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![Wolfram Sang](/assets/img/avatar_default.png)
We want to go into a sane state when unregistering. Currently, it happens that the watchdog stops when unbinding because of RuntimePM stopping the core clock. When rebinding, the core clock gets reactivated and the watchdog fires even though it hasn't been opened by userspace yet. Strange scenario, yes, but sane state is much preferred anyhow. Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com> Reviewed-by: Fabrizio Castro <fabrizio.castro@bp.renesas.com> Reviewed-by: Guenter Roeck <linux@roeck-us.net> Signed-off-by: Guenter Roeck <linux@roeck-us.net> Signed-off-by: Wim Van Sebroeck <wim@linux-watchdog.org>
306 lines
7.5 KiB
C
306 lines
7.5 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/*
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* Watchdog driver for Renesas WDT watchdog
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*
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* Copyright (C) 2015-17 Wolfram Sang, Sang Engineering <wsa@sang-engineering.com>
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* Copyright (C) 2015-17 Renesas Electronics Corporation
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*/
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#include <linux/bitops.h>
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#include <linux/clk.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/pm_runtime.h>
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#include <linux/smp.h>
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#include <linux/sys_soc.h>
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#include <linux/watchdog.h>
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#define RWTCNT 0
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#define RWTCSRA 4
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#define RWTCSRA_WOVF BIT(4)
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#define RWTCSRA_WRFLG BIT(5)
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#define RWTCSRA_TME BIT(7)
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#define RWTCSRB 8
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#define RWDT_DEFAULT_TIMEOUT 60U
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/*
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* In probe, clk_rate is checked to be not more than 16 bit * biggest clock
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* divider (12 bits). d is only a factor to fully utilize the WDT counter and
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* will not exceed its 16 bits. Thus, no overflow, we stay below 32 bits.
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*/
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#define MUL_BY_CLKS_PER_SEC(p, d) \
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DIV_ROUND_UP((d) * (p)->clk_rate, clk_divs[(p)->cks])
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/* d is 16 bit, clk_divs 12 bit -> no 32 bit overflow */
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#define DIV_BY_CLKS_PER_SEC(p, d) ((d) * clk_divs[(p)->cks] / (p)->clk_rate)
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static const unsigned int clk_divs[] = { 1, 4, 16, 32, 64, 128, 1024, 4096 };
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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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struct rwdt_priv {
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void __iomem *base;
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struct watchdog_device wdev;
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unsigned long clk_rate;
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u16 time_left;
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u8 cks;
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};
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static void rwdt_write(struct rwdt_priv *priv, u32 val, unsigned int reg)
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{
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if (reg == RWTCNT)
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val |= 0x5a5a0000;
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else
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val |= 0xa5a5a500;
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writel_relaxed(val, priv->base + reg);
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}
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static int rwdt_init_timeout(struct watchdog_device *wdev)
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{
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struct rwdt_priv *priv = watchdog_get_drvdata(wdev);
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rwdt_write(priv, 65536 - MUL_BY_CLKS_PER_SEC(priv, wdev->timeout), RWTCNT);
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return 0;
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}
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static int rwdt_start(struct watchdog_device *wdev)
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{
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struct rwdt_priv *priv = watchdog_get_drvdata(wdev);
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pm_runtime_get_sync(wdev->parent);
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rwdt_write(priv, 0, RWTCSRB);
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rwdt_write(priv, priv->cks, RWTCSRA);
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rwdt_init_timeout(wdev);
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while (readb_relaxed(priv->base + RWTCSRA) & RWTCSRA_WRFLG)
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cpu_relax();
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rwdt_write(priv, priv->cks | RWTCSRA_TME, RWTCSRA);
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return 0;
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}
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static int rwdt_stop(struct watchdog_device *wdev)
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{
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struct rwdt_priv *priv = watchdog_get_drvdata(wdev);
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rwdt_write(priv, priv->cks, RWTCSRA);
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pm_runtime_put(wdev->parent);
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return 0;
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}
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static unsigned int rwdt_get_timeleft(struct watchdog_device *wdev)
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{
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struct rwdt_priv *priv = watchdog_get_drvdata(wdev);
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u16 val = readw_relaxed(priv->base + RWTCNT);
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return DIV_BY_CLKS_PER_SEC(priv, 65536 - val);
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}
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static int rwdt_restart(struct watchdog_device *wdev, unsigned long action,
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void *data)
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{
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struct rwdt_priv *priv = watchdog_get_drvdata(wdev);
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rwdt_start(wdev);
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rwdt_write(priv, 0xffff, RWTCNT);
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return 0;
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}
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static const struct watchdog_info rwdt_ident = {
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.options = WDIOF_MAGICCLOSE | WDIOF_KEEPALIVEPING | WDIOF_SETTIMEOUT |
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WDIOF_CARDRESET,
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.identity = "Renesas WDT Watchdog",
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};
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static const struct watchdog_ops rwdt_ops = {
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.owner = THIS_MODULE,
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.start = rwdt_start,
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.stop = rwdt_stop,
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.ping = rwdt_init_timeout,
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.get_timeleft = rwdt_get_timeleft,
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.restart = rwdt_restart,
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};
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#if defined(CONFIG_ARCH_RCAR_GEN2) && defined(CONFIG_SMP)
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/*
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* Watchdog-reset integration is broken on early revisions of R-Car Gen2 SoCs
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*/
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static const struct soc_device_attribute rwdt_quirks_match[] = {
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{
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.soc_id = "r8a7790",
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.revision = "ES1.*",
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.data = (void *)1, /* needs single CPU */
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}, {
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.soc_id = "r8a7791",
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.revision = "ES1.*",
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.data = (void *)1, /* needs single CPU */
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}, {
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.soc_id = "r8a7792",
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.revision = "*",
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.data = (void *)0, /* needs SMP disabled */
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},
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{ /* sentinel */ }
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};
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static bool rwdt_blacklisted(struct device *dev)
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{
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const struct soc_device_attribute *attr;
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attr = soc_device_match(rwdt_quirks_match);
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if (attr && setup_max_cpus > (uintptr_t)attr->data) {
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dev_info(dev, "Watchdog blacklisted on %s %s\n", attr->soc_id,
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attr->revision);
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return true;
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}
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return false;
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}
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#else /* !CONFIG_ARCH_RCAR_GEN2 || !CONFIG_SMP */
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static inline bool rwdt_blacklisted(struct device *dev) { return false; }
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#endif /* !CONFIG_ARCH_RCAR_GEN2 || !CONFIG_SMP */
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static int rwdt_probe(struct platform_device *pdev)
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{
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struct rwdt_priv *priv;
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struct resource *res;
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struct clk *clk;
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unsigned long clks_per_sec;
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int ret, i;
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if (rwdt_blacklisted(&pdev->dev))
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return -ENODEV;
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priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL);
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if (!priv)
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return -ENOMEM;
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res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
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priv->base = devm_ioremap_resource(&pdev->dev, res);
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if (IS_ERR(priv->base))
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return PTR_ERR(priv->base);
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clk = devm_clk_get(&pdev->dev, NULL);
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if (IS_ERR(clk))
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return PTR_ERR(clk);
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pm_runtime_enable(&pdev->dev);
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pm_runtime_get_sync(&pdev->dev);
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priv->clk_rate = clk_get_rate(clk);
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priv->wdev.bootstatus = (readb_relaxed(priv->base + RWTCSRA) &
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RWTCSRA_WOVF) ? WDIOF_CARDRESET : 0;
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pm_runtime_put(&pdev->dev);
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if (!priv->clk_rate) {
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ret = -ENOENT;
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goto out_pm_disable;
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}
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for (i = ARRAY_SIZE(clk_divs) - 1; i >= 0; i--) {
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clks_per_sec = priv->clk_rate / clk_divs[i];
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if (clks_per_sec && clks_per_sec < 65536) {
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priv->cks = i;
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break;
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}
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}
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if (i < 0) {
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dev_err(&pdev->dev, "Can't find suitable clock divider\n");
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ret = -ERANGE;
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goto out_pm_disable;
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}
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priv->wdev.info = &rwdt_ident,
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priv->wdev.ops = &rwdt_ops,
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priv->wdev.parent = &pdev->dev;
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priv->wdev.min_timeout = 1;
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priv->wdev.max_timeout = DIV_BY_CLKS_PER_SEC(priv, 65536);
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priv->wdev.timeout = min(priv->wdev.max_timeout, RWDT_DEFAULT_TIMEOUT);
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platform_set_drvdata(pdev, priv);
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watchdog_set_drvdata(&priv->wdev, priv);
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watchdog_set_nowayout(&priv->wdev, nowayout);
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watchdog_set_restart_priority(&priv->wdev, 0);
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watchdog_stop_on_unregister(&priv->wdev);
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/* This overrides the default timeout only if DT configuration was found */
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ret = watchdog_init_timeout(&priv->wdev, 0, &pdev->dev);
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if (ret)
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dev_warn(&pdev->dev, "Specified timeout value invalid, using default\n");
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ret = watchdog_register_device(&priv->wdev);
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if (ret < 0)
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goto out_pm_disable;
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return 0;
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out_pm_disable:
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pm_runtime_disable(&pdev->dev);
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return ret;
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}
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static int rwdt_remove(struct platform_device *pdev)
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{
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struct rwdt_priv *priv = platform_get_drvdata(pdev);
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watchdog_unregister_device(&priv->wdev);
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pm_runtime_disable(&pdev->dev);
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return 0;
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}
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static int __maybe_unused rwdt_suspend(struct device *dev)
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{
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struct rwdt_priv *priv = dev_get_drvdata(dev);
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if (watchdog_active(&priv->wdev)) {
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priv->time_left = readw(priv->base + RWTCNT);
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rwdt_stop(&priv->wdev);
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}
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return 0;
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}
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static int __maybe_unused rwdt_resume(struct device *dev)
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{
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struct rwdt_priv *priv = dev_get_drvdata(dev);
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if (watchdog_active(&priv->wdev)) {
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rwdt_start(&priv->wdev);
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rwdt_write(priv, priv->time_left, RWTCNT);
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}
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return 0;
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}
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static SIMPLE_DEV_PM_OPS(rwdt_pm_ops, rwdt_suspend, rwdt_resume);
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static const struct of_device_id rwdt_ids[] = {
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{ .compatible = "renesas,rcar-gen2-wdt", },
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{ .compatible = "renesas,rcar-gen3-wdt", },
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{ /* sentinel */ }
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};
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MODULE_DEVICE_TABLE(of, rwdt_ids);
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static struct platform_driver rwdt_driver = {
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.driver = {
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.name = "renesas_wdt",
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.of_match_table = rwdt_ids,
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.pm = &rwdt_pm_ops,
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},
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.probe = rwdt_probe,
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.remove = rwdt_remove,
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};
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module_platform_driver(rwdt_driver);
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MODULE_DESCRIPTION("Renesas WDT Watchdog Driver");
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MODULE_LICENSE("GPL v2");
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MODULE_AUTHOR("Wolfram Sang <wsa@sang-engineering.com>");
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