linux-kernel - [PATCH 2/4] usb: uhci: Add reset control support

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Message-ID: <20250915073926.3057368-3-ryan_chen@aspeedtech.com>
Date: Mon, 15 Sep 2025 15:39:24 +0800
From: Ryan Chen <ryan_chen@...eedtech.com>
To: ryan_chen <ryan_chen@...eedtech.com>, Greg Kroah-Hartman
	<gregkh@...uxfoundation.org>, Rob Herring <robh@...nel.org>, "Krzysztof
 Kozlowski" <krzk+dt@...nel.org>, Conor Dooley <conor+dt@...nel.org>, "Alan
 Stern" <stern@...land.harvard.edu>, Philipp Zabel <p.zabel@...gutronix.de>,
	<linux-usb@...r.kernel.org>, <devicetree@...r.kernel.org>,
	<linux-kernel@...r.kernel.org>
Subject: [PATCH 2/4] usb: uhci: Add reset control support

Some SoCs, such as the Aspeed AST2700, require the UHCI controller
to be taken out of reset before it can operate. Add optional reset
control support to the UHCI platform driver.

The driver now acquires an optional reset line from device tree,
deasserts it during probe, and asserts it again in the error path
and shutdown.

Signed-off-by: Ryan Chen <ryan_chen@...eedtech.com>
---
 drivers/usb/host/uhci-hcd.h      |  1 +
 drivers/usb/host/uhci-platform.c | 19 +++++++++++++++++--
 2 files changed, 18 insertions(+), 2 deletions(-)

diff --git a/drivers/usb/host/uhci-hcd.h b/drivers/usb/host/uhci-hcd.h
index 13ee2a6144b2..4326d1f3ca76 100644
--- a/drivers/usb/host/uhci-hcd.h
+++ b/drivers/usb/host/uhci-hcd.h
@@ -445,6 +445,7 @@ struct uhci_hcd {
 	short load[MAX_PHASE];			/* Periodic allocations */
 
 	struct clk *clk;			/* (optional) clock source */
+	struct reset_control *rsts;		/* (optional) clock reset */
 
 	/* Reset host controller */
 	void	(*reset_hc) (struct uhci_hcd *uhci);
diff --git a/drivers/usb/host/uhci-platform.c b/drivers/usb/host/uhci-platform.c
index 62318291f566..010c458e7d8f 100644
--- a/drivers/usb/host/uhci-platform.c
+++ b/drivers/usb/host/uhci-platform.c
@@ -11,6 +11,7 @@
 #include <linux/of.h>
 #include <linux/device.h>
 #include <linux/platform_device.h>
+#include <linux/reset.h>
 
 static int uhci_platform_init(struct usb_hcd *hcd)
 {
@@ -132,19 +133,33 @@ static int uhci_hcd_platform_probe(struct platform_device *pdev)
 		goto err_rmr;
 	}
 
+	uhci->rsts = devm_reset_control_array_get_optional_shared(&pdev->dev);
+	if (IS_ERR(uhci->rsts)) {
+		ret = PTR_ERR(uhci->rsts);
+		goto err_clk;
+	}
+	ret = reset_control_deassert(uhci->rsts);
+	if (ret)
+		goto err_clk;
+
 	ret = platform_get_irq(pdev, 0);
 	if (ret < 0)
-		goto err_clk;
+		goto err_reset;
 
 	ret = usb_add_hcd(hcd, ret, IRQF_SHARED);
 	if (ret)
-		goto err_clk;
+		goto err_reset;
 
 	device_wakeup_enable(hcd->self.controller);
 	return 0;
 
 err_clk:
 	clk_disable_unprepare(uhci->clk);
+
+err_reset:
+	if (!IS_ERR_OR_NULL(uhci->rsts))
+		reset_control_assert(uhci->rsts);
+
 err_rmr:
 	usb_put_hcd(hcd);
 
-- 
2.34.1