Re: [PATCH v6 2/8] usb: dwc3: core: Access XHCI address space temporarily to read port info

[Thinh Nguyen]

On Wed, Apr 05, 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 usb2 ports and usb3 ports present on
> multiport controller. Each USB Port is atleast HS capable.
> 
> The port info for usb2 and usb3 phy are identified as num_usb2_ports and
> num_usb3_ports. The intention is as follows:
> 
> Wherever we need to perform phy operations like:
> 
> LOOP_OVER_NUMBER_OF_AVAILABLE_PORTS()
> {
> 	phy_set_mode(dwc->usb2_generic_phy[i], PHY_MODE_USB_HOST);
> 	phy_set_mode(dwc->usb3_generic_phy[i], PHY_MODE_USB_HOST);
> }
> 
> If number of usb2 ports is 3, loop can go from index 0-2 for usb2_generic_phy.
> If number of usb3-ports is 2, we don't know for sure, if the first 2 ports are
> SS capable or some other ports like (2 and 3) are SS capable. So instead,
> num_usb2_ports is used to loop around all phy's (both hs and ss) for
> performing phy operations. If any usb3_generic_phy turns out to be NULL, phy
> operation just bails out.
> 
> num_usb3_ports is used to modify GUSB3PIPECTL registers while setting up
> phy's as we need to know how many SS capable ports are there for this.
> 
> Signed-off-by: Krishna Kurapati <quic_kriskura@xxxxxxxxxxx>
> ---
> Link to v5: https://urldefense.com/v3/__https://lore.kernel.org/all/20230310163420.7582-3-quic_kriskura@xxxxxxxxxxx/__;!!A4F2R9G_pg!eXaKJejrT053M_6af46mC8jjyBmdZBBhJ0bVKlyxFiIMR_V1RwlBs_9VdvXhpJuNBDHi0d8kdZDrI0MdFKnKA6VA0i6Fww$ 
> 
>  drivers/usb/dwc3/core.c | 69 +++++++++++++++++++++++++++++++++++++++++
>  drivers/usb/dwc3/core.h | 60 +++++++++++++++++++++++++++++++++++
>  2 files changed, 129 insertions(+)
> 
> diff --git a/drivers/usb/dwc3/core.c b/drivers/usb/dwc3/core.c
> index 476b63618511..567ae79389a1 100644
> --- a/drivers/usb/dwc3/core.c
> +++ b/drivers/usb/dwc3/core.c
> @@ -1750,6 +1750,60 @@ static struct extcon_dev *dwc3_get_extcon(struct dwc3 *dwc)
>  	return edev;
>  }
>  
> +static int dwc3_read_port_info(struct dwc3 *dwc)
> +{
> +	void __iomem		*regs;
> +	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.
> +	 */
> +	regs = ioremap(dwc->xhci_resources[0].start,
> +				resource_size(&dwc->xhci_resources[0]));
> +	if (IS_ERR(regs)) {
> +		return PTR_ERR(regs);
> +	}
> +
> +	offset = dwc3_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_usb3_ports += XHCI_EXT_PORT_COUNT(temp);
> +		} else if (major_revision <= 0x02) {
> +			dwc->num_usb2_ports += XHCI_EXT_PORT_COUNT(temp);
> +		} else {
> +			dev_err(dwc->dev, "port revision seems wrong\n");
> +			ret = -EINVAL;
> +			goto unmap_reg;
> +		}
> +
> +		offset = dwc3_xhci_find_next_ext_cap(regs, offset,
> +						XHCI_EXT_CAPS_PROTOCOL);
> +	}
> +
> +	temp = readl(regs + DWC3_XHCI_HCSPARAMS1);
> +	if (HCS_MAX_PORTS(temp) != (dwc->num_usb3_ports + dwc->num_usb2_ports)) {
> +		dev_err(dwc->dev, "inconsistency in port info\n");
> +		ret = -EINVAL;
> +		goto unmap_reg;
> +	}
> +
> +	dev_dbg(dwc->dev,
> +		"hs-ports: %d ss-ports: %d\n", dwc->num_usb2_ports, dwc->num_usb3_ports);
> +
> +unmap_reg:
> +	iounmap(regs);
> +	return ret;
> +}
> +
>  static int dwc3_probe(struct platform_device *pdev)
>  {
>  	struct device		*dev = &pdev->dev;
> @@ -1757,6 +1811,7 @@ static int dwc3_probe(struct platform_device *pdev)
>  	struct dwc3		*dwc;
>  
>  	int			ret;
> +	unsigned int		hw_mode;
>  
>  	void __iomem		*regs;
>  
> @@ -1880,6 +1935,20 @@ 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);
> +		if (ret)
> +			goto disable_clks;
> +	} else {
> +		dwc->num_usb2_ports = 1;
> +		dwc->num_usb3_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 4743e918dcaf..229b7da8c5bc 100644
> --- a/drivers/usb/dwc3/core.h
> +++ b/drivers/usb/dwc3/core.h
> @@ -35,6 +35,17 @@
>  
>  #define DWC3_MSG_MAX	500
>  
> +/* Define XHCI Extcap register offsets for getting multiport info */
> +#define XHCI_HCC_PARAMS_OFFSET  0x10
> +#define DWC3_XHCI_HCSPARAMS1   0x04
> +#define XHCI_EXT_CAPS_PROTOCOL  2
> +#define XHCI_HCC_EXT_CAPS(p)    (((p)>>16)&0xffff)
> +#define XHCI_EXT_CAPS_ID(p)     (((p)>>0)&0xff)
> +#define XHCI_EXT_CAPS_NEXT(p)   (((p)>>8)&0xff)

Fix these spacing and naming inconsistency (x vs p).

> +#define XHCI_EXT_PORT_MAJOR(x)  (((x) >> 24) & 0xff)
> +#define XHCI_EXT_PORT_COUNT(x)  (((x) >> 8) & 0xff)
> +#define HCS_MAX_PORTS(p)        (((p) >> 24) & 0x7f)
> +
>  /* Global constants */
>  #define DWC3_PULL_UP_TIMEOUT	500	/* ms */
>  #define DWC3_BOUNCE_SIZE	1024	/* size of a superspeed bulk */
> @@ -1023,6 +1034,10 @@ struct dwc3_scratchpad_array {
>   * @usb_psy: pointer to power supply interface.
>   * @usb2_phy: pointer to USB2 PHY
>   * @usb3_phy: pointer to USB3 PHY
> + * @num_usb2_ports: Indicates the number of usb2 ports to be serviced by the
> + *			controller.

Can we just say "number of usb2 ports".

> + * @num_usb3_ports: Indicates the number of usb3 ports to be serviced by the
> + *			controller.
>   * @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 +1173,8 @@ struct dwc3 {
>  	struct usb_phy		*usb2_phy;
>  	struct usb_phy		*usb3_phy;
>  
> +	u32			num_usb2_ports;
> +	u32			num_usb3_ports;
>  	struct phy		*usb2_generic_phy;
>  	struct phy		*usb3_generic_phy;
>  
> @@ -1645,4 +1662,47 @@ static inline void dwc3_ulpi_exit(struct dwc3 *dwc)
>  { }
>  #endif
>  
> +/**
> + * Find the offset of the extended capabilities with capability ID id.
> + *
> + * @base	PCI MMIO registers base address.
> + * @start	address at which to start looking, (0 or HCC_PARAMS to start at
> + *		beginning of list)
> + * @id		Extended capability ID to search for, or 0 for the next
> + *		capability
> + *
> + * Returns the offset of the next matching extended capability structure.
> + * Some capabilities can occur several times, e.g., the XHCI_EXT_CAPS_PROTOCOL,
> + * and this provides a way to find them all.
> + */

Documentation style is different?

> +
> +static inline int dwc3_xhci_find_next_ext_cap(void __iomem *base, u32 start, int id)
> +{
> +	u32 val;
> +	u32 next;
> +	u32 offset;
> +
> +	offset = start;
> +	if (!start || start == XHCI_HCC_PARAMS_OFFSET) {
> +		val = readl(base + XHCI_HCC_PARAMS_OFFSET);
> +		if (val == ~0)
> +			return 0;
> +		offset = XHCI_HCC_EXT_CAPS(val) << 2;
> +		if (!offset)
> +			return 0;
> +	}
> +	do {
> +		val = readl(base + offset);
> +		if (val == ~0)
> +			return 0;
> +		if (offset != start && (id == 0 || XHCI_EXT_CAPS_ID(val) == id))
> +			return offset;
> +
> +		next = XHCI_EXT_CAPS_NEXT(val);
> +		offset += next << 2;
> +	} while (next);
> +
> +	return 0;
> +}
> +
>  #endif /* __DRIVERS_USB_DWC3_CORE_H */
> -- 
> 2.40.0
> 

My checkpatch reports some errors. Can you check?

Thanks,
Thinh