/* * Watchdog driver for Atmel AT32AP700X devices * * Copyright (C) 2005-2006 Atmel Corporation * * This program is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License version 2 as * published by the Free Software Foundation. * * * Errata: WDT Clear is blocked after WDT Reset * * A watchdog timer event will, after reset, block writes to the WDT_CLEAR * register, preventing the program to clear the next Watchdog Timer Reset. * * If you still want to use the WDT after a WDT reset a small code can be * insterted at the startup checking the AVR32_PM.rcause register for WDT reset * and use a GPIO pin to reset the system. This method requires that one of the * GPIO pins are available and connected externally to the RESET_N pin. After * the GPIO pin has pulled down the reset line the GPIO will be reset and leave * the pin tristated with pullup. */ #include <linux/init.h> #include <linux/kernel.h> #include <linux/module.h> #include <linux/moduleparam.h> #include <linux/miscdevice.h> #include <linux/fs.h> #include <linux/platform_device.h> #include <linux/watchdog.h> #include <linux/uaccess.h> #include <linux/io.h> #include <linux/spinlock.h> #include <linux/slab.h> #define TIMEOUT_MIN 1 #define TIMEOUT_MAX 2 #define TIMEOUT_DEFAULT TIMEOUT_MAX /* module parameters */ static int timeout = TIMEOUT_DEFAULT; module_param(timeout, int, 0); MODULE_PARM_DESC(timeout, "Timeout value. Limited to be 1 or 2 seconds. (default=" __MODULE_STRING(TIMEOUT_DEFAULT) ")"); 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) ")"); /* Watchdog registers and write/read macro */ #define WDT_CTRL 0x00 #define WDT_CTRL_EN 0 #define WDT_CTRL_PSEL 8 #define WDT_CTRL_KEY 24 #define WDT_CLR 0x04 #define WDT_RCAUSE 0x10 #define WDT_RCAUSE_POR 0 #define WDT_RCAUSE_EXT 2 #define WDT_RCAUSE_WDT 3 #define WDT_RCAUSE_JTAG 4 #define WDT_RCAUSE_SERP 5 #define WDT_BIT(name) (1 << WDT_##name) #define WDT_BF(name, value) ((value) << WDT_##name) #define wdt_readl(dev, reg) \ __raw_readl((dev)->regs + WDT_##reg) #define wdt_writel(dev, reg, value) \ __raw_writel((value), (dev)->regs + WDT_##reg) struct wdt_at32ap700x { void __iomem *regs; spinlock_t io_lock; int timeout; int boot_status; unsigned long users; struct miscdevice miscdev; }; static struct wdt_at32ap700x *wdt; static char expect_release; /* * Disable the watchdog. */ static inline void at32_wdt_stop(void) { unsigned long psel; spin_lock(&wdt->io_lock); psel = wdt_readl(wdt, CTRL) & WDT_BF(CTRL_PSEL, 0x0f); wdt_writel(wdt, CTRL, psel | WDT_BF(CTRL_KEY, 0x55)); wdt_writel(wdt, CTRL, psel | WDT_BF(CTRL_KEY, 0xaa)); spin_unlock(&wdt->io_lock); } /* * Enable and reset the watchdog. */ static inline void at32_wdt_start(void) { /* 0xf is 2^16 divider = 2 sec, 0xe is 2^15 divider = 1 sec */ unsigned long psel = (wdt->timeout > 1) ? 0xf : 0xe; spin_lock(&wdt->io_lock); wdt_writel(wdt, CTRL, WDT_BIT(CTRL_EN) | WDT_BF(CTRL_PSEL, psel) | WDT_BF(CTRL_KEY, 0x55)); wdt_writel(wdt, CTRL, WDT_BIT(CTRL_EN) | WDT_BF(CTRL_PSEL, psel) | WDT_BF(CTRL_KEY, 0xaa)); spin_unlock(&wdt->io_lock); } /* * Pat the watchdog timer. */ static inline void at32_wdt_pat(void) { spin_lock(&wdt->io_lock); wdt_writel(wdt, CLR, 0x42); spin_unlock(&wdt->io_lock); } /* * Watchdog device is opened, and watchdog starts running. */ static int at32_wdt_open(struct inode *inode, struct file *file) { if (test_and_set_bit(1, &wdt->users)) return -EBUSY; at32_wdt_start(); return nonseekable_open(inode, file); } /* * Close the watchdog device. */ static int at32_wdt_close(struct inode *inode, struct file *file) { if (expect_release == 42) { at32_wdt_stop(); } else { dev_dbg(wdt->miscdev.parent, "unexpected close, not stopping watchdog!\n"); at32_wdt_pat(); } clear_bit(1, &wdt->users); expect_release = 0; return 0; } /* * Change the watchdog time interval. */ static int at32_wdt_settimeout(int time) { /* * All counting occurs at 1 / SLOW_CLOCK (32 kHz) and max prescaler is * 2 ^ 16 allowing up to 2 seconds timeout. */ if ((time < TIMEOUT_MIN) || (time > TIMEOUT_MAX)) return -EINVAL; /* * Set new watchdog time. It will be used when at32_wdt_start() is * called. */ wdt->timeout = time; return 0; } /* * Get the watchdog status. */ static int at32_wdt_get_status(void) { int rcause; int status = 0; rcause = wdt_readl(wdt, RCAUSE); switch (rcause) { case WDT_BIT(RCAUSE_EXT): status = WDIOF_EXTERN1; break; case WDT_BIT(RCAUSE_WDT): status = WDIOF_CARDRESET; break; case WDT_BIT(RCAUSE_POR): /* fall through */ case WDT_BIT(RCAUSE_JTAG): /* fall through */ case WDT_BIT(RCAUSE_SERP): /* fall through */ default: break; } return status; } static const struct watchdog_info at32_wdt_info = { .identity = "at32ap700x watchdog", .options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE, }; /* * Handle commands from user-space. */ static long at32_wdt_ioctl(struct file *file, unsigned int cmd, unsigned long arg) { int ret = -ENOTTY; int time; void __user *argp = (void __user *)arg; int __user *p = argp; switch (cmd) { case WDIOC_GETSUPPORT: ret = copy_to_user(argp, &at32_wdt_info, sizeof(at32_wdt_info)) ? -EFAULT : 0; break; case WDIOC_GETSTATUS: ret = put_user(0, p); break; case WDIOC_GETBOOTSTATUS: ret = put_user(wdt->boot_status, p); break; case WDIOC_SETOPTIONS: ret = get_user(time, p); if (ret) break; if (time & WDIOS_DISABLECARD) at32_wdt_stop(); if (time & WDIOS_ENABLECARD) at32_wdt_start(); ret = 0; break; case WDIOC_KEEPALIVE: at32_wdt_pat(); ret = 0; break; case WDIOC_SETTIMEOUT: ret = get_user(time, p); if (ret) break; ret = at32_wdt_settimeout(time); if (ret) break; /* Enable new time value */ at32_wdt_start(); /* fall through */ case WDIOC_GETTIMEOUT: ret = put_user(wdt->timeout, p); break; } return ret; } static ssize_t at32_wdt_write(struct file *file, const char __user *data, size_t len, loff_t *ppos) { /* See if we got the magic character 'V' and reload the timer */ if (len) { if (!nowayout) { size_t i; /* * note: just in case someone wrote the magic * character five months ago... */ expect_release = 0; /* * scan to see whether or not we got the magic * character */ for (i = 0; i != len; i++) { char c; if (get_user(c, data + i)) return -EFAULT; if (c == 'V') expect_release = 42; } } /* someone wrote to us, we should pat the watchdog */ at32_wdt_pat(); } return len; } static const struct file_operations at32_wdt_fops = { .owner = THIS_MODULE, .llseek = no_llseek, .unlocked_ioctl = at32_wdt_ioctl, .open = at32_wdt_open, .release = at32_wdt_close, .write = at32_wdt_write, }; static int __init at32_wdt_probe(struct platform_device *pdev) { struct resource *regs; int ret; if (wdt) { dev_dbg(&pdev->dev, "only 1 wdt instance supported.\n"); return -EBUSY; } regs = platform_get_resource(pdev, IORESOURCE_MEM, 0); if (!regs) { dev_dbg(&pdev->dev, "missing mmio resource\n"); return -ENXIO; } wdt = devm_kzalloc(&pdev->dev, sizeof(struct wdt_at32ap700x), GFP_KERNEL); if (!wdt) return -ENOMEM; wdt->regs = devm_ioremap(&pdev->dev, regs->start, resource_size(regs)); if (!wdt->regs) { ret = -ENOMEM; dev_dbg(&pdev->dev, "could not map I/O memory\n"); goto err_free; } spin_lock_init(&wdt->io_lock); wdt->boot_status = at32_wdt_get_status(); /* Work-around for watchdog silicon errata. */ if (wdt->boot_status & WDIOF_CARDRESET) { dev_info(&pdev->dev, "CPU must be reset with external " "reset or POR due to silicon errata.\n"); ret = -EIO; goto err_free; } else { wdt->users = 0; } wdt->miscdev.minor = WATCHDOG_MINOR; wdt->miscdev.name = "watchdog"; wdt->miscdev.fops = &at32_wdt_fops; wdt->miscdev.parent = &pdev->dev; platform_set_drvdata(pdev, wdt); if (at32_wdt_settimeout(timeout)) { at32_wdt_settimeout(TIMEOUT_DEFAULT); dev_dbg(&pdev->dev, "default timeout invalid, set to %d sec.\n", TIMEOUT_DEFAULT); } ret = misc_register(&wdt->miscdev); if (ret) { dev_dbg(&pdev->dev, "failed to register wdt miscdev\n"); goto err_free; } dev_info(&pdev->dev, "AT32AP700X WDT at 0x%p, timeout %d sec (nowayout=%d)\n", wdt->regs, wdt->timeout, nowayout); return 0; err_free: wdt = NULL; return ret; } static int __exit at32_wdt_remove(struct platform_device *pdev) { if (wdt && platform_get_drvdata(pdev) == wdt) { /* Stop the timer before we leave */ if (!nowayout) at32_wdt_stop(); misc_deregister(&wdt->miscdev); wdt = NULL; } return 0; } static void at32_wdt_shutdown(struct platform_device *pdev) { at32_wdt_stop(); } #ifdef CONFIG_PM static int at32_wdt_suspend(struct platform_device *pdev, pm_message_t message) { at32_wdt_stop(); return 0; } static int at32_wdt_resume(struct platform_device *pdev) { if (wdt->users) at32_wdt_start(); return 0; } #else #define at32_wdt_suspend NULL #define at32_wdt_resume NULL #endif /* work with hotplug and coldplug */ MODULE_ALIAS("platform:at32_wdt"); static struct platform_driver at32_wdt_driver = { .remove = __exit_p(at32_wdt_remove), .suspend = at32_wdt_suspend, .resume = at32_wdt_resume, .driver = { .name = "at32_wdt", }, .shutdown = at32_wdt_shutdown, }; module_platform_driver_probe(at32_wdt_driver, at32_wdt_probe); MODULE_AUTHOR("Hans-Christian Egtvedt <egtvedt@samfundet.no>"); MODULE_DESCRIPTION("Watchdog driver for Atmel AT32AP700X"); MODULE_LICENSE("GPL");