270 lines
6.3 KiB
C
270 lines
6.3 KiB
C
/*
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* txx9wdt: A Hardware Watchdog Driver for TXx9 SoCs
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*
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* Copyright (C) 2007 Atsushi Nemoto <anemo@mba.ocn.ne.jp>
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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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#include <linux/module.h>
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#include <linux/moduleparam.h>
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#include <linux/types.h>
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#include <linux/miscdevice.h>
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#include <linux/watchdog.h>
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#include <linux/fs.h>
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#include <linux/init.h>
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#include <linux/uaccess.h>
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#include <linux/platform_device.h>
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#include <linux/clk.h>
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#include <linux/err.h>
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#include <linux/io.h>
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#include <asm/txx9tmr.h>
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#define TIMER_MARGIN 60 /* Default is 60 seconds */
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static int timeout = TIMER_MARGIN; /* in seconds */
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module_param(timeout, int, 0);
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MODULE_PARM_DESC(timeout,
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"Watchdog timeout in seconds. "
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"(0<timeout<((2^" __MODULE_STRING(TXX9_TIMER_BITS) ")/(IMCLK/256)), "
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"default=" __MODULE_STRING(TIMER_MARGIN) ")");
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static int nowayout = WATCHDOG_NOWAYOUT;
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module_param(nowayout, int, 0);
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MODULE_PARM_DESC(nowayout,
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"Watchdog cannot be stopped once started "
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"(default=" __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
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#define WD_TIMER_CCD 7 /* 1/256 */
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#define WD_TIMER_CLK (clk_get_rate(txx9_imclk) / (2 << WD_TIMER_CCD))
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#define WD_MAX_TIMEOUT ((0xffffffff >> (32 - TXX9_TIMER_BITS)) / WD_TIMER_CLK)
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static unsigned long txx9wdt_alive;
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static int expect_close;
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static struct txx9_tmr_reg __iomem *txx9wdt_reg;
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static struct clk *txx9_imclk;
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static DEFINE_SPINLOCK(txx9_lock);
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static void txx9wdt_ping(void)
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{
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spin_lock(&txx9_lock);
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__raw_writel(TXx9_TMWTMR_TWIE | TXx9_TMWTMR_TWC, &txx9wdt_reg->wtmr);
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spin_unlock(&txx9_lock);
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}
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static void txx9wdt_start(void)
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{
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spin_lock(&txx9_lock);
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__raw_writel(WD_TIMER_CLK * timeout, &txx9wdt_reg->cpra);
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__raw_writel(WD_TIMER_CCD, &txx9wdt_reg->ccdr);
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__raw_writel(0, &txx9wdt_reg->tisr); /* clear pending interrupt */
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__raw_writel(TXx9_TMTCR_TCE | TXx9_TMTCR_CCDE | TXx9_TMTCR_TMODE_WDOG,
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&txx9wdt_reg->tcr);
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__raw_writel(TXx9_TMWTMR_TWIE | TXx9_TMWTMR_TWC, &txx9wdt_reg->wtmr);
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spin_unlock(&txx9_lock);
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}
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static void txx9wdt_stop(void)
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{
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spin_lock(&txx9_lock);
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__raw_writel(TXx9_TMWTMR_WDIS, &txx9wdt_reg->wtmr);
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__raw_writel(__raw_readl(&txx9wdt_reg->tcr) & ~TXx9_TMTCR_TCE,
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&txx9wdt_reg->tcr);
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spin_unlock(&txx9_lock);
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}
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static int txx9wdt_open(struct inode *inode, struct file *file)
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{
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if (test_and_set_bit(0, &txx9wdt_alive))
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return -EBUSY;
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if (__raw_readl(&txx9wdt_reg->tcr) & TXx9_TMTCR_TCE) {
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clear_bit(0, &txx9wdt_alive);
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return -EBUSY;
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}
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if (nowayout)
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__module_get(THIS_MODULE);
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txx9wdt_start();
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return nonseekable_open(inode, file);
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}
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static int txx9wdt_release(struct inode *inode, struct file *file)
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{
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if (expect_close)
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txx9wdt_stop();
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else {
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printk(KERN_CRIT "txx9wdt: "
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"Unexpected close, not stopping watchdog!\n");
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txx9wdt_ping();
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}
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clear_bit(0, &txx9wdt_alive);
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expect_close = 0;
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return 0;
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}
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static ssize_t txx9wdt_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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if (len) {
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if (!nowayout) {
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size_t i;
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expect_close = 0;
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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_close = 1;
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}
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}
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txx9wdt_ping();
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}
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return len;
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}
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static long txx9wdt_ioctl(struct file *file, unsigned int cmd,
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unsigned long arg)
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{
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void __user *argp = (void __user *)arg;
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int __user *p = argp;
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int new_timeout;
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static const struct watchdog_info ident = {
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.options = WDIOF_SETTIMEOUT |
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WDIOF_KEEPALIVEPING |
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WDIOF_MAGICCLOSE,
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.firmware_version = 0,
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.identity = "Hardware Watchdog for TXx9",
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};
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switch (cmd) {
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case WDIOC_GETSUPPORT:
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return copy_to_user(argp, &ident, sizeof(ident)) ? -EFAULT : 0;
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case WDIOC_GETSTATUS:
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case WDIOC_GETBOOTSTATUS:
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return put_user(0, p);
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case WDIOC_KEEPALIVE:
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txx9wdt_ping();
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return 0;
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case WDIOC_SETTIMEOUT:
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if (get_user(new_timeout, p))
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return -EFAULT;
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if (new_timeout < 1 || new_timeout > WD_MAX_TIMEOUT)
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return -EINVAL;
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timeout = new_timeout;
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txx9wdt_stop();
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txx9wdt_start();
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/* Fall */
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case WDIOC_GETTIMEOUT:
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return put_user(timeout, p);
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default:
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return -ENOTTY;
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}
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}
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static const struct file_operations txx9wdt_fops = {
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.owner = THIS_MODULE,
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.llseek = no_llseek,
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.write = txx9wdt_write,
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.unlocked_ioctl = txx9wdt_ioctl,
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.open = txx9wdt_open,
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.release = txx9wdt_release,
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};
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static struct miscdevice txx9wdt_miscdev = {
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.minor = WATCHDOG_MINOR,
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.name = "watchdog",
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.fops = &txx9wdt_fops,
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};
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static int __init txx9wdt_probe(struct platform_device *dev)
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{
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struct resource *res;
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int ret;
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txx9_imclk = clk_get(NULL, "imbus_clk");
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if (IS_ERR(txx9_imclk)) {
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ret = PTR_ERR(txx9_imclk);
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txx9_imclk = NULL;
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goto exit;
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}
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ret = clk_enable(txx9_imclk);
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if (ret) {
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clk_put(txx9_imclk);
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txx9_imclk = NULL;
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goto exit;
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}
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res = platform_get_resource(dev, IORESOURCE_MEM, 0);
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if (!res)
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goto exit_busy;
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if (!devm_request_mem_region(&dev->dev, res->start, resource_size(res),
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"txx9wdt"))
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goto exit_busy;
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txx9wdt_reg = devm_ioremap(&dev->dev, res->start, resource_size(res));
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if (!txx9wdt_reg)
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goto exit_busy;
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ret = misc_register(&txx9wdt_miscdev);
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if (ret) {
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goto exit;
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}
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printk(KERN_INFO "Hardware Watchdog Timer for TXx9: "
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"timeout=%d sec (max %ld) (nowayout= %d)\n",
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timeout, WD_MAX_TIMEOUT, nowayout);
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return 0;
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exit_busy:
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ret = -EBUSY;
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exit:
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if (txx9_imclk) {
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clk_disable(txx9_imclk);
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clk_put(txx9_imclk);
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}
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return ret;
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}
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static int __exit txx9wdt_remove(struct platform_device *dev)
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{
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misc_deregister(&txx9wdt_miscdev);
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clk_disable(txx9_imclk);
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clk_put(txx9_imclk);
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return 0;
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}
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static void txx9wdt_shutdown(struct platform_device *dev)
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{
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txx9wdt_stop();
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}
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static struct platform_driver txx9wdt_driver = {
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.remove = __exit_p(txx9wdt_remove),
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.shutdown = txx9wdt_shutdown,
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.driver = {
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.name = "txx9wdt",
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.owner = THIS_MODULE,
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},
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};
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static int __init watchdog_init(void)
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{
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return platform_driver_probe(&txx9wdt_driver, txx9wdt_probe);
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}
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static void __exit watchdog_exit(void)
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{
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platform_driver_unregister(&txx9wdt_driver);
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}
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module_init(watchdog_init);
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module_exit(watchdog_exit);
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MODULE_DESCRIPTION("TXx9 Watchdog Driver");
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MODULE_LICENSE("GPL");
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MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
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MODULE_ALIAS("platform:txx9wdt");
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