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	.open = iop_wdt_open,
206	.release = iop_wdt_release,
207};
208
209static struct miscdevice iop_wdt_miscdev = {
210	.minor = WATCHDOG_MINOR,
211	.name = "watchdog",
212	.fops = &iop_wdt_fops,
213};
214
215static int __init iop_wdt_init(void)
216{
217	int ret;
218
219	/* check if the reset was caused by the watchdog timer */
220	boot_status = (read_rcsr() & IOP_RCSR_WDT) ? WDIOF_CARDRESET : 0;
221
222	/* Configure Watchdog Timeout to cause an Internal Bus (IB) Reset
223	 * NOTE: An IB Reset will Reset both cores in the IOP342
224	 */
225	write_wdtsr(IOP13XX_WDTCR_IB_RESET);
226
227	/* Register after we have the device set up so we cannot race
228	   with an open */
229	ret = misc_register(&iop_wdt_miscdev);
230	if (ret == 0)
231		pr_info("timeout %lu sec\n", iop_watchdog_timeout());
232
233	return ret;
234}
235
236static void __exit iop_wdt_exit(void)
237{
238	misc_deregister(&iop_wdt_miscdev);
239}
240
241module_init(iop_wdt_init);
242module_exit(iop_wdt_exit);
243
244module_param(nowayout, bool, 0);
245MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started");
246
247MODULE_AUTHOR("Curt E Bruns <curt.e.bruns@intel.com>");
248MODULE_DESCRIPTION("iop watchdog timer driver");
249MODULE_LICENSE("GPL");