RE: [PATCH v2] usb: cdnsp: Add support for device-only configuration

[Pawel Laszczak]

>
>
>On 26-05-05 12:02:56, Pawel Laszczak via B4 Relay wrote:
>> From: Pawel Laszczak <pawell@xxxxxxxxxxx>
>>
>> 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@xxxxxxxxxx> # pci_ids.h
>> Signed-off-by: Pawel Laszczak <pawell@xxxxxxxxxxx>
>> ---
>> 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@xxxxxxxxxxx>
>>
>>
>
>--
>
>Best regards,
>Peter