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