diff options
Diffstat (limited to 'drivers/watchdog/gef_wdt.c')
| -rw-r--r-- | drivers/watchdog/gef_wdt.c | 333 |
1 files changed, 333 insertions, 0 deletions
diff --git a/drivers/watchdog/gef_wdt.c b/drivers/watchdog/gef_wdt.c new file mode 100644 index 00000000..17f4cae7 --- /dev/null +++ b/drivers/watchdog/gef_wdt.c @@ -0,0 +1,333 @@ +/* + * GE watchdog userspace interface + * + * Author: Martyn Welch <martyn.welch@ge.com> + * + * 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 <jchapman@katalix.com> + */ + +/* 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 <linux/kernel.h> +#include <linux/compiler.h> +#include <linux/init.h> +#include <linux/module.h> +#include <linux/miscdevice.h> +#include <linux/watchdog.h> +#include <linux/fs.h> +#include <linux/of.h> +#include <linux/of_platform.h> +#include <linux/io.h> +#include <linux/uaccess.h> + +#include <sysdev/fsl_soc.h> + +/* + * 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 __devinit 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 __devexit 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, +}; + +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 <martyn.welch@ge.com>"); +MODULE_DESCRIPTION("GE watchdog driver"); +MODULE_LICENSE("GPL"); +MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR); +MODULE_ALIAS("platform:gef_wdt"); |