diff options
Diffstat (limited to 'drivers/watchdog/mv64x60_wdt.c')
| -rw-r--r-- | drivers/watchdog/mv64x60_wdt.c | 325 |
1 files changed, 325 insertions, 0 deletions
diff --git a/drivers/watchdog/mv64x60_wdt.c b/drivers/watchdog/mv64x60_wdt.c new file mode 100644 index 000000000..315275d7b --- /dev/null +++ b/drivers/watchdog/mv64x60_wdt.c @@ -0,0 +1,325 @@ +/* + * mv64x60_wdt.c - MV64X60 (Marvell Discovery) watchdog userspace interface + * + * Author: James Chapman <jchapman@katalix.com> + * + * 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 <jolt@tuxbox.org> 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 <linux/fs.h> +#include <linux/init.h> +#include <linux/kernel.h> +#include <linux/miscdevice.h> +#include <linux/module.h> +#include <linux/watchdog.h> +#include <linux/platform_device.h> +#include <linux/mv643xx.h> +#include <linux/uaccess.h> +#include <linux/io.h> + +#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 nonseekable_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 <jchapman@katalix.com>"); +MODULE_DESCRIPTION("MV64x60 watchdog driver"); +MODULE_LICENSE("GPL"); +MODULE_ALIAS("platform:" MV64x60_WDT_NAME); |