/* * drivers/watchdog/ar7_wdt.c * * Copyright (C) 2007 Nicolas Thill <nico@openwrt.org> * Copyright (c) 2005 Enrik Berkhan <Enrik.Berkhan@akk.org> * * Some code taken from: * National Semiconductor SCx200 Watchdog support * Copyright (c) 2001,2002 Christer Weinigel <wingel@nano-system.com> * * 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. * * This program is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the * GNU General Public License for more details. * * You should have received a copy of the GNU General Public License * along with this program; if not, write to the Free Software * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA */ #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt #include <linux/module.h> #include <linux/moduleparam.h> #include <linux/errno.h> #include <linux/miscdevice.h> #include <linux/platform_device.h> #include <linux/watchdog.h> #include <linux/fs.h> #include <linux/ioport.h> #include <linux/io.h> #include <linux/uaccess.h> #include <linux/clk.h> #include <asm/addrspace.h> #include <asm/mach-ar7/ar7.h> #define LONGNAME "TI AR7 Watchdog Timer" MODULE_AUTHOR("Nicolas Thill <nico@openwrt.org>"); MODULE_DESCRIPTION(LONGNAME); MODULE_LICENSE("GPL"); static int margin = 60; module_param(margin, int, 0); MODULE_PARM_DESC(margin, "Watchdog margin in seconds"); static bool nowayout = WATCHDOG_NOWAYOUT; module_param(nowayout, bool, 0); MODULE_PARM_DESC(nowayout, "Disable watchdog shutdown on close"); #define READ_REG(x) readl((void __iomem *)&(x)) #define WRITE_REG(x, v) writel((v), (void __iomem *)&(x)) struct ar7_wdt { u32 kick_lock; u32 kick; u32 change_lock; u32 change; u32 disable_lock; u32 disable; u32 prescale_lock; u32 prescale; }; static unsigned long wdt_is_open; static unsigned expect_close; static DEFINE_SPINLOCK(wdt_lock); /* XXX currently fixed, allows max margin ~68.72 secs */ #define prescale_value 0xffff /* Resource of the WDT registers */ static struct resource *ar7_regs_wdt; /* Pointer to the remapped WDT IO space */ static struct ar7_wdt *ar7_wdt; static struct clk *vbus_clk; static void ar7_wdt_kick(u32 value) { WRITE_REG(ar7_wdt->kick_lock, 0x5555); if ((READ_REG(ar7_wdt->kick_lock) & 3) == 1) { WRITE_REG(ar7_wdt->kick_lock, 0xaaaa); if ((READ_REG(ar7_wdt->kick_lock) & 3) == 3) { WRITE_REG(ar7_wdt->kick, value); return; } } pr_err("failed to unlock WDT kick reg\n"); } static void ar7_wdt_prescale(u32 value) { WRITE_REG(ar7_wdt->prescale_lock, 0x5a5a); if ((READ_REG(ar7_wdt->prescale_lock) & 3) == 1) { WRITE_REG(ar7_wdt->prescale_lock, 0xa5a5); if ((READ_REG(ar7_wdt->prescale_lock) & 3) == 3) { WRITE_REG(ar7_wdt->prescale, value); return; } } pr_err("failed to unlock WDT prescale reg\n"); } static void ar7_wdt_change(u32 value) { WRITE_REG(ar7_wdt->change_lock, 0x6666); if ((READ_REG(ar7_wdt->change_lock) & 3) == 1) { WRITE_REG(ar7_wdt->change_lock, 0xbbbb); if ((READ_REG(ar7_wdt->change_lock) & 3) == 3) { WRITE_REG(ar7_wdt->change, value); return; } } pr_err("failed to unlock WDT change reg\n"); } static void ar7_wdt_disable(u32 value) { WRITE_REG(ar7_wdt->disable_lock, 0x7777); if ((READ_REG(ar7_wdt->disable_lock) & 3) == 1) { WRITE_REG(ar7_wdt->disable_lock, 0xcccc); if ((READ_REG(ar7_wdt->disable_lock) & 3) == 2) { WRITE_REG(ar7_wdt->disable_lock, 0xdddd); if ((READ_REG(ar7_wdt->disable_lock) & 3) == 3) { WRITE_REG(ar7_wdt->disable, value); return; } } } pr_err("failed to unlock WDT disable reg\n"); } static void ar7_wdt_update_margin(int new_margin) { u32 change; u32 vbus_rate; vbus_rate = clk_get_rate(vbus_clk); change = new_margin * (vbus_rate / prescale_value); if (change < 1) change = 1; if (change > 0xffff) change = 0xffff; ar7_wdt_change(change); margin = change * prescale_value / vbus_rate; pr_info("timer margin %d seconds (prescale %d, change %d, freq %d)\n", margin, prescale_value, change, vbus_rate); } static void ar7_wdt_enable_wdt(void) { pr_debug("enabling watchdog timer\n"); ar7_wdt_disable(1); ar7_wdt_kick(1); } static void ar7_wdt_disable_wdt(void) { pr_debug("disabling watchdog timer\n"); ar7_wdt_disable(0); } static int ar7_wdt_open(struct inode *inode, struct file *file) { /* only allow one at a time */ if (test_and_set_bit(0, &wdt_is_open)) return -EBUSY; ar7_wdt_enable_wdt(); expect_close = 0; return nonseekable_open(inode, file); } static int ar7_wdt_release(struct inode *inode, struct file *file) { if (!expect_close) pr_warn("watchdog device closed unexpectedly, will not disable the watchdog timer\n"); else if (!nowayout) ar7_wdt_disable_wdt(); clear_bit(0, &wdt_is_open); return 0; } static ssize_t ar7_wdt_write(struct file *file, const char *data, size_t len, loff_t *ppos) { /* check for a magic close character */ if (len) { size_t i; spin_lock(&wdt_lock); ar7_wdt_kick(1); spin_unlock(&wdt_lock); expect_close = 0; for (i = 0; i < len; ++i) { char c; if (get_user(c, data + i)) return -EFAULT; if (c == 'V') expect_close = 1; } } return len; } static long ar7_wdt_ioctl(struct file *file, unsigned int cmd, unsigned long arg) { static const struct watchdog_info ident = { .identity = LONGNAME, .firmware_version = 1, .options = (WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE), }; int new_margin; switch (cmd) { case WDIOC_GETSUPPORT: if (copy_to_user((struct watchdog_info *)arg, &ident, sizeof(ident))) return -EFAULT; return 0; case WDIOC_GETSTATUS: case WDIOC_GETBOOTSTATUS: if (put_user(0, (int *)arg)) return -EFAULT; return 0; case WDIOC_KEEPALIVE: ar7_wdt_kick(1); return 0; case WDIOC_SETTIMEOUT: if (get_user(new_margin, (int *)arg)) return -EFAULT; if (new_margin < 1) return -EINVAL; spin_lock(&wdt_lock); ar7_wdt_update_margin(new_margin); ar7_wdt_kick(1); spin_unlock(&wdt_lock); case WDIOC_GETTIMEOUT: if (put_user(margin, (int *)arg)) return -EFAULT; return 0; default: return -ENOTTY; } } static const struct file_operations ar7_wdt_fops = { .owner = THIS_MODULE, .write = ar7_wdt_write, .unlocked_ioctl = ar7_wdt_ioctl, .open = ar7_wdt_open, .release = ar7_wdt_release, .llseek = no_llseek, }; static struct miscdevice ar7_wdt_miscdev = { .minor = WATCHDOG_MINOR, .name = "watchdog", .fops = &ar7_wdt_fops, }; static int ar7_wdt_probe(struct platform_device *pdev) { int rc; ar7_regs_wdt = platform_get_resource_byname(pdev, IORESOURCE_MEM, "regs"); ar7_wdt = devm_ioremap_resource(&pdev->dev, ar7_regs_wdt); if (IS_ERR(ar7_wdt)) return PTR_ERR(ar7_wdt); vbus_clk = clk_get(NULL, "vbus"); if (IS_ERR(vbus_clk)) { pr_err("could not get vbus clock\n"); return PTR_ERR(vbus_clk); } ar7_wdt_disable_wdt(); ar7_wdt_prescale(prescale_value); ar7_wdt_update_margin(margin); rc = misc_register(&ar7_wdt_miscdev); if (rc) { pr_err("unable to register misc device\n"); goto out; } return 0; out: clk_put(vbus_clk); vbus_clk = NULL; return rc; } static int ar7_wdt_remove(struct platform_device *pdev) { misc_deregister(&ar7_wdt_miscdev); clk_put(vbus_clk); vbus_clk = NULL; return 0; } static void ar7_wdt_shutdown(struct platform_device *pdev) { if (!nowayout) ar7_wdt_disable_wdt(); } static struct platform_driver ar7_wdt_driver = { .probe = ar7_wdt_probe, .remove = ar7_wdt_remove, .shutdown = ar7_wdt_shutdown, .driver = { .owner = THIS_MODULE, .name = "ar7_wdt", }, }; module_platform_driver(ar7_wdt_driver);