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![Sai Prakash Ranjan](/assets/img/avatar_default.png)
During suspend/resume usecases and tests, it is common to see issues such as lockups either in suspend path or resume path because of the bugs in the corresponding device driver pm handling code. In such cases, it is important that watchdog is active to make sure that we either receive a watchdog pretimeout notification or a bite causing reset instead of a hang causing us to hard reset the machine. There are good reasons as to why we need this because: * We can have a watchdog pretimeout governor set to panic in which case we can have a backtrace which would help identify the issue with the particular driver and cause a normal reboot. * Even in case where there is no pretimeout support, a watchdog bite is still useful because some firmware has debug support to dump CPU core context on watchdog bite for post-mortem analysis. * One more usecase which comes to mind is of warm reboot. In case we hard reset the target, a cold reboot could be induced resulting in lose of ddr contents thereby losing all the debug info. Currently, the watchdog pm callback just invokes the usual suspend and resume callback which do not have any special ordering in the sense that a watchdog can be suspended before the buggy device driver suspend callback and watchdog resume can happen after the buggy device driver resume callback. This would mean that the watchdog will not be active when the buggy driver cause the lockups thereby hanging the system. So to make sure this doesn't happen, move the watchdog pm to use late/early system pm callbacks which will ensure that the watchdog is suspended late and resumed early so that it can catch such issues. Signed-off-by: Sai Prakash Ranjan <saiprakash.ranjan@codeaurora.org> Reviewed-by: Guenter Roeck <linux@roeck-us.net> Reviewed-by: Douglas Anderson <dianders@chromium.org> Link: https://lore.kernel.org/r/20210310202004.1436-1-saiprakash.ranjan@codeaurora.org Signed-off-by: Guenter Roeck <linux@roeck-us.net> Signed-off-by: Wim Van Sebroeck <wim@linux-watchdog.org>
355 lines
8.1 KiB
C
355 lines
8.1 KiB
C
// SPDX-License-Identifier: GPL-2.0-only
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/* Copyright (c) 2014, The Linux Foundation. All rights reserved.
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*/
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#include <linux/bits.h>
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#include <linux/clk.h>
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#include <linux/delay.h>
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#include <linux/interrupt.h>
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#include <linux/io.h>
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#include <linux/kernel.h>
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#include <linux/module.h>
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#include <linux/of.h>
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#include <linux/platform_device.h>
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#include <linux/watchdog.h>
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#include <linux/of_device.h>
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enum wdt_reg {
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WDT_RST,
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WDT_EN,
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WDT_STS,
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WDT_BARK_TIME,
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WDT_BITE_TIME,
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};
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#define QCOM_WDT_ENABLE BIT(0)
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static const u32 reg_offset_data_apcs_tmr[] = {
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[WDT_RST] = 0x38,
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[WDT_EN] = 0x40,
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[WDT_STS] = 0x44,
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[WDT_BARK_TIME] = 0x4C,
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[WDT_BITE_TIME] = 0x5C,
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};
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static const u32 reg_offset_data_kpss[] = {
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[WDT_RST] = 0x4,
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[WDT_EN] = 0x8,
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[WDT_STS] = 0xC,
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[WDT_BARK_TIME] = 0x10,
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[WDT_BITE_TIME] = 0x14,
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};
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struct qcom_wdt_match_data {
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const u32 *offset;
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bool pretimeout;
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};
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struct qcom_wdt {
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struct watchdog_device wdd;
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unsigned long rate;
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void __iomem *base;
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const u32 *layout;
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};
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static void __iomem *wdt_addr(struct qcom_wdt *wdt, enum wdt_reg reg)
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{
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return wdt->base + wdt->layout[reg];
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}
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static inline
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struct qcom_wdt *to_qcom_wdt(struct watchdog_device *wdd)
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{
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return container_of(wdd, struct qcom_wdt, wdd);
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}
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static irqreturn_t qcom_wdt_isr(int irq, void *arg)
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{
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struct watchdog_device *wdd = arg;
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watchdog_notify_pretimeout(wdd);
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return IRQ_HANDLED;
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}
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static int qcom_wdt_start(struct watchdog_device *wdd)
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{
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struct qcom_wdt *wdt = to_qcom_wdt(wdd);
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unsigned int bark = wdd->timeout - wdd->pretimeout;
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writel(0, wdt_addr(wdt, WDT_EN));
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writel(1, wdt_addr(wdt, WDT_RST));
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writel(bark * wdt->rate, wdt_addr(wdt, WDT_BARK_TIME));
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writel(wdd->timeout * wdt->rate, wdt_addr(wdt, WDT_BITE_TIME));
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writel(QCOM_WDT_ENABLE, wdt_addr(wdt, WDT_EN));
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return 0;
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}
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static int qcom_wdt_stop(struct watchdog_device *wdd)
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{
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struct qcom_wdt *wdt = to_qcom_wdt(wdd);
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writel(0, wdt_addr(wdt, WDT_EN));
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return 0;
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}
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static int qcom_wdt_ping(struct watchdog_device *wdd)
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{
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struct qcom_wdt *wdt = to_qcom_wdt(wdd);
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writel(1, wdt_addr(wdt, WDT_RST));
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return 0;
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}
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static int qcom_wdt_set_timeout(struct watchdog_device *wdd,
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unsigned int timeout)
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{
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wdd->timeout = timeout;
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return qcom_wdt_start(wdd);
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}
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static int qcom_wdt_set_pretimeout(struct watchdog_device *wdd,
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unsigned int timeout)
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{
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wdd->pretimeout = timeout;
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return qcom_wdt_start(wdd);
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}
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static int qcom_wdt_restart(struct watchdog_device *wdd, unsigned long action,
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void *data)
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{
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struct qcom_wdt *wdt = to_qcom_wdt(wdd);
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u32 timeout;
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/*
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* Trigger watchdog bite:
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* Setup BITE_TIME to be 128ms, and enable WDT.
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*/
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timeout = 128 * wdt->rate / 1000;
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writel(0, wdt_addr(wdt, WDT_EN));
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writel(1, wdt_addr(wdt, WDT_RST));
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writel(timeout, wdt_addr(wdt, WDT_BARK_TIME));
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writel(timeout, wdt_addr(wdt, WDT_BITE_TIME));
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writel(QCOM_WDT_ENABLE, wdt_addr(wdt, WDT_EN));
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/*
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* Actually make sure the above sequence hits hardware before sleeping.
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*/
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wmb();
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mdelay(150);
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return 0;
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}
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static int qcom_wdt_is_running(struct watchdog_device *wdd)
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{
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struct qcom_wdt *wdt = to_qcom_wdt(wdd);
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return (readl(wdt_addr(wdt, WDT_EN)) & QCOM_WDT_ENABLE);
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}
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static const struct watchdog_ops qcom_wdt_ops = {
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.start = qcom_wdt_start,
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.stop = qcom_wdt_stop,
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.ping = qcom_wdt_ping,
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.set_timeout = qcom_wdt_set_timeout,
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.set_pretimeout = qcom_wdt_set_pretimeout,
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.restart = qcom_wdt_restart,
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.owner = THIS_MODULE,
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};
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static const struct watchdog_info qcom_wdt_info = {
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.options = WDIOF_KEEPALIVEPING
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| WDIOF_MAGICCLOSE
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| WDIOF_SETTIMEOUT
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| WDIOF_CARDRESET,
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.identity = KBUILD_MODNAME,
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};
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static const struct watchdog_info qcom_wdt_pt_info = {
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.options = WDIOF_KEEPALIVEPING
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| WDIOF_MAGICCLOSE
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| WDIOF_SETTIMEOUT
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| WDIOF_PRETIMEOUT
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| WDIOF_CARDRESET,
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.identity = KBUILD_MODNAME,
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};
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static void qcom_clk_disable_unprepare(void *data)
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{
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clk_disable_unprepare(data);
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}
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static const struct qcom_wdt_match_data match_data_apcs_tmr = {
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.offset = reg_offset_data_apcs_tmr,
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.pretimeout = false,
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};
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static const struct qcom_wdt_match_data match_data_kpss = {
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.offset = reg_offset_data_kpss,
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.pretimeout = true,
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};
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static int qcom_wdt_probe(struct platform_device *pdev)
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{
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struct device *dev = &pdev->dev;
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struct qcom_wdt *wdt;
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struct resource *res;
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struct device_node *np = dev->of_node;
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const struct qcom_wdt_match_data *data;
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u32 percpu_offset;
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int irq, ret;
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struct clk *clk;
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data = of_device_get_match_data(dev);
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if (!data) {
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dev_err(dev, "Unsupported QCOM WDT module\n");
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return -ENODEV;
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}
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wdt = devm_kzalloc(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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if (!res)
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return -ENOMEM;
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/* We use CPU0's DGT for the watchdog */
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if (of_property_read_u32(np, "cpu-offset", &percpu_offset))
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percpu_offset = 0;
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res->start += percpu_offset;
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res->end += percpu_offset;
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wdt->base = devm_ioremap_resource(dev, res);
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if (IS_ERR(wdt->base))
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return PTR_ERR(wdt->base);
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clk = devm_clk_get(dev, NULL);
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if (IS_ERR(clk)) {
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dev_err(dev, "failed to get input clock\n");
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return PTR_ERR(clk);
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}
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ret = clk_prepare_enable(clk);
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if (ret) {
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dev_err(dev, "failed to setup clock\n");
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return ret;
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}
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ret = devm_add_action_or_reset(dev, qcom_clk_disable_unprepare, clk);
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if (ret)
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return ret;
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/*
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* We use the clock rate to calculate the max timeout, so ensure it's
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* not zero to avoid a divide-by-zero exception.
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*
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* WATCHDOG_CORE assumes units of seconds, if the WDT is clocked such
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* that it would bite before a second elapses it's usefulness is
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* limited. Bail if this is the case.
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*/
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wdt->rate = clk_get_rate(clk);
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if (wdt->rate == 0 ||
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wdt->rate > 0x10000000U) {
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dev_err(dev, "invalid clock rate\n");
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return -EINVAL;
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}
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/* check if there is pretimeout support */
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irq = platform_get_irq_optional(pdev, 0);
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if (data->pretimeout && irq > 0) {
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ret = devm_request_irq(dev, irq, qcom_wdt_isr, 0,
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"wdt_bark", &wdt->wdd);
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if (ret)
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return ret;
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wdt->wdd.info = &qcom_wdt_pt_info;
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wdt->wdd.pretimeout = 1;
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} else {
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if (irq == -EPROBE_DEFER)
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return -EPROBE_DEFER;
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wdt->wdd.info = &qcom_wdt_info;
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}
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wdt->wdd.ops = &qcom_wdt_ops;
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wdt->wdd.min_timeout = 1;
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wdt->wdd.max_timeout = 0x10000000U / wdt->rate;
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wdt->wdd.parent = dev;
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wdt->layout = data->offset;
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if (readl(wdt_addr(wdt, WDT_STS)) & 1)
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wdt->wdd.bootstatus = WDIOF_CARDRESET;
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/*
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* If 'timeout-sec' unspecified in devicetree, assume a 30 second
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* default, unless the max timeout is less than 30 seconds, then use
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* the max instead.
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*/
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wdt->wdd.timeout = min(wdt->wdd.max_timeout, 30U);
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watchdog_init_timeout(&wdt->wdd, 0, dev);
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/*
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* If WDT is already running, call WDT start which
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* will stop the WDT, set timeouts as bootloader
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* might use different ones and set running bit
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* to inform the WDT subsystem to ping the WDT
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*/
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if (qcom_wdt_is_running(&wdt->wdd)) {
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qcom_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_watchdog_register_device(dev, &wdt->wdd);
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if (ret)
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return ret;
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platform_set_drvdata(pdev, wdt);
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return 0;
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}
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static int __maybe_unused qcom_wdt_suspend(struct device *dev)
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{
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struct qcom_wdt *wdt = dev_get_drvdata(dev);
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if (watchdog_active(&wdt->wdd))
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qcom_wdt_stop(&wdt->wdd);
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return 0;
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}
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static int __maybe_unused qcom_wdt_resume(struct device *dev)
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{
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struct qcom_wdt *wdt = dev_get_drvdata(dev);
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if (watchdog_active(&wdt->wdd))
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qcom_wdt_start(&wdt->wdd);
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return 0;
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}
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static const struct dev_pm_ops qcom_wdt_pm_ops = {
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SET_LATE_SYSTEM_SLEEP_PM_OPS(qcom_wdt_suspend, qcom_wdt_resume)
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};
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static const struct of_device_id qcom_wdt_of_table[] = {
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{ .compatible = "qcom,kpss-timer", .data = &match_data_apcs_tmr },
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{ .compatible = "qcom,scss-timer", .data = &match_data_apcs_tmr },
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{ .compatible = "qcom,kpss-wdt", .data = &match_data_kpss },
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{ },
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};
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MODULE_DEVICE_TABLE(of, qcom_wdt_of_table);
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static struct platform_driver qcom_watchdog_driver = {
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.probe = qcom_wdt_probe,
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.driver = {
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.name = KBUILD_MODNAME,
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.of_match_table = qcom_wdt_of_table,
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.pm = &qcom_wdt_pm_ops,
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},
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};
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module_platform_driver(qcom_watchdog_driver);
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MODULE_DESCRIPTION("QCOM KPSS Watchdog Driver");
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MODULE_LICENSE("GPL v2");
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