164 lines
4.0 KiB
C
164 lines
4.0 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/*
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* Driver for the Renesas Window Watchdog Timer (WWDT)
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*
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* The WWDT can only be setup once after boot. Because we cannot know if this
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* already happened in early boot stages, it is mandated that the firmware
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* configures the watchdog. Linux then adapts according to the given setup.
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* Note that this watchdog reports in the default configuration an overflow to
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* the Error Control Module which then decides further actions. Or the WWDT is
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* configured to generate an interrupt.
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*/
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#include <linux/bitfield.h>
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#include <linux/clk.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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#define WDTA0WDTE 0x00
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#define WDTA0RUN BIT(7)
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#define WDTA0_KEY 0x2c
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#define WDTA0MD 0x0c
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#define WDTA0OVF(x) FIELD_GET(GENMASK(6, 4), x)
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#define WDTA0WIE BIT(3)
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#define WDTA0ERM BIT(2)
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#define WDTA0WS(x) FIELD_GET(GENMASK(1, 0), x)
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struct wwdt_priv {
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void __iomem *base;
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struct watchdog_device wdev;
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};
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static int wwdt_start(struct watchdog_device *wdev)
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{
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struct wwdt_priv *priv = container_of(wdev, struct wwdt_priv, wdev);
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writeb(WDTA0RUN | WDTA0_KEY, priv->base + WDTA0WDTE);
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return 0;
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}
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static const struct watchdog_info wwdt_ident = {
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.options = WDIOF_KEEPALIVEPING | WDIOF_ALARMONLY,
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.identity = "Renesas Window Watchdog",
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};
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static const struct watchdog_ops wwdt_ops = {
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.owner = THIS_MODULE,
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.start = wwdt_start,
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};
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static irqreturn_t wwdt_error_irq(int irq, void *dev_id)
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{
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struct device *dev = dev_id;
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dev_warn(dev, "Watchdog timed out\n");
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return IRQ_HANDLED;
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}
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static irqreturn_t wwdt_pretimeout_irq(int irq, void *dev_id)
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{
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struct watchdog_device *wdev = dev_id;
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watchdog_notify_pretimeout(wdev);
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return IRQ_HANDLED;
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}
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static int wwdt_probe(struct platform_device *pdev)
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{
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struct device *dev = &pdev->dev;
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struct wwdt_priv *priv;
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struct watchdog_device *wdev;
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struct clk *clk;
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unsigned long rate;
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unsigned int interval, window_size;
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int ret;
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u8 val;
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priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
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if (!priv)
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return -ENOMEM;
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priv->base = devm_platform_ioremap_resource(pdev, 0);
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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(dev, "cnt");
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if (IS_ERR(clk))
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return PTR_ERR(clk);
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rate = clk_get_rate(clk);
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if (!rate)
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return -EINVAL;
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wdev = &priv->wdev;
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val = readb(priv->base + WDTA0WDTE);
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if (val & WDTA0RUN)
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set_bit(WDOG_HW_RUNNING, &wdev->status);
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val = readb(priv->base + WDTA0MD);
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interval = 1 << (9 + WDTA0OVF(val));
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/* size of the closed(!) window per mille */
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window_size = 250 * (3 - WDTA0WS(val));
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wdev->info = &wwdt_ident;
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wdev->ops = &wwdt_ops;
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wdev->parent = dev;
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wdev->min_hw_heartbeat_ms = window_size * interval / rate;
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wdev->max_hw_heartbeat_ms = 1000 * interval / rate;
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wdev->timeout = DIV_ROUND_UP(wdev->max_hw_heartbeat_ms, 1000);
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watchdog_set_nowayout(wdev, true);
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if (!(val & WDTA0ERM)) {
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ret = platform_get_irq_byname(pdev, "error");
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if (ret < 0)
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return ret;
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ret = devm_request_threaded_irq(dev, ret, NULL, wwdt_error_irq,
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IRQF_ONESHOT, NULL, dev);
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if (ret < 0)
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return ret;
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}
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if (val & WDTA0WIE) {
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ret = platform_get_irq_byname(pdev, "pretimeout");
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if (ret < 0)
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return ret;
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ret = devm_request_threaded_irq(dev, ret, NULL, wwdt_pretimeout_irq,
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IRQF_ONESHOT, NULL, wdev);
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if (ret < 0)
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return ret;
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}
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devm_watchdog_register_device(dev, wdev);
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return 0;
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}
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static const struct of_device_id renesas_wwdt_ids[] = {
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{ .compatible = "renesas,rcar-gen3-wwdt", },
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{ .compatible = "renesas,rcar-gen4-wwdt", },
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{ /* sentinel */ }
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};
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MODULE_DEVICE_TABLE(of, renesas_wwdt_ids);
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static struct platform_driver renesas_wwdt_driver = {
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.driver = {
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.name = "renesas_wwdt",
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.of_match_table = renesas_wwdt_ids,
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},
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.probe = wwdt_probe,
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};
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module_platform_driver(renesas_wwdt_driver);
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MODULE_DESCRIPTION("Renesas Window Watchdog (WWDT) Driver");
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MODULE_LICENSE("GPL");
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MODULE_AUTHOR("Wolfram Sang <wsa+renesas@sang-engineering.com>");
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