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Message-ID: <3da2f428-23de-659f-f508-7bb4cf65f2c1@starfivetech.com>
Date: Fri, 10 Mar 2023 10:25:33 +0800
From: Xingyu Wu <xingyu.wu@...rfivetech.com>
To: Emil Renner Berthing <emil.renner.berthing@...onical.com>
CC: <linux-riscv@...ts.infradead.org>, <devicetree@...r.kernel.org>,
<linux-watchdog@...r.kernel.org>,
Wim Van Sebroeck <wim@...ux-watchdog.org>,
Guenter Roeck <linux@...ck-us.net>,
Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
Emil Renner Berthing <kernel@...il.dk>,
Conor Dooley <conor@...nel.org>,
Rob Herring <robh+dt@...nel.org>,
"Paul Walmsley" <paul.walmsley@...ive.com>,
Palmer Dabbelt <palmer@...belt.com>,
Albert Ou <aou@...s.berkeley.edu>,
Philipp Zabel <p.zabel@...gutronix.de>,
Samin Guo <samin.guo@...rfivetech.com>,
<linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v4 2/3] drivers: watchdog: Add StarFive Watchdog driver
On 2023/3/9 21:46, Emil Renner Berthing wrote:
> On Thu, 9 Mar 2023 at 10:32, Xingyu Wu <xingyu.wu@...rfivetech.com> wrote:
>> On 2023/3/9 16:55, Emil Renner Berthing wrote:
>> > On Thu, 9 Mar 2023 at 08:08, Xingyu Wu <xingyu.wu@...rfivetech.com> wrote:
>> >> On 2023/3/8 23:07, Emil Renner Berthing wrote:
>> >> > On Wed, 8 Mar 2023 at 04:43, Xingyu Wu <xingyu.wu@...rfivetech.com> wrote:
>> >> >>
>> >> >> Add watchdog driver for the StarFive JH7100 and JH7110 SoC.
>> >> >>
>> >> >> Signed-off-by: Xingyu Wu <xingyu.wu@...rfivetech.com>
>> >> >
>> >> > Hi Xingyu,
>> >> >
>> >> > Thanks for adding the JH7100 support. I tried it on my Starlight board
>> >> > and it seems to work fine except systemd complains about not being
>> >> > able to set a 10min timeout on reboot:
>> >> > systemd-shutdown[1]: Using hardware watchdog 'StarFive Watchdog',
>> >> > version 0, device /dev/watchdog0
>> >> > systemd-shutdown[1]: Failed to set timeout to 10min: Invalid argument
>> >> > systemd-shutdown[1]: Syncing filesystems and block devices.
>> >> > systemd-shutdown[1]: Sending SIGTERM to remaining processes...
>> >> >
>> >> > The systemd runtime watchdog seems to work, so I guess this is just
>> >> > because 10min is too long a timeout for the StarFive watchdog.
>> >> >
>> >> > More comments below.
>> >>
>> >> Will fix.
>> >>
>> >> >
>> >> >> ---
>> >> >> MAINTAINERS | 7 +
>> >> >> drivers/watchdog/Kconfig | 9 +
>> >> >> drivers/watchdog/Makefile | 2 +
>> >> >> drivers/watchdog/starfive-wdt.c | 675 ++++++++++++++++++++++++++++++++
>> >> >> 4 files changed, 693 insertions(+)
>> >> >> create mode 100644 drivers/watchdog/starfive-wdt.c
>> >> >>
>> >> >> diff --git a/MAINTAINERS b/MAINTAINERS
>> >> >> index 8d5bc223f305..721d0e4e8a0d 100644
>> >> >> --- a/MAINTAINERS
>> >> >> +++ b/MAINTAINERS
>> >> >> @@ -19962,6 +19962,13 @@ S: Supported
>> >> >> F: Documentation/devicetree/bindings/rng/starfive*
>> >> >> F: drivers/char/hw_random/jh7110-trng.c
>> >> >>
>> >> >> +STARFIVE WATCHDOG DRIVER
>> >> >> +M: Xingyu Wu <xingyu.wu@...rfivetech.com>
>> >> >> +M: Samin Guo <samin.guo@...rfivetech.com>
>> >> >> +S: Supported
>> >> >> +F: Documentation/devicetree/bindings/watchdog/starfive*
>> >> >> +F: drivers/watchdog/starfive-wdt.c
>> >> >> +
>> >> >> STATIC BRANCH/CALL
>> >> >> M: Peter Zijlstra <peterz@...radead.org>
>> >> >> M: Josh Poimboeuf <jpoimboe@...nel.org>
>> >> >> diff --git a/drivers/watchdog/Kconfig b/drivers/watchdog/Kconfig
>> >> >> index f0872970daf9..9d825ffaf292 100644
>> >> >> --- a/drivers/watchdog/Kconfig
>> >> >> +++ b/drivers/watchdog/Kconfig
>> >> >> @@ -2090,6 +2090,15 @@ config UML_WATCHDOG
>> >> >> tristate "UML watchdog"
>> >> >> depends on UML || COMPILE_TEST
>> >> >>
>> >> >> +config STARFIVE_WATCHDOG
>> >> >> + tristate "StarFive Watchdog support"
>> >> >> + depends on ARCH_STARFIVE || COMPILE_TEST
>> >> >> + select WATCHDOG_CORE
>> >> >> + default ARCH_STARFIVE
>> >> >> + help
>> >> >> + Say Y here to support the watchdog of StarFive JH7100 and JH7110
>> >> >> + SoC. This driver can also be built as a module if choose M.
>> >> >
>> >> > This file seems to be sorted by architecture, so you probably want to
>> >> > add something like this at the appropriate place
>> >> >
>> >> > # RISC-V Architecture
>> >> >
>> >> > config STARFIVE_WATCHDOG
>> >> > ...
>> >> >
>> >>
>> >> Will add.
>> >>
>> >> >
>> >> >> #
>> >> >> # ISA-based Watchdog Cards
>> >> >> #
>> >> >> diff --git a/drivers/watchdog/Makefile b/drivers/watchdog/Makefile
>> >> >> index 9cbf6580f16c..4c0bd377e92a 100644
>> >> >> --- a/drivers/watchdog/Makefile
>> >> >> +++ b/drivers/watchdog/Makefile
>> >> >> @@ -211,6 +211,8 @@ obj-$(CONFIG_WATCHDOG_SUN4V) += sun4v_wdt.o
>> >> >> # Xen
>> >> >> obj-$(CONFIG_XEN_WDT) += xen_wdt.o
>> >> >>
>> >> >> +obj-$(CONFIG_STARFIVE_WATCHDOG) += starfive-wdt.o
>> >> >
>> >> > Again please follow the layout of the file. Eg. something like this at
>> >> > the appropriate place
>> >> >
>> >> > # RISC-V Architecture
>> >> > obj-$(CONFIG_STARFIVE_WATCHDOG) += starfive-wdt.o
>> >> >
>> >>
>> >> Will add.
>> >>
>> >> >> # Architecture Independent
>> >> >> obj-$(CONFIG_BD957XMUF_WATCHDOG) += bd9576_wdt.o
>> >> >> obj-$(CONFIG_DA9052_WATCHDOG) += da9052_wdt.o
>> >> >> diff --git a/drivers/watchdog/starfive-wdt.c b/drivers/watchdog/starfive-wdt.c
>> >> >> new file mode 100644
>> >> >> index 000000000000..8ce9f985f068
>> >> >> --- /dev/null
>> >> >> +++ b/drivers/watchdog/starfive-wdt.c
>> >> >> @@ -0,0 +1,675 @@
>> >> >> +// SPDX-License-Identifier: GPL-2.0
>> >> >> +/*
>> >> >> + * Starfive Watchdog driver
>> >> >> + *
>> >> >> + * Copyright (C) 2022 StarFive Technology Co., Ltd.
>> >> >> + */
>> >> >> +
>> >> >> +#include <linux/clk.h>
>> >> >> +#include <linux/iopoll.h>
>> >> >> +#include <linux/module.h>
>> >> >> +#include <linux/of_device.h>
>> >> >> +#include <linux/pm_runtime.h>
>> >> >> +#include <linux/reset.h>
>> >> >> +#include <linux/watchdog.h>
>> >> >> +
>> >> >> +/* JH7100 Watchdog register define */
>> >> >> +#define STARFIVE_WDT_JH7100_INTSTAUS 0x000 /* RO: [4]: Watchdog Interrupt status */
>> >> >> +#define STARFIVE_WDT_JH7100_CONTROL 0x104 /* RW: reset enable */
>> >> >> +#define STARFIVE_WDT_JH7100_LOAD 0x108 /* RW: Watchdog Load register */
>> >> >> +#define STARFIVE_WDT_JH7100_EN 0x110 /* RW: Watchdog Enable Register */
>> >> >> +#define STARFIVE_WDT_JH7100_RELOAD 0x114 /* RW: Write 0 or 1 to reload preset value */
>> >> >> +#define STARFIVE_WDT_JH7100_VALUE 0x118 /* RO: The current value for watchdog counter */
>> >> >> +#define STARFIVE_WDT_JH7100_INTCLR 0x120 /*
>> >> >> + * RW: Watchdog Clear Interrupt Register
>> >> >> + * [0]: Write 1 to clear interrupt
>> >> >> + * [1]: 1 mean clearing and 0 mean complete
>> >> >> + */
>> >> >> +#define STARFIVE_WDT_JH7100_LOCK 0x13c /* RW: Lock Register, write 0x378f0765 to unlock */
>> >> >> +
>> >> >> +/* JH7110 Watchdog register define */
>> >> >> +#define STARFIVE_WDT_JH7110_LOAD 0x000 /* RW: Watchdog Load register */
>> >> >> +#define STARFIVE_WDT_JH7110_VALUE 0x004 /* RO: The current value for watchdog counter */
>> >> >> +#define STARFIVE_WDT_JH7110_CONTROL 0x008 /*
>> >> >> + * RW:
>> >> >> + * [0]: reset enable;
>> >> >> + * [1]: int enable/wdt enable/reload counter;
>> >> >> + * [31:2]: reserved.
>> >> >> + */
>> >> >> +#define STARFIVE_WDT_JH7110_INTCLR 0x00c /* WO: clear intterupt && reload the counter */
>> >> >> +#define STARFIVE_WDT_JH7110_IMS 0x014 /* RO: Enabled interrupt status from the counter */
>> >> >> +#define STARFIVE_WDT_JH7110_LOCK 0xc00 /* RW: Lock Register, write 0x1ACCE551 to unlock */
>> >> >
>> >> > Since these register offsets are only used to fill in the
>> >> > starfive_wdt_variant structures, consider just adding them directly
>> >> > there with the comments.
>> >> >
>> >> >> +/* WDOGCONTROL */
>> >> >> +#define STARFIVE_WDT_ENABLE 0x1
>> >> >> +#define STARFIVE_WDT_EN_SHIFT 0
>> >> >> +#define STARFIVE_WDT_RESET_EN 0x1
>> >> >> +#define STARFIVE_WDT_JH7100_RESEN_SHIFT 0
>> >> >> +#define STARFIVE_WDT_JH7110_RESEN_SHIFT 1
>> >> >> +
>> >> >> +/* WDOGLOCK */
>> >> >> +#define STARFIVE_WDT_LOCKED BIT(0)
>> >> >> +#define STARFIVE_WDT_JH7100_UNLOCK_KEY 0x378f0765
>> >> >> +#define STARFIVE_WDT_JH7110_UNLOCK_KEY 0x1acce551
>> >> >> +
>> >> >> +/* WDOGINTCLR */
>> >> >> +#define STARFIVE_WDT_INTCLR 0x1
>> >> >> +#define STARFIVE_WDT_JH7100_INTCLR_AVA_SHIFT 1 /* Watchdog can clear interrupt when 0 */
>> >> >> +
>> >> >> +#define STARFIVE_WDT_MAXCNT 0xffffffff
>> >> >> +#define STARFIVE_WDT_DEFAULT_TIME (15)
>> >> >> +#define STARFIVE_WDT_DELAY_US 0
>> >> >> +#define STARFIVE_WDT_TIMEOUT_US 10000
>> >> >> +
>> >> >> +/* module parameter */
>> >> >> +#define STARFIVE_WDT_EARLY_ENA 0
>> >> >> +
>> >> >> +static bool nowayout = WATCHDOG_NOWAYOUT;
>> >> >> +static int heartbeat;
>> >> >> +static bool early_enable = STARFIVE_WDT_EARLY_ENA;
>> >> >> +
>> >> >> +module_param(heartbeat, int, 0);
>> >> >> +module_param(early_enable, bool, 0);
>> >> >> +module_param(nowayout, bool, 0);
>> >> >> +
>> >> >> +MODULE_PARM_DESC(heartbeat, "Watchdog heartbeat in seconds. (default="
>> >> >> + __MODULE_STRING(STARFIVE_WDT_DEFAULT_TIME) ")");
>> >> >> +MODULE_PARM_DESC(early_enable,
>> >> >> + "Watchdog is started at boot time if set to 1, default="
>> >> >> + __MODULE_STRING(STARFIVE_WDT_EARLY_ENA));
>> >> >> +MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="
>> >> >> + __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
>> >> >> +
>> >> >> +struct starfive_wdt_variant {
>> >> >> + /* resgister */
>> >> >> + unsigned int control;
>> >> >> + unsigned int load;
>> >> >> + unsigned int reload;
>> >> >> + unsigned int enable;
>> >> >> + unsigned int value;
>> >> >> + unsigned int int_clr;
>> >> >> + unsigned int unlock;
>> >> >> + unsigned int int_status;
>> >> >> +
>> >> >> + u32 unlock_key;
>> >> >> + u8 enrst_shift;
>> >> >> + u8 en_shift;
>> >> >> + bool intclr_check; /* whether need to check it before clearing interrupt */
>> >> >> + u8 intclr_ava_shift;
>> >> >
>> >> > The shifts here could just be char.
>> >>
>> >> Will fix.
>> >>
>> >> >
>> >> >> + bool double_timeout; /* The watchdog need twice timeout to reboot */
>> >> >> +};
>> >> >> +
>> >> >> +struct starfive_wdt {
>> >> >> + unsigned long freq;
>> >> >> + struct device *dev;
>> >> >
>> >> > This device pointer is also stored in the parent field of struct
>> >> > watchdog_device below, so not really needed.
>> >>
>> >> Will drop.
>> >>
>> >> >
>> >> >> + struct watchdog_device wdt_device;
>> >> >
>> >> > From looking at the other watchdog drivers a common name for this is just "wdd".
>> >>
>> >> Will modify it.
>> >>
>> >> >
>> >> >> + struct clk *core_clk;
>> >> >> + struct clk *apb_clk;
>> >> >> + struct reset_control *rsts;
>> >> >
>> >> > This pointer seems to be only used just after being obtained in the
>> >> > starfive_wdt_reset_init function, but never needed after that, so why
>> >> > store it here?
>> >>
>> >> Will modify it to be local variables.
>> >>
>> >> >
>> >> >> + u32 count; /*count of timeout*/
>> >> >> + u32 reload; /*restore the count*/
>> >> >
>> >> > Missing spaces between /*,*/ and text. Also please align with the comment below.
>> >>
>> >> Will fix.
>> >>
>> >> >
>> >> >> + void __iomem *base;
>> >> >> + spinlock_t lock; /* spinlock for register handling */
>> >> >> + const struct starfive_wdt_variant *drv_data;
>> >> >
>> >> > Hmm.. to me "driver data" is this struct, whereas this field points to
>> >> > SoC data. You already call the struct "variant", so why not just
>> >>
>> >> Will modify it.
>> >>
>> >> >
>> >> > const struct starfive_wdt_variant *variant;
>> >> >
>> >> >> +};
>> >> >
>> >> > Consider sorting fields by size to avoid too many alignment induced
>> >> > holes in the struct. Eg. something like
>> >> >
>> >> > struct starfive_wdt {
>> >> > struct watchdog_device wdd;
>> >> > spinlock_t lock;
>> >> > void __iomem *base;
>> >> > /* clock and reset pointers */
>> >> > const struct starfive_wdt_variant *variant;
>> >> > unsigned long freq;
>> >> > u32 count;
>> >> > u32 reload;
>> >> > };
>> >> >
>> >> > > +/* Register layout and configuration for the JH7100 */
>> >> >> +static const struct starfive_wdt_variant drv_data_jh7100 = {
>> >> >
>> >> > Please keep using the starfive_wdt_ prefix here. Eg. something like
>> >> >
>> >> > starfive_wdt_jh7100_variant and
>> >> > starfive_wdt_jh7110_variant
>> >>
>> >> Will modify it.
>> >>
>> >> >
>> >> >> + .control = STARFIVE_WDT_JH7100_CONTROL,
>> >> >> + .load = STARFIVE_WDT_JH7100_LOAD,
>> >> >> + .reload = STARFIVE_WDT_JH7100_RELOAD,
>> >> >> + .enable = STARFIVE_WDT_JH7100_EN,
>> >> >> + .value = STARFIVE_WDT_JH7100_VALUE,
>> >> >> + .int_clr = STARFIVE_WDT_JH7100_INTCLR,
>> >> >> + .unlock = STARFIVE_WDT_JH7100_LOCK,
>> >> >> + .unlock_key = STARFIVE_WDT_JH7100_UNLOCK_KEY,
>> >> >> + .int_status = STARFIVE_WDT_JH7100_INTSTAUS,
>> >> >> + .enrst_shift = STARFIVE_WDT_JH7100_RESEN_SHIFT,
>> >> >> + .en_shift = STARFIVE_WDT_EN_SHIFT,
>> >> >> + .intclr_check = true,
>> >> >> + .intclr_ava_shift = STARFIVE_WDT_JH7100_INTCLR_AVA_SHIFT,
>> >> >> + .double_timeout = false,
>> >> >> +};
>> >> >> +
>> >> >> +/* Register layout and configuration for the JH7110 */
>> >> >> +static const struct starfive_wdt_variant drv_data_jh7110 = {
>> >> >> + .control = STARFIVE_WDT_JH7110_CONTROL,
>> >> >> + .load = STARFIVE_WDT_JH7110_LOAD,
>> >> >> + .enable = STARFIVE_WDT_JH7110_CONTROL,
>> >> >> + .value = STARFIVE_WDT_JH7110_VALUE,
>> >> >> + .int_clr = STARFIVE_WDT_JH7110_INTCLR,
>> >> >> + .unlock = STARFIVE_WDT_JH7110_LOCK,
>> >> >> + .unlock_key = STARFIVE_WDT_JH7110_UNLOCK_KEY,
>> >> >> + .int_status = STARFIVE_WDT_JH7110_IMS,
>> >> >> + .enrst_shift = STARFIVE_WDT_JH7110_RESEN_SHIFT,
>> >> >> + .en_shift = STARFIVE_WDT_EN_SHIFT,
>> >> >> + .intclr_check = false,
>> >> >> + .double_timeout = true,
>> >> >> +};
>> >> >> +
>> >> >> +static const struct of_device_id starfive_wdt_match[] = {
>> >> >> + { .compatible = "starfive,jh7100-wdt", .data = &drv_data_jh7100 },
>> >> >> + { .compatible = "starfive,jh7110-wdt", .data = &drv_data_jh7110 },
>> >> >> + { /* sentinel */ }
>> >> >> +};
>> >> >> +MODULE_DEVICE_TABLE(of, starfive_wdt_match);
>> >> >
>> >> > Please move this struct just above struct platform_driver like most
>> >> > other drivers. It's nice to be able to open a driver, scroll to the
>> >> > bottom and immediately find the compatibles it matches on.
>> >>
>> >> Will move it.
>> >>
>> >> >
>> >> >> +static int starfive_wdt_get_clock_rate(struct starfive_wdt *wdt)
>> >> >> +{
>> >> >> + wdt->freq = clk_get_rate(wdt->core_clk);
>> >> >> + if (!wdt->freq) {
>> >> >> + dev_err(wdt->dev, "get clock rate failed.\n");
>> >> >> + return -EINVAL;
>> >> >> + }
>> >> >> +
>> >> >> + return 0;
>> >> >> +}
>> >> >
>> >> > This function seems a bit pointless since it's only used once in the
>> >> > probe function. Just inline it there. Consider doing the same for the
>> >> > functions getting clocks and resets.
>> >>
>> >> Will modify it.
>> >>
>> >> >
>> >> >> +static int starfive_wdt_enable_clock(struct starfive_wdt *wdt)
>> >> >> +{
>> >> >> + int ret;
>> >> >> +
>> >> >> + ret = clk_prepare_enable(wdt->apb_clk);
>> >> >> + if (ret)
>> >> >> + return dev_err_probe(wdt->dev, ret, "failed to enable apb_clk.\n");
>> >> >> +
>> >> >> + ret = clk_prepare_enable(wdt->core_clk);
>> >> >> + if (ret)
>> >> >> + return dev_err_probe(wdt->dev, ret, "failed to enable core_clk.\n");
>> >> >> +
>> >> >> + return 0;
>> >> >> +}
>> >> >> +
>> >> >> +static void starfive_wdt_disable_clock(struct starfive_wdt *wdt)
>> >> >> +{
>> >> >> + clk_disable_unprepare(wdt->core_clk);
>> >> >> + clk_disable_unprepare(wdt->apb_clk);
>> >> >> +}
>> >> >> +
>> >> >> +static int starfive_wdt_get_clock(struct starfive_wdt *wdt)
>> >> >> +{
>> >> >> + wdt->apb_clk = devm_clk_get(wdt->dev, "apb");
>> >> >> + if (IS_ERR(wdt->apb_clk))
>> >> >> + return dev_err_probe(wdt->dev, PTR_ERR(wdt->apb_clk),
>> >> >> + "failed to get apb clock.\n");
>> >> >> +
>> >> >> + wdt->core_clk = devm_clk_get(wdt->dev, "core");
>> >> >> + if (IS_ERR(wdt->core_clk))
>> >> >> + return dev_err_probe(wdt->dev, PTR_ERR(wdt->core_clk),
>> >> >> + "failed to get core clock.\n");
>> >> >> +
>> >> >> + return 0;
>> >> >> +}
>> >> >> +
>> >> >> +static int starfive_wdt_reset_init(struct starfive_wdt *wdt)
>> >> >> +{
>> >> >> + int ret;
>> >> >> +
>> >> >> + wdt->rsts = devm_reset_control_array_get_exclusive(wdt->dev);
>> >> >> + if (IS_ERR(wdt->rsts))
>> >> >> + return dev_err_probe(wdt->dev, PTR_ERR(wdt->rsts),
>> >> >> + "failed to get resets.\n");
>> >> >> +
>> >> >> + ret = reset_control_deassert(wdt->rsts);
>> >> >> + if (ret)
>> >> >> + return dev_err_probe(wdt->dev, ret,
>> >> >> + "failed to deassert resets.\n");
>> >> >> +
>> >> >> + return 0;
>> >> >> +}
>> >> >> +
>> >> >> +static u32 starfive_wdt_ticks_to_sec(struct starfive_wdt *wdt, u32 ticks)
>> >> >> +{
>> >> >> + return DIV_ROUND_CLOSEST(ticks, wdt->freq);
>> >> >> +}
>> >> >> +
>> >> >> +/*
>> >> >> + * Write unlock-key to unlock. Write other value to lock. When lock bit is 1,
>> >> >> + * external accesses to other watchdog registers are ignored.
>> >> >> + */
>> >> >> +static bool starfive_wdt_is_locked(struct starfive_wdt *wdt)
>> >> >> +{
>> >> >> + u32 val;
>> >> >> +
>> >> >> + val = readl(wdt->base + wdt->drv_data->unlock);
>> >> >
>> >> > u32 val = readl(...);
>> >> >
>> >> >> + return !!(val & STARFIVE_WDT_LOCKED);
>> >> >> +}
>> >> >> +
>> >> >> +static void starfive_wdt_unlock(struct starfive_wdt *wdt)
>> >> >> +{
>> >> >> + if (starfive_wdt_is_locked(wdt))
>> >> >> + writel(wdt->drv_data->unlock_key,
>> >> >> + wdt->base + wdt->drv_data->unlock);
>> >> >> +}
>> >> >> +
>> >> >> +static void starfive_wdt_lock(struct starfive_wdt *wdt)
>> >> >> +{
>> >> >> + if (!starfive_wdt_is_locked(wdt))
>> >> >> + writel(~wdt->drv_data->unlock_key,
>> >> >> + wdt->base + wdt->drv_data->unlock);
>> >> >> +}
>> >> >
>> >> > This looks suspicious. Is there really a situation where you
>> >> > legitimately need to operate on the registers in parallel or is this
>> >> > just glossing over programming errors? Shouldn't this
>> >> > locking/unlocking basically happen between taking the spinlock? If
>> >> > not, then doesn't this risk locking the registers while some other
>> >> > thread is still using them and expects them to be unlocked?
>> >>
>> >> This lock register enable write access to all other registers by writing
>> >> the unlock key. So if write registers should unlock this first. And I
>> >> usually unlock register with the spinlock first to confirm it not be used
>> >> repeatedly.
>> >
>> > Right, so if there is only one simultaneous user and you always lock
>> > the registers after use, there should be no need for the "if
>> > (starfive_wdt_is_locked(wdt))" checks. In fact you might even be able
>> > to fold the spinlock into these functions to make sure you always take
>> > the spinlock and unlock in the right order. Eg.:
>> >
>> > static void starfive_wdt_unlock(struct starfive_wdt *wdt)
>> > {
>> > spin_lock(&wdt->lock);
>> > writel(wdt->variant->unlock_key, wdt->base + wdt->variant->unlock);
>> > }
>> >
>> > static void starfive_wdt_lock(struct starfive_wdt *wdt)
>> > {
>> > writel(~wdt->variant->unlock_key, wdt->base + wdt->variant->unlock);
>> > spin_unlock(&wdt->lock);
>> > }
>> >
>>
>> Great. So, do I still need to check the status of the lock register before
>> locking or unlocking it?
>
> Yeah, that's what I'm asking you about. If you always
> - take the spinlock
> - unlock registers
> - modify registers
> - lock registers
> - release the spinlock
> ..in that order then I don't see why it should be necessary to check
> the status of the lock registers, since you'll know that the registers
> are always locked outside the spinlock. Perhaps you just need to check
> it once at probe time or reset the peripheral to fix the initial state
> of the watchdog.
>
Yeah, it is easy to control the lock status if check the status and write the
initail status at the beginning of the probe. But I had tested that it could be
unlocked by writing the unlock key whether it was locked or unlocked before.
Checking the status is less necessary and I prefer to drop it.
>> >> >
>> >> >> +/* enable watchdog interrupt to reset/reboot */
>> >> >> +static void starfive_wdt_enable_reset(struct starfive_wdt *wdt)
>> >> >> +{
>> >> >> + u32 val;
>> >> >> +
>> >> >> + val = readl(wdt->base + wdt->drv_data->control);
>> >> >> + val |= STARFIVE_WDT_RESET_EN << wdt->drv_data->enrst_shift;
>> >> >> + writel(val, wdt->base + wdt->drv_data->control);
>> >> >> +}
>> >> >> +
>> >> >> +/* interrupt status whether has been raised from the counter */
>> >> >> +static bool starfive_wdt_raise_irq_status(struct starfive_wdt *wdt)
>> >> >> +{
>> >> >> + return !!readl(wdt->base + wdt->drv_data->int_status);
>> >> >> +}
>> >> >> +
>> >> >> +/* waiting interrupt can be free to clear */
>> >> >> +static int starfive_wdt_wait_int_free(struct starfive_wdt *wdt)
>> >> >> +{
>> >> >> + u32 value;
>> >> >> +
>> >> >> + value = readl(wdt->base + wdt->drv_data->int_clr);
>> >> >
>> >> > Doesn't readl_poll_timeout_atomic below read the value before using
>> >> > it, so this line is redundant?
>> >>
>> >> Will drop it.
>> >>
>> >> >
>> >> >> + return readl_poll_timeout_atomic(wdt->base + wdt->drv_data->int_clr, value,
>> >> >> + !(value & BIT(wdt->drv_data->intclr_ava_shift)),
>> >> >> + STARFIVE_WDT_DELAY_US, STARFIVE_WDT_TIMEOUT_US);
>> >> >> +}
>> >> >> +
>> >> >> +/* clear interrupt signal before initialization or reload */
>> >> >> +static int starfive_wdt_int_clr(struct starfive_wdt *wdt)
>> >> >> +{
>> >> >> + int ret;
>> >> >> +
>> >> >> + if (wdt->drv_data->intclr_check) {
>> >> >> + ret = starfive_wdt_wait_int_free(wdt);
>> >> >> + if (ret)
>> >> >> + return dev_err_probe(wdt->dev, ret,
>> >> >> + "watchdog is not ready to clear interrupt.\n");
>> >> >> + }
>> >> >> + writel(STARFIVE_WDT_INTCLR, wdt->base + wdt->drv_data->int_clr);
>> >> >> +
>> >> >> + return 0;
>> >> >> +}
>> >> >> +
>> >> >> +static inline void starfive_wdt_set_count(struct starfive_wdt *wdt, u32 val)
>> >> >> +{
>> >> >> + writel(val, wdt->base + wdt->drv_data->load);
>> >> >> +}
>> >> >> +
>> >> >> +static inline u32 starfive_wdt_get_count(struct starfive_wdt *wdt)
>> >> >> +{
>> >> >> + return readl(wdt->base + wdt->drv_data->value);
>> >> >> +}
>> >> >> +
>> >> >> +/* enable watchdog */
>> >> >> +static inline void starfive_wdt_enable(struct starfive_wdt *wdt)
>> >> >> +{
>> >> >> + u32 val;
>> >> >> +
>> >> >> + val = readl(wdt->base + wdt->drv_data->enable);
>> >> >> + val |= STARFIVE_WDT_ENABLE << wdt->drv_data->en_shift;
>> >> >> + writel(val, wdt->base + wdt->drv_data->enable);
>> >> >> +}
>> >> >> +
>> >> >> +/* disable watchdog */
>> >> >> +static inline void starfive_wdt_disable(struct starfive_wdt *wdt)
>> >> >> +{
>> >> >> + u32 val;
>> >> >> +
>> >> >> + val = readl(wdt->base + wdt->drv_data->enable);
>> >> >> + val &= ~(STARFIVE_WDT_ENABLE << wdt->drv_data->en_shift);
>> >> >> + writel(val, wdt->base + wdt->drv_data->enable);
>> >> >> +}
>> >> >> +
>> >> >> +static inline void starfive_wdt_set_reload_count(struct starfive_wdt *wdt, u32 count)
>> >> >> +{
>> >> >> + starfive_wdt_set_count(wdt, count);
>> >> >> +
>> >> >> + /* 7100 need set any value to reload register and could reload value to counter */
>> >> >> + if (wdt->drv_data->reload)
>> >> >> + writel(0x1, wdt->base + wdt->drv_data->reload);
>> >> >> +}
>> >> >> +
>> >> >> +static unsigned int starfive_wdt_max_timeout(struct starfive_wdt *wdt)
>> >> >> +{
>> >> >> + unsigned int timeout_num = wdt->drv_data->double_timeout ? 2 : 1;
>> >> >> +
>> >> >> + return DIV_ROUND_UP(STARFIVE_WDT_MAXCNT, (wdt->freq / timeout_num)) - 1;
>> >> >> +}
>> >> >> +
>> >> >> +static unsigned int starfive_wdt_get_timeleft(struct watchdog_device *wdd)
>> >> >> +{
>> >> >> + struct starfive_wdt *wdt = watchdog_get_drvdata(wdd);
>> >> >> + u32 count;
>> >> >> +
>> >> >> + starfive_wdt_unlock(wdt);
>> >> >> + /*
>> >> >> + * If the watchdog takes twice timeout and set half count value,
>> >> >> + * timeleft value should add the count value before first timeout.
>> >> >> + */
>> >> >> + count = starfive_wdt_get_count(wdt);
>> >> >> + if (wdt->drv_data->double_timeout && !starfive_wdt_raise_irq_status(wdt))
>> >> >> + count += wdt->count;
>> >> >> +
>> >> >> + starfive_wdt_lock(wdt);
>> >> >> +
>> >> >> + return starfive_wdt_ticks_to_sec(wdt, count);
>> >> >> +}
>> >> >> +
>> >> >> +static int starfive_wdt_keepalive(struct watchdog_device *wdd)
>> >> >> +{
>> >> >> + struct starfive_wdt *wdt = watchdog_get_drvdata(wdd);
>> >> >> + int ret;
>> >> >> +
>> >> >> + spin_lock(&wdt->lock);
>> >> >> +
>> >> >> + starfive_wdt_unlock(wdt);
>> >> >> + ret = starfive_wdt_int_clr(wdt);
>> >> >> + if (ret)
>> >> >> + return ret;
>> >> >> +
>> >> >> + starfive_wdt_set_reload_count(wdt, wdt->count);
>> >> >> + starfive_wdt_lock(wdt);
>> >> >> +
>> >> >> + spin_unlock(&wdt->lock);
>> >> >> +
>> >> >> + return 0;
>> >> >> +}
>> >> >> +
>> >> >> +static int starfive_wdt_stop(struct watchdog_device *wdd)
>> >> >> +{
>> >> >> + struct starfive_wdt *wdt = watchdog_get_drvdata(wdd);
>> >> >> +
>> >> >> + spin_lock(&wdt->lock);
>> >> >> +
>> >> >> + starfive_wdt_unlock(wdt);
>> >> >> + starfive_wdt_disable(wdt);
>> >> >> + starfive_wdt_lock(wdt);
>> >> >> +
>> >> >> + spin_unlock(&wdt->lock);
>> >> >> +
>> >> >> + return 0;
>> >> >> +}
>> >> >> +
>> >> >> +static int starfive_wdt_pm_stop(struct watchdog_device *wdd)
>> >> >> +{
>> >> >> + struct starfive_wdt *wdt = watchdog_get_drvdata(wdd);
>> >> >> +
>> >> >> + starfive_wdt_stop(wdd);
>> >> >> + pm_runtime_put_sync(wdt->dev);
>> >> >> +
>> >> >> + return 0;
>> >> >> +}
>> >> >> +
>> >> >> +static int starfive_wdt_start(struct watchdog_device *wdd)
>> >> >> +{
>> >> >> + struct starfive_wdt *wdt = watchdog_get_drvdata(wdd);
>> >> >> + int ret;
>> >> >> +
>> >> >> + spin_lock(&wdt->lock);
>> >> >> + starfive_wdt_unlock(wdt);
>> >> >> + /* disable watchdog, to be safe */
>> >> >> + starfive_wdt_disable(wdt);
>> >> >> +
>> >> >> + starfive_wdt_enable_reset(wdt);
>> >> >> + ret = starfive_wdt_int_clr(wdt);
>> >> >> + if (ret)
>> >> >> + return ret;
>> >> >> +
>> >> >> + starfive_wdt_set_count(wdt, wdt->count);
>> >> >> + starfive_wdt_enable(wdt);
>> >> >> +
>> >> >> + starfive_wdt_lock(wdt);
>> >> >> + spin_unlock(&wdt->lock);
>> >> >> +
>> >> >> + return 0;
>> >> >> +}
>> >> >> +
>> >> >> +static int starfive_wdt_pm_start(struct watchdog_device *wdd)
>> >> >> +{
>> >> >> + struct starfive_wdt *wdt = watchdog_get_drvdata(wdd);
>> >> >> +
>> >> >> + pm_runtime_get_sync(wdt->dev);
>> >> >> +
>> >> >> + return starfive_wdt_start(wdd);
>> >> >> +}
>> >> >> +
>> >> >> +static int starfive_wdt_set_timeout(struct watchdog_device *wdd,
>> >> >> + unsigned int timeout)
>> >> >> +{
>> >> >> + struct starfive_wdt *wdt = watchdog_get_drvdata(wdd);
>> >> >> + unsigned long freq = wdt->freq;
>> >> >> + unsigned int timeout_num = wdt->drv_data->double_timeout ? 2 : 1;
>> >> >> +
>> >> >> + spin_lock(&wdt->lock);
>> >> >> +
>> >> >> + /*
>> >> >> + * This watchdog takes twice timeouts to reset.
>> >> >> + * In order to reduce time to reset, should set half count value.
>> >> >> + */
>> >> >> + wdt->count = timeout * freq / timeout_num;
>> >> >> + wdd->timeout = timeout;
>> >> >> + starfive_wdt_unlock(wdt);
>> >> >> + starfive_wdt_disable(wdt);
>> >> >> + starfive_wdt_set_reload_count(wdt, wdt->count);
>> >> >> + starfive_wdt_enable(wdt);
>> >> >> + starfive_wdt_lock(wdt);
>> >> >> +
>> >> >> + spin_unlock(&wdt->lock);
>> >> >> +
>> >> >> + return 0;
>> >> >> +}
>> >> >> +
>> >> >> +#define OPTIONS (WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE)
>> >> >
>> >> > This macro needs a much less generic name but it's only used below, so
>> >> > just set the .options directly there.
>> >>
>> >> Will use STARFIVE_OPTIONS instead.
>> >
>> > If you insist on defining this macro please keep the STARFIVE_WDT_
>> > prefix for consistency.
>>
>> Will fix.
>>
>> >
>> >> >
>> >> >> +static const struct watchdog_info starfive_wdt_ident = {
>> >> >
>> >> > Why invent a new name for this struct and not just follow the watchdog
>> >> > framework and call it starfive_wdt_info?
>> >>
>> >> Will fix.
>> >>
>> >> >
>> >> >> + .options = OPTIONS,
>> >> >> + .identity = "StarFive Watchdog",
>> >> >> +};
>> >> >> +
>> >> >> +static const struct watchdog_ops starfive_wdt_ops = {
>> >> >> + .owner = THIS_MODULE,
>> >> >> + .start = starfive_wdt_pm_start,
>> >> >> + .stop = starfive_wdt_pm_stop,
>> >> >> + .ping = starfive_wdt_keepalive,
>> >> >> + .set_timeout = starfive_wdt_set_timeout,
>> >> >> + .get_timeleft = starfive_wdt_get_timeleft,
>> >> >> +};
>> >> >> +
>> >> >> +static const struct watchdog_device starfive_wdd = {
>> >> >> + .info = &starfive_wdt_ident,
>> >> >> + .ops = &starfive_wdt_ops,
>> >> >> + .timeout = STARFIVE_WDT_DEFAULT_TIME,
>> >> >> +};
>> >> >> +
>> >> >> +static int starfive_wdt_probe(struct platform_device *pdev)
>> >> >> +{
>> >> >> + struct device *dev = &pdev->dev;
>> >> >> + struct starfive_wdt *wdt;
>> >> >> + int ret;
>> >> >> +
>> >> >> + wdt = devm_kzalloc(dev, sizeof(*wdt), GFP_KERNEL);
>> >> >> + if (!wdt)
>> >> >> + return -ENOMEM;
>> >> >> +
>> >> >> + wdt->dev = dev;
>> >> >> + spin_lock_init(&wdt->lock);
>> >> >> + wdt->wdt_device = starfive_wdd;
>> >> >
>> >> > This is a very elaborate way of setting 2 pointers and a timeout. Maybe just
>> >> >
>> >> > wdt->wdd.info = &starfive_wdt_info;
>> >> > wdt->wdd.ops = &starfive_wdt_ops;
>> >> >
>> >> > ..and drop the static const copy above. You already set the default
>> >> > timeout again below.
>> >>
>> >> Oh, got it. Will fix.
>> >>
>> >> >
>> >> >> + wdt->drv_data = of_device_get_match_data(&pdev->dev);
>> >> >> +
>> >> >> + /* get the memory region for the watchdog timer */
>> >> >> + wdt->base = devm_platform_ioremap_resource(pdev, 0);
>> >> >> + if (IS_ERR(wdt->base)) {
>> >> >> + ret = PTR_ERR(wdt->base);
>> >> >> + return ret;
>> >> >> + }
>> >> >> +
>> >> >> + platform_set_drvdata(pdev, wdt);
>> >> >> + pm_runtime_enable(wdt->dev);
>> >> >> +
>> >> >> + ret = starfive_wdt_get_clock(wdt);
>> >> >> + if (ret)
>> >> >> + return ret;
>> >> >> +
>> >> >> + if (pm_runtime_enabled(wdt->dev)) {
>> >> >> + ret = pm_runtime_get_sync(wdt->dev);
>> >> >> + if (ret < 0)
>> >> >> + return ret;
>> >> >> + } else {
>> >> >> + /* runtime PM is disabled but clocks need to be enabled */
>> >> >> + ret = starfive_wdt_enable_clock(wdt);
>> >> >> + if (ret)
>> >> >> + return ret;
>> >> >> + }
>> >> >> +
>> >> >> + ret = starfive_wdt_get_clock_rate(wdt);
>> >> >> + if (ret)
>> >> >> + goto err_exit;
>> >> >> +
>> >> >> + ret = starfive_wdt_reset_init(wdt);
>> >> >> + if (ret)
>> >> >> + goto err_exit;
>> >> >> +
>> >> >> + wdt->wdt_device.min_timeout = 1;
>> >> >> + wdt->wdt_device.max_timeout = starfive_wdt_max_timeout(wdt);
>> >> >> +
>> >> >> + watchdog_set_drvdata(&wdt->wdt_device, wdt);
>> >> >> +
>> >> >> + wdt->wdt_device.timeout = STARFIVE_WDT_DEFAULT_TIME;
>> >> >> + watchdog_init_timeout(&wdt->wdt_device, heartbeat, dev);
>> >> >> + starfive_wdt_set_timeout(&wdt->wdt_device, wdt->wdt_device.timeout);
>> >> >> +
>> >> >> + watchdog_set_nowayout(&wdt->wdt_device, nowayout);
>> >> >> + watchdog_stop_on_reboot(&wdt->wdt_device);
>> >> >> + watchdog_stop_on_unregister(&wdt->wdt_device);
>> >> >> +
>> >> >> + wdt->wdt_device.parent = dev;
>> >> >
>> >> > This can be set when you first initialise wdt->wdd.
>> >>
>> >> Will move.
>> >>
>> >> >
>> >> >> + if (early_enable) {
>> >> >> + starfive_wdt_start(&wdt->wdt_device);
>> >> >> + set_bit(WDOG_HW_RUNNING, &wdt->wdt_device.status);
>> >> >> + } else {
>> >> >> + starfive_wdt_stop(&wdt->wdt_device);
>> >> >> + }
>> >> >> +
>> >> >> + ret = watchdog_register_device(&wdt->wdt_device);
>> >> >> + if (ret)
>> >> >> + goto err_exit;
>> >> >> +
>> >> >> + if (!early_enable)
>> >> >> + pm_runtime_put_sync(wdt->dev);
>> >> >> +
>> >> >> + return 0;
>> >> >> +
>> >> >> +err_exit:
>> >> >> + starfive_wdt_disable_clock(wdt);
>> >> >> + pm_runtime_disable(wdt->dev);
>> >> >> +
>> >> >> + return ret;
>> >> >> +}
>> >> >> +
>> >> >> +static int starfive_wdt_remove(struct platform_device *dev)
>> >> >> +{
>> >> >> + struct starfive_wdt *wdt = platform_get_drvdata(dev);
>> >> >> +
>> >> >> + starfive_wdt_stop(&wdt->wdt_device);
>> >> >> + watchdog_unregister_device(&wdt->wdt_device);
>> >> >> +
>> >> >> + if (pm_runtime_enabled(wdt->dev))
>> >> >> + pm_runtime_disable(wdt->dev);
>> >> >> + else
>> >> >> + /* disable clock without PM */
>> >> >> + starfive_wdt_disable_clock(wdt);
>> >> >> +
>> >> >> + return 0;
>> >> >> +}
>> >> >> +
>> >> >> +static void starfive_wdt_shutdown(struct platform_device *dev)
>> >> >> +{
>> >> >> + struct starfive_wdt *wdt = platform_get_drvdata(dev);
>> >> >> +
>> >> >> + starfive_wdt_pm_stop(&wdt->wdt_device);
>> >> >> +}
>> >> >> +
>> >> >> +#ifdef CONFIG_PM_SLEEP
>> >> >> +static int starfive_wdt_suspend(struct device *dev)
>> >> >> +{
>> >> >> + int ret;
>> >> >> + struct starfive_wdt *wdt = dev_get_drvdata(dev);
>> >> >
>> >> > Please swap these around so initialised local variables come first.
>> >> > Also other places.
>> >>
>> >> Will fix.
>> >>
>> >> >
>> >> >> + starfive_wdt_unlock(wdt);
>> >> >> +
>> >> >> + /* Save watchdog state, and turn it off. */
>> >> >> + wdt->reload = starfive_wdt_get_count(wdt);
>> >> >> +
>> >> >> + /* Note that WTCNT doesn't need to be saved. */
>> >> >> + starfive_wdt_stop(&wdt->wdt_device);
>> >> >> + pm_runtime_force_suspend(dev);
>> >> >> +
>> >> >> + starfive_wdt_lock(wdt);
>> >> >> +
>> >> >> + return 0;
>> >> >> +}
>> >> >> +
>> >> >> +static int starfive_wdt_resume(struct device *dev)
>> >> >> +{
>> >> >> + int ret;
>> >> >> + struct starfive_wdt *wdt = dev_get_drvdata(dev);
>> >> >> +
>> >> >> + starfive_wdt_unlock(wdt);
>> >> >> +
>> >> >> + pm_runtime_force_resume(dev);
>> >> >> +
>> >> >> + /* Restore watchdog state. */
>> >> >> + starfive_wdt_set_reload_count(wdt, wdt->reload);
>> >> >> +
>> >> >> + starfive_wdt_start(&wdt->wdt_device);
>> >> >> +
>> >> >> + starfive_wdt_lock(wdt);
>> >> >> +
>> >> >> + return 0;
>> >> >> +}
>> >> >> +#endif /* CONFIG_PM_SLEEP */
>> >> >> +
>> >> >> +#ifdef CONFIG_PM
>> >> >> +static int starfive_wdt_runtime_suspend(struct device *dev)
>> >> >> +{
>> >> >> + struct starfive_wdt *wdt = dev_get_drvdata(dev);
>> >> >> +
>> >> >> + starfive_wdt_disable_clock(wdt);
>> >> >> +
>> >> >> + return 0;
>> >> >> +}
>> >> >> +
>> >> >> +static int starfive_wdt_runtime_resume(struct device *dev)
>> >> >> +{
>> >> >> + struct starfive_wdt *wdt = dev_get_drvdata(dev);
>> >> >> +
>> >> >> + return starfive_wdt_enable_clock(wdt);
>> >> >> +}
>> >> >> +#endif /* CONFIG_PM */
>> >> >> +
>> >> >> +static const struct dev_pm_ops starfive_wdt_pm_ops = {
>> >> >> + SET_RUNTIME_PM_OPS(starfive_wdt_runtime_suspend, starfive_wdt_runtime_resume, NULL)
>> >> >> + SET_SYSTEM_SLEEP_PM_OPS(starfive_wdt_suspend, starfive_wdt_resume)
>> >> >> +};
>> >> >> +
>> >> >> +static struct platform_driver starfive_wdt_driver = {
>> >> >> + .probe = starfive_wdt_probe,
>> >> >> + .remove = starfive_wdt_remove,
>> >> >> + .shutdown = starfive_wdt_shutdown,
>> >> >> + .driver = {
>> >> >> + .name = "starfive-wdt",
>> >> >> + .pm = &starfive_wdt_pm_ops,
>> >> >> + .of_match_table = of_match_ptr(starfive_wdt_match),
>> >> >> + },
>> >> >> +};
>> >> >> +
>> >> > This empty line not needed.
>> >> >> +module_platform_driver(starfive_wdt_driver);
>> >> >> +
>> >> >> +MODULE_AUTHOR("Xingyu Wu <xingyu.wu@...rfivetech.com>");
>> >> >> +MODULE_AUTHOR("Samin Guo <samin.guo@...rfivetech.com>");
>> >> >> +MODULE_DESCRIPTION("StarFive Watchdog Device Driver");
>> >> >> +MODULE_LICENSE("GPL");
>> >> >> --
>> >> >> 2.25.1
>> >> >>
>> >> >>
>> >> >> _______________________________________________
>> >> >> linux-riscv mailing list
>> >> >> linux-riscv@...ts.infradead.org
>> >> >> http://lists.infradead.org/mailman/listinfo/linux-riscv
>>
>> Best regards,
>> Xingyu Wu
>>
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