* [PATCH v2] usb: cdnsp: Add support for device-only configuration
@ 2026-05-05 10:02 Pawel Laszczak via B4 Relay
2026-05-06 2:36 ` Peter Chen (CIX)
0 siblings, 1 reply; 3+ messages in thread
From: Pawel Laszczak via B4 Relay @ 2026-05-05 10:02 UTC (permalink / raw)
To: Peter Chen, Roger Quadros, Greg Kroah-Hartman, Bjorn Helgaas
Cc: linux-usb, linux-kernel, linux-pci, Pawel Laszczak
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.
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");
+ 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;
+ }
+
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;
+
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>
^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [PATCH v2] usb: cdnsp: Add support for device-only configuration
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)
2026-05-06 10:31 ` Pawel Laszczak
0 siblings, 1 reply; 3+ messages in thread
From: Peter Chen (CIX) @ 2026-05-06 2:36 UTC (permalink / raw)
To: pawell
Cc: Roger Quadros, Greg Kroah-Hartman, Bjorn Helgaas, linux-usb,
linux-kernel, linux-pci
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
^ permalink raw reply [flat|nested] 3+ messages in thread
* RE: [PATCH v2] usb: cdnsp: Add support for device-only configuration
2026-05-06 2:36 ` Peter Chen (CIX)
@ 2026-05-06 10:31 ` Pawel Laszczak
0 siblings, 0 replies; 3+ messages in thread
From: Pawel Laszczak @ 2026-05-06 10:31 UTC (permalink / raw)
To: Peter Chen (CIX)
Cc: Roger Quadros, Greg Kroah-Hartman, Bjorn Helgaas,
linux-usb@vger.kernel.org, linux-kernel@vger.kernel.org,
linux-pci@vger.kernel.org
>
>
>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.
I think I understand your concerns regarding the distinction
between peripheral/host-only mode and the lack of DRD hardware.
My proposal for the revised patch description is as follows:
This patch introduces support for the Cadence USBSSP (cdnsp)
controller in hardware configurations where the Dual-Role Device (DRD)
register block is not implemented or is inaccessible.
In such cases, the driver cannot rely on the DRD logic to manage roles
and must operate exclusively in a fixed peripheral/host mode.
The change in BAR indexing (from BAR 2 to BAR 1) is a direct
consequence of the 32-bit addressing used in this specific
DRD-disabled hardware layout, compared to the 64-bit addressing
used in DRD-enabled configurations.
Tested on a PCI platform with a hardware configuration that lacks
DRD support. Platform-side changes are included to support the PCI
glue layer's property injection to handle this specific layout.
>
>>
>> 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?
I will change it.
>
>> + 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.
If dr_mode is set to 'host' or 'peripheral' and the OTG IRQ is not configured
in the DTS, the driver will detect this as no_drd. This may be inconsistent
with the actual hardware state, as the DRD component might still exist.
It might be safer to revert to the version where no_drd is not detected
based on the otg_irq, and instead add a no_drd property in cdnsp_pci.c.
If necessary, this can also be added to the DTS.
This should fully ensure the correct operation of existing platforms.
With this approach, for the sake of completeness, we could set
USB_DR_MODE_HOST or USB_DR_MODE_PERIPHERAL in the condition
above based on dr_mode.
>
>> 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.
Also this condition will be correct for existing platforms.
Does this look correct to you?
Pawel
>
>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
^ permalink raw reply [flat|nested] 3+ messages in thread
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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)
2026-05-06 10:31 ` Pawel Laszczak
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