2 * GE watchdog userspace interface
4 * Author: Martyn Welch <martyn.welch@ge.com>
6 * Copyright 2008 GE Intelligent Platforms Embedded Systems, Inc.
8 * This program is free software; you can redistribute it and/or modify it
9 * under the terms of the GNU General Public License as published by the
10 * Free Software Foundation; either version 2 of the License, or (at your
11 * option) any later version.
13 * Based on: mv64x60_wdt.c (MV64X60 watchdog userspace interface)
14 * Author: James Chapman <jchapman@katalix.com>
18 * This driver does not provide support for the hardwares capability of sending
19 * an interrupt at a programmable threshold.
21 * This driver currently can only support 1 watchdog - there are 2 in the
22 * hardware that this driver supports. Thus one could be configured as a
23 * process-based watchdog (via /dev/watchdog), the second (using the interrupt
24 * capabilities) a kernel-based watchdog.
27 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
29 #include <linux/kernel.h>
30 #include <linux/compiler.h>
31 #include <linux/init.h>
32 #include <linux/module.h>
33 #include <linux/miscdevice.h>
34 #include <linux/watchdog.h>
37 #include <linux/of_address.h>
38 #include <linux/of_platform.h>
40 #include <linux/uaccess.h>
42 #include <sysdev/fsl_soc.h>
45 * The watchdog configuration register contains a pair of 2-bit fields,
46 * 1. a reload field, bits 27-26, which triggers a reload of
47 * the countdown register, and
48 * 2. an enable field, bits 25-24, which toggles between
49 * enabling and disabling the watchdog timer.
50 * Bit 31 is a read-only field which indicates whether the
51 * watchdog timer is currently enabled.
53 * The low 24 bits contain the timer reload value.
55 #define GEF_WDC_ENABLE_SHIFT 24
56 #define GEF_WDC_SERVICE_SHIFT 26
57 #define GEF_WDC_ENABLED_SHIFT 31
59 #define GEF_WDC_ENABLED_TRUE 1
60 #define GEF_WDC_ENABLED_FALSE 0
63 #define GEF_WDOG_FLAG_OPENED 0
65 static unsigned long wdt_flags;
66 static int wdt_status;
67 static void __iomem *gef_wdt_regs;
68 static int gef_wdt_timeout;
69 static int gef_wdt_count;
70 static unsigned int bus_clk;
71 static char expect_close;
72 static DEFINE_SPINLOCK(gef_wdt_spinlock);
74 static bool nowayout = WATCHDOG_NOWAYOUT;
75 module_param(nowayout, bool, 0);
76 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="
77 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
80 static int gef_wdt_toggle_wdc(int enabled_predicate, int field_shift)
86 spin_lock(&gef_wdt_spinlock);
87 data = ioread32be(gef_wdt_regs);
88 enabled = (data >> GEF_WDC_ENABLED_SHIFT) & 1;
90 /* only toggle the requested field if enabled state matches predicate */
91 if ((enabled ^ enabled_predicate) == 0) {
92 /* We write a 1, then a 2 -- to the appropriate field */
93 data = (1 << field_shift) | gef_wdt_count;
94 iowrite32be(data, gef_wdt_regs);
96 data = (2 << field_shift) | gef_wdt_count;
97 iowrite32be(data, gef_wdt_regs);
100 spin_unlock(&gef_wdt_spinlock);
105 static void gef_wdt_service(void)
107 gef_wdt_toggle_wdc(GEF_WDC_ENABLED_TRUE,
108 GEF_WDC_SERVICE_SHIFT);
111 static void gef_wdt_handler_enable(void)
113 if (gef_wdt_toggle_wdc(GEF_WDC_ENABLED_FALSE,
114 GEF_WDC_ENABLE_SHIFT)) {
116 pr_notice("watchdog activated\n");
120 static void gef_wdt_handler_disable(void)
122 if (gef_wdt_toggle_wdc(GEF_WDC_ENABLED_TRUE,
123 GEF_WDC_ENABLE_SHIFT))
124 pr_notice("watchdog deactivated\n");
127 static void gef_wdt_set_timeout(unsigned int timeout)
129 /* maximum bus cycle count is 0xFFFFFFFF */
130 if (timeout > 0xFFFFFFFF / bus_clk)
131 timeout = 0xFFFFFFFF / bus_clk;
133 /* Register only holds upper 24 bits, bit shifted into lower 24 */
134 gef_wdt_count = (timeout * bus_clk) >> 8;
135 gef_wdt_timeout = timeout;
139 static ssize_t gef_wdt_write(struct file *file, const char __user *data,
140 size_t len, loff_t *ppos)
148 for (i = 0; i != len; i++) {
150 if (get_user(c, data + i))
162 static long gef_wdt_ioctl(struct file *file, unsigned int cmd,
167 void __user *argp = (void __user *)arg;
168 static const struct watchdog_info info = {
169 .options = WDIOF_SETTIMEOUT | WDIOF_MAGICCLOSE |
171 .firmware_version = 0,
172 .identity = "GE watchdog",
176 case WDIOC_GETSUPPORT:
177 if (copy_to_user(argp, &info, sizeof(info)))
181 case WDIOC_GETSTATUS:
182 case WDIOC_GETBOOTSTATUS:
183 if (put_user(wdt_status, (int __user *)argp))
185 wdt_status &= ~WDIOF_KEEPALIVEPING;
188 case WDIOC_SETOPTIONS:
189 if (get_user(options, (int __user *)argp))
192 if (options & WDIOS_DISABLECARD)
193 gef_wdt_handler_disable();
195 if (options & WDIOS_ENABLECARD)
196 gef_wdt_handler_enable();
199 case WDIOC_KEEPALIVE:
201 wdt_status |= WDIOF_KEEPALIVEPING;
204 case WDIOC_SETTIMEOUT:
205 if (get_user(timeout, (int __user *)argp))
207 gef_wdt_set_timeout(timeout);
210 case WDIOC_GETTIMEOUT:
211 if (put_user(gef_wdt_timeout, (int __user *)argp))
222 static int gef_wdt_open(struct inode *inode, struct file *file)
224 if (test_and_set_bit(GEF_WDOG_FLAG_OPENED, &wdt_flags))
228 __module_get(THIS_MODULE);
230 gef_wdt_handler_enable();
232 return nonseekable_open(inode, file);
235 static int gef_wdt_release(struct inode *inode, struct file *file)
237 if (expect_close == 42)
238 gef_wdt_handler_disable();
240 pr_crit("unexpected close, not stopping timer!\n");
245 clear_bit(GEF_WDOG_FLAG_OPENED, &wdt_flags);
250 static const struct file_operations gef_wdt_fops = {
251 .owner = THIS_MODULE,
253 .write = gef_wdt_write,
254 .unlocked_ioctl = gef_wdt_ioctl,
255 .open = gef_wdt_open,
256 .release = gef_wdt_release,
259 static struct miscdevice gef_wdt_miscdev = {
260 .minor = WATCHDOG_MINOR,
262 .fops = &gef_wdt_fops,
266 static int gef_wdt_probe(struct platform_device *dev)
271 bus_clk = 133; /* in MHz */
273 freq = fsl_get_sys_freq();
277 /* Map devices registers into memory */
278 gef_wdt_regs = of_iomap(dev->dev.of_node, 0);
279 if (gef_wdt_regs == NULL)
282 gef_wdt_set_timeout(timeout);
284 gef_wdt_handler_disable(); /* in case timer was already running */
286 return misc_register(&gef_wdt_miscdev);
289 static int gef_wdt_remove(struct platform_device *dev)
291 misc_deregister(&gef_wdt_miscdev);
293 gef_wdt_handler_disable();
295 iounmap(gef_wdt_regs);
300 static const struct of_device_id gef_wdt_ids[] = {
302 .compatible = "gef,fpga-wdt",
307 static struct platform_driver gef_wdt_driver = {
310 .owner = THIS_MODULE,
311 .of_match_table = gef_wdt_ids,
313 .probe = gef_wdt_probe,
314 .remove = gef_wdt_remove,
317 static int __init gef_wdt_init(void)
319 pr_info("GE watchdog driver\n");
320 return platform_driver_register(&gef_wdt_driver);
323 static void __exit gef_wdt_exit(void)
325 platform_driver_unregister(&gef_wdt_driver);
328 module_init(gef_wdt_init);
329 module_exit(gef_wdt_exit);
331 MODULE_AUTHOR("Martyn Welch <martyn.welch@ge.com>");
332 MODULE_DESCRIPTION("GE watchdog driver");
333 MODULE_LICENSE("GPL");
334 MODULE_ALIAS("platform:gef_wdt");