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drivers/watchdog/at32ap700x_wdt.c
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/* * 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. |
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* * * 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. |
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*/ #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> |
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#include <linux/uaccess.h> #include <linux/io.h> |
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#include <linux/spinlock.h> |
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#include <linux/slab.h> |
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#define TIMEOUT_MIN 1 |
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#define TIMEOUT_MAX 2 |
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#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) ")"); |
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static int nowayout = WATCHDOG_NOWAYOUT; module_param(nowayout, int, 0); MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default=" __MODULE_STRING(WATCHDOG_NOWAYOUT) ")"); |
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/* 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 |
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#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 |
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#define WDT_BIT(name) (1 << WDT_##name) |
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#define WDT_BF(name, value) ((value) << WDT_##name) |
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|
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#define wdt_readl(dev, reg) \ |
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__raw_readl((dev)->regs + WDT_##reg) |
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#define wdt_writel(dev, reg, value) \ |
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__raw_writel((value), (dev)->regs + WDT_##reg) struct wdt_at32ap700x { void __iomem *regs; |
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spinlock_t io_lock; |
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int timeout; |
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int boot_status; |
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unsigned long users; |
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struct miscdevice miscdev; }; static struct wdt_at32ap700x *wdt; |
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static char expect_release; |
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/* * Disable the watchdog. */ |
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static inline void at32_wdt_stop(void) |
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{ |
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unsigned long psel; |
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spin_lock(&wdt->io_lock); |
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psel = wdt_readl(wdt, CTRL) & WDT_BF(CTRL_PSEL, 0x0f); |
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wdt_writel(wdt, CTRL, psel | WDT_BF(CTRL_KEY, 0x55)); wdt_writel(wdt, CTRL, psel | WDT_BF(CTRL_KEY, 0xaa)); |
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spin_unlock(&wdt->io_lock); |
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} /* * Enable and reset the watchdog. */ |
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static inline void at32_wdt_start(void) |
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{ /* 0xf is 2^16 divider = 2 sec, 0xe is 2^15 divider = 1 sec */ unsigned long psel = (wdt->timeout > 1) ? 0xf : 0xe; |
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spin_lock(&wdt->io_lock); |
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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)); |
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spin_unlock(&wdt->io_lock); |
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} /* * Pat the watchdog timer. */ |
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static inline void at32_wdt_pat(void) |
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{ |
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spin_lock(&wdt->io_lock); |
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wdt_writel(wdt, CLR, 0x42); |
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spin_unlock(&wdt->io_lock); |
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} /* * 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); } /* |
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* Close the watchdog device. |
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*/ static int at32_wdt_close(struct inode *inode, struct file *file) { |
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if (expect_release == 42) { at32_wdt_stop(); } else { dev_dbg(wdt->miscdev.parent, |
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"unexpected close, not stopping watchdog! "); |
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at32_wdt_pat(); } |
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clear_bit(1, &wdt->users); |
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expect_release = 0; |
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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; |
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/* * Set new watchdog time. It will be used when at32_wdt_start() is * called. */ |
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wdt->timeout = time; return 0; } |
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/* * 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; } |
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static const struct watchdog_info at32_wdt_info = { |
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.identity = "at32ap700x watchdog", |
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.options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE, |
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}; /* * Handle commands from user-space. */ |
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static long at32_wdt_ioctl(struct file *file, unsigned int cmd, unsigned long arg) |
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{ int ret = -ENOTTY; int time; void __user *argp = (void __user *)arg; int __user *p = argp; |
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switch (cmd) { |
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case WDIOC_GETSUPPORT: ret = copy_to_user(argp, &at32_wdt_info, sizeof(at32_wdt_info)) ? -EFAULT : 0; break; |
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case WDIOC_GETSTATUS: |
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ret = put_user(0, p); break; |
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case WDIOC_GETBOOTSTATUS: ret = put_user(wdt->boot_status, p); break; |
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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; |
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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; |
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} return ret; } |
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static ssize_t at32_wdt_write(struct file *file, const char __user *data, size_t len, loff_t *ppos) |
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{ |
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/* 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; |
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if (get_user(c, data + i)) |
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return -EFAULT; if (c == 'V') expect_release = 42; } } /* someone wrote to us, we should pat the watchdog */ at32_wdt_pat(); } |
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return len; } static const struct file_operations at32_wdt_fops = { .owner = THIS_MODULE, .llseek = no_llseek, |
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.unlocked_ioctl = at32_wdt_ioctl, |
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.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. "); return -EBUSY; } regs = platform_get_resource(pdev, IORESOURCE_MEM, 0); if (!regs) { dev_dbg(&pdev->dev, "missing mmio resource "); return -ENXIO; } wdt = kzalloc(sizeof(struct wdt_at32ap700x), GFP_KERNEL); if (!wdt) { dev_dbg(&pdev->dev, "no memory for wdt structure "); return -ENOMEM; } |
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wdt->regs = ioremap(regs->start, resource_size(regs)); |
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if (!wdt->regs) { ret = -ENOMEM; dev_dbg(&pdev->dev, "could not map I/O memory "); goto err_free; } |
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|
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spin_lock_init(&wdt->io_lock); |
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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. "); ret = -EIO; goto err_iounmap; } else { wdt->users = 0; } |
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wdt->miscdev.minor = WATCHDOG_MINOR; wdt->miscdev.name = "watchdog"; wdt->miscdev.fops = &at32_wdt_fops; |
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if (at32_wdt_settimeout(timeout)) { at32_wdt_settimeout(TIMEOUT_DEFAULT); |
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dev_dbg(&pdev->dev, "default timeout invalid, set to %d sec. ", |
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TIMEOUT_DEFAULT); |
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} ret = misc_register(&wdt->miscdev); if (ret) { dev_dbg(&pdev->dev, "failed to register wdt miscdev "); |
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goto err_iounmap; |
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} platform_set_drvdata(pdev, wdt); wdt->miscdev.parent = &pdev->dev; |
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dev_info(&pdev->dev, "AT32AP700X WDT at 0x%p, timeout %d sec (nowayout=%d) ", wdt->regs, wdt->timeout, nowayout); |
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return 0; |
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err_iounmap: iounmap(wdt->regs); err_free: |
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kfree(wdt); wdt = NULL; return ret; } static int __exit at32_wdt_remove(struct platform_device *pdev) { if (wdt && platform_get_drvdata(pdev) == wdt) { |
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/* Stop the timer before we leave */ if (!nowayout) at32_wdt_stop(); |
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misc_deregister(&wdt->miscdev); |
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iounmap(wdt->regs); |
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kfree(wdt); wdt = NULL; platform_set_drvdata(pdev, NULL); } |
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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; } |
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#else #define at32_wdt_suspend NULL #define at32_wdt_resume NULL |
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#endif |
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/* work with hotplug and coldplug */ MODULE_ALIAS("platform:at32_wdt"); |
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static struct platform_driver at32_wdt_driver = { .remove = __exit_p(at32_wdt_remove), |
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.suspend = at32_wdt_suspend, .resume = at32_wdt_resume, |
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.driver = { .name = "at32_wdt", .owner = THIS_MODULE, }, .shutdown = at32_wdt_shutdown, }; static int __init at32_wdt_init(void) { return platform_driver_probe(&at32_wdt_driver, at32_wdt_probe); } module_init(at32_wdt_init); static void __exit at32_wdt_exit(void) { platform_driver_unregister(&at32_wdt_driver); } module_exit(at32_wdt_exit); MODULE_AUTHOR("Hans-Christian Egtvedt <hcegtvedt@atmel.com>"); MODULE_DESCRIPTION("Watchdog driver for Atmel AT32AP700X"); MODULE_LICENSE("GPL"); MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR); |