tjh.dev
Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
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linux
1// SPDX-License-Identifier: GPL-2.0
2/*
3 * Driver for the Renesas Window Watchdog Timer (WWDT)
4 *
5 * The WWDT can only be setup once after boot. Because we cannot know if this
6 * already happened in early boot stages, it is mandated that the firmware
7 * configures the watchdog. Linux then adapts according to the given setup.
8 * Note that this watchdog reports in the default configuration an overflow to
9 * the Error Control Module which then decides further actions. Or the WWDT is
10 * configured to generate an interrupt.
11 */
12
13#include <linux/bitfield.h>
14#include <linux/clk.h>
15#include <linux/interrupt.h>
16#include <linux/io.h>
17#include <linux/kernel.h>
18#include <linux/module.h>
19#include <linux/of.h>
20#include <linux/platform_device.h>
21#include <linux/watchdog.h>
22
23#define WDTA0WDTE 0x00
24#define WDTA0RUN BIT(7)
25#define WDTA0_KEY 0x2c
26
27#define WDTA0MD 0x0c
28#define WDTA0OVF(x) FIELD_GET(GENMASK(6, 4), x)
29#define WDTA0WIE BIT(3)
30#define WDTA0ERM BIT(2)
31#define WDTA0WS(x) FIELD_GET(GENMASK(1, 0), x)
32
33struct wwdt_priv {
34 void __iomem *base;
35 struct watchdog_device wdev;
36};
37
38static int wwdt_start(struct watchdog_device *wdev)
39{
40 struct wwdt_priv *priv = container_of(wdev, struct wwdt_priv, wdev);
41
42 writeb(WDTA0RUN | WDTA0_KEY, priv->base + WDTA0WDTE);
43 return 0;
44}
45
46static const struct watchdog_info wwdt_ident = {
47 .options = WDIOF_KEEPALIVEPING | WDIOF_ALARMONLY,
48 .identity = "Renesas Window Watchdog",
49};
50
51static const struct watchdog_ops wwdt_ops = {
52 .owner = THIS_MODULE,
53 .start = wwdt_start,
54};
55
56static irqreturn_t wwdt_error_irq(int irq, void *dev_id)
57{
58 struct device *dev = dev_id;
59
60 dev_warn(dev, "Watchdog timed out\n");
61 return IRQ_HANDLED;
62}
63
64static irqreturn_t wwdt_pretimeout_irq(int irq, void *dev_id)
65{
66 struct watchdog_device *wdev = dev_id;
67
68 watchdog_notify_pretimeout(wdev);
69 return IRQ_HANDLED;
70}
71
72static int wwdt_probe(struct platform_device *pdev)
73{
74 struct device *dev = &pdev->dev;
75 struct wwdt_priv *priv;
76 struct watchdog_device *wdev;
77 struct clk *clk;
78 unsigned long rate;
79 unsigned int interval, window_size;
80 int ret;
81 u8 val;
82
83 priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
84 if (!priv)
85 return -ENOMEM;
86
87 priv->base = devm_platform_ioremap_resource(pdev, 0);
88 if (IS_ERR(priv->base))
89 return PTR_ERR(priv->base);
90
91 clk = devm_clk_get(dev, "cnt");
92 if (IS_ERR(clk))
93 return PTR_ERR(clk);
94
95 rate = clk_get_rate(clk);
96 if (!rate)
97 return -EINVAL;
98
99 wdev = &priv->wdev;
100
101 val = readb(priv->base + WDTA0WDTE);
102 if (val & WDTA0RUN)
103 set_bit(WDOG_HW_RUNNING, &wdev->status);
104
105 val = readb(priv->base + WDTA0MD);
106 interval = 1 << (9 + WDTA0OVF(val));
107 /* size of the closed(!) window per mille */
108 window_size = 250 * (3 - WDTA0WS(val));
109
110 wdev->info = &wwdt_ident;
111 wdev->ops = &wwdt_ops;
112 wdev->parent = dev;
113 wdev->min_hw_heartbeat_ms = window_size * interval / rate;
114 wdev->max_hw_heartbeat_ms = 1000 * interval / rate;
115 wdev->timeout = DIV_ROUND_UP(wdev->max_hw_heartbeat_ms, 1000);
116 watchdog_set_nowayout(wdev, true);
117
118 if (!(val & WDTA0ERM)) {
119 ret = platform_get_irq_byname(pdev, "error");
120 if (ret < 0)
121 return ret;
122
123 ret = devm_request_threaded_irq(dev, ret, NULL, wwdt_error_irq,
124 IRQF_ONESHOT, NULL, dev);
125 if (ret < 0)
126 return ret;
127 }
128
129 if (val & WDTA0WIE) {
130 ret = platform_get_irq_byname(pdev, "pretimeout");
131 if (ret < 0)
132 return ret;
133
134 ret = devm_request_threaded_irq(dev, ret, NULL, wwdt_pretimeout_irq,
135 IRQF_ONESHOT, NULL, wdev);
136 if (ret < 0)
137 return ret;
138 }
139
140 devm_watchdog_register_device(dev, wdev);
141
142 return 0;
143}
144
145static const struct of_device_id renesas_wwdt_ids[] = {
146 { .compatible = "renesas,rcar-gen3-wwdt", },
147 { .compatible = "renesas,rcar-gen4-wwdt", },
148 { /* sentinel */ }
149};
150MODULE_DEVICE_TABLE(of, renesas_wwdt_ids);
151
152static struct platform_driver renesas_wwdt_driver = {
153 .driver = {
154 .name = "renesas_wwdt",
155 .of_match_table = renesas_wwdt_ids,
156 },
157 .probe = wwdt_probe,
158};
159module_platform_driver(renesas_wwdt_driver);
160
161MODULE_DESCRIPTION("Renesas Window Watchdog (WWDT) Driver");
162MODULE_LICENSE("GPL");
163MODULE_AUTHOR("Wolfram Sang <wsa+renesas@sang-engineering.com>");