/* * Watchdog driver for Renesas WDT watchdog * * Copyright (C) 2015-16 Wolfram Sang, Sang Engineering <wsa@sang-engineering.com> * Copyright (C) 2015-16 Renesas Electronics Corporation * * This program is free software; you can redistribute it and/or modify it * under the terms of the GNU General Public License version 2 as published by * the Free Software Foundation. */ #include <linux/bitops.h> #include <linux/clk.h> #include <linux/io.h> #include <linux/kernel.h> #include <linux/module.h> #include <linux/of.h> #include <linux/platform_device.h> #include <linux/pm_runtime.h> #include <linux/watchdog.h> #define RWTCNT 0 #define RWTCSRA 4 #define RWTCSRA_WOVF BIT(4) #define RWTCSRA_WRFLG BIT(5) #define RWTCSRA_TME BIT(7) #define RWDT_DEFAULT_TIMEOUT 60U static const unsigned int clk_divs[] = { 1, 4, 16, 32, 64, 128, 1024 }; static bool nowayout = WATCHDOG_NOWAYOUT; module_param(nowayout, bool, 0); MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default=" __MODULE_STRING(WATCHDOG_NOWAYOUT) ")"); struct rwdt_priv { void __iomem *base; struct watchdog_device wdev; struct clk *clk; unsigned int clks_per_sec; u8 cks; }; static void rwdt_write(struct rwdt_priv *priv, u32 val, unsigned int reg) { if (reg == RWTCNT) val |= 0x5a5a0000; else val |= 0xa5a5a500; writel_relaxed(val, priv->base + reg); } static int rwdt_init_timeout(struct watchdog_device *wdev) { struct rwdt_priv *priv = watchdog_get_drvdata(wdev); rwdt_write(priv, 65536 - wdev->timeout * priv->clks_per_sec, RWTCNT); return 0; } static int rwdt_start(struct watchdog_device *wdev) { struct rwdt_priv *priv = watchdog_get_drvdata(wdev); clk_prepare_enable(priv->clk); rwdt_write(priv, priv->cks, RWTCSRA); rwdt_init_timeout(wdev); while (readb_relaxed(priv->base + RWTCSRA) & RWTCSRA_WRFLG) cpu_relax(); rwdt_write(priv, priv->cks | RWTCSRA_TME, RWTCSRA); return 0; } static int rwdt_stop(struct watchdog_device *wdev) { struct rwdt_priv *priv = watchdog_get_drvdata(wdev); rwdt_write(priv, priv->cks, RWTCSRA); clk_disable_unprepare(priv->clk); return 0; } static unsigned int rwdt_get_timeleft(struct watchdog_device *wdev) { struct rwdt_priv *priv = watchdog_get_drvdata(wdev); u16 val = readw_relaxed(priv->base + RWTCNT); return DIV_ROUND_CLOSEST(65536 - val, priv->clks_per_sec); } static const struct watchdog_info rwdt_ident = { .options = WDIOF_MAGICCLOSE | WDIOF_KEEPALIVEPING | WDIOF_SETTIMEOUT, .identity = "Renesas WDT Watchdog", }; static const struct watchdog_ops rwdt_ops = { .owner = THIS_MODULE, .start = rwdt_start, .stop = rwdt_stop, .ping = rwdt_init_timeout, .get_timeleft = rwdt_get_timeleft, }; static int rwdt_probe(struct platform_device *pdev) { struct rwdt_priv *priv; struct resource *res; unsigned long rate; unsigned int clks_per_sec; int ret, i; priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL); if (!priv) return -ENOMEM; res = platform_get_resource(pdev, IORESOURCE_MEM, 0); priv->base = devm_ioremap_resource(&pdev->dev, res); if (IS_ERR(priv->base)) return PTR_ERR(priv->base); priv->clk = devm_clk_get(&pdev->dev, NULL); if (IS_ERR(priv->clk)) return PTR_ERR(priv->clk); rate = clk_get_rate(priv->clk); if (!rate) return -ENOENT; for (i = ARRAY_SIZE(clk_divs) - 1; i >= 0; i--) { clks_per_sec = DIV_ROUND_UP(rate, clk_divs[i]); if (clks_per_sec) { priv->clks_per_sec = clks_per_sec; priv->cks = i; break; } } if (!clks_per_sec) { dev_err(&pdev->dev, "Can't find suitable clock divider\n"); return -ERANGE; } pm_runtime_enable(&pdev->dev); pm_runtime_get_sync(&pdev->dev); priv->wdev.info = &rwdt_ident, priv->wdev.ops = &rwdt_ops, priv->wdev.parent = &pdev->dev; priv->wdev.min_timeout = 1; priv->wdev.max_timeout = 65536 / clks_per_sec; priv->wdev.timeout = min(priv->wdev.max_timeout, RWDT_DEFAULT_TIMEOUT); platform_set_drvdata(pdev, priv); watchdog_set_drvdata(&priv->wdev, priv); watchdog_set_nowayout(&priv->wdev, nowayout); /* This overrides the default timeout only if DT configuration was found */ ret = watchdog_init_timeout(&priv->wdev, 0, &pdev->dev); if (ret) dev_warn(&pdev->dev, "Specified timeout value invalid, using default\n"); ret = watchdog_register_device(&priv->wdev); if (ret < 0) { pm_runtime_put(&pdev->dev); pm_runtime_disable(&pdev->dev); return ret; } return 0; } static int rwdt_remove(struct platform_device *pdev) { struct rwdt_priv *priv = platform_get_drvdata(pdev); watchdog_unregister_device(&priv->wdev); pm_runtime_put(&pdev->dev); pm_runtime_disable(&pdev->dev); return 0; } /* * This driver does also fit for R-Car Gen2 (r8a779[0-4]) WDT. However, for SMP * to work there, one also needs a RESET (RST) driver which does not exist yet * due to HW issues. This needs to be solved before adding compatibles here. */ static const struct of_device_id rwdt_ids[] = { { .compatible = "renesas,rcar-gen3-wdt", }, { /* sentinel */ } }; MODULE_DEVICE_TABLE(of, rwdt_ids); static struct platform_driver rwdt_driver = { .driver = { .name = "renesas_wdt", .of_match_table = rwdt_ids, }, .probe = rwdt_probe, .remove = rwdt_remove, }; module_platform_driver(rwdt_driver); MODULE_DESCRIPTION("Renesas WDT Watchdog Driver"); MODULE_LICENSE("GPL v2"); MODULE_AUTHOR("Wolfram Sang <wsa@sang-engineering.com>");