[PATCHv2] Add a simple watchdog 'framework' to Barebox

[PATCHv2] Add a simple watchdog 'framework' to Barebox

[Juergen Beisert]

This patch series add a very simple watchdog command and also a user of it
for the i.MX28 SoC. The watchdog driver might also work on i.MX23, but this
is not tested yet.

This version adds some error check and reporting, if the watchdog does not
work as expected.

The following changes since commit 5d44309c3f9ab24d3f12f0d571bb94725948f0ff:

  Merge branch 'for-next/resource-size' into next (2012-06-21 20:52:03 +0200)

are available in the git repository at:

  git://git.pengutronix.de/git/jbe/barebox.git next_add_watchdog_frameworkV2

for you to fetch changes up to db34cd3715b7cbce138ccffaa5490be2e31e1b3e:

  ARM/MXS: add a watchdog driver for i.MX28 (2012-06-22 11:45:42 +0200)

----------------------------------------------------------------
Juergen Beisert (2):
      Add a simple watchdog framework
      ARM/MXS: add a watchdog driver for i.MX28

 drivers/Kconfig            |    1 +
 drivers/Makefile           |    1 +
 drivers/watchdog/Kconfig   |   17 +++++++
 drivers/watchdog/Makefile  |    2 +
 drivers/watchdog/im28wd.c  |  121 ++++++++++++++++++++++++++++++++++++++++++++
 drivers/watchdog/wd_core.c |   58 +++++++++++++++++++++
 include/watchdog.h         |   18 +++++++
 7 files changed, 218 insertions(+)
 create mode 100644 drivers/watchdog/Kconfig
 create mode 100644 drivers/watchdog/Makefile
 create mode 100644 drivers/watchdog/im28wd.c
 create mode 100644 drivers/watchdog/wd_core.c
 create mode 100644 include/watchdog.h


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[PATCH 1/2] Add a simple watchdog framework

[Juergen Beisert]

This patch adds a simple wd command which can setup, trigger and stop a watchdog
on the platform.

Signed-off-by: Juergen Beisert <jbe@pengutronix.de>
---
 drivers/Kconfig            |    1 +
 drivers/Makefile           |    1 +
 drivers/watchdog/Kconfig   |   10 ++++++++
 drivers/watchdog/Makefile  |    1 +
 drivers/watchdog/wd_core.c |   58 ++++++++++++++++++++++++++++++++++++++++++++
 include/watchdog.h         |   18 ++++++++++++++
 6 files changed, 89 insertions(+)
 create mode 100644 drivers/watchdog/Kconfig
 create mode 100644 drivers/watchdog/Makefile
 create mode 100644 drivers/watchdog/wd_core.c
 create mode 100644 include/watchdog.h

diff --git a/drivers/Kconfig b/drivers/Kconfig
index 037b0d4..e193063 100644
--- a/drivers/Kconfig
+++ b/drivers/Kconfig
@@ -18,5 +18,6 @@ source "drivers/input/Kconfig"
 
 source "drivers/pwm/Kconfig"
 source "drivers/dma/Kconfig"
+source "drivers/watchdog/Kconfig"
 
 endmenu
diff --git a/drivers/Makefile b/drivers/Makefile
index f40b321..52a44c9 100644
--- a/drivers/Makefile
+++ b/drivers/Makefile
@@ -16,3 +16,4 @@ obj-y	+= eeprom/
 obj-$(CONFIG_PWM) += pwm/
 obj-y	+= input/
 obj-y	+= dma/
+obj-y	+= watchdog/
diff --git a/drivers/watchdog/Kconfig b/drivers/watchdog/Kconfig
new file mode 100644
index 0000000..b5970c9
--- /dev/null
+++ b/drivers/watchdog/Kconfig
@@ -0,0 +1,10 @@
+menuconfig WATCHDOG
+	bool "Watchdog support              "
+	help
+
+if WATCHDOG
+
+config WATCHDOG_CORE
+	bool
+
+endif
diff --git a/drivers/watchdog/Makefile b/drivers/watchdog/Makefile
new file mode 100644
index 0000000..7a446d7
--- /dev/null
+++ b/drivers/watchdog/Makefile
@@ -0,0 +1 @@
+obj-$(CONFIG_WATCHDOG_CORE) += wd_core.o
diff --git a/drivers/watchdog/wd_core.c b/drivers/watchdog/wd_core.c
new file mode 100644
index 0000000..50f1441
--- /dev/null
+++ b/drivers/watchdog/wd_core.c
@@ -0,0 +1,58 @@
+/*
+ * (c) 2012 Juergen Beisert <kernel@pengutronix.de>
+ *
+ * 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 <common.h>
+#include <command.h>
+#include <errno.h>
+#include <linux/ctype.h>
+#include <watchdog.h>
+
+static unsigned timeout = 20; /* timeout in [sec] */
+
+static int do_wd(int argc, char *argv[])
+{
+	int rc;
+
+	if (argc > 1) {
+		if (isdigit(*argv[1])) {
+			timeout = simple_strtoul(argv[1], NULL, 0);
+		} else {
+			printf("numerical parameter expected\n");
+			return 1;
+		}
+	}
+
+	rc = watchdog_set_timeout(timeout);
+	if (rc == -EINVAL) {
+		if (timeout == 0)
+			printf("Watchdog cannot be disabled\n");
+		else
+			printf("Timeout value out of range\n");
+		return rc;
+	}
+	return 0;
+}
+
+BAREBOX_CMD_HELP_START(wd)
+BAREBOX_CMD_HELP_USAGE("wd <seconds>\n")
+BAREBOX_CMD_HELP_SHORT("enable the watchdog to bark in <seconds> seconds. "
+		"When <seconds> is 0, the watchdog gets disabled,\n"
+		"without a parameter the watchdog will be re-triggered\n")
+BAREBOX_CMD_HELP_END
+
+BAREBOX_CMD_START(wd)
+	.cmd = do_wd,
+	.usage = "enable/disable/trigger the watchdog",
+	BAREBOX_CMD_HELP(cmd_wd_help)
+BAREBOX_CMD_END
diff --git a/include/watchdog.h b/include/watchdog.h
new file mode 100644
index 0000000..d052a10
--- /dev/null
+++ b/include/watchdog.h
@@ -0,0 +1,18 @@
+/*
+ * 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.
+ */
+
+#ifndef INCLUDE_WATCHDOG_H
+# define INCLUDE_WATCHDOG_H
+
+extern int watchdog_set_timeout(unsigned);
+
+#endif /* INCLUDE_WATCHDOG_H */
-- 
1.7.10


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[PATCH 2/2] ARM/MXS: add a watchdog driver for i.MX28

[Juergen Beisert]

Signed-off-by: Juergen Beisert <jbe@pengutronix.de>
---
 drivers/watchdog/Kconfig  |    7 +++
 drivers/watchdog/Makefile |    1 +
 drivers/watchdog/im28wd.c |  121 +++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 129 insertions(+)
 create mode 100644 drivers/watchdog/im28wd.c

diff --git a/drivers/watchdog/Kconfig b/drivers/watchdog/Kconfig
index b5970c9..b1a73c0 100644
--- a/drivers/watchdog/Kconfig
+++ b/drivers/watchdog/Kconfig
@@ -7,4 +7,11 @@ if WATCHDOG
 config WATCHDOG_CORE
 	bool
 
+config WATCHDOG_MXS28
+	bool "i.MX28"
+	depends on ARCH_IMX28
+	select WATCHDOG_CORE
+	help
+	  Add support for watchdog management for the i.MX28 SoC.
+
 endif
diff --git a/drivers/watchdog/Makefile b/drivers/watchdog/Makefile
index 7a446d7..b0d4d2a 100644
--- a/drivers/watchdog/Makefile
+++ b/drivers/watchdog/Makefile
@@ -1 +1,2 @@
 obj-$(CONFIG_WATCHDOG_CORE) += wd_core.o
+obj-$(CONFIG_WATCHDOG_MXS28) += im28wd.o
diff --git a/drivers/watchdog/im28wd.c b/drivers/watchdog/im28wd.c
new file mode 100644
index 0000000..b1c4809
--- /dev/null
+++ b/drivers/watchdog/im28wd.c
@@ -0,0 +1,121 @@
+/*
+ * (c) 2012 Juergen Beisert <kernel@pengutronix.de>
+ *
+ * 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.
+ *
+ * Note: this driver works for the i.MX28 SoC. It might work for the
+ * i.MX23 Soc as well, but is not tested yet.
+ */
+
+#include <common.h>
+#include <init.h>
+#include <io.h>
+#include <errno.h>
+#include <malloc.h>
+
+#define MXS_RTC_CTRL 0x0
+#define MXS_RTC_SET_ADDR 0x4
+#define MXS_RTC_CLR_ADDR 0x8
+# define MXS_RTC_CTRL_WATCHDOGEN (1 << 4)
+
+#define MXS_RTC_STAT 0x10
+# define MXS_RTC_STAT_WD_PRESENT (1 << 29)
+
+#define MXS_RTC_WATCHDOG 0x50
+
+#define MXS_RTC_PERSISTENT0 0x60
+/* dubious meaning from inside the SoC's firmware ROM */
+# define MXS_RTC_PERSISTENT0_EXT_RST (1 << 21)
+/* dubious meaning from inside the SoC's firmware ROM */
+# define MXS_RTC_PERSISTENT0_THM_RST (1 << 20)
+
+#define MXS_RTC_PERSISTENT1 0x70
+/* dubious meaning from inside the SoC's firmware ROM */
+# define MXS_RTC_PERSISTENT1_FORCE_UPDATER (1 << 31)
+
+#define MXS_RTC_DEBUG 0xc0
+
+#define WDOG_TICK_RATE 1000 /* the watchdog uses a 1 kHz clock rate */
+
+struct imx28_wd {
+	void __iomem *regs;
+	u32 timeout;
+};
+
+static struct imx28_wd *wd;
+
+/* note: 'timeout' in clock ticks */
+static void imx28_wd_set_timeout(const struct imx28_wd *p, unsigned timeout)
+{
+	void __iomem *base;
+
+	if (timeout) {
+		writel(timeout, p->regs + MXS_RTC_WATCHDOG);
+		base = p->regs + MXS_RTC_SET_ADDR;
+	} else {
+		base = p->regs + MXS_RTC_CLR_ADDR;
+	}
+	writel(MXS_RTC_CTRL_WATCHDOGEN, base + MXS_RTC_CTRL);
+	writel(MXS_RTC_PERSISTENT1_FORCE_UPDATER, base + MXS_RTC_PERSISTENT1);
+}
+
+/* note: 'timeout' in [seconds] */
+int watchdog_set_timeout(unsigned timeout)
+{
+	if (timeout > (ULONG_MAX / WDOG_TICK_RATE))
+		return -EINVAL;
+
+	imx28_wd_set_timeout(wd, timeout * WDOG_TICK_RATE);
+	return 0;
+}
+EXPORT_SYMBOL(watchdog_set_timeout);
+
+static int imx28_wd_probe(struct device_d *dev)
+{
+	struct imx28_wd *priv;
+
+	priv = xzalloc(sizeof(struct imx28_wd));
+	priv->regs = dev_request_mem_region(dev, 0);
+	priv->timeout = 20;
+	dev->priv = priv;
+	wd = priv;
+
+	if (!(readl(priv->regs + MXS_RTC_STAT) & MXS_RTC_STAT_WD_PRESENT)) {
+		free(priv);
+		return -ENODEV;
+	}
+
+	/* disable the debug feature to ensure a working WD */
+	writel(0x00000000, priv->regs + MXS_RTC_DEBUG);
+
+	return 0;
+}
+
+static void imx28_wd_remove(struct device_d *dev)
+{
+	struct imx28_wd *priv= dev->priv;
+	wd = NULL;
+	free(priv);
+}
+
+static struct driver_d imx28_wd_driver = {
+	.name   = "im28wd",
+	.probe  = imx28_wd_probe,
+	.remove = imx28_wd_remove,
+};
+
+static int imx28_wd_init(void)
+{
+	register_driver(&imx28_wd_driver);
+	return 0;
+}
+
+device_initcall(imx28_wd_init);
-- 
1.7.10


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Re: [PATCH 1/2] Add a simple watchdog framework

[Sascha Hauer]

On Fri, Jun 22, 2012 at 11:54:02AM +0200, Juergen Beisert wrote:
> This patch adds a simple wd command which can setup, trigger and stop a watchdog
> on the platform.
> 
> +static int do_wd(int argc, char *argv[])
> +{
> +	int rc;
> +
> +	if (argc > 1) {
> +		if (isdigit(*argv[1])) {
> +			timeout = simple_strtoul(argv[1], NULL, 0);
> +		} else {
> +			printf("numerical parameter expected\n");
> +			return 1;
> +		}
> +	}
> +
> +	rc = watchdog_set_timeout(timeout);
> +	if (rc == -EINVAL) {

Why do you check for -EINVAL only? This way all other errors will be
silently ignored.

> +		if (timeout == 0)
> +			printf("Watchdog cannot be disabled\n");
> +		else
> +			printf("Timeout value out of range\n");
> +		return rc;

Do not return negative error codes here. The shell will interpret
negative numbers as 'exit'. You have to return 1 for failure.

> +	}
> +	return 0;
> +}
> +
> +
> +#ifndef INCLUDE_WATCHDOG_H
> +# define INCLUDE_WATCHDOG_H
> +
> +extern int watchdog_set_timeout(unsigned);

extern is not needed here.

Sascha

-- 
Pengutronix e.K.                           |                             |
Industrial Linux Solutions                 | http://www.pengutronix.de/  |
Peiner Str. 6-8, 31137 Hildesheim, Germany | Phone: +49-5121-206917-0    |
Amtsgericht Hildesheim, HRA 2686           | Fax:   +49-5121-206917-5555 |

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Re: [PATCH 1/2] Add a simple watchdog framework

[Juergen Beisert]

Sascha Hauer wrote:
> On Fri, Jun 22, 2012 at 11:54:02AM +0200, Juergen Beisert wrote:
> > This patch adds a simple wd command which can setup, trigger and stop a
> > watchdog on the platform.
> >
> > +static int do_wd(int argc, char *argv[])
> > +{
> > +	int rc;
> > +
> > +	if (argc > 1) {
> > +		if (isdigit(*argv[1])) {
> > +			timeout = simple_strtoul(argv[1], NULL, 0);
> > +		} else {
> > +			printf("numerical parameter expected\n");
> > +			return 1;
> > +		}
> > +	}
> > +
> > +	rc = watchdog_set_timeout(timeout);
> > +	if (rc == -EINVAL) {
>
> Why do you check for -EINVAL only? This way all other errors will be
> silently ignored.

Are you sure we must handle other failure codes than -EINVAL here? The called 
function is very simple and only must distinguish "timeout != 0" and "timeout 
== 0". So, timeout can be "out of range" or - as you mentioned - some 
platforms cannot disable the watchdog anymore once it is enabled. Both 
results into -EINVAL, because the called function cannot use the given value. 
What else can happen?

> > +		if (timeout == 0)
> > +			printf("Watchdog cannot be disabled\n");
> > +		else
> > +			printf("Timeout value out of range\n");
> > +		return rc;
>
> Do not return negative error codes here. The shell will interpret
> negative numbers as 'exit'. You have to return 1 for failure.

Okay, missed that.

> > +	}
> > +	return 0;
> > +}
> > +
> > +
> > +#ifndef INCLUDE_WATCHDOG_H
> > +# define INCLUDE_WATCHDOG_H
> > +
> > +extern int watchdog_set_timeout(unsigned);
>
> extern is not needed here.

Okay.

jbe

-- 
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Linux Solutions for Science and Industry      | http://www.pengutronix.de/  |

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Re: [PATCH 1/2] Add a simple watchdog framework

[Sascha Hauer]

On Mon, Jun 25, 2012 at 02:45:43PM +0200, Juergen Beisert wrote:
> Sascha Hauer wrote:
> > On Fri, Jun 22, 2012 at 11:54:02AM +0200, Juergen Beisert wrote:
> > > This patch adds a simple wd command which can setup, trigger and stop a
> > > watchdog on the platform.
> > >
> > > +static int do_wd(int argc, char *argv[])
> > > +{
> > > +	int rc;
> > > +
> > > +	if (argc > 1) {
> > > +		if (isdigit(*argv[1])) {
> > > +			timeout = simple_strtoul(argv[1], NULL, 0);
> > > +		} else {
> > > +			printf("numerical parameter expected\n");
> > > +			return 1;
> > > +		}
> > > +	}
> > > +
> > > +	rc = watchdog_set_timeout(timeout);
> > > +	if (rc == -EINVAL) {
> >
> > Why do you check for -EINVAL only? This way all other errors will be
> > silently ignored.
> 
> Are you sure we must handle other failure codes than -EINVAL here? The called 
> function is very simple and only must distinguish "timeout != 0" and "timeout 
> == 0". So, timeout can be "out of range" or - as you mentioned - some 
> platforms cannot disable the watchdog anymore once it is enabled. Both 
> results into -EINVAL, because the called function cannot use the given value. 
> What else can happen?

Why should we only test for errors that we know and silently drop all others?

Somebody might think that -ENOSYS is the appropriate return value if the
watchdog can't be disabled. When such a patch is added nobody will
remember that our error handling only checks for a special error value.

Sascha


-- 
Pengutronix e.K.                           |                             |
Industrial Linux Solutions                 | http://www.pengutronix.de/  |
Peiner Str. 6-8, 31137 Hildesheim, Germany | Phone: +49-5121-206917-0    |
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Re: [PATCH 1/2] Add a simple watchdog framework

[Juergen Beisert]

Hi Sascha,

Sascha Hauer wrote:
> [...]
> > > > +
> > > > +	rc = watchdog_set_timeout(timeout);
> > > > +	if (rc == -EINVAL) {
> > >
> > > Why do you check for -EINVAL only? This way all other errors will be
> > > silently ignored.
> >
> > Are you sure we must handle other failure codes than -EINVAL here? The
> > called function is very simple and only must distinguish "timeout != 0"
> > and "timeout == 0". So, timeout can be "out of range" or - as you
> > mentioned - some platforms cannot disable the watchdog anymore once it is
> > enabled. Both results into -EINVAL, because the called function cannot
> > use the given value. What else can happen?
>
> Why should we only test for errors that we know and silently drop all
> others?

+1

> Somebody might think that -ENOSYS is the appropriate return value if the
> watchdog can't be disabled. When such a patch is added nobody will
> remember that our error handling only checks for a special error value.

If we accept every possible error value, then we also must move the readable 
error message into the called function (because only the called function 
knows the meaning of its returned value).
Otherwise we must force a specific return-value to give a correct error 
message to the user. But if we force a specific return-value (-EINVAL for 
example) then the -ENOSYS would violate the defined API.

jbe

-- 
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Linux Solutions for Science and Industry      | http://www.pengutronix.de/  |

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