gef_wdt.c 7.5 KB
Newer Older
1
/*
2
 * GE watchdog userspace interface
3
 *
4
 * Author:  Martyn Welch <martyn.welch@ge.com>
5
 *
6
 * Copyright 2008 GE Intelligent Platforms Embedded Systems, Inc.
7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32
 *
 * This program is free software; you can redistribute  it and/or modify it
 * under  the terms of  the GNU General  Public License as published by the
 * Free Software Foundation;  either version 2 of the  License, or (at your
 * option) any later version.
 *
 * Based on: mv64x60_wdt.c (MV64X60 watchdog userspace interface)
 *   Author: James Chapman <jchapman@katalix.com>
 */

/* TODO:
 * This driver does not provide support for the hardwares capability of sending
 * an interrupt at a programmable threshold.
 *
 * This driver currently can only support 1 watchdog - there are 2 in the
 * hardware that this driver supports. Thus one could be configured as a
 * process-based watchdog (via /dev/watchdog), the second (using the interrupt
 * capabilities) a kernel-based watchdog.
 */

#include <linux/kernel.h>
#include <linux/compiler.h>
#include <linux/init.h>
#include <linux/module.h>
#include <linux/miscdevice.h>
#include <linux/watchdog.h>
33
#include <linux/fs.h>
34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164
#include <linux/of.h>
#include <linux/of_platform.h>
#include <linux/io.h>
#include <linux/uaccess.h>

#include <sysdev/fsl_soc.h>

/*
 * The watchdog configuration register contains a pair of 2-bit fields,
 *   1.  a reload field, bits 27-26, which triggers a reload of
 *       the countdown register, and
 *   2.  an enable field, bits 25-24, which toggles between
 *       enabling and disabling the watchdog timer.
 * Bit 31 is a read-only field which indicates whether the
 * watchdog timer is currently enabled.
 *
 * The low 24 bits contain the timer reload value.
 */
#define GEF_WDC_ENABLE_SHIFT	24
#define GEF_WDC_SERVICE_SHIFT	26
#define GEF_WDC_ENABLED_SHIFT	31

#define GEF_WDC_ENABLED_TRUE	1
#define GEF_WDC_ENABLED_FALSE	0

/* Flags bits */
#define GEF_WDOG_FLAG_OPENED	0

static unsigned long wdt_flags;
static int wdt_status;
static void __iomem *gef_wdt_regs;
static int gef_wdt_timeout;
static int gef_wdt_count;
static unsigned int bus_clk;
static char expect_close;
static DEFINE_SPINLOCK(gef_wdt_spinlock);

static int nowayout = WATCHDOG_NOWAYOUT;
module_param(nowayout, int, 0);
MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="
	__MODULE_STRING(WATCHDOG_NOWAYOUT) ")");


static int gef_wdt_toggle_wdc(int enabled_predicate, int field_shift)
{
	u32 data;
	u32 enabled;
	int ret = 0;

	spin_lock(&gef_wdt_spinlock);
	data = ioread32be(gef_wdt_regs);
	enabled = (data >> GEF_WDC_ENABLED_SHIFT) & 1;

	/* only toggle the requested field if enabled state matches predicate */
	if ((enabled ^ enabled_predicate) == 0) {
		/* We write a 1, then a 2 -- to the appropriate field */
		data = (1 << field_shift) | gef_wdt_count;
		iowrite32be(data, gef_wdt_regs);

		data = (2 << field_shift) | gef_wdt_count;
		iowrite32be(data, gef_wdt_regs);
		ret = 1;
	}
	spin_unlock(&gef_wdt_spinlock);

	return ret;
}

static void gef_wdt_service(void)
{
	gef_wdt_toggle_wdc(GEF_WDC_ENABLED_TRUE,
		GEF_WDC_SERVICE_SHIFT);
}

static void gef_wdt_handler_enable(void)
{
	if (gef_wdt_toggle_wdc(GEF_WDC_ENABLED_FALSE,
				   GEF_WDC_ENABLE_SHIFT)) {
		gef_wdt_service();
		printk(KERN_NOTICE "gef_wdt: watchdog activated\n");
	}
}

static void gef_wdt_handler_disable(void)
{
	if (gef_wdt_toggle_wdc(GEF_WDC_ENABLED_TRUE,
				   GEF_WDC_ENABLE_SHIFT))
		printk(KERN_NOTICE "gef_wdt: watchdog deactivated\n");
}

static void gef_wdt_set_timeout(unsigned int timeout)
{
	/* maximum bus cycle count is 0xFFFFFFFF */
	if (timeout > 0xFFFFFFFF / bus_clk)
		timeout = 0xFFFFFFFF / bus_clk;

	/* Register only holds upper 24 bits, bit shifted into lower 24 */
	gef_wdt_count = (timeout * bus_clk) >> 8;
	gef_wdt_timeout = timeout;
}


static ssize_t gef_wdt_write(struct file *file, const char __user *data,
				 size_t len, loff_t *ppos)
{
	if (len) {
		if (!nowayout) {
			size_t i;

			expect_close = 0;

			for (i = 0; i != len; i++) {
				char c;
				if (get_user(c, data + i))
					return -EFAULT;
				if (c == 'V')
					expect_close = 42;
			}
		}
		gef_wdt_service();
	}

	return len;
}

static long gef_wdt_ioctl(struct file *file, unsigned int cmd,
							unsigned long arg)
{
	int timeout;
	int options;
	void __user *argp = (void __user *)arg;
165
	static const struct watchdog_info info = {
166 167 168
		.options =	WDIOF_SETTIMEOUT | WDIOF_MAGICCLOSE |
				WDIOF_KEEPALIVEPING,
		.firmware_version = 0,
169
		.identity = "GE watchdog",
170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263
	};

	switch (cmd) {
	case WDIOC_GETSUPPORT:
		if (copy_to_user(argp, &info, sizeof(info)))
			return -EFAULT;
		break;

	case WDIOC_GETSTATUS:
	case WDIOC_GETBOOTSTATUS:
		if (put_user(wdt_status, (int __user *)argp))
			return -EFAULT;
		wdt_status &= ~WDIOF_KEEPALIVEPING;
		break;

	case WDIOC_SETOPTIONS:
		if (get_user(options, (int __user *)argp))
			return -EFAULT;

		if (options & WDIOS_DISABLECARD)
			gef_wdt_handler_disable();

		if (options & WDIOS_ENABLECARD)
			gef_wdt_handler_enable();
		break;

	case WDIOC_KEEPALIVE:
		gef_wdt_service();
		wdt_status |= WDIOF_KEEPALIVEPING;
		break;

	case WDIOC_SETTIMEOUT:
		if (get_user(timeout, (int __user *)argp))
			return -EFAULT;
		gef_wdt_set_timeout(timeout);
		/* Fall through */

	case WDIOC_GETTIMEOUT:
		if (put_user(gef_wdt_timeout, (int __user *)argp))
			return -EFAULT;
		break;

	default:
		return -ENOTTY;
	}

	return 0;
}

static int gef_wdt_open(struct inode *inode, struct file *file)
{
	if (test_and_set_bit(GEF_WDOG_FLAG_OPENED, &wdt_flags))
		return -EBUSY;

	if (nowayout)
		__module_get(THIS_MODULE);

	gef_wdt_handler_enable();

	return nonseekable_open(inode, file);
}

static int gef_wdt_release(struct inode *inode, struct file *file)
{
	if (expect_close == 42)
		gef_wdt_handler_disable();
	else {
		printk(KERN_CRIT
		       "gef_wdt: unexpected close, not stopping timer!\n");
		gef_wdt_service();
	}
	expect_close = 0;

	clear_bit(GEF_WDOG_FLAG_OPENED, &wdt_flags);

	return 0;
}

static const struct file_operations gef_wdt_fops = {
	.owner = THIS_MODULE,
	.llseek = no_llseek,
	.write = gef_wdt_write,
	.unlocked_ioctl = gef_wdt_ioctl,
	.open = gef_wdt_open,
	.release = gef_wdt_release,
};

static struct miscdevice gef_wdt_miscdev = {
	.minor = WATCHDOG_MINOR,
	.name = "watchdog",
	.fops = &gef_wdt_fops,
};


264
static int __devinit gef_wdt_probe(struct platform_device *dev)
265 266 267 268 269 270 271
{
	int timeout = 10;
	u32 freq;

	bus_clk = 133; /* in MHz */

	freq = fsl_get_sys_freq();
272
	if (freq != -1)
273 274 275
		bus_clk = freq;

	/* Map devices registers into memory */
276
	gef_wdt_regs = of_iomap(dev->dev.of_node, 0);
277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304
	if (gef_wdt_regs == NULL)
		return -ENOMEM;

	gef_wdt_set_timeout(timeout);

	gef_wdt_handler_disable();	/* in case timer was already running */

	return misc_register(&gef_wdt_miscdev);
}

static int __devexit gef_wdt_remove(struct platform_device *dev)
{
	misc_deregister(&gef_wdt_miscdev);

	gef_wdt_handler_disable();

	iounmap(gef_wdt_regs);

	return 0;
}

static const struct of_device_id gef_wdt_ids[] = {
	{
		.compatible = "gef,fpga-wdt",
	},
	{},
};

305
static struct platform_driver gef_wdt_driver = {
306 307 308 309 310
	.driver = {
		.name = "gef_wdt",
		.owner = THIS_MODULE,
		.of_match_table = gef_wdt_ids,
	},
311 312 313 314 315
	.probe		= gef_wdt_probe,
};

static int __init gef_wdt_init(void)
{
316
	printk(KERN_INFO "GE watchdog driver\n");
317
	return platform_driver_register(&gef_wdt_driver);
318 319 320 321
}

static void __exit gef_wdt_exit(void)
{
322
	platform_driver_unregister(&gef_wdt_driver);
323 324 325 326 327
}

module_init(gef_wdt_init);
module_exit(gef_wdt_exit);

328 329
MODULE_AUTHOR("Martyn Welch <martyn.welch@ge.com>");
MODULE_DESCRIPTION("GE watchdog driver");
330 331
MODULE_LICENSE("GPL");
MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
332
MODULE_ALIAS("platform:gef_wdt");