ath79: reset ETH switch for AR9344

According to datasheet, on AR9344 the switch and switch analog need to
be reset first before initiating a full reset.

Resetting these systems fixes spurious reset hangs on Atheros AR9344
SoCs.

Link: https://github.com/freifunk-gluon/gluon/issues/2904
Signed-off-by: David Bauer <mail@david-bauer.net>

diff --git a/target/linux/ath79/patches-6.6/101-reset-ath79-reset-ETH-switch-for-AR9344.patch b/target/linux/ath79/patches-6.6/101-reset-ath79-reset-ETH-switch-for-AR9344.patch
new file mode 100644 (file)
index 0000000..dcac5be
--- /dev/null
+++ b/target/linux/ath79/patches-6.6/101-reset-ath79-reset-ETH-switch-for-AR9344.patch
@@ -0,0 +1,104 @@
+From: David Bauer <mail@david-bauer.net>
+Date: Tue, 2 Jan 2025 19:22:40 +0100
+Subject: [PATCH] reset: ath79: reset ETH switch for AR9344
+
+According to datasheet, on AR9344 the switch and switch analog need to
+be reset first before initiating a full reset.
+
+Resetting these systems fixes spurious reset hangs on Atheros AR9344
+SoCs.
+
+Link: https://github.com/freifunk-gluon/gluon/issues/2904
+
+Signed-off-by: David Bauer <mail@david-bauer.net>
+
+--- a/drivers/reset/reset-ath79.c
++++ b/drivers/reset/reset-ath79.c
+@@ -12,8 +12,11 @@
+ #include <linux/platform_device.h>
+ #include <linux/reset-controller.h>
+ #include <linux/reboot.h>
++#include <linux/delay.h>
++#include <linux/of.h>
+ 
+ struct ath79_reset {
++      struct platform_device *pdev;
+       struct reset_controller_dev rcdev;
+       struct notifier_block restart_nb;
+       void __iomem *base;
+@@ -21,16 +24,13 @@ struct ath79_reset {
+ };
+ 
+ #define FULL_CHIP_RESET 24
++#define ETH_SWITCH_RESET 8
++#define ETH_SWITCH_ARESET 12
+ 
+-static int ath79_reset_update(struct reset_controller_dev *rcdev,
++static void __ath79_reset_update_unlocked(struct ath79_reset *ath79_reset,
+                       unsigned long id, bool assert)
+ {
+-      struct ath79_reset *ath79_reset =
+-              container_of(rcdev, struct ath79_reset, rcdev);
+-      unsigned long flags;
+       u32 val;
+-
+-      spin_lock_irqsave(&ath79_reset->lock, flags);
+       val = readl(ath79_reset->base);
+       if (assert)
+               val |= BIT(id);
+@@ -39,6 +39,17 @@ static int ath79_reset_update(struct res
+       writel(val, ath79_reset->base);
+       /* Flush cache */
+       readl(ath79_reset->base);
++}
++
++static int ath79_reset_update(struct reset_controller_dev *rcdev,
++                      unsigned long id, bool assert)
++{
++      struct ath79_reset *ath79_reset =
++              container_of(rcdev, struct ath79_reset, rcdev);
++      unsigned long flags;
++
++      spin_lock_irqsave(&ath79_reset->lock, flags);
++      __ath79_reset_update_unlocked(ath79_reset, id, assert);
+       spin_unlock_irqrestore(&ath79_reset->lock, flags);
+ 
+       return 0;
+@@ -79,8 +90,27 @@ static int ath79_reset_restart_handler(s
+ {
+       struct ath79_reset *ath79_reset =
+               container_of(nb, struct ath79_reset, restart_nb);
++      unsigned long flags;
+ 
+-      ath79_reset_assert(&ath79_reset->rcdev, FULL_CHIP_RESET);
++      spin_lock_irqsave(&ath79_reset->lock, flags);
++
++      if (of_device_is_compatible(ath79_reset->pdev->dev.of_node, "qca,ar9340-reset")) {
++              /**
++               * AR9344 has been observed to hang on reboot in rare cases.
++               *
++               * Datasheet states to reset the ETH switch systems before asserting
++               * full chip reset. See page 111 of the AR9344 datasheet.
++               */
++              __ath79_reset_update_unlocked(ath79_reset, ETH_SWITCH_RESET, true);
++              mdelay(10);
++              __ath79_reset_update_unlocked(ath79_reset, ETH_SWITCH_ARESET, true);
++              mdelay(10);
++      }
++
++      __ath79_reset_update_unlocked(ath79_reset, FULL_CHIP_RESET, true);
++      mdelay(10);
++
++      spin_unlock_irqrestore(&ath79_reset->lock, flags);
+ 
+       return NOTIFY_DONE;
+ }
+@@ -95,6 +125,8 @@ static int ath79_reset_probe(struct plat
+       if (!ath79_reset)
+               return -ENOMEM;
+ 
++      ath79_reset->pdev = pdev;
++
+       ath79_reset->base = devm_platform_ioremap_resource(pdev, 0);
+       if (IS_ERR(ath79_reset->base))
+               return PTR_ERR(ath79_reset->base);