Message-ID: <93d59ca3-71e0-a717-2681-9878cbe38795@roeck-us.net>
Date:   Wed, 24 May 2017 06:45:47 -0700
From:   Guenter Roeck <linux@...ck-us.net>
To:     Keiji Hayashibara <hayashibara.keiji@...ionext.com>, wim@...ana.be
Cc:     linux-watchdog@...r.kernel.org, linux-kernel@...r.kernel.org,
        masami.hiramatsu@...aro.org, jaswinder.singh@...aro.org,
        yamada.masahiro@...ionext.com, hayashi.kunihiko@...ionext.com,
        owada.kiyoshi@...ionext.com
Subject: Re: [PATCH 1/2] watchdog: uniphier: add UniPhier watchdog driver

On 05/23/2017 11:34 PM, Keiji Hayashibara wrote:
> Add a watchdog driver for Socionext UniPhier series SoC.
> Note that the timeout value for this device must be a power
> of 2 because of the specification.
> 
> Signed-off-by: Keiji Hayashibara <hayashibara.keiji@...ionext.com>
> ---
>   .../devicetree/bindings/watchdog/uniphier-wdt.txt  |  20 ++
>   Documentation/watchdog/watchdog-parameters.txt     |   6 +
>   drivers/watchdog/Kconfig                           |  11 +
>   drivers/watchdog/Makefile                          |   1 +
>   drivers/watchdog/uniphier_wdt.c                    | 273 +++++++++++++++++++++
>   5 files changed, 311 insertions(+)
>   create mode 100644 Documentation/devicetree/bindings/watchdog/uniphier-wdt.txt
>   create mode 100644 drivers/watchdog/uniphier_wdt.c
> 
> diff --git a/Documentation/devicetree/bindings/watchdog/uniphier-wdt.txt b/Documentation/devicetree/bindings/watchdog/uniphier-wdt.txt
> new file mode 100644
> index 0000000..a59d1ba
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/watchdog/uniphier-wdt.txt
> @@ -0,0 +1,20 @@
> +UniPhier watchdog timer controller
> +
> +This UniPhier watchdog timer controller must be under sysctrl compatible node.
> +
> +Required properties:
> +- compatible: should be "socionext,uniphier-wdt"
> +
> +Example:
> +
> +	sysctrl@...40000 {
> +		compatible = "socionext,uniphier-ld11-sysctrl",
> +			     "simple-mfd", "syscon";
> +		reg = <0x61840000 0x4000>;
> +
> +		sys_wdt: watchdog {
> +			compatible = "socionext,uniphier-wdt";
> +		}
> +
> +		other nodes ...
> +	};

Bindings should be in a separate patch.

> diff --git a/Documentation/watchdog/watchdog-parameters.txt b/Documentation/watchdog/watchdog-parameters.txt > index 4f7d86d..6f9d7b4 100644
> --- a/Documentation/watchdog/watchdog-parameters.txt
> +++ b/Documentation/watchdog/watchdog-parameters.txt
> @@ -369,6 +369,12 @@ timeout: Watchdog timeout in seconds. (0<timeout<N, default=60)
>   nowayout: Watchdog cannot be stopped once started
>   	(default=kernel config parameter)
>   -------------------------------------------------
> +uniphier_wdt:
> +timeout: Watchdog timeout in power of two seconds.
> +	(1 <= timeout <= 128, default=64)
> +nowayout: Watchdog cannot be stopped once started
> +	(default=kernel config parameter)
> +-------------------------------------------------
>   w83627hf_wdt:
>   wdt_io: w83627hf/thf WDT io port (default 0x2E)
>   timeout: Watchdog timeout in seconds. 1 <= timeout <= 255, default=60.
> diff --git a/drivers/watchdog/Kconfig b/drivers/watchdog/Kconfig
> index 52a70ee..2a9d9a6 100644
> --- a/drivers/watchdog/Kconfig
> +++ b/drivers/watchdog/Kconfig
> @@ -744,6 +744,17 @@ config ZX2967_WATCHDOG
>   	  To compile this driver as a module, choose M here: the
>   	  module will be called zx2967_wdt.
>   
> +config UNIPHIER_WATCHDOG
> +	tristate "UniPhier watchdog support"
> +	depends on ARCH_UNIPHIER || COMPILE_TEST
> +	select WATCHDOG_CORE
> +	help
> +	  Say Y here to include support watchdog timer embedded
> +	  into the UniPhier system.
> +
> +	  To compile this driver as a module, choose M here: the
> +	  module will be called uniphier_wdt.
> +
>   # AVR32 Architecture
>   
>   config AT32AP700X_WDT
> diff --git a/drivers/watchdog/Makefile b/drivers/watchdog/Makefile
> index a2126e2..0928dac 100644
> --- a/drivers/watchdog/Makefile
> +++ b/drivers/watchdog/Makefile
> @@ -84,6 +84,7 @@ obj-$(CONFIG_ATLAS7_WATCHDOG) += atlas7_wdt.o
>   obj-$(CONFIG_RENESAS_WDT) += renesas_wdt.o
>   obj-$(CONFIG_ASPEED_WATCHDOG) += aspeed_wdt.o
>   obj-$(CONFIG_ZX2967_WATCHDOG) += zx2967_wdt.o
> +obj-$(CONFIG_UNIPHIER_WATCHDOG) += uniphier_wdt.o
>   
>   # AVR32 Architecture
>   obj-$(CONFIG_AT32AP700X_WDT) += at32ap700x_wdt.o
> diff --git a/drivers/watchdog/uniphier_wdt.c b/drivers/watchdog/uniphier_wdt.c
> new file mode 100644
> index 0000000..80ad2a3
> --- /dev/null
> +++ b/drivers/watchdog/uniphier_wdt.c
> @@ -0,0 +1,273 @@
> +/*
> + * Watchdog driver for the UniPhier watchdog timer
> + *
> + * (c) Copyright 2014 Panasonic Corporation
> + * (c) Copyright 2016 Socionext Inc.
> + * All rights reserved.
> + *
> + * 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.
> + *
> + * This program is distributed in the hope that it will be useful,
> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
> + * GNU General Public License for more details.
> + */
> +
> +#include <linux/delay.h>
> +#include <linux/module.h>
> +#include <linux/mfd/syscon.h>
> +#include <linux/of.h>
> +#include <linux/platform_device.h>
> +#include <linux/regmap.h>
> +#include <linux/watchdog.h>
> +
> +/* WDT timer setting register */
> +#define WDTTIMSET			0x3004
> +#define   WDTTIMSET_PERIOD_MASK		(0xf << 0)
> +#define   WDTTIMSET_PERIOD_1_SEC	(0x3 << 0)
> +#define   WDTTIMSET_PERIOD_2_SEC	(0x4 << 0)
> +#define   WDTTIMSET_PERIOD_4_SEC	(0x5 << 0)
> +#define   WDTTIMSET_PERIOD_8_SEC	(0x6 << 0)
> +#define   WDTTIMSET_PERIOD_16_SEC	(0x7 << 0)
> +#define   WDTTIMSET_PERIOD_32_SEC	(0x8 << 0)
> +#define   WDTTIMSET_PERIOD_64_SEC	(0x9 << 0)
> +#define   WDTTIMSET_PERIOD_128_SEC	(0xa << 0)
> +
> +/* WDT reset selection register */
> +#define WDTRSTSEL			0x3008
> +#define   WDTRSTSEL_RSTSEL_MASK		(0x3 << 0)
> +#define   WDTRSTSEL_RSTSEL_BOTH		(0x0 << 0)
> +#define   WDTRSTSEL_RSTSEL_IRQ_ONLY	(0x2 << 0)
> +
> +/* WDT control register */
> +#define WDTCTRL				0x300c
> +#define   WDTCTRL_STATUS		BIT(8)
> +#define   WDTCTRL_CLEAR			BIT(1)
> +#define   WDTCTRL_ENABLE		BIT(0)
> +

Should include bitops.h.

> +#define SEC_TO_WDTTIMSET_PRD(sec) \
> +		(ilog2(sec) + WDTTIMSET_PERIOD_1_SEC)
> +
> +#define WDTST_TIMEOUT			1000 /* usec */
> +
> +#define WDT_DEFAULT_TIMEOUT		64   /* Default is 64 seconds */
> +#define WDT_PERIOD_MIN			1
> +#define WDT_PERIOD_MAX			128
> +
> +static unsigned int timeout = WDT_DEFAULT_TIMEOUT;
> +static bool nowayout = WATCHDOG_NOWAYOUT;
> +
> +struct uniphier_wdt_dev {
> +	struct watchdog_device wdt_dev;
> +	struct regmap	*regmap;
> +};
> +
> +/*
> + * UniPhier Watchdog operations
> + */
> +static int uniphier_watchdog_ping(struct watchdog_device *w)
> +{
> +	struct uniphier_wdt_dev *wdev = watchdog_get_drvdata(w);
> +
> +	/* Clear counter */
> +	return regmap_write(wdev->regmap, WDTCTRL,
> +			    WDTCTRL_CLEAR | WDTCTRL_ENABLE);
> +}
> +
> +static int __uniphier_watchdog_start(struct regmap *regmap, unsigned int sec)
> +{
> +	int ret;
> +
> +	/* Setup period */
> +	ret = regmap_write(regmap, WDTTIMSET,
> +			   SEC_TO_WDTTIMSET_PRD(sec));
> +	if (ret)
> +		return ret;
> +
> +	/* Enable and clear watchdog */
> +	return regmap_write(regmap, WDTCTRL, WDTCTRL_ENABLE | WDTCTRL_CLEAR);
> +}
> +
> +static int __uniphier_watchdog_stop(struct regmap *regmap)
> +{
> +	/* Disable and stop watchdog */
> +	return regmap_write_bits(regmap, WDTCTRL, WDTCTRL_ENABLE, 0);
> +}
> +
> +static int __uniphier_watchdog_restart(struct regmap *regmap, unsigned int sec)
> +{
> +	unsigned int val;
> +	int ret;
> +
> +	ret = __uniphier_watchdog_stop(regmap);
> +	if (ret)
> +		return ret;
> +
> +	ret = regmap_read_poll_timeout(regmap, WDTCTRL, val,
> +				       !(val & WDTCTRL_STATUS),
> +				       0, WDTST_TIMEOUT);
> +	if (ret)
> +		return ret;
> +
> +	return __uniphier_watchdog_start(regmap, sec);
> +}
> +
> +static int uniphier_watchdog_start(struct watchdog_device *w)
> +{
> +	struct uniphier_wdt_dev *wdev = watchdog_get_drvdata(w);
> +	unsigned int tmp_timeout;
> +
> +	tmp_timeout = roundup_pow_of_two(w->timeout);
> +
> +	return __uniphier_watchdog_start(wdev->regmap, tmp_timeout);
> +}
> +
> +static int uniphier_watchdog_stop(struct watchdog_device *w)
> +{
> +	struct uniphier_wdt_dev *wdev = watchdog_get_drvdata(w);
> +
> +	return __uniphier_watchdog_stop(wdev->regmap);
> +}
> +
> +static int uniphier_watchdog_set_timeout(struct watchdog_device *w,
> +					 unsigned int t)
> +{
> +	struct uniphier_wdt_dev *wdev = watchdog_get_drvdata(w);
> +	unsigned int tmp_timeout;
> +	int ret;
> +
> +	tmp_timeout = roundup_pow_of_two(t);
> +	if (tmp_timeout == w->timeout)
> +		return 0;
> +
> +	if (watchdog_active(w)) {
> +		ret = __uniphier_watchdog_restart(wdev->regmap, tmp_timeout);
> +		if (ret)
> +			return ret;
> +	}
> +
> +	w->timeout = tmp_timeout;
> +
> +	return 0;
> +}
> +
> +/*
> + * Kernel Interfaces
> + */
> +static const struct watchdog_info uniphier_wdt_info = {
> +	.identity	= "uniphier-wdt",
> +	.options	= WDIOF_SETTIMEOUT |
> +			  WDIOF_KEEPALIVEPING |
> +			  WDIOF_MAGICCLOSE |
> +			  WDIOF_OVERHEAT,
> +};
> +
> +static const struct watchdog_ops uniphier_wdt_ops = {
> +	.owner		= THIS_MODULE,
> +	.start		= uniphier_watchdog_start,
> +	.stop		= uniphier_watchdog_stop,
> +	.ping		= uniphier_watchdog_ping,
> +	.set_timeout	= uniphier_watchdog_set_timeout,
> +	.restart	= NULL,

What is this about ? It is unnecessary to set a static variable to NULL.

> +};
> +
> +static int uniphier_wdt_probe(struct platform_device *pdev)
> +{
> +	struct device *dev = &pdev->dev;
> +	struct uniphier_wdt_dev *wdev;
> +	struct regmap *regmap;
> +	struct device_node *parent;
> +	int ret;
> +
> +	wdev = devm_kzalloc(dev, sizeof(*wdev), GFP_KERNEL);
> +	if (!wdev)
> +		return -ENOMEM;
> +
> +	platform_set_drvdata(pdev, wdev);
> +
> +	parent = of_get_parent(dev->of_node); /* parent should be syscon node */
> +	regmap = syscon_node_to_regmap(parent);
> +	of_node_put(parent);
> +	if (IS_ERR(regmap))
> +		return PTR_ERR(regmap);
> +
> +	wdev->regmap = regmap;
> +	wdev->wdt_dev.info = &uniphier_wdt_info;
> +	wdev->wdt_dev.ops = &uniphier_wdt_ops;
> +	wdev->wdt_dev.timeout = WDT_DEFAULT_TIMEOUT;
> +	wdev->wdt_dev.max_timeout = WDT_PERIOD_MAX;
> +	wdev->wdt_dev.min_timeout = WDT_PERIOD_MIN;
> +	wdev->wdt_dev.parent = dev;
> +
> +	watchdog_init_timeout(&wdev->wdt_dev, timeout, dev);
> +	watchdog_set_nowayout(&wdev->wdt_dev, nowayout);
> +	watchdog_set_restart_priority(&wdev->wdt_dev, 128);

This does not make sense without a restart handler function.

> +
> +	watchdog_set_drvdata(&wdev->wdt_dev, wdev);
> +
> +	uniphier_watchdog_stop(&wdev->wdt_dev);
> +	ret = regmap_write(wdev->regmap, WDTRSTSEL, WDTRSTSEL_RSTSEL_BOTH);
> +	if (ret)
> +		return ret;
> +
> +	ret = watchdog_register_device(&wdev->wdt_dev);

You can use devm_watchdog_register_device().

> +	if (ret)
> +		return ret;
> +
> +	dev_info(dev, "watchdog driver (timeout=%d sec, nowayout=%d)\n",
> +		 wdev->wdt_dev.timeout, nowayout);
> +
> +	return 0;
> +}
> +
> +static void uniphier_wdt_shutdown(struct platform_device *pdev)
> +{
> +	struct uniphier_wdt_dev *wdev = platform_get_drvdata(pdev);
> +
> +	if (watchdog_active(&wdev->wdt_dev))
> +		uniphier_watchdog_stop(&wdev->wdt_dev);

Can you use WDOG_STOP_ON_REBOOT instead ?

> +}
> +
> +static int uniphier_wdt_remove(struct platform_device *pdev)
> +{
> +	struct uniphier_wdt_dev *wdev = platform_get_drvdata(pdev);
> +
> +	watchdog_unregister_device(&wdev->wdt_dev);
> +
> +	return 0;
> +}
> +
> +static const struct of_device_id uniphier_wdt_dt_ids[] = {
> +	{ .compatible = "socionext,uniphier-wdt" },
> +	{ /* sentinel */ }
> +};
> +MODULE_DEVICE_TABLE(of, uniphier_wdt_dt_ids);
> +
> +static struct platform_driver uniphier_wdt_driver = {
> +	.probe		= uniphier_wdt_probe,
> +	.remove		= uniphier_wdt_remove,
> +	.shutdown	= uniphier_wdt_shutdown,
> +	.driver		= {
> +		.name		= "uniphier-wdt",
> +		.of_match_table	= uniphier_wdt_dt_ids,
> +	},
> +};
> +
> +module_platform_driver(uniphier_wdt_driver);
> +
> +module_param(timeout, uint, 0000);
> +MODULE_PARM_DESC(timeout,
> +	"Watchdog timeout seconds in power of 2. (0 < timeout < 128, default="
> +				__MODULE_STRING(WDT_DEFAULT_TIMEOUT) ")");
> +
> +module_param(nowayout, bool, 0000);
> +MODULE_PARM_DESC(nowayout,
> +	"Watchdog cannot be stopped once started (default="
> +				__MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
> +
> +MODULE_AUTHOR("Socionext Inc.");
> +MODULE_DESCRIPTION("UniPhier Watchdog Device Driver");
> +MODULE_LICENSE("GPL v2");
> 

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