/* * GE watchdog userspace interface * * Author: Martyn Welch * * Copyright 2008 GE Intelligent Platforms Embedded Systems, Inc. * * 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 */ /* 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. */ #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt #include #include #include #include #include #include #include #include #include #include #include #include /* * 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 bool nowayout = WATCHDOG_NOWAYOUT; module_param(nowayout, bool, 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(); pr_notice("watchdog activated\n"); } } static void gef_wdt_handler_disable(void) { if (gef_wdt_toggle_wdc(GEF_WDC_ENABLED_TRUE, GEF_WDC_ENABLE_SHIFT)) pr_notice("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; static const struct watchdog_info info = { .options = WDIOF_SETTIMEOUT | WDIOF_MAGICCLOSE | WDIOF_KEEPALIVEPING, .firmware_version = 0, .identity = "GE watchdog", }; 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 { pr_crit("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, }; static int gef_wdt_probe(struct platform_device *dev) { int timeout = 10; u32 freq; bus_clk = 133; /* in MHz */ freq = fsl_get_sys_freq(); if (freq != -1) bus_clk = freq; /* Map devices registers into memory */ gef_wdt_regs = of_iomap(dev->dev.of_node, 0); 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 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", }, {}, }; static struct platform_driver gef_wdt_driver = { .driver = { .name = "gef_wdt", .owner = THIS_MODULE, .of_match_table = gef_wdt_ids, }, .probe = gef_wdt_probe, .remove = gef_wdt_remove, }; static int __init gef_wdt_init(void) { pr_info("GE watchdog driver\n"); return platform_driver_register(&gef_wdt_driver); } static void __exit gef_wdt_exit(void) { platform_driver_unregister(&gef_wdt_driver); } module_init(gef_wdt_init); module_exit(gef_wdt_exit); MODULE_AUTHOR("Martyn Welch "); MODULE_DESCRIPTION("GE watchdog driver"); MODULE_LICENSE("GPL"); MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR); MODULE_ALIAS("platform:gef_wdt");