xref: /openbmc/linux/drivers/watchdog/ixp4xx_wdt.c (revision deedc3e1)
1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  * drivers/char/watchdog/ixp4xx_wdt.c
4  *
5  * Watchdog driver for Intel IXP4xx network processors
6  *
7  * Author: Deepak Saxena <dsaxena@plexity.net>
8  * Author: Linus Walleij <linus.walleij@linaro.org>
9  *
10  * Copyright 2004 (c) MontaVista, Software, Inc.
11  * Based on sa1100 driver, Copyright (C) 2000 Oleg Drokin <green@crimea.edu>
12  */
13 
14 #include <linux/module.h>
15 #include <linux/types.h>
16 #include <linux/kernel.h>
17 #include <linux/watchdog.h>
18 #include <linux/bits.h>
19 #include <linux/platform_device.h>
20 #include <linux/clk.h>
21 #include <linux/soc/ixp4xx/cpu.h>
22 
23 struct ixp4xx_wdt {
24 	struct watchdog_device wdd;
25 	void __iomem *base;
26 	unsigned long rate;
27 };
28 
29 /* Fallback if we do not have a clock for this */
30 #define IXP4XX_TIMER_FREQ	66666000
31 
32 /* Registers after the timer registers */
33 #define IXP4XX_OSWT_OFFSET	0x14  /* Watchdog Timer */
34 #define IXP4XX_OSWE_OFFSET	0x18  /* Watchdog Enable */
35 #define IXP4XX_OSWK_OFFSET	0x1C  /* Watchdog Key */
36 #define IXP4XX_OSST_OFFSET	0x20  /* Timer Status */
37 
38 #define IXP4XX_OSST_TIMER_WDOG_PEND	0x00000008
39 #define IXP4XX_OSST_TIMER_WARM_RESET	0x00000010
40 #define IXP4XX_WDT_KEY			0x0000482E
41 #define IXP4XX_WDT_RESET_ENABLE		0x00000001
42 #define IXP4XX_WDT_IRQ_ENABLE		0x00000002
43 #define IXP4XX_WDT_COUNT_ENABLE		0x00000004
44 
45 static inline
to_ixp4xx_wdt(struct watchdog_device * wdd)46 struct ixp4xx_wdt *to_ixp4xx_wdt(struct watchdog_device *wdd)
47 {
48 	return container_of(wdd, struct ixp4xx_wdt, wdd);
49 }
50 
ixp4xx_wdt_start(struct watchdog_device * wdd)51 static int ixp4xx_wdt_start(struct watchdog_device *wdd)
52 {
53 	struct ixp4xx_wdt *iwdt = to_ixp4xx_wdt(wdd);
54 
55 	__raw_writel(IXP4XX_WDT_KEY, iwdt->base + IXP4XX_OSWK_OFFSET);
56 	__raw_writel(0, iwdt->base + IXP4XX_OSWE_OFFSET);
57 	__raw_writel(wdd->timeout * iwdt->rate,
58 		     iwdt->base + IXP4XX_OSWT_OFFSET);
59 	__raw_writel(IXP4XX_WDT_COUNT_ENABLE | IXP4XX_WDT_RESET_ENABLE,
60 		     iwdt->base + IXP4XX_OSWE_OFFSET);
61 	__raw_writel(0, iwdt->base + IXP4XX_OSWK_OFFSET);
62 
63 	return 0;
64 }
65 
ixp4xx_wdt_stop(struct watchdog_device * wdd)66 static int ixp4xx_wdt_stop(struct watchdog_device *wdd)
67 {
68 	struct ixp4xx_wdt *iwdt = to_ixp4xx_wdt(wdd);
69 
70 	__raw_writel(IXP4XX_WDT_KEY, iwdt->base + IXP4XX_OSWK_OFFSET);
71 	__raw_writel(0, iwdt->base + IXP4XX_OSWE_OFFSET);
72 	__raw_writel(0, iwdt->base + IXP4XX_OSWK_OFFSET);
73 
74 	return 0;
75 }
76 
ixp4xx_wdt_set_timeout(struct watchdog_device * wdd,unsigned int timeout)77 static int ixp4xx_wdt_set_timeout(struct watchdog_device *wdd,
78 				  unsigned int timeout)
79 {
80 	wdd->timeout = timeout;
81 	if (watchdog_active(wdd))
82 		ixp4xx_wdt_start(wdd);
83 
84 	return 0;
85 }
86 
ixp4xx_wdt_restart(struct watchdog_device * wdd,unsigned long action,void * data)87 static int ixp4xx_wdt_restart(struct watchdog_device *wdd,
88                               unsigned long action, void *data)
89 {
90 	struct ixp4xx_wdt *iwdt = to_ixp4xx_wdt(wdd);
91 
92 	__raw_writel(IXP4XX_WDT_KEY, iwdt->base + IXP4XX_OSWK_OFFSET);
93 	__raw_writel(0, iwdt->base + IXP4XX_OSWT_OFFSET);
94 	__raw_writel(IXP4XX_WDT_COUNT_ENABLE | IXP4XX_WDT_RESET_ENABLE,
95 		     iwdt->base + IXP4XX_OSWE_OFFSET);
96 
97 	return 0;
98 }
99 
100 static const struct watchdog_ops ixp4xx_wdt_ops = {
101 	.start = ixp4xx_wdt_start,
102 	.stop = ixp4xx_wdt_stop,
103 	.set_timeout = ixp4xx_wdt_set_timeout,
104 	.restart = ixp4xx_wdt_restart,
105 	.owner = THIS_MODULE,
106 };
107 
108 /*
109  * The A0 version of the IXP422 had a bug in the watchdog making
110  * is useless, but we still need to use it to restart the system
111  * as it is the only way, so in this special case we register a
112  * "dummy" watchdog that doesn't really work, but will support
113  * the restart operation.
114  */
ixp4xx_wdt_dummy(struct watchdog_device * wdd)115 static int ixp4xx_wdt_dummy(struct watchdog_device *wdd)
116 {
117 	return 0;
118 }
119 
120 static const struct watchdog_ops ixp4xx_wdt_restart_only_ops = {
121 	.start = ixp4xx_wdt_dummy,
122 	.stop = ixp4xx_wdt_dummy,
123 	.restart = ixp4xx_wdt_restart,
124 	.owner = THIS_MODULE,
125 };
126 
127 static const struct watchdog_info ixp4xx_wdt_info = {
128 	.options = WDIOF_KEEPALIVEPING
129 		| WDIOF_MAGICCLOSE
130 		| WDIOF_SETTIMEOUT,
131 	.identity = KBUILD_MODNAME,
132 };
133 
ixp4xx_wdt_probe(struct platform_device * pdev)134 static int ixp4xx_wdt_probe(struct platform_device *pdev)
135 {
136 	static const struct watchdog_ops *iwdt_ops;
137 	struct device *dev = &pdev->dev;
138 	struct ixp4xx_wdt *iwdt;
139 	struct clk *clk;
140 	int ret;
141 
142 	if (!(read_cpuid_id() & 0xf) && !cpu_is_ixp46x()) {
143 		dev_info(dev, "Rev. A0 IXP42x CPU detected - only restart supported\n");
144 		iwdt_ops = &ixp4xx_wdt_restart_only_ops;
145 	} else {
146 		iwdt_ops = &ixp4xx_wdt_ops;
147 	}
148 
149 	iwdt = devm_kzalloc(dev, sizeof(*iwdt), GFP_KERNEL);
150 	if (!iwdt)
151 		return -ENOMEM;
152 	iwdt->base = (void __iomem *)dev->platform_data;
153 
154 	/*
155 	 * Retrieve rate from a fixed clock from the device tree if
156 	 * the parent has that, else use the default clock rate.
157 	 */
158 	clk = devm_clk_get_enabled(dev->parent, NULL);
159 	if (!IS_ERR(clk))
160 		iwdt->rate = clk_get_rate(clk);
161 
162 	if (!iwdt->rate)
163 		iwdt->rate = IXP4XX_TIMER_FREQ;
164 
165 	iwdt->wdd.info = &ixp4xx_wdt_info;
166 	iwdt->wdd.ops = iwdt_ops;
167 	iwdt->wdd.min_timeout = 1;
168 	iwdt->wdd.max_timeout = U32_MAX / iwdt->rate;
169 	iwdt->wdd.parent = dev;
170 	/* Default to 60 seconds */
171 	iwdt->wdd.timeout = 60U;
172 	watchdog_init_timeout(&iwdt->wdd, 0, dev);
173 
174 	if (__raw_readl(iwdt->base + IXP4XX_OSST_OFFSET) &
175 	    IXP4XX_OSST_TIMER_WARM_RESET)
176 		iwdt->wdd.bootstatus = WDIOF_CARDRESET;
177 
178 	ret = devm_watchdog_register_device(dev, &iwdt->wdd);
179 	if (ret)
180 		return ret;
181 
182 	dev_info(dev, "IXP4xx watchdog available\n");
183 
184 	return 0;
185 }
186 
187 static struct platform_driver ixp4xx_wdt_driver = {
188 	.probe = ixp4xx_wdt_probe,
189 	.driver = {
190 		.name   = "ixp4xx-watchdog",
191 	},
192 };
193 module_platform_driver(ixp4xx_wdt_driver);
194 
195 MODULE_AUTHOR("Deepak Saxena <dsaxena@plexity.net>");
196 MODULE_DESCRIPTION("IXP4xx Network Processor Watchdog");
197 MODULE_LICENSE("GPL");
198