linux-kernel - Re: [PATCH v6 2/2] watchdog: Add Renesas RZ/N1 Watchdog driver

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Date:   Wed, 27 Apr 2022 15:36:03 +0200
From:   Jean-Jacques Hiblot <jjhiblot@...phandler.com>
To:     Guenter Roeck <linux@...ck-us.net>, <wim@...ux-watchdog.org>,
        <geert+renesas@...der.be>, <tzungbi@...nel.org>,
        <linux-watchdog@...r.kernel.org>
CC:     <linux-renesas-soc@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>,
        Phil Edworthy <phil.edworthy@...esas.com>
Subject: Re: [PATCH v6 2/2] watchdog: Add Renesas RZ/N1 Watchdog driver


On 27/04/2022 15:03, Guenter Roeck wrote:
> On 4/13/22 01:25, Jean-Jacques Hiblot wrote:
>> From: Phil Edworthy <phil.edworthy@...esas.com>
>>
>> This is a driver for the standard WDT on the RZ/N1 devices. This WDT has
>> very limited timeout capabilities. However, it can reset the device.
>> To do so, the corresponding bits in the SysCtrl RSTEN register need to
>> be enabled. This is not done by this driver.
>>
>> Signed-off-by: Phil Edworthy <phil.edworthy@...esas.com>
>> Signed-off-by: Jean-Jacques Hiblot <jjhiblot@...phandler.com>
>> Reviewed-by: Tzung-Bi Shih <tzungbi@...nel.org>
>> ---
>>   drivers/watchdog/Kconfig    |   8 ++
>>   drivers/watchdog/Makefile   |   1 +
>>   drivers/watchdog/rzn1_wdt.c | 203 ++++++++++++++++++++++++++++++++++++
>>   3 files changed, 212 insertions(+)
>>   create mode 100644 drivers/watchdog/rzn1_wdt.c
>>
>> diff --git a/drivers/watchdog/Kconfig b/drivers/watchdog/Kconfig
>> index c4e82a8d863f..4d5e503c8950 100644
>> --- a/drivers/watchdog/Kconfig
>> +++ b/drivers/watchdog/Kconfig
>> @@ -883,6 +883,14 @@ config RENESAS_RZAWDT
>>         This driver adds watchdog support for the integrated 
>> watchdogs in the
>>         Renesas RZ/A SoCs. These watchdogs can be used to reset a 
>> system.
>>   +config RENESAS_RZN1WDT
>> +    tristate "Renesas RZ/N1 watchdog"
>> +    depends on ARCH_RENESAS || COMPILE_TEST
>> +    select WATCHDOG_CORE
>> +    help
>> +      This driver adds watchdog support for the integrated watchdogs 
>> in the
>> +      Renesas RZ/N1 SoCs. These watchdogs can be used to reset a 
>> system.
>> +
>>   config RENESAS_RZG2LWDT
>>       tristate "Renesas RZ/G2L WDT Watchdog"
>>       depends on ARCH_RENESAS || COMPILE_TEST
>> diff --git a/drivers/watchdog/Makefile b/drivers/watchdog/Makefile
>> index f7da867e8782..38d38564f47b 100644
>> --- a/drivers/watchdog/Makefile
>> +++ b/drivers/watchdog/Makefile
>> @@ -84,6 +84,7 @@ obj-$(CONFIG_LPC18XX_WATCHDOG) += lpc18xx_wdt.o
>>   obj-$(CONFIG_BCM7038_WDT) += bcm7038_wdt.o
>>   obj-$(CONFIG_RENESAS_WDT) += renesas_wdt.o
>>   obj-$(CONFIG_RENESAS_RZAWDT) += rza_wdt.o
>> +obj-$(CONFIG_RENESAS_RZN1WDT) += rzn1_wdt.o
>>   obj-$(CONFIG_RENESAS_RZG2LWDT) += rzg2l_wdt.o
>>   obj-$(CONFIG_ASPEED_WATCHDOG) += aspeed_wdt.o
>>   obj-$(CONFIG_STM32_WATCHDOG) += stm32_iwdg.o
>> diff --git a/drivers/watchdog/rzn1_wdt.c b/drivers/watchdog/rzn1_wdt.c
>> new file mode 100644
>> index 000000000000..fa32716727b7
>> --- /dev/null
>> +++ b/drivers/watchdog/rzn1_wdt.c
>> @@ -0,0 +1,203 @@
>> +// SPDX-License-Identifier: GPL-2.0
>> +/*
>> + * Renesas RZ/N1 Watchdog timer.
>> + * This is a 12-bit timer driver from a (62.5/16384) MHz clock. It 
>> can't even
>> + * cope with 2 seconds.
>> + *
>> + * Copyright 2018 Renesas Electronics Europe Ltd.
>> + *
>> + * Derived from Ralink RT288x watchdog timer.
>> + */
>> +
>> +#include <linux/clk.h>
>> +#include <linux/interrupt.h>
>> +#include <linux/kernel.h>
>> +#include <linux/module.h>
>> +#include <linux/of_address.h>
>> +#include <linux/of_irq.h>
>> +#include <linux/platform_device.h>
>> +#include <linux/reboot.h>
>> +#include <linux/watchdog.h>
>> +
>> +#define DEFAULT_TIMEOUT        60
>> +
>> +#define RZN1_WDT_RETRIGGER            0x0
>> +#define RZN1_WDT_RETRIGGER_RELOAD_VAL        0
>> +#define RZN1_WDT_RETRIGGER_RELOAD_VAL_MASK    0xfff
>> +#define RZN1_WDT_RETRIGGER_PRESCALE        BIT(12)
>> +#define RZN1_WDT_RETRIGGER_ENABLE        BIT(13)
>> +#define RZN1_WDT_RETRIGGER_WDSI            (0x2 << 14)
>> +
>> +#define RZN1_WDT_PRESCALER            16384
>> +#define RZN1_WDT_MAX                4095
>> +
>> +struct rzn1_watchdog {
>> +    struct watchdog_device        wdtdev;
>> +    void __iomem            *base;
>> +    unsigned long            clk_rate;
>
> Nit: Whenever clk_rate is used, it is divided by 1000.
> It might be better to store and use clk_rate_khz instead.

OK. I'll change this.

Thanks,

JJ

>
> Guenter