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1// SPDX-License-Identifier: GPL-2.0-or-later2/*3 * GE watchdog userspace interface4 *5 * Author: Martyn Welch <martyn.welch@ge.com>6 *7 * Copyright 2008 GE Intelligent Platforms Embedded Systems, Inc.8 *9 * Based on: mv64x60_wdt.c (MV64X60 watchdog userspace interface)10 * Author: James Chapman <jchapman@katalix.com>11 */12 13/* TODO:14 * This driver does not provide support for the hardwares capability of sending15 * an interrupt at a programmable threshold.16 *17 * This driver currently can only support 1 watchdog - there are 2 in the18 * hardware that this driver supports. Thus one could be configured as a19 * process-based watchdog (via /dev/watchdog), the second (using the interrupt20 * capabilities) a kernel-based watchdog.21 */22 23#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt24 25#include <linux/kernel.h>26#include <linux/compiler.h>27#include <linux/init.h>28#include <linux/module.h>29#include <linux/miscdevice.h>30#include <linux/watchdog.h>31#include <linux/fs.h>32#include <linux/of.h>33#include <linux/of_address.h>34#include <linux/platform_device.h>35#include <linux/io.h>36#include <linux/uaccess.h>37 38#include <sysdev/fsl_soc.h>39 40/*41 * The watchdog configuration register contains a pair of 2-bit fields,42 * 1. a reload field, bits 27-26, which triggers a reload of43 * the countdown register, and44 * 2. an enable field, bits 25-24, which toggles between45 * enabling and disabling the watchdog timer.46 * Bit 31 is a read-only field which indicates whether the47 * watchdog timer is currently enabled.48 *49 * The low 24 bits contain the timer reload value.50 */51#define GEF_WDC_ENABLE_SHIFT 2452#define GEF_WDC_SERVICE_SHIFT 2653#define GEF_WDC_ENABLED_SHIFT 3154 55#define GEF_WDC_ENABLED_TRUE 156#define GEF_WDC_ENABLED_FALSE 057 58/* Flags bits */59#define GEF_WDOG_FLAG_OPENED 060 61static unsigned long wdt_flags;62static int wdt_status;63static void __iomem *gef_wdt_regs;64static int gef_wdt_timeout;65static int gef_wdt_count;66static unsigned int bus_clk;67static char expect_close;68static DEFINE_SPINLOCK(gef_wdt_spinlock);69 70static bool nowayout = WATCHDOG_NOWAYOUT;71module_param(nowayout, bool, 0);72MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="73 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");74 75 76static int gef_wdt_toggle_wdc(int enabled_predicate, int field_shift)77{78 u32 data;79 u32 enabled;80 int ret = 0;81 82 spin_lock(&gef_wdt_spinlock);83 data = ioread32be(gef_wdt_regs);84 enabled = (data >> GEF_WDC_ENABLED_SHIFT) & 1;85 86 /* only toggle the requested field if enabled state matches predicate */87 if ((enabled ^ enabled_predicate) == 0) {88 /* We write a 1, then a 2 -- to the appropriate field */89 data = (1 << field_shift) | gef_wdt_count;90 iowrite32be(data, gef_wdt_regs);91 92 data = (2 << field_shift) | gef_wdt_count;93 iowrite32be(data, gef_wdt_regs);94 ret = 1;95 }96 spin_unlock(&gef_wdt_spinlock);97 98 return ret;99}100 101static void gef_wdt_service(void)102{103 gef_wdt_toggle_wdc(GEF_WDC_ENABLED_TRUE,104 GEF_WDC_SERVICE_SHIFT);105}106 107static void gef_wdt_handler_enable(void)108{109 if (gef_wdt_toggle_wdc(GEF_WDC_ENABLED_FALSE,110 GEF_WDC_ENABLE_SHIFT)) {111 gef_wdt_service();112 pr_notice("watchdog activated\n");113 }114}115 116static void gef_wdt_handler_disable(void)117{118 if (gef_wdt_toggle_wdc(GEF_WDC_ENABLED_TRUE,119 GEF_WDC_ENABLE_SHIFT))120 pr_notice("watchdog deactivated\n");121}122 123static void gef_wdt_set_timeout(unsigned int timeout)124{125 /* maximum bus cycle count is 0xFFFFFFFF */126 if (timeout > 0xFFFFFFFF / bus_clk)127 timeout = 0xFFFFFFFF / bus_clk;128 129 /* Register only holds upper 24 bits, bit shifted into lower 24 */130 gef_wdt_count = (timeout * bus_clk) >> 8;131 gef_wdt_timeout = timeout;132}133 134 135static ssize_t gef_wdt_write(struct file *file, const char __user *data,136 size_t len, loff_t *ppos)137{138 if (len) {139 if (!nowayout) {140 size_t i;141 142 expect_close = 0;143 144 for (i = 0; i != len; i++) {145 char c;146 if (get_user(c, data + i))147 return -EFAULT;148 if (c == 'V')149 expect_close = 42;150 }151 }152 gef_wdt_service();153 }154 155 return len;156}157 158static long gef_wdt_ioctl(struct file *file, unsigned int cmd,159 unsigned long arg)160{161 int timeout;162 int options;163 void __user *argp = (void __user *)arg;164 static const struct watchdog_info info = {165 .options = WDIOF_SETTIMEOUT | WDIOF_MAGICCLOSE |166 WDIOF_KEEPALIVEPING,167 .firmware_version = 0,168 .identity = "GE watchdog",169 };170 171 switch (cmd) {172 case WDIOC_GETSUPPORT:173 if (copy_to_user(argp, &info, sizeof(info)))174 return -EFAULT;175 break;176 177 case WDIOC_GETSTATUS:178 case WDIOC_GETBOOTSTATUS:179 if (put_user(wdt_status, (int __user *)argp))180 return -EFAULT;181 wdt_status &= ~WDIOF_KEEPALIVEPING;182 break;183 184 case WDIOC_SETOPTIONS:185 if (get_user(options, (int __user *)argp))186 return -EFAULT;187 188 if (options & WDIOS_DISABLECARD)189 gef_wdt_handler_disable();190 191 if (options & WDIOS_ENABLECARD)192 gef_wdt_handler_enable();193 break;194 195 case WDIOC_KEEPALIVE:196 gef_wdt_service();197 wdt_status |= WDIOF_KEEPALIVEPING;198 break;199 200 case WDIOC_SETTIMEOUT:201 if (get_user(timeout, (int __user *)argp))202 return -EFAULT;203 gef_wdt_set_timeout(timeout);204 fallthrough;205 206 case WDIOC_GETTIMEOUT:207 if (put_user(gef_wdt_timeout, (int __user *)argp))208 return -EFAULT;209 break;210 211 default:212 return -ENOTTY;213 }214 215 return 0;216}217 218static int gef_wdt_open(struct inode *inode, struct file *file)219{220 if (test_and_set_bit(GEF_WDOG_FLAG_OPENED, &wdt_flags))221 return -EBUSY;222 223 if (nowayout)224 __module_get(THIS_MODULE);225 226 gef_wdt_handler_enable();227 228 return stream_open(inode, file);229}230 231static int gef_wdt_release(struct inode *inode, struct file *file)232{233 if (expect_close == 42)234 gef_wdt_handler_disable();235 else {236 pr_crit("unexpected close, not stopping timer!\n");237 gef_wdt_service();238 }239 expect_close = 0;240 241 clear_bit(GEF_WDOG_FLAG_OPENED, &wdt_flags);242 243 return 0;244}245 246static const struct file_operations gef_wdt_fops = {247 .owner = THIS_MODULE,248 .write = gef_wdt_write,249 .unlocked_ioctl = gef_wdt_ioctl,250 .compat_ioctl = compat_ptr_ioctl,251 .open = gef_wdt_open,252 .release = gef_wdt_release,253};254 255static struct miscdevice gef_wdt_miscdev = {256 .minor = WATCHDOG_MINOR,257 .name = "watchdog",258 .fops = &gef_wdt_fops,259};260 261 262static int gef_wdt_probe(struct platform_device *dev)263{264 int timeout = 10;265 u32 freq;266 267 bus_clk = 133; /* in MHz */268 269 freq = fsl_get_sys_freq();270 if (freq != -1)271 bus_clk = freq;272 273 /* Map devices registers into memory */274 gef_wdt_regs = of_iomap(dev->dev.of_node, 0);275 if (gef_wdt_regs == NULL)276 return -ENOMEM;277 278 gef_wdt_set_timeout(timeout);279 280 gef_wdt_handler_disable(); /* in case timer was already running */281 282 return misc_register(&gef_wdt_miscdev);283}284 285static void gef_wdt_remove(struct platform_device *dev)286{287 misc_deregister(&gef_wdt_miscdev);288 289 gef_wdt_handler_disable();290 291 iounmap(gef_wdt_regs);292}293 294static const struct of_device_id gef_wdt_ids[] = {295 {296 .compatible = "gef,fpga-wdt",297 },298 {},299};300MODULE_DEVICE_TABLE(of, gef_wdt_ids);301 302static struct platform_driver gef_wdt_driver = {303 .driver = {304 .name = "gef_wdt",305 .of_match_table = gef_wdt_ids,306 },307 .probe = gef_wdt_probe,308 .remove_new = gef_wdt_remove,309};310 311static int __init gef_wdt_init(void)312{313 pr_info("GE watchdog driver\n");314 return platform_driver_register(&gef_wdt_driver);315}316 317static void __exit gef_wdt_exit(void)318{319 platform_driver_unregister(&gef_wdt_driver);320}321 322module_init(gef_wdt_init);323module_exit(gef_wdt_exit);324 325MODULE_AUTHOR("Martyn Welch <martyn.welch@ge.com>");326MODULE_DESCRIPTION("GE watchdog driver");327MODULE_LICENSE("GPL");328MODULE_ALIAS("platform:gef_wdt");329