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Message-ID: <CANLsYkzQpEHa4hnO4D1E0+P-i961+ak=Hr_RPPrOxd-+VMhLSQ@mail.gmail.com>
Date: Thu, 4 Feb 2016 09:25:51 -0700
From: Mathieu Poirier <mathieu.poirier@...aro.org>
To: fu.wei@...aro.org
Cc: Rob Herring <robh+dt@...nel.org>,
Paweł Moll <pawel.moll@....com>,
Mark Rutland <mark.rutland@....com>,
Ian Campbell <ijc+devicetree@...lion.org.uk>,
Kumar Gala <galak@...eaurora.org>, wim@...ana.be,
linux@...ck-us.net, Jon Corbet <corbet@....net>,
Catalin Marinas <catalin.marinas@....com>,
Will Deacon <will.deacon@....com>,
Suravee.Suthikulpanit@....com,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
linux-watchdog@...r.kernel.org, linux-doc@...r.kernel.org,
"devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
"linux-arm-kernel@...ts.infradead.org"
<linux-arm-kernel@...ts.infradead.org>,
linaro-acpi@...ts.linaro.org, rruigrok@...eaurora.org,
harba@...eaurora.org, Christopher Covington <cov@...eaurora.org>,
timur@...eaurora.org, dyoung@...hat.com, panand@...hat.com,
graeme.gregory@...aro.org, al.stone@...aro.org,
hanjun.guo@...aro.org, jcm@...hat.com,
Arnd Bergmann <arnd@...db.de>, leo.duran@....com,
Sudeep Holla <sudeep.holla@....com>
Subject: Re: [PATCH v10 4/5] Watchdog: introduce ARM SBSA watchdog driver
On 3 February 2016 at 10:18, <fu.wei@...aro.org> wrote:
> From: Fu Wei <fu.wei@...aro.org>
>
> According to Server Base System Architecture (SBSA) specification,
> the SBSA Generic Watchdog has two stage timeouts: the first signal (WS0)
> is for alerting the system by interrupt, the second one (WS1) is a real
> hardware reset.
>
> This patch initially implements a simple single stage watchdog driver:
> when the timeout is reached, your system will be reset by the second
> signal (WS1).
> The first signal (WS0) is ignored in this driver.
>
> This driver bases on linux kernel watchdog framework, so it can get
> timeout from module parameter and FDT at the driver init stage.
>
> Signed-off-by: Fu Wei <fu.wei@...aro.org>
> Reviewed-by: Graeme Gregory <graeme.gregory@...aro.org>
> Tested-by: Pratyush Anand <panand@...hat.com>
> ---
> drivers/watchdog/Kconfig | 17 +++
> drivers/watchdog/Makefile | 1 +
> drivers/watchdog/sbsa_gwdt.c | 322 +++++++++++++++++++++++++++++++++++++++++++
> 3 files changed, 340 insertions(+)
>
> diff --git a/drivers/watchdog/Kconfig b/drivers/watchdog/Kconfig
> index 4f0e7be..4ab1b05 100644
> --- a/drivers/watchdog/Kconfig
> +++ b/drivers/watchdog/Kconfig
> @@ -201,6 +201,23 @@ config ARM_SP805_WATCHDOG
> ARM Primecell SP805 Watchdog timer. This will reboot your system when
> the timeout is reached.
>
> +config ARM_SBSA_WATCHDOG
> + tristate "ARM SBSA Generic Watchdog"
> + depends on ARM64
> + depends on ARM_ARCH_TIMER
> + select WATCHDOG_CORE
> + help
> + ARM SBSA Generic Watchdog has two stage timeouts:
> + the first signal (WS0) is for alerting the system by interrupt,
> + the second one (WS1) is a real hardware reset.
> + More details: ARM DEN0029B - Server Base System Architecture (SBSA)
> +
> + This is a simple single stage driver: when the timeout is reached,
> + your system will be reset by WS1. The first signal (WS0) is ignored.
> +
> + To compile this driver as module, choose M here: The module
> + will be called sbsa_gwdt.
> +
> config ASM9260_WATCHDOG
> tristate "Alphascale ASM9260 watchdog"
> depends on MACH_ASM9260
> diff --git a/drivers/watchdog/Makefile b/drivers/watchdog/Makefile
> index f566753..f9826d4 100644
> --- a/drivers/watchdog/Makefile
> +++ b/drivers/watchdog/Makefile
> @@ -30,6 +30,7 @@ obj-$(CONFIG_USBPCWATCHDOG) += pcwd_usb.o
>
> # ARM Architecture
> obj-$(CONFIG_ARM_SP805_WATCHDOG) += sp805_wdt.o
> +obj-$(CONFIG_ARM_SBSA_WATCHDOG) += sbsa_gwdt.o
> obj-$(CONFIG_ASM9260_WATCHDOG) += asm9260_wdt.o
> obj-$(CONFIG_AT91RM9200_WATCHDOG) += at91rm9200_wdt.o
> obj-$(CONFIG_AT91SAM9X_WATCHDOG) += at91sam9_wdt.o
> diff --git a/drivers/watchdog/sbsa_gwdt.c b/drivers/watchdog/sbsa_gwdt.c
> new file mode 100644
> index 0000000..5a2dba3
> --- /dev/null
> +++ b/drivers/watchdog/sbsa_gwdt.c
> @@ -0,0 +1,322 @@
> +/*
> + * SBSA(Server Base System Architecture) Generic Watchdog driver
> + *
> + * Copyright (c) 2015, Linaro Ltd.
> + * Author: Fu Wei <fu.wei@...aro.org>
> + * Suravee Suthikulpanit <Suravee.Suthikulpanit@....com>
> + * Al Stone <al.stone@...aro.org>
> + * Timur Tabi <timur@...eaurora.org>
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License 2 as published
> + * by the Free Software Foundation.
> + *
> + * This program is distributed in the hope that it will be useful,
> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
> + * GNU General Public License for more details.
> + *
> + * This SBSA Generic watchdog driver is a single stage timeout version.
> + * Since this watchdog timer has two stages, and each stage is determined
> + * by WOR. So the timeout is (WOR * 2).
> + * When first timeout is reached, WS0 is triggered, the interrupt
> + * triggered by WS0 will be ignored, then the second watch period starts;
> + * when second timeout is reached, then WS1 is triggered, system reset.
> + *
> + * More details about the hardware specification of this device:
> + * ARM DEN0029B - Server Base System Architecture (SBSA)
> + *
> + * SBSA GWDT: |--------WOR-------WS0--------WOR-------WS1
> + * |----------------timeout----------------reset
> + *
> + */
> +
> +#include <linux/io.h>
> +#include <linux/interrupt.h>
> +#include <linux/module.h>
> +#include <linux/moduleparam.h>
> +#include <linux/of.h>
> +#include <linux/of_device.h>
> +#include <linux/platform_device.h>
> +#include <linux/uaccess.h>
> +#include <linux/watchdog.h>
> +#include <asm/arch_timer.h>
> +
> +/* SBSA Generic Watchdog register definitions */
> +/* refresh frame */
> +#define SBSA_GWDT_WRR 0x000
> +
> +/* control frame */
> +#define SBSA_GWDT_WCS 0x000
> +#define SBSA_GWDT_WOR 0x008
> +#define SBSA_GWDT_WCV 0x010
> +
> +/* refresh/control frame */
> +#define SBSA_GWDT_W_IIDR 0xfcc
> +#define SBSA_GWDT_IDR 0xfd0
> +
> +/* Watchdog Control and Status Register */
> +#define SBSA_GWDT_WCS_EN BIT(0)
> +#define SBSA_GWDT_WCS_WS0 BIT(1)
> +#define SBSA_GWDT_WCS_WS1 BIT(2)
> +
> +/**
> + * struct sbsa_gwdt - Internal representation of the SBSA GWDT
> + * @wdd: kernel watchdog_device structure
> + * @clk: store the System Counter clock frequency, in Hz.
> + * @refresh_base: Virtual address of the watchdog refresh frame
> + * @control_base: Virtual address of the watchdog control frame
> + */
> +struct sbsa_gwdt {
> + struct watchdog_device wdd;
> + u32 clk;
> + void __iomem *refresh_base;
> + void __iomem *control_base;
> +};
> +
> +#define to_sbsa_gwdt(e) container_of(e, struct sbsa_gwdt, wdd)
> +
> +#define DEFAULT_TIMEOUT 20 /* seconds, the 1st + 2nd watch periods*/
> +
> +static unsigned int timeout;
> +module_param(timeout, uint, 0);
> +MODULE_PARM_DESC(timeout,
> + "Watchdog timeout in seconds. (>=0, default="
> + __MODULE_STRING(DEFAULT_TIMEOUT) ")");
> +
> +static bool nowayout = WATCHDOG_NOWAYOUT;
> +module_param(nowayout, bool, S_IRUGO);
> +MODULE_PARM_DESC(nowayout,
> + "Watchdog cannot be stopped once started (default="
> + __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
> +
> +/*
> + * watchdog operation functions
> + */
> +static int sbsa_gwdt_set_timeout(struct watchdog_device *wdd,
> + unsigned int timeout)
> +{
> + struct sbsa_gwdt *gwdt = to_sbsa_gwdt(wdd);
> +
> + wdd->timeout = timeout;
> + writel(timeout / 2 * gwdt->clk, gwdt->control_base + SBSA_GWDT_WOR);
> +
> + return 0;
> +}
> +
> +static unsigned int sbsa_gwdt_get_timeleft(struct watchdog_device *wdd)
> +{
> + struct sbsa_gwdt *gwdt = to_sbsa_gwdt(wdd);
> + u64 timeleft = readq(gwdt->control_base + SBSA_GWDT_WCV) -
> + arch_counter_get_cntvct();
> +
> + do_div(timeleft, gwdt->clk);
> +
> + if (readl(gwdt->control_base + SBSA_GWDT_WCS) & SBSA_GWDT_WCS_WS0)
> + return timeleft;
> +
> + return timeleft + wdd->timeout / 2;
It would be great to have a comment whenever hard coded values are
used. That way people understand why things were set this way. The
same applies for the rest of this patch.
> +}
> +
> +static int sbsa_gwdt_keepalive(struct watchdog_device *wdd)
> +{
> + struct sbsa_gwdt *gwdt = to_sbsa_gwdt(wdd);
> +
> + /*
> + * Writing WRR for an explicit watchdog refresh.
> + * You can write anyting(like 0xc0ffee).
> + */
> + writel(0xc0ffee, gwdt->refresh_base + SBSA_GWDT_WRR);
> +
> + return 0;
> +}
> +
> +static unsigned int sbsa_gwdt_status(struct watchdog_device *wdd)
> +{
> + struct sbsa_gwdt *gwdt = to_sbsa_gwdt(wdd);
> + u32 status = readl(gwdt->control_base + SBSA_GWDT_WCS);
> +
> + /* is the watchdog timer running? */
> + return (status & SBSA_GWDT_WCS_EN) << WDOG_ACTIVE;
> +}
> +
> +static int sbsa_gwdt_start(struct watchdog_device *wdd)
> +{
> + struct sbsa_gwdt *gwdt = to_sbsa_gwdt(wdd);
> +
> + /* writing WCS will cause an explicit watchdog refresh */
> + writel(SBSA_GWDT_WCS_EN, gwdt->control_base + SBSA_GWDT_WCS);
> +
> + return sbsa_gwdt_keepalive(wdd);
> +}
> +
> +static int sbsa_gwdt_stop(struct watchdog_device *wdd)
> +{
> + struct sbsa_gwdt *gwdt = to_sbsa_gwdt(wdd);
> +
> + writel(0, gwdt->control_base + SBSA_GWDT_WCS);
> +
> + return 0;
> +}
> +
> +static struct watchdog_info sbsa_gwdt_info = {
> + .identity = "SBSA Generic Watchdog",
> + .options = WDIOF_SETTIMEOUT |
> + WDIOF_KEEPALIVEPING |
> + WDIOF_MAGICCLOSE |
> + WDIOF_CARDRESET,
> +};
> +
> +static struct watchdog_ops sbsa_gwdt_ops = {
> + .owner = THIS_MODULE,
> + .start = sbsa_gwdt_start,
> + .stop = sbsa_gwdt_stop,
> + .status = sbsa_gwdt_status,
> + .ping = sbsa_gwdt_keepalive,
> + .set_timeout = sbsa_gwdt_set_timeout,
> + .get_timeleft = sbsa_gwdt_get_timeleft,
> +};
> +
> +static int sbsa_gwdt_probe(struct platform_device *pdev)
> +{
> + void __iomem *rf_base, *cf_base;
> + struct device *dev = &pdev->dev;
> + struct watchdog_device *wdd;
> + struct sbsa_gwdt *gwdt;
> + struct resource *res;
> + u32 status;
> + int ret;
> +
> + gwdt = devm_kzalloc(dev, sizeof(*gwdt), GFP_KERNEL);
> + if (!gwdt)
> + return -ENOMEM;
> + platform_set_drvdata(pdev, gwdt);
> +
> + res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> + cf_base = devm_ioremap_resource(dev, res);
> + if (IS_ERR(cf_base))
> + return PTR_ERR(cf_base);
> +
> + res = platform_get_resource(pdev, IORESOURCE_MEM, 1);
> + rf_base = devm_ioremap_resource(dev, res);
> + if (IS_ERR(rf_base))
> + return PTR_ERR(rf_base);
> +
> + /*
> + * Get the frequency of system counter from the cp15 interface of ARM
> + * Generic timer. We don't need to check it, because if it returns "0",
> + * system would panic in very early stage.
> + */
> + gwdt->clk = arch_timer_get_cntfrq();
> + gwdt->refresh_base = rf_base;
> + gwdt->control_base = cf_base;
> +
> + wdd = &gwdt->wdd;
> + wdd->parent = dev;
> + wdd->info = &sbsa_gwdt_info;
> + wdd->ops = &sbsa_gwdt_ops;
> + watchdog_set_drvdata(wdd, gwdt);
> + watchdog_set_nowayout(wdd, nowayout);
> +
> + wdd->min_timeout = 2;
> + wdd->max_timeout = U32_MAX / gwdt->clk * 2;
> + wdd->timeout = DEFAULT_TIMEOUT;
> + watchdog_init_timeout(wdd, timeout, dev);
> +
> + status = readl(gwdt->control_base + SBSA_GWDT_WCS);
> + if (status & SBSA_GWDT_WCS_WS1) {
> + dev_warn(dev, "System reset by WDT.\n");
> + wdd->bootstatus |= WDIOF_CARDRESET;
> + }
> +
> + ret = watchdog_register_device(wdd);
> + if (ret)
> + return ret;
> +
> + /*
> + * Update timeout to WOR.
> + * Because of the explicit watchdog refresh mechanism,
> + * it's also a ping, if watchdog is enabled.
> + */
> + sbsa_gwdt_set_timeout(wdd, wdd->timeout);
> +
> + dev_info(dev, "Initialized with %ds timeout @ %u Hz%s\n", wdd->timeout,
> + gwdt->clk, status & SBSA_GWDT_WCS_EN ? " [enabled]" : "");
> +
> + return 0;
> +}
> +
> +static void sbsa_gwdt_shutdown(struct platform_device *pdev)
> +{
> + struct sbsa_gwdt *gwdt = platform_get_drvdata(pdev);
> +
> + sbsa_gwdt_stop(&gwdt->wdd);
> +}
> +
> +static int sbsa_gwdt_remove(struct platform_device *pdev)
> +{
> + struct sbsa_gwdt *gwdt = platform_get_drvdata(pdev);
> +
> + watchdog_unregister_device(&gwdt->wdd);
> +
> + return 0;
> +}
> +
> +/* Disable watchdog if it is active during suspend */
> +static int __maybe_unused sbsa_gwdt_suspend(struct device *dev)
> +{
> + struct sbsa_gwdt *gwdt = dev_get_drvdata(dev);
> +
> + if (watchdog_active(&gwdt->wdd))
> + sbsa_gwdt_stop(&gwdt->wdd);
> +
> + return 0;
> +}
> +
> +/* Enable watchdog and configure it if necessary */
> +static int __maybe_unused sbsa_gwdt_resume(struct device *dev)
> +{
> + struct sbsa_gwdt *gwdt = dev_get_drvdata(dev);
> +
> + if (watchdog_active(&gwdt->wdd))
> + sbsa_gwdt_start(&gwdt->wdd);
> +
> + return 0;
> +}
> +
> +static const struct dev_pm_ops sbsa_gwdt_pm_ops = {
> + SET_SYSTEM_SLEEP_PM_OPS(sbsa_gwdt_suspend, sbsa_gwdt_resume)
> +};
> +
> +static const struct of_device_id sbsa_gwdt_of_match[] = {
> + { .compatible = "arm,sbsa-gwdt", },
> + {},
> +};
> +MODULE_DEVICE_TABLE(of, sbsa_gwdt_of_match);
> +
> +static const struct platform_device_id sbsa_gwdt_pdev_match[] = {
> + { .name = "sbsa-gwdt", },
> + {},
> +};
> +MODULE_DEVICE_TABLE(platform, sbsa_gwdt_pdev_match);
> +
> +static struct platform_driver sbsa_gwdt_driver = {
> + .driver = {
> + .name = "sbsa-gwdt",
> + .pm = &sbsa_gwdt_pm_ops,
> + .of_match_table = sbsa_gwdt_of_match,
> + },
> + .probe = sbsa_gwdt_probe,
> + .remove = sbsa_gwdt_remove,
> + .shutdown = sbsa_gwdt_shutdown,
> + .id_table = sbsa_gwdt_pdev_match,
> +};
> +
> +module_platform_driver(sbsa_gwdt_driver);
> +
> +MODULE_DESCRIPTION("SBSA Generic Watchdog Driver");
> +MODULE_AUTHOR("Fu Wei <fu.wei@...aro.org>");
> +MODULE_AUTHOR("Suravee Suthikulpanit <Suravee.Suthikulpanit@....com>");
> +MODULE_AUTHOR("Al Stone <al.stone@...aro.org>");
> +MODULE_AUTHOR("Timur Tabi <timur@...eaurora.org>");
> +MODULE_LICENSE("GPL v2");
> --
> 2.5.0
>
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