diff options
Diffstat (limited to 'drivers/watchdog/at32ap700x_wdt.c')
| -rw-r--r-- | drivers/watchdog/at32ap700x_wdt.c | 454 |
1 files changed, 454 insertions, 0 deletions
diff --git a/drivers/watchdog/at32ap700x_wdt.c b/drivers/watchdog/at32ap700x_wdt.c new file mode 100644 index 00000000..2896430c --- /dev/null +++ b/drivers/watchdog/at32ap700x_wdt.c @@ -0,0 +1,454 @@ +/* + * 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 = kzalloc(sizeof(struct wdt_at32ap700x), GFP_KERNEL); + if (!wdt) { + dev_dbg(&pdev->dev, "no memory for wdt structure\n"); + return -ENOMEM; + } + + wdt->regs = ioremap(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_iounmap; + } 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_register; + } + + dev_info(&pdev->dev, + "AT32AP700X WDT at 0x%p, timeout %d sec (nowayout=%d)\n", + wdt->regs, wdt->timeout, nowayout); + + return 0; + +err_register: + platform_set_drvdata(pdev, NULL); +err_iounmap: + iounmap(wdt->regs); +err_free: + kfree(wdt); + 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); + iounmap(wdt->regs); + kfree(wdt); + wdt = NULL; + platform_set_drvdata(pdev, 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", + .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 <egtvedt@samfundet.no>"); +MODULE_DESCRIPTION("Watchdog driver for Atmel AT32AP700X"); +MODULE_LICENSE("GPL"); +MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR); |