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Message-ID: <20130322135601.GA11264@roeck-us.net>
Date: Fri, 22 Mar 2013 06:56:01 -0700
From: Guenter Roeck <linux@...ck-us.net>
To: Lubomir Rintel <lkundrak@...sk>
Cc: linux-kernel@...r.kernel.org,
Stephen Warren <swarren@...dotorg.org>,
Wim Van Sebroeck <wim@...ana.be>,
linux-rpi-kernel@...ts.infradead.org,
linux-watchdog@...r.kernel.org
Subject: Re: watchdog: Add Broadcom BCM2708 watchdog timer driver
On Fri, Mar 22, 2013 at 12:55:07PM -0000, Lubomir Rintel wrote:
> Signed-off-by: Lubomir Rintel <lkundrak@...sk>
> Cc: Stephen Warren <swarren@...dotorg.org>
> Cc: Wim Van Sebroeck <wim@...ana.be>
> Cc: linux-rpi-kernel@...ts.infradead.org
> Cc: linux-watchdog@...r.kernel.org
>
> ---
> arch/arm/configs/bcm2835_defconfig | 4 +
> drivers/watchdog/Kconfig | 11 +++
> drivers/watchdog/Makefile | 1 +
> drivers/watchdog/bcm2835_wdt.c | 158 ++++++++++++++++++++++++++++++++++++
> 4 files changed, 174 insertions(+), 0 deletions(-)
> create mode 100644 drivers/watchdog/bcm2835_wdt.c
>
> diff --git a/arch/arm/configs/bcm2835_defconfig b/arch/arm/configs/bcm2835_defconfig
> index 611bda2..8f1547a 100644
> --- a/arch/arm/configs/bcm2835_defconfig
> +++ b/arch/arm/configs/bcm2835_defconfig
> @@ -67,6 +67,10 @@ CONFIG_I2C_BCM2835=y
> CONFIG_GPIO_SYSFS=y
> # CONFIG_HWMON is not set
> # CONFIG_USB_SUPPORT is not set
> +CONFIG_WATCHDOG=y
> +CONFIG_WATCHDOG_CORE=y
> +CONFIG_BCM2835_WDT=y
> +
> CONFIG_MMC=y
> CONFIG_MMC_SDHCI=y
> CONFIG_MMC_SDHCI_PLTFM=y
> diff --git a/drivers/watchdog/Kconfig b/drivers/watchdog/Kconfig
> index 9fcc70c..f4e4a8e 100644
> --- a/drivers/watchdog/Kconfig
> +++ b/drivers/watchdog/Kconfig
> @@ -1098,6 +1098,17 @@ config BCM63XX_WDT
> To compile this driver as a loadable module, choose M here.
> The module will be called bcm63xx_wdt.
>
> +config BCM2835_WDT
> + tristate "Broadcom BCM2835 hardware watchdog"
> + depends on ARCH_BCM2835
> + select WATCHDOG_CORE
> + help
> + Watchdog driver for the built in watchdog hardware in Broadcom
> + BCM2835 SoC.
> +
> + To compile this driver as a loadable module, choose M here.
> + The module will be called bcm2835_wdt.
> +
> config LANTIQ_WDT
> tristate "Lantiq SoC watchdog"
> depends on LANTIQ
> diff --git a/drivers/watchdog/Makefile b/drivers/watchdog/Makefile
> index a300b94..1bf5675 100644
> --- a/drivers/watchdog/Makefile
> +++ b/drivers/watchdog/Makefile
> @@ -54,6 +54,7 @@ obj-$(CONFIG_TS72XX_WATCHDOG) += ts72xx_wdt.o
> obj-$(CONFIG_IMX2_WDT) += imx2_wdt.o
> obj-$(CONFIG_UX500_WATCHDOG) += ux500_wdt.o
> obj-$(CONFIG_RETU_WATCHDOG) += retu_wdt.o
> +obj-$(CONFIG_BCM2835_WDT) += bcm2835_wdt.o
>
> # AVR32 Architecture
> obj-$(CONFIG_AT32AP700X_WDT) += at32ap700x_wdt.o
> diff --git a/drivers/watchdog/bcm2835_wdt.c b/drivers/watchdog/bcm2835_wdt.c
> new file mode 100644
> index 0000000..834f201
> --- /dev/null
> +++ b/drivers/watchdog/bcm2835_wdt.c
> @@ -0,0 +1,158 @@
> +/*
> + * Watchdog driver for Broadcom BCM2835
> + *
> + * Copyright (C) 2013 Lubomir Rintel <lkundrak@...sk>
> + *
> + * 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/types.h>
> +#include <linux/module.h>
> +#include <linux/io.h>
> +#include <linux/watchdog.h>
> +#include <linux/platform_device.h>
> +#include <linux/of_address.h>
> +#include <linux/miscdevice.h>
> +
> +#define PM_RSTC 0x1c
> +#define PM_RSTS 0x20
> +#define PM_WDOG 0x24
> +
> +#define PM_PASSWORD 0x5a000000
> +#define PM_RSTC_WRCFG_MASK 0x00000030
> +#define PM_RSTC_WRCFG_FULL_RESET 0x00000020
> +#define PM_RSTS_HADWRH_SET 0x00000040
> +
> +#define PM_WDOG_TIME_SET 0x000fffff
> +#define PM_RSTC_WRCFG_CLR 0xffffffcf
> +#define PM_RSTC_WRCFG_SET 0x00000030
> +#define PM_RSTC_WRCFG_FULL_RESET 0x00000020
> +#define PM_RSTC_RESET 0x00000102
> +
> +#define SECS_TO_WDOG_TICKS(x) ((x) << 16)
> +#define WDOG_TICKS_TO_SECS(x) ((x) >> 16)
> +
> +static int heartbeat = -1;
> +static bool nowayout = WATCHDOG_NOWAYOUT;
> +static void __iomem *wdt_regs;
> +static DEFINE_SPINLOCK(wdog_lock);
> +
> +static int bcm2835_wdt_start(struct watchdog_device *wdog)
> +{
> + uint32_t cur;
> + unsigned long flags;
> +
> + spin_lock_irqsave(&wdog_lock, flags);
> +
> + writel_relaxed(PM_PASSWORD | (SECS_TO_WDOG_TICKS(wdog->timeout) &
> + PM_WDOG_TIME_SET), wdt_regs + PM_WDOG);
> + cur = readl_relaxed(wdt_regs + PM_RSTC);
> + writel_relaxed(PM_PASSWORD | (cur & PM_RSTC_WRCFG_CLR) |
> + PM_RSTC_WRCFG_FULL_RESET, wdt_regs + PM_RSTC);
> +
Nitpick - I prefer people to use the recommended continuation line style,
but that is really up to the maintainer to decide.
> + spin_unlock_irqrestore(&wdog_lock, flags);
> +
> + return 0;
> +}
> +
> +static int bcm2835_wdt_stop(struct watchdog_device *wdog)
> +{
> + writel_relaxed(PM_PASSWORD | PM_RSTC_RESET, wdt_regs + PM_RSTC);
> + dev_info(wdog->dev, "Watchdog timer stopped");
> + return 0;
> +}
> +
> +static int bcm2835_wdt_set_timeout(struct watchdog_device *wdog, unsigned int t)
> +{
> + wdog->timeout = t;
No need to update the actual chip timeout ?
> + return 0;
> +}
> +
> +static unsigned int bcm2835_wdt_get_timeleft(struct watchdog_device *wdog)
> +{
> + uint32_t ret = readl_relaxed(wdt_regs + PM_WDOG);
> + return WDOG_TICKS_TO_SECS(ret & PM_WDOG_TIME_SET);
> +}
> +
> +static struct watchdog_ops bcm2835_wdt_ops = {
> + .owner = THIS_MODULE,
> + .start = bcm2835_wdt_start,
> + .stop = bcm2835_wdt_stop,
> + .set_timeout = bcm2835_wdt_set_timeout,
> + .get_timeleft = bcm2835_wdt_get_timeleft,
No separate ping function ?
> +};
> +
> +static struct watchdog_info bcm2835_wdt_info = {
> + .options = WDIOF_SETTIMEOUT | WDIOF_MAGICCLOSE |
> + WDIOF_KEEPALIVEPING,
> + .identity = "Broacom BCM2835 Watchdog timer",
> +};
> +
> +static struct watchdog_device bcm2835_wdt_wdd = {
> + .info = &bcm2835_wdt_info,
> + .ops = &bcm2835_wdt_ops,
> + .min_timeout = 1,
> + .max_timeout = WDOG_TICKS_TO_SECS(PM_WDOG_TIME_SET),
> +};
> +
> +static int bcm2835_wdt_probe(struct platform_device *op)
> +{
> + struct device *dev = &op->dev;
> + struct device_node *np = dev->of_node;
> +
> + wdt_regs = of_iomap(np, 0);
> + if (WARN(!wdt_regs, "failed to remap watchdog regs"))
> + return -ENODEV;
WARN seems to be a bit extreme. Is this necessary ?
> + dev_info(dev, "Broadcom BCM2835 watchdog timer");
> +
> + watchdog_init_timeout(&bcm2835_wdt_wdd, heartbeat, dev);
Since heartbeat is by default set to -1, which is interpreted as unsigned
int, I would expect this call to return -EINVAL, leaving the default timeout
undefined. Is this really what you want ?
> + watchdog_set_nowayout(&bcm2835_wdt_wdd, nowayout);
> + return watchdog_register_device(&bcm2835_wdt_wdd);
Leaking iomap if this fails.
Would be nice to have something like devm_of_iomap ...
> +}
> +
> +static int bcm2835_wdt_remove(struct platform_device *op)
> +{
> + watchdog_unregister_device(&bcm2835_wdt_wdd);
> + iounmap(wdt_regs);
> +
> + return 0;
> +}
> +
> +static void bcm2835_wdt_shutdown(struct platform_device *op)
> +{
> + bcm2835_wdt_stop(&bcm2835_wdt_wdd);
> +}
> +
> +static const struct of_device_id bcm2835_wdt_of_match[] = {
> + { .compatible = "brcm,bcm2835-pm-wdt", },
> + {},
> +};
> +MODULE_DEVICE_TABLE(of, bcm2835_wdt_of_match);
> +
> +static struct platform_driver bcm2835_wdt_driver = {
> + .probe = bcm2835_wdt_probe,
> + .remove = bcm2835_wdt_remove,
> + .shutdown = bcm2835_wdt_shutdown,
> + .driver = {
> + .name = "bcm2835-wdt",
> + .owner = THIS_MODULE,
> + .of_match_table = bcm2835_wdt_of_match,
> + },
> +};
> +
> +module_platform_driver(bcm2835_wdt_driver);
> +
> +module_param(heartbeat, int, 0);
> +MODULE_PARM_DESC(heartbeat, "Initial watchdog heartbeat in seconds");
> +
> +module_param(nowayout, bool, 0);
> +MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="
> + __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
> +
> +MODULE_AUTHOR("Lubomir Rintel <lkundrak@...sk>");
> +MODULE_DESCRIPTION("Driver for Broadcom BCM2835 watchdog timer");
> +MODULE_LICENSE("GPL");
> +MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
--
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