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([2600:1700:e321:62f0:da43:aeff:fecc:bfd5]) by smtp.gmail.com with ESMTPSA id 41be03b00d2f7-b26eaf5c6bbsm8559327a12.6.2025.05.20.16.15.37 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 20 May 2025 16:15:38 -0700 (PDT) Sender: Guenter Roeck Message-ID: <38df2f02-efc4-465b-aa64-4c9e2c1919d8@roeck-us.net> Date: Tue, 20 May 2025 16:15:36 -0700 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v4 4/4] watchdog: Add support for VIA/WonderMedia SoC watchdog functionality To: Alexey Charkov , Krzysztof Kozlowski , Daniel Lezcano , Thomas Gleixner , Rob Herring , Conor Dooley , Krzysztof Kozlowski , Wim Van Sebroeck Cc: linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, devicetree@vger.kernel.org, linux-watchdog@vger.kernel.org References: <20250521-vt8500-timer-updates-v4-0-2d4306a16ae4@gmail.com> <20250521-vt8500-timer-updates-v4-4-2d4306a16ae4@gmail.com> Content-Language: en-US From: Guenter Roeck Autocrypt: addr=linux@roeck-us.net; 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charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 5/20/25 13:01, Alexey Charkov wrote: > VIA/WonderMedia SoCs can use their system timer's first channel as a > watchdog device which will reset the system if the clocksource counter > matches the value given in its match register 0 and if the watchdog > function is enabled. > > Since the watchdog function is tightly coupled to the timer itself, it > is implemented as an auxiliary device of the timer device > > Signed-off-by: Alexey Charkov > --- > MAINTAINERS | 1 + > drivers/watchdog/Kconfig | 15 ++++++++ > drivers/watchdog/Makefile | 1 + > drivers/watchdog/vt8500-wdt.c | 80 +++++++++++++++++++++++++++++++++++++++++++ > 4 files changed, 97 insertions(+) > > diff --git a/MAINTAINERS b/MAINTAINERS > index 5362095240627f613638197fda275db6edc16cf7..97d1842625dbdf7fdca3556260662dab469ed091 100644 > --- a/MAINTAINERS > +++ b/MAINTAINERS > @@ -3447,6 +3447,7 @@ F: drivers/tty/serial/vt8500_serial.c > F: drivers/video/fbdev/vt8500lcdfb.* > F: drivers/video/fbdev/wm8505fb* > F: drivers/video/fbdev/wmt_ge_rops.* > +F: drivers/watchdog/vt8500-wdt.c > F: include/linux/vt8500-timer.h > > ARM/ZYNQ ARCHITECTURE > diff --git a/drivers/watchdog/Kconfig b/drivers/watchdog/Kconfig > index 0d8d37f712e8cfb4bf8156853baa13c23a57d6d9..8049ae630301a98123f97f6e3ee868bd3bf1534a 100644 > --- a/drivers/watchdog/Kconfig > +++ b/drivers/watchdog/Kconfig > @@ -2003,6 +2003,21 @@ config PIC32_DMT > To compile this driver as a loadable module, choose M here. > The module will be called pic32-dmt. > > +config VT8500_WATCHDOG > + tristate "VIA/WonderMedia VT8500 watchdog support" > + depends on ARCH_VT8500 || COMPILE_TEST > + select WATCHDOG_CORE > + select AUXILIARY_BUS > + help > + VIA/WonderMedia SoCs can use their system timer as a hardware > + watchdog, as long as the first timer channel is free from other > + uses and respective function is enabled in its registers. To > + make use of it, say Y here and ensure that the device tree > + lists at least two interrupts for the VT8500 timer device. > + > + To compile this driver as a module, choose M here. > + The module will be called vt8500-wdt. > + > # PARISC Architecture > > # POWERPC Architecture > diff --git a/drivers/watchdog/Makefile b/drivers/watchdog/Makefile > index c9482904bf870a085c7fce2a439ac5089b6e6fee..3072786bf226c357102be3734fe6e701f753d45b 100644 > --- a/drivers/watchdog/Makefile > +++ b/drivers/watchdog/Makefile > @@ -101,6 +101,7 @@ obj-$(CONFIG_MSC313E_WATCHDOG) += msc313e_wdt.o > obj-$(CONFIG_APPLE_WATCHDOG) += apple_wdt.o > obj-$(CONFIG_SUNPLUS_WATCHDOG) += sunplus_wdt.o > obj-$(CONFIG_MARVELL_GTI_WDT) += marvell_gti_wdt.o > +obj-$(CONFIG_VT8500_WATCHDOG) += vt8500-wdt.o > > # X86 (i386 + ia64 + x86_64) Architecture > obj-$(CONFIG_ACQUIRE_WDT) += acquirewdt.o > diff --git a/drivers/watchdog/vt8500-wdt.c b/drivers/watchdog/vt8500-wdt.c > new file mode 100644 > index 0000000000000000000000000000000000000000..54fe5ad7695de36f6b3c1d28e955f00bef00e9db > --- /dev/null > +++ b/drivers/watchdog/vt8500-wdt.c > @@ -0,0 +1,80 @@ > +// SPDX-License-Identifier: GPL-2.0 > +/* Copyright (C) 2025 Alexey Charkov + > +#include > +#include > +#include > +#include > +#include > +#include > +#include > +#include > + > +static int vt8500_watchdog_start(struct watchdog_device *wdd) > +{ > + struct vt8500_wdt_info *info = watchdog_get_drvdata(wdd); > + u64 deadline = info->timer_next(wdd->timeout * VT8500_TIMER_HZ); > + wdd->timeout is the soft timeout, which may be larger than the maximum hardware timeout. That means you'll need to use something like "min(wdd->timeout, U32_MAX / VT8500_TIMER_HZ) * VT8500_TIMER_HZ" as parameter to the timer_next call. > + writel((u32)deadline, info->wdt_match); Can deadline overflow ? > + writel(TIMER_WD_EN, info->wdt_en); > + return 0; > +} > + > +static int vt8500_watchdog_stop(struct watchdog_device *wdd) > +{ > + struct vt8500_wdt_info *info = watchdog_get_drvdata(wdd); > + > + writel(0, info->wdt_en); > + return 0; > +} > + > +static const struct watchdog_ops vt8500_watchdog_ops = { > + .start = vt8500_watchdog_start, > + .stop = vt8500_watchdog_stop, > +}; > + > +static const struct watchdog_info vt8500_watchdog_info = { > + .identity = "VIA VT8500 watchdog", > + .options = WDIOF_MAGICCLOSE | > + WDIOF_KEEPALIVEPING | > + WDIOF_SETTIMEOUT, > +}; > + > +static int vt8500_wdt_probe(struct auxiliary_device *auxdev, > + const struct auxiliary_device_id *id) > +{ > + struct vt8500_wdt_info *info; > + struct watchdog_device *wdd; > + > + wdd = devm_kzalloc(&auxdev->dev, sizeof(*wdd), GFP_KERNEL); > + if (!wdd) > + return -ENOMEM; > + > + wdd->info = &vt8500_watchdog_info; > + wdd->ops = &vt8500_watchdog_ops; > + wdd->max_hw_heartbeat_ms = U32_MAX / (VT8500_TIMER_HZ / 1000); > + wdd->parent = &auxdev->dev; > + > + info = container_of(auxdev, struct vt8500_wdt_info, auxdev); > + watchdog_set_drvdata(wdd, info); > + > + return devm_watchdog_register_device(&auxdev->dev, wdd); > +} > + > +static const struct auxiliary_device_id vt8500_wdt_ids[] = { > + { .name = "timer_vt8500.vt8500-wdt" }, > + {}, > +}; > + > +MODULE_DEVICE_TABLE(auxiliary, my_auxiliary_id_table); > + > +static struct auxiliary_driver vt8500_wdt_driver = { > + .name = "vt8500-wdt", > + .probe = vt8500_wdt_probe, > + .id_table = vt8500_wdt_ids, > +}; > +module_auxiliary_driver(vt8500_wdt_driver); > + > +MODULE_AUTHOR("Alexey Charkov "); > +MODULE_DESCRIPTION("Driver for the VIA VT8500 watchdog timer"); > +MODULE_LICENSE("GPL"); >