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1// SPDX-License-Identifier: GPL-2.0-or-later2/* Watchdog timer for machines with the CS5535/CS5536 companion chip3 *4 * Copyright (C) 2006-2007, Advanced Micro Devices, Inc.5 * Copyright (C) 2009 Andres Salomon <dilinger@collabora.co.uk>6 */7 8#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt9 10#include <linux/module.h>11#include <linux/moduleparam.h>12#include <linux/types.h>13#include <linux/miscdevice.h>14#include <linux/watchdog.h>15#include <linux/fs.h>16#include <linux/platform_device.h>17#include <linux/reboot.h>18#include <linux/uaccess.h>19 20#include <linux/cs5535.h>21 22#define GEODEWDT_HZ 50023#define GEODEWDT_SCALE 624#define GEODEWDT_MAX_SECONDS 13125 26#define WDT_FLAGS_OPEN 127#define WDT_FLAGS_ORPHAN 228 29#define DRV_NAME "geodewdt"30#define WATCHDOG_NAME "Geode GX/LX WDT"31#define WATCHDOG_TIMEOUT 6032 33static int timeout = WATCHDOG_TIMEOUT;34module_param(timeout, int, 0);35MODULE_PARM_DESC(timeout,36 "Watchdog timeout in seconds. 1<= timeout <=131, default="37 __MODULE_STRING(WATCHDOG_TIMEOUT) ".");38 39static bool nowayout = WATCHDOG_NOWAYOUT;40module_param(nowayout, bool, 0);41MODULE_PARM_DESC(nowayout,42 "Watchdog cannot be stopped once started (default="43 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");44 45static struct platform_device *geodewdt_platform_device;46static unsigned long wdt_flags;47static struct cs5535_mfgpt_timer *wdt_timer;48static int safe_close;49 50static void geodewdt_ping(void)51{52 /* Stop the counter */53 cs5535_mfgpt_write(wdt_timer, MFGPT_REG_SETUP, 0);54 55 /* Reset the counter */56 cs5535_mfgpt_write(wdt_timer, MFGPT_REG_COUNTER, 0);57 58 /* Enable the counter */59 cs5535_mfgpt_write(wdt_timer, MFGPT_REG_SETUP, MFGPT_SETUP_CNTEN);60}61 62static void geodewdt_disable(void)63{64 cs5535_mfgpt_write(wdt_timer, MFGPT_REG_SETUP, 0);65 cs5535_mfgpt_write(wdt_timer, MFGPT_REG_COUNTER, 0);66}67 68static int geodewdt_set_heartbeat(int val)69{70 if (val < 1 || val > GEODEWDT_MAX_SECONDS)71 return -EINVAL;72 73 cs5535_mfgpt_write(wdt_timer, MFGPT_REG_SETUP, 0);74 cs5535_mfgpt_write(wdt_timer, MFGPT_REG_CMP2, val * GEODEWDT_HZ);75 cs5535_mfgpt_write(wdt_timer, MFGPT_REG_COUNTER, 0);76 cs5535_mfgpt_write(wdt_timer, MFGPT_REG_SETUP, MFGPT_SETUP_CNTEN);77 78 timeout = val;79 return 0;80}81 82static int geodewdt_open(struct inode *inode, struct file *file)83{84 if (test_and_set_bit(WDT_FLAGS_OPEN, &wdt_flags))85 return -EBUSY;86 87 if (!test_and_clear_bit(WDT_FLAGS_ORPHAN, &wdt_flags))88 __module_get(THIS_MODULE);89 90 geodewdt_ping();91 return stream_open(inode, file);92}93 94static int geodewdt_release(struct inode *inode, struct file *file)95{96 if (safe_close) {97 geodewdt_disable();98 module_put(THIS_MODULE);99 } else {100 pr_crit("Unexpected close - watchdog is not stopping\n");101 geodewdt_ping();102 103 set_bit(WDT_FLAGS_ORPHAN, &wdt_flags);104 }105 106 clear_bit(WDT_FLAGS_OPEN, &wdt_flags);107 safe_close = 0;108 return 0;109}110 111static ssize_t geodewdt_write(struct file *file, const char __user *data,112 size_t len, loff_t *ppos)113{114 if (len) {115 if (!nowayout) {116 size_t i;117 safe_close = 0;118 119 for (i = 0; i != len; i++) {120 char c;121 122 if (get_user(c, data + i))123 return -EFAULT;124 125 if (c == 'V')126 safe_close = 1;127 }128 }129 130 geodewdt_ping();131 }132 return len;133}134 135static long geodewdt_ioctl(struct file *file, unsigned int cmd,136 unsigned long arg)137{138 void __user *argp = (void __user *)arg;139 int __user *p = argp;140 int interval;141 142 static const struct watchdog_info ident = {143 .options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING144 | WDIOF_MAGICCLOSE,145 .firmware_version = 1,146 .identity = WATCHDOG_NAME,147 };148 149 switch (cmd) {150 case WDIOC_GETSUPPORT:151 return copy_to_user(argp, &ident,152 sizeof(ident)) ? -EFAULT : 0;153 case WDIOC_GETSTATUS:154 case WDIOC_GETBOOTSTATUS:155 return put_user(0, p);156 157 case WDIOC_SETOPTIONS:158 {159 int options, ret = -EINVAL;160 161 if (get_user(options, p))162 return -EFAULT;163 164 if (options & WDIOS_DISABLECARD) {165 geodewdt_disable();166 ret = 0;167 }168 169 if (options & WDIOS_ENABLECARD) {170 geodewdt_ping();171 ret = 0;172 }173 174 return ret;175 }176 case WDIOC_KEEPALIVE:177 geodewdt_ping();178 return 0;179 180 case WDIOC_SETTIMEOUT:181 if (get_user(interval, p))182 return -EFAULT;183 184 if (geodewdt_set_heartbeat(interval))185 return -EINVAL;186 fallthrough;187 case WDIOC_GETTIMEOUT:188 return put_user(timeout, p);189 190 default:191 return -ENOTTY;192 }193 194 return 0;195}196 197static const struct file_operations geodewdt_fops = {198 .owner = THIS_MODULE,199 .write = geodewdt_write,200 .unlocked_ioctl = geodewdt_ioctl,201 .compat_ioctl = compat_ptr_ioctl,202 .open = geodewdt_open,203 .release = geodewdt_release,204};205 206static struct miscdevice geodewdt_miscdev = {207 .minor = WATCHDOG_MINOR,208 .name = "watchdog",209 .fops = &geodewdt_fops,210};211 212static int __init geodewdt_probe(struct platform_device *dev)213{214 int ret;215 216 wdt_timer = cs5535_mfgpt_alloc_timer(MFGPT_TIMER_ANY, MFGPT_DOMAIN_WORKING);217 if (!wdt_timer) {218 pr_err("No timers were available\n");219 return -ENODEV;220 }221 222 /* Set up the timer */223 224 cs5535_mfgpt_write(wdt_timer, MFGPT_REG_SETUP,225 GEODEWDT_SCALE | (3 << 8));226 227 /* Set up comparator 2 to reset when the event fires */228 cs5535_mfgpt_toggle_event(wdt_timer, MFGPT_CMP2, MFGPT_EVENT_RESET, 1);229 230 /* Set up the initial timeout */231 232 cs5535_mfgpt_write(wdt_timer, MFGPT_REG_CMP2,233 timeout * GEODEWDT_HZ);234 235 ret = misc_register(&geodewdt_miscdev);236 237 return ret;238}239 240static void geodewdt_remove(struct platform_device *dev)241{242 misc_deregister(&geodewdt_miscdev);243}244 245static void geodewdt_shutdown(struct platform_device *dev)246{247 geodewdt_disable();248}249 250static struct platform_driver geodewdt_driver = {251 .remove_new = geodewdt_remove,252 .shutdown = geodewdt_shutdown,253 .driver = {254 .name = DRV_NAME,255 },256};257 258static int __init geodewdt_init(void)259{260 int ret;261 262 geodewdt_platform_device = platform_device_register_simple(DRV_NAME,263 -1, NULL, 0);264 if (IS_ERR(geodewdt_platform_device))265 return PTR_ERR(geodewdt_platform_device);266 267 ret = platform_driver_probe(&geodewdt_driver, geodewdt_probe);268 if (ret)269 goto err;270 271 return 0;272err:273 platform_device_unregister(geodewdt_platform_device);274 return ret;275}276 277static void __exit geodewdt_exit(void)278{279 platform_device_unregister(geodewdt_platform_device);280 platform_driver_unregister(&geodewdt_driver);281}282 283module_init(geodewdt_init);284module_exit(geodewdt_exit);285 286MODULE_AUTHOR("Advanced Micro Devices, Inc");287MODULE_DESCRIPTION("Geode GX/LX Watchdog Driver");288MODULE_LICENSE("GPL");289