| /* |
| * 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_address.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 stream_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 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 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", |
| }, |
| {}, |
| }; |
| MODULE_DEVICE_TABLE(of, gef_wdt_ids); |
| |
| static struct platform_driver gef_wdt_driver = { |
| .driver = { |
| .name = "gef_wdt", |
| .of_match_table = gef_wdt_ids, |
| }, |
| .probe = gef_wdt_probe, |
| .remove = gef_wdt_remove, |
| }; |
| |
| 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("platform:gef_wdt"); |