Re: [PATCH] usb: gadget: udc-xilinx: Add clock support

[Felipe Balbi <balbi@kernel.org>]

Hi,

Shubhrajyoti Datta <shubhrajyoti.datta@xilinx.com> writes:
> Currently the driver depends on the  bootloader to enable the clocks.
> Add support for clocking. The patch enables the clock at  probe and
> disables them at remove.
>
> Signed-off-by: Shubhrajyoti Datta <shubhrajyoti.datta@xilinx.com>
> ---
>  drivers/usb/gadget/udc/udc-xilinx.c | 24 ++++++++++++++++++++++++
>  1 file changed, 24 insertions(+)
>
> diff --git a/drivers/usb/gadget/udc/udc-xilinx.c b/drivers/usb/gadget/udc/udc-xilinx.c
> index fb4ffedd6f0d..30070a488c87 100644
> --- a/drivers/usb/gadget/udc/udc-xilinx.c
> +++ b/drivers/usb/gadget/udc/udc-xilinx.c
> @@ -11,6 +11,7 @@
>   * USB peripheral controller (at91_udc.c).
>   */
>  
> +#include <linux/clk.h>
>  #include <linux/delay.h>
>  #include <linux/device.h>
>  #include <linux/dma-mapping.h>
> @@ -171,6 +172,7 @@ struct xusb_ep {
>   * @addr: the usb device base address
>   * @lock: instance of spinlock
>   * @dma_enabled: flag indicating whether the dma is included in the system
> + * @clk: pointer to struct clk
>   * @read_fn: function pointer to read device registers
>   * @write_fn: function pointer to write to device registers
>   */
> @@ -188,6 +190,7 @@ struct xusb_udc {
>  	void __iomem *addr;
>  	spinlock_t lock;
>  	bool dma_enabled;
> +	struct clk *clk;
>  
>  	unsigned int (*read_fn)(void __iomem *);
>  	void (*write_fn)(void __iomem *, u32, u32);
> @@ -2092,6 +2095,26 @@ static int xudc_probe(struct platform_device *pdev)
>  	udc->gadget.ep0 = &udc->ep[XUSB_EP_NUMBER_ZERO].ep_usb;
>  	udc->gadget.name = driver_name;
>  
> +	udc->clk = devm_clk_get(&pdev->dev, "s_axi_aclk");
> +	if (IS_ERR(udc->clk)) {
> +		if (PTR_ERR(udc->clk) != -ENOENT) {
> +			ret = PTR_ERR(udc->clk);
> +			goto fail;
> +		}
> +
> +		/*
> +		 * Clock framework support is optional, continue on,
> +		 * anyways if we don't find a matching clock
> +		 */
> +		udc->clk = NULL;

should it be, though? Might be a good idea to add fixed-clock instances
to the boards still depending on clock framework. Maybe that can be done
over time, but worth considering anyhow.

-- 
balbi