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Message-ID: <20130326210348.GA23436@roeck-us.net>
Date: Tue, 26 Mar 2013 14:03:48 -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: [PATCH v3] watchdog: Add Broadcom BCM2835 watchdog timer driver
On Tue, Mar 26, 2013 at 06:50:00PM +0100, Lubomir Rintel wrote:
> This adds a driver for watchdog timer hardware present on Broadcom BCM2835 SoC,
> used in Raspberry Pi and Roku 2 devices.
>
> Signed-off-by: Lubomir Rintel <lkundrak@...sk>
> Cc: Stephen Warren <swarren@...dotorg.org>
> Cc: Wim Van Sebroeck <wim@...ana.be>
> Cc: Guenter Roeck <linux@...ck-us.net>
> Cc: linux-rpi-kernel@...ts.infradead.org
> Cc: linux-watchdog@...r.kernel.org
> ---
> Changes for v2:
> - Use per-device structure instead of global variables for lock and memory base
> - Fix default timeout setting
> - Do not leak memory if probe fails
> - Style fixes
> - Split out defconfig into a separate commit
> - Meaningful commit message with credit
>
> Changes for v3:
> - Add proper copyright notice to header
> - Drop status constants, we don't use them
> - Fix heartbeat parameter's type
> - Log driver initialization message once the device is probed
>
> .../bindings/watchdog/brcm,bcm2835-pm-wdog.txt | 5 +
> drivers/watchdog/Kconfig | 11 ++
> drivers/watchdog/Makefile | 1 +
> drivers/watchdog/bcm2835_wdt.c | 190 ++++++++++++++++++++
> 4 files changed, 207 insertions(+), 0 deletions(-)
> create mode 100644 drivers/watchdog/bcm2835_wdt.c
>
> diff --git a/Documentation/devicetree/bindings/watchdog/brcm,bcm2835-pm-wdog.txt b/Documentation/devicetree/bindings/watchdog/brcm,bcm2835-pm-wdog.txt
> index d209366..f801d71 100644
> --- a/Documentation/devicetree/bindings/watchdog/brcm,bcm2835-pm-wdog.txt
> +++ b/Documentation/devicetree/bindings/watchdog/brcm,bcm2835-pm-wdog.txt
> @@ -5,9 +5,14 @@ Required properties:
> - compatible : should be "brcm,bcm2835-pm-wdt"
> - reg : Specifies base physical address and size of the registers.
>
> +Optional properties:
> +
> +- timeout-sec : Contains the watchdog timeout in seconds
> +
> Example:
>
> watchdog {
> compatible = "brcm,bcm2835-pm-wdt";
> reg = <0x7e100000 0x28>;
> + timeout-sec = <10>;
> };
> 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..13a8c00
> --- /dev/null
> +++ b/drivers/watchdog/bcm2835_wdt.c
> @@ -0,0 +1,190 @@
> +/*
> + * Watchdog driver for Broadcom BCM2835
> + *
> + * Interface to the Broadcom BCM2835 watchdog timer hardware is based on
> + * "bcm2708_wdog" driver written by Luke Diamand that was obtained from branch
> + * "rpi-3.6.y" of git://github.com/raspberrypi/linux.git
> + *
> + * (c) Copyright 2010 Broadcom Europe Ltd
> + * 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_WDOG 0x24
> +
> +#define PM_PASSWORD 0x5a000000
> +
> +#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)
> +
> +struct bcm2835_wdt {
> + void __iomem *base;
> + spinlock_t lock;
> +};
> +
> +static unsigned int heartbeat = 0;
checkpatch.pl says:
ERROR: do not initialise statics to 0 or NULL
#178: FILE: drivers/watchdog/bcm2835_wdt.c:44:
+static unsigned int heartbeat = 0;
> +static bool nowayout = WATCHDOG_NOWAYOUT;
> +
> +static int bcm2835_wdt_start(struct watchdog_device *wdog)
> +{
> + struct bcm2835_wdt *wdt = watchdog_get_drvdata(wdog);
> + uint32_t cur;
> + unsigned long flags;
> +
> + spin_lock_irqsave(&wdt->lock, flags);
> +
> + writel_relaxed(PM_PASSWORD | (SECS_TO_WDOG_TICKS(wdog->timeout) &
> + PM_WDOG_TIME_SET), wdt->base + PM_WDOG);
> + cur = readl_relaxed(wdt->base + PM_RSTC);
> + writel_relaxed(PM_PASSWORD | (cur & PM_RSTC_WRCFG_CLR) |
> + PM_RSTC_WRCFG_FULL_RESET, wdt->base + PM_RSTC);
> +
> + spin_unlock_irqrestore(&wdt->lock, flags);
> +
> + return 0;
> +}
> +
> +static int bcm2835_wdt_stop(struct watchdog_device *wdog)
> +{
> + struct bcm2835_wdt *wdt = watchdog_get_drvdata(wdog);
> +
> + writel_relaxed(PM_PASSWORD | PM_RSTC_RESET, wdt->base + 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;
> + return 0;
> +}
> +
> +static unsigned int bcm2835_wdt_get_timeleft(struct watchdog_device *wdog)
> +{
> + struct bcm2835_wdt *wdt = watchdog_get_drvdata(wdog);
> +
> + uint32_t ret = readl_relaxed(wdt->base + 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,
> +};
> +
> +static struct watchdog_info bcm2835_wdt_info = {
> + .options = WDIOF_SETTIMEOUT | WDIOF_MAGICCLOSE |
> + WDIOF_KEEPALIVEPING,
> + .identity = "Broadcom 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),
> + .timeout = WDOG_TICKS_TO_SECS(PM_WDOG_TIME_SET),
> +};
> +
> +static int bcm2835_wdt_probe(struct platform_device *pdev)
> +{
> + struct device *dev = &pdev->dev;
> + struct device_node *np = dev->of_node;
> + struct bcm2835_wdt *wdt;
> + int err;
> +
> + wdt = devm_kzalloc(dev, sizeof(struct bcm2835_wdt), GFP_KERNEL);
> + if (!wdt) {
> + dev_err(dev, "Failed to allocate memory for watchdog device");
> + return -ENOMEM;
> + }
> +
> + spin_lock_init(&wdt->lock);
> +
> + wdt->base = of_iomap(np, 0);
> + if (!wdt->base) {
> + dev_err(dev, "Failed to remap watchdog regs");
> + return -ENODEV;
> + }
> +
> + platform_set_drvdata(pdev, wdt);
> + watchdog_set_drvdata(&bcm2835_wdt_wdd, wdt);
> + watchdog_init_timeout(&bcm2835_wdt_wdd, heartbeat, dev);
> + watchdog_set_nowayout(&bcm2835_wdt_wdd, nowayout);
> + err = watchdog_register_device(&bcm2835_wdt_wdd);
> + if (err) {
> + dev_err(dev, "Failed to register watchdog device");
> + iounmap(wdt->base);
> + }
> + dev_info(dev, "Broadcom BCM2835 watchdog timer");
> +
Hmm .. that means you'll get the info message even in the error case.
Is that intentional ? It is inconsistent with the remap error message
above, which does not result in the info message.
> + return err;
> +}
> +
> +static int bcm2835_wdt_remove(struct platform_device *pdev)
> +{
> + struct bcm2835_wdt *wdt = platform_get_drvdata(pdev);
> +
> + platform_set_drvdata(pdev, NULL);
Still unnecessary.
Thanks,
Guenter
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