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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 <[email protected]>
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(wdev);
43 u32 timeout = wdev->timeout * VISCONTI_WDT_FREQ;
44
45 writel(priv->div, priv->base + WDT_DIV);
46 writel(0, priv->base + WDT_MIN);
47 writel(timeout, priv->base + WDT_MAX);
48 writel(0, priv->base + WDT_CTL);
49 writel(WDT_CMD_START_STOP, 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(wdev);
57
58 writel(1, priv->base + WDT_CTL);
59 writel(WDT_CMD_START_STOP, 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, 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(wdev);
76 u32 timeout = wdev->timeout * VISCONTI_WDT_FREQ;
77 u32 cnt = readl(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(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, priv->base + WDT_CMD);
96 writel(val, 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 unsigned long clk_freq;
122
123 priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
124 if (!priv)
125 return -ENOMEM;
126
127 priv->base = devm_platform_ioremap_resource(pdev, 0);
128 if (IS_ERR(priv->base))
129 return PTR_ERR(priv->base);
130
131 clk = devm_clk_get_enabled(dev, NULL);
132 if (IS_ERR(clk))
133 return dev_err_probe(dev, PTR_ERR(clk), "Could not get clock\n");
134
135 clk_freq = clk_get_rate(clk);
136 if (!clk_freq)
137 return -EINVAL;
138
139 priv->div = clk_freq / VISCONTI_WDT_FREQ;
140
141 /* Initialize struct watchdog_device. */
142 wdev = &priv->wdev;
143 wdev->info = &visconti_wdt_info;
144 wdev->ops = &visconti_wdt_ops;
145 wdev->parent = dev;
146 wdev->min_timeout = 1;
147 wdev->max_timeout = 0xffffffff / VISCONTI_WDT_FREQ;
148 wdev->timeout = min(wdev->max_timeout, WDT_DEFAULT_TIMEOUT);
149
150 watchdog_set_drvdata(wdev, priv);
151 watchdog_set_nowayout(wdev, nowayout);
152 watchdog_stop_on_unregister(wdev);
153
154 /* This overrides the default timeout only if DT configuration was found */
155 watchdog_init_timeout(wdev, 0, dev);
156
157 return devm_watchdog_register_device(dev, wdev);
158}
159
160static const struct of_device_id visconti_wdt_of_match[] = {
161 { .compatible = "toshiba,visconti-wdt", },
162 {}
163};
164MODULE_DEVICE_TABLE(of, visconti_wdt_of_match);
165
166static struct platform_driver visconti_wdt_driver = {
167 .driver = {
168 .name = "visconti_wdt",
169 .of_match_table = visconti_wdt_of_match,
170 },
171 .probe = visconti_wdt_probe,
172};
173module_platform_driver(visconti_wdt_driver);
174
175MODULE_DESCRIPTION("TOSHIBA Visconti Watchdog Driver");
176MODULE_AUTHOR("Nobuhiro Iwamatsu <[email protected]");
177MODULE_LICENSE("GPL v2");