tjh.dev
Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
1/*
2 * Watchdog driver for Renesas WDT watchdog
3 *
4 * Copyright (C) 2015-16 Wolfram Sang, Sang Engineering <wsa@sang-engineering.com>
5 * Copyright (C) 2015-16 Renesas Electronics Corporation
6 *
7 * This program is free software; you can redistribute it and/or modify it
8 * under the terms of the GNU General Public License version 2 as published by
9 * the Free Software Foundation.
10 */
11#include <linux/bitops.h>
12#include <linux/clk.h>
13#include <linux/io.h>
14#include <linux/kernel.h>
15#include <linux/module.h>
16#include <linux/of.h>
17#include <linux/platform_device.h>
18#include <linux/pm_runtime.h>
19#include <linux/watchdog.h>
20
21#define RWTCNT 0
22#define RWTCSRA 4
23#define RWTCSRA_WOVF BIT(4)
24#define RWTCSRA_WRFLG BIT(5)
25#define RWTCSRA_TME BIT(7)
26
27#define RWDT_DEFAULT_TIMEOUT 60U
28
29static const unsigned int clk_divs[] = { 1, 4, 16, 32, 64, 128, 1024 };
30
31static bool nowayout = WATCHDOG_NOWAYOUT;
32module_param(nowayout, bool, 0);
33MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="
34 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
35
36struct rwdt_priv {
37 void __iomem *base;
38 struct watchdog_device wdev;
39 struct clk *clk;
40 unsigned int clks_per_sec;
41 u8 cks;
42};
43
44static void rwdt_write(struct rwdt_priv *priv, u32 val, unsigned int reg)
45{
46 if (reg == RWTCNT)
47 val |= 0x5a5a0000;
48 else
49 val |= 0xa5a5a500;
50
51 writel_relaxed(val, priv->base + reg);
52}
53
54static int rwdt_init_timeout(struct watchdog_device *wdev)
55{
56 struct rwdt_priv *priv = watchdog_get_drvdata(wdev);
57
58 rwdt_write(priv, 65536 - wdev->timeout * priv->clks_per_sec, RWTCNT);
59
60 return 0;
61}
62
63static int rwdt_start(struct watchdog_device *wdev)
64{
65 struct rwdt_priv *priv = watchdog_get_drvdata(wdev);
66
67 clk_prepare_enable(priv->clk);
68
69 rwdt_write(priv, priv->cks, RWTCSRA);
70 rwdt_init_timeout(wdev);
71
72 while (readb_relaxed(priv->base + RWTCSRA) & RWTCSRA_WRFLG)
73 cpu_relax();
74
75 rwdt_write(priv, priv->cks | RWTCSRA_TME, RWTCSRA);
76
77 return 0;
78}
79
80static int rwdt_stop(struct watchdog_device *wdev)
81{
82 struct rwdt_priv *priv = watchdog_get_drvdata(wdev);
83
84 rwdt_write(priv, priv->cks, RWTCSRA);
85 clk_disable_unprepare(priv->clk);
86
87 return 0;
88}
89
90static unsigned int rwdt_get_timeleft(struct watchdog_device *wdev)
91{
92 struct rwdt_priv *priv = watchdog_get_drvdata(wdev);
93 u16 val = readw_relaxed(priv->base + RWTCNT);
94
95 return DIV_ROUND_CLOSEST(65536 - val, priv->clks_per_sec);
96}
97
98static const struct watchdog_info rwdt_ident = {
99 .options = WDIOF_MAGICCLOSE | WDIOF_KEEPALIVEPING | WDIOF_SETTIMEOUT,
100 .identity = "Renesas WDT Watchdog",
101};
102
103static const struct watchdog_ops rwdt_ops = {
104 .owner = THIS_MODULE,
105 .start = rwdt_start,
106 .stop = rwdt_stop,
107 .ping = rwdt_init_timeout,
108 .get_timeleft = rwdt_get_timeleft,
109};
110
111static int rwdt_probe(struct platform_device *pdev)
112{
113 struct rwdt_priv *priv;
114 struct resource *res;
115 unsigned long rate;
116 unsigned int clks_per_sec;
117 int ret, i;
118
119 priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL);
120 if (!priv)
121 return -ENOMEM;
122
123 res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
124 priv->base = devm_ioremap_resource(&pdev->dev, res);
125 if (IS_ERR(priv->base))
126 return PTR_ERR(priv->base);
127
128 priv->clk = devm_clk_get(&pdev->dev, NULL);
129 if (IS_ERR(priv->clk))
130 return PTR_ERR(priv->clk);
131
132 rate = clk_get_rate(priv->clk);
133 if (!rate)
134 return -ENOENT;
135
136 for (i = ARRAY_SIZE(clk_divs) - 1; i >= 0; i--) {
137 clks_per_sec = DIV_ROUND_UP(rate, clk_divs[i]);
138 if (clks_per_sec) {
139 priv->clks_per_sec = clks_per_sec;
140 priv->cks = i;
141 break;
142 }
143 }
144
145 if (!clks_per_sec) {
146 dev_err(&pdev->dev, "Can't find suitable clock divider\n");
147 return -ERANGE;
148 }
149
150 pm_runtime_enable(&pdev->dev);
151 pm_runtime_get_sync(&pdev->dev);
152
153 priv->wdev.info = &rwdt_ident,
154 priv->wdev.ops = &rwdt_ops,
155 priv->wdev.parent = &pdev->dev;
156 priv->wdev.min_timeout = 1;
157 priv->wdev.max_timeout = 65536 / clks_per_sec;
158 priv->wdev.timeout = min(priv->wdev.max_timeout, RWDT_DEFAULT_TIMEOUT);
159
160 platform_set_drvdata(pdev, priv);
161 watchdog_set_drvdata(&priv->wdev, priv);
162 watchdog_set_nowayout(&priv->wdev, nowayout);
163
164 /* This overrides the default timeout only if DT configuration was found */
165 ret = watchdog_init_timeout(&priv->wdev, 0, &pdev->dev);
166 if (ret)
167 dev_warn(&pdev->dev, "Specified timeout value invalid, using default\n");
168
169 ret = watchdog_register_device(&priv->wdev);
170 if (ret < 0) {
171 pm_runtime_put(&pdev->dev);
172 pm_runtime_disable(&pdev->dev);
173 return ret;
174 }
175
176 return 0;
177}
178
179static int rwdt_remove(struct platform_device *pdev)
180{
181 struct rwdt_priv *priv = platform_get_drvdata(pdev);
182
183 watchdog_unregister_device(&priv->wdev);
184 pm_runtime_put(&pdev->dev);
185 pm_runtime_disable(&pdev->dev);
186
187 return 0;
188}
189
190/*
191 * This driver does also fit for R-Car Gen2 (r8a779[0-4]) WDT. However, for SMP
192 * to work there, one also needs a RESET (RST) driver which does not exist yet
193 * due to HW issues. This needs to be solved before adding compatibles here.
194 */
195static const struct of_device_id rwdt_ids[] = {
196 { .compatible = "renesas,rcar-gen3-wdt", },
197 { /* sentinel */ }
198};
199MODULE_DEVICE_TABLE(of, rwdt_ids);
200
201static struct platform_driver rwdt_driver = {
202 .driver = {
203 .name = "renesas_wdt",
204 .of_match_table = rwdt_ids,
205 },
206 .probe = rwdt_probe,
207 .remove = rwdt_remove,
208};
209module_platform_driver(rwdt_driver);
210
211MODULE_DESCRIPTION("Renesas WDT Watchdog Driver");
212MODULE_LICENSE("GPL v2");
213MODULE_AUTHOR("Wolfram Sang <wsa@sang-engineering.com>");