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Date: Tue, 9 Jun 2020 16:57:50 +0800
From: Dilip Kota <eswara.kota@...ux.intel.com>
To: Guenter Roeck <linux@...ck-us.net>, wim@...ux-watchdog.org,
linux-watchdog@...r.kernel.org, devicetree@...r.kernel.org,
robbh@...nel.org
Cc: linux-kernel@...r.kernel.org, andriy.shevchenko@...el.com,
cheol.yong.kim@...el.com, qi-ming.wu@...el.com, yixin.zhu@...el.com
Subject: Re: [PATCH 2/2] watchdog: intel: Watchdog timer support on Lightning
Mountain
On 6/8/2020 9:36 PM, Guenter Roeck wrote:
> On 6/7/20 10:49 PM, Dilip Kota wrote:
>> On Intel Lightning Mountain SoC, General Purpose Timer Counter(GPTC)
>> programmable as clocksource, real time clock or watchdog timer.
>>
>> This driver configures GPTC as Watchdog timer and triggers reset signal
>> to CPU on timeout.
>>
>> Signed-off-by: Dilip Kota <eswara.kota@...ux.intel.com>
>> ---
>> drivers/watchdog/Kconfig | 13 ++
>> drivers/watchdog/Makefile | 1 +
>> drivers/watchdog/intel_lgm_gptc_wdt.c | 420 ++++++++++++++++++++++++++++++++++
>> 3 files changed, 434 insertions(+)
>> create mode 100644 drivers/watchdog/intel_lgm_gptc_wdt.c
>>
>> diff --git a/drivers/watchdog/Kconfig b/drivers/watchdog/Kconfig
>> index 0663c604bd642..8009c11e75dda 100644
>> --- a/drivers/watchdog/Kconfig
>> +++ b/drivers/watchdog/Kconfig
>> @@ -1789,6 +1789,19 @@ config IMGPDC_WDT
>> To compile this driver as a loadable module, choose M here.
>> The module will be called imgpdc_wdt.
>>
>> +config INTEL_LGM_GPTC_WDT
>> + tristate "INTEL LGM SoC Watchdog"
>> + depends on X86 || COMPILE_TEST
>> + depends on OF && HAS_IOMEM
>> + select REGMAP
>> + select MFD_SYSCON
>> + select WATCHDOG_CORE
>> + help
>> + Driver for Watchdog Timer on Intel Lightning Mountain SoC.
>> +
>> + To compile this driver as a loadable module, choose M here.
>> + The module will be called intel_lgm_gptc_wdt.
>> +
>> config LANTIQ_WDT
>> tristate "Lantiq SoC watchdog"
>> depends on LANTIQ
>> diff --git a/drivers/watchdog/Makefile b/drivers/watchdog/Makefile
>> index 6de2e4ceef190..92c99e4c46eb7 100644
>> --- a/drivers/watchdog/Makefile
>> +++ b/drivers/watchdog/Makefile
>> @@ -166,6 +166,7 @@ obj-$(CONFIG_TXX9_WDT) += txx9wdt.o
>> obj-$(CONFIG_OCTEON_WDT) += octeon-wdt.o
>> octeon-wdt-y := octeon-wdt-main.o octeon-wdt-nmi.o
>> obj-$(CONFIG_LANTIQ_WDT) += lantiq_wdt.o
>> +obj-$(CONFIG_INTEL_LGM_GPTC_WDT) += intel_lgm_gptc_wdt.o
>> obj-$(CONFIG_LOONGSON1_WDT) += loongson1_wdt.o
>> obj-$(CONFIG_RALINK_WDT) += rt2880_wdt.o
>> obj-$(CONFIG_IMGPDC_WDT) += imgpdc_wdt.o
>> diff --git a/drivers/watchdog/intel_lgm_gptc_wdt.c b/drivers/watchdog/intel_lgm_gptc_wdt.c
>> new file mode 100644
>> index 0000000000000..52be7cc194f8f
>> --- /dev/null
>> +++ b/drivers/watchdog/intel_lgm_gptc_wdt.c
>> @@ -0,0 +1,420 @@
>> +// SPDX-License-Identifier: GPL-2.0
>> +/*
>> + * Copyright (C) 2020 Intel Corporation.
>> + */
>> +
>> +#include <linux/bitfield.h>
>> +#include <linux/clk.h>
>> +#include <linux/cpu.h>
>> +#include <linux/io.h>
>> +#include <linux/kernel.h>
>> +#include <linux/mfd/syscon.h>
>> +#include <linux/module.h>
>> +#include <linux/of_device.h>
>> +#include <linux/platform_device.h>
>> +#include <linux/regmap.h>
>> +#include <linux/watchdog.h>
>> +
>> +#define GPTC_CLC 0x00
>> +#define GPTC_CLC_SUSPEND BIT(4)
>> +#define GPTC_CLC_RMC GENMASK(15, 8)
>> +
>> +/* divider 10 to produce 200 / 10 = 20 MHz clock */
>> +#define CLC_RMC_DIV 10
>> +
>> +#define GPTC_CON(X) (0x10 + (X) * 0x20)
>> +#define GPTC_CON_CNT_UP BIT(1)
>> +#define GPTC_CON_ONESHOT BIT(3)
>> +#define GPTC_CON_EXT BIT(4)
>> +
>> +#define GPTC_RUN(X) (0x18 + (X) * 0x20)
>> +#define GPTC_RUN_EN BIT(0)
>> +#define GPTC_RUN_STOP BIT(1)
>> +#define GPTC_RUN_RELOAD BIT(2)
>> +
>> +#define GPTC_RLD(X) (0x20 + (X) * 0x20)
>> +#define GPTC_CNT(X) (0x28 + (X) * 0x20)
>> +
>> +#define GPTC_IRNENCLR 0xF0
>> +#define GPTC_IRNEN 0xF4
>> +#define GPTC_IRNCR 0xFC
>> +
>> +/* Watchdog Timeout Reset register offset and bitfeilds */
>> +#define BIA_WDT_RST_EN 0x1E0
>> +#define BIA_WDT BIT(6)
>> +
>> +#define MAX_TIMERID 2
>> +#define MAX_CPUID 3
>> +#define TIMER_MARGIN_SEC 300
>> +
>> +static bool nowayout = WATCHDOG_NOWAYOUT;
>> +module_param(nowayout, bool, 0);
>> +MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started\n"
>> + " (default=" __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
>> +
>> +struct lgm_gptc_timer {
>> + struct lgm_gptc_wdt *wdt_node;
>> + struct watchdog_device wdd;
>> + unsigned int tid;
>> + unsigned int cpuid;
>> + unsigned int frequency;
>> + unsigned int cycles;
>> + bool enable;
>> +};
>> +
>> +struct lgm_gptc_wdt {
>> + struct device *dev;
>> + void __iomem *gptc_base;
>> + struct regmap *rst_hndl;
>> + struct clk *freqclk;
>> + struct clk *gateclk;
>> + unsigned int fpifreq;
>> + enum cpuhp_state state;
>> +};
>> +
>> +DEFINE_PER_CPU(struct lgm_gptc_timer, lgm_timer_per_cpu);
>> +
> This is unusual. You'll have to provide a very detailed explanation
> why this is needed.
Sure will add it.
It is required for the hotplug cpu support, and hotplug cpu is added
because, the cpus on Lightning Mountain SoC can be online and offline
dynamically.
If CPUs come to online after the watchdog driver probe, hotplug CPU
support helps to configure watchdog timer once CPU is online.
Regards,
-Dilip
>
> Guenter
>
>
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