Re: [PATCH 2/8] usb: dwc3: core: Access XHCI address space temporarily to read port info

[Thinh Nguyen]

On Fri, Mar 10, 2023, Krishna Kurapati wrote:
> Currently host-only capable DWC3 controllers support Multiport. Temporarily
> map XHCI address space for host-only controllers and parse XHCI Extended
> Capabilities registers to read number of physical usb ports connected to the
> multiport controller (presuming each port is at least HS capable) and extract
> info on how many of these ports are Super Speed capable.
> 
> Signed-off-by: Krishna Kurapati <quic_kriskura@xxxxxxxxxxx>
> ---
>  drivers/usb/dwc3/core.c | 75 +++++++++++++++++++++++++++++++++++++++++
>  drivers/usb/dwc3/core.h |  9 +++++
>  2 files changed, 84 insertions(+)
> 
> diff --git a/drivers/usb/dwc3/core.c b/drivers/usb/dwc3/core.c
> index 476b63618511..076c0f8a4441 100644
> --- a/drivers/usb/dwc3/core.c
> +++ b/drivers/usb/dwc3/core.c
> @@ -37,6 +37,7 @@
>  #include "core.h"
>  #include "gadget.h"
>  #include "io.h"
> +#include "../host/xhci.h"

I think better to duplicate some of the logic in dwc3 driver and avoid
any direct dependency with the xhci driver.

>  
>  #include "debug.h"
>  
> @@ -1750,6 +1751,65 @@ static struct extcon_dev *dwc3_get_extcon(struct dwc3 *dwc)
>  	return edev;
>  }
>  
> +static int dwc3_read_port_info(struct dwc3 *dwc, struct resource *res)
> +{
> +	void __iomem		*regs;
> +	struct resource         dwc_res;
> +	u32			offset;
> +	u32			temp;
> +	u8			major_revision;
> +	int			ret = 0;
> +
> +	/*
> +	 * Remap xHCI address space to access XHCI ext cap regs,
> +	 * since it is needed to get port info.
> +	 */
> +	dwc_res = *res;
> +	dwc_res.start += 0;
> +	dwc_res.end = dwc->xhci_resources[0].start +
> +				DWC3_XHCI_REGS_END;

Isn't dwc->xhci_resources[0] already setup at this point? Can we use
dwc->xhci_resources[0] directly without copy the setting in dwc_res?

> +
> +	regs = ioremap(dwc_res.start, resource_size(&dwc_res));
> +	if (IS_ERR(regs))
> +		return PTR_ERR(regs);
> +
> +	offset = xhci_find_next_ext_cap(regs, 0,
> +					XHCI_EXT_CAPS_PROTOCOL);
> +	while (offset) {
> +		temp = readl(regs + offset);
> +		major_revision = XHCI_EXT_PORT_MAJOR(temp);
> +
> +		temp = readl(regs + offset + 0x08);
> +		if (major_revision == 0x03) {
> +			dwc->num_ss_ports += XHCI_EXT_PORT_COUNT(temp);
> +		} else if (major_revision <= 0x02) {
> +			dwc->num_ports += XHCI_EXT_PORT_COUNT(temp);
> +		} else {
> +			dev_err(dwc->dev, "port revision seems wrong\n");
> +			ret = -EINVAL;
> +			goto unmap_reg;
> +		}
> +
> +		offset = xhci_find_next_ext_cap(regs, offset,
> +						XHCI_EXT_CAPS_PROTOCOL);
> +	}
> +
> +	temp = readl(regs + DWC3_XHCI_HCSPARAMS1);
> +	if (HCS_MAX_PORTS(temp) != (dwc->num_ss_ports + dwc->num_ports)) {
> +		dev_err(dwc->dev, "inconsistency in port info\n");
> +		ret = -EINVAL;
> +		goto unmap_reg;
> +	}
> +
> +	dev_info(dwc->dev,
> +		"num-ports: %d ss-capable: %d\n", dwc->num_ports, dwc->num_ss_ports);

The end user doesn't need to know this info. This should be a debug
message. Perhaps it can be a tracepoint if needed?

> +
> +unmap_reg:
> +	iounmap(regs);
> +	return ret;
> +}
> +
>  static int dwc3_probe(struct platform_device *pdev)
>  {
>  	struct device		*dev = &pdev->dev;
> @@ -1757,6 +1817,7 @@ static int dwc3_probe(struct platform_device *pdev)
>  	struct dwc3		*dwc;
>  
>  	int			ret;
> +	unsigned int		hw_mode;
>  
>  	void __iomem		*regs;
>  
> @@ -1880,6 +1941,20 @@ static int dwc3_probe(struct platform_device *pdev)
>  			goto disable_clks;
>  	}
>  
> +	/*
> +	 * Currently DWC3 controllers that are host-only capable
> +	 * support Multiport.
> +	 */
> +	hw_mode = DWC3_GHWPARAMS0_MODE(dwc->hwparams.hwparams0);
> +	if (hw_mode == DWC3_GHWPARAMS0_MODE_HOST) {
> +		ret = dwc3_read_port_info(dwc, res);
> +		if (ret)
> +			goto disable_clks;
> +	} else {
> +		dwc->num_ports = 1;
> +		dwc->num_ss_ports = 1;
> +	}
> +
>  	spin_lock_init(&dwc->lock);
>  	mutex_init(&dwc->mutex);
>  
> diff --git a/drivers/usb/dwc3/core.h b/drivers/usb/dwc3/core.h
> index 582ebd9cf9c2..74386d6a0277 100644
> --- a/drivers/usb/dwc3/core.h
> +++ b/drivers/usb/dwc3/core.h
> @@ -35,6 +35,9 @@
>  
>  #define DWC3_MSG_MAX	500
>  
> +/* XHCI Reg constants */
> +#define DWC3_XHCI_HCSPARAMS1	0x04
> +
>  /* Global constants */
>  #define DWC3_PULL_UP_TIMEOUT	500	/* ms */
>  #define DWC3_BOUNCE_SIZE	1024	/* size of a superspeed bulk */
> @@ -1023,6 +1026,10 @@ struct dwc3_scratchpad_array {
>   * @usb_psy: pointer to power supply interface.
>   * @usb2_phy: pointer to USB2 PHY
>   * @usb3_phy: pointer to USB3 PHY
> + * @num_ports: Indicates the number of physical USB ports present on HW
> + *		presuming each port is at least HS capable

This isn't the number of physical USB ports right? That's the number of
usb2 ports the controller is configured with right?. Perhaps we can use
num_usb2_ports and num_usb3_ports?

> + * @num_ss_ports: Indicates the number of USB ports present on HW that are
> + *		SS Capable
>   * @usb2_generic_phy: pointer to USB2 PHY
>   * @usb3_generic_phy: pointer to USB3 PHY
>   * @phys_ready: flag to indicate that PHYs are ready
> @@ -1158,6 +1165,8 @@ struct dwc3 {
>  	struct usb_phy		*usb2_phy;
>  	struct usb_phy		*usb3_phy;
>  
> +	u32			num_ports;
> +	u32			num_ss_ports;
>  	struct phy		*usb2_generic_phy;
>  	struct phy		*usb3_generic_phy;
>  
> -- 
> 2.39.0
> 

Thanks,
Thinh