On Fri, 12 Jan 2018, Benjamin Herrenschmidt wrote:
> The Aspeed SoCs use uhci-platform. With the new dynamic clock
> control framework, the corresponding IP block clock must be
> properly enabled.
>
> This is a simplified variant of what ehci-platform does, it
> looks for *one* clock attached to the device, and if it's
> there, enables it.
>
> Signed-off-by: Benjamin Herrenschmidt <b...@kernel.crashing.org>
> ---
>
> v2. Don't forget to git add latest changes :-) This adds the
> part where we turn the clock off when removing the driver.
>
> drivers/usb/host/uhci-hcd.h | 3 +++
> drivers/usb/host/uhci-platform.c | 18 ++++++++++++++++++
> 2 files changed, 21 insertions(+)
>
> diff --git a/drivers/usb/host/uhci-hcd.h b/drivers/usb/host/uhci-hcd.h
> index f1cc47292a59..7f9f33c8c232 100644
> --- a/drivers/usb/host/uhci-hcd.h
> +++ b/drivers/usb/host/uhci-hcd.h
> @@ -4,6 +4,7 @@
>
> #include <linux/list.h>
> #include <linux/usb.h>
> +#include <linux/clk.h>
>
> #define usb_packetid(pipe) (usb_pipein(pipe) ? USB_PID_IN : USB_PID_OUT)
> #define PIPE_DEVEP_MASK 0x0007ff00
> @@ -447,6 +448,8 @@ struct uhci_hcd {
> int total_load; /* Sum of array values */
> short load[MAX_PHASE]; /* Periodic allocations */
>
> + struct clk *clk; /* (optional) clock source */
> +
> /* Reset host controller */
> void (*reset_hc) (struct uhci_hcd *uhci);
> int (*check_and_reset_hc) (struct uhci_hcd *uhci);
> diff --git a/drivers/usb/host/uhci-platform.c
> b/drivers/usb/host/uhci-platform.c
> index 6cb16d4b2257..3d7da7338391 100644
> --- a/drivers/usb/host/uhci-platform.c
> +++ b/drivers/usb/host/uhci-platform.c
> @@ -119,6 +119,21 @@ static int uhci_hcd_platform_probe(struct
> platform_device *pdev)
> "Enabled Aspeed implementation workarounds\n");
> }
> }
> +
> + /* Get and enable clock if any specified */
> + uhci->clk = devm_clk_get(&pdev->dev, NULL);
> + if (IS_ERR(uhci->clk)) {
> + ret = PTR_ERR(uhci->clk);
> + goto err_rmr;
> + }
As Sergei mentioned, please be consistent in the use of tabs vs.
spaces.
Do you have to worry about EPROBE_DEFER errors at any point?
> + if (uhci->clk) {
> + ret = clk_prepare_enable(uhci->clk);
> + if (ret) {
> + dev_err(&pdev->dev, "Error couldn't enable clock
> (%d)\n", ret);
> + goto err_rmr;
> + }
> + }
> +
> ret = usb_add_hcd(hcd, pdev->resource[1].start, IRQF_SHARED);
> if (ret)
> goto err_rmr;
This error path needs to call clk_disable_unprepare.
> @@ -135,7 +150,10 @@ static int uhci_hcd_platform_probe(struct
> platform_device *pdev)
> static int uhci_hcd_platform_remove(struct platform_device *pdev)
> {
> struct usb_hcd *hcd = platform_get_drvdata(pdev);
> + struct uhci_hcd *uhci = hcd_to_uhci(hcd);
>
> + if (uhci->clk)
> + clk_disable_unprepare(uhci->clk);
> usb_remove_hcd(hcd);
> usb_put_hcd(hcd);
Alan Stern
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