1 /* 2 * drivers/char/watchdog/davinci_wdt.c 3 * 4 * Watchdog driver for DaVinci DM644x/DM646x processors 5 * 6 * Copyright (C) 2006 Texas Instruments. 7 * 8 * 2007 (c) MontaVista Software, Inc. This file is licensed under 9 * the terms of the GNU General Public License version 2. This program 10 * is licensed "as is" without any warranty of any kind, whether express 11 * or implied. 12 */ 13 14 #include <linux/module.h> 15 #include <linux/moduleparam.h> 16 #include <linux/types.h> 17 #include <linux/kernel.h> 18 #include <linux/fs.h> 19 #include <linux/miscdevice.h> 20 #include <linux/watchdog.h> 21 #include <linux/init.h> 22 #include <linux/bitops.h> 23 #include <linux/platform_device.h> 24 #include <linux/spinlock.h> 25 #include <linux/uaccess.h> 26 #include <linux/io.h> 27 #include <mach/hardware.h> 28 29 #define MODULE_NAME "DAVINCI-WDT: " 30 31 #define DEFAULT_HEARTBEAT 60 32 #define MAX_HEARTBEAT 600 /* really the max margin is 264/27MHz*/ 33 34 /* Timer register set definition */ 35 #define PID12 (0x0) 36 #define EMUMGT (0x4) 37 #define TIM12 (0x10) 38 #define TIM34 (0x14) 39 #define PRD12 (0x18) 40 #define PRD34 (0x1C) 41 #define TCR (0x20) 42 #define TGCR (0x24) 43 #define WDTCR (0x28) 44 45 /* TCR bit definitions */ 46 #define ENAMODE12_DISABLED (0 << 6) 47 #define ENAMODE12_ONESHOT (1 << 6) 48 #define ENAMODE12_PERIODIC (2 << 6) 49 50 /* TGCR bit definitions */ 51 #define TIM12RS_UNRESET (1 << 0) 52 #define TIM34RS_UNRESET (1 << 1) 53 #define TIMMODE_64BIT_WDOG (2 << 2) 54 55 /* WDTCR bit definitions */ 56 #define WDEN (1 << 14) 57 #define WDFLAG (1 << 15) 58 #define WDKEY_SEQ0 (0xa5c6 << 16) 59 #define WDKEY_SEQ1 (0xda7e << 16) 60 61 static int heartbeat = DEFAULT_HEARTBEAT; 62 63 static DEFINE_SPINLOCK(io_lock); 64 static unsigned long wdt_status; 65 #define WDT_IN_USE 0 66 #define WDT_OK_TO_CLOSE 1 67 #define WDT_REGION_INITED 2 68 #define WDT_DEVICE_INITED 3 69 70 static struct resource *wdt_mem; 71 static void __iomem *wdt_base; 72 73 static void wdt_service(void) 74 { 75 spin_lock(&io_lock); 76 77 /* put watchdog in service state */ 78 davinci_writel(WDKEY_SEQ0, wdt_base + WDTCR); 79 /* put watchdog in active state */ 80 davinci_writel(WDKEY_SEQ1, wdt_base + WDTCR); 81 82 spin_unlock(&io_lock); 83 } 84 85 static void wdt_enable(void) 86 { 87 u32 tgcr; 88 u32 timer_margin; 89 90 spin_lock(&io_lock); 91 92 /* disable, internal clock source */ 93 davinci_writel(0, wdt_base + TCR); 94 /* reset timer, set mode to 64-bit watchdog, and unreset */ 95 davinci_writel(0, wdt_base + TGCR); 96 tgcr = TIMMODE_64BIT_WDOG | TIM12RS_UNRESET | TIM34RS_UNRESET; 97 davinci_writel(tgcr, wdt_base + TGCR); 98 /* clear counter regs */ 99 davinci_writel(0, wdt_base + TIM12); 100 davinci_writel(0, wdt_base + TIM34); 101 /* set timeout period */ 102 timer_margin = (((u64)heartbeat * CLOCK_TICK_RATE) & 0xffffffff); 103 davinci_writel(timer_margin, wdt_base + PRD12); 104 timer_margin = (((u64)heartbeat * CLOCK_TICK_RATE) >> 32); 105 davinci_writel(timer_margin, wdt_base + PRD34); 106 /* enable run continuously */ 107 davinci_writel(ENAMODE12_PERIODIC, wdt_base + TCR); 108 /* Once the WDT is in pre-active state write to 109 * TIM12, TIM34, PRD12, PRD34, TCR, TGCR, WDTCR are 110 * write protected (except for the WDKEY field) 111 */ 112 /* put watchdog in pre-active state */ 113 davinci_writel(WDKEY_SEQ0 | WDEN, wdt_base + WDTCR); 114 /* put watchdog in active state */ 115 davinci_writel(WDKEY_SEQ1 | WDEN, wdt_base + WDTCR); 116 117 spin_unlock(&io_lock); 118 } 119 120 static int davinci_wdt_open(struct inode *inode, struct file *file) 121 { 122 if (test_and_set_bit(WDT_IN_USE, &wdt_status)) 123 return -EBUSY; 124 125 wdt_enable(); 126 127 return nonseekable_open(inode, file); 128 } 129 130 static ssize_t 131 davinci_wdt_write(struct file *file, const char *data, size_t len, 132 loff_t *ppos) 133 { 134 if (len) 135 wdt_service(); 136 137 return len; 138 } 139 140 static struct watchdog_info ident = { 141 .options = WDIOF_KEEPALIVEPING, 142 .identity = "DaVinci Watchdog", 143 }; 144 145 static long davinci_wdt_ioctl(struct file *file, 146 unsigned int cmd, unsigned long arg) 147 { 148 int ret = -ENOTTY; 149 150 switch (cmd) { 151 case WDIOC_GETSUPPORT: 152 ret = copy_to_user((struct watchdog_info *)arg, &ident, 153 sizeof(ident)) ? -EFAULT : 0; 154 break; 155 156 case WDIOC_GETSTATUS: 157 case WDIOC_GETBOOTSTATUS: 158 ret = put_user(0, (int *)arg); 159 break; 160 161 case WDIOC_KEEPALIVE: 162 wdt_service(); 163 ret = 0; 164 break; 165 166 case WDIOC_GETTIMEOUT: 167 ret = put_user(heartbeat, (int *)arg); 168 break; 169 } 170 return ret; 171 } 172 173 static int davinci_wdt_release(struct inode *inode, struct file *file) 174 { 175 wdt_service(); 176 clear_bit(WDT_IN_USE, &wdt_status); 177 178 return 0; 179 } 180 181 static const struct file_operations davinci_wdt_fops = { 182 .owner = THIS_MODULE, 183 .llseek = no_llseek, 184 .write = davinci_wdt_write, 185 .unlocked_ioctl = davinci_wdt_ioctl, 186 .open = davinci_wdt_open, 187 .release = davinci_wdt_release, 188 }; 189 190 static struct miscdevice davinci_wdt_miscdev = { 191 .minor = WATCHDOG_MINOR, 192 .name = "watchdog", 193 .fops = &davinci_wdt_fops, 194 }; 195 196 static int davinci_wdt_probe(struct platform_device *pdev) 197 { 198 int ret = 0, size; 199 struct resource *res; 200 201 if (heartbeat < 1 || heartbeat > MAX_HEARTBEAT) 202 heartbeat = DEFAULT_HEARTBEAT; 203 204 printk(KERN_INFO MODULE_NAME 205 "DaVinci Watchdog Timer: heartbeat %d sec\n", heartbeat); 206 207 res = platform_get_resource(pdev, IORESOURCE_MEM, 0); 208 if (res == NULL) { 209 printk(KERN_INFO MODULE_NAME 210 "failed to get memory region resource\n"); 211 return -ENOENT; 212 } 213 214 size = res->end - res->start + 1; 215 wdt_mem = request_mem_region(res->start, size, pdev->name); 216 217 if (wdt_mem == NULL) { 218 printk(KERN_INFO MODULE_NAME "failed to get memory region\n"); 219 return -ENOENT; 220 } 221 wdt_base = (void __iomem *)(res->start); 222 223 ret = misc_register(&davinci_wdt_miscdev); 224 if (ret < 0) { 225 printk(KERN_ERR MODULE_NAME "cannot register misc device\n"); 226 release_resource(wdt_mem); 227 kfree(wdt_mem); 228 } else { 229 set_bit(WDT_DEVICE_INITED, &wdt_status); 230 } 231 232 return ret; 233 } 234 235 static int davinci_wdt_remove(struct platform_device *pdev) 236 { 237 misc_deregister(&davinci_wdt_miscdev); 238 if (wdt_mem) { 239 release_resource(wdt_mem); 240 kfree(wdt_mem); 241 wdt_mem = NULL; 242 } 243 return 0; 244 } 245 246 static struct platform_driver platform_wdt_driver = { 247 .driver = { 248 .name = "watchdog", 249 .owner = THIS_MODULE, 250 }, 251 .probe = davinci_wdt_probe, 252 .remove = davinci_wdt_remove, 253 }; 254 255 static int __init davinci_wdt_init(void) 256 { 257 return platform_driver_register(&platform_wdt_driver); 258 } 259 260 static void __exit davinci_wdt_exit(void) 261 { 262 platform_driver_unregister(&platform_wdt_driver); 263 } 264 265 module_init(davinci_wdt_init); 266 module_exit(davinci_wdt_exit); 267 268 MODULE_AUTHOR("Texas Instruments"); 269 MODULE_DESCRIPTION("DaVinci Watchdog Driver"); 270 271 module_param(heartbeat, int, 0); 272 MODULE_PARM_DESC(heartbeat, 273 "Watchdog heartbeat period in seconds from 1 to " 274 __MODULE_STRING(MAX_HEARTBEAT) ", default " 275 __MODULE_STRING(DEFAULT_HEARTBEAT)); 276 277 MODULE_LICENSE("GPL"); 278 MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR); 279 MODULE_ALIAS("platform:watchdog"); 280