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watchdog: aspeed: add support for dual boot

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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 accessible 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>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Link: https://lore.kernel.org/r/20190828102402.13155-4-i.mikhaylov@yadro.com
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Wim Van Sebroeck <wim@linux-watchdog.org>
This commit is contained in:
Ivan Mikhaylov 2019-08-28 13:24:01 +03:00 committed by Wim Van Sebroeck
parent e07a4c79ca
commit 3d9e89bda9
1 changed files with 64 additions and 1 deletions
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65
drivers/watchdog/aspeed_wdt.c
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@ -54,6 +54,8 @@ 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
@ -166,6 +168,60 @@ 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)
{
struct aspeed_wdt *wdt = dev_get_drvdata(dev);
u32 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;
}
/*
* This attribute exists only if the system has booted from the alternate
* flash with 'alt-boot' option.
*
* At alternate flash 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.
*
* This option can be used with wdt2 (watchdog1) only.
*/
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,
@ -308,9 +364,16 @@ 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;
}
dev_set_drvdata(dev, wdt);
return devm_watchdog_register_device(dev, &wdt->wdd);
}