diff options
Diffstat (limited to 'drivers/watchdog/renesas_wwdt.c')
| -rw-r--r-- | drivers/watchdog/renesas_wwdt.c | 163 |
1 files changed, 163 insertions, 0 deletions
diff --git a/drivers/watchdog/renesas_wwdt.c b/drivers/watchdog/renesas_wwdt.c new file mode 100644 index 000000000000..b250913c349a --- /dev/null +++ b/drivers/watchdog/renesas_wwdt.c @@ -0,0 +1,163 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Driver for the Renesas Window Watchdog Timer (WWDT) + * + * The WWDT can only be setup once after boot. Because we cannot know if this + * already happened in early boot stages, it is mandated that the firmware + * configures the watchdog. Linux then adapts according to the given setup. + * Note that this watchdog reports in the default configuration an overflow to + * the Error Control Module which then decides further actions. Or the WWDT is + * configured to generate an interrupt. + */ + +#include <linux/bitfield.h> +#include <linux/clk.h> +#include <linux/interrupt.h> +#include <linux/io.h> +#include <linux/kernel.h> +#include <linux/module.h> +#include <linux/of.h> +#include <linux/platform_device.h> +#include <linux/watchdog.h> + +#define WDTA0WDTE 0x00 +#define WDTA0RUN BIT(7) +#define WDTA0_KEY 0x2c + +#define WDTA0MD 0x0c +#define WDTA0OVF(x) FIELD_GET(GENMASK(6, 4), x) +#define WDTA0WIE BIT(3) +#define WDTA0ERM BIT(2) +#define WDTA0WS(x) FIELD_GET(GENMASK(1, 0), x) + +struct wwdt_priv { + void __iomem *base; + struct watchdog_device wdev; +}; + +static int wwdt_start(struct watchdog_device *wdev) +{ + struct wwdt_priv *priv = container_of(wdev, struct wwdt_priv, wdev); + + writeb(WDTA0RUN | WDTA0_KEY, priv->base + WDTA0WDTE); + return 0; +} + +static const struct watchdog_info wwdt_ident = { + .options = WDIOF_KEEPALIVEPING | WDIOF_ALARMONLY, + .identity = "Renesas Window Watchdog", +}; + +static const struct watchdog_ops wwdt_ops = { + .owner = THIS_MODULE, + .start = wwdt_start, +}; + +static irqreturn_t wwdt_error_irq(int irq, void *dev_id) +{ + struct device *dev = dev_id; + + dev_warn(dev, "Watchdog timed out\n"); + return IRQ_HANDLED; +} + +static irqreturn_t wwdt_pretimeout_irq(int irq, void *dev_id) +{ + struct watchdog_device *wdev = dev_id; + + watchdog_notify_pretimeout(wdev); + return IRQ_HANDLED; +} + +static int wwdt_probe(struct platform_device *pdev) +{ + struct device *dev = &pdev->dev; + struct wwdt_priv *priv; + struct watchdog_device *wdev; + struct clk *clk; + unsigned long rate; + unsigned int interval, window_size; + int ret; + u8 val; + + priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL); + if (!priv) + return -ENOMEM; + + priv->base = devm_platform_ioremap_resource(pdev, 0); + if (IS_ERR(priv->base)) + return PTR_ERR(priv->base); + + clk = devm_clk_get(dev, "cnt"); + if (IS_ERR(clk)) + return PTR_ERR(clk); + + rate = clk_get_rate(clk); + if (!rate) + return -EINVAL; + + wdev = &priv->wdev; + + val = readb(priv->base + WDTA0WDTE); + if (val & WDTA0RUN) + set_bit(WDOG_HW_RUNNING, &wdev->status); + + val = readb(priv->base + WDTA0MD); + interval = 1 << (9 + WDTA0OVF(val)); + /* size of the closed(!) window per mille */ + window_size = 250 * (3 - WDTA0WS(val)); + + wdev->info = &wwdt_ident; + wdev->ops = &wwdt_ops; + wdev->parent = dev; + wdev->min_hw_heartbeat_ms = window_size * interval / rate; + wdev->max_hw_heartbeat_ms = 1000 * interval / rate; + wdev->timeout = DIV_ROUND_UP(wdev->max_hw_heartbeat_ms, 1000); + watchdog_set_nowayout(wdev, true); + + if (!(val & WDTA0ERM)) { + ret = platform_get_irq_byname(pdev, "error"); + if (ret < 0) + return ret; + + ret = devm_request_threaded_irq(dev, ret, NULL, wwdt_error_irq, + IRQF_ONESHOT, NULL, dev); + if (ret < 0) + return ret; + } + + if (val & WDTA0WIE) { + ret = platform_get_irq_byname(pdev, "pretimeout"); + if (ret < 0) + return ret; + + ret = devm_request_threaded_irq(dev, ret, NULL, wwdt_pretimeout_irq, + IRQF_ONESHOT, NULL, wdev); + if (ret < 0) + return ret; + } + + devm_watchdog_register_device(dev, wdev); + + return 0; +} + +static const struct of_device_id renesas_wwdt_ids[] = { + { .compatible = "renesas,rcar-gen3-wwdt", }, + { .compatible = "renesas,rcar-gen4-wwdt", }, + { /* sentinel */ } +}; +MODULE_DEVICE_TABLE(of, renesas_wwdt_ids); + +static struct platform_driver renesas_wwdt_driver = { + .driver = { + .name = "renesas_wwdt", + .of_match_table = renesas_wwdt_ids, + }, + .probe = wwdt_probe, +}; +module_platform_driver(renesas_wwdt_driver); + +MODULE_DESCRIPTION("Renesas Window Watchdog (WWDT) Driver"); +MODULE_LICENSE("GPL"); +MODULE_AUTHOR("Wolfram Sang <wsa+renesas@sang-engineering.com>"); |