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Date: Thu, 13 Jun 2013 20:55:33 -0700
From: Guenter Roeck <linux@...ck-us.net>
To: Johannes Thumshirn <johannes.thumshirn@....de>
Cc: wim@...ana.be, linux-kernel@...r.kernel.org,
linux-watchdog@...r.kernel.org, guenter@...ck-us.net
Subject: Re: [PATCH v8] watchdog: New watchdog driver for MEN A21 watchdogs
On Mon, Jun 03, 2013 at 04:34:59PM +0200, Johannes Thumshirn wrote:
> This patch adds the driver for the watchdog devices found on MEN Mikro
> Elektronik A21 VMEbus CPU Carrier Boards. It has DT-support and uses the
> watchdog framework.
>
> Revision 2:
> * Removed unneeded open flag in struct a21_wdt_drv
> * Corrected 3bit reason code from gpio
> * Additional sysfs files are now part of watchdog sysfs
> * Changed OFF/ON delay in ping from 400ms to 10ns
> * Reworked timeout setting
> * Removed a21_wdt_ioctl(...)
>
> Revision 3:
> * Changed pr_{err,info} to dev_{err,info}
> * Removed out of memory error print
> * Transition from "fast" to "slow" mode not allowed by chip
>
> Revision 4:
> * Remove reboot_notifier and place disable code into platform_device's shutdown function
> * Removed sysfs interface
>
> Revision 5:
> * Added setting of .bootstatus on driver init
> * Added initial timeout on driver init
>
> Revision 6:
> * Use watchdog_init_timeout() to initialize timeout
>
> Revision 7:
> * Fix possible get_bootstatus race condition
>
> Revision 8:
> * a21_wdt_get_bootstatus() should return reset code
> * GPIOs are supplied via DT instead of being hardcoded. Code derived from
> (drivers/hwmon/gpio-fan.c)
> * Added Devicetree binding document
> * Driver now depends on GPIOLIB
>
> Signed-off-by: Johannes Thumshirn <johannes.thumshirn@....de>
Almost good. One comment below.
Thanks,
Guenter
> ---
> .../devicetree/bindings/gpio/men-a021-wdt.txt | 25 ++
> MAINTAINERS | 6 +
> drivers/watchdog/Kconfig | 12 +
> drivers/watchdog/Makefile | 1 +
> drivers/watchdog/mena21_wdt.c | 277 ++++++++++++++++++++
> 5 files changed, 321 insertions(+)
> create mode 100644 Documentation/devicetree/bindings/gpio/men-a021-wdt.txt
> create mode 100644 drivers/watchdog/mena21_wdt.c
>
> diff --git a/Documentation/devicetree/bindings/gpio/men-a021-wdt.txt b/Documentation/devicetree/bindings/gpio/men-a021-wdt.txt
> new file mode 100644
> index 0000000..370dee3
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/gpio/men-a021-wdt.txt
> @@ -0,0 +1,25 @@
> +Bindings for MEN A21 Watchdog device connected to GPIO lines
> +
> +Required properties:
> +- compatible: "men,a021-wdt"
> +- gpios: Specifies the pins that control the Watchdog, order:
> + 1: Watchdog enable
> + 2: Watchdog fast-mode
> + 3: Watchdog trigger
> + 4: Watchdog reset cause bit 0
> + 5: Watchdog reset cause bit 1
> + 6: Watchdog reset cause bit 2
> +
> +Optional properties:
> +- None
> +
> +Example:
> + watchdog {
> + compatible ="men,a021-wdt";
> + gpios = <&gpio3 9 1 /* WD_EN */
> + &gpio3 10 1 /* WD_FAST */
> + &gpio3 11 1 /* WD_TRIG */
> + &gpio3 6 1 /* RST_CAUSE[0] */
> + &gpio3 7 1 /* RST_CAUSE[1] */
> + &gpio3 8 1>; /* RST_CAUSE[2] */
> + };
> diff --git a/MAINTAINERS b/MAINTAINERS
> index f35a259..bd86661 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -5307,6 +5307,12 @@ F: drivers/mtd/
> F: include/linux/mtd/
> F: include/uapi/mtd/
>
> +MEN A21 WATCHDOG DRIVER
> +M: Johannes Thumshirn <johannes.thumshirn@....de>
> +L: linux-watchdog@...r.kernel.org
> +S: Supported
> +F: drivers/watchdog/mena21_wdt.c
> +
> METAG ARCHITECTURE
> M: James Hogan <james.hogan@...tec.com>
> S: Supported
> diff --git a/drivers/watchdog/Kconfig b/drivers/watchdog/Kconfig
> index e89fc31..8b143ee 100644
> --- a/drivers/watchdog/Kconfig
> +++ b/drivers/watchdog/Kconfig
> @@ -1172,6 +1172,18 @@ config BOOKE_WDT_DEFAULT_TIMEOUT
>
> The value can be overridden by the wdt_period command-line parameter.
>
> +config MEN_A21_WDT
> + tristate "MEN A21 VME CPU Carrier Board Watchdog Timer"
> + select WATCHDOG_CORE
> + depends on GPIOLIB
> + help
> + Watchdog driver for MEN A21 VMEbus CPU Carrier Boards.
> +
> + The driver can also be built as a module. If so, the module will be
> + called mena21_wdt.
> +
> + If unsure select N here.
> +
> # PPC64 Architecture
>
> config WATCHDOG_RTAS
> diff --git a/drivers/watchdog/Makefile b/drivers/watchdog/Makefile
> index a300b94..bffdcb1 100644
> --- a/drivers/watchdog/Makefile
> +++ b/drivers/watchdog/Makefile
> @@ -143,6 +143,7 @@ obj-$(CONFIG_8xxx_WDT) += mpc8xxx_wdt.o
> obj-$(CONFIG_MV64X60_WDT) += mv64x60_wdt.o
> obj-$(CONFIG_PIKA_WDT) += pika_wdt.o
> obj-$(CONFIG_BOOKE_WDT) += booke_wdt.o
> +obj-$(CONFIG_MEN_A21_WDT) += mena21_wdt.o
>
> # PPC64 Architecture
> obj-$(CONFIG_WATCHDOG_RTAS) += wdrtas.o
> diff --git a/drivers/watchdog/mena21_wdt.c b/drivers/watchdog/mena21_wdt.c
> new file mode 100644
> index 0000000..29f9c0d
> --- /dev/null
> +++ b/drivers/watchdog/mena21_wdt.c
> @@ -0,0 +1,277 @@
> +/*
> + * Watchdog driver for the A21 VME CPU Boards
> + *
> + * Copyright (C) 2013 MEN Mikro Elektronik Nuernberg GmbH
> + *
> + * 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
> + */
> +#include <linux/module.h>
> +#include <linux/moduleparam.h>
> +#include <linux/types.h>
> +#include <linux/kernel.h>
> +#include <linux/slab.h>
> +#include <linux/platform_device.h>
> +#include <linux/watchdog.h>
> +#include <linux/uaccess.h>
> +#include <linux/gpio.h>
> +#include <linux/of_gpio.h>
> +#include <linux/delay.h>
> +#include <linux/bitops.h>
> +
> +enum a21_wdt_gpios {
> + GPIO_WD_ENAB,
> + GPIO_WD_FAST,
> + GPIO_WD_TRIG,
> + GPIO_WD_RST0,
> + GPIO_WD_RST1,
> + GPIO_WD_RST2,
> +};
> +
> +struct a21_wdt_drv {
> + struct watchdog_device wdt;
> + struct mutex lock;
> + int num_gpios;
> + unsigned *gpios;
> +};
> +
> +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) ")");
> +
> +static unsigned int a21_wdt_get_bootstatus(struct a21_wdt_drv *drv)
> +{
> + int reset = 0;
> +
> + reset |= gpio_get_value(drv->gpios[GPIO_WD_RST0]) ? (1 << 0) : 0;
> + reset |= gpio_get_value(drv->gpios[GPIO_WD_RST1]) ? (1 << 1) : 0;
> + reset |= gpio_get_value(drv->gpios[GPIO_WD_RST2]) ? (1 << 2) : 0;
> +
> + return reset;
> +}
> +
> +static int a21_wdt_start(struct watchdog_device *wdt)
> +{
> + struct a21_wdt_drv *drv = watchdog_get_drvdata(wdt);
> +
> + mutex_lock(&drv->lock);
> +
> + gpio_set_value(drv->gpios[GPIO_WD_ENAB], 1);
> +
> + mutex_unlock(&drv->lock);
> +
> + return 0;
> +}
> +
> +static int a21_wdt_stop(struct watchdog_device *wdt)
> +{
> + struct a21_wdt_drv *drv = watchdog_get_drvdata(wdt);
> +
> + /* We don't stop if WDOG_NO_WAY_OUT is set */
> + if (test_bit(WDOG_NO_WAY_OUT, &wdt->status))
> + return -EINVAL;
> +
> + mutex_lock(&drv->lock);
> +
> + gpio_set_value(drv->gpios[GPIO_WD_ENAB], 0);
> +
> + mutex_unlock(&drv->lock);
> +
> + return 0;
> +}
> +
> +static int a21_wdt_ping(struct watchdog_device *wdt)
> +{
> + struct a21_wdt_drv *drv = watchdog_get_drvdata(wdt);
> +
> + mutex_lock(&drv->lock);
> +
> + gpio_set_value(drv->gpios[GPIO_WD_TRIG], 0);
> + ndelay(10);
> + gpio_set_value(drv->gpios[GPIO_WD_TRIG], 1);
> +
> + mutex_unlock(&drv->lock);
> +
> + return 0;
> +}
> +
> +static int a21_wdt_set_timeout(struct watchdog_device *wdt,
> + unsigned int timeout)
> +{
> + struct a21_wdt_drv *drv = watchdog_get_drvdata(wdt);
> +
> + if (timeout != 1 && timeout != 30) {
> + dev_err(wdt->dev, "Only 1 and 30 allowed as timeout\n");
> + return -EINVAL;
> + }
> +
> + if (timeout == 30 && wdt->timeout == 1) {
> + dev_err(wdt->dev,
> + "Transition from fast to slow mode not allowed\n");
> + return -EINVAL;
> + }
> +
> + mutex_lock(&drv->lock);
> +
> + if (timeout == 1)
> + gpio_set_value(drv->gpios[GPIO_WD_FAST], 1);
> + else
> + gpio_set_value(drv->gpios[GPIO_WD_FAST], 0);
> +
> + wdt->timeout = timeout;
> +
> + mutex_unlock(&drv->lock);
> +
> + return 0;
> +}
> +
> +static const struct watchdog_info a21_wdt_info = {
> + .options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE,
> + .identity = "MEN A21 Watchdog",
> +};
> +
> +static const struct watchdog_ops a21_wdt_ops = {
> + .owner = THIS_MODULE,
> + .start = a21_wdt_start,
> + .stop = a21_wdt_stop,
> + .ping = a21_wdt_ping,
> + .set_timeout = a21_wdt_set_timeout,
> +};
> +
> +static struct watchdog_device a21_wdt = {
> + .info = &a21_wdt_info,
> + .ops = &a21_wdt_ops,
> + .min_timeout = 1,
> + .max_timeout = 30,
> +};
> +
> +static int a21_wdt_probe(struct platform_device *pdev)
> +{
> + struct device_node *node;
> + struct a21_wdt_drv *drv;
> + unsigned int reset = 0;
> + unsigned *gpios;
> + int ret;
> + int i;
> +
> + dev_info(&pdev->dev, "MEN A21 watchdog timer driver enabled\n");
> +
> + drv = devm_kzalloc(&pdev->dev, sizeof(struct a21_wdt_drv), GFP_KERNEL);
> + if (!drv)
> + return -ENOMEM;
> +
> + /* Fill GPIO pin array */
> + node = pdev->dev.of_node;
> +
> + drv->num_gpios = of_gpio_count(node);
> + if (drv->num_gpios <= 0) {
> + dev_err(&pdev->dev, "gpios DT property empty / missing");
> + return -ENODEV;
> + }
Not happy with this. Code accepts one gpio pin, but then assumes throughout the
driver that all pins are defined. I am quite sure I can get it to crash if I
specify only a single gpio pin. num_gpios will be 1, you allocate a single
entry, but then access all 6 of them.
I think it would be easier if you expect a fixed number of gpio pins (6) and abort
if it is not correct. You can then make drv->gpios an array and don't have to
allocate it separately, and you don't need drv->num_gpios (which you don't need
anyway as it is not used outside this function).
> +
> + gpios = devm_kzalloc(&pdev->dev, drv->num_gpios * sizeof(unsigned),
> + GFP_KERNEL);
> + if (!gpios)
> + return -ENOMEM;
> +
> + for (i = 0; i < drv->num_gpios; i++) {
> + int val;
> +
> + val = of_get_gpio(node, i);
> + if (val < 0)
> + return val;
> +
> + gpios[i] = val;
> + }
> + drv->gpios = gpios;
> +
> + /* Request the used GPIOs */
> + for (i = 0; i < drv->num_gpios; i++) {
> + ret = devm_gpio_request(&pdev->dev, drv->gpios[i],
> + "MEN A21 Watchdog");
> + if (ret)
> + return ret;
> +
> + ret = gpio_direction_output(drv->gpios[i],
> + gpio_get_value(drv->gpios[i]));
> + if (ret)
> + return ret;
> + }
> +
> + mutex_init(&drv->lock);
> + watchdog_init_timeout(&a21_wdt, 30, &pdev->dev);
> + watchdog_set_nowayout(&a21_wdt, nowayout);
> + watchdog_set_drvdata(&a21_wdt, drv);
> +
> + reset = a21_wdt_get_bootstatus(drv);
> + if (reset == 2)
> + a21_wdt.bootstatus |= WDIOF_EXTERN1;
> + else if (reset == 4)
> + a21_wdt.bootstatus |= WDIOF_CARDRESET;
> + else if (reset == 5)
> + a21_wdt.bootstatus |= WDIOF_POWERUNDER;
> + else if (reset == 7)
> + a21_wdt.bootstatus |= WDIOF_EXTERN2;
> +
> +
> + ret = watchdog_register_device(&a21_wdt);
> + if (ret) {
> + dev_err(&pdev->dev, "Cannot register watchdog device\n");
> + goto err_register_wd;
> + }
> +
> + dev_set_drvdata(&pdev->dev, drv);
> +
> + return 0;
> +
> +err_register_wd:
> + mutex_destroy(&drv->lock);
> +
> + return ret;
> +}
> +
> +static int a21_wdt_remove(struct platform_device *pdev)
> +{
> + struct a21_wdt_drv *drv = dev_get_drvdata(&pdev->dev);
> +
> + dev_warn(&pdev->dev,
> + "Unregistering A21 watchdog driver, board may reboot\n");
> +
> +
> + watchdog_unregister_device(&drv->wdt);
> +
> + mutex_destroy(&drv->lock);
> +
> + return 0;
> +}
> +
> +static void a21_wdt_shutdown(struct platform_device *pdev)
> +{
> + struct a21_wdt_drv *drv = dev_get_drvdata(&pdev->dev);
> +
> + gpio_set_value(drv->gpios[GPIO_WD_ENAB], 0);
> +}
> +
> +static const struct of_device_id a21_wdt_ids[] = {
> + { .compatible = "men,a021-wdt" },
> + { },
> +};
> +
> +static struct platform_driver a21_wdt_driver = {
> + .probe = a21_wdt_probe,
> + .remove = a21_wdt_remove,
> + .shutdown = a21_wdt_shutdown,
> + .driver = {
> + .name = "a21-watchdog",
> + .of_match_table = a21_wdt_ids,
> + },
> +};
> +
> +module_platform_driver(a21_wdt_driver);
> +
> +MODULE_AUTHOR("MEN Mikro Elektronik");
> +MODULE_DESCRIPTION("MEN A21 Watchdog");
> +MODULE_LICENSE("GPL");
> +MODULE_ALIAS("platform:a21-watchdog");
> --
> 1.7.9.5
>
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