Re: [PATCH v8 5/6] misc: pci_endpoint_test: Add doorbell test case

[Frank Li <Frank.li@nxp.com>]

On Sun, Nov 24, 2024 at 07:21:28PM +0530, Manivannan Sadhasivam wrote:
> On Sat, Nov 16, 2024 at 09:40:45AM -0500, Frank Li wrote:
> > Add three registers: PCIE_ENDPOINT_TEST_DB_BAR, PCIE_ENDPOINT_TEST_DB_ADDR,
> > and PCIE_ENDPOINT_TEST_DB_DATA.
> >
> > Trigger the doorbell by writing data from PCI_ENDPOINT_TEST_DB_DATA to the
> > address provided by PCI_ENDPOINT_TEST_DB_OFFSET and wait for endpoint
> > feedback.
> >
> > Add two command to COMMAND_ENABLE_DOORBELL and COMMAND_DISABLE_DOORBELL
> > to enable EP side's doorbell support and avoid compatible problem.
>
> Can you explain the 'compatible problem' and how this patch avoids it? Just for
> the sake of completeness.
>
> >
> > 		Host side new driver	Host side old driver
> > EP: new driver		S			F
> > EP: old driver		F			F
> >
> > S: If EP side support MSI, 'pcitest -B' return success.
> >    If EP side doesn't support MSI, the same to 'F'.
> >
> > F: 'pcitest -B' return failure, other case as usual.
> >
> > Tested-by: Niklas Cassel <cassel@kernel.org>
> > Signed-off-by: Frank Li <Frank.Li@nxp.com>
> > ---
> > Change form v6 to v8
> > - none
> >
> > Change from v5 to v6
> > - %s/PCI_ENDPOINT_TEST_DB_ADDR/PCI_ENDPOINT_TEST_DB_OFFSET/g
> >
> > Change from v4 to v5
> > - remove unused varible
> > - add irq_type at pci_endpoint_test_doorbell();
> >
> > change from v3 to v4
> > - Add COMMAND_ENABLE_DOORBELL and COMMAND_DISABLE_DOORBELL.
> > - Remove new DID requirement.
> > ---
> >  drivers/misc/pci_endpoint_test.c | 71 ++++++++++++++++++++++++++++++++++++++++
> >  include/uapi/linux/pcitest.h     |  1 +
> >  2 files changed, 72 insertions(+)
> >
> > diff --git a/drivers/misc/pci_endpoint_test.c b/drivers/misc/pci_endpoint_test.c
> > index 3aaaf47fa4ee2..dc766055aa594 100644
> > --- a/drivers/misc/pci_endpoint_test.c
> > +++ b/drivers/misc/pci_endpoint_test.c
> > @@ -42,6 +42,8 @@
> >  #define COMMAND_READ				BIT(3)
> >  #define COMMAND_WRITE				BIT(4)
> >  #define COMMAND_COPY				BIT(5)
> > +#define COMMAND_ENABLE_DOORBELL			BIT(6)
> > +#define COMMAND_DISABLE_DOORBELL		BIT(7)
> >
> >  #define PCI_ENDPOINT_TEST_STATUS		0x8
> >  #define STATUS_READ_SUCCESS			BIT(0)
> > @@ -53,6 +55,11 @@
> >  #define STATUS_IRQ_RAISED			BIT(6)
> >  #define STATUS_SRC_ADDR_INVALID			BIT(7)
> >  #define STATUS_DST_ADDR_INVALID			BIT(8)
> > +#define STATUS_DOORBELL_SUCCESS			BIT(9)
> > +#define STATUS_DOORBELL_ENABLE_SUCCESS		BIT(10)
> > +#define STATUS_DOORBELL_ENABLE_FAIL		BIT(11)
> > +#define STATUS_DOORBELL_DISABLE_SUCCESS		BIT(12)
> > +#define STATUS_DOORBELL_DISABLE_FAIL		BIT(13)
> >
> >  #define PCI_ENDPOINT_TEST_LOWER_SRC_ADDR	0x0c
> >  #define PCI_ENDPOINT_TEST_UPPER_SRC_ADDR	0x10
> > @@ -67,6 +74,10 @@
> >  #define PCI_ENDPOINT_TEST_IRQ_NUMBER		0x28
> >
> >  #define PCI_ENDPOINT_TEST_FLAGS			0x2c
> > +#define PCI_ENDPOINT_TEST_DB_BAR		0x30
> > +#define PCI_ENDPOINT_TEST_DB_OFFSET		0x34
> > +#define PCI_ENDPOINT_TEST_DB_DATA		0x38
> > +
> >  #define FLAG_USE_DMA				BIT(0)
> >
> >  #define PCI_DEVICE_ID_TI_AM654			0xb00c
> > @@ -108,6 +119,7 @@ enum pci_barno {
> >  	BAR_3,
> >  	BAR_4,
> >  	BAR_5,
> > +	NO_BAR = -1,
>
> I really hate duplicating this enum definition both in EPF driver and here.
> Maybe we should move this to pci.h?

Yes, It is not related this patch. It should belong clean up patch. We
can do it later.

>
> >  };
> >
> >  struct pci_endpoint_test {
> > @@ -746,6 +758,62 @@ static bool pci_endpoint_test_set_irq(struct pci_endpoint_test *test,
> >  	return false;
> >  }
> >
> > +static bool pci_endpoint_test_doorbell(struct pci_endpoint_test *test)
> > +{
> > +	struct pci_dev *pdev = test->pdev;
> > +	struct device *dev = &pdev->dev;
> > +	int irq_type = test->irq_type;
> > +	enum pci_barno bar;
> > +	u32 data, status;
> > +	u32 addr;
> > +
> > +	if (irq_type < IRQ_TYPE_INTX || irq_type > IRQ_TYPE_MSIX) {
> > +		dev_err(dev, "Invalid IRQ type option\n");
> > +		return false;
> > +	}
>
> Is this check necessary?

Suppose yes, it pass down from RC driver side, we should not suppose it
alwasy do correct things.

>
> > +
> > +	pci_endpoint_test_writel(test, PCI_ENDPOINT_TEST_IRQ_TYPE, irq_type);
> > +	pci_endpoint_test_writel(test, PCI_ENDPOINT_TEST_IRQ_NUMBER, 1);
> > +	pci_endpoint_test_writel(test, PCI_ENDPOINT_TEST_COMMAND,
> > +				 COMMAND_ENABLE_DOORBELL);
> > +
> > +	wait_for_completion_timeout(&test->irq_raised, msecs_to_jiffies(1000));
> > +
> > +	status = pci_endpoint_test_readl(test, PCI_ENDPOINT_TEST_STATUS);
> > +	if (status & STATUS_DOORBELL_ENABLE_FAIL)
> > +		return false;
>
> I think we should add a error print here and below.
>
> > +
> > +	data = pci_endpoint_test_readl(test, PCI_ENDPOINT_TEST_DB_DATA);
> > +	addr = pci_endpoint_test_readl(test, PCI_ENDPOINT_TEST_DB_OFFSET);
> > +	bar = pci_endpoint_test_readl(test, PCI_ENDPOINT_TEST_DB_BAR);
> > +
> > +	pci_endpoint_test_writel(test, PCI_ENDPOINT_TEST_IRQ_TYPE, irq_type);
> > +	pci_endpoint_test_writel(test, PCI_ENDPOINT_TEST_IRQ_NUMBER, 1);
> > +
> > +	pci_endpoint_test_writel(test, PCI_ENDPOINT_TEST_STATUS, 0);
> > +
> > +	bar = pci_endpoint_test_readl(test, PCI_ENDPOINT_TEST_DB_BAR);
> > +
> > +	writel(data, test->bar[bar] + addr);
> > +
> > +	wait_for_completion_timeout(&test->irq_raised, msecs_to_jiffies(1000));
> > +
> > +	status = pci_endpoint_test_readl(test, PCI_ENDPOINT_TEST_STATUS);
> > +
> > +	pci_endpoint_test_writel(test, PCI_ENDPOINT_TEST_COMMAND,
> > +				 COMMAND_DISABLE_DOORBELL);
> > +
> > +	wait_for_completion_timeout(&test->irq_raised, msecs_to_jiffies(1000));
> > +
> > +	status |= pci_endpoint_test_readl(test, PCI_ENDPOINT_TEST_STATUS);
> > +
> > +	if ((status & STATUS_DOORBELL_SUCCESS) &&
> > +	    (status & STATUS_DOORBELL_DISABLE_SUCCESS))
> > +		return true;
>
> Usual convention is to check for error and return true at the end.
>
> > +
> > +	return false;
> > +}
> > +
> >  static long pci_endpoint_test_ioctl(struct file *file, unsigned int cmd,
> >  				    unsigned long arg)
> >  {
> > @@ -793,6 +861,9 @@ static long pci_endpoint_test_ioctl(struct file *file, unsigned int cmd,
> >  	case PCITEST_CLEAR_IRQ:
> >  		ret = pci_endpoint_test_clear_irq(test);
> >  		break;
> > +	case PCITEST_DOORBELL:
> > +		ret = pci_endpoint_test_doorbell(test);
> > +		break;
> >  	}
> >
> >  ret:
> > diff --git a/include/uapi/linux/pcitest.h b/include/uapi/linux/pcitest.h
> > index 94b46b043b536..06d9f548b510e 100644
> > --- a/include/uapi/linux/pcitest.h
> > +++ b/include/uapi/linux/pcitest.h
> > @@ -21,6 +21,7 @@
> >  #define PCITEST_SET_IRQTYPE	_IOW('P', 0x8, int)
> >  #define PCITEST_GET_IRQTYPE	_IO('P', 0x9)
> >  #define PCITEST_CLEAR_IRQ	_IO('P', 0x10)
> > +#define PCITEST_DOORBELL	_IO('P', 0x11)
>
> I think defining PCITEST_CLEAR_IRQ as 0x10 was a mistake. It should've been 0xa.
> But since it is a uapi, we cannot change it. Atleast add new ones starting from
> 0xa.
>

Yes, thanks.

> Niklas's consecutive BAR patch adds a new ioctl for 0xa, but we can fix the
> conflict later depending on which patch gets merged first.
>
> - Mani
>
> --
> மணிவண்ணன் சதாசிவம்