From: "Peter Chen (CIX)" <peter.chen@kernel.org>
To: pawell@cadence.com
Cc: Roger Quadros <rogerq@kernel.org>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
Bjorn Helgaas <bhelgaas@google.com>,
linux-usb@vger.kernel.org, linux-kernel@vger.kernel.org,
linux-pci@vger.kernel.org
Subject: Re: [PATCH v2] usb: cdnsp: Add support for device-only configuration
Date: Wed, 6 May 2026 10:36:30 +0800 [thread overview]
Message-ID: <afqpLr/BMMuN0pTg@nchen-desktop> (raw)
In-Reply-To: <20260505-device_only_branch_v2-v2-1-98cc19fbd02a@cadence.com>
On 26-05-05 12:02:56, Pawel Laszczak via B4 Relay wrote:
> From: Pawel Laszczak <pawell@cadence.com>
>
> This patch introduces support for operating the Cadence USBSSP (cdnsp)
> controller in a peripheral-only mode, bypassing the Dual-Role Device (DRD)
> logic.
I still debate peripheral-only not equals to no-drd, see below.
>
> The change in BAR indexing (from BAR 2 to BAR 1) is a direct
> consequence of switching from 64-bit to 32-bit addressing in the
> Peripheral-only configuration.
>
> Tested on PCI platform with Device-only configuration. Platform-side
> changes are included to support the PCI glue layer's property injection.
>
> Acked-by: Bjorn Helgaas <bhelgaas@google.com> # pci_ids.h
> Signed-off-by: Pawel Laszczak <pawell@cadence.com>
> ---
> This is a resubmission of the previous patch, now based on the restored
> commit e4d7362dc9cd ("usb: cdns3: Add USBSSP platform driver support").
>
> Since the "usb: cdns3: Add USBSSP platform driver support" patch was
> reverted and then re-added, this version (v2) ensures compatibility
> with the latest tree state.
> ---
> v2:
> - Changed otg_irq to be optionali.
> - Added cdns->no_drd check in cdns_power_is_lost.
> - Added cdns->no_drd check in cdns_get_id.
> ---
> drivers/usb/cdns3/cdns3-plat.c | 23 ++++++++++++-----------
> drivers/usb/cdns3/cdnsp-pci.c | 33 ++++++++++++++++++++++++---------
> drivers/usb/cdns3/core.c | 3 ++-
> drivers/usb/cdns3/core.h | 3 +++
> drivers/usb/cdns3/drd.c | 22 ++++++++++++++++++++--
> include/linux/pci_ids.h | 1 +
> 6 files changed, 62 insertions(+), 23 deletions(-)
>
> diff --git a/drivers/usb/cdns3/cdns3-plat.c b/drivers/usb/cdns3/cdns3-plat.c
> index 3fe3109a3688..1af19360410e 100644
> --- a/drivers/usb/cdns3/cdns3-plat.c
> +++ b/drivers/usb/cdns3/cdns3-plat.c
> @@ -113,21 +113,22 @@ static int cdns3_plat_probe(struct platform_device *pdev)
>
> cdns->dev_regs = regs;
>
> - cdns->otg_irq = platform_get_irq_byname(pdev, "otg");
> - if (cdns->otg_irq < 0)
> - return dev_err_probe(dev, cdns->otg_irq,
> - "Failed to get otg IRQ\n");
> -
> - res = platform_get_resource_byname(pdev, IORESOURCE_MEM, "otg");
> - if (!res) {
> - dev_err(dev, "couldn't get otg resource\n");
> - return -ENXIO;
> + cdns->otg_irq = platform_get_irq_byname_optional(pdev, "otg");
> +
> + if (cdns->otg_irq < 0) {
> + dev_dbg(dev, "Device-only mode: DRD support disabled\n");
Why "Device-only", just no DRD support?
> + cdns->no_drd = 1;
> + } else {
> + res = platform_get_resource_byname(pdev, IORESOURCE_MEM, "otg");
> + if (!res) {
> + dev_err(dev, "couldn't get otg resource\n");
> + return -ENXIO;
> + }
> + cdns->otg_res = *res;
> }
>
> cdns->phyrst_a_enable = device_property_read_bool(dev, "cdns,phyrst-a-enable");
>
> - cdns->otg_res = *res;
> -
> cdns->wakeup_irq = platform_get_irq_byname_optional(pdev, "wakeup");
> if (cdns->wakeup_irq == -EPROBE_DEFER)
> return cdns->wakeup_irq;
> diff --git a/drivers/usb/cdns3/cdnsp-pci.c b/drivers/usb/cdns3/cdnsp-pci.c
> index 432007cfe695..28e16b094525 100644
> --- a/drivers/usb/cdns3/cdnsp-pci.c
> +++ b/drivers/usb/cdns3/cdnsp-pci.c
> @@ -29,10 +29,15 @@ struct cdnsp_wrap {
> #define RES_HOST_ID 3
> #define RES_DEV_ID 4
> #define RES_DRD_ID 5
> -
> +/* DRD PCI configuration - 64-bit addressing */
> +/* First PCI function */
> #define PCI_BAR_HOST 0
> -#define PCI_BAR_OTG 0
> #define PCI_BAR_DEV 2
> +/* Second PCI function */
> +#define PCI_BAR_OTG 0
> +/* Device only PCI configuration - 32-bit addressing */
> +/* First PCI function */
> +#define PCI_BAR_ONLY_DEV 1
>
> #define PCI_DEV_FN_HOST_DEVICE 0
> #define PCI_DEV_FN_OTG 1
> @@ -65,6 +70,7 @@ static int cdnsp_pci_probe(struct pci_dev *pdev,
> struct cdnsp_wrap *wrap;
> struct resource *res;
> struct pci_dev *func;
> + bool no_drd = false;
> int ret = 0;
>
> /*
> @@ -75,11 +81,14 @@ static int cdnsp_pci_probe(struct pci_dev *pdev,
> pdev->devfn != PCI_DEV_FN_OTG))
> return -EINVAL;
>
> + if (pdev->device == PCI_DEVICE_ID_CDNS_UDC_USBSSP)
> + no_drd = true;
> +
> func = cdnsp_get_second_fun(pdev);
> - if (!func)
> + if (!func && !no_drd)
> return -EINVAL;
>
> - if (func->class == PCI_CLASS_SERIAL_USB_XHCI ||
> + if ((func && func->class == PCI_CLASS_SERIAL_USB_XHCI) ||
> pdev->class == PCI_CLASS_SERIAL_USB_XHCI) {
> ret = -EINVAL;
> goto put_pci;
> @@ -93,7 +102,7 @@ static int cdnsp_pci_probe(struct pci_dev *pdev,
>
> pci_set_master(pdev);
>
> - if (pci_is_enabled(func)) {
> + if (func && pci_is_enabled(func)) {
> wrap = pci_get_drvdata(func);
> } else {
> wrap = kzalloc_obj(*wrap);
> @@ -106,10 +115,12 @@ static int cdnsp_pci_probe(struct pci_dev *pdev,
> res = wrap->dev_res;
>
> if (pdev->devfn == PCI_DEV_FN_HOST_DEVICE) {
> + int bar_dev = no_drd ? PCI_BAR_ONLY_DEV : PCI_BAR_DEV;
> +
> /* Function 0: host(BAR_0) + device(BAR_2). */
> dev_dbg(&pdev->dev, "Initialize Device resources\n");
> - res[RES_DEV_ID].start = pci_resource_start(pdev, PCI_BAR_DEV);
> - res[RES_DEV_ID].end = pci_resource_end(pdev, PCI_BAR_DEV);
> + res[RES_DEV_ID].start = pci_resource_start(pdev, bar_dev);
> + res[RES_DEV_ID].end = pci_resource_end(pdev, bar_dev);
> res[RES_DEV_ID].name = "dev";
> res[RES_DEV_ID].flags = IORESOURCE_MEM;
> dev_dbg(&pdev->dev, "USBSSP-DEV physical base addr: %pa\n",
> @@ -145,7 +156,7 @@ static int cdnsp_pci_probe(struct pci_dev *pdev,
> wrap->dev_res[RES_IRQ_OTG_ID].flags = IORESOURCE_IRQ;
> }
>
> - if (pci_is_enabled(func)) {
> + if (no_drd || pci_is_enabled(func)) {
> /* set up platform device info */
> pdata.override_apb_timeout = CHICKEN_APB_TIMEOUT_VALUE;
> memset(&plat_info, 0, sizeof(plat_info));
> @@ -185,13 +196,17 @@ static void cdnsp_pci_remove(struct pci_dev *pdev)
> if (wrap->devfn == pdev->devfn)
> platform_device_unregister(wrap->plat_dev);
>
> - if (!pci_is_enabled(func))
> + if (!func || !pci_is_enabled(func))
> kfree(wrap);
>
> pci_dev_put(func);
> }
>
> static const struct pci_device_id cdnsp_pci_ids[] = {
> + { PCI_DEVICE(PCI_VENDOR_ID_CDNS, PCI_DEVICE_ID_CDNS_UDC_USBSSP),
> + .class = PCI_CLASS_SERIAL_USB_DEVICE },
> + { PCI_DEVICE(PCI_VENDOR_ID_CDNS, PCI_DEVICE_ID_CDNS_UDC_USBSSP),
> + .class = PCI_CLASS_SERIAL_USB_CDNS },
> { PCI_DEVICE(PCI_VENDOR_ID_CDNS, PCI_DEVICE_ID_CDNS_USBSSP),
> .class = PCI_CLASS_SERIAL_USB_DEVICE },
> { PCI_DEVICE(PCI_VENDOR_ID_CDNS, PCI_DEVICE_ID_CDNS_USBSSP),
> diff --git a/drivers/usb/cdns3/core.c b/drivers/usb/cdns3/core.c
> index 6a8d1fefbc0d..504bdf13ea80 100644
> --- a/drivers/usb/cdns3/core.c
> +++ b/drivers/usb/cdns3/core.c
> @@ -70,7 +70,8 @@ static void cdns_role_stop(struct cdns *cdns)
> static void cdns_exit_roles(struct cdns *cdns)
> {
> cdns_role_stop(cdns);
> - cdns_drd_exit(cdns);
> + if (!cdns->no_drd)
> + cdns_drd_exit(cdns);
> }
>
> /**
> diff --git a/drivers/usb/cdns3/core.h b/drivers/usb/cdns3/core.h
> index bca973b999a4..ef3f50169246 100644
> --- a/drivers/usb/cdns3/core.h
> +++ b/drivers/usb/cdns3/core.h
> @@ -84,6 +84,8 @@ struct cdns3_platform_data {
> * value in CHICKEN_BITS_3 will be preserved.
> * @gadget_init: pointer to gadget initialization function
> * @host_init: pointer to host initialization function
> + * @no_drd: DRD register block is inaccessible - driver handles only
> + * device mode.
> */
> struct cdns {
> struct device *dev;
> @@ -124,6 +126,7 @@ struct cdns {
> u32 override_apb_timeout;
> int (*gadget_init)(struct cdns *cdns);
> int (*host_init)(struct cdns *cdns);
> + bool no_drd;
> };
>
> int cdns_hw_role_switch(struct cdns *cdns);
> diff --git a/drivers/usb/cdns3/drd.c b/drivers/usb/cdns3/drd.c
> index 84fb38a5723a..8e8414c2e994 100644
> --- a/drivers/usb/cdns3/drd.c
> +++ b/drivers/usb/cdns3/drd.c
> @@ -87,6 +87,9 @@ int cdns_get_id(struct cdns *cdns)
> {
> int id;
>
> + if (cdns->no_drd)
> + return 0;
> +
> id = readl(&cdns->otg_regs->sts) & OTGSTS_ID_VALUE;
> dev_dbg(cdns->dev, "OTG ID: %d", id);
>
> @@ -107,7 +110,7 @@ void cdns_clear_vbus(struct cdns *cdns)
> {
> u32 reg;
>
> - if (cdns->version != CDNSP_CONTROLLER_V2)
> + if (cdns->version != CDNSP_CONTROLLER_V2 || cdns->no_drd)
> return;
>
> reg = readl(&cdns->otg_cdnsp_regs->override);
> @@ -120,7 +123,7 @@ void cdns_set_vbus(struct cdns *cdns)
> {
> u32 reg;
>
> - if (cdns->version != CDNSP_CONTROLLER_V2)
> + if (cdns->version != CDNSP_CONTROLLER_V2 || cdns->no_drd)
> return;
>
> reg = readl(&cdns->otg_cdnsp_regs->override);
> @@ -234,6 +237,9 @@ int cdns_drd_gadget_on(struct cdns *cdns)
> u32 ready_bit;
> int ret, val;
>
> + if (cdns->no_drd)
> + return 0;
> +
> /* switch OTG core */
> writel(OTGCMD_DEV_BUS_REQ | reg, &cdns->otg_regs->cmd);
>
> @@ -265,6 +271,9 @@ void cdns_drd_gadget_off(struct cdns *cdns)
> {
> u32 val;
>
> + if (cdns->no_drd)
> + return;
> +
> /*
> * Driver should wait at least 10us after disabling Device
> * before turning-off Device (DEV_BUS_DROP).
> @@ -392,6 +401,12 @@ int cdns_drd_init(struct cdns *cdns)
> u32 state, reg;
> int ret;
>
> + if (cdns->no_drd) {
> + cdns->version = CDNSP_CONTROLLER_V2;
> + cdns->dr_mode = USB_DR_MODE_PERIPHERAL;
> + return 0;
> + }
> +
I still concern this, CIX SoC has host-only configuration, and it
needs to use cdns3 driver for low power purpose, eg set D3 mode
for controller.
> regs = devm_ioremap_resource(cdns->dev, &cdns->otg_res);
> if (IS_ERR(regs))
> return PTR_ERR(regs);
> @@ -500,6 +515,9 @@ int cdns_drd_exit(struct cdns *cdns)
> /* Indicate the cdns3 core was power lost before */
> bool cdns_power_is_lost(struct cdns *cdns)
> {
> + if (cdns->no_drd)
> + return false;
> +
You may not just return false, would you please find one host and one device
register to compare, we need this feature.
Peter
> if (cdns->version == CDNS3_CONTROLLER_V0) {
> if (!(readl(&cdns->otg_v0_regs->simulate) & BIT(0)))
> return true;
> diff --git a/include/linux/pci_ids.h b/include/linux/pci_ids.h
> index 24cb42f66e4b..a6b9b6f6d8cc 100644
> --- a/include/linux/pci_ids.h
> +++ b/include/linux/pci_ids.h
> @@ -2424,6 +2424,7 @@
> #define PCI_DEVICE_ID_CDNS_USBSS 0x0100
> #define PCI_DEVICE_ID_CDNS_USB 0x0120
> #define PCI_DEVICE_ID_CDNS_USBSSP 0x0200
> +#define PCI_DEVICE_ID_CDNS_UDC_USBSSP 0x0400
>
> #define PCI_VENDOR_ID_ARECA 0x17d3
> #define PCI_DEVICE_ID_ARECA_1110 0x1110
>
> ---
> base-commit: 9d0d467c3572e93c5faa2e5906a8bbcd70b24efd
> change-id: 20260505-device_only_branch_v2-53692f329752
>
> Best regards,
> --
> Pawel Laszczak <pawell@cadence.com>
>
>
--
Best regards,
Peter
next prev parent reply other threads:[~2026-05-06 2:36 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-05-05 10:02 [PATCH v2] usb: cdnsp: Add support for device-only configuration Pawel Laszczak via B4 Relay
2026-05-06 2:36 ` Peter Chen (CIX) [this message]
2026-05-06 10:31 ` Pawel Laszczak
2026-05-07 1:05 ` Peter Chen (CIX)
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