[PATCH 0/2] watchdog: driver for BCM7038 and newer chips.

[PATCH 0/2] watchdog: driver for BCM7038 and newer chips.

[Justin Chen]

This driver is for a watchdog block contained in all Broadcom Set-top
Box chips since BCM7038. BCM7038 was made public during the 2004 CES,
and since then, many chips use this watchdog block including some cable
modem chips.

Patch 1: watchdog device tree binding documentation

Patch 2: watchdog driver

Justin Chen (2):
  watchdog: bcm7038: add device tree binding documentation
  watchdog: Watchdog driver for Broadcom Set-Top Box

 .../bindings/watchdog/brcm,bcm7038-wdt.txt         |  19 ++
 drivers/watchdog/Kconfig                           |   8 +
 drivers/watchdog/Makefile                          |   1 +
 drivers/watchdog/bcm7038_wdt.c                     | 253 +++++++++++++++++++++
 4 files changed, 281 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/watchdog/brcm,bcm7038-wdt.txt
 create mode 100644 drivers/watchdog/bcm7038_wdt.c

-- 
2.1.0

[PATCH 1/2] watchdog: bcm7038: add device tree binding documentation

[Justin Chen]

Add device tree binding docmentation for the watchdog hardware block
on bcm7038 and newer SoCs.

Signed-off-by: Justin Chen <justinpopo6@gmail.com>
---
 .../devicetree/bindings/watchdog/brcm,bcm7038-wdt.txt | 19 +++++++++++++++++++
 1 file changed, 19 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/watchdog/brcm,bcm7038-wdt.txt

diff --git a/Documentation/devicetree/bindings/watchdog/brcm,bcm7038-wdt.txt b/Documentation/devicetree/bindings/watchdog/brcm,bcm7038-wdt.txt
new file mode 100644
index 0000000..adb8260
--- /dev/null
+++ b/Documentation/devicetree/bindings/watchdog/brcm,bcm7038-wdt.txt
@@ -0,0 +1,19 @@
+BCM7038 Watchdog timer
+
+Required properties:
+
+- compatible : should be "brcm,bcm7038-wdt"
+- reg : Specifies base physical address and size of the registers.
+
+Optional properties:
+
+- clocks: the clock running the watchdog
+- clock-frequency: the rate of the clock
+
+Example:
+
+watchdog {
+	compatible = "brcm,bcm7038-wdt";
+	clocks = <&upg_fixed>;
+	reg = <0xf040a7e8 0x16>;
+};
-- 
2.1.0

Re: [PATCH 1/2] watchdog: bcm7038: add device tree binding documentation

[Guenter Roeck]

Hi Justin,

On 08/20/2015 10:41 AM, Justin Chen wrote:
> Add device tree binding docmentation for the watchdog hardware block
> on bcm7038 and newer SoCs.
>
> Signed-off-by: Justin Chen <justinpopo6@gmail.com>
> ---
>   .../devicetree/bindings/watchdog/brcm,bcm7038-wdt.txt | 19 +++++++++++++++++++
>   1 file changed, 19 insertions(+)
>   create mode 100644 Documentation/devicetree/bindings/watchdog/brcm,bcm7038-wdt.txt
>
> diff --git a/Documentation/devicetree/bindings/watchdog/brcm,bcm7038-wdt.txt b/Documentation/devicetree/bindings/watchdog/brcm,bcm7038-wdt.txt
> new file mode 100644
> index 0000000..adb8260
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/watchdog/brcm,bcm7038-wdt.txt
> @@ -0,0 +1,19 @@
> +BCM7038 Watchdog timer
> +
> +Required properties:
> +
> +- compatible : should be "brcm,bcm7038-wdt"
> +- reg : Specifies base physical address and size of the registers.
> +
> +Optional properties:
> +
> +- clocks: the clock running the watchdog
> +- clock-frequency: the rate of the clock

Is 'clock-frequency' really needed (and useful), or would it make more sense
to expect the user to configure a fixed clock if nothing else is available ?
How do other drivers handle this ?

Thanks,
Guenter

> +
> +Example:
> +
> +watchdog {
> +	compatible = "brcm,bcm7038-wdt";
> +	clocks = <&upg_fixed>;
> +	reg = <0xf040a7e8 0x16>;
> +};
>

Re: [PATCH 1/2] watchdog: bcm7038: add device tree binding documentation

[Justin Chen]

On Sun, Aug 23, 2015 at 08:32:21PM -0700, Guenter Roeck wrote:
> Hi Justin,
> 
> On 08/20/2015 10:41 AM, Justin Chen wrote:
> >Add device tree binding docmentation for the watchdog hardware block
> >on bcm7038 and newer SoCs.
> >
> >Signed-off-by: Justin Chen <justinpopo6@gmail.com>
> >---
> >  .../devicetree/bindings/watchdog/brcm,bcm7038-wdt.txt | 19 +++++++++++++++++++
> >  1 file changed, 19 insertions(+)
> >  create mode 100644 Documentation/devicetree/bindings/watchdog/brcm,bcm7038-wdt.txt
> >
> >diff --git a/Documentation/devicetree/bindings/watchdog/brcm,bcm7038-wdt.txt b/Documentation/devicetree/bindings/watchdog/brcm,bcm7038-wdt.txt
> >new file mode 100644
> >index 0000000..adb8260
> >--- /dev/null
> >+++ b/Documentation/devicetree/bindings/watchdog/brcm,bcm7038-wdt.txt
> >@@ -0,0 +1,19 @@
> >+BCM7038 Watchdog timer
> >+
> >+Required properties:
> >+
> >+- compatible : should be "brcm,bcm7038-wdt"
> >+- reg : Specifies base physical address and size of the registers.
> >+
> >+Optional properties:
> >+
> >+- clocks: the clock running the watchdog
> >+- clock-frequency: the rate of the clock
> 
> Is 'clock-frequency' really needed (and useful), or would it make more sense
> to expect the user to configure a fixed clock if nothing else is available ?
> How do other drivers handle this ?
> 
> Thanks,
> Guenter
> 
> >+
> >+Example:
> >+
> >+watchdog {
> >+	compatible = "brcm,bcm7038-wdt";
> >+	clocks = <&upg_fixed>;
> >+	reg = <0xf040a7e8 0x16>;
> >+};
> >
>

Hello Guenter,

> Is 'clock-frequency' really needed (and useful), or would it make more sense
> to expect the user to configure a fixed clock if nothing else is available ?
> How do other drivers handle this ?

The reason for 'clock-frequency' was for a case where our device tree did not
have clocks. Creating a new fixed clock for a single device seems unnecessary
compared to a 'clock-frequency' property. Their is a use for 'clock-frequency',
but it is not really necessary. However, this is my first linux patch, so I do 
not fully trust my judgement on this...

Looking at other drivers, none of them have both clock and clock-frequency.

Thank you for your time on reviewing the patch Guenter. Much appreciated!

Thanks,
Justin Chen

Re: [PATCH 1/2] watchdog: bcm7038: add device tree binding documentation

[Guenter Roeck]

Justin,

On Tue, Aug 25, 2015 at 10:55:40AM -0700, Justin Chen wrote:
> 
> Hello Guenter,
> 
> > Is 'clock-frequency' really needed (and useful), or would it make more sense
> > to expect the user to configure a fixed clock if nothing else is available ?
> > How do other drivers handle this ?
> 
> The reason for 'clock-frequency' was for a case where our device tree did not
> have clocks. Creating a new fixed clock for a single device seems unnecessary
> compared to a 'clock-frequency' property. Their is a use for 'clock-frequency',
> but it is not really necessary. However, this is my first linux patch, so I do 
> not fully trust my judgement on this...
> 

All that is needed for a fixed clock is a devicetree entry for it. Not sure
I understand your line of argument; you add a lot of complexity and code
just to avoid those few lines in the dts file (especially with 500+
"fixed-clock" nodes in other devicetree files).

Thanks,
Guenter

Re: [PATCH 1/2] watchdog: bcm7038: add device tree binding documentation

[Justin Chen]

On Tue, Aug 25, 2015 at 12:04:48PM -0700, Guenter Roeck wrote:
> Justin,
> 
> On Tue, Aug 25, 2015 at 10:55:40AM -0700, Justin Chen wrote:
> > 
> > Hello Guenter,
> > 
> > > Is 'clock-frequency' really needed (and useful), or would it make more sense
> > > to expect the user to configure a fixed clock if nothing else is available ?
> > > How do other drivers handle this ?
> > 
> > The reason for 'clock-frequency' was for a case where our device tree did not
> > have clocks. Creating a new fixed clock for a single device seems unnecessary
> > compared to a 'clock-frequency' property. Their is a use for 'clock-frequency',
> > but it is not really necessary. However, this is my first linux patch, so I do 
> > not fully trust my judgement on this...
> > 
> 
> All that is needed for a fixed clock is a devicetree entry for it. Not sure
> I understand your line of argument; you add a lot of complexity and code
> just to avoid those few lines in the dts file (especially with 500+
> "fixed-clock" nodes in other devicetree files).
> 
> Thanks,
> Guenter

Ok your argument makes sense. I will remove the clock-frequency property and 
modify the driver accordingly. Thank you for your feedback!

Thanks,
Justin

[PATCH 2/2] watchdog: Watchdog driver for Broadcom Set-Top Box

[Justin Chen]

Watchdog driver for Broadcom 7038 and newer chips.

Signed-off-by: Justin Chen <justinpopo6@gmail.com>
---
 drivers/watchdog/Kconfig       |   8 ++
 drivers/watchdog/Makefile      |   1 +
 drivers/watchdog/bcm7038_wdt.c | 253 +++++++++++++++++++++++++++++++++++++++++
 3 files changed, 262 insertions(+)
 create mode 100644 drivers/watchdog/bcm7038_wdt.c

diff --git a/drivers/watchdog/Kconfig b/drivers/watchdog/Kconfig
index 241fafd..4fbe8ab 100644
--- a/drivers/watchdog/Kconfig
+++ b/drivers/watchdog/Kconfig
@@ -1291,6 +1291,14 @@ config BCM_KONA_WDT_DEBUG
 
 	  If in doubt, say 'N'.
 
+config BCM7038_WDT
+	tristate "BCM7038 Watchdog"
+	select WATCHDOG_CORE
+	help
+	 Watchdog driver for the built-in hardware in Broadcom 7038 SoCs.
+
+	 Say 'Y or 'M' here to enable the driver.
+
 config IMGPDC_WDT
 	tristate "Imagination Technologies PDC Watchdog Timer"
 	depends on HAS_IOMEM
diff --git a/drivers/watchdog/Makefile b/drivers/watchdog/Makefile
index 59ea9a1..65d4169 100644
--- a/drivers/watchdog/Makefile
+++ b/drivers/watchdog/Makefile
@@ -66,6 +66,7 @@ obj-$(CONFIG_TEGRA_WATCHDOG) += tegra_wdt.o
 obj-$(CONFIG_MESON_WATCHDOG) += meson_wdt.o
 obj-$(CONFIG_MEDIATEK_WATCHDOG) += mtk_wdt.o
 obj-$(CONFIG_DIGICOLOR_WATCHDOG) += digicolor_wdt.o
+obj-$(CONFIG_BCM7038_WDT) += bcm7038_wdt.o
 
 # AVR32 Architecture
 obj-$(CONFIG_AT32AP700X_WDT) += at32ap700x_wdt.o
diff --git a/drivers/watchdog/bcm7038_wdt.c b/drivers/watchdog/bcm7038_wdt.c
new file mode 100644
index 0000000..a70730b
--- /dev/null
+++ b/drivers/watchdog/bcm7038_wdt.c
@@ -0,0 +1,253 @@
+/*
+ * Copyright (C) 2015 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; 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/module.h>
+#include <linux/init.h>
+#include <linux/io.h>
+#include <linux/platform_device.h>
+#include <linux/watchdog.h>
+#include <linux/clk.h>
+#include <linux/of.h>
+#include <linux/pm.h>
+
+#define WDT_START_1		0xff00
+#define WDT_START_2		0x00ff
+#define WDT_STOP_1		0xee00
+#define WDT_STOP_2		0x00ee
+
+#define WDT_TIMEOUT_REG		0x0
+#define WDT_CMD_REG		0x4
+
+#define WDT_MIN_TIMEOUT		1 /* seconds */
+#define WDT_DEFAULT_TIMEOUT	30 /* seconds */
+#define WDT_DEFAULT_RATE	27000000
+
+struct bcm7038_watchdog {
+	void __iomem		*reg;
+	struct clk		*wdt_clk;
+	struct watchdog_device	wdd;
+	u32			hz;
+};
+
+static bool nowayout = WATCHDOG_NOWAYOUT;
+
+static unsigned long bcm7038_wdt_get_rate(struct bcm7038_watchdog *wdt)
+{
+	/* if clock is missing return hz */
+	if (!wdt->wdt_clk)
+		return wdt->hz;
+
+	return clk_get_rate(wdt->wdt_clk);
+
+}
+
+static void bcm7038_wdt_set_timeout_reg(struct watchdog_device *wdog)
+{
+	struct bcm7038_watchdog *wdt = watchdog_get_drvdata(wdog);
+	u32 timeout;
+
+	timeout = bcm7038_wdt_get_rate(wdt) * wdog->timeout;
+
+	writel(timeout, wdt->reg + WDT_TIMEOUT_REG);
+}
+
+static int bcm7038_wdt_ping(struct watchdog_device *wdog)
+{
+	struct bcm7038_watchdog *wdt = watchdog_get_drvdata(wdog);
+
+	writel(WDT_START_1, wdt->reg + WDT_CMD_REG);
+	writel(WDT_START_2, wdt->reg + WDT_CMD_REG);
+
+	return 0;
+}
+
+static int bcm7038_wdt_start(struct watchdog_device *wdog)
+{
+	bcm7038_wdt_set_timeout_reg(wdog);
+	bcm7038_wdt_ping(wdog);
+
+	return 0;
+}
+
+static int bcm7038_wdt_stop(struct watchdog_device *wdog)
+{
+	struct bcm7038_watchdog *wdt = watchdog_get_drvdata(wdog);
+
+	writel(WDT_STOP_1, wdt->reg + WDT_CMD_REG);
+	writel(WDT_STOP_2, wdt->reg + WDT_CMD_REG);
+
+	return 0;
+}
+
+static int bcm7038_wdt_set_timeout(struct watchdog_device *wdog,
+					unsigned int t)
+{
+	if (watchdog_timeout_invalid(wdog, t))
+		return -EINVAL;
+
+	/* Can't modify timeout value if watchdog timer is running */
+	bcm7038_wdt_stop(wdog);
+	wdog->timeout = t;
+	bcm7038_wdt_start(wdog);
+
+	return 0;
+}
+
+static unsigned int bcm7038_wdt_get_timeleft(struct watchdog_device *wdog)
+{
+	struct bcm7038_watchdog *wdt = watchdog_get_drvdata(wdog);
+	u32 time_left;
+
+	time_left = readl(wdt->reg + WDT_CMD_REG);
+
+	return time_left / bcm7038_wdt_get_rate(wdt);
+}
+
+static struct watchdog_info bcm7038_wdt_info = {
+	.identity	= "Broadcom Watchdog Timer",
+	.options	= WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING |
+				WDIOF_MAGICCLOSE
+};
+
+static struct watchdog_ops bcm7038_wdt_ops = {
+	.owner		= THIS_MODULE,
+	.start		= bcm7038_wdt_start,
+	.stop		= bcm7038_wdt_stop,
+	.set_timeout	= bcm7038_wdt_set_timeout,
+	.get_timeleft	= bcm7038_wdt_get_timeleft,
+};
+
+static int bcm7038_wdt_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct device_node *np = dev->of_node;
+	struct bcm7038_watchdog *wdt;
+	struct resource *res;
+	unsigned long wdt_rate;
+	int err;
+
+	wdt = devm_kzalloc(dev, sizeof(*wdt), GFP_KERNEL);
+	if (!wdt)
+		return -ENOMEM;
+
+	platform_set_drvdata(pdev, wdt);
+
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	wdt->reg = devm_ioremap_resource(dev, res);
+	if (IS_ERR(wdt->reg))
+		return PTR_ERR(wdt->reg);
+
+	wdt->wdt_clk = devm_clk_get(dev, NULL);
+	/* If unable to get clock, set clock to NULL */
+	if (IS_ERR(wdt->wdt_clk)) {
+		wdt->wdt_clk = NULL;
+		err = of_property_read_u32(np, "clock-frequency", &wdt->hz);
+		if (err) {
+			wdt->hz = WDT_DEFAULT_RATE;
+			dev_info(dev, "Using default frequency\n");
+		}
+	}
+
+	clk_prepare_enable(wdt->wdt_clk);
+
+	wdt_rate = bcm7038_wdt_get_rate(wdt);
+
+	wdt->wdd.info		= &bcm7038_wdt_info;
+	wdt->wdd.ops		= &bcm7038_wdt_ops;
+	wdt->wdd.min_timeout	= WDT_MIN_TIMEOUT;
+	wdt->wdd.timeout	= WDT_DEFAULT_TIMEOUT;
+	wdt->wdd.max_timeout	= (0xffffffff / wdt_rate);
+	wdt->wdd.parent		= dev;
+	watchdog_set_drvdata(&wdt->wdd, wdt);
+
+	err = watchdog_register_device(&wdt->wdd);
+	if (err) {
+		dev_err(dev, "Failed to register watchdog device\n");
+		return err;
+	}
+
+	dev_info(dev, "Registered Broadcom Watchdog\n");
+
+	return 0;
+}
+
+static int bcm7038_wdt_remove(struct platform_device *pdev)
+{
+	struct bcm7038_watchdog *wdt = platform_get_drvdata(pdev);
+
+	if (!nowayout)
+		bcm7038_wdt_stop(&wdt->wdd);
+
+	watchdog_unregister_device(&wdt->wdd);
+	clk_disable_unprepare(wdt->wdt_clk);
+
+	return 0;
+}
+
+#ifdef CONFIG_PM_SLEEP
+static int bcm7038_wdt_suspend(struct device *dev)
+{
+	struct bcm7038_watchdog *wdt = dev_get_drvdata(dev);
+
+	if (watchdog_active(&wdt->wdd))
+		return bcm7038_wdt_stop(&wdt->wdd);
+
+	return 0;
+}
+
+static int bcm7038_wdt_resume(struct device *dev)
+{
+	struct bcm7038_watchdog *wdt = dev_get_drvdata(dev);
+
+	if (watchdog_active(&wdt->wdd))
+		return bcm7038_wdt_start(&wdt->wdd);
+
+	return 0;
+}
+#endif
+
+static SIMPLE_DEV_PM_OPS(bcm7038_wdt_pm_ops, bcm7038_wdt_suspend,
+				bcm7038_wdt_resume);
+
+static void bcm7038_wdt_shutdown(struct platform_device *pdev)
+{
+	struct bcm7038_watchdog *wdt = platform_get_drvdata(pdev);
+
+	if (watchdog_active(&wdt->wdd))
+		bcm7038_wdt_stop(&wdt->wdd);
+}
+
+static const struct of_device_id bcm7038_wdt_match[] = {
+	{ .compatible = "brcm,bcm7038-wdt" },
+	{},
+};
+
+static struct platform_driver bcm7038_wdt_driver = {
+	.probe		= bcm7038_wdt_probe,
+	.remove		= bcm7038_wdt_remove,
+	.shutdown	= bcm7038_wdt_shutdown,
+	.driver		= {
+		.name		= "bcm7038-wdt",
+		.of_match_table	= bcm7038_wdt_match,
+		.pm		= &bcm7038_wdt_pm_ops,
+	}
+};
+module_platform_driver(bcm7038_wdt_driver);
+
+module_param(nowayout, bool, 0);
+MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="
+	__MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
+MODULE_LICENSE("GPL v2");
+MODULE_DESCRIPTION("Driver for Broadcom 7038 SoCs Watchdog");
+MODULE_AUTHOR("Justin Chen");
-- 
2.1.0

Re: [PATCH 2/2] watchdog: Watchdog driver for Broadcom Set-Top Box

[Guenter Roeck]

Hi Justin,

On 08/20/2015 10:41 AM, Justin Chen wrote:
> Watchdog driver for Broadcom 7038 and newer chips.
>
> Signed-off-by: Justin Chen <justinpopo6@gmail.com>

Looks pretty good. Couple of comments below.

Thanks,
Guenter

> ---
>   drivers/watchdog/Kconfig       |   8 ++
>   drivers/watchdog/Makefile      |   1 +
>   drivers/watchdog/bcm7038_wdt.c | 253 +++++++++++++++++++++++++++++++++++++++++
>   3 files changed, 262 insertions(+)
>   create mode 100644 drivers/watchdog/bcm7038_wdt.c
>
> diff --git a/drivers/watchdog/Kconfig b/drivers/watchdog/Kconfig
> index 241fafd..4fbe8ab 100644
> --- a/drivers/watchdog/Kconfig
> +++ b/drivers/watchdog/Kconfig
> @@ -1291,6 +1291,14 @@ config BCM_KONA_WDT_DEBUG
>
>   	  If in doubt, say 'N'.
>
> +config BCM7038_WDT
> +	tristate "BCM7038 Watchdog"
> +	select WATCHDOG_CORE
> +	help
> +	 Watchdog driver for the built-in hardware in Broadcom 7038 SoCs.
> +
> +	 Say 'Y or 'M' here to enable the driver.
> +
>   config IMGPDC_WDT
>   	tristate "Imagination Technologies PDC Watchdog Timer"
>   	depends on HAS_IOMEM
> diff --git a/drivers/watchdog/Makefile b/drivers/watchdog/Makefile
> index 59ea9a1..65d4169 100644
> --- a/drivers/watchdog/Makefile
> +++ b/drivers/watchdog/Makefile
> @@ -66,6 +66,7 @@ obj-$(CONFIG_TEGRA_WATCHDOG) += tegra_wdt.o
>   obj-$(CONFIG_MESON_WATCHDOG) += meson_wdt.o
>   obj-$(CONFIG_MEDIATEK_WATCHDOG) += mtk_wdt.o
>   obj-$(CONFIG_DIGICOLOR_WATCHDOG) += digicolor_wdt.o
> +obj-$(CONFIG_BCM7038_WDT) += bcm7038_wdt.o
>
Can you try to insert this in alphabetic order ?

>   # AVR32 Architecture
>   obj-$(CONFIG_AT32AP700X_WDT) += at32ap700x_wdt.o
> diff --git a/drivers/watchdog/bcm7038_wdt.c b/drivers/watchdog/bcm7038_wdt.c
> new file mode 100644
> index 0000000..a70730b
> --- /dev/null
> +++ b/drivers/watchdog/bcm7038_wdt.c
> @@ -0,0 +1,253 @@
> +/*
> + * Copyright (C) 2015 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; 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/module.h>
> +#include <linux/init.h>
> +#include <linux/io.h>
> +#include <linux/platform_device.h>
> +#include <linux/watchdog.h>
> +#include <linux/clk.h>
> +#include <linux/of.h>
> +#include <linux/pm.h>
> +
Please order include files in alphabetic order.

> +#define WDT_START_1		0xff00
> +#define WDT_START_2		0x00ff
> +#define WDT_STOP_1		0xee00
> +#define WDT_STOP_2		0x00ee
> +
> +#define WDT_TIMEOUT_REG		0x0
> +#define WDT_CMD_REG		0x4
> +
> +#define WDT_MIN_TIMEOUT		1 /* seconds */
> +#define WDT_DEFAULT_TIMEOUT	30 /* seconds */
> +#define WDT_DEFAULT_RATE	27000000
> +
> +struct bcm7038_watchdog {
> +	void __iomem		*reg;

'base' would be a better name for this variable.

> +	struct clk		*wdt_clk;
> +	struct watchdog_device	wdd;
> +	u32			hz;

How about "rate" ?

> +};
> +
> +static bool nowayout = WATCHDOG_NOWAYOUT;
> +
> +static unsigned long bcm7038_wdt_get_rate(struct bcm7038_watchdog *wdt)
> +{
> +	/* if clock is missing return hz */
> +	if (!wdt->wdt_clk)
> +		return wdt->hz;
> +
> +	return clk_get_rate(wdt->wdt_clk);
> +
Unnecessary empty line.

This is unnecessary complex. See below.

> +}
> +
> +static void bcm7038_wdt_set_timeout_reg(struct watchdog_device *wdog)
> +{
> +	struct bcm7038_watchdog *wdt = watchdog_get_drvdata(wdog);
> +	u32 timeout;
> +
> +	timeout = bcm7038_wdt_get_rate(wdt) * wdog->timeout;
> +
> +	writel(timeout, wdt->reg + WDT_TIMEOUT_REG);
> +}
> +
> +static int bcm7038_wdt_ping(struct watchdog_device *wdog)
> +{
> +	struct bcm7038_watchdog *wdt = watchdog_get_drvdata(wdog);
> +
> +	writel(WDT_START_1, wdt->reg + WDT_CMD_REG);
> +	writel(WDT_START_2, wdt->reg + WDT_CMD_REG);
> +
> +	return 0;
> +}
> +
> +static int bcm7038_wdt_start(struct watchdog_device *wdog)
> +{
> +	bcm7038_wdt_set_timeout_reg(wdog);
> +	bcm7038_wdt_ping(wdog);
> +
> +	return 0;
> +}
> +
> +static int bcm7038_wdt_stop(struct watchdog_device *wdog)
> +{
> +	struct bcm7038_watchdog *wdt = watchdog_get_drvdata(wdog);
> +
> +	writel(WDT_STOP_1, wdt->reg + WDT_CMD_REG);
> +	writel(WDT_STOP_2, wdt->reg + WDT_CMD_REG);
> +
> +	return 0;
> +}
> +
> +static int bcm7038_wdt_set_timeout(struct watchdog_device *wdog,
> +					unsigned int t)

Please align continuation lines to '('.

> +{
> +	if (watchdog_timeout_invalid(wdog, t))
> +		return -EINVAL;
> +
Unnecessary; checked by infrastructure.

> +	/* Can't modify timeout value if watchdog timer is running */
> +	bcm7038_wdt_stop(wdog);
> +	wdog->timeout = t;
> +	bcm7038_wdt_start(wdog);
> +
> +	return 0;
> +}
> +
> +static unsigned int bcm7038_wdt_get_timeleft(struct watchdog_device *wdog)
> +{
> +	struct bcm7038_watchdog *wdt = watchdog_get_drvdata(wdog);
> +	u32 time_left;
> +
> +	time_left = readl(wdt->reg + WDT_CMD_REG);
> +
> +	return time_left / bcm7038_wdt_get_rate(wdt);
> +}
> +
> +static struct watchdog_info bcm7038_wdt_info = {
> +	.identity	= "Broadcom Watchdog Timer",

I would suggest "Broadcom BCM7038 Watchdog Timer", to be in line with
other Broadcom watchdog drivers.

> +	.options	= WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING |
> +				WDIOF_MAGICCLOSE
> +};
> +
> +static struct watchdog_ops bcm7038_wdt_ops = {
> +	.owner		= THIS_MODULE,
> +	.start		= bcm7038_wdt_start,
> +	.stop		= bcm7038_wdt_stop,
> +	.set_timeout	= bcm7038_wdt_set_timeout,
> +	.get_timeleft	= bcm7038_wdt_get_timeleft,
> +};
> +
> +static int bcm7038_wdt_probe(struct platform_device *pdev)
> +{
> +	struct device *dev = &pdev->dev;
> +	struct device_node *np = dev->of_node;
> +	struct bcm7038_watchdog *wdt;
> +	struct resource *res;
> +	unsigned long wdt_rate;
> +	int err;
> +
> +	wdt = devm_kzalloc(dev, sizeof(*wdt), GFP_KERNEL);
> +	if (!wdt)
> +		return -ENOMEM;
> +
> +	platform_set_drvdata(pdev, wdt);
> +
> +	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> +	wdt->reg = devm_ioremap_resource(dev, res);
> +	if (IS_ERR(wdt->reg))
> +		return PTR_ERR(wdt->reg);
> +
> +	wdt->wdt_clk = devm_clk_get(dev, NULL);
> +	/* If unable to get clock, set clock to NULL */
> +	if (IS_ERR(wdt->wdt_clk)) {
> +		wdt->wdt_clk = NULL;
> +		err = of_property_read_u32(np, "clock-frequency", &wdt->hz);
> +		if (err) {
> +			wdt->hz = WDT_DEFAULT_RATE;
> +			dev_info(dev, "Using default frequency\n");
> +		}
> +	}

Way too complex. I would suggest to use something like

	if (!IS_ERR(clk)) {
		wdt->hz = clk_get_rate(wdt->wdt_clk);
	} else {
		wdt->wdt_clk = NULL;
		err = of_property_read_u32(np, "clock-frequency", &wdt->hz);
		if (err) {
			wdt->hz = WDT_DEFAULT_RATE;
			dev_info(dev, "Can not determine clock frequency, using default\n");
		}
	}

Then just use wdt->hz (or better wdt->rate) in the rest of the code.

Some drivers check if clk_get_rate() returns 0; might be a good idea to do this here
as well.

> +
> +	clk_prepare_enable(wdt->wdt_clk);
> +
You may have to move above code to here, and there is no need to call
clk_prepare_enable() if the clock isn't there.

> +	wdt_rate = bcm7038_wdt_get_rate(wdt);
> +

With the above, I think bcm7038_wdt_get_rate() is unnecessary. You can just use wdt->hz.

> +	wdt->wdd.info		= &bcm7038_wdt_info;
> +	wdt->wdd.ops		= &bcm7038_wdt_ops;
> +	wdt->wdd.min_timeout	= WDT_MIN_TIMEOUT;
> +	wdt->wdd.timeout	= WDT_DEFAULT_TIMEOUT;
> +	wdt->wdd.max_timeout	= (0xffffffff / wdt_rate);

Unnecessary ( ).

> +	wdt->wdd.parent		= dev;
> +	watchdog_set_drvdata(&wdt->wdd, wdt);
> +
> +	err = watchdog_register_device(&wdt->wdd);
> +	if (err) {
> +		dev_err(dev, "Failed to register watchdog device\n");
> +		return err;
> +	}
> +
> +	dev_info(dev, "Registered Broadcom Watchdog\n");
> +
BCM7038 ?

> +	return 0;
> +}
> +
> +static int bcm7038_wdt_remove(struct platform_device *pdev)
> +{
> +	struct bcm7038_watchdog *wdt = platform_get_drvdata(pdev);
> +
> +	if (!nowayout)
> +		bcm7038_wdt_stop(&wdt->wdd);
> +
> +	watchdog_unregister_device(&wdt->wdd);
> +	clk_disable_unprepare(wdt->wdt_clk);
> +
> +	return 0;
> +}
> +
> +#ifdef CONFIG_PM_SLEEP
> +static int bcm7038_wdt_suspend(struct device *dev)
> +{
> +	struct bcm7038_watchdog *wdt = dev_get_drvdata(dev);
> +
> +	if (watchdog_active(&wdt->wdd))
> +		return bcm7038_wdt_stop(&wdt->wdd);
> +
> +	return 0;
> +}
> +
> +static int bcm7038_wdt_resume(struct device *dev)
> +{
> +	struct bcm7038_watchdog *wdt = dev_get_drvdata(dev);
> +
> +	if (watchdog_active(&wdt->wdd))
> +		return bcm7038_wdt_start(&wdt->wdd);
> +
> +	return 0;
> +}
> +#endif
> +
> +static SIMPLE_DEV_PM_OPS(bcm7038_wdt_pm_ops, bcm7038_wdt_suspend,
> +				bcm7038_wdt_resume);
> +
> +static void bcm7038_wdt_shutdown(struct platform_device *pdev)
> +{
> +	struct bcm7038_watchdog *wdt = platform_get_drvdata(pdev);
> +
> +	if (watchdog_active(&wdt->wdd))
> +		bcm7038_wdt_stop(&wdt->wdd);
> +}
> +
> +static const struct of_device_id bcm7038_wdt_match[] = {
> +	{ .compatible = "brcm,bcm7038-wdt" },
> +	{},
> +};
> +
> +static struct platform_driver bcm7038_wdt_driver = {
> +	.probe		= bcm7038_wdt_probe,
> +	.remove		= bcm7038_wdt_remove,
> +	.shutdown	= bcm7038_wdt_shutdown,
> +	.driver		= {
> +		.name		= "bcm7038-wdt",
> +		.of_match_table	= bcm7038_wdt_match,
> +		.pm		= &bcm7038_wdt_pm_ops,
> +	}
> +};
> +module_platform_driver(bcm7038_wdt_driver);
> +
> +module_param(nowayout, bool, 0);
> +MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="
> +	__MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
> +MODULE_LICENSE("GPL v2");
> +MODULE_DESCRIPTION("Driver for Broadcom 7038 SoCs Watchdog");
> +MODULE_AUTHOR("Justin Chen");
>