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Date:   Mon, 15 May 2023 14:08:26 -0700
From:   Bjorn Andersson <andersson@kernel.org>
To:     Krishna Kurapati <quic_kriskura@quicinc.com>
Cc:     Thinh Nguyen <Thinh.Nguyen@synopsys.com>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Philipp Zabel <p.zabel@pengutronix.de>,
        Andy Gross <agross@kernel.org>,
        Konrad Dybcio <konrad.dybcio@linaro.org>,
        Rob Herring <robh+dt@kernel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>,
        Felipe Balbi <balbi@kernel.org>, linux-usb@vger.kernel.org,
        linux-kernel@vger.kernel.org, linux-arm-msm@vger.kernel.org,
        devicetree@vger.kernel.org, quic_pkondeti@quicinc.com,
        quic_ppratap@quicinc.com, quic_wcheng@quicinc.com,
        quic_jackp@quicinc.com, quic_harshq@quicinc.com,
        ahalaney@redhat.com
Subject: Re: [PATCH v8 3/9] usb: dwc3: core: Access XHCI address space
 temporarily to read port info
Message-ID: <20230515210826.gwvmyrxrtt6yjc44@ripper>
References: <20230514054917.21318-1-quic_kriskura@quicinc.com>
 <20230514054917.21318-4-quic_kriskura@quicinc.com>
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In-Reply-To: <20230514054917.21318-4-quic_kriskura@quicinc.com>
Precedence: bulk

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
>