Re: [PATCH v8 3/9] usb: dwc3: core: Access XHCI address space temporarily to read port info

Bjorn Andersson
2023-05-15T21:06:51Z

On Sun, May 14, 2023 at 11:19:11AM +0530, 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 at least 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@quicinc.com>
> ---
> drivers/usb/dwc3/core.c | 113 ++++++++++++++++++++++++++++++++++++++++
> drivers/usb/dwc3/core.h | 17 +++++-
> 2 files changed, 129 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/usb/dwc3/core.c b/drivers/usb/dwc3/core.c
> index 0beaab932e7d..e983aef1fb93 100644
> --- a/drivers/usb/dwc3/core.c
> +++ b/drivers/usb/dwc3/core.c
> @@ -1767,6 +1767,104 @@ static int dwc3_get_clocks(struct dwc3 *dwc)
> return 0;
> }
>
> +/**
> + * dwc3_xhci_find_next_ext_cap - Find the offset of the extended capabilities
> + * with capability ID id.

() after function name in kernel-doc

> + *
> + * @base: PCI MMIO registers base address.

Should this be "XHCI MMIO..."?

> + * @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.

Return: The offset...

Per https://www.kernel.org/doc/html/next/doc-guide/kernel-doc.html.

> + * Some capabilities can occur several times, e.g., the XHCI_EXT_CAPS_PROTOCOL,
> + * and this provides a way to find them all.
> + */
> +static 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;
> +}
> +
> +static int dwc3_read_port_info(struct dwc3 *dwc)
> +{
> + void __iomem *regs;
> + u32 offset;
> + u32 temp;
> + u8 major_revision;
> + int ret = 0;

Please drop the spacing between type and variable name here, if nothing
else it's inconsistent with the previous function.

Regards,
Bjorn

> +
> + /*
> + * 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,
> + "Unrecognized port major revision %d\n", major_revision);
> + 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,
> + "Mismatched reported MAXPORTS (%d)\n", HCS_MAX_PORTS(temp));
> + 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;
> @@ -1774,6 +1872,7 @@ static int dwc3_probe(struct platform_device *pdev)
> void __iomem *regs;
> struct dwc3 *dwc;
> int ret;
> + unsigned int hw_mode;
>
> dwc = devm_kzalloc(dev, sizeof(*dwc), GFP_KERNEL);
> if (!dwc)
> @@ -1843,6 +1942,20 @@ static int dwc3_probe(struct platform_device *pdev)
> goto err_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 err_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 d56457c02996..d3401963bc27 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(x) (((x) >> 16) & 0xffff)
> +#define XHCI_EXT_CAPS_ID(x) (((x) >> 0) & 0xff)
> +#define XHCI_EXT_CAPS_NEXT(x) (((x) >> 8) & 0xff)
> +#define XHCI_EXT_PORT_MAJOR(x) (((x) >> 24) & 0xff)
> +#define XHCI_EXT_PORT_COUNT(x) (((x) >> 8) & 0xff)
> +#define HCS_MAX_PORTS(x) (((x) >> 24) & 0x7f)
> +
> /* Global constants */
> #define DWC3_PULL_UP_TIMEOUT 500 /* ms */
> #define DWC3_BOUNCE_SIZE 1024 /* size of a superspeed bulk */
> @@ -1025,6 +1036,8 @@ 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: number of usb2 ports.
> + * @num_usb3_ports: number of usb3 ports.
> * @usb2_generic_phy: pointer to USB2 PHY
> * @usb3_generic_phy: pointer to USB3 PHY
> * @phys_ready: flag to indicate that PHYs are ready
> @@ -1162,6 +1175,9 @@ struct dwc3 {
> struct usb_phy *usb2_phy;
> struct usb_phy *usb3_phy;
>
> + u8 num_usb2_ports;
> + u8 num_usb3_ports;
> +
> struct phy *usb2_generic_phy;
> struct phy *usb3_generic_phy;
>
> @@ -1649,5 +1665,4 @@ static inline int dwc3_ulpi_init(struct dwc3 *dwc)
> static inline void dwc3_ulpi_exit(struct dwc3 *dwc)
> { }
> #endif
> -
> #endif /* __DRIVERS_USB_DWC3_CORE_H */
> --
> 2.40.0
>