RE: [PATCH v3 1/2] PCI: xilinx-nwl: Enable coherent PCIe DMA traffic using CCI

[Bharat Kumar Gogada <bharatku@xilinx.com>]

Ping.

> -----Original Message-----
> From: Bharat Kumar Gogada
> Sent: Monday, March 15, 2021 11:43 AM
> To: Bharat Kumar Gogada <bharat.kumar.gogada@xilinx.com>; linux-
> pci@vger.kernel.org; linux-kernel@vger.kernel.org
> Cc: bhelgaas@google.com
> Subject: RE: [PATCH v3 1/2] PCI: xilinx-nwl: Enable coherent PCIe DMA traffic
> using CCI
> 
> Ping.
> 
> > -----Original Message-----
> > From: Bharat Kumar Gogada <bharat.kumar.gogada@xilinx.com>
> > Sent: Monday, February 22, 2021 2:18 PM
> > To: linux-pci@vger.kernel.org; linux-kernel@vger.kernel.org
> > Cc: bhelgaas@google.com; Bharat Kumar Gogada <bharatku@xilinx.com>
> > Subject: [PATCH v3 1/2] PCI: xilinx-nwl: Enable coherent PCIe DMA
> > traffic using CCI
> >
> > Add support for routing PCIe DMA traffic coherently when Cache
> > Coherent Interconnect (CCI) is enabled in the system.
> > The "dma-coherent" property is used to determine if CCI is enabled or not.
> > Refer to https://developer.arm.com/documentation/ddi0470/k/preface
> > for the CCI specification.
> >
> > Signed-off-by: Bharat Kumar Gogada <bharat.kumar.gogada@xilinx.com>
> > ---
> >  drivers/pci/controller/pcie-xilinx-nwl.c | 7 +++++++
> >  1 file changed, 7 insertions(+)
> >
> > diff --git a/drivers/pci/controller/pcie-xilinx-nwl.c
> > b/drivers/pci/controller/pcie-xilinx-nwl.c
> > index 07e36661bbc2..8689311c5ef6 100644
> > --- a/drivers/pci/controller/pcie-xilinx-nwl.c
> > +++ b/drivers/pci/controller/pcie-xilinx-nwl.c
> > @@ -26,6 +26,7 @@
> >
> >  /* Bridge core config registers */
> >  #define BRCFG_PCIE_RX0			0x00000000
> > +#define BRCFG_PCIE_RX1			0x00000004
> >  #define BRCFG_INTERRUPT			0x00000010
> >  #define BRCFG_PCIE_RX_MSG_FILTER	0x00000020
> >
> > @@ -128,6 +129,7 @@
> >  #define NWL_ECAM_VALUE_DEFAULT		12
> >
> >  #define CFG_DMA_REG_BAR			GENMASK(2, 0)
> > +#define CFG_PCIE_CACHE			GENMASK(7, 0)
> >
> >  #define INT_PCI_MSI_NR			(2 * 32)
> >
> > @@ -675,6 +677,11 @@ static int nwl_pcie_bridge_init(struct nwl_pcie
> > *pcie)
> >  	nwl_bridge_writel(pcie, CFG_ENABLE_MSG_FILTER_MASK,
> >  			  BRCFG_PCIE_RX_MSG_FILTER);
> >
> > +	/* This routes the PCIe DMA traffic to go through CCI path */
> > +	if (of_dma_is_coherent(dev->of_node))
> > +		nwl_bridge_writel(pcie, nwl_bridge_readl(pcie,
> > BRCFG_PCIE_RX1) |
> > +				  CFG_PCIE_CACHE, BRCFG_PCIE_RX1);
> > +
> >  	err = nwl_wait_for_link(pcie);
> >  	if (err)
> >  		return err;
> > --
> > 2.17.1