Re: [PATCH v9 03/10] usb: dwc3: core: Access XHCI address space temporarily to read port info

[Johan Hovold]

On Wed, Jun 21, 2023 at 10:06:21AM +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@xxxxxxxxxxx>
> ---
>  drivers/usb/dwc3/core.c | 62 +++++++++++++++++++++++++++++++++++++++++
>  drivers/usb/dwc3/core.h |  9 ++++++
>  2 files changed, 71 insertions(+)
> 
> diff --git a/drivers/usb/dwc3/core.c b/drivers/usb/dwc3/core.c
> index f6689b731718..32ec05fc242b 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 */
>  
> @@ -1767,6 +1768,52 @@ 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 = 0;
> +	int ret = 0;

ret is never modified, so drop and return 0 unconditionally below.

You can add it back later in the series when you start using it.

> +	u32 val;
> +
> +	/*
> +	 * Remap xHCI address space to access XHCI ext cap regs,
> +	 * since it is needed to get port info.
> +	 */
> +	base = ioremap(dwc->xhci_resources[0].start,
> +				resource_size(&dwc->xhci_resources[0]));
> +	if (IS_ERR(base))
> +		return PTR_ERR(base);
> +
> +	do {
> +		offset = xhci_find_next_ext_cap(base, offset,
> +				XHCI_EXT_CAPS_PROTOCOL);
> +

You can drop this newline.

> +		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_err(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);

Nit: I'd add a newline here.

> +	return ret;
> +}
> +
>  static int dwc3_probe(struct platform_device *pdev)
>  {
>  	struct device		*dev = &pdev->dev;
> @@ -1774,6 +1821,7 @@ 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)
> @@ -1854,6 +1902,20 @@ static int dwc3_probe(struct platform_device *pdev)
>  			goto err_disable_clks;
>  	}
>  
> +	/*
> +	 * Currently only 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 8b1295e4dcdd..42fb17aa66fa 100644
> --- a/drivers/usb/dwc3/core.h
> +++ b/drivers/usb/dwc3/core.h
> @@ -33,6 +33,10 @@
>  
>  #include <linux/power_supply.h>
>  
> +#define XHCI_EXT_PORT_MAJOR(x)	(((x) >> 24) & 0xff)
> +#define XHCI_EXT_PORT_MINOR(x)	(((x) >> 16) & 0xff)
> +#define XHCI_EXT_PORT_COUNT(x)	(((x) >> 8) & 0xff)

Again, don't copy defines from xhci.

Looks like these should be moved to the xhci-ext-caps.h header along
with struct xhci_protocol_caps.

> +
>  #define DWC3_MSG_MAX	500
>  
>  /* Global constants */
> @@ -1029,6 +1033,8 @@ 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.

Again, please drop the full stops ('.').

Johan