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Message-ID: <787d7a81-0f53-4dbb-b8d6-f7b00e9cf837@roeck-us.net>
Date: Fri, 1 Nov 2024 15:16:39 -0700
From: Guenter Roeck <linux@...ck-us.net>
To: Chin-Ting Kuo <chin-ting_kuo@...eedtech.com>, patrick@...cx.xyz,
joel@....id.au, andrew@...econstruct.com.au, wim@...ux-watchdog.org,
linux-arm-kernel@...ts.infradead.org, linux-aspeed@...ts.ozlabs.org,
linux-kernel@...r.kernel.org, linux-watchdog@...r.kernel.org
Cc: Peter.Yin@...ntatw.com, Patrick_NC_Lin@...ynn.com, Bonnie_Lo@...ynn.com,
DELPHINE_CHIU@...ynn.com, bmc-sw@...eedtech.com, chnguyen@...erecomputing.com
Subject: Re: [PATCH v4 1/3] watchdog: aspeed: Update bootstatus handling
On 11/1/24 05:11, Chin-Ting Kuo wrote:
> The boot status in the watchdog device struct is updated during
> controller probe stage. Application layer can get the boot status
> through the command, cat /sys/class/watchdog/watchdogX/bootstatus.
>
> The boot status mapping rule follows the latest design guide from
> the OpenBMC shown as below.
> https://github.com/openbmc/docs/blob/master/designs/bmc-reboot-cause-update.md#proposed-design
> - WDIOF_EXTERN1 => system is reset by Software
> - WDIOF_CARDRESET => system is reset by WDT SoC reset
> - Others => other reset events, e.g., power on reset.
>
> On ASPEED platform, the boot status is recorded in the SCU registers.
> - AST2400: Only a bit represents for any WDT reset.
> - AST2500: The reset triggered by different WDT controllers can be
> distinguished by different SCU bits. But, WDIOF_EXTERN1 or
> WDIOF_CARDRESET still cannot be identified due to
> HW limitation.
> - AST2600: Different from AST2500, additional HW bits are added for
> distinguishing WDIOF_EXTERN1 and WDIOF_CARDRESET.
>
> Besides, since alternating boot event is triggered by WDT SoC reset,
> it is classified as WDIOF_CARDRESET.
>
> Signed-off-by: Chin-Ting Kuo <chin-ting_kuo@...eedtech.com>
> ---
> drivers/watchdog/aspeed_wdt.c | 83 ++++++++++++++++++++++++++++++++++-
> 1 file changed, 81 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/watchdog/aspeed_wdt.c b/drivers/watchdog/aspeed_wdt.c
> index b4773a6aaf8c..4ad6335ff25b 100644
> --- a/drivers/watchdog/aspeed_wdt.c
> +++ b/drivers/watchdog/aspeed_wdt.c
> @@ -11,21 +11,31 @@
> #include <linux/io.h>
> #include <linux/kernel.h>
> #include <linux/kstrtox.h>
> +#include <linux/mfd/syscon.h>
> #include <linux/module.h>
> #include <linux/of.h>
> #include <linux/of_irq.h>
> #include <linux/platform_device.h>
> +#include <linux/regmap.h>
> #include <linux/watchdog.h>
>
> static bool nowayout = WATCHDOG_NOWAYOUT;
> module_param(nowayout, bool, 0);
> MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="
> __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
> +struct aspeed_wdt_scu {
> + const char *compatible;
> + u32 reset_status_reg;
> + u32 wdt_reset_mask;
> + u32 wdt_sw_reset_mask;
> + u32 wdt_reset_mask_shift;
> +};
>
> struct aspeed_wdt_config {
> u32 ext_pulse_width_mask;
> u32 irq_shift;
> u32 irq_mask;
> + struct aspeed_wdt_scu scu;
> };
>
> struct aspeed_wdt {
> @@ -39,18 +49,39 @@ static const struct aspeed_wdt_config ast2400_config = {
> .ext_pulse_width_mask = 0xff,
> .irq_shift = 0,
> .irq_mask = 0,
> + .scu = {
> + .compatible = "aspeed,ast2400-scu",
> + .reset_status_reg = 0x3c,
> + .wdt_reset_mask = 0x1,
> + .wdt_sw_reset_mask = 0,
> + .wdt_reset_mask_shift = 1,
> + },
> };
>
> static const struct aspeed_wdt_config ast2500_config = {
> .ext_pulse_width_mask = 0xfffff,
> .irq_shift = 12,
> .irq_mask = GENMASK(31, 12),
> + .scu = {
> + .compatible = "aspeed,ast2500-scu",
> + .reset_status_reg = 0x3c,
> + .wdt_reset_mask = 0x1,
> + .wdt_sw_reset_mask = 0,
> + .wdt_reset_mask_shift = 2,
> + },
> };
>
> static const struct aspeed_wdt_config ast2600_config = {
> .ext_pulse_width_mask = 0xfffff,
> .irq_shift = 0,
> .irq_mask = GENMASK(31, 10),
> + .scu = {
> + .compatible = "aspeed,ast2600-scu",
> + .reset_status_reg = 0x74,
> + .wdt_reset_mask = 0xf,
> + .wdt_sw_reset_mask = 0x8,
> + .wdt_reset_mask_shift = 16,
> + },
> };
>
> static const struct of_device_id aspeed_wdt_of_table[] = {
> @@ -213,6 +244,52 @@ static int aspeed_wdt_restart(struct watchdog_device *wdd,
> return 0;
> }
>
> +static int aspeed_wdt_update_bootstatus(struct platform_device *pdev,
> + struct aspeed_wdt *wdt)
> +{
> + struct resource *res;
> + struct aspeed_wdt_scu scu = wdt->cfg->scu;
> + struct regmap *scu_base;
> + u32 reset_mask_width;
> + u32 reset_mask_shift;
> + u32 reg_size = 0;
Please no unnecesary initializations.
> + u32 idx = 0;
> + u32 status;
> + int ret;
> +
> + res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> + reg_size = res->end - res->start;
> +
> + if (reg_size != 0)
> + idx = ((intptr_t)wdt->base & 0x00000fff) / reg_size;
> +
> + /* On ast2400, only a bit is used to represent WDT reset */
> + if (of_device_is_compatible(pdev->dev.of_node, "aspeed,ast2400-wdt"))
> + idx = 0;
> +
There is some redundancy in the above code, and platform_get_resource()
can return NULL. If idx==0 for aspeed,ast2400-wdt anyway, the code can be
rewritten as
if (!of_device_is_compatible(pdev->dev.of_node, "aspeed,ast2400-wdt")) {
res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
if (res) {
reg_size = res->end - res->start;
if (reg_size)
idx = ((intptr_t)wdt->base & 0x00000fff) / reg_size;
}
}
> + scu_base = syscon_regmap_lookup_by_compatible(scu.compatible);
> + if (IS_ERR(scu_base))
> + return PTR_ERR(scu_base);
> +
> + ret = regmap_read(scu_base, scu.reset_status_reg, &status);
> + if (ret)
> + return ret;
The above only affects bootstatus. Why fail to load the driver just because
bootstatus can not be read ?
> +
> + reset_mask_width = hweight32(scu.wdt_reset_mask);
> + reset_mask_shift = scu.wdt_reset_mask_shift +
> + reset_mask_width * idx;
> +
> + if (status & (scu.wdt_sw_reset_mask << reset_mask_shift))
> + wdt->wdd.bootstatus = WDIOF_EXTERN1;
> + else if (status & (scu.wdt_reset_mask << reset_mask_shift))
> + wdt->wdd.bootstatus = WDIOF_CARDRESET;
> + else
> + wdt->wdd.bootstatus = 0;
That is already 0.
> +
> + return regmap_write(scu_base, scu.reset_status_reg,
> + scu.wdt_reset_mask << reset_mask_shift);
> +}
> +
> /* access_cs0 shows if cs0 is accessible, hence the reverted bit */
> static ssize_t access_cs0_show(struct device *dev,
> struct device_attribute *attr, char *buf)
> @@ -458,10 +535,12 @@ static int aspeed_wdt_probe(struct platform_device *pdev)
> writel(duration - 1, wdt->base + WDT_RESET_WIDTH);
> }
>
> + ret = aspeed_wdt_update_bootstatus(pdev, wdt);
> + if (ret)
> + return ret;
> +
> status = readl(wdt->base + WDT_TIMEOUT_STATUS);
> if (status & WDT_TIMEOUT_STATUS_BOOT_SECONDARY) {
> - wdt->wdd.bootstatus = WDIOF_CARDRESET;
> -
> if (of_device_is_compatible(np, "aspeed,ast2400-wdt") ||
> of_device_is_compatible(np, "aspeed,ast2500-wdt"))
> wdt->wdd.groups = bswitch_groups;
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