On 07/23/2015 01:38 PM, Ariel D'Alessandro wrote:
Hi Guenter,
El 21/07/15 a las 21:51, Guenter Roeck escibió:
On 07/14/2015 05:50 PM, Ariel D'Alessandro wrote:
This commit adds support for the watchdog timer found in NXP LPC SoCs
family, which includes LPC18xx/LPC43xx. Other SoCs in that family may
share the same watchdog hardware.
Watchdog driver registers a restart handler that will restart the system
by performing an incorrect feed after ensuring the watchdog is enabled in
reset mode.
As watchdog cannot be disabled in hardware, driver's stop routine will
regularly send a keepalive ping using a timer.
Signed-off-by: Ariel D'Alessandro <ariel@xxxxxxxxxxxxxxxxxxxx>
Hi Ariel,
sorry for the delayed response. Comments below.
Guenter
---
drivers/watchdog/Kconfig | 11 ++
drivers/watchdog/Makefile | 1 +
drivers/watchdog/lpc18xx_wdt.c | 344
+++++++++++++++++++++++++++++++++++++++++
3 files changed, 356 insertions(+)
create mode 100644 drivers/watchdog/lpc18xx_wdt.c
diff --git a/drivers/watchdog/Kconfig b/drivers/watchdog/Kconfig
index 742fbbc..af5e2e3 100644
--- a/drivers/watchdog/Kconfig
+++ b/drivers/watchdog/Kconfig
@@ -547,6 +547,17 @@ config DIGICOLOR_WATCHDOG
To compile this driver as a module, choose M here: the
module will be called digicolor_wdt.
+config LPC18XX_WATCHDOG
+ tristate "LPC18xx/43xx Watchdog"
+ depends on ARCH_LPC18XX || COMPILE_TEST
+ select WATCHDOG_CORE
+ help
+ Say Y here if to include support for the watchdog timer
+ in NXP LPC SoCs family, which includes LPC18xx/LPC43xx
+ processors.
+ To compile this driver as a module, choose M here: the
+ module will be called lpc18xx_wdt.
+
# AVR32 Architecture
config AT32AP700X_WDT
diff --git a/drivers/watchdog/Makefile b/drivers/watchdog/Makefile
index 59ea9a1..1b0ef48 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-$(CONFIG_LPC18XX_WATCHDOG) += lpc18xx_wdt.o
# AVR32 Architecture
obj-$(CONFIG_AT32AP700X_WDT) += at32ap700x_wdt.o
diff --git a/drivers/watchdog/lpc18xx_wdt.c
b/drivers/watchdog/lpc18xx_wdt.c
new file mode 100644
index 0000000..2b489fc
--- /dev/null
+++ b/drivers/watchdog/lpc18xx_wdt.c
@@ -0,0 +1,344 @@
+/*
+ * NXP LPC18xx Watchdog Timer (WDT)
+ *
+ * Copyright (c) 2015 Ariel D'Alessandro <ariel@xxxxxxxxxxxxxxxxx>
+ *
+ * This program is free software; you can redistribute it and/or
modify it
+ * under the terms of the GNU General Public License version 2 as
published by
+ * the Free Software Foundation.
+ *
+ * Notes
+ * -----
+ * The Watchdog consists of a fixed divide-by-4 clock pre-scaler and
a 24-bit
+ * counter which decrements on every clock cycle.
+ *
+ */
+
+#include <linux/clk.h>
+#include <linux/io.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
+#include <linux/reboot.h>
+#include <linux/watchdog.h>
+
+/* Registers */
+#define LPC18XX_WDT_MOD 0x00
+#define LPC18XX_WDT_MOD_WDEN BIT(0)
+#define LPC18XX_WDT_MOD_WDRESET BIT(1)
+#define LPC18XX_WDT_MOD_WDTOF_MASK 0x04
Not used.
That's right. I'll remove it.
+
+#define LPC18XX_WDT_TC 0x04
+#define LPC18XX_WDT_TC_MIN 0xff
+#define LPC18XX_WDT_TC_MAX 0xffffff
+
+#define LPC18XX_WDT_FEED 0x08
+#define LPC18XX_WDT_FEED_MAGIC1 0xaa
+#define LPC18XX_WDT_FEED_MAGIC2 0x55
+
+#define LPC18XX_WDT_TV 0x0c
+
+/* Clock pre-scaler */
+#define LPC18XX_WDT_CLK_DIV 4
+
+/* Timeout values in seconds */
+#define LPC18XX_WDT_DEF_TIMEOUT 5
+
This is (still) really low for Linux. Something like min(30, max_timeout)
might make more sense.
Remember that hardware limits timeout to a maximum value of 5.
As you said before we could use a soft timer, but I not sure that's a
good idea. As Ezequiel said [0], it might be adding bloat and we must
consider that this watchdog controller is included in cortex-M MCUs.
[0] http://www.spinics.net/lists/linux-watchdog/msg06904.html
Further down you have
lpc18xx_wdt->wdt_dev.max_timeout = (LPC18XX_WDT_TC_MAX *
LPC18XX_WDT_CLK_DIV) / clk_rate;
which seems to contradict this statement. If the maximum timeout is 5 seconds,
why don't you set max_timeout to a fixed value of 5 seconds ?
Thanks,
Guenter
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