Re: [PATCH v3] watchdog: atlas7: add watchdog driver of CSRatlas7

[Guenter Roeck <linux@roeck-us.net>]

On 11/30/2015 11:43 PM, Barry Song wrote:
> From: Guo Zeng <Guo.Zeng@csr.com>
>
> This patch adds watchdog driver for CSRatlas7 platform.
> On CSRatlas7, the 6th timer can act as a watchdog timer
> when the Watchdog mode is enabled.
>
> Cc: Guenter Roeck <linux@roeck-us.net>
> Signed-off-by: Guo Zeng <Guo.Zeng@csr.com>
> Signed-off-by: William Wang <William.Wang@csr.com>
> Signed-off-by: Barry Song <Baohua.Song@csr.com>

Are those people all in the sign-off path, or just somehow involved
in writing the code ?

> ---
>   -v3: fix issues according to Guenter's comments
>    1. rename updatetimeout to ping
>    2. drop redundant calling ping in set_timeout
>    3. fix the error handler in probe
>    4. move to __maybe_unused for suspend/resume entries
>    5. fix the min and max timeout
>    6. clean up clear ugly codes for timeout set
>
>   drivers/watchdog/Kconfig      |  10 ++
>   drivers/watchdog/Makefile     |   1 +
>   drivers/watchdog/atlas7_wdt.c | 249 ++++++++++++++++++++++++++++++++++++++++++
>   3 files changed, 260 insertions(+)
>   create mode 100644 drivers/watchdog/atlas7_wdt.c
>
> diff --git a/drivers/watchdog/Kconfig b/drivers/watchdog/Kconfig
> index 1c427be..52b308f 100644
> --- a/drivers/watchdog/Kconfig
> +++ b/drivers/watchdog/Kconfig
> @@ -578,6 +578,16 @@ config LPC18XX_WATCHDOG
>   	  To compile this driver as a module, choose M here: the
>   	  module will be called lpc18xx_wdt.
>
> +config ATLAS7_WATCHDOG
> +	tristate "CSRatlas7 watchdog"
> +	depends on ARCH_ATLAS7
> +	help
> +	  Say Y here to include Watchdog timer support for the watchdog
> +	  existing on the CSRatlas7 series platforms.
> +
> +	  To compile this driver as a module, choose M here: the
> +	  module will be called atlas7_wdt.
> +
>   # AVR32 Architecture
>
>   config AT32AP700X_WDT
> diff --git a/drivers/watchdog/Makefile b/drivers/watchdog/Makefile
> index 53d4827..e2bc52c 100644
> --- a/drivers/watchdog/Makefile
> +++ b/drivers/watchdog/Makefile
> @@ -69,6 +69,7 @@ obj-$(CONFIG_MEDIATEK_WATCHDOG) += mtk_wdt.o
>   obj-$(CONFIG_DIGICOLOR_WATCHDOG) += digicolor_wdt.o
>   obj-$(CONFIG_LPC18XX_WATCHDOG) += lpc18xx_wdt.o
>   obj-$(CONFIG_BCM7038_WDT) += bcm7038_wdt.o
> +obj-$(CONFIG_ATLAS7_WATCHDOG) += atlas7_wdt.o
>
>   # AVR32 Architecture
>   obj-$(CONFIG_AT32AP700X_WDT) += at32ap700x_wdt.o
> diff --git a/drivers/watchdog/atlas7_wdt.c b/drivers/watchdog/atlas7_wdt.c
> new file mode 100644
> index 0000000..4f191fe
> --- /dev/null
> +++ b/drivers/watchdog/atlas7_wdt.c
> @@ -0,0 +1,249 @@
> +/*
> + * Watchdog driver for CSRatlas7
> + *
> + * Copyright (c) 2015 Cambridge Silicon Radio Limited, a CSR plc group company.
> + *
> + * Licensed under GPLv2 or later.
> + */
> +
> +#include <linux/module.h>
> +#include <linux/watchdog.h>
> +#include <linux/platform_device.h>
> +#include <linux/moduleparam.h>
> +#include <linux/of.h>
> +#include <linux/io.h>
> +#include <linux/uaccess.h>

Not required.

> +#include <linux/clk.h>
> +
Please order include files alphabetically.

> +#define ATLAS7_TIMER_WDT_INDEX		5
> +#define ATLAS7_WDT_DEFAULT_TIMEOUT	20		/* 20 secs */
> +
> +#define ATLAS7_WDT_CNT_CTRL	0
> +#define ATLAS7_WDT_CNT_MATCH	0x18
> +#define ATLAS7_WDT_CNT		0x48

Wondering - below you always add 4 * ATLAS7_TIMER_WDT_INDEX
to the WDT_CNT_CTRL, WDT_CNT_MATCH, and WDT_CNT registers.
Wouldn't it be easier to specify the final register offsets directly ?

#define ATLAS7_WDT_CNT_CTRL	(0 + 4 * ATLAS7_TIMER_WDT_INDEX)

or even

#define ATLAS7_WDT_CNT_CTRL	0x14

The long expressions below just make the code more difficult to read.

> +#define ATLAS7_WDT_CNT_EN	(BIT(0) | BIT(1))
> +#define ATLAS7_WDT_EN		0x64
> +
> +static unsigned int timeout = ATLAS7_WDT_DEFAULT_TIMEOUT;

This will cause a devicetree based initialization to be ignored.
It would be better to set this to 0 and initialize .timeout with
ATLAS7_WDT_DEFAULT_TIMEOUT prior to calling watchdog_init_timeout().

> +static bool nowayout = WATCHDOG_NOWAYOUT;
> +
> +module_param(timeout, uint, 0);
> +module_param(nowayout, bool, 0);
> +
> +MODULE_PARM_DESC(timeout, "Default watchdog timeout (in seconds)");
> +MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="
> +			__MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
> +
> +struct atlas7_wdog {
> +	struct device *dev;
> +	void __iomem *base;
> +	unsigned long tick_rate;
> +	struct clk *clk;
> +};
> +
> +static unsigned int atlas7_wdt_gettimeleft(struct watchdog_device *wdd)
> +{
> +	struct atlas7_wdog *wdt = watchdog_get_drvdata(wdd);
> +	u32 counter, match, delta;
> +
> +	counter = readl(wdt->base + ATLAS7_WDT_CNT +
> +		4 * ATLAS7_TIMER_WDT_INDEX);
> +	match = readl(wdt->base + ATLAS7_WDT_CNT_MATCH +
> +			4 * ATLAS7_TIMER_WDT_INDEX);

In general, continuation lines should be aligned with '('.

On the other side, macros such as

#define WDT_CNT_REG(wdt)	((wdt)->base + ATLAS7_WDT_CNT + 4 * ATLAS7_TIMER_WDT_INDEX)
#define WDT_CNT_MATCH_REG(wdt)	((wdt)->base + ATLAS7_WDT_CNT_MATCH + 4 * ATLAS7_TIMER_WDT_INDEX)
#define WDT_CNT_CTRL_REG(wdt)	((wdt)->base + ATLAS7_WDT_CNT_CTRL + 4 * ATLAS7_TIMER_WDT_INDEX)

might be quite useful to avoid the repeated use of long expressions.
Or at least simplify the register definitions as suggested above.

> +	delta = match - counter;
> +
> +	return  delta / wdt->tick_rate;
> +}
> +
> +static int atlas7_wdt_ping(struct watchdog_device *wdd)
> +{
> +	struct atlas7_wdog *wdt = watchdog_get_drvdata(wdd);
> +	u32 counter, match, delta;
> +
> +	counter = readl(wdt->base + ATLAS7_WDT_CNT +
> +			4 * ATLAS7_TIMER_WDT_INDEX);
> +	delta = wdd->timeout * wdt->tick_rate;
> +	match = counter + delta;
> +
> +	writel(match, wdt->base + ATLAS7_WDT_CNT_MATCH +
> +		4 * ATLAS7_TIMER_WDT_INDEX);
> +
> +	return 0;
> +}
> +
> +static int atlas7_wdt_enable(struct watchdog_device *wdd)
> +{
> +	struct atlas7_wdog *wdt = watchdog_get_drvdata(wdd);
> +	void __iomem *ctrl_reg = wdt->base + ATLAS7_WDT_CNT_CTRL +
> +		4 * ATLAS7_TIMER_WDT_INDEX;
> +
> +	atlas7_wdt_ping(wdd);
> +
> +	writel(readl(ctrl_reg) | ATLAS7_WDT_CNT_EN, ctrl_reg);
> +	writel(1, wdt->base + ATLAS7_WDT_EN);
> +
> +	return 0;
> +}
> +
> +static int atlas7_wdt_disable(struct watchdog_device *wdd)
> +{
> +	struct atlas7_wdog *wdt = watchdog_get_drvdata(wdd);
> +	void __iomem *ctrl_reg = wdt->base + ATLAS7_WDT_CNT_CTRL +
> +		4 * ATLAS7_TIMER_WDT_INDEX;
> +
> +	writel(0, wdt->base + ATLAS7_WDT_EN);
> +	writel(readl(ctrl_reg) & ~ATLAS7_WDT_CNT_EN, ctrl_reg);
> +
> +	return 0;
> +}
> +
> +static int atlas7_wdt_settimeout(struct watchdog_device *wdd, unsigned int to)
> +{
> +	wdd->timeout = to;
> +
> +	return 0;
> +}
> +
> +#define OPTIONS (WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE)
> +
> +static const struct watchdog_info atlas7_wdt_ident = {
> +	.options          =     OPTIONS,
> +	.firmware_version =	0,
> +	.identity         =	"atlas7 Watchdog",

The tab after '=' is really unnecessary. I would suggest to replace it with a space.

> +};
> +
> +static struct watchdog_ops atlas7_wdt_ops = {
> +	.owner = THIS_MODULE,
> +	.start = atlas7_wdt_enable,
> +	.stop = atlas7_wdt_disable,
> +	.get_timeleft = atlas7_wdt_gettimeleft,
> +	.ping = atlas7_wdt_ping,
> +	.set_timeout = atlas7_wdt_settimeout,
> +};
> +
> +static struct watchdog_device atlas7_wdd = {
> +	.info = &atlas7_wdt_ident,
> +	.ops = &atlas7_wdt_ops,
> +	.timeout = ATLAS7_WDT_DEFAULT_TIMEOUT,
> +};
> +
> +static const struct of_device_id atlas7_wdt_ids[] = {
> +	{ .compatible = "sirf,atlas7-tick"},
> +	{}
> +};
> +
> +static int atlas7_wdt_probe(struct platform_device *pdev)
> +{
> +	struct device_node *np = pdev->dev.of_node;
> +	struct atlas7_wdog *wdt;
> +	struct resource *res;
> +	struct clk *clk;
> +	int ret;
> +
> +	wdt = devm_kzalloc(&pdev->dev, sizeof(*wdt), GFP_KERNEL);
> +	if (!wdt)
> +		return -ENOMEM;
> +	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> +	wdt->base = devm_ioremap_resource(&pdev->dev, res);
> +	if (IS_ERR(wdt->base))
> +		return PTR_ERR(wdt->base);
> +
> +	clk = of_clk_get(np, 0);
> +	if (IS_ERR(clk)) {
> +		ret = PTR_ERR(clk);
> +		goto err;

You can just return PTR_ERR(clk) here.
The "err:" label, just to return, is unnecessary.


> +	}
> +	ret = clk_prepare_enable(clk);
> +	if (ret) {
> +		pr_err("wdt clk enable failed\n");
> +		goto err1;

wdt->clk is not yet set here, meaning the clk_put() below won't work.

> +	}
> +
> +	/* disable watchdog hardware */
> +	writel(0, wdt->base + ATLAS7_WDT_CNT_CTRL +
> +			4 * ATLAS7_TIMER_WDT_INDEX);
> +
> +	wdt->tick_rate = clk_get_rate(clk);
> +	wdt->clk = clk;
> +	atlas7_wdd.min_timeout = 1;
> +	atlas7_wdd.max_timeout = UINT_MAX / wdt->tick_rate;
> +
> +	watchdog_init_timeout(&atlas7_wdd, timeout, &pdev->dev);
> +	watchdog_set_nowayout(&atlas7_wdd, nowayout);
> +
> +	watchdog_set_drvdata(&atlas7_wdd, wdt);
> +	platform_set_drvdata(pdev, &atlas7_wdd);
> +
> +	ret = watchdog_register_device(&atlas7_wdd);
> +	if (ret)
> +		goto err2;
> +
> +	return 0;
> +
> +err2:
> +	clk_disable_unprepare(wdt->clk);
> +err1:
> +	clk_put(wdt->clk);
> +err:
> +	return ret;
> +}
> +
> +static void atlas7_wdt_shutdown(struct platform_device *pdev)
> +{
> +	struct watchdog_device *wdd = platform_get_drvdata(pdev);
> +	struct atlas7_wdog *wdt = watchdog_get_drvdata(wdd);
> +
> +	atlas7_wdt_disable(wdd);
> +	clk_disable_unprepare(wdt->clk);
> +}
> +
> +static int atlas7_wdt_remove(struct platform_device *pdev)
> +{
> +	struct watchdog_device *wdd = platform_get_drvdata(pdev);
> +	struct atlas7_wdog *wdt = watchdog_get_drvdata(wdd);
> +
> +	atlas7_wdt_shutdown(pdev);
> +	clk_put(wdt->clk);
> +	return 0;
> +}
> +
> +static int __maybe_unused atlas7_wdt_suspend(struct device *dev)
> +{
> +	return 0;

Is it not necessary to stop the watchdog ? If the watchdog is disabled
elsewhere, a similar comment to the one below would help.

> +}
> +
> +static int __maybe_unused atlas7_wdt_resume(struct device *dev)
> +{
> +	struct watchdog_device *wdd = dev_get_drvdata(dev);
> +
> +	/*
> +	 * NOTE: Since timer controller registers settings are saved
> +	 * and restored back by the timer-atlas7.c, so we need not
> +	 * update WD settings except refreshing timeout.
> +	 */
> +	atlas7_wdt_ping(wdd);
> +
> +	return 0;
> +}
> +
> +static SIMPLE_DEV_PM_OPS(atlas7_wdt_pm_ops,
> +		atlas7_wdt_suspend, atlas7_wdt_resume);
> +
> +MODULE_DEVICE_TABLE(of, atlas7_wdt_ids);
> +
> +static struct platform_driver atlas7_wdt_driver = {
> +	.driver = {
> +		.name = "atlas7-wdt",
> +		.pm = &atlas7_wdt_pm_ops,
> +		.of_match_table	= atlas7_wdt_ids,
> +	},
> +	.probe = atlas7_wdt_probe,
> +	.remove = atlas7_wdt_remove,
> +	.shutdown = atlas7_wdt_shutdown,
> +};
> +module_platform_driver(atlas7_wdt_driver);
> +
> +MODULE_DESCRIPTION("CSRatlas7 watchdog driver");
> +MODULE_AUTHOR("Guo Zeng <Guo.Zeng@csr.com>");
> +MODULE_LICENSE("GPL v2");

This contradicts "GPL v2 or later" in the comments at the beginning of the file.

> +MODULE_ALIAS("platform:atlas7-wdt");
>