diff options
Diffstat (limited to 'drivers/watchdog/ar7_wdt.c')
| -rw-r--r-- | drivers/watchdog/ar7_wdt.c | 331 |
1 files changed, 331 insertions, 0 deletions
diff --git a/drivers/watchdog/ar7_wdt.c b/drivers/watchdog/ar7_wdt.c new file mode 100644 index 000000000..6d5ae251e --- /dev/null +++ b/drivers/watchdog/ar7_wdt.c @@ -0,0 +1,331 @@ +/* + * 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 = { + .name = "ar7_wdt", + }, +}; + +module_platform_driver(ar7_wdt_driver); |