Re: [PATCH v18 2/9] usb: dwc3: core: Access XHCI address space temporarily to read port info

[Thinh Nguyen]

On Tue, Mar 26, 2024, Krishna Kurapati wrote:
> All DWC3 Multi Port controllers that exist today only support host mode.
> 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@xxxxxxxxxxx>
> Reviewed-by: Johan Hovold <johan+linaro@xxxxxxxxxx>
> ---
>  drivers/usb/dwc3/core.c | 61 +++++++++++++++++++++++++++++++++++++++++
>  drivers/usb/dwc3/core.h |  5 ++++
>  2 files changed, 66 insertions(+)
> 
> diff --git a/drivers/usb/dwc3/core.c b/drivers/usb/dwc3/core.c
> index 3e55838c0001..fab7664c12c0 100644
> --- a/drivers/usb/dwc3/core.c
> +++ b/drivers/usb/dwc3/core.c
> @@ -39,6 +39,7 @@
>  #include "io.h"
>  
>  #include "debug.h"
> +#include "../host/xhci-ext-caps.h"
>  
>  #define DWC3_DEFAULT_AUTOSUSPEND_DELAY	5000 /* ms */
>  
> @@ -1879,10 +1880,56 @@ static int dwc3_get_clocks(struct dwc3 *dwc)
>  	return 0;
>  }
>  
> +static int dwc3_read_port_info(struct dwc3 *dwc)
> +{
> +	void __iomem *base;
> +	u8 major_revision;
> +	u32 offset;
> +	u32 val;
> +
> +	/*
> +	 * Remap xHCI address space to access XHCI ext cap regs since it is
> +	 * needed to get information on number of ports present.
> +	 */
> +	base = ioremap(dwc->xhci_resources[0].start,
> +		       resource_size(&dwc->xhci_resources[0]));
> +	if (IS_ERR(base))
> +		return PTR_ERR(base);

Looks like you forgot to address some of the comments you said you'd
update previously if you submit a new version to the series.

[*] https://lore.kernel.org/linux-usb/af73110d-e13e-4183-af11-aed869ac0a31@xxxxxxxxxxx/

BR,
Thinh

> +
> +	offset = 0;
> +	do {
> +		offset = xhci_find_next_ext_cap(base, offset,
> +						XHCI_EXT_CAPS_PROTOCOL);
> +		if (!offset)
> +			break;
> +
> +		val = readl(base + offset);
> +		major_revision = XHCI_EXT_PORT_MAJOR(val);
> +
> +		val = readl(base + offset + 0x08);
> +		if (major_revision == 0x03) {
> +			dwc->num_usb3_ports += XHCI_EXT_PORT_COUNT(val);
> +		} else if (major_revision <= 0x02) {
> +			dwc->num_usb2_ports += XHCI_EXT_PORT_COUNT(val);
> +		} else {
> +			dev_warn(dwc->dev, "unrecognized port major revision %d\n",
> +				 major_revision);
> +		}
> +	} while (1);
> +
> +	dev_dbg(dwc->dev, "hs-ports: %u ss-ports: %u\n",
> +		dwc->num_usb2_ports, dwc->num_usb3_ports);
> +
> +	iounmap(base);
> +
> +	return 0;
> +}
> +
>  static int dwc3_probe(struct platform_device *pdev)
>  {
>  	struct device		*dev = &pdev->dev;
>  	struct resource		*res, dwc_res;
> +	unsigned int		hw_mode;
>  	void __iomem		*regs;
>  	struct dwc3		*dwc;
>  	int			ret;
> @@ -1966,6 +2013,20 @@ static int dwc3_probe(struct platform_device *pdev)
>  			goto err_disable_clks;
>  	}
>  
> +	/*
> +	 * Currently only DWC3 controllers that are host-only capable
> +	 * can have more than one port.
> +	 */
> +	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 c07edfc954f7..40b00a895a2a 100644
> --- a/drivers/usb/dwc3/core.h
> +++ b/drivers/usb/dwc3/core.h
> @@ -1039,6 +1039,8 @@ struct dwc3_scratchpad_array {
>   * @usb3_phy: pointer to USB3 PHY
>   * @usb2_generic_phy: pointer to USB2 PHY
>   * @usb3_generic_phy: pointer to USB3 PHY
> + * @num_usb2_ports: number of USB2 ports
> + * @num_usb3_ports: number of USB3 ports
>   * @phys_ready: flag to indicate that PHYs are ready
>   * @ulpi: pointer to ulpi interface
>   * @ulpi_ready: flag to indicate that ULPI is initialized
> @@ -1186,6 +1188,9 @@ struct dwc3 {
>  	struct phy		*usb2_generic_phy;
>  	struct phy		*usb3_generic_phy;
>  
> +	u8			num_usb2_ports;
> +	u8			num_usb3_ports;
> +
>  	bool			phys_ready;
>  
>  	struct ulpi		*ulpi;
> -- 
> 2.34.1
>