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Date: Fri, 21 Oct 2016 07:23:21 -0700
From: Guenter Roeck <linux@...ck-us.net>
To: Yang Ling <gnaygnil@...il.com>, Wim Van Sebroeck <wim@...ana.be>,
Keguang Zhang <keguang.zhang@...il.com>
Cc: linux-kernel@...r.kernel.org, linux-watchdog@...r.kernel.org,
linux-mips@...ux-mips.org
Subject: Re: [PATCH v2.1 1/2] watchdog: loongson1: Add Loongson1 SoC watchdog
driver
On 10/20/2016 10:45 PM, Yang Ling wrote:
> Add watchdog timer specific driver for Loongson1 SoC.
>
> Signed-off-by: Yang Ling <gnaygnil@...il.com>
>
> ---
> V2.1 from Kelvin Cheung:
> Use max_hw_heartbeat_ms instead of max_timeout.
> V2:
> Increase the value of the default heartbeat.
> Modify the setup process for register.
> Order include files and Makefile alphabetically.
> V1.1:
> Add a little debugging information.
> ---
> drivers/watchdog/Kconfig | 7 ++
> drivers/watchdog/Makefile | 1 +
> drivers/watchdog/loongson1_wdt.c | 158 +++++++++++++++++++++++++++++++++++++++
> 3 files changed, 166 insertions(+)
> create mode 100644 drivers/watchdog/loongson1_wdt.c
>
> diff --git a/drivers/watchdog/Kconfig b/drivers/watchdog/Kconfig
> index 50dbaa8..6707d43 100644
> --- a/drivers/watchdog/Kconfig
> +++ b/drivers/watchdog/Kconfig
> @@ -1513,6 +1513,13 @@ config LANTIQ_WDT
> help
> Hardware driver for the Lantiq SoC Watchdog Timer.
>
> +config LOONGSON1_WDT
> + tristate "Loongson1 SoC hardware watchdog"
> + depends on MACH_LOONGSON32
> + select WATCHDOG_CORE
> + help
> + Hardware driver for the Loongson1 SoC Watchdog Timer.
> +
> config RALINK_WDT
> tristate "Ralink SoC watchdog"
> select WATCHDOG_CORE
> diff --git a/drivers/watchdog/Makefile b/drivers/watchdog/Makefile
> index cba0043..b6a8d70 100644
> --- a/drivers/watchdog/Makefile
> +++ b/drivers/watchdog/Makefile
> @@ -157,6 +157,7 @@ obj-$(CONFIG_TXX9_WDT) += txx9wdt.o
> obj-$(CONFIG_OCTEON_WDT) += octeon-wdt.o
> octeon-wdt-y := octeon-wdt-main.o octeon-wdt-nmi.o
> obj-$(CONFIG_LANTIQ_WDT) += lantiq_wdt.o
> +obj-$(CONFIG_LOONGSON1_WDT) += loongson1_wdt.o
> obj-$(CONFIG_RALINK_WDT) += rt2880_wdt.o
> obj-$(CONFIG_IMGPDC_WDT) += imgpdc_wdt.o
> obj-$(CONFIG_MT7621_WDT) += mt7621_wdt.o
> diff --git a/drivers/watchdog/loongson1_wdt.c b/drivers/watchdog/loongson1_wdt.c
> new file mode 100644
> index 0000000..f885294
> --- /dev/null
> +++ b/drivers/watchdog/loongson1_wdt.c
> @@ -0,0 +1,158 @@
> +/*
> + * Copyright (c) 2016 Yang Ling <gnaygnil@...il.com>
> + *
> + * 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.
Odd spacing.
> + */
> +
> +#include <linux/clk.h>
> +#include <linux/module.h>
> +#include <linux/platform_device.h>
> +#include <linux/watchdog.h>
> +#include <loongson1.h>
> +
> +#define DEFAULT_HEARTBEAT 30
> +
> +static bool nowayout = WATCHDOG_NOWAYOUT;
> +module_param(nowayout, bool, 0444);
> +
> +static unsigned int heartbeat = DEFAULT_HEARTBEAT;
> +module_param(heartbeat, uint, 0444);
> +
> +struct ls1x_wdt_drvdata {
> + void __iomem *base;
> + struct clk *clk;
> + unsigned int counts_per_second;
> + struct watchdog_device wdt;
> +};
> +
> +static int ls1x_wdt_ping(struct watchdog_device *wdt_dev)
> +{
> + struct ls1x_wdt_drvdata *drvdata = watchdog_get_drvdata(wdt_dev);
> +
> + writel(0x1, drvdata->base + WDT_SET);
> +
> + return 0;
> +}
> +
> +static int ls1x_wdt_set_timeout(struct watchdog_device *wdt_dev,
> + unsigned int timeout)
> +{
> + struct ls1x_wdt_drvdata *drvdata = watchdog_get_drvdata(wdt_dev);
> + unsigned int counts;
> +
> + wdt_dev->timeout = min(timeout, wdt_dev->max_hw_heartbeat_ms / 1000);
The point of using max_hw_heartbeat_ms is that the watchdog core takes care of
timeouts larger than the maximum supported by the hardware. What you should do
here is something along the line of
wdt_dev->timeout = timeout;
counts = drvdata->counts_per_second * min(timeout, wdt_dev->max_hw_heartbeat_ms / 1000);
> + counts = drvdata->counts_per_second * wdt_dev->timeout;
> +
> + writel(counts, drvdata->base + WDT_TIMER);
> +
> + return 0;
> +}
> +
> +static int ls1x_wdt_start(struct watchdog_device *wdt_dev)
> +{
> + struct ls1x_wdt_drvdata *drvdata = watchdog_get_drvdata(wdt_dev);
> +
> + writel(0x1, drvdata->base + WDT_EN);
> +
> + return 0;
> +}
> +
> +static int ls1x_wdt_stop(struct watchdog_device *wdt_dev)
> +{
> + struct ls1x_wdt_drvdata *drvdata = watchdog_get_drvdata(wdt_dev);
> +
> + writel(0x0, drvdata->base + WDT_EN);
> +
> + return 0;
> +}
> +
> +static const struct watchdog_info ls1x_wdt_info = {
> + .options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE,
> + .identity = "Loongson1 Watchdog",
> +};
> +
> +static const struct watchdog_ops ls1x_wdt_ops = {
> + .owner = THIS_MODULE,
> + .start = ls1x_wdt_start,
> + .stop = ls1x_wdt_stop,
> + .ping = ls1x_wdt_ping,
> + .set_timeout = ls1x_wdt_set_timeout,
> +};
> +
> +static int ls1x_wdt_probe(struct platform_device *pdev)
> +{
> + struct ls1x_wdt_drvdata *drvdata;
> + struct watchdog_device *ls1x_wdt;
> + struct resource *res;
> + int ret;
> +
> + drvdata = devm_kzalloc(&pdev->dev, sizeof(*drvdata), GFP_KERNEL);
> + if (!drvdata)
> + return -ENOMEM;
> +
> + res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> + drvdata->base = devm_ioremap_resource(&pdev->dev, res);
> + if (IS_ERR(drvdata->base))
> + return PTR_ERR(drvdata->base);
> +
> + drvdata->clk = devm_clk_get(&pdev->dev, pdev->name);
> + if (IS_ERR(drvdata->clk)) {
> + dev_err(&pdev->dev, "failed to get %s clock\n", pdev->name);
> + return PTR_ERR(drvdata->clk);
> + }
> + clk_prepare_enable(drvdata->clk);
> +
> + drvdata->counts_per_second = clk_get_rate(drvdata->clk);
clk_get_rate() can at least in theory return 0,
> +
> + ls1x_wdt = &drvdata->wdt;
> + ls1x_wdt->info = &ls1x_wdt_info;
> + ls1x_wdt->ops = &ls1x_wdt_ops;
> + ls1x_wdt->min_timeout = 1;
> + ls1x_wdt->max_hw_heartbeat_ms = U32_MAX / drvdata->counts_per_second *
> + 1000;
which would result in a crash here.
> + ls1x_wdt->parent = &pdev->dev;
> +
> + watchdog_init_timeout(ls1x_wdt, heartbeat, &pdev->dev);
> + watchdog_set_nowayout(ls1x_wdt, nowayout);
> + watchdog_set_drvdata(ls1x_wdt, drvdata);
> +
> + ret = watchdog_register_device(&drvdata->wdt);
> + if (ret < 0) {
> + dev_err(&pdev->dev, "failed to register watchdog device\n");
> + return ret;
> + }
> +
> + platform_set_drvdata(pdev, drvdata);
> +
> + dev_info(&pdev->dev, "Loongson1 Watchdog driver registered\n");
> +
> + return 0;
> +}
> +
> +static int ls1x_wdt_remove(struct platform_device *pdev)
> +{
> + struct ls1x_wdt_drvdata *drvdata = platform_get_drvdata(pdev);
> +
> + ls1x_wdt_stop(&drvdata->wdt);
This should not be necessary. If the watchdog device is open (meaning the
watchdog may be running), you should not be able to unload the driver.
Can you test ?
> + watchdog_unregister_device(&drvdata->wdt);
> + clk_disable_unprepare(drvdata->clk);
> +
> + return 0;
> +}
> +
> +static struct platform_driver ls1x_wdt_driver = {
> + .probe = ls1x_wdt_probe,
> + .remove = ls1x_wdt_remove,
> + .driver = {
> + .name = "ls1x-wdt",
> + },
> +};
> +
> +module_platform_driver(ls1x_wdt_driver);
> +
> +MODULE_AUTHOR("Yang Ling <gnaygnil@...il.com>");
> +MODULE_DESCRIPTION("Loongson1 Watchdog Driver");
> +MODULE_LICENSE("GPL");
>
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