linux-kernel - Re: [PATCH v2 3/5] PCI: endpoint: pci-epf-test: add doorbell test

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Date:   Fri, 29 Sep 2023 10:26:25 -0400
From:   Frank Li <Frank.li@....com>
To:     Kishon Vijay Abraham I <kvijayab@....com>
Cc:     manivannan.sadhasivam@...aro.org, aisheng.dong@....com,
        bhelgaas@...gle.com, devicetree@...r.kernel.org,
        festevam@...il.com, imx@...ts.linux.dev, jdmason@...zu.us,
        kernel@...gutronix.de, kishon@...nel.org, kw@...ux.com,
        linux-arm-kernel@...ts.infradead.org, linux-imx@....com,
        linux-kernel@...r.kernel.org, linux-pci@...r.kernel.org,
        lorenzo.pieralisi@....com, lpieralisi@...nel.org, maz@...nel.org,
        s.hauer@...gutronix.de, shawnguo@...nel.org, tglx@...utronix.de
Subject: Re: [PATCH v2 3/5] PCI: endpoint: pci-epf-test: add doorbell test

On Fri, Sep 29, 2023 at 03:03:35PM +0530, Kishon Vijay Abraham I wrote:
> Hi Frank,
> 
> On 9/12/2023 3:39 AM, Frank Li wrote:
> > Add three register: doorbell_bar, doorbell_addr, doorbell_data,
> > doorbell_done. Call pci_epf_alloc_doorbell() all a doorbell address space.
> > 
> > Root complex(RC) side driver can trigger pci-epc-test's doorbell callback
> > handler by write doorbell_data to mapped doorbell_bar's address space.
> > 
> > pci-epc-test will set doorbell_done in doorbell callback.
> > 
> > Signed-off-by: Frank Li <Frank.Li@....com>
> > ---
> >   drivers/pci/endpoint/functions/pci-epf-test.c | 59 ++++++++++++++++++-
> >   1 file changed, 58 insertions(+), 1 deletion(-)
> > 
> > diff --git a/drivers/pci/endpoint/functions/pci-epf-test.c b/drivers/pci/endpoint/functions/pci-epf-test.c
> > index 1f0d2b84296a3..566549919b87b 100644
> > --- a/drivers/pci/endpoint/functions/pci-epf-test.c
> > +++ b/drivers/pci/endpoint/functions/pci-epf-test.c
> > @@ -11,6 +11,7 @@
> >   #include <linux/dmaengine.h>
> >   #include <linux/io.h>
> >   #include <linux/module.h>
> > +#include <linux/msi.h>
> >   #include <linux/slab.h>
> >   #include <linux/pci_ids.h>
> >   #include <linux/random.h>
> > @@ -39,17 +40,21 @@
> >   #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 FLAG_USE_DMA			BIT(0)
> >   #define TIMER_RESOLUTION		1
> > +#define MAGIC_VERSION_MASK		GENMASK(7, 0)
> > +
> >   static struct workqueue_struct *kpcitest_workqueue;
> >   struct pci_epf_test {
> >   	void			*reg[PCI_STD_NUM_BARS];
> >   	struct pci_epf		*epf;
> >   	enum pci_barno		test_reg_bar;
> > +	enum pci_barno		doorbell_bar;
> >   	size_t			msix_table_offset;
> >   	struct delayed_work	cmd_handler;
> >   	struct dma_chan		*dma_chan_tx;
> > @@ -74,6 +79,9 @@ struct pci_epf_test_reg {
> >   	u32	irq_type;
> >   	u32	irq_number;
> >   	u32	flags;
> > +	u32	doorbell_bar;
> 
> You could extend test_reg_bar for doorbell to avoid using additional BAR.

It is sperated physical address space. So far, epc still not support map
two difference physcial address space into a bar.

So I have to use a sperate pci bar for doorbell.

Frank

> 
> 
> > +	u32	doorbell_addr;
> > +	u32	doorbell_data;
> >   } __packed;
> 
> Thanks,
> Kishon