt)
80 return 0;
81 timeout -= cnt;
82
83 return timeout / VISCONTI_WDT_FREQ;
84}
85
86static int visconti_wdt_set_timeout(struct watchdog_device *wdev, unsigned int timeout)
87{
88 u32 val;
89 struct visconti_wdt_priv *priv = watchdog_get_drvdata(wdd: wdev);
90
91 wdev->timeout = timeout;
92 val = wdev->timeout * VISCONTI_WDT_FREQ;
93
94 /* Clear counter before setting timeout because WDT expires */
95 writel(WDT_CMD_CLEAR, addr: priv->base + WDT_CMD);
96 writel(val, addr: priv->base + WDT_MAX);
97
98 return 0;
99}
100
101static const struct watchdog_info visconti_wdt_info = {
102 .options = WDIOF_SETTIMEOUT | WDIOF_MAGICCLOSE | WDIOF_KEEPALIVEPING,
103 .identity = "Visconti Watchdog",
104};
105
106static const struct watchdog_ops visconti_wdt_ops = {
107 .owner = THIS_MODULE,
108 .start = visconti_wdt_start,
109 .stop = visconti_wdt_stop,
110 .ping = visconti_wdt_ping,
111 .get_timeleft = visconti_wdt_get_timeleft,
112 .set_timeout = visconti_wdt_set_timeout,
113};
114
115static int visconti_wdt_probe(struct platform_device *pdev)
116{
117 struct watchdog_device *wdev;
118 struct visconti_wdt_priv *priv;
119 struct device *dev = &pdev->dev;
120 struct clk *clk;
121 int ret;
122 unsigned long clk_freq;
123
124 priv = devm_kzalloc(dev, size: sizeof(*priv), GFP_KERNEL);
125 if (!priv)
126 return -ENOMEM;
127
128 priv->base = devm_platform_ioremap_resource(pdev, index: 0);
129 if (IS_ERR(ptr: priv->base))
130 return PTR_ERR(ptr: priv->base);
131
132 clk = devm_clk_get_enabled(dev, NULL);
133 if (IS_ERR(ptr: clk))
134 return dev_err_probe(dev, err: PTR_ERR(ptr: clk), fmt: "Could not get clock\n");
135
136 clk_freq = clk_get_rate(clk);
137 if (!clk_freq)
138 return -EINVAL;
139
140 priv->div = clk_freq / VISCONTI_WDT_FREQ;
141
142 /* Initialize struct watchdog_device. */
143 wdev = &priv->wdev;
144 wdev->info = &visconti_wdt_info;
145 wdev->ops = &visconti_wdt_ops;
146 wdev->parent = dev;
147 wdev->min_timeout = 1;
148 wdev->max_timeout = 0xffffffff / VISCONTI_WDT_FREQ;
149 wdev->timeout = min(wdev->max_timeout, WDT_DEFAULT_TIMEOUT);
150
151 watchdog_set_drvdata(wdd: wdev, data: priv);
152 watchdog_set_nowayout(wdd: wdev, nowayout);
153 watchdog_stop_on_unregister(wdd: wdev);
154
155 /* This overrides the default timeout only if DT configuration was found */
156 ret = watchdog_init_timeout(wdd: wdev, timeout_parm: 0, dev);
157 if (ret)
158 dev_warn(dev, "Specified timeout value invalid, using default\n");
159
160 return devm_watchdog_register_device(dev, wdev);
161}
162
163static const struct of_device_id visconti_wdt_of_match[] = {
164 { .compatible = "toshiba,visconti-wdt", },
165 {}
166};
167MODULE_DEVICE_TABLE(of, visconti_wdt_of_match);
168
169static struct platform_driver visconti_wdt_driver = {
170 .driver = {
171 .name = "visconti_wdt",
172 .of_match_table = visconti_wdt_of_match,
173 },
174 .probe = visconti_wdt_probe,
175};
176module_platform_driver(visconti_wdt_driver);
177
178MODULE_DESCRIPTION("TOSHIBA Visconti Watchdog Driver");
179MODULE_AUTHOR("Nobuhiro Iwamatsu <nobuhiro1.iwamatsu@toshiba.co.jp");
180MODULE_LICENSE("GPL v2");
181

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