1 // SPDX-License-Identifier: GPL-2.0
2 /*
3  * drivers/char/watchdog/pnx4008_wdt.c
4  *
5  * Watchdog driver for PNX4008 board
6  *
7  * Authors: Dmitry Chigirev <source@mvista.com>,
8  *	    Vitaly Wool <vitalywool@gmail.com>
9  * Based on sa1100 driver,
10  * Copyright (C) 2000 Oleg Drokin <green@crimea.edu>
11  *
12  * 2005-2006 (c) MontaVista Software, Inc.
13  *
14  * (C) 2012 Wolfram Sang, Pengutronix
15  */
16 
17 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
18 
19 #include <linux/module.h>
20 #include <linux/moduleparam.h>
21 #include <linux/types.h>
22 #include <linux/kernel.h>
23 #include <linux/watchdog.h>
24 #include <linux/platform_device.h>
25 #include <linux/clk.h>
26 #include <linux/spinlock.h>
27 #include <linux/io.h>
28 #include <linux/slab.h>
29 #include <linux/err.h>
30 #include <linux/of.h>
31 #include <linux/delay.h>
32 #include <linux/reboot.h>
33 
34 /* WatchDog Timer - Chapter 23 Page 207 */
35 
36 #define DEFAULT_HEARTBEAT 19
37 #define MAX_HEARTBEAT     60
38 
39 /* Watchdog timer register set definition */
40 #define WDTIM_INT(p)     ((p) + 0x0)
41 #define WDTIM_CTRL(p)    ((p) + 0x4)
42 #define WDTIM_COUNTER(p) ((p) + 0x8)
43 #define WDTIM_MCTRL(p)   ((p) + 0xC)
44 #define WDTIM_MATCH0(p)  ((p) + 0x10)
45 #define WDTIM_EMR(p)     ((p) + 0x14)
46 #define WDTIM_PULSE(p)   ((p) + 0x18)
47 #define WDTIM_RES(p)     ((p) + 0x1C)
48 
49 /* WDTIM_INT bit definitions */
50 #define MATCH_INT      1
51 
52 /* WDTIM_CTRL bit definitions */
53 #define COUNT_ENAB     1
54 #define RESET_COUNT    (1 << 1)
55 #define DEBUG_EN       (1 << 2)
56 
57 /* WDTIM_MCTRL bit definitions */
58 #define MR0_INT        1
59 #undef  RESET_COUNT0
60 #define RESET_COUNT0   (1 << 2)
61 #define STOP_COUNT0    (1 << 2)
62 #define M_RES1         (1 << 3)
63 #define M_RES2         (1 << 4)
64 #define RESFRC1        (1 << 5)
65 #define RESFRC2        (1 << 6)
66 
67 /* WDTIM_EMR bit definitions */
68 #define EXT_MATCH0      1
69 #define MATCH_OUTPUT_HIGH (2 << 4)	/*a MATCH_CTRL setting */
70 
71 /* WDTIM_RES bit definitions */
72 #define WDOG_RESET      1	/* read only */
73 
74 #define WDOG_COUNTER_RATE 13000000	/*the counter clock is 13 MHz fixed */
75 
76 static bool nowayout = WATCHDOG_NOWAYOUT;
77 static unsigned int heartbeat;
78 
79 static DEFINE_SPINLOCK(io_lock);
80 static void __iomem	*wdt_base;
81 static struct clk	*wdt_clk;
82 
pnx4008_wdt_start(struct watchdog_device * wdd)83 static int pnx4008_wdt_start(struct watchdog_device *wdd)
84 {
85 	spin_lock(&io_lock);
86 
87 	/* stop counter, initiate counter reset */
88 	writel(RESET_COUNT, WDTIM_CTRL(wdt_base));
89 	/*wait for reset to complete. 100% guarantee event */
90 	while (readl(WDTIM_COUNTER(wdt_base)))
91 		cpu_relax();
92 	/* internal and external reset, stop after that */
93 	writel(M_RES2 | STOP_COUNT0 | RESET_COUNT0, WDTIM_MCTRL(wdt_base));
94 	/* configure match output */
95 	writel(MATCH_OUTPUT_HIGH, WDTIM_EMR(wdt_base));
96 	/* clear interrupt, just in case */
97 	writel(MATCH_INT, WDTIM_INT(wdt_base));
98 	/* the longest pulse period 65541/(13*10^6) seconds ~ 5 ms. */
99 	writel(0xFFFF, WDTIM_PULSE(wdt_base));
100 	writel(wdd->timeout * WDOG_COUNTER_RATE, WDTIM_MATCH0(wdt_base));
101 	/*enable counter, stop when debugger active */
102 	writel(COUNT_ENAB | DEBUG_EN, WDTIM_CTRL(wdt_base));
103 
104 	spin_unlock(&io_lock);
105 	return 0;
106 }
107 
pnx4008_wdt_stop(struct watchdog_device * wdd)108 static int pnx4008_wdt_stop(struct watchdog_device *wdd)
109 {
110 	spin_lock(&io_lock);
111 
112 	writel(0, WDTIM_CTRL(wdt_base));	/*stop counter */
113 
114 	spin_unlock(&io_lock);
115 	return 0;
116 }
117 
pnx4008_wdt_set_timeout(struct watchdog_device * wdd,unsigned int new_timeout)118 static int pnx4008_wdt_set_timeout(struct watchdog_device *wdd,
119 				    unsigned int new_timeout)
120 {
121 	wdd->timeout = new_timeout;
122 	return 0;
123 }
124 
pnx4008_restart_handler(struct watchdog_device * wdd,unsigned long mode,void * cmd)125 static int pnx4008_restart_handler(struct watchdog_device *wdd,
126 				   unsigned long mode, void *cmd)
127 {
128 	const char *boot_cmd = cmd;
129 
130 	/*
131 	 * Verify if a "cmd" passed from the userspace program rebooting
132 	 * the system; if available, handle it.
133 	 * - For details, see the 'reboot' syscall in kernel/reboot.c
134 	 * - If the received "cmd" is not supported, use the default mode.
135 	 */
136 	if (boot_cmd) {
137 		if (boot_cmd[0] == 'h')
138 			mode = REBOOT_HARD;
139 		else if (boot_cmd[0] == 's')
140 			mode = REBOOT_SOFT;
141 	}
142 
143 	if (mode == REBOOT_SOFT) {
144 		/* Force match output active */
145 		writel(EXT_MATCH0, WDTIM_EMR(wdt_base));
146 		/* Internal reset on match output (RESOUT_N not asserted) */
147 		writel(M_RES1, WDTIM_MCTRL(wdt_base));
148 	} else {
149 		/* Instant assert of RESETOUT_N with pulse length 1mS */
150 		writel(13000, WDTIM_PULSE(wdt_base));
151 		writel(M_RES2 | RESFRC1 | RESFRC2, WDTIM_MCTRL(wdt_base));
152 	}
153 
154 	/* Wait for watchdog to reset system */
155 	mdelay(1000);
156 
157 	return NOTIFY_DONE;
158 }
159 
160 static const struct watchdog_info pnx4008_wdt_ident = {
161 	.options = WDIOF_CARDRESET | WDIOF_MAGICCLOSE |
162 	    WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING,
163 	.identity = "PNX4008 Watchdog",
164 };
165 
166 static const struct watchdog_ops pnx4008_wdt_ops = {
167 	.owner = THIS_MODULE,
168 	.start = pnx4008_wdt_start,
169 	.stop = pnx4008_wdt_stop,
170 	.set_timeout = pnx4008_wdt_set_timeout,
171 	.restart = pnx4008_restart_handler,
172 };
173 
174 static struct watchdog_device pnx4008_wdd = {
175 	.info = &pnx4008_wdt_ident,
176 	.ops = &pnx4008_wdt_ops,
177 	.timeout = DEFAULT_HEARTBEAT,
178 	.min_timeout = 1,
179 	.max_timeout = MAX_HEARTBEAT,
180 };
181 
pnx4008_clk_disable_unprepare(void * data)182 static void pnx4008_clk_disable_unprepare(void *data)
183 {
184 	clk_disable_unprepare(data);
185 }
186 
pnx4008_wdt_probe(struct platform_device * pdev)187 static int pnx4008_wdt_probe(struct platform_device *pdev)
188 {
189 	struct device *dev = &pdev->dev;
190 	int ret = 0;
191 
192 	watchdog_init_timeout(&pnx4008_wdd, heartbeat, dev);
193 
194 	wdt_base = devm_platform_ioremap_resource(pdev, 0);
195 	if (IS_ERR(wdt_base))
196 		return PTR_ERR(wdt_base);
197 
198 	wdt_clk = devm_clk_get(dev, NULL);
199 	if (IS_ERR(wdt_clk))
200 		return PTR_ERR(wdt_clk);
201 
202 	ret = clk_prepare_enable(wdt_clk);
203 	if (ret)
204 		return ret;
205 	ret = devm_add_action_or_reset(dev, pnx4008_clk_disable_unprepare,
206 				       wdt_clk);
207 	if (ret)
208 		return ret;
209 
210 	pnx4008_wdd.bootstatus = (readl(WDTIM_RES(wdt_base)) & WDOG_RESET) ?
211 			WDIOF_CARDRESET : 0;
212 	pnx4008_wdd.parent = dev;
213 	watchdog_set_nowayout(&pnx4008_wdd, nowayout);
214 	watchdog_set_restart_priority(&pnx4008_wdd, 128);
215 
216 	if (readl(WDTIM_CTRL(wdt_base)) & COUNT_ENAB)
217 		set_bit(WDOG_HW_RUNNING, &pnx4008_wdd.status);
218 
219 	ret = devm_watchdog_register_device(dev, &pnx4008_wdd);
220 	if (ret < 0)
221 		return ret;
222 
223 	dev_info(dev, "heartbeat %d sec\n", pnx4008_wdd.timeout);
224 
225 	return 0;
226 }
227 
228 #ifdef CONFIG_OF
229 static const struct of_device_id pnx4008_wdt_match[] = {
230 	{ .compatible = "nxp,pnx4008-wdt" },
231 	{ }
232 };
233 MODULE_DEVICE_TABLE(of, pnx4008_wdt_match);
234 #endif
235 
236 static struct platform_driver platform_wdt_driver = {
237 	.driver = {
238 		.name = "pnx4008-watchdog",
239 		.of_match_table = of_match_ptr(pnx4008_wdt_match),
240 	},
241 	.probe = pnx4008_wdt_probe,
242 };
243 
244 module_platform_driver(platform_wdt_driver);
245 
246 MODULE_AUTHOR("MontaVista Software, Inc. <source@mvista.com>");
247 MODULE_AUTHOR("Wolfram Sang <kernel@pengutronix.de>");
248 MODULE_DESCRIPTION("PNX4008 Watchdog Driver");
249 
250 module_param(heartbeat, uint, 0);
251 MODULE_PARM_DESC(heartbeat,
252 		 "Watchdog heartbeat period in seconds from 1 to "
253 		 __MODULE_STRING(MAX_HEARTBEAT) ", default "
254 		 __MODULE_STRING(DEFAULT_HEARTBEAT));
255 
256 module_param(nowayout, bool, 0);
257 MODULE_PARM_DESC(nowayout,
258 		 "Set to 1 to keep watchdog running after device release");
259 
260 MODULE_LICENSE("GPL");
261 MODULE_ALIAS("platform:pnx4008-watchdog");
262