From: Guenter Roeck <linux@roeck-us.net>
To: Ivan Mikhaylov <i.mikhaylov@yadro.com>,
Wim Van Sebroeck <wim@linux-watchdog.org>
Cc: Joel Stanley <joel@jms.id.au>, Andrew Jeffery <andrew@aj.id.au>,
linux-watchdog@vger.kernel.org,
linux-arm-kernel@lists.infradead.org,
linux-aspeed@lists.ozlabs.org, linux-kernel@vger.kernel.org,
Alexander Amelkin <a.amelkin@yadro.com>,
openbmc@lists.ozlabs.org, Rob Herring <robh+dt@kernel.org>,
Mark Rutland <mark.rutland@arm.com>,
devicetree@vger.kernel.org
Subject: Re: [PATCH v2 3/4] watchdog/aspeed: add support for dual boot
Date: Mon, 26 Aug 2019 17:14:27 -0700 [thread overview]
Message-ID: <0df27d36-b45f-2059-6ead-a09ceb4b7605@roeck-us.net> (raw)
In-Reply-To: <20190826104636.19324-4-i.mikhaylov@yadro.com>
On 8/26/19 3:46 AM, Ivan Mikhaylov wrote:
> Set WDT_CLEAR_TIMEOUT_AND_BOOT_CODE_SELECTION into WDT_CLEAR_TIMEOUT_STATUS
> to clear out boot code source and re-enable access to the primary SPI flash
> chip while booted via wdt2 from the alternate chip.
>
> AST2400 datasheet says:
> "In the 2nd flash booting mode, all the address mapping to CS0# would be
> re-directed to CS1#. And CS0# is not accessable under this mode. To access
> CS0#, firmware should clear the 2nd boot mode register in the WDT2 status
> register WDT30.bit[1]."
>
> Signed-off-by: Ivan Mikhaylov <i.mikhaylov@yadro.com>
> ---
> drivers/watchdog/aspeed_wdt.c | 62 ++++++++++++++++++++++++++++++++++-
> 1 file changed, 61 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/watchdog/aspeed_wdt.c b/drivers/watchdog/aspeed_wdt.c
> index cc71861e033a..bbc42847c0e3 100644
> --- a/drivers/watchdog/aspeed_wdt.c
> +++ b/drivers/watchdog/aspeed_wdt.c
> @@ -53,6 +53,8 @@ MODULE_DEVICE_TABLE(of, aspeed_wdt_of_table);
> #define WDT_CTRL_ENABLE BIT(0)
> #define WDT_TIMEOUT_STATUS 0x10
> #define WDT_TIMEOUT_STATUS_BOOT_SECONDARY BIT(1)
> +#define WDT_CLEAR_TIMEOUT_STATUS 0x14
> +#define WDT_CLEAR_TIMEOUT_AND_BOOT_CODE_SELECTION BIT(0)
>
> /*
> * WDT_RESET_WIDTH controls the characteristics of the external pulse (if
> @@ -165,6 +167,57 @@ static int aspeed_wdt_restart(struct watchdog_device *wdd,
> return 0;
> }
>
> +/* 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)
This and other multi-line declarations do not appear to be aligned
with '('.
> +{
> + struct aspeed_wdt *wdt = dev_get_drvdata(dev);
> + uint32_t status = readl(wdt->base + WDT_TIMEOUT_STATUS);
> +
> + return sprintf(buf, "%u\n",
> + !(status & WDT_TIMEOUT_STATUS_BOOT_SECONDARY));
> +}
> +
> +static ssize_t access_cs0_store(struct device *dev,
> + struct device_attribute *attr,
> + const char *buf, size_t size)
> +{
> + struct aspeed_wdt *wdt = dev_get_drvdata(dev);
> + unsigned long val;
> +
> + if (kstrtoul(buf, 10, &val))
> + return -EINVAL;
> +
> + if (val)
> + writel(WDT_CLEAR_TIMEOUT_AND_BOOT_CODE_SELECTION,
> + wdt->base + WDT_CLEAR_TIMEOUT_STATUS);
> +
> + return size;
> +}
> +
> +/*
> + * At alternate side the 'access_cs0' sysfs node provides:
> + * ast2400: a way to get access to the primary SPI flash chip at CS0
> + * after booting from the alternate chip at CS1.
> + * ast2500: a way to restore the normal address mapping from
> + * (CS0->CS1, CS1->CS0) to (CS0->CS0, CS1->CS1).
> + *
> + * Clearing the boot code selection and timeout counter also resets to the
> + * initial state the chip select line mapping. When the SoC is in normal
> + * mapping state (i.e. booted from CS0), clearing those bits does nothing for
> + * both versions of the SoC. For alternate boot mode (booted from CS1 due to
> + * wdt2 expiration) the behavior differs as described above.
> + *
The above needs to be in the sysfs attribute documentation as well.
> + * This option can be used with wdt2 (watchdog1) only.
This implies a specific watchdog numbering which is not guaranteed.
Someone might implement a system with some external watchdog.
> + */
> +static DEVICE_ATTR_RW(access_cs0);
> +
> +static struct attribute *bswitch_attrs[] = {
> + &dev_attr_access_cs0.attr,
> + NULL
> +};
> +ATTRIBUTE_GROUPS(bswitch);
> +
> static const struct watchdog_ops aspeed_wdt_ops = {
> .start = aspeed_wdt_start,
> .stop = aspeed_wdt_stop,
> @@ -306,9 +359,16 @@ static int aspeed_wdt_probe(struct platform_device *pdev)
> }
>
> status = readl(wdt->base + WDT_TIMEOUT_STATUS);
> - if (status & WDT_TIMEOUT_STATUS_BOOT_SECONDARY)
> + 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;
Kind of odd that the attribute only exists if the system booted from the
second flash, but if that is what you want I won't object. Just make sure
that this is explained properly.
> + }
> +
> + dev_set_drvdata(dev, wdt);
> +
> return devm_watchdog_register_device(dev, &wdt->wdd);
> }
>
>
next prev parent reply other threads:[~2019-08-27 0:14 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-08-26 10:46 [PATCH v2 0/4] add dual-boot support Ivan Mikhaylov
2019-08-26 10:46 ` [PATCH v2 1/4] vesnin: add wdt2 section with alt-boot option Ivan Mikhaylov
2019-08-26 10:46 ` [PATCH v2 2/4] vesnin: add secondary SPI flash chip Ivan Mikhaylov
2019-08-26 10:46 ` [PATCH v2 3/4] watchdog/aspeed: add support for dual boot Ivan Mikhaylov
2019-08-27 0:14 ` Guenter Roeck [this message]
2019-08-27 9:24 ` Ivan Mikhaylov
2019-08-27 13:06 ` Guenter Roeck
2019-08-26 10:46 ` [PATCH v2 4/4] dt-bindings/watchdog: Add access_cs0 option for alt-boot Ivan Mikhaylov
2019-08-26 23:57 ` Andrew Jeffery
2019-08-27 0:08 ` Guenter Roeck
2019-08-27 0:11 ` Andrew Jeffery
2019-08-29 22:56 ` Rob Herring
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