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![Wolfram Sang](/assets/img/avatar_default.png)
Add support for watchdogs (RWDT and SWDT) found on RCar Gen3 based SoCs from Renesas. Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com> Signed-off-by: Guenter Roeck <linux@roeck-us.net> Signed-off-by: Wim Van Sebroeck <wim@iguana.be>
213 lines
5.2 KiB
C
213 lines
5.2 KiB
C
/*
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* Watchdog driver for Renesas WDT watchdog
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*
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* Copyright (C) 2015-16 Wolfram Sang, Sang Engineering <wsa@sang-engineering.com>
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* Copyright (C) 2015-16 Renesas Electronics Corporation
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*
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* This program is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License version 2 as published by
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* the Free Software Foundation.
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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/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 RWDT_DEFAULT_TIMEOUT 60U
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static const unsigned int clk_divs[] = { 1, 4, 16, 32, 64, 128, 1024 };
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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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struct clk *clk;
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unsigned int clks_per_sec;
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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 - wdev->timeout * priv->clks_per_sec, 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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clk_prepare_enable(priv->clk);
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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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clk_disable_unprepare(priv->clk);
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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_ROUND_CLOSEST(65536 - val, priv->clks_per_sec);
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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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.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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};
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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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unsigned long rate;
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unsigned int clks_per_sec;
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int ret, i;
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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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priv->clk = devm_clk_get(&pdev->dev, NULL);
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if (IS_ERR(priv->clk))
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return PTR_ERR(priv->clk);
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rate = clk_get_rate(priv->clk);
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if (!rate)
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return -ENOENT;
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for (i = ARRAY_SIZE(clk_divs) - 1; i >= 0; i--) {
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clks_per_sec = DIV_ROUND_UP(rate, clk_divs[i]);
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if (clks_per_sec) {
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priv->clks_per_sec = clks_per_sec;
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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 (!clks_per_sec) {
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dev_err(&pdev->dev, "Can't find suitable clock divider\n");
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return -ERANGE;
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}
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pm_runtime_enable(&pdev->dev);
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pm_runtime_get_sync(&pdev->dev);
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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 = 65536 / clks_per_sec;
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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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/* 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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pm_runtime_put(&pdev->dev);
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pm_runtime_disable(&pdev->dev);
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return ret;
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}
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return 0;
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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_put(&pdev->dev);
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pm_runtime_disable(&pdev->dev);
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return 0;
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}
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/*
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* This driver does also fit for R-Car Gen2 (r8a779[0-4]) WDT. However, for SMP
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* to work there, one also needs a RESET (RST) driver which does not exist yet
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* due to HW issues. This needs to be solved before adding compatibles here.
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*/
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static const struct of_device_id rwdt_ids[] = {
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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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},
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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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