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 | |
28 | static bool nowayout = WATCHDOG_NOWAYOUT; |
29 | module_param(nowayout, bool, 0); |
30 | MODULE_PARM_DESC( |
31 | nowayout, |
32 | "Watchdog cannot be stopped once started (default=" __MODULE_STRING(WATCHDOG_NOWAYOUT)")" ); |
33 | |
34 | struct visconti_wdt_priv { |
35 | struct watchdog_device wdev; |
36 | void __iomem *base; |
37 | u32 div; |
38 | }; |
39 | |
40 | static 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 | |
54 | static 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 | |
64 | static 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 | |
73 | static 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 | |
86 | static 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 | |
101 | static const struct watchdog_info visconti_wdt_info = { |
102 | .options = WDIOF_SETTIMEOUT | WDIOF_MAGICCLOSE | WDIOF_KEEPALIVEPING, |
103 | .identity = "Visconti Watchdog" , |
104 | }; |
105 | |
106 | static 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 | |
115 | static 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 | |
163 | static const struct of_device_id visconti_wdt_of_match[] = { |
164 | { .compatible = "toshiba,visconti-wdt" , }, |
165 | {} |
166 | }; |
167 | MODULE_DEVICE_TABLE(of, visconti_wdt_of_match); |
168 | |
169 | static 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 | }; |
176 | module_platform_driver(visconti_wdt_driver); |
177 | |
178 | MODULE_DESCRIPTION("TOSHIBA Visconti Watchdog Driver" ); |
179 | MODULE_AUTHOR("Nobuhiro Iwamatsu <nobuhiro1.iwamatsu@toshiba.co.jp" ); |
180 | MODULE_LICENSE("GPL v2" ); |
181 | |