Message-ID: <20211028182005.GE705675@roeck-us.net>
Date:   Thu, 28 Oct 2021 11:20:05 -0700
From:   Guenter Roeck <linux@...ck-us.net>
To:     Florian Fainelli <f.fainelli@...il.com>
Cc:     linux-kernel@...r.kernel.org, rafal@...ecki.pl,
        Wim Van Sebroeck <wim@...ux-watchdog.org>,
        Rob Herring <robh+dt@...nel.org>,
        Thomas Bogendoerfer <tsbogend@...ha.franken.de>,
        "maintainer:BROADCOM BCM63XX ARM ARCHITECTURE" 
        <bcm-kernel-feedback-list@...adcom.com>,
        Justin Chen <justinpopo6@...il.com>,
        "open list:WATCHDOG DEVICE DRIVERS" <linux-watchdog@...r.kernel.org>,
        "open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS" 
        <devicetree@...r.kernel.org>,
        "open list:MIPS" <linux-mips@...r.kernel.org>,
        "moderated list:BROADCOM BCM63XX ARM ARCHITECTURE" 
        <linux-arm-kernel@...ts.infradead.org>
Subject: Re: [PATCH 7/7] watchdog: Remove BCM63XX_WDT

On Thu, Oct 28, 2021 at 10:23:22AM -0700, Florian Fainelli wrote:
> Now that we can utilize the BCM7038_WDT driver, remove that one which
> was not converted to the watchdog APIs. There are a couple of notable
> differences with how the bcm7038_wdt driver proceeds:
> 
> - bcm63xx_wdt would register with the ad-hoc BCM63xx hardware timer API,
>   but this would only be used in order to catch the interrupt *before* a
>   SoC reset and make the kernel "die"
> 
> - bcm6xx_wdt would register a software timer and kick it every second in
>   order to pet the watchdog, thus offering a two step watchdog process.
>   This is not something that is brought over to the bcm7038_wdt as it is
>   deemed unnecessary. If user-space cannot pet the watchdog, but a
>   kernel timer can, the system is still in a bad shape anyway.
> 
> bcm7038_wdt is simpler in its behavior and behaves as a standard
> watchdog driver and is not making use of any specific platform APIs,
> therefore making it more maintainable and extensible.
> 
> Signed-off-by: Florian Fainelli <f.fainelli@...il.com>

Reviewed-by: Guenter Roeck <linux@...ck-us.net>

> ---
>  drivers/watchdog/Kconfig       |  10 --
>  drivers/watchdog/Makefile      |   1 -
>  drivers/watchdog/bcm63xx_wdt.c | 315 ---------------------------------
>  3 files changed, 326 deletions(-)
>  delete mode 100644 drivers/watchdog/bcm63xx_wdt.c
> 
> diff --git a/drivers/watchdog/Kconfig b/drivers/watchdog/Kconfig
> index 24a775dd2bf1..acebf9caf6d1 100644
> --- a/drivers/watchdog/Kconfig
> +++ b/drivers/watchdog/Kconfig
> @@ -1709,16 +1709,6 @@ config OCTEON_WDT
>  	  from the first interrupt, it is then only poked when the
>  	  device is written.
>  
> -config BCM63XX_WDT
> -	tristate "Broadcom BCM63xx hardware watchdog"
> -	depends on BCM63XX
> -	help
> -	  Watchdog driver for the built in watchdog hardware in Broadcom
> -	  BCM63xx SoC.
> -
> -	  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 || (OF && COMPILE_TEST)
> diff --git a/drivers/watchdog/Makefile b/drivers/watchdog/Makefile
> index 1bd2d6f37c53..9811c4b1cd16 100644
> --- a/drivers/watchdog/Makefile
> +++ b/drivers/watchdog/Makefile
> @@ -154,7 +154,6 @@ obj-$(CONFIG_XILINX_WATCHDOG) += of_xilinx_wdt.o
>  # MIPS Architecture
>  obj-$(CONFIG_ATH79_WDT) += ath79_wdt.o
>  obj-$(CONFIG_BCM47XX_WDT) += bcm47xx_wdt.o
> -obj-$(CONFIG_BCM63XX_WDT) += bcm63xx_wdt.o
>  obj-$(CONFIG_RC32434_WDT) += rc32434_wdt.o
>  obj-$(CONFIG_INDYDOG) += indydog.o
>  obj-$(CONFIG_JZ4740_WDT) += jz4740_wdt.o
> diff --git a/drivers/watchdog/bcm63xx_wdt.c b/drivers/watchdog/bcm63xx_wdt.c
> deleted file mode 100644
> index 7cdb25363ea0..000000000000
> --- a/drivers/watchdog/bcm63xx_wdt.c
> +++ /dev/null
> @@ -1,315 +0,0 @@
> -// SPDX-License-Identifier: GPL-2.0+
> -/*
> - *  Broadcom BCM63xx SoC watchdog driver
> - *
> - *  Copyright (C) 2007, Miguel Gaio <miguel.gaio@...xo.com>
> - *  Copyright (C) 2008, Florian Fainelli <florian@...nwrt.org>
> - *
> - */
> -
> -#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
> -
> -#include <linux/bitops.h>
> -#include <linux/errno.h>
> -#include <linux/fs.h>
> -#include <linux/io.h>
> -#include <linux/kernel.h>
> -#include <linux/miscdevice.h>
> -#include <linux/module.h>
> -#include <linux/moduleparam.h>
> -#include <linux/types.h>
> -#include <linux/uaccess.h>
> -#include <linux/watchdog.h>
> -#include <linux/timer.h>
> -#include <linux/jiffies.h>
> -#include <linux/interrupt.h>
> -#include <linux/ptrace.h>
> -#include <linux/resource.h>
> -#include <linux/platform_device.h>
> -
> -#include <bcm63xx_cpu.h>
> -#include <bcm63xx_io.h>
> -#include <bcm63xx_regs.h>
> -#include <bcm63xx_timer.h>
> -
> -#define PFX KBUILD_MODNAME
> -
> -#define WDT_HZ		50000000 /* Fclk */
> -#define WDT_DEFAULT_TIME	30      /* seconds */
> -#define WDT_MAX_TIME		256     /* seconds */
> -
> -static struct {
> -	void __iomem *regs;
> -	struct timer_list timer;
> -	unsigned long inuse;
> -	atomic_t ticks;
> -} bcm63xx_wdt_device;
> -
> -static int expect_close;
> -
> -static int wdt_time = WDT_DEFAULT_TIME;
> -static bool nowayout = WATCHDOG_NOWAYOUT;
> -module_param(nowayout, bool, 0);
> -MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="
> -	__MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
> -
> -/* HW functions */
> -static void bcm63xx_wdt_hw_start(void)
> -{
> -	bcm_writel(0xfffffffe, bcm63xx_wdt_device.regs + WDT_DEFVAL_REG);
> -	bcm_writel(WDT_START_1, bcm63xx_wdt_device.regs + WDT_CTL_REG);
> -	bcm_writel(WDT_START_2, bcm63xx_wdt_device.regs + WDT_CTL_REG);
> -}
> -
> -static void bcm63xx_wdt_hw_stop(void)
> -{
> -	bcm_writel(WDT_STOP_1, bcm63xx_wdt_device.regs + WDT_CTL_REG);
> -	bcm_writel(WDT_STOP_2, bcm63xx_wdt_device.regs + WDT_CTL_REG);
> -}
> -
> -static void bcm63xx_wdt_isr(void *data)
> -{
> -	struct pt_regs *regs = get_irq_regs();
> -
> -	die(PFX " fire", regs);
> -}
> -
> -static void bcm63xx_timer_tick(struct timer_list *unused)
> -{
> -	if (!atomic_dec_and_test(&bcm63xx_wdt_device.ticks)) {
> -		bcm63xx_wdt_hw_start();
> -		mod_timer(&bcm63xx_wdt_device.timer, jiffies + HZ);
> -	} else
> -		pr_crit("watchdog will restart system\n");
> -}
> -
> -static void bcm63xx_wdt_pet(void)
> -{
> -	atomic_set(&bcm63xx_wdt_device.ticks, wdt_time);
> -}
> -
> -static void bcm63xx_wdt_start(void)
> -{
> -	bcm63xx_wdt_pet();
> -	bcm63xx_timer_tick(0);
> -}
> -
> -static void bcm63xx_wdt_pause(void)
> -{
> -	del_timer_sync(&bcm63xx_wdt_device.timer);
> -	bcm63xx_wdt_hw_stop();
> -}
> -
> -static int bcm63xx_wdt_settimeout(int new_time)
> -{
> -	if ((new_time <= 0) || (new_time > WDT_MAX_TIME))
> -		return -EINVAL;
> -
> -	wdt_time = new_time;
> -
> -	return 0;
> -}
> -
> -static int bcm63xx_wdt_open(struct inode *inode, struct file *file)
> -{
> -	if (test_and_set_bit(0, &bcm63xx_wdt_device.inuse))
> -		return -EBUSY;
> -
> -	bcm63xx_wdt_start();
> -	return stream_open(inode, file);
> -}
> -
> -static int bcm63xx_wdt_release(struct inode *inode, struct file *file)
> -{
> -	if (expect_close == 42)
> -		bcm63xx_wdt_pause();
> -	else {
> -		pr_crit("Unexpected close, not stopping watchdog!\n");
> -		bcm63xx_wdt_start();
> -	}
> -	clear_bit(0, &bcm63xx_wdt_device.inuse);
> -	expect_close = 0;
> -	return 0;
> -}
> -
> -static ssize_t bcm63xx_wdt_write(struct file *file, const char *data,
> -				size_t len, loff_t *ppos)
> -{
> -	if (len) {
> -		if (!nowayout) {
> -			size_t i;
> -
> -			/* In case it was set long ago */
> -			expect_close = 0;
> -
> -			for (i = 0; i != len; i++) {
> -				char c;
> -				if (get_user(c, data + i))
> -					return -EFAULT;
> -				if (c == 'V')
> -					expect_close = 42;
> -			}
> -		}
> -		bcm63xx_wdt_pet();
> -	}
> -	return len;
> -}
> -
> -static struct watchdog_info bcm63xx_wdt_info = {
> -	.identity       = PFX,
> -	.options        = WDIOF_SETTIMEOUT |
> -				WDIOF_KEEPALIVEPING |
> -				WDIOF_MAGICCLOSE,
> -};
> -
> -
> -static long bcm63xx_wdt_ioctl(struct file *file, unsigned int cmd,
> -				unsigned long arg)
> -{
> -	void __user *argp = (void __user *)arg;
> -	int __user *p = argp;
> -	int new_value, retval = -EINVAL;
> -
> -	switch (cmd) {
> -	case WDIOC_GETSUPPORT:
> -		return copy_to_user(argp, &bcm63xx_wdt_info,
> -			sizeof(bcm63xx_wdt_info)) ? -EFAULT : 0;
> -
> -	case WDIOC_GETSTATUS:
> -	case WDIOC_GETBOOTSTATUS:
> -		return put_user(0, p);
> -
> -	case WDIOC_SETOPTIONS:
> -		if (get_user(new_value, p))
> -			return -EFAULT;
> -
> -		if (new_value & WDIOS_DISABLECARD) {
> -			bcm63xx_wdt_pause();
> -			retval = 0;
> -		}
> -		if (new_value & WDIOS_ENABLECARD) {
> -			bcm63xx_wdt_start();
> -			retval = 0;
> -		}
> -
> -		return retval;
> -
> -	case WDIOC_KEEPALIVE:
> -		bcm63xx_wdt_pet();
> -		return 0;
> -
> -	case WDIOC_SETTIMEOUT:
> -		if (get_user(new_value, p))
> -			return -EFAULT;
> -
> -		if (bcm63xx_wdt_settimeout(new_value))
> -			return -EINVAL;
> -
> -		bcm63xx_wdt_pet();
> -
> -	case WDIOC_GETTIMEOUT:
> -		return put_user(wdt_time, p);
> -
> -	default:
> -		return -ENOTTY;
> -
> -	}
> -}
> -
> -static const struct file_operations bcm63xx_wdt_fops = {
> -	.owner		= THIS_MODULE,
> -	.llseek		= no_llseek,
> -	.write		= bcm63xx_wdt_write,
> -	.unlocked_ioctl	= bcm63xx_wdt_ioctl,
> -	.compat_ioctl	= compat_ptr_ioctl,
> -	.open		= bcm63xx_wdt_open,
> -	.release	= bcm63xx_wdt_release,
> -};
> -
> -static struct miscdevice bcm63xx_wdt_miscdev = {
> -	.minor	= WATCHDOG_MINOR,
> -	.name	= "watchdog",
> -	.fops	= &bcm63xx_wdt_fops,
> -};
> -
> -
> -static int bcm63xx_wdt_probe(struct platform_device *pdev)
> -{
> -	int ret;
> -	struct resource *r;
> -
> -	timer_setup(&bcm63xx_wdt_device.timer, bcm63xx_timer_tick, 0);
> -
> -	r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> -	if (!r) {
> -		dev_err(&pdev->dev, "failed to get resources\n");
> -		return -ENODEV;
> -	}
> -
> -	bcm63xx_wdt_device.regs = devm_ioremap(&pdev->dev, r->start,
> -							resource_size(r));
> -	if (!bcm63xx_wdt_device.regs) {
> -		dev_err(&pdev->dev, "failed to remap I/O resources\n");
> -		return -ENXIO;
> -	}
> -
> -	ret = bcm63xx_timer_register(TIMER_WDT_ID, bcm63xx_wdt_isr, NULL);
> -	if (ret < 0) {
> -		dev_err(&pdev->dev, "failed to register wdt timer isr\n");
> -		return ret;
> -	}
> -
> -	if (bcm63xx_wdt_settimeout(wdt_time)) {
> -		bcm63xx_wdt_settimeout(WDT_DEFAULT_TIME);
> -		dev_info(&pdev->dev,
> -			": wdt_time value must be 1 <= wdt_time <= 256, using %d\n",
> -			wdt_time);
> -	}
> -
> -	ret = misc_register(&bcm63xx_wdt_miscdev);
> -	if (ret < 0) {
> -		dev_err(&pdev->dev, "failed to register watchdog device\n");
> -		goto unregister_timer;
> -	}
> -
> -	dev_info(&pdev->dev, " started, timer margin: %d sec\n",
> -						WDT_DEFAULT_TIME);
> -
> -	return 0;
> -
> -unregister_timer:
> -	bcm63xx_timer_unregister(TIMER_WDT_ID);
> -	return ret;
> -}
> -
> -static int bcm63xx_wdt_remove(struct platform_device *pdev)
> -{
> -	if (!nowayout)
> -		bcm63xx_wdt_pause();
> -
> -	misc_deregister(&bcm63xx_wdt_miscdev);
> -	bcm63xx_timer_unregister(TIMER_WDT_ID);
> -	return 0;
> -}
> -
> -static void bcm63xx_wdt_shutdown(struct platform_device *pdev)
> -{
> -	bcm63xx_wdt_pause();
> -}
> -
> -static struct platform_driver bcm63xx_wdt_driver = {
> -	.probe	= bcm63xx_wdt_probe,
> -	.remove = bcm63xx_wdt_remove,
> -	.shutdown = bcm63xx_wdt_shutdown,
> -	.driver = {
> -		.name = "bcm63xx-wdt",
> -	}
> -};
> -
> -module_platform_driver(bcm63xx_wdt_driver);
> -
> -MODULE_AUTHOR("Miguel Gaio <miguel.gaio@...xo.com>");
> -MODULE_AUTHOR("Florian Fainelli <florian@...nwrt.org>");
> -MODULE_DESCRIPTION("Driver for the Broadcom BCM63xx SoC watchdog");
> -MODULE_LICENSE("GPL");
> -MODULE_ALIAS("platform:bcm63xx-wdt");
> -- 
> 2.25.1
> 

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