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@aspeedtech.com>
---
 drivers/usb/host/uhci-hcd.h      |  1 +
 drivers/usb/host/uhci-platform.c | 18 ++++++++++++++++--
 2 files changed, 17 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..f255358d6242 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)
 {
@@ -132,17 +133,29 @@ 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_reset:
+	if (!IS_ERR_OR_NULL(uhci->rsts))
+		reset_control_assert(uhci->rsts);
 err_clk:
 	clk_disable_unprepare(uhci->clk);
 err_rmr:
@@ -156,6 +169,7 @@ static void uhci_hcd_platform_remove(struct platform_device *pdev)
 	struct usb_hcd *hcd = platform_get_drvdata(pdev);
 	struct uhci_hcd *uhci = hcd_to_uhci(hcd);
 
+	reset_control_assert(uhci->rsts);
 	clk_disable_unprepare(uhci->clk);
 	usb_remove_hcd(hcd);
 	usb_put_hcd(hcd);
-- 
2.34.1

On Fri, Sep 19, 2025 at 10:57:10AM +0800, Ryan Chen wrote:
> 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@aspeedtech.com>
> ---
>  drivers/usb/host/uhci-hcd.h      |  1 +
>  drivers/usb/host/uhci-platform.c | 18 ++++++++++++++++--
>  2 files changed, 17 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..f255358d6242 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)
>  {
> @@ -132,17 +133,29 @@ 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);

Does this work right if uhci->rsts is NULL?

> +	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_reset:
> +	if (!IS_ERR_OR_NULL(uhci->rsts))
> +		reset_control_assert(uhci->rsts);

How could this code ever execute if uhci->rsts is an ERR_PTR?

Also, why does this code test for NULL...

>  err_clk:
>  	clk_disable_unprepare(uhci->clk);
>  err_rmr:
> @@ -156,6 +169,7 @@ static void uhci_hcd_platform_remove(struct platform_device *pdev)
>  	struct usb_hcd *hcd = platform_get_drvdata(pdev);
>  	struct uhci_hcd *uhci = hcd_to_uhci(hcd);
>  
> +	reset_control_assert(uhci->rsts);

when this code doesn't?

Alan Stern

>  	clk_disable_unprepare(uhci->clk);
>  	usb_remove_hcd(hcd);
>  	usb_put_hcd(hcd);
> -- 
> 2.34.1
>