/* * mv64x60_wdt.c - MV64X60 (Marvell Discovery) watchdog userspace interface * * Author: James Chapman * * Platform-specific setup code should configure the dog to generate * interrupt or reset as required. This code only enables/disables * and services the watchdog. * * Derived from mpc8xx_wdt.c, with the following copyright. * * 2002 (c) Florian Schirmer This file is licensed under * the terms of the GNU General Public License version 2. This program * is licensed "as is" without any warranty of any kind, whether express * or implied. */ #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt #include #include #include #include #include #include #include #include #include #include #define MV64x60_WDT_WDC_OFFSET 0 /* * 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 MV64x60_WDC_ENABLE_SHIFT 24 #define MV64x60_WDC_SERVICE_SHIFT 26 #define MV64x60_WDC_ENABLED_SHIFT 31 #define MV64x60_WDC_ENABLED_TRUE 1 #define MV64x60_WDC_ENABLED_FALSE 0 /* Flags bits */ #define MV64x60_WDOG_FLAG_OPENED 0 static unsigned long wdt_flags; static int wdt_status; static void __iomem *mv64x60_wdt_regs; static int mv64x60_wdt_timeout; static int mv64x60_wdt_count; static unsigned int bus_clk; static char expect_close; static DEFINE_SPINLOCK(mv64x60_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 mv64x60_wdt_toggle_wdc(int enabled_predicate, int field_shift) { u32 data; u32 enabled; int ret = 0; spin_lock(&mv64x60_wdt_spinlock); data = readl(mv64x60_wdt_regs + MV64x60_WDT_WDC_OFFSET); enabled = (data >> MV64x60_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) | mv64x60_wdt_count; writel(data, mv64x60_wdt_regs + MV64x60_WDT_WDC_OFFSET); data = (2 << field_shift) | mv64x60_wdt_count; writel(data, mv64x60_wdt_regs + MV64x60_WDT_WDC_OFFSET); ret = 1; } spin_unlock(&mv64x60_wdt_spinlock); return ret; } static void mv64x60_wdt_service(void) { mv64x60_wdt_toggle_wdc(MV64x60_WDC_ENABLED_TRUE, MV64x60_WDC_SERVICE_SHIFT); } static void mv64x60_wdt_handler_enable(void) { if (mv64x60_wdt_toggle_wdc(MV64x60_WDC_ENABLED_FALSE, MV64x60_WDC_ENABLE_SHIFT)) { mv64x60_wdt_service(); pr_notice("watchdog activated\n"); } } static void mv64x60_wdt_handler_disable(void) { if (mv64x60_wdt_toggle_wdc(MV64x60_WDC_ENABLED_TRUE, MV64x60_WDC_ENABLE_SHIFT)) pr_notice("watchdog deactivated\n"); } static void mv64x60_wdt_set_timeout(unsigned int timeout) { /* maximum bus cycle count is 0xFFFFFFFF */ if (timeout > 0xFFFFFFFF / bus_clk) timeout = 0xFFFFFFFF / bus_clk; mv64x60_wdt_count = timeout * bus_clk >> 8; mv64x60_wdt_timeout = timeout; } static int mv64x60_wdt_open(struct inode *inode, struct file *file) { if (test_and_set_bit(MV64x60_WDOG_FLAG_OPENED, &wdt_flags)) return -EBUSY; if (nowayout) __module_get(THIS_MODULE); mv64x60_wdt_handler_enable(); return stream_open(inode, file); } static int mv64x60_wdt_release(struct inode *inode, struct file *file) { if (expect_close == 42) mv64x60_wdt_handler_disable(); else { pr_crit("unexpected close, not stopping timer!\n"); mv64x60_wdt_service(); } expect_close = 0; clear_bit(MV64x60_WDOG_FLAG_OPENED, &wdt_flags); return 0; } static ssize_t mv64x60_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; } } mv64x60_wdt_service(); } return len; } static long mv64x60_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 = "MV64x60 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_GETTEMP: return -EOPNOTSUPP; case WDIOC_SETOPTIONS: if (get_user(options, (int __user *)argp)) return -EFAULT; if (options & WDIOS_DISABLECARD) mv64x60_wdt_handler_disable(); if (options & WDIOS_ENABLECARD) mv64x60_wdt_handler_enable(); break; case WDIOC_KEEPALIVE: mv64x60_wdt_service(); wdt_status |= WDIOF_KEEPALIVEPING; break; case WDIOC_SETTIMEOUT: if (get_user(timeout, (int __user *)argp)) return -EFAULT; mv64x60_wdt_set_timeout(timeout); /* Fall through */ case WDIOC_GETTIMEOUT: if (put_user(mv64x60_wdt_timeout, (int __user *)argp)) return -EFAULT; break; default: return -ENOTTY; } return 0; } static const struct file_operations mv64x60_wdt_fops = { .owner = THIS_MODULE, .llseek = no_llseek, .write = mv64x60_wdt_write, .unlocked_ioctl = mv64x60_wdt_ioctl, .open = mv64x60_wdt_open, .release = mv64x60_wdt_release, }; static struct miscdevice mv64x60_wdt_miscdev = { .minor = WATCHDOG_MINOR, .name = "watchdog", .fops = &mv64x60_wdt_fops, }; static int mv64x60_wdt_probe(struct platform_device *dev) { struct mv64x60_wdt_pdata *pdata = dev_get_platdata(&dev->dev); struct resource *r; int timeout = 10; bus_clk = 133; /* in MHz */ if (pdata) { timeout = pdata->timeout; bus_clk = pdata->bus_clk; } /* Since bus_clk is truncated MHz, actual frequency could be * up to 1MHz higher. Round up, since it's better to time out * too late than too soon. */ bus_clk++; bus_clk *= 1000000; /* convert to Hz */ r = platform_get_resource(dev, IORESOURCE_MEM, 0); if (!r) return -ENODEV; mv64x60_wdt_regs = devm_ioremap(&dev->dev, r->start, resource_size(r)); if (mv64x60_wdt_regs == NULL) return -ENOMEM; mv64x60_wdt_set_timeout(timeout); mv64x60_wdt_handler_disable(); /* in case timer was already running */ return misc_register(&mv64x60_wdt_miscdev); } static int mv64x60_wdt_remove(struct platform_device *dev) { misc_deregister(&mv64x60_wdt_miscdev); mv64x60_wdt_handler_disable(); return 0; } static struct platform_driver mv64x60_wdt_driver = { .probe = mv64x60_wdt_probe, .remove = mv64x60_wdt_remove, .driver = { .name = MV64x60_WDT_NAME, }, }; static int __init mv64x60_wdt_init(void) { pr_info("MV64x60 watchdog driver\n"); return platform_driver_register(&mv64x60_wdt_driver); } static void __exit mv64x60_wdt_exit(void) { platform_driver_unregister(&mv64x60_wdt_driver); } module_init(mv64x60_wdt_init); module_exit(mv64x60_wdt_exit); MODULE_AUTHOR("James Chapman "); MODULE_DESCRIPTION("MV64x60 watchdog driver"); MODULE_LICENSE("GPL"); MODULE_ALIAS("platform:" MV64x60_WDT_NAME);