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@xxxxxxxxx>
---
drivers/watchdog/aspeed_wdt.c | 65 ++++++++++++++++++++++++++++++++++-
1 file changed, 64 insertions(+), 1 deletion(-)
diff --git a/drivers/watchdog/aspeed_wdt.c b/drivers/watchdog/aspeed_wdt.c
index cc71861e033a..d27030d766ed 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 +167,60 @@ 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);
+ 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;
+}
+
+/*
+ * 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,
@@ -306,9 +362,16 @@ 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);
}
--
2.20.1
