[U-Boot] [PATCH 1/2] at91sam9: add watchdog support

[Giulio Benetti <giulio.benetti@micronovasrl.com>]

Jean-Christophe PLAGNIOL-VILLARD wrote:

> Signed-off-by: Jean-Christophe PLAGNIOL-VILLARD <plagnioj@jcrosoft.com>
> ---
>  Makefile                             |    1 +
>  doc/README.at91                      |    9 ++++
>  drivers/serial/atmel_usart.c         |    4 +-
>  drivers/watchdog/Makefile            |   46 ++++++++++++++++++++
>  drivers/watchdog/at91sam9_wdt.c      |   79
>  ++++++++++++++++++++++++++++++++++
>  include/asm-arm/arch-at91/at91_wdt.h |   38 ++++++++++++++++
>  6 files changed, 176 insertions(+), 1 deletions(-)
>  create mode 100644 drivers/watchdog/Makefile
>  create mode 100644 drivers/watchdog/at91sam9_wdt.c
>  create mode 100644 include/asm-arm/arch-at91/at91_wdt.h
> 
> diff --git a/Makefile b/Makefile
> index fcf57f3..3e61417 100644
> --- a/Makefile
> +++ b/Makefile
> @@ -262,6 +262,7 @@ LIBS += drivers/rtc/librtc.a
>  LIBS += drivers/serial/libserial.a
>  LIBS += drivers/usb/libusb.a
>  LIBS += drivers/video/libvideo.a
> +LIBS += drivers/watchdog/libwatchdog.a
>  LIBS += common/libcommon.a
>  LIBS += libfdt/libfdt.a
>  LIBS += api/libapi.a
> diff --git a/doc/README.at91 b/doc/README.at91
> index 4e3928a..c883c7c 100644
> --- a/doc/README.at91
> +++ b/doc/README.at91
> @@ -2,6 +2,7 @@ Atmel AT91 Evaluation kits
>  
>  http://atmel.com/dyn/products/tools.asp?family_id=605#1443
>  
> +I. Board mapping & boot media
>  ------------------------------------------------------------------------------
>  AT91SAM9260EK & AT91SAM9XEEK
>  ------------------------------------------------------------------------------
> @@ -86,3 +87,11 @@ Environment variables
>  make at91sam9263ek_config            - use data flash (spi cs0) (default)
>  make at91sam9263ek_nandflash_config  - use nand flash
>  make at91sam9263ek_dataflash_cs0_config      - use data flash (spi cs0)
> +
> +II. Watchdog support
> +
> +     The watchdog wan only be activate once so you need to activate in the
> +     bootloader and in the bootstrap if you use it
> +
> +     The you can activate with
> +     CONFIG_AT91SAM9_WATCHDOG and CONFIG_HW_WATCHDOG
> diff --git a/drivers/serial/atmel_usart.c b/drivers/serial/atmel_usart.c
> index f3b146c..f50552a 100644
> --- a/drivers/serial/atmel_usart.c
> +++ b/drivers/serial/atmel_usart.c
> @@ -16,6 +16,7 @@
>   * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307 
>   USA */
>  #include <common.h>
> +#include <watchdog.h>
>  
>  #include <asm/io.h>
>  #include <asm/arch/clk.h>
> @@ -87,7 +88,8 @@ void serial_puts(const char *s)
>  
>  int serial_getc(void)
>  {
> -     while (!(usart3_readl(CSR) & USART3_BIT(RXRDY))) ;
> +     while (!(usart3_readl(CSR) & USART3_BIT(RXRDY)))
> +              WATCHDOG_RESET();
>  return usart3_readl(RHR);
>  }
>  
> diff --git a/drivers/watchdog/Makefile b/drivers/watchdog/Makefile
> new file mode 100644
> index 0000000..200968d
> --- /dev/null
> +++ b/drivers/watchdog/Makefile
> @@ -0,0 +1,46 @@
> +#
> +# (C) Copyright 2008
> +# Wolfgang Denk, DENX Software Engineering, wd at denx.de.
> +#
> +# See file CREDITS for list of people who contributed to this
> +# project.
> +#
> +# 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.
> +#
> +# You should have received a copy of the GNU General Public License
> +# along with this program; if not, write to the Free Software
> +# Foundation, Inc., 59 Temple Place, Suite 330, Boston,
> +# MA 02111-1307 USA
> +#
> +
> +include $(TOPDIR)/config.mk
> +
> +LIB  := $(obj)libwatchdog.a
> +
> +COBJS-$(CONFIG_AT91SAM9_WATCHDOG) += at91sam9_wdt.o
> +
> +COBJS        := $(COBJS-y)
> +SRCS := $(COBJS:.o=.c)
> +OBJS := $(addprefix $(obj),$(COBJS))
> +
> +all: $(LIB)
> +
> +$(LIB):      $(obj).depend $(OBJS)
> +     $(AR) $(ARFLAGS) $@ $(OBJS)
> +
> +#########################################################################
> +
> +# defines $(obj).depend target
> +include $(SRCTREE)/rules.mk
> +
> +sinclude $(obj).depend
> +
> +#########################################################################
> diff --git a/drivers/watchdog/at91sam9_wdt.c
> b/drivers/watchdog/at91sam9_wdt.c new file mode 100644
> index 0000000..5bb8b77
> --- /dev/null
> +++ b/drivers/watchdog/at91sam9_wdt.c
> @@ -0,0 +1,79 @@
> +/*
> + * [origin: Linux kernel drivers/watchdog/at91sam9_wdt.c]
> + *
> + * Watchdog driver for Atmel AT91SAM9x processors.
> + *
> + * Copyright (C) 2008 Jean-Christophe PLAGNIOL-VILLARD
> <plagnioj@jcrosoft.com> + * Copyright (C) 2008 Renaud CERRATO
> r.cerrato at til-technologies.fr + *
> + * 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.
> + */
> +
> +/*
> + * The Watchdog Timer Mode Register can be only written to once. If the
> + * timeout need to be set from U-Boot, be sure that the bootstrap doesn't
> + * write to this register. Inform Linux to it too
> + */
> +
> +#include <common.h>
> +#include <watchdog.h>
> +#include <asm/arch/hardware.h>
> +#include <asm/arch/io.h>
> +#include <asm/arch/at91_wdt.h>
> +
> +/*
> + * AT91SAM9 watchdog runs a 12bit counter @ 256Hz,
> + * use this to convert a watchdog
> + * value from/to milliseconds.
> + */
> +#define ms_to_ticks(t)       (((t << 8) / 1000) - 1)
> +#define ticks_to_ms(t)       (((t + 1) * 1000) >> 8)
> +
> +/* Hardware timeout in seconds */
> +#define WDT_HW_TIMEOUT 2
> +
> +/*
> + * Set the watchdog time interval in 1/256Hz (write-once)
> + * Counter is 12 bit.
> + */
> +static int at91_wdt_settimeout(unsigned int timeout)
> +{
> +     unsigned int reg;
> +     unsigned int mr;
> +
> +     /* Check if disabled */
> +     mr = at91_sys_read(AT91_WDT_MR);
> +     if (mr & AT91_WDT_WDDIS) {
> +             printf("sorry, watchdog is disabled\n");
> +             return -1;
> +     }
> +
> +     /*
> +      * All counting occurs at SLOW_CLOCK / 128 = 256 Hz
> +      *
> +      * Since WDV is a 12-bit counter, the maximum period is
> +      * 4096 / 256 = 16 seconds.
> +      */
> +     reg = AT91_WDT_WDRSTEN  /* causes watchdog reset */
> +             /* | AT91_WDT_WDRPROC   causes processor reset only */
> +             | AT91_WDT_WDDBGHLT             /* disabled in debug mode */
> +             | AT91_WDT_WDD                  /* restart at any time */
> +             | (timeout & AT91_WDT_WDV);     /* timer value */
> +     at91_sys_write(AT91_WDT_MR, reg);
> +
> +     return 0;
> +}
> +
> +void hw_watchdog_reset(void)
> +{
> +     at91_sys_write(AT91_WDT_CR, AT91_WDT_KEY | AT91_WDT_WDRSTT);
> +}
> +
> +void hw_watchdog_init(void)
> +{
> +     /* 16 seconds timer, resets enabled */
> +     at91_wdt_settimeout(ms_to_ticks(WDT_HW_TIMEOUT * 1000));
> +}
> diff --git a/include/asm-arm/arch-at91/at91_wdt.h
> b/include/asm-arm/arch-at91/at91_wdt.h new file mode 100644
> index 0000000..7e18537
> --- /dev/null
> +++ b/include/asm-arm/arch-at91/at91_wdt.h
> @@ -0,0 +1,38 @@
> +/*
> + * [origin: Linux kernel arch/arm/mach-at91/include/mach/at91_wdt.h]
> + *
> + * Copyright (C) 2008 Jean-Christophe PLAGNIOL-VILLARD
> <plagnioj@jcrosoft.com> + * Copyright (C) 2007 Andrew Victor
> + * Copyright (C) 2007 Atmel Corporation.
> + *
> + * Watchdog Timer (WDT) - System peripherals regsters.
> + * Based on AT91SAM9261 datasheet revision D.
> + *
> + * 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.
> + */
> +
> +#ifndef AT91_WDT_H
> +#define AT91_WDT_H
> +
> +#define AT91_WDT_CR          (AT91_WDT + 0x00)       /* Watchdog Control Register */
> +#define              AT91_WDT_WDRSTT         (1    << 0)             /* Restart */
> +#define              AT91_WDT_KEY            (0xa5 << 24)            /* KEY Password */
> +
> +#define AT91_WDT_MR          (AT91_WDT + 0x04)       /* Watchdog Mode Register */
> +#define              AT91_WDT_WDV            (0xfff << 0)            /* Counter Value */
> +#define              AT91_WDT_WDFIEN         (1     << 12)           /* Fault Interrupt Enable */
> +#define              AT91_WDT_WDRSTEN        (1     << 13)           /* Reset Processor */
> +#define              AT91_WDT_WDRPROC        (1     << 14)           /* Timer Restart */
> +#define              AT91_WDT_WDDIS          (1     << 15)           /* Watchdog Disable */
> +#define              AT91_WDT_WDD            (0xfff << 16)           /* Delta Value */
> +#define              AT91_WDT_WDDBGHLT       (1     << 28)           /* Debug Halt */
> +#define              AT91_WDT_WDIDLEHLT      (1     << 29)           /* Idle Halt */
> +
> +#define AT91_WDT_SR          (AT91_WDT + 0x08)       /* Watchdog Status Register */
> +#define              AT91_WDT_WDUNF          (1 << 0)                /* Watchdog Underflow */
> +#define              AT91_WDT_WDERR          (1 << 1)                /* Watchdog Error */
> +
> +#endif

In this way the linux driver won't work(the one by Renaud CERRATO).
Because it expects MR register not to be set, or to be set enabled.

After I don't agree refreshing watchdog inside atmel_usart.c
If u-boot hangs there instead of execute bootcmd, then the machine lies
there forever.
In my opinion we should put WATCHDOG_RESET() inside main_loop and nand write
and read.
What do you think?

Kind regards

-- 
Giulio Benetti
R&D
Micronova srl