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ath79: reset ETH switch for AR9344

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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>
(cherry picked from commit 916af73fc3)
This commit is contained in:
David Bauer 2025-01-03 21:46:13 +01:00
parent 50dcebeb8a
commit 0c52c9d6fc
1 changed files with 104 additions and 0 deletions
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104
target/linux/ath79/patches-6.6/101-reset-ath79-reset-ETH-switch-for-AR9344.patch Normal file
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@ -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);