Message-ID: <528AF200.5070204@roeck-us.net>
Date:	Mon, 18 Nov 2013 21:07:12 -0800
From:	Guenter Roeck <linux@...ck-us.net>
To:	Markus Mayer <markus.mayer@...aro.org>,
	Wim Van Sebroeck <wim@...ana.be>,
	Christian Daudt <bcm@...thebug.org>
CC:	Linaro Patches <patches@...aro.org>,
	Matt Porter <matt.porter@...aro.org>,
	One Thousand Gnomes <gnomes@...rguk.ukuu.org.uk>,
	Linux Watchdog List <linux-watchdog@...r.kernel.org>,
	ARM Kernel List <linux-arm-kernel@...ts.infradead.org>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v3 1/2] watchdog: bcm281xx: Watchdog Driver

On 11/18/2013 05:24 PM, Markus Mayer wrote:
> This commit adds support for the watchdog timer used on the BCM281xx
> family of SoCs.
>
> Signed-off-by: Markus Mayer <markus.mayer@...aro.org>
> Reviewed-by: Matt Porter <matt.porter@...aro.org>
> ---
>   drivers/watchdog/Kconfig        |   22 +++
>   drivers/watchdog/Makefile       |    1 +
>   drivers/watchdog/bcm_kona_wdt.c |  366 +++++++++++++++++++++++++++++++++++++++
>   3 files changed, 389 insertions(+)
>   create mode 100644 drivers/watchdog/bcm_kona_wdt.c
>
> diff --git a/drivers/watchdog/Kconfig b/drivers/watchdog/Kconfig
> index d1d53f3..fe8bd21 100644
> --- a/drivers/watchdog/Kconfig
> +++ b/drivers/watchdog/Kconfig
> @@ -1121,6 +1121,28 @@ config BCM2835_WDT
>   	  To compile this driver as a loadable module, choose M here.
>   	  The module will be called bcm2835_wdt.
>
> +config BCM_KONA_WDT
> +	tristate "BCM Kona Watchdog"
> +	depends on ARCH_BCM
> +	select WATCHDOG_CORE
> +	help
> +	  Support for the watchdog timer on the following Broadcom BCM281xx
> +	  family, which includes BCM11130, BCM11140, BCM11351, BCM28145 and
> +	  BCM28155 variants.
> +
> +	  Say 'Y' or 'M' here to enable the driver. The module will be called
> +	  bcm_kona_wdt.
> +
> +config BCM_KONA_WDT_DEBUG
> +	bool "DEBUGFS support for BCM Kona Watchdog"
> +	depends on BCM_KONA_WDT
> +	help
> +	  If enabled, adds /sys/kernel/debug/bcm-kona-wdt/info which provides
> +	  access to the driver's internal data structures as well as watchdog
> +	  timer hardware registres.
> +
> +	  If in doubt, say 'N'.
> +
>   config LANTIQ_WDT
>   	tristate "Lantiq SoC watchdog"
>   	depends on LANTIQ
> diff --git a/drivers/watchdog/Makefile b/drivers/watchdog/Makefile
> index 6c5bb27..7c860ca 100644
> --- a/drivers/watchdog/Makefile
> +++ b/drivers/watchdog/Makefile
> @@ -55,6 +55,7 @@ obj-$(CONFIG_IMX2_WDT) += imx2_wdt.o
>   obj-$(CONFIG_UX500_WATCHDOG) += ux500_wdt.o
>   obj-$(CONFIG_RETU_WATCHDOG) += retu_wdt.o
>   obj-$(CONFIG_BCM2835_WDT) += bcm2835_wdt.o
> +obj-$(CONFIG_BCM_KONA_WDT) += bcm_kona_wdt.o
>
>   # AVR32 Architecture
>   obj-$(CONFIG_AT32AP700X_WDT) += at32ap700x_wdt.o
> diff --git a/drivers/watchdog/bcm_kona_wdt.c b/drivers/watchdog/bcm_kona_wdt.c
> new file mode 100644
> index 0000000..f43687f
> --- /dev/null
> +++ b/drivers/watchdog/bcm_kona_wdt.c
> @@ -0,0 +1,366 @@
> +/*
> + * Copyright (C) 2013 Broadcom Corporation
> + *
> + * 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 version 2.
> + *
> + * This program is distributed "as is" WITHOUT ANY WARRANTY of any
> + * kind, whether express or implied; without even the implied warranty
> + * of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
> + * GNU General Public License for more details.
> + */
> +
> +#include <linux/debugfs.h>
> +#include <linux/delay.h>
> +#include <linux/err.h>
> +#include <linux/io.h>
> +#include <linux/miscdevice.h>

This include should no longer be needed.

Otherwise,

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


> +#include <linux/module.h>
> +#include <linux/of_address.h>
> +#include <linux/platform_device.h>
> +#include <linux/watchdog.h>
> +
> +#define SECWDOG_CTRL_REG		0x00000000
> +#define SECWDOG_COUNT_REG		0x00000004
> +
> +#define SECWDOG_RESERVED_MASK		0x1dffffff
> +#define SECWDOG_WD_LOAD_FLAG		0x10000000
> +#define SECWDOG_EN_MASK			0x08000000
> +#define SECWDOG_SRSTEN_MASK		0x04000000
> +#define SECWDOG_RES_MASK		0x00f00000
> +#define SECWDOG_COUNT_MASK		0x000fffff
> +
> +#define SECWDOG_MAX_COUNT		SECWDOG_COUNT_MASK
> +#define SECWDOG_CLKS_SHIFT		20
> +#define SECWDOG_MAX_RES			15
> +#define SECWDOG_DEFAULT_RESOLUTION	4
> +#define SECWDOG_MAX_TRY			1000
> +
> +#define SECS_TO_TICKS(x, w)		((x) << (w)->resolution)
> +#define TICKS_TO_SECS(x, w)		((x) >> (w)->resolution)
> +
> +#define BCM_KONA_WDT_NAME		"bcm_kona_wdt"
> +
> +struct bcm_kona_wdt {
> +	void __iomem *base;
> +	/*
> +	 * One watchdog tick is 1/(2^resolution) seconds. Resolution can take
> +	 * the values 0-15, meaning one tick can be 1s to 30.52us. Our default
> +	 * resolution of 4 means one tick is 62.5ms.
> +	 *
> +	 * The watchdog counter is 20 bits. Depending on resolution, the maximum
> +	 * counter value of 0xfffff expires after about 12 days (resolution 0)
> +	 * down to only 32s (resolution 15). The default resolution of 4 gives
> +	 * us a maximum of about 18 hours and 12 minutes before the watchdog
> +	 * times out.
> +	 */
> +	int resolution;
> +	spinlock_t lock;
> +#ifdef CONFIG_BCM_KONA_WDT_DEBUG
> +	struct dentry *debugfs;
> +#endif
> +};
> +
> +#ifdef CONFIG_BCM_KONA_WDT_DEBUG
> +static unsigned long busy_count;
> +#endif
> +
> +static int secure_register_read(void __iomem *addr)
> +{
> +	uint32_t val;
> +	unsigned count = 0;
> +
> +	/*
> +	 * If the WD_LOAD_FLAG is set, the watchdog counter field is being
> +	 * updated in hardware. Once the WD timer is updated in hardware, it
> +	 * gets cleared.
> +	 */
> +	do {
> +		if (unlikely(count > 1))
> +			udelay(5);
> +		val = readl_relaxed(addr);
> +		count++;
> +	} while ((val & SECWDOG_WD_LOAD_FLAG) && count < SECWDOG_MAX_TRY);
> +
> +#ifdef CONFIG_BCM_KONA_WDT_DEBUG
> +	/* Remember the maximum number iterations due to WD_LOAD_FLAG */
> +	if (count > busy_count)
> +		busy_count = count;
> +#endif
> +
> +	/* This is the only place we return a negative value. */
> +	if (val & SECWDOG_WD_LOAD_FLAG)
> +		return -ETIMEDOUT;
> +
> +	/* We always mask out reserved bits. */
> +	val &= SECWDOG_RESERVED_MASK;
> +
> +	return val;
> +}
> +
> +#ifdef CONFIG_BCM_KONA_WDT_DEBUG
> +
> +static int bcm_kona_wdt_dbg_show(struct seq_file *s, void *data)
> +{
> +	int ctl_val, cur_val, ret;
> +	unsigned long flags;
> +	struct bcm_kona_wdt *wdt = s->private;
> +
> +	if (!wdt)
> +		return seq_puts(s, "No device pointer\n");
> +
> +	spin_lock_irqsave(&wdt->lock, flags);
> +	ctl_val = secure_register_read(wdt->base + SECWDOG_CTRL_REG);
> +	cur_val = secure_register_read(wdt->base + SECWDOG_COUNT_REG);
> +	spin_unlock_irqrestore(&wdt->lock, flags);
> +
> +	if (ctl_val < 0 || cur_val < 0) {
> +		ret = seq_puts(s, "Error accessing hardware\n");
> +	} else {
> +		int ctl, cur, ctl_sec, cur_sec, res;
> +
> +		ctl = ctl_val & SECWDOG_COUNT_MASK;
> +		res = (ctl_val & SECWDOG_RES_MASK) >> SECWDOG_CLKS_SHIFT;
> +		cur = cur_val & SECWDOG_COUNT_MASK;
> +		ctl_sec = TICKS_TO_SECS(ctl, wdt);
> +		cur_sec = TICKS_TO_SECS(cur, wdt);
> +		ret = seq_printf(s, "Resolution: %d / %d\n"
> +				"Control: %d s / %d (%#x) ticks\n"
> +				"Current: %d s / %d (%#x) ticks\n"
> +				"Busy count: %lu\n", res,
> +				wdt->resolution, ctl_sec, ctl, ctl, cur_sec,
> +				cur, cur, busy_count);
> +	}
> +
> +	return ret;
> +}
> +
> +static int bcm_kona_dbg_open(struct inode *inode, struct file *file)
> +{
> +	return single_open(file, bcm_kona_wdt_dbg_show, inode->i_private);
> +}
> +
> +static const struct file_operations bcm_kona_dbg_operations = {
> +	.open		= bcm_kona_dbg_open,
> +	.read		= seq_read,
> +	.llseek		= seq_lseek,
> +	.release	= single_release,
> +};
> +
> +static struct dentry *bcm_kona_wdt_debugfs_init(struct bcm_kona_wdt *wdt,
> +	struct watchdog_device *wdd)
> +{
> +	struct dentry *dir;
> +
> +	dir = debugfs_create_dir(BCM_KONA_WDT_NAME, NULL);
> +	if (IS_ERR_OR_NULL(dir))
> +		return NULL;
> +
> +	if (debugfs_create_file("info", S_IFREG | S_IRUGO, dir, wdt,
> +				&bcm_kona_dbg_operations))
> +		return dir;
> +
> +	/* Clean up */
> +	debugfs_remove_recursive(dir);
> +	return NULL;
> +}
> +
> +static void bcm_kona_debugfs_exit(struct dentry *dir)
> +{
> +	debugfs_remove_recursive(dir);
> +}
> +
> +#endif /* CONFIG_BCM_KONA_WDT_DEBUG */
> +
> +static int bcm_kona_wdt_ctrl_reg_modify(struct bcm_kona_wdt *wdt,
> +					unsigned mask, unsigned newval)
> +{
> +	int val;
> +	unsigned long flags;
> +	int ret = 0;
> +
> +	spin_lock_irqsave(&wdt->lock, flags);
> +
> +	val = secure_register_read(wdt->base + SECWDOG_CTRL_REG);
> +	if (val < 0) {
> +		ret = val;
> +	} else {
> +		val &= ~mask;
> +		val |= newval;
> +		writel_relaxed(val, wdt->base + SECWDOG_CTRL_REG);
> +	}
> +
> +	spin_unlock_irqrestore(&wdt->lock, flags);
> +
> +	return ret;
> +}
> +
> +static int bcm_kona_wdt_set_resolution_reg(struct bcm_kona_wdt *wdt)
> +{
> +	if (wdt->resolution > SECWDOG_MAX_RES)
> +		return -EINVAL;
> +
> +	return bcm_kona_wdt_ctrl_reg_modify(wdt, SECWDOG_RES_MASK,
> +					wdt->resolution << SECWDOG_CLKS_SHIFT);
> +}
> +
> +static int bcm_kona_wdt_set_timeout_reg(struct watchdog_device *wdog,
> +					unsigned watchdog_flags)
> +{
> +	struct bcm_kona_wdt *wdt = watchdog_get_drvdata(wdog);
> +
> +	return bcm_kona_wdt_ctrl_reg_modify(wdt, SECWDOG_COUNT_MASK,
> +					SECS_TO_TICKS(wdog->timeout, wdt) |
> +					watchdog_flags);
> +}
> +
> +static int bcm_kona_wdt_set_timeout(struct watchdog_device *wdog,
> +	unsigned int t)
> +{
> +	wdog->timeout = t;
> +	return 0;
> +}
> +
> +static unsigned int bcm_kona_wdt_get_timeleft(struct watchdog_device *wdog)
> +{
> +	struct bcm_kona_wdt *wdt = watchdog_get_drvdata(wdog);
> +	int val;
> +	unsigned long flags;
> +
> +	spin_lock_irqsave(&wdt->lock, flags);
> +	val = secure_register_read(wdt->base + SECWDOG_COUNT_REG);
> +	spin_unlock_irqrestore(&wdt->lock, flags);
> +
> +	if (val < 0)
> +		return val;
> +
> +	return TICKS_TO_SECS(val & SECWDOG_COUNT_MASK, wdt);
> +}
> +
> +static int bcm_kona_wdt_start(struct watchdog_device *wdog)
> +{
> +	return bcm_kona_wdt_set_timeout_reg(wdog,
> +					SECWDOG_EN_MASK | SECWDOG_SRSTEN_MASK);
> +}
> +
> +static int bcm_kona_wdt_stop(struct watchdog_device *wdog)
> +{
> +	struct bcm_kona_wdt *wdt = watchdog_get_drvdata(wdog);
> +
> +	return bcm_kona_wdt_ctrl_reg_modify(wdt, SECWDOG_EN_MASK |
> +					    SECWDOG_SRSTEN_MASK, 0);
> +}
> +
> +static struct watchdog_ops bcm_kona_wdt_ops = {
> +	.owner =	THIS_MODULE,
> +	.start =	bcm_kona_wdt_start,
> +	.stop =		bcm_kona_wdt_stop,
> +	.set_timeout =	bcm_kona_wdt_set_timeout,
> +	.get_timeleft =	bcm_kona_wdt_get_timeleft,
> +};
> +
> +static struct watchdog_info bcm_kona_wdt_info = {
> +	.options =	WDIOF_SETTIMEOUT | WDIOF_MAGICCLOSE |
> +			WDIOF_KEEPALIVEPING,
> +	.identity =	"Broadcom Kona Watchdog Timer",
> +};
> +
> +static struct watchdog_device bcm_kona_wdt_wdd = {
> +	.info =		&bcm_kona_wdt_info,
> +	.ops =		&bcm_kona_wdt_ops,
> +	.min_timeout =	1,
> +	.max_timeout =	SECWDOG_MAX_COUNT >> SECWDOG_DEFAULT_RESOLUTION,
> +	.timeout =	SECWDOG_MAX_COUNT >> SECWDOG_DEFAULT_RESOLUTION,
> +};
> +
> +static void bcm_kona_wdt_shutdown(struct platform_device *pdev)
> +{
> +	bcm_kona_wdt_stop(&bcm_kona_wdt_wdd);
> +}
> +
> +static int bcm_kona_wdt_probe(struct platform_device *pdev)
> +{
> +	struct device *dev = &pdev->dev;
> +	struct bcm_kona_wdt *wdt;
> +	struct resource *res;
> +	int ret;
> +
> +	wdt = devm_kzalloc(dev, sizeof(*wdt), GFP_KERNEL);
> +	if (!wdt)
> +		return -ENOMEM;
> +
> +	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> +	wdt->base = devm_ioremap_resource(dev, res);
> +	if (IS_ERR(wdt->base))
> +		return -ENODEV;
> +
> +	wdt->resolution = SECWDOG_DEFAULT_RESOLUTION;
> +	ret = bcm_kona_wdt_set_resolution_reg(wdt);
> +	if (ret) {
> +		dev_err(dev, "Failed to set resolution (error: %d)", ret);
> +		return ret;
> +	}
> +
> +	spin_lock_init(&wdt->lock);
> +	platform_set_drvdata(pdev, wdt);
> +	watchdog_set_drvdata(&bcm_kona_wdt_wdd, wdt);
> +
> +	ret = bcm_kona_wdt_set_timeout_reg(&bcm_kona_wdt_wdd, 0);
> +	if (ret) {
> +		dev_err(dev, "Failed set watchdog timeout");
> +		return ret;
> +	}
> +
> +	ret = watchdog_register_device(&bcm_kona_wdt_wdd);
> +	if (ret) {
> +		dev_err(dev, "Failed to register watchdog device");
> +		return ret;
> +	}
> +
> +#ifdef CONFIG_BCM_KONA_WDT_DEBUG
> +	wdt->debugfs = bcm_kona_wdt_debugfs_init(wdt, &bcm_kona_wdt_wdd);
> +#endif
> +	dev_dbg(dev, "Broadcom Kona Watchdog Timer");
> +
> +	return 0;
> +}
> +
> +static int bcm_kona_wdt_remove(struct platform_device *pdev)
> +{
> +#ifdef CONFIG_BCM_KONA_WDT_DEBUG
> +	struct bcm_kona_wdt *wdt = platform_get_drvdata(pdev);
> +
> +	if (wdt->debugfs)
> +		bcm_kona_debugfs_exit(wdt->debugfs);
> +#endif /* CONFIG_BCM_KONA_WDT_DEBUG */
> +	bcm_kona_wdt_shutdown(pdev);
> +	watchdog_unregister_device(&bcm_kona_wdt_wdd);
> +	dev_dbg(&pdev->dev, "Watchdog driver disabled");
> +
> +	return 0;
> +}
> +
> +static const struct of_device_id bcm_kona_wdt_of_match[] = {
> +	{ .compatible = "brcm,kona-wdt", },
> +	{},
> +};
> +MODULE_DEVICE_TABLE(of, bcm_kona_wdt_of_match);
> +
> +static struct platform_driver bcm_kona_wdt_driver = {
> +	.driver = {
> +			.name = BCM_KONA_WDT_NAME,
> +			.owner = THIS_MODULE,
> +			.of_match_table = bcm_kona_wdt_of_match,
> +		  },
> +	.probe = bcm_kona_wdt_probe,
> +	.remove = bcm_kona_wdt_remove,
> +	.shutdown = bcm_kona_wdt_shutdown,
> +};
> +
> +module_platform_driver(bcm_kona_wdt_driver);
> +
> +MODULE_ALIAS("platform:" BCM_KONA_WDT_NAME);
> +MODULE_AUTHOR("Markus Mayer <mmayer@...adcom.com>");
> +MODULE_DESCRIPTION("Broadcom Kona Watchdog Driver");
> +MODULE_LICENSE("GPL v2");
>

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