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 <linux/device.h> 28 #include <linux/clk.h> 29 #include <linux/slab.h> 30 31 #define MODULE_NAME "DAVINCI-WDT: " 32 33 #define DEFAULT_HEARTBEAT 60 34 #define MAX_HEARTBEAT 600 /* really the max margin is 264/27MHz*/ 35 36 /* Timer register set definition */ 37 #define PID12 (0x0) 38 #define EMUMGT (0x4) 39 #define TIM12 (0x10) 40 #define TIM34 (0x14) 41 #define PRD12 (0x18) 42 #define PRD34 (0x1C) 43 #define TCR (0x20) 44 #define TGCR (0x24) 45 #define WDTCR (0x28) 46 47 /* TCR bit definitions */ 48 #define ENAMODE12_DISABLED (0 << 6) 49 #define ENAMODE12_ONESHOT (1 << 6) 50 #define ENAMODE12_PERIODIC (2 << 6) 51 52 /* TGCR bit definitions */ 53 #define TIM12RS_UNRESET (1 << 0) 54 #define TIM34RS_UNRESET (1 << 1) 55 #define TIMMODE_64BIT_WDOG (2 << 2) 56 57 /* WDTCR bit definitions */ 58 #define WDEN (1 << 14) 59 #define WDFLAG (1 << 15) 60 #define WDKEY_SEQ0 (0xa5c6 << 16) 61 #define WDKEY_SEQ1 (0xda7e << 16) 62 63 static int heartbeat = DEFAULT_HEARTBEAT; 64 65 static DEFINE_SPINLOCK(io_lock); 66 static unsigned long wdt_status; 67 #define WDT_IN_USE 0 68 #define WDT_OK_TO_CLOSE 1 69 #define WDT_REGION_INITED 2 70 #define WDT_DEVICE_INITED 3 71 72 static struct resource *wdt_mem; 73 static void __iomem *wdt_base; 74 struct clk *wdt_clk; 75 76 static void wdt_service(void) 77 { 78 spin_lock(&io_lock); 79 80 /* put watchdog in service state */ 81 iowrite32(WDKEY_SEQ0, wdt_base + WDTCR); 82 /* put watchdog in active state */ 83 iowrite32(WDKEY_SEQ1, wdt_base + WDTCR); 84 85 spin_unlock(&io_lock); 86 } 87 88 static void wdt_enable(void) 89 { 90 u32 tgcr; 91 u32 timer_margin; 92 unsigned long wdt_freq; 93 94 wdt_freq = clk_get_rate(wdt_clk); 95 96 spin_lock(&io_lock); 97 98 /* disable, internal clock source */ 99 iowrite32(0, wdt_base + TCR); 100 /* reset timer, set mode to 64-bit watchdog, and unreset */ 101 iowrite32(0, wdt_base + TGCR); 102 tgcr = TIMMODE_64BIT_WDOG | TIM12RS_UNRESET | TIM34RS_UNRESET; 103 iowrite32(tgcr, wdt_base + TGCR); 104 /* clear counter regs */ 105 iowrite32(0, wdt_base + TIM12); 106 iowrite32(0, wdt_base + TIM34); 107 /* set timeout period */ 108 timer_margin = (((u64)heartbeat * wdt_freq) & 0xffffffff); 109 iowrite32(timer_margin, wdt_base + PRD12); 110 timer_margin = (((u64)heartbeat * wdt_freq) >> 32); 111 iowrite32(timer_margin, wdt_base + PRD34); 112 /* enable run continuously */ 113 iowrite32(ENAMODE12_PERIODIC, wdt_base + TCR); 114 /* Once the WDT is in pre-active state write to 115 * TIM12, TIM34, PRD12, PRD34, TCR, TGCR, WDTCR are 116 * write protected (except for the WDKEY field) 117 */ 118 /* put watchdog in pre-active state */ 119 iowrite32(WDKEY_SEQ0 | WDEN, wdt_base + WDTCR); 120 /* put watchdog in active state */ 121 iowrite32(WDKEY_SEQ1 | WDEN, wdt_base + WDTCR); 122 123 spin_unlock(&io_lock); 124 } 125 126 static int davinci_wdt_open(struct inode *inode, struct file *file) 127 { 128 if (test_and_set_bit(WDT_IN_USE, &wdt_status)) 129 return -EBUSY; 130 131 wdt_enable(); 132 133 return nonseekable_open(inode, file); 134 } 135 136 static ssize_t 137 davinci_wdt_write(struct file *file, const char *data, size_t len, 138 loff_t *ppos) 139 { 140 if (len) 141 wdt_service(); 142 143 return len; 144 } 145 146 static const struct watchdog_info ident = { 147 .options = WDIOF_KEEPALIVEPING, 148 .identity = "DaVinci Watchdog", 149 }; 150 151 static long davinci_wdt_ioctl(struct file *file, 152 unsigned int cmd, unsigned long arg) 153 { 154 int ret = -ENOTTY; 155 156 switch (cmd) { 157 case WDIOC_GETSUPPORT: 158 ret = copy_to_user((struct watchdog_info *)arg, &ident, 159 sizeof(ident)) ? -EFAULT : 0; 160 break; 161 162 case WDIOC_GETSTATUS: 163 case WDIOC_GETBOOTSTATUS: 164 ret = put_user(0, (int *)arg); 165 break; 166 167 case WDIOC_KEEPALIVE: 168 wdt_service(); 169 ret = 0; 170 break; 171 172 case WDIOC_GETTIMEOUT: 173 ret = put_user(heartbeat, (int *)arg); 174 break; 175 } 176 return ret; 177 } 178 179 static int davinci_wdt_release(struct inode *inode, struct file *file) 180 { 181 wdt_service(); 182 clear_bit(WDT_IN_USE, &wdt_status); 183 184 return 0; 185 } 186 187 static const struct file_operations davinci_wdt_fops = { 188 .owner = THIS_MODULE, 189 .llseek = no_llseek, 190 .write = davinci_wdt_write, 191 .unlocked_ioctl = davinci_wdt_ioctl, 192 .open = davinci_wdt_open, 193 .release = davinci_wdt_release, 194 }; 195 196 static struct miscdevice davinci_wdt_miscdev = { 197 .minor = WATCHDOG_MINOR, 198 .name = "watchdog", 199 .fops = &davinci_wdt_fops, 200 }; 201 202 static int davinci_wdt_probe(struct platform_device *pdev) 203 { 204 int ret = 0, size; 205 struct device *dev = &pdev->dev; 206 207 wdt_clk = clk_get(dev, NULL); 208 if (WARN_ON(IS_ERR(wdt_clk))) 209 return PTR_ERR(wdt_clk); 210 211 clk_enable(wdt_clk); 212 213 if (heartbeat < 1 || heartbeat > MAX_HEARTBEAT) 214 heartbeat = DEFAULT_HEARTBEAT; 215 216 dev_info(dev, "heartbeat %d sec\n", heartbeat); 217 218 wdt_mem = platform_get_resource(pdev, IORESOURCE_MEM, 0); 219 if (wdt_mem == NULL) { 220 dev_err(dev, "failed to get memory region resource\n"); 221 return -ENOENT; 222 } 223 224 size = resource_size(wdt_mem); 225 if (!request_mem_region(wdt_mem->start, size, pdev->name)) { 226 dev_err(dev, "failed to get memory region\n"); 227 return -ENOENT; 228 } 229 230 wdt_base = ioremap(wdt_mem->start, size); 231 if (!wdt_base) { 232 dev_err(dev, "failed to map memory region\n"); 233 release_mem_region(wdt_mem->start, size); 234 wdt_mem = NULL; 235 return -ENOMEM; 236 } 237 238 ret = misc_register(&davinci_wdt_miscdev); 239 if (ret < 0) { 240 dev_err(dev, "cannot register misc device\n"); 241 release_mem_region(wdt_mem->start, size); 242 wdt_mem = NULL; 243 } else { 244 set_bit(WDT_DEVICE_INITED, &wdt_status); 245 } 246 247 iounmap(wdt_base); 248 return ret; 249 } 250 251 static int davinci_wdt_remove(struct platform_device *pdev) 252 { 253 misc_deregister(&davinci_wdt_miscdev); 254 if (wdt_mem) { 255 release_mem_region(wdt_mem->start, resource_size(wdt_mem)); 256 wdt_mem = NULL; 257 } 258 259 clk_disable(wdt_clk); 260 clk_put(wdt_clk); 261 262 return 0; 263 } 264 265 static struct platform_driver platform_wdt_driver = { 266 .driver = { 267 .name = "watchdog", 268 .owner = THIS_MODULE, 269 }, 270 .probe = davinci_wdt_probe, 271 .remove = davinci_wdt_remove, 272 }; 273 274 module_platform_driver(platform_wdt_driver); 275 276 MODULE_AUTHOR("Texas Instruments"); 277 MODULE_DESCRIPTION("DaVinci Watchdog Driver"); 278 279 module_param(heartbeat, int, 0); 280 MODULE_PARM_DESC(heartbeat, 281 "Watchdog heartbeat period in seconds from 1 to " 282 __MODULE_STRING(MAX_HEARTBEAT) ", default " 283 __MODULE_STRING(DEFAULT_HEARTBEAT)); 284 285 MODULE_LICENSE("GPL"); 286 MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR); 287 MODULE_ALIAS("platform:watchdog"); 288