1 /* 2 * txx9wdt: A Hardware Watchdog Driver for TXx9 SoCs 3 * 4 * Copyright (C) 2007 Atsushi Nemoto <anemo@mba.ocn.ne.jp> 5 * 6 * This program is free software; you can redistribute it and/or modify 7 * it under the terms of the GNU General Public License version 2 as 8 * published by the Free Software Foundation. 9 */ 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/reboot.h> 17 #include <linux/init.h> 18 #include <linux/uaccess.h> 19 #include <linux/platform_device.h> 20 #include <linux/clk.h> 21 #include <linux/err.h> 22 #include <linux/io.h> 23 #include <asm/txx9tmr.h> 24 25 #define TIMER_MARGIN 60 /* Default is 60 seconds */ 26 27 static int timeout = TIMER_MARGIN; /* in seconds */ 28 module_param(timeout, int, 0); 29 MODULE_PARM_DESC(timeout, 30 "Watchdog timeout in seconds. " 31 "(0<timeout<((2^" __MODULE_STRING(TXX9_TIMER_BITS) ")/(IMCLK/256)), " 32 "default=" __MODULE_STRING(TIMER_MARGIN) ")"); 33 34 static int nowayout = WATCHDOG_NOWAYOUT; 35 module_param(nowayout, int, 0); 36 MODULE_PARM_DESC(nowayout, 37 "Watchdog cannot be stopped once started " 38 "(default=" __MODULE_STRING(WATCHDOG_NOWAYOUT) ")"); 39 40 #define WD_TIMER_CCD 7 /* 1/256 */ 41 #define WD_TIMER_CLK (clk_get_rate(txx9_imclk) / (2 << WD_TIMER_CCD)) 42 #define WD_MAX_TIMEOUT ((0xffffffff >> (32 - TXX9_TIMER_BITS)) / WD_TIMER_CLK) 43 44 static unsigned long txx9wdt_alive; 45 static int expect_close; 46 static struct txx9_tmr_reg __iomem *txx9wdt_reg; 47 static struct clk *txx9_imclk; 48 static DEFINE_SPINLOCK(txx9_lock); 49 50 static void txx9wdt_ping(void) 51 { 52 spin_lock(&txx9_lock); 53 __raw_writel(TXx9_TMWTMR_TWIE | TXx9_TMWTMR_TWC, &txx9wdt_reg->wtmr); 54 spin_unlock(&txx9_lock); 55 } 56 57 static void txx9wdt_start(void) 58 { 59 spin_lock(&txx9_lock); 60 __raw_writel(WD_TIMER_CLK * timeout, &txx9wdt_reg->cpra); 61 __raw_writel(WD_TIMER_CCD, &txx9wdt_reg->ccdr); 62 __raw_writel(0, &txx9wdt_reg->tisr); /* clear pending interrupt */ 63 __raw_writel(TXx9_TMTCR_TCE | TXx9_TMTCR_CCDE | TXx9_TMTCR_TMODE_WDOG, 64 &txx9wdt_reg->tcr); 65 __raw_writel(TXx9_TMWTMR_TWIE | TXx9_TMWTMR_TWC, &txx9wdt_reg->wtmr); 66 spin_unlock(&txx9_lock); 67 } 68 69 static void txx9wdt_stop(void) 70 { 71 spin_lock(&txx9_lock); 72 __raw_writel(TXx9_TMWTMR_WDIS, &txx9wdt_reg->wtmr); 73 __raw_writel(__raw_readl(&txx9wdt_reg->tcr) & ~TXx9_TMTCR_TCE, 74 &txx9wdt_reg->tcr); 75 spin_unlock(&txx9_lock); 76 } 77 78 static int txx9wdt_open(struct inode *inode, struct file *file) 79 { 80 if (test_and_set_bit(0, &txx9wdt_alive)) 81 return -EBUSY; 82 83 if (__raw_readl(&txx9wdt_reg->tcr) & TXx9_TMTCR_TCE) { 84 clear_bit(0, &txx9wdt_alive); 85 return -EBUSY; 86 } 87 88 if (nowayout) 89 __module_get(THIS_MODULE); 90 91 txx9wdt_start(); 92 return nonseekable_open(inode, file); 93 } 94 95 static int txx9wdt_release(struct inode *inode, struct file *file) 96 { 97 if (expect_close) 98 txx9wdt_stop(); 99 else { 100 printk(KERN_CRIT "txx9wdt: " 101 "Unexpected close, not stopping watchdog!\n"); 102 txx9wdt_ping(); 103 } 104 clear_bit(0, &txx9wdt_alive); 105 expect_close = 0; 106 return 0; 107 } 108 109 static ssize_t txx9wdt_write(struct file *file, const char __user *data, 110 size_t len, loff_t *ppos) 111 { 112 if (len) { 113 if (!nowayout) { 114 size_t i; 115 116 expect_close = 0; 117 for (i = 0; i != len; i++) { 118 char c; 119 if (get_user(c, data + i)) 120 return -EFAULT; 121 if (c == 'V') 122 expect_close = 1; 123 } 124 } 125 txx9wdt_ping(); 126 } 127 return len; 128 } 129 130 static long txx9wdt_ioctl(struct file *file, unsigned int cmd, 131 unsigned long arg) 132 { 133 void __user *argp = (void __user *)arg; 134 int __user *p = argp; 135 int new_timeout; 136 static const struct watchdog_info ident = { 137 .options = WDIOF_SETTIMEOUT | 138 WDIOF_KEEPALIVEPING | 139 WDIOF_MAGICCLOSE, 140 .firmware_version = 0, 141 .identity = "Hardware Watchdog for TXx9", 142 }; 143 144 switch (cmd) { 145 case WDIOC_GETSUPPORT: 146 return copy_to_user(argp, &ident, sizeof(ident)) ? -EFAULT : 0; 147 case WDIOC_GETSTATUS: 148 case WDIOC_GETBOOTSTATUS: 149 return put_user(0, p); 150 case WDIOC_KEEPALIVE: 151 txx9wdt_ping(); 152 return 0; 153 case WDIOC_SETTIMEOUT: 154 if (get_user(new_timeout, p)) 155 return -EFAULT; 156 if (new_timeout < 1 || new_timeout > WD_MAX_TIMEOUT) 157 return -EINVAL; 158 timeout = new_timeout; 159 txx9wdt_stop(); 160 txx9wdt_start(); 161 /* Fall */ 162 case WDIOC_GETTIMEOUT: 163 return put_user(timeout, p); 164 default: 165 return -ENOTTY; 166 } 167 } 168 169 static int txx9wdt_notify_sys(struct notifier_block *this, unsigned long code, 170 void *unused) 171 { 172 if (code == SYS_DOWN || code == SYS_HALT) 173 txx9wdt_stop(); 174 return NOTIFY_DONE; 175 } 176 177 static const struct file_operations txx9wdt_fops = { 178 .owner = THIS_MODULE, 179 .llseek = no_llseek, 180 .write = txx9wdt_write, 181 .unlocked_ioctl = txx9wdt_ioctl, 182 .open = txx9wdt_open, 183 .release = txx9wdt_release, 184 }; 185 186 static struct miscdevice txx9wdt_miscdev = { 187 .minor = WATCHDOG_MINOR, 188 .name = "watchdog", 189 .fops = &txx9wdt_fops, 190 }; 191 192 static struct notifier_block txx9wdt_notifier = { 193 .notifier_call = txx9wdt_notify_sys, 194 }; 195 196 static int __init txx9wdt_probe(struct platform_device *dev) 197 { 198 struct resource *res; 199 int ret; 200 201 txx9_imclk = clk_get(NULL, "imbus_clk"); 202 if (IS_ERR(txx9_imclk)) { 203 ret = PTR_ERR(txx9_imclk); 204 txx9_imclk = NULL; 205 goto exit; 206 } 207 ret = clk_enable(txx9_imclk); 208 if (ret) { 209 clk_put(txx9_imclk); 210 txx9_imclk = NULL; 211 goto exit; 212 } 213 214 res = platform_get_resource(dev, IORESOURCE_MEM, 0); 215 if (!res) 216 goto exit_busy; 217 if (!devm_request_mem_region(&dev->dev, res->start, resource_size(res), 218 "txx9wdt")) 219 goto exit_busy; 220 txx9wdt_reg = devm_ioremap(&dev->dev, res->start, resource_size(res)); 221 if (!txx9wdt_reg) 222 goto exit_busy; 223 224 ret = register_reboot_notifier(&txx9wdt_notifier); 225 if (ret) 226 goto exit; 227 228 ret = misc_register(&txx9wdt_miscdev); 229 if (ret) { 230 unregister_reboot_notifier(&txx9wdt_notifier); 231 goto exit; 232 } 233 234 printk(KERN_INFO "Hardware Watchdog Timer for TXx9: " 235 "timeout=%d sec (max %ld) (nowayout= %d)\n", 236 timeout, WD_MAX_TIMEOUT, nowayout); 237 238 return 0; 239 exit_busy: 240 ret = -EBUSY; 241 exit: 242 if (txx9_imclk) { 243 clk_disable(txx9_imclk); 244 clk_put(txx9_imclk); 245 } 246 return ret; 247 } 248 249 static int __exit txx9wdt_remove(struct platform_device *dev) 250 { 251 misc_deregister(&txx9wdt_miscdev); 252 unregister_reboot_notifier(&txx9wdt_notifier); 253 clk_disable(txx9_imclk); 254 clk_put(txx9_imclk); 255 return 0; 256 } 257 258 static struct platform_driver txx9wdt_driver = { 259 .remove = __exit_p(txx9wdt_remove), 260 .driver = { 261 .name = "txx9wdt", 262 .owner = THIS_MODULE, 263 }, 264 }; 265 266 static int __init watchdog_init(void) 267 { 268 return platform_driver_probe(&txx9wdt_driver, txx9wdt_probe); 269 } 270 271 static void __exit watchdog_exit(void) 272 { 273 platform_driver_unregister(&txx9wdt_driver); 274 } 275 276 module_init(watchdog_init); 277 module_exit(watchdog_exit); 278 279 MODULE_DESCRIPTION("TXx9 Watchdog Driver"); 280 MODULE_LICENSE("GPL"); 281 MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR); 282 MODULE_ALIAS("platform:txx9wdt"); 283