1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * drivers/char/watchdog/iop_wdt.c
4 *
5 * WDT driver for Intel I/O Processors
6 * Copyright (C) 2005, Intel Corporation.
7 *
8 * Based on ixp4xx driver, Copyright 2004 (c) MontaVista, Software, Inc.
9 *
10 *	Curt E Bruns <curt.e.bruns@intel.com>
11 *	Peter Milne <peter.milne@d-tacq.com>
12 *	Dan Williams <dan.j.williams@intel.com>
13 */
14
15#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
16
17#include <linux/module.h>
18#include <linux/kernel.h>
19#include <linux/fs.h>
20#include <linux/init.h>
21#include <linux/device.h>
22#include <linux/miscdevice.h>
23#include <linux/watchdog.h>
24#include <linux/uaccess.h>
25#include <mach/hardware.h>
26
27static bool nowayout = WATCHDOG_NOWAYOUT;
28static unsigned long wdt_status;
29static unsigned long boot_status;
30static DEFINE_SPINLOCK(wdt_lock);
31
32#define WDT_IN_USE		0
33#define WDT_OK_TO_CLOSE		1
34#define WDT_ENABLED		2
35
36static unsigned long iop_watchdog_timeout(void)
37{
38	return (0xffffffffUL / get_iop_tick_rate());
39}
40
41/**
42 * wdt_supports_disable - determine if we are accessing a iop13xx watchdog
43 * or iop3xx by whether it has a disable command
44 */
45static int wdt_supports_disable(void)
46{
47	int can_disable;
48
49	if (IOP_WDTCR_EN_ARM != IOP_WDTCR_DIS_ARM)
50		can_disable = 1;
51	else
52		can_disable = 0;
53
54	return can_disable;
55}
56
57static void wdt_enable(void)
58{
59	/* Arm and enable the Timer to starting counting down from 0xFFFF.FFFF
60	 * Takes approx. 10.7s to timeout
61	 */
62	spin_lock(&wdt_lock);
63	write_wdtcr(IOP_WDTCR_EN_ARM);
64	write_wdtcr(IOP_WDTCR_EN);
65	spin_unlock(&wdt_lock);
66}
67
68/* returns 0 if the timer was successfully disabled */
69static int wdt_disable(void)
70{
71	/* Stop Counting */
72	if (wdt_supports_disable()) {
73		spin_lock(&wdt_lock);
74		write_wdtcr(IOP_WDTCR_DIS_ARM);
75		write_wdtcr(IOP_WDTCR_DIS);
76		clear_bit(WDT_ENABLED, &wdt_status);
77		spin_unlock(&wdt_lock);
78		pr_info("Disabled\n");
79		return 0;
80	} else
81		return 1;
82}
83
84static int iop_wdt_open(struct inode *inode, struct file *file)
85{
86	if (test_and_set_bit(WDT_IN_USE, &wdt_status))
87		return -EBUSY;
88
89	clear_bit(WDT_OK_TO_CLOSE, &wdt_status);
90	wdt_enable();
91	set_bit(WDT_ENABLED, &wdt_status);
92	return stream_open(inode, file);
93}
94
95static ssize_t iop_wdt_write(struct file *file, const char *data, size_t len,
96		  loff_t *ppos)
97{
98	if (len) {
99		if (!nowayout) {
100			size_t i;
101
102			clear_bit(WDT_OK_TO_CLOSE, &wdt_status);
103
104			for (i = 0; i != len; i++) {
105				char c;
106
107				if (get_user(c, data + i))
108					return -EFAULT;
109				if (c == 'V')
110					set_bit(WDT_OK_TO_CLOSE, &wdt_status);
111			}
112		}
113		wdt_enable();
114	}
115	return len;
116}
117
118static const struct watchdog_info ident = {
119	.options = WDIOF_CARDRESET | WDIOF_MAGICCLOSE | WDIOF_KEEPALIVEPING,
120	.identity = "iop watchdog",
121};
122
123static long iop_wdt_ioctl(struct file *file,
124				unsigned int cmd, unsigned long arg)
125{
126	int options;
127	int ret = -ENOTTY;
128	int __user *argp = (int __user *)arg;
129
130	switch (cmd) {
131	case WDIOC_GETSUPPORT:
132		if (copy_to_user(argp, &ident, sizeof(ident)))
133			ret = -EFAULT;
134		else
135			ret = 0;
136		break;
137
138	case WDIOC_GETSTATUS:
139		ret = put_user(0, argp);
140		break;
141
142	case WDIOC_GETBOOTSTATUS:
143		ret = put_user(boot_status, argp);
144		break;
145
146	case WDIOC_SETOPTIONS:
147		if (get_user(options, (int *)arg))
148			return -EFAULT;
149
150		if (options & WDIOS_DISABLECARD) {
151			if (!nowayout) {
152				if (wdt_disable() == 0) {
153					set_bit(WDT_OK_TO_CLOSE, &wdt_status);
154					ret = 0;
155				} else
156					ret = -ENXIO;
157			} else
158				ret = 0;
159		}
160		if (options & WDIOS_ENABLECARD) {
161			wdt_enable();
162			ret = 0;
163		}
164		break;
165
166	case WDIOC_KEEPALIVE:
167		wdt_enable();
168		ret = 0;
169		break;
170
171	case WDIOC_GETTIMEOUT:
172		ret = put_user(iop_watchdog_timeout(), argp);
173		break;
174	}
175	return ret;
176}
177
178static int iop_wdt_release(struct inode *inode, struct file *file)
179{
180	int state = 1;
181	if (test_bit(WDT_OK_TO_CLOSE, &wdt_status))
182		if (test_bit(WDT_ENABLED, &wdt_status))
183			state = wdt_disable();
184
185	/* if the timer is not disabled reload and notify that we are still
186	 * going down
187	 */
188	if (state != 0) {
189		wdt_enable();
190		pr_crit("Device closed unexpectedly - reset in %lu seconds\n",
191			iop_watchdog_timeout());
192	}
193
194	clear_bit(WDT_IN_USE, &wdt_status);
195	clear_bit(WDT_OK_TO_CLOSE, &wdt_status);
196
197	return 0;
198}
199
200static const struct file_operations iop_wdt_fops = {
201	.owner = THIS_MODULE,
202	.llseek = no_llseek,
203	.write = iop_wdt_write,
204	.unlocked_ioctl = iop_wdt_ioctl,
205	.compat_ioctl = compat_ptr_ioctl,
206	.open = iop_wdt_open,
207	.release = iop_wdt_release,
208};
209
210static struct miscdevice iop_wdt_miscdev = {
211	.minor = WATCHDOG_MINOR,
212	.name = "watchdog",
213	.fops = &iop_wdt_fops,
214};
215
216static int __init iop_wdt_init(void)
217{
218	int ret;
219
220	/* check if the reset was caused by the watchdog timer */
221	boot_status = (read_rcsr() & IOP_RCSR_WDT) ? WDIOF_CARDRESET : 0;
222
223	/* Configure Watchdog Timeout to cause an Internal Bus (IB) Reset
224	 * NOTE: An IB Reset will Reset both cores in the IOP342
225	 */
226	write_wdtsr(IOP13XX_WDTCR_IB_RESET);
227
228	/* Register after we have the device set up so we cannot race
229	   with an open */
230	ret = misc_register(&iop_wdt_miscdev);
231	if (ret == 0)
232		pr_info("timeout %lu sec\n", iop_watchdog_timeout());
233
234	return ret;
235}
236
237static void __exit iop_wdt_exit(void)
238{
239	misc_deregister(&iop_wdt_miscdev);
240}
241
242module_init(iop_wdt_init);
243module_exit(iop_wdt_exit);
244
245module_param(nowayout, bool, 0);
246MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started");
247
248MODULE_AUTHOR("Curt E Bruns <curt.e.bruns@intel.com>");
249MODULE_DESCRIPTION("iop watchdog timer driver");
250MODULE_LICENSE("GPL");
251