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The Nuvoton NPCM750 has a watchdog implemented as a single register inside the timer peripheral. This driver exposes that watchdog as a standard watchdog device with coarse timeout intervals, limited by the combination of prescaler and counter that is provided by the hardware. The calculation is taken from the Nuvoton vendor tree. The watchdog is left running if a bootloader had it going. The rate is the one specified in the device tree, or the default value (obtained from the datasheet). There is a pre-timeout IRQ that is wired up. This timeout always occurs 1024 clocks before the timeout. Signed-off-by: Joel Stanley <joel@jms.id.au> Reviewed-by: Guenter Roeck <linux@roeck-us.net> Signed-off-by: Guenter Roeck <linux@roeck-us.net> Signed-off-by: Wim Van Sebroeck <wim@iguana.be>
255 lines
5.7 KiB
C
255 lines
5.7 KiB
C
// SPDX-License-Identifier: GPL-2.0
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// Copyright (c) 2018 Nuvoton Technology corporation.
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// Copyright (c) 2018 IBM Corp.
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#include <linux/bitops.h>
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#include <linux/delay.h>
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#include <linux/interrupt.h>
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#include <linux/kernel.h>
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#include <linux/module.h>
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#include <linux/of_irq.h>
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#include <linux/platform_device.h>
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#include <linux/slab.h>
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#include <linux/watchdog.h>
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#define NPCM_WTCR 0x1C
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#define NPCM_WTCLK (BIT(10) | BIT(11)) /* Clock divider */
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#define NPCM_WTE BIT(7) /* Enable */
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#define NPCM_WTIE BIT(6) /* Enable irq */
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#define NPCM_WTIS (BIT(4) | BIT(5)) /* Interval selection */
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#define NPCM_WTIF BIT(3) /* Interrupt flag*/
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#define NPCM_WTRF BIT(2) /* Reset flag */
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#define NPCM_WTRE BIT(1) /* Reset enable */
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#define NPCM_WTR BIT(0) /* Reset counter */
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/*
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* Watchdog timeouts
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*
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* 170 msec: WTCLK=01 WTIS=00 VAL= 0x400
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* 670 msec: WTCLK=01 WTIS=01 VAL= 0x410
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* 1360 msec: WTCLK=10 WTIS=00 VAL= 0x800
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* 2700 msec: WTCLK=01 WTIS=10 VAL= 0x420
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* 5360 msec: WTCLK=10 WTIS=01 VAL= 0x810
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* 10700 msec: WTCLK=01 WTIS=11 VAL= 0x430
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* 21600 msec: WTCLK=10 WTIS=10 VAL= 0x820
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* 43000 msec: WTCLK=11 WTIS=00 VAL= 0xC00
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* 85600 msec: WTCLK=10 WTIS=11 VAL= 0x830
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* 172000 msec: WTCLK=11 WTIS=01 VAL= 0xC10
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* 687000 msec: WTCLK=11 WTIS=10 VAL= 0xC20
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* 2750000 msec: WTCLK=11 WTIS=11 VAL= 0xC30
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*/
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struct npcm_wdt {
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struct watchdog_device wdd;
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void __iomem *reg;
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};
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static inline struct npcm_wdt *to_npcm_wdt(struct watchdog_device *wdd)
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{
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return container_of(wdd, struct npcm_wdt, wdd);
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}
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static int npcm_wdt_ping(struct watchdog_device *wdd)
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{
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struct npcm_wdt *wdt = to_npcm_wdt(wdd);
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u32 val;
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val = readl(wdt->reg);
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writel(val | NPCM_WTR, wdt->reg);
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return 0;
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}
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static int npcm_wdt_start(struct watchdog_device *wdd)
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{
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struct npcm_wdt *wdt = to_npcm_wdt(wdd);
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u32 val;
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if (wdd->timeout < 2)
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val = 0x800;
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else if (wdd->timeout < 3)
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val = 0x420;
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else if (wdd->timeout < 6)
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val = 0x810;
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else if (wdd->timeout < 11)
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val = 0x430;
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else if (wdd->timeout < 22)
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val = 0x820;
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else if (wdd->timeout < 44)
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val = 0xC00;
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else if (wdd->timeout < 87)
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val = 0x830;
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else if (wdd->timeout < 173)
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val = 0xC10;
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else if (wdd->timeout < 688)
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val = 0xC20;
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else
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val = 0xC30;
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val |= NPCM_WTRE | NPCM_WTE | NPCM_WTR | NPCM_WTIE;
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writel(val, wdt->reg);
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return 0;
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}
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static int npcm_wdt_stop(struct watchdog_device *wdd)
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{
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struct npcm_wdt *wdt = to_npcm_wdt(wdd);
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writel(0, wdt->reg);
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return 0;
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}
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static int npcm_wdt_set_timeout(struct watchdog_device *wdd,
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unsigned int timeout)
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{
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if (timeout < 2)
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wdd->timeout = 1;
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else if (timeout < 3)
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wdd->timeout = 2;
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else if (timeout < 6)
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wdd->timeout = 5;
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else if (timeout < 11)
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wdd->timeout = 10;
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else if (timeout < 22)
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wdd->timeout = 21;
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else if (timeout < 44)
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wdd->timeout = 43;
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else if (timeout < 87)
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wdd->timeout = 86;
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else if (timeout < 173)
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wdd->timeout = 172;
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else if (timeout < 688)
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wdd->timeout = 687;
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else
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wdd->timeout = 2750;
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if (watchdog_active(wdd))
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npcm_wdt_start(wdd);
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return 0;
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}
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static irqreturn_t npcm_wdt_interrupt(int irq, void *data)
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{
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struct npcm_wdt *wdt = data;
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watchdog_notify_pretimeout(&wdt->wdd);
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return IRQ_HANDLED;
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}
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static int npcm_wdt_restart(struct watchdog_device *wdd,
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unsigned long action, void *data)
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{
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struct npcm_wdt *wdt = to_npcm_wdt(wdd);
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writel(NPCM_WTR | NPCM_WTRE | NPCM_WTE, wdt->reg);
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udelay(1000);
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return 0;
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}
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static bool npcm_is_running(struct watchdog_device *wdd)
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{
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struct npcm_wdt *wdt = to_npcm_wdt(wdd);
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return readl(wdt->reg) & NPCM_WTE;
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}
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static const struct watchdog_info npcm_wdt_info = {
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.identity = KBUILD_MODNAME,
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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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static const struct watchdog_ops npcm_wdt_ops = {
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.owner = THIS_MODULE,
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.start = npcm_wdt_start,
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.stop = npcm_wdt_stop,
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.ping = npcm_wdt_ping,
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.set_timeout = npcm_wdt_set_timeout,
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.restart = npcm_wdt_restart,
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};
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static int npcm_wdt_probe(struct platform_device *pdev)
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{
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struct device *dev = &pdev->dev;
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struct npcm_wdt *wdt;
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struct resource *res;
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int irq;
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int ret;
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wdt = devm_kzalloc(&pdev->dev, sizeof(*wdt), GFP_KERNEL);
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if (!wdt)
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return -ENOMEM;
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res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
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wdt->reg = devm_ioremap_resource(dev, res);
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if (IS_ERR(wdt->reg))
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return PTR_ERR(wdt->reg);
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irq = platform_get_irq(pdev, 0);
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if (irq < 0)
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return irq;
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wdt->wdd.info = &npcm_wdt_info;
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wdt->wdd.ops = &npcm_wdt_ops;
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wdt->wdd.min_timeout = 1;
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wdt->wdd.max_timeout = 2750;
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wdt->wdd.parent = dev;
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wdt->wdd.timeout = 86;
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watchdog_init_timeout(&wdt->wdd, 0, dev);
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/* Ensure timeout is able to be represented by the hardware */
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npcm_wdt_set_timeout(&wdt->wdd, wdt->wdd.timeout);
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if (npcm_is_running(&wdt->wdd)) {
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/* Restart with the default or device-tree specified timeout */
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npcm_wdt_start(&wdt->wdd);
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set_bit(WDOG_HW_RUNNING, &wdt->wdd.status);
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}
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ret = devm_request_irq(dev, irq, npcm_wdt_interrupt, 0,
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"watchdog", wdt);
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if (ret)
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return ret;
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ret = devm_watchdog_register_device(dev, &wdt->wdd);
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if (ret) {
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dev_err(dev, "failed to register watchdog\n");
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return ret;
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}
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dev_info(dev, "NPCM watchdog driver enabled\n");
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return 0;
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}
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#ifdef CONFIG_OF
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static const struct of_device_id npcm_wdt_match[] = {
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{.compatible = "nuvoton,npcm750-wdt"},
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{},
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};
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MODULE_DEVICE_TABLE(of, npcm_wdt_match);
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#endif
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static struct platform_driver npcm_wdt_driver = {
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.probe = npcm_wdt_probe,
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.driver = {
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.name = "npcm-wdt",
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.of_match_table = of_match_ptr(npcm_wdt_match),
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},
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};
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module_platform_driver(npcm_wdt_driver);
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MODULE_AUTHOR("Joel Stanley");
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MODULE_DESCRIPTION("Watchdog driver for NPCM");
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MODULE_LICENSE("GPL v2");
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