Date:   Mon, 5 Dec 2016 16:05:01 -0800
From:   Guenter Roeck <linux@...ck-us.net>
To:     Yang Ling <gnaygnil@...il.com>
Cc:     wim@...ana.be, keguang.zhang@...il.com,
        linux-kernel@...r.kernel.org, linux-watchdog@...r.kernel.org,
        linux-mips@...ux-mips.org
Subject: Re: [PATCH v2.4 2/3] watchdog: loongson1: Add Loongson1 SoC watchdog
 driver

On Mon, Dec 05, 2016 at 11:00:53PM +0800, Yang Ling wrote:
> Add watchdog timer specific driver for Loongson1 SoC.
> 
> Signed-off-by: Yang Ling <gnaygnil@...il.com>
> 
> ---
> V2.4:
>   Set DEFAULT_HEARTBEAT to 0.
> V2.3:
>   Set DEFAULT_HEARTBEAT value to ls1x_wdt->timeout.
> V2.2:
>   Remove the wide character.
>   Check the return value for clk_get_rate().
> V2.1 from Kelvin Cheung:
>   Use max_hw_heartbeat_ms instead of max_timeout.
> V2.0:
>   Increase the value of the default heartbeat.
>   Modify the setup process for register.
>   Order include files and Makefile alphabetically.
> V1.1:
>   Add a little debugging information.
> ---
>  drivers/watchdog/Kconfig         |   7 ++
>  drivers/watchdog/Makefile        |   1 +
>  drivers/watchdog/loongson1_wdt.c | 170 +++++++++++++++++++++++++++++++++++++++
>  3 files changed, 178 insertions(+)
>  create mode 100644 drivers/watchdog/loongson1_wdt.c
> 
> diff --git a/drivers/watchdog/Kconfig b/drivers/watchdog/Kconfig
> index fdd3228..c5b9c6e 100644
> --- a/drivers/watchdog/Kconfig
> +++ b/drivers/watchdog/Kconfig
> @@ -1513,6 +1513,13 @@ config LANTIQ_WDT
>  	help
>  	  Hardware driver for the Lantiq SoC Watchdog Timer.
>  
> +config LOONGSON1_WDT
> +	tristate "Loongson1 SoC hardware watchdog"
> +	depends on MACH_LOONGSON32
> +	select WATCHDOG_CORE
> +	help
> +	  Hardware driver for the Loongson1 SoC Watchdog Timer.
> +
>  config RALINK_WDT
>  	tristate "Ralink SoC watchdog"
>  	select WATCHDOG_CORE
> diff --git a/drivers/watchdog/Makefile b/drivers/watchdog/Makefile
> index caa9f4a..0c3d35e 100644
> --- a/drivers/watchdog/Makefile
> +++ b/drivers/watchdog/Makefile
> @@ -163,6 +163,7 @@ obj-$(CONFIG_TXX9_WDT) += txx9wdt.o
>  obj-$(CONFIG_OCTEON_WDT) += octeon-wdt.o
>  octeon-wdt-y := octeon-wdt-main.o octeon-wdt-nmi.o
>  obj-$(CONFIG_LANTIQ_WDT) += lantiq_wdt.o
> +obj-$(CONFIG_LOONGSON1_WDT) += loongson1_wdt.o
>  obj-$(CONFIG_RALINK_WDT) += rt2880_wdt.o
>  obj-$(CONFIG_IMGPDC_WDT) += imgpdc_wdt.o
>  obj-$(CONFIG_MT7621_WDT) += mt7621_wdt.o
> diff --git a/drivers/watchdog/loongson1_wdt.c b/drivers/watchdog/loongson1_wdt.c
> new file mode 100644
> index 0000000..1c75bda
> --- /dev/null
> +++ b/drivers/watchdog/loongson1_wdt.c
> @@ -0,0 +1,170 @@
> +/*
> + * Copyright (c) 2016 Yang Ling <gnaygnil@...il.com>
> + *
> + * 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/clk.h>
> +#include <linux/module.h>
> +#include <linux/platform_device.h>
> +#include <linux/watchdog.h>
> +#include <loongson1.h>
> +
> +#define DEFAULT_HEARTBEAT	0
> +

This is not what I said or meant, and quite pointless.

> +static bool nowayout = WATCHDOG_NOWAYOUT;
> +module_param(nowayout, bool, 0444);
> +
> +static unsigned int heartbeat = DEFAULT_HEARTBEAT;

What I said and meant was that this variable should be initialized with 0,
ie just be declared as

static unsigned int heartbeat;

Guenter

> +module_param(heartbeat, uint, 0444);
> +
> +struct ls1x_wdt_drvdata {
> +	void __iomem *base;
> +	struct clk *clk;
> +	unsigned long clk_rate;
> +	struct watchdog_device wdt;
> +};
> +
> +static int ls1x_wdt_ping(struct watchdog_device *wdt_dev)
> +{
> +	struct ls1x_wdt_drvdata *drvdata = watchdog_get_drvdata(wdt_dev);
> +
> +	writel(0x1, drvdata->base + WDT_SET);
> +
> +	return 0;
> +}
> +
> +static int ls1x_wdt_set_timeout(struct watchdog_device *wdt_dev,
> +				unsigned int timeout)
> +{
> +	struct ls1x_wdt_drvdata *drvdata = watchdog_get_drvdata(wdt_dev);
> +	unsigned int max_hw_heartbeat = wdt_dev->max_hw_heartbeat_ms / 1000;
> +	unsigned int counts;
> +
> +	wdt_dev->timeout = timeout;
> +
> +	counts = drvdata->clk_rate * min(timeout, max_hw_heartbeat);
> +	writel(counts, drvdata->base + WDT_TIMER);
> +
> +	return 0;
> +}
> +
> +static int ls1x_wdt_start(struct watchdog_device *wdt_dev)
> +{
> +	struct ls1x_wdt_drvdata *drvdata = watchdog_get_drvdata(wdt_dev);
> +
> +	writel(0x1, drvdata->base + WDT_EN);
> +
> +	return 0;
> +}
> +
> +static int ls1x_wdt_stop(struct watchdog_device *wdt_dev)
> +{
> +	struct ls1x_wdt_drvdata *drvdata = watchdog_get_drvdata(wdt_dev);
> +
> +	writel(0x0, drvdata->base + WDT_EN);
> +
> +	return 0;
> +}
> +
> +static const struct watchdog_info ls1x_wdt_info = {
> +	.options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE,
> +	.identity = "Loongson1 Watchdog",
> +};
> +
> +static const struct watchdog_ops ls1x_wdt_ops = {
> +	.owner = THIS_MODULE,
> +	.start = ls1x_wdt_start,
> +	.stop = ls1x_wdt_stop,
> +	.ping = ls1x_wdt_ping,
> +	.set_timeout = ls1x_wdt_set_timeout,
> +};
> +
> +static int ls1x_wdt_probe(struct platform_device *pdev)
> +{
> +	struct ls1x_wdt_drvdata *drvdata;
> +	struct watchdog_device *ls1x_wdt;
> +	unsigned long clk_rate;
> +	struct resource *res;
> +	int err;
> +
> +	drvdata = devm_kzalloc(&pdev->dev, sizeof(*drvdata), GFP_KERNEL);
> +	if (!drvdata)
> +		return -ENOMEM;
> +
> +	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> +	drvdata->base = devm_ioremap_resource(&pdev->dev, res);
> +	if (IS_ERR(drvdata->base))
> +		return PTR_ERR(drvdata->base);
> +
> +	drvdata->clk = devm_clk_get(&pdev->dev, pdev->name);
> +	if (IS_ERR(drvdata->clk))
> +		return PTR_ERR(drvdata->clk);
> +
> +	err = clk_prepare_enable(drvdata->clk);
> +	if (err) {
> +		dev_err(&pdev->dev, "clk enable failed\n");
> +		return err;
> +	}
> +
> +	clk_rate = clk_get_rate(drvdata->clk);
> +	if (!clk_rate) {
> +		err = -EINVAL;
> +		goto err0;
> +	}
> +	drvdata->clk_rate = clk_rate;
> +
> +	ls1x_wdt = &drvdata->wdt;
> +	ls1x_wdt->info = &ls1x_wdt_info;
> +	ls1x_wdt->ops = &ls1x_wdt_ops;
> +	ls1x_wdt->timeout = DEFAULT_HEARTBEAT;
> +	ls1x_wdt->min_timeout = 1;
> +	ls1x_wdt->max_hw_heartbeat_ms = U32_MAX / clk_rate * 1000;
> +	ls1x_wdt->parent = &pdev->dev;
> +
> +	watchdog_init_timeout(ls1x_wdt, heartbeat, &pdev->dev);
> +	watchdog_set_nowayout(ls1x_wdt, nowayout);
> +	watchdog_set_drvdata(ls1x_wdt, drvdata);
> +
> +	err = watchdog_register_device(&drvdata->wdt);
> +	if (err) {
> +		dev_err(&pdev->dev, "failed to register watchdog device\n");
> +		goto err0;
> +	}
> +
> +	platform_set_drvdata(pdev, drvdata);
> +
> +	dev_info(&pdev->dev, "Loongson1 Watchdog driver registered\n");
> +
> +	return 0;
> +err0:
> +	clk_disable_unprepare(drvdata->clk);
> +	return err;
> +}
> +
> +static int ls1x_wdt_remove(struct platform_device *pdev)
> +{
> +	struct ls1x_wdt_drvdata *drvdata = platform_get_drvdata(pdev);
> +
> +	watchdog_unregister_device(&drvdata->wdt);
> +	clk_disable_unprepare(drvdata->clk);
> +
> +	return 0;
> +}
> +
> +static struct platform_driver ls1x_wdt_driver = {
> +	.probe = ls1x_wdt_probe,
> +	.remove = ls1x_wdt_remove,
> +	.driver = {
> +		.name = "ls1x-wdt",
> +	},
> +};
> +
> +module_platform_driver(ls1x_wdt_driver);
> +
> +MODULE_AUTHOR("Yang Ling <gnaygnil@...il.com>");
> +MODULE_DESCRIPTION("Loongson1 Watchdog Driver");
> +MODULE_LICENSE("GPL");
> -- 
> 1.9.1
> 

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