Date:   Tue, 9 Aug 2022 23:07:18 +0300
From:   Serge Semin <fancer.lancer@...il.com>
To:     Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>
Cc:     Serge Semin <Sergey.Semin@...kalelectronics.ru>,
        Rob Herring <robh@...nel.org>,
        Bjorn Helgaas <bhelgaas@...gle.com>,
        Lorenzo Pieralisi <lorenzo.pieralisi@....com>,
        Jingoo Han <jingoohan1@...il.com>,
        Gustavo Pimentel <gustavo.pimentel@...opsys.com>,
        Lorenzo Pieralisi <lpieralisi@...nel.org>,
        Krzysztof Wilczyński <kw@...ux.com>,
        Alexey Malahov <Alexey.Malahov@...kalelectronics.ru>,
        Pavel Parkhomenko <Pavel.Parkhomenko@...kalelectronics.ru>,
        Frank Li <Frank.Li@....com>, Rob Herring <robh+dt@...nel.org>,
        linux-pci@...r.kernel.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH RESEND v4 15/15] PCI: dwc: Introduce dma-ranges property
 support for RC-host

On Mon, Aug 01, 2022 at 07:30:47PM +0530, Manivannan Sadhasivam wrote:
> On Fri, Jun 24, 2022 at 05:39:47PM +0300, Serge Semin wrote:
> > In accordance with the generic PCIe Root Port DT-bindings the "dma-ranges"
> > property has the same format as the "ranges" property. The only difference
> > is in their semantics. The "dma-ranges" property describes the PCIe-to-CPU
> > memory mapping in opposite to the CPU-to-PCIe mapping of the "ranges"
> > property. Even though the DW PCIe controllers are normally equipped with
> > the internal Address Translation Unit which inbound and outbound tables
> > can be used to implement both properties semantics, it was surprising for
> > me to discover that the host-related part of the DW PCIe driver currently
> > supports the "ranges" property only while the "dma-ranges" windows are
> > just ignored. Having the "dma-ranges" supported in the driver would be
> > very handy for the platforms, that don't tolerate the 1:1 CPU-PCIe memory
> > mapping and require a customized PCIe memory layout. So let's fix that by
> > introducing the "dma-ranges" property support.
> > 
> > First of all we suggest to rename the dw_pcie_prog_inbound_atu() method to
> > dw_pcie_prog_ep_inbound_atu() and create a new version of the
> > dw_pcie_prog_inbound_atu() function. Thus we'll have two methods for the
> > RC and EP controllers respectively in the same way as it has been
> > developed for the outbound ATU setup methods.
> > 
> > Secondly aside with the memory window index and type the new
> > dw_pcie_prog_inbound_atu() function will accept CPU address, PCIe address
> > and size as its arguments. These parameters define the PCIe and CPU memory
> > ranges which will be used to setup the respective inbound ATU mapping. The
> > passed parameters need to be verified against the ATU ranges constraints
> > in the same way as it is done for the outbound ranges.
> > 
> > Finally the DMA-ranges detected for the PCIe controller need to be
> > converted to the inbound ATU entries during the host controller
> > initialization procedure. It will be done in the framework of the
> > dw_pcie_iatu_setup() method. Note before setting the inbound ranges up we
> > need to disable all the inbound ATU entries in order to prevent unexpected
> > PCIe TLPs translations defined by some third party software like
> > bootloaders.
> > 
> > Signed-off-by: Serge Semin <Sergey.Semin@...kalelectronics.ru>
> 
> Small nitpick below,
> 
> Reviewed-by: Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>
> 
> Thanks,
> Mani
> 
> > Reviewed-by: Rob Herring <robh@...nel.org>
> > 
> > ---
> > 
> > Changelog v3:
> > - Drop inbound iATU window size alignment constraint. (@Manivannan)
> > ---
> >  .../pci/controller/dwc/pcie-designware-ep.c   |  4 +-
> >  .../pci/controller/dwc/pcie-designware-host.c | 32 ++++++++++-
> >  drivers/pci/controller/dwc/pcie-designware.c  | 56 ++++++++++++++++++-
> >  drivers/pci/controller/dwc/pcie-designware.h  |  6 +-
> >  4 files changed, 89 insertions(+), 9 deletions(-)
> > 
> > diff --git a/drivers/pci/controller/dwc/pcie-designware-ep.c b/drivers/pci/controller/dwc/pcie-designware-ep.c
> > index 627c4b69878c..441feff1917a 100644
> > --- a/drivers/pci/controller/dwc/pcie-designware-ep.c
> > +++ b/drivers/pci/controller/dwc/pcie-designware-ep.c
> > @@ -167,8 +167,8 @@ static int dw_pcie_ep_inbound_atu(struct dw_pcie_ep *ep, u8 func_no, int type,
> >  		return -EINVAL;
> >  	}
> >  
> > -	ret = dw_pcie_prog_inbound_atu(pci, func_no, free_win, type,
> > -				       cpu_addr, bar);
> > +	ret = dw_pcie_prog_ep_inbound_atu(pci, func_no, free_win, type,
> > +					  cpu_addr, bar);
> >  	if (ret < 0) {
> >  		dev_err(pci->dev, "Failed to program IB window\n");
> >  		return ret;
> > diff --git a/drivers/pci/controller/dwc/pcie-designware-host.c b/drivers/pci/controller/dwc/pcie-designware-host.c
> > index 6993ce9e856d..2fbe9dc11634 100644
> > --- a/drivers/pci/controller/dwc/pcie-designware-host.c
> > +++ b/drivers/pci/controller/dwc/pcie-designware-host.c
> > @@ -581,12 +581,15 @@ static int dw_pcie_iatu_setup(struct dw_pcie_rp *pp)
> >  	}
> >  
> >  	/*
> > -	 * Ensure all outbound windows are disabled before proceeding with
> > -	 * the MEM/IO ranges setups.
> > +	 * Ensure all out/inbound windows are disabled before proceeding with
> > +	 * the MEM/IO (dma-)ranges setups.
> >  	 */
> >  	for (i = 0; i < pci->num_ob_windows; i++)
> >  		dw_pcie_disable_atu(pci, PCIE_ATU_REGION_DIR_OB, i);
> >  
> > +	for (i = 0; i < pci->num_ib_windows; i++)
> > +		dw_pcie_disable_atu(pci, PCIE_ATU_REGION_DIR_IB, i);
> > +
> >  	i = 0;
> >  	resource_list_for_each_entry(entry, &pp->bridge->windows) {
> >  		if (resource_type(entry->res) != IORESOURCE_MEM)
> > @@ -623,9 +626,32 @@ static int dw_pcie_iatu_setup(struct dw_pcie_rp *pp)
> >  	}
> >  
> >  	if (pci->num_ob_windows <= i)
> > -		dev_warn(pci->dev, "Resources exceed number of ATU entries (%d)\n",
> > +		dev_warn(pci->dev, "Ranges exceed outbound iATU size (%d)\n",
> >  			 pci->num_ob_windows);
> >  
> 

> I think a comment here explaining what's going on below would be helpful in the
> future.

Both ranges and dma-ranges are initialized in the same way. Moreover
the method is pretty much coherent with self-explained name. So adding
an additional comment here doesn't seem much required.

> 
> > +	i = 0;
> > +	resource_list_for_each_entry(entry, &pp->bridge->dma_ranges) {
> > +		if (resource_type(entry->res) != IORESOURCE_MEM)
> > +			continue;
> > +
> > +		if (pci->num_ib_windows <= i)
> > +			break;
> > +
> > +		ret = dw_pcie_prog_inbound_atu(pci, i++, PCIE_ATU_TYPE_MEM,
> > +					       entry->res->start,
> > +					       entry->res->start - entry->offset,
> > +					       resource_size(entry->res));
> > +		if (ret) {
> > +			dev_err(pci->dev, "Failed to set DMA range %pr\n",
> > +				entry->res);
> > +			return ret;
> > +		}
> > +	}
> > +
> > +	if (pci->num_ib_windows <= i)
> > +		dev_warn(pci->dev, "Dma-ranges exceed inbound iATU size (%u)\n",
> 

> "dma-ranges"

I was referring to the similar message printed in case of the number
of specified ranges goes out of bounds.

-Sergey

> 
> > +			 pci->num_ib_windows);
> > +
> >  	return 0;
> >  }
> >  
> > diff --git a/drivers/pci/controller/dwc/pcie-designware.c b/drivers/pci/controller/dwc/pcie-designware.c
> > index 9c622b635fdd..7a5be3c4f8e0 100644
> > --- a/drivers/pci/controller/dwc/pcie-designware.c
> > +++ b/drivers/pci/controller/dwc/pcie-designware.c
> > @@ -396,8 +396,60 @@ static inline void dw_pcie_writel_atu_ib(struct dw_pcie *pci, u32 index, u32 reg
> >  	dw_pcie_writel_atu(pci, PCIE_ATU_REGION_DIR_IB, index, reg, val);
> >  }
> >  
> > -int dw_pcie_prog_inbound_atu(struct dw_pcie *pci, u8 func_no, int index,
> > -			     int type, u64 cpu_addr, u8 bar)
> > +int dw_pcie_prog_inbound_atu(struct dw_pcie *pci, int index, int type,
> > +			     u64 cpu_addr, u64 pci_addr, u64 size)
> > +{
> > +	u64 limit_addr = pci_addr + size - 1;
> > +	u32 retries, val;
> > +
> > +	if ((limit_addr & ~pci->region_limit) != (pci_addr & ~pci->region_limit) ||
> > +	    !IS_ALIGNED(cpu_addr, pci->region_align) ||
> > +	    !IS_ALIGNED(pci_addr, pci->region_align) || !size) {
> > +		return -EINVAL;
> > +	}
> > +
> > +	dw_pcie_writel_atu_ib(pci, index, PCIE_ATU_LOWER_BASE,
> > +			      lower_32_bits(pci_addr));
> > +	dw_pcie_writel_atu_ib(pci, index, PCIE_ATU_UPPER_BASE,
> > +			      upper_32_bits(pci_addr));
> > +
> > +	dw_pcie_writel_atu_ib(pci, index, PCIE_ATU_LIMIT,
> > +			      lower_32_bits(limit_addr));
> > +	if (dw_pcie_ver_is_ge(pci, 460A))
> > +		dw_pcie_writel_atu_ib(pci, index, PCIE_ATU_UPPER_LIMIT,
> > +				      upper_32_bits(limit_addr));
> > +
> > +	dw_pcie_writel_atu_ib(pci, index, PCIE_ATU_LOWER_TARGET,
> > +			      lower_32_bits(cpu_addr));
> > +	dw_pcie_writel_atu_ib(pci, index, PCIE_ATU_UPPER_TARGET,
> > +			      upper_32_bits(cpu_addr));
> > +
> > +	val = type;
> > +	if (upper_32_bits(limit_addr) > upper_32_bits(pci_addr) &&
> > +	    dw_pcie_ver_is_ge(pci, 460A))
> > +		val |= PCIE_ATU_INCREASE_REGION_SIZE;
> > +	dw_pcie_writel_atu_ib(pci, index, PCIE_ATU_REGION_CTRL1, val);
> > +	dw_pcie_writel_atu_ib(pci, index, PCIE_ATU_REGION_CTRL2, PCIE_ATU_ENABLE);
> > +
> > +	/*
> > +	 * Make sure ATU enable takes effect before any subsequent config
> > +	 * and I/O accesses.
> > +	 */
> > +	for (retries = 0; retries < LINK_WAIT_MAX_IATU_RETRIES; retries++) {
> > +		val = dw_pcie_readl_atu_ib(pci, index, PCIE_ATU_REGION_CTRL2);
> > +		if (val & PCIE_ATU_ENABLE)
> > +			return 0;
> > +
> > +		mdelay(LINK_WAIT_IATU);
> > +	}
> > +
> > +	dev_err(pci->dev, "Inbound iATU is not being enabled\n");
> > +
> > +	return -ETIMEDOUT;
> > +}
> > +
> > +int dw_pcie_prog_ep_inbound_atu(struct dw_pcie *pci, u8 func_no, int index,
> > +				int type, u64 cpu_addr, u8 bar)
> >  {
> >  	u32 retries, val;
> >  
> > diff --git a/drivers/pci/controller/dwc/pcie-designware.h b/drivers/pci/controller/dwc/pcie-designware.h
> > index c3e73ed9aff5..5954e8cf9eec 100644
> > --- a/drivers/pci/controller/dwc/pcie-designware.h
> > +++ b/drivers/pci/controller/dwc/pcie-designware.h
> > @@ -308,8 +308,10 @@ int dw_pcie_prog_outbound_atu(struct dw_pcie *pci, int index, int type,
> >  			      u64 cpu_addr, u64 pci_addr, u64 size);
> >  int dw_pcie_prog_ep_outbound_atu(struct dw_pcie *pci, u8 func_no, int index,
> >  				 int type, u64 cpu_addr, u64 pci_addr, u64 size);
> > -int dw_pcie_prog_inbound_atu(struct dw_pcie *pci, u8 func_no, int index,
> > -			     int type, u64 cpu_addr, u8 bar);
> > +int dw_pcie_prog_inbound_atu(struct dw_pcie *pci, int index, int type,
> > +			     u64 cpu_addr, u64 pci_addr, u64 size);
> > +int dw_pcie_prog_ep_inbound_atu(struct dw_pcie *pci, u8 func_no, int index,
> > +				int type, u64 cpu_addr, u8 bar);
> >  void dw_pcie_disable_atu(struct dw_pcie *pci, u32 dir, int index);
> >  void dw_pcie_setup(struct dw_pcie *pci);
> >  void dw_pcie_iatu_detect(struct dw_pcie *pci);
> > -- 
> > 2.35.1
> > 
> 
> -- 
> மணிவண்ணன் சதாசிவம்

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