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

Krishna Kurapati PSSNV
2023-05-16T02:13:02Z

On 5/16/2023 2:38 AM, Bjorn Andersson wrote:
> 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..."?

Hi Bjorn,

I copied this code from xhci-ext-caps.h. The documentation of this
function mentioned PCI in that file. May be Thinh/Mathias can correct us
if this is wrong.

>
>> + * @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.
>

I executed the following command and it didn't give any errors:

./scripts/kernel-doc -none -Werror -function dwc3_xhci_find_next_ext_cap
drivers/usb/dwc3/core.c

I see that even for dwc3_core_init the comments are the same:

/**
* dwc3_core_init - Low-level initialization of DWC3 Core
* @dwc: Pointer to our controller context structure
*
* Returns 0 on success otherwise negative errno.
*/

>> + * 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.
>

Sure, will fix this nit.

Thanks,
Krishna,
>> +
>> + /*
>> + * 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
>>