[PATCH v9 2/2] usb: cdnsp: Add support for device-only configuration
From: Pawel Laszczak via B4 Relay
Date: Thu May 21 2026 - 04:01:27 EST
From: Pawel Laszczak <pawell@xxxxxxxxxxx>
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.
Acked-by: Peter Chen <peter.chen@xxxxxxxxxx>
Acked-by: Bjorn Helgaas <bhelgaas@xxxxxxxxxx>
Signed-off-by: Pawel Laszczak <pawell@xxxxxxxxxxx>
Reported-by: kernel test robot <lkp@xxxxxxxxx>
Closes: https://lore.kernel.org/oe-kbuild-all/202605141023.18vWXyw3-lkp@xxxxxxxxx/
---
v9:
- Switch to the clean generic fallback "cdns,cdnsp" in driver and PCI glue.
v8:
- Use 'cdns,cdnsp-no-drd' compatible string to trigger no-DRD logic.
- Update PCI glue layer to inject the new compatible string.
v7:
- Use 'cdns,no-drd' instead of 'no_drd' to match updated bindings.
- Fix "uninitialized variable" warning in cdns_drd_host_on() by
initializing 'ret' to 0.
---
drivers/usb/cdns3/cdns3-plat.c | 30 ++++++++++++++++----------
drivers/usb/cdns3/cdnsp-pci.c | 48 ++++++++++++++++++++++++++++++++++--------
drivers/usb/cdns3/core.c | 3 ++-
drivers/usb/cdns3/core.h | 4 ++++
drivers/usb/cdns3/drd.c | 45 ++++++++++++++++++++++++++++++++++++---
5 files changed, 106 insertions(+), 24 deletions(-)
diff --git a/drivers/usb/cdns3/cdns3-plat.c b/drivers/usb/cdns3/cdns3-plat.c
index 3fe3109a3688..0d29c3cf58f1 100644
--- a/drivers/usb/cdns3/cdns3-plat.c
+++ b/drivers/usb/cdns3/cdns3-plat.c
@@ -81,6 +81,12 @@ static int cdns3_plat_probe(struct platform_device *pdev)
if (cdns->pdata && cdns->pdata->override_apb_timeout)
cdns->override_apb_timeout = cdns->pdata->override_apb_timeout;
+ if (device_is_compatible(dev, "cdns,cdnsp")) {
+ cdns->no_drd = true;
+ cdns->version = CDNSP_CONTROLLER_V2;
+ dev_dbg(dev, "No DRD support\n");
+ }
+
platform_set_drvdata(pdev, cdns);
ret = platform_get_irq_byname(pdev, "host");
@@ -113,21 +119,22 @@ 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;
+ if (!cdns->no_drd) {
+ 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_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;
@@ -338,6 +345,7 @@ static const struct dev_pm_ops cdns3_pm_ops = {
#ifdef CONFIG_OF
static const struct of_device_id of_cdns3_match[] = {
{ .compatible = "cdns,usb3" },
+ { .compatible = "cdns,cdnsp" },
{ },
};
MODULE_DEVICE_TABLE(of, of_cdns3_match);
diff --git a/drivers/usb/cdns3/cdnsp-pci.c b/drivers/usb/cdns3/cdnsp-pci.c
index 432007cfe695..c38a3dc7111a 100644
--- a/drivers/usb/cdns3/cdnsp-pci.c
+++ b/drivers/usb/cdns3/cdnsp-pci.c
@@ -19,6 +19,7 @@
struct cdnsp_wrap {
struct platform_device *plat_dev;
+ struct property_entry prop[3];
struct resource dev_res[6];
int devfn;
};
@@ -29,10 +30,15 @@ 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
@@ -40,6 +46,7 @@ struct cdnsp_wrap {
#define PCI_DRIVER_NAME "cdns-pci-usbssp"
#define PLAT_DRIVER_NAME "cdns-usb3"
+#define PCI_DEVICE_ID_CDNS_UDC_USBSSP 0x0400
#define CHICKEN_APB_TIMEOUT_VALUE 0x1C20
static struct pci_dev *cdnsp_get_second_fun(struct pci_dev *pdev)
@@ -65,6 +72,7 @@ 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 +83,14 @@ 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 +104,7 @@ 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 +117,12 @@ 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",
@@ -145,9 +158,21 @@ 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)) {
+ u8 idx = 0;
+
/* set up platform device info */
pdata.override_apb_timeout = CHICKEN_APB_TIMEOUT_VALUE;
+
+ if (no_drd) {
+ wrap->prop[idx++] = PROPERTY_ENTRY_STRING("compatible",
+ "cdns,cdnsp");
+ wrap->prop[idx++] = PROPERTY_ENTRY_STRING("dr_mode", "peripheral");
+ } else {
+ wrap->prop[idx++] = PROPERTY_ENTRY_STRING("dr_mode", "otg");
+ wrap->prop[idx++] = PROPERTY_ENTRY_BOOL("usb-role-switch");
+ }
+
memset(&plat_info, 0, sizeof(plat_info));
plat_info.parent = &pdev->dev;
plat_info.fwnode = pdev->dev.fwnode;
@@ -158,6 +183,7 @@ static int cdnsp_pci_probe(struct pci_dev *pdev,
plat_info.dma_mask = pdev->dma_mask;
plat_info.data = &pdata;
plat_info.size_data = sizeof(pdata);
+ plat_info.properties = wrap->prop;
wrap->devfn = pdev->devfn;
/* register platform device */
wrap->plat_dev = platform_device_register_full(&plat_info);
@@ -185,13 +211,17 @@ 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..8c492fda924c 100644
--- a/drivers/usb/cdns3/core.h
+++ b/drivers/usb/cdns3/core.h
@@ -84,6 +84,9 @@ 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. The controller is hardwired to
+ * single role (host or device) or the logic for role switching is
+ * missing.
*/
struct cdns {
struct device *dev;
@@ -124,6 +127,7 @@ 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..d2bb682e4552 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);
@@ -179,7 +182,10 @@ static void cdns_otg_enable_irq(struct cdns *cdns)
int cdns_drd_host_on(struct cdns *cdns)
{
u32 val, ready_bit;
- int ret;
+ int ret = 0;
+
+ if (cdns->no_drd)
+ goto phy_set;
/* Enable host mode. */
writel(OTGCMD_HOST_BUS_REQ | OTGCMD_OTG_DIS,
@@ -197,6 +203,7 @@ int cdns_drd_host_on(struct cdns *cdns)
if (ret)
dev_err(cdns->dev, "timeout waiting for xhci_ready\n");
+phy_set:
phy_set_mode(cdns->usb2_phy, PHY_MODE_USB_HOST);
phy_set_mode(cdns->usb3_phy, PHY_MODE_USB_HOST);
return ret;
@@ -210,6 +217,9 @@ void cdns_drd_host_off(struct cdns *cdns)
{
u32 val;
+ if (cdns->no_drd)
+ goto phy_set;
+
writel(OTGCMD_HOST_BUS_DROP | OTGCMD_DEV_BUS_DROP |
OTGCMD_DEV_POWER_OFF | OTGCMD_HOST_POWER_OFF,
&cdns->otg_regs->cmd);
@@ -218,6 +228,8 @@ void cdns_drd_host_off(struct cdns *cdns)
readl_poll_timeout_atomic(&cdns->otg_regs->state, val,
!(val & OTGSTATE_HOST_STATE_MASK),
1, 2000000);
+
+phy_set:
phy_set_mode(cdns->usb2_phy, PHY_MODE_INVALID);
phy_set_mode(cdns->usb3_phy, PHY_MODE_INVALID);
}
@@ -234,6 +246,9 @@ int cdns_drd_gadget_on(struct cdns *cdns)
u32 ready_bit;
int ret, val;
+ if (cdns->no_drd)
+ goto phy_set;
+
/* switch OTG core */
writel(OTGCMD_DEV_BUS_REQ | reg, &cdns->otg_regs->cmd);
@@ -251,6 +266,7 @@ int cdns_drd_gadget_on(struct cdns *cdns)
return ret;
}
+phy_set:
phy_set_mode(cdns->usb2_phy, PHY_MODE_USB_DEVICE);
phy_set_mode(cdns->usb3_phy, PHY_MODE_USB_DEVICE);
return 0;
@@ -265,6 +281,9 @@ void cdns_drd_gadget_off(struct cdns *cdns)
{
u32 val;
+ if (cdns->no_drd)
+ goto phy_set;
+
/*
* Driver should wait at least 10us after disabling Device
* before turning-off Device (DEV_BUS_DROP).
@@ -277,6 +296,8 @@ void cdns_drd_gadget_off(struct cdns *cdns)
readl_poll_timeout_atomic(&cdns->otg_regs->state, val,
!(val & OTGSTATE_DEV_STATE_MASK),
1, 2000000);
+
+phy_set:
phy_set_mode(cdns->usb2_phy, PHY_MODE_INVALID);
phy_set_mode(cdns->usb3_phy, PHY_MODE_INVALID);
}
@@ -392,6 +413,18 @@ int cdns_drd_init(struct cdns *cdns)
u32 state, reg;
int ret;
+ if (cdns->no_drd) {
+ cdns->dr_mode = usb_get_dr_mode(cdns->dev);
+
+ if (cdns->dr_mode != USB_DR_MODE_HOST &&
+ cdns->dr_mode != USB_DR_MODE_PERIPHERAL) {
+ dev_err(cdns->dev, "Incorrect dr_mode\n");
+ return -EINVAL;
+ }
+
+ return 0;
+ }
+
regs = devm_ioremap_resource(cdns->dev, &cdns->otg_res);
if (IS_ERR(regs))
return PTR_ERR(regs);
@@ -492,6 +525,9 @@ int cdns_drd_init(struct cdns *cdns)
int cdns_drd_exit(struct cdns *cdns)
{
+ if (cdns->no_drd)
+ return 0;
+
cdns_otg_disable_irq(cdns);
return 0;
@@ -500,6 +536,9 @@ 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;
--
2.43.0