[PATCH v2 2/2] watchdog: Add Aspeed watchdog driver
Guenter Roeck
linux at roeck-us.net
Sat May 14 14:34:50 PDT 2016
On 05/12/2016 07:17 AM, Joel Stanley wrote:
> Provides generic watchdog features as well as reboot support for the
> Apeed SoC.
>
> Signed-off-by: Joel Stanley <joel at jms.id.au>
> ---
> drivers/watchdog/Kconfig | 13 +++
> drivers/watchdog/Makefile | 1 +
> drivers/watchdog/aspeed_wdt.c | 209 ++++++++++++++++++++++++++++++++++++++++++
> 3 files changed, 223 insertions(+)
> create mode 100644 drivers/watchdog/aspeed_wdt.c
>
> diff --git a/drivers/watchdog/Kconfig b/drivers/watchdog/Kconfig
> index fb947655badd..4f0e2ded4785 100644
> --- a/drivers/watchdog/Kconfig
> +++ b/drivers/watchdog/Kconfig
> @@ -661,6 +661,19 @@ config ATLAS7_WATCHDOG
> To compile this driver as a module, choose M here: the
> module will be called atlas7_wdt.
>
> +config ASPEED_WATCHDOG
> + tristate "Aspeed watchdog support"
> + depends on ARCH_ASPEED || COMPILE_TEST
> + select WATCHDOG_CORE
> + help
> + Say Y here to include support for the watchdog timer
> + in Apseed BMC SoCs.
> +
> + This driver is required to reboot the SoC.
> +
> + To compile this driver as a module, choose M here: the
> + module will be called aspeed_wdt.
> +
> # AVR32 Architecture
>
> config AT32AP700X_WDT
> diff --git a/drivers/watchdog/Makefile b/drivers/watchdog/Makefile
> index feb6270fdbde..36855375e0ce 100644
> --- a/drivers/watchdog/Makefile
> +++ b/drivers/watchdog/Makefile
> @@ -73,6 +73,7 @@ obj-$(CONFIG_DIGICOLOR_WATCHDOG) += digicolor_wdt.o
> obj-$(CONFIG_LPC18XX_WATCHDOG) += lpc18xx_wdt.o
> obj-$(CONFIG_BCM7038_WDT) += bcm7038_wdt.o
> obj-$(CONFIG_ATLAS7_WATCHDOG) += atlas7_wdt.o
> +obj-$(CONFIG_ASPEED_WATCHDOG) += aspeed_wdt.o
>
> # AVR32 Architecture
> obj-$(CONFIG_AT32AP700X_WDT) += at32ap700x_wdt.o
> diff --git a/drivers/watchdog/aspeed_wdt.c b/drivers/watchdog/aspeed_wdt.c
> new file mode 100644
> index 000000000000..f7ae41ef4121
> --- /dev/null
> +++ b/drivers/watchdog/aspeed_wdt.c
> @@ -0,0 +1,209 @@
> +/*
> + * Copyright 2016 IBM Corporation
> + *
> + * Joel Stanley <joel at jms.id.au>
> + *
> + * Based on the qcom-watchdog driver
> + *
> + * This program is free software; you can redistribute it and/or
> + * modify it under the terms of the GNU General Public License
> + * as published by the Free Software Foundation; either version
> + * 2 of the License, or (at your option) any later version.
> + */
> +#include <linux/kernel.h>
> +#include <linux/module.h>
> +#include <linux/of.h>
> +#include <linux/watchdog.h>
> +#include <linux/platform_device.h>
> +#include <linux/io.h>
> +
> +struct aspeed_wdt {
> + struct watchdog_device wdd;
> + unsigned long rate;
I still don't see why you need this variable. Why not just use
WDT_1MHZ_CLOCK directly ?
> + void __iomem *base;
> + u32 ctrl;
> +};
> +
> +static const struct of_device_id aspeed_wdt_of_table[] = {
> + { .compatible = "aspeed,ast2400-wdt" },
> + { .compatible = "aspeed,ast2500-wdt" },
> + { },
> +};
> +MODULE_DEVICE_TABLE(of, aspeed_wdt_of_table);
> +
> +#define WDT_STATUS 0x00
> +#define WDT_RELOAD_VALUE 0x04
> +#define WDT_RESTART 0x08
> +#define WDT_CTRL 0x0C
> +#define WDT_CTRL_RESET_MODE_SOC (0x00 << 5)
> +#define WDT_CTRL_RESET_MODE_FULL_CHIP (0x01 << 5)
> +#define WDT_CTRL_1MHZ_CLK BIT(4)
> +#define WDT_CTRL_WDT_EXT BIT(3)
> +#define WDT_CTRL_WDT_INTR BIT(2)
> +#define WDT_CTRL_RESET_SYSTEM BIT(1)
> +#define WDT_CTRL_ENABLE BIT(0)
> +
> +#define WDT_RESTART_MAGIC 0x4755
> +
> +#define WDT_MIN_TIMEOUT 1
> +/* 32 bits at 1MHz, in milliseconds */
> +#define WDT_MAX_TIMEOUT_MS 4294967
> +#define WDT_DEFAULT_TIMEOUT 30
> +#define WDT_1MHZ_CLOCK 1000000
> +
> +static struct aspeed_wdt *to_aspeed_wdt(struct watchdog_device *wdd)
> +{
> + return container_of(wdd, struct aspeed_wdt, wdd);
> +}
> +
> +static void aspeed_wdt_enable(struct aspeed_wdt *wdt, int count)
> +{
> + wdt->ctrl |= WDT_CTRL_ENABLE;
> +
> + writel(0, wdt->base + WDT_CTRL);
> + writel(count, wdt->base + WDT_RELOAD_VALUE);
> + writel(WDT_RESTART_MAGIC, wdt->base + WDT_RESTART);
> + writel(wdt->ctrl, wdt->base + WDT_CTRL);
> +}
> +
> +static int aspeed_wdt_start(struct watchdog_device *wdd)
> +{
> + struct aspeed_wdt *wdt = to_aspeed_wdt(wdd);
> +
> + aspeed_wdt_enable(wdt, wdd->timeout * wdt->rate);
> +
> + return 0;
> +}
> +
> +static int aspeed_wdt_stop(struct watchdog_device *wdd)
> +{
> + struct aspeed_wdt *wdt = to_aspeed_wdt(wdd);
> +
> + wdt->ctrl &= ~WDT_CTRL_ENABLE;
> + writel(wdt->ctrl, wdt->base + WDT_CTRL);
> +
> + return 0;
> +}
> +
> +static int aspeed_wdt_ping(struct watchdog_device *wdd)
> +{
> + struct aspeed_wdt *wdt = to_aspeed_wdt(wdd);
> +
> + writel(WDT_RESTART_MAGIC, wdt->base + WDT_RESTART);
> +
> + return 0;
> +}
> +
> +static int aspeed_wdt_set_timeout(struct watchdog_device *wdd,
> + unsigned int timeout)
> +{
> + wdd->timeout = timeout;
> +
> + return aspeed_wdt_start(wdd);
The watchdog can be stopped here (with WDIOC_SETOPTIONS/WDIOS_DISABLECARD).
An implicit enable is not really a good idea; neither the infrastructure
nor user space would in this case be aware that the watchdog is running.
> +}
> +
> +static int aspeed_wdt_restart(struct watchdog_device *wdd,
> + unsigned long action, void *data)
> +{
> + struct aspeed_wdt *wdt = to_aspeed_wdt(wdd);
> +
> + aspeed_wdt_enable(wdt, 128 * wdt->rate / 1000);
> +
Is that the smallest accepted value, or is there some other reason
not to make it smaller ?
It is also quite common to wait here to let the reset 'catch'
before returning. This would ensure that the system doesn't trigger
a lower priority reset.
> + return 0;
> +}
> +
> +static const struct watchdog_ops aspeed_wdt_ops = {
> + .start = aspeed_wdt_start,
> + .stop = aspeed_wdt_stop,
> + .ping = aspeed_wdt_ping,
> + .set_timeout = aspeed_wdt_set_timeout,
> + .restart = aspeed_wdt_restart,
> + .owner = THIS_MODULE,
> +};
> +
> +static const struct watchdog_info aspeed_wdt_info = {
> + .options = WDIOF_KEEPALIVEPING
> + | WDIOF_MAGICCLOSE
> + | WDIOF_SETTIMEOUT,
> + .identity = KBUILD_MODNAME,
> +};
> +
> +static int aspeed_wdt_remove(struct platform_device *pdev)
> +{
> + struct aspeed_wdt *wdt = platform_get_drvdata(pdev);
> +
> + watchdog_unregister_device(&wdt->wdd);
> +
> + return 0;
> +}
> +
> +static int aspeed_wdt_probe(struct platform_device *pdev)
> +{
> + struct aspeed_wdt *wdt;
> + struct resource *res;
> + int ret;
> +
> + wdt = devm_kzalloc(&pdev->dev, sizeof(*wdt), GFP_KERNEL);
> + if (!wdt)
> + return -ENOMEM;
> +
> + res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> + wdt->base = devm_ioremap_resource(&pdev->dev, res);
> + if (IS_ERR(wdt->base))
> + return PTR_ERR(wdt->base);
> +
> + /*
> + * The ast2400 wdt can run at PCLK, or 1MHz. The ast2500 only
> + * runs at 1MHz. We chose to always run at 1MHz, as there's no
> + * good reason to have a faster watchdog counter.
> + */
> + wdt->rate = WDT_1MHZ_CLOCK;
> + wdt->wdd.info = &aspeed_wdt_info;
> + wdt->wdd.ops = &aspeed_wdt_ops;
> + wdt->wdd.min_timeout = WDT_MIN_TIMEOUT;
> + wdt->wdd.max_hw_heartbeat_ms = WDT_MAX_TIMEOUT_MS;
> + wdt->wdd.parent = &pdev->dev;
> +
> + wdt->wdd.timeout = WDT_DEFAULT_TIMEOUT;
> + watchdog_init_timeout(&wdt->wdd, 0, &pdev->dev);
> +
> + /*
> + * Control reset on a per-device basis to ensure the
> + * host is not affected by a BMC reboot, so only reset
> + * the SOC and not the full chip
> + */
> + wdt->ctrl = WDT_CTRL_RESET_MODE_SOC |
> + WDT_CTRL_1MHZ_CLK |
> + WDT_CTRL_RESET_SYSTEM;
> +
> + if (readl(wdt->base + WDT_CTRL) & WDT_CTRL_ENABLE) {
> + aspeed_wdt_start(&wdt->wdd);
> + set_bit(WDOG_HW_RUNNING, &wdt->wdd.status);
> + }
> +
> + ret = watchdog_register_device(&wdt->wdd);
> + if (ret) {
> + dev_err(&pdev->dev, "failed to register\n");
> + return ret;
> + }
> +
> + dev_info(&pdev->dev, "rate %lu, max timeout %u, timeout %d\n",
> + wdt->rate, wdt->wdd.max_timeout, wdt->wdd.timeout);
> +
'rate 1000000' doesn't seem very informative. All it does is to expose
an implementation detail which no one really cares about. Even if you
were to add 'Hz', I would argue that no one will even understand
what it means without looking into the driver, but then it will be
understood without the message.
> + platform_set_drvdata(pdev, wdt);
> +
> + return 0;
> +}
> +
> +static struct platform_driver aspeed_watchdog_driver = {
> + .probe = aspeed_wdt_probe,
> + .remove = aspeed_wdt_remove,
> + .driver = {
> + .name = KBUILD_MODNAME,
> + .of_match_table = of_match_ptr(aspeed_wdt_of_table),
> + },
> +};
> +module_platform_driver(aspeed_watchdog_driver);
> +
> +MODULE_DESCRIPTION("Aspeed Watchdog Driver");
> +MODULE_LICENSE("GPL");
>
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