Re: [PATCH v4 4/4] PCI: qcom: Enable ECAM feature

Manivannan Sadhasivam
2025-02-10T09:47:16Z

On Mon, Feb 10, 2025 at 03:04:43PM +0530, Krishna Chaitanya Chundru wrote:
>
>
> On 2/10/2025 2:52 PM, Manivannan Sadhasivam wrote:
> > On Fri, Feb 07, 2025 at 04:58:59AM +0530, Krishna Chaitanya Chundru wrote:
> > > The ELBI registers falls after the DBI space, PARF_SLV_DBI_ELBI register
> > > gives us the offset from which ELBI starts. so use this offset and cfg
> > > win to map these regions instead of doing the ioremap again.
> > >
> > > On root bus, we have only the root port. Any access other than that
> > > should not go out of the link and should return all F's. Since the iATU
> > > is configured for the buses which starts after root bus, block the
> > > transactions starting from function 1 of the root bus to the end of
> > > the root bus (i.e from dbi_base + 4kb to dbi_base + 1MB) from going
> > > outside the link through ECAM blocker through PARF registers.
> > >
> > > Signed-off-by: Krishna Chaitanya Chundru <krishna.chundru@oss.qualcomm.com>
> > > ---
> > > drivers/pci/controller/dwc/pcie-qcom.c | 77 ++++++++++++++++++++++++++++++++--
> > > 1 file changed, 73 insertions(+), 4 deletions(-)
> > >
> > > diff --git a/drivers/pci/controller/dwc/pcie-qcom.c b/drivers/pci/controller/dwc/pcie-qcom.c
> > > index e4d3366ead1f..84297b308e7e 100644
> > > --- a/drivers/pci/controller/dwc/pcie-qcom.c
> > > +++ b/drivers/pci/controller/dwc/pcie-qcom.c
> > > @@ -52,6 +52,7 @@
> > > #define PARF_AXI_MSTR_WR_ADDR_HALT_V2 0x1a8
> > > #define PARF_Q2A_FLUSH 0x1ac
> > > #define PARF_LTSSM 0x1b0
> > > +#define PARF_SLV_DBI_ELBI 0x1b4
> > > #define PARF_INT_ALL_STATUS 0x224
> > > #define PARF_INT_ALL_CLEAR 0x228
> > > #define PARF_INT_ALL_MASK 0x22c
> > > @@ -61,6 +62,17 @@
> > > #define PARF_DBI_BASE_ADDR_V2_HI 0x354
> > > #define PARF_SLV_ADDR_SPACE_SIZE_V2 0x358
> > > #define PARF_SLV_ADDR_SPACE_SIZE_V2_HI 0x35c
> > > +#define PARF_BLOCK_SLV_AXI_WR_BASE 0x360
> > > +#define PARF_BLOCK_SLV_AXI_WR_BASE_HI 0x364
> > > +#define PARF_BLOCK_SLV_AXI_WR_LIMIT 0x368
> > > +#define PARF_BLOCK_SLV_AXI_WR_LIMIT_HI 0x36c
> > > +#define PARF_BLOCK_SLV_AXI_RD_BASE 0x370
> > > +#define PARF_BLOCK_SLV_AXI_RD_BASE_HI 0x374
> > > +#define PARF_BLOCK_SLV_AXI_RD_LIMIT 0x378
> > > +#define PARF_BLOCK_SLV_AXI_RD_LIMIT_HI 0x37c
> > > +#define PARF_ECAM_BASE 0x380
> > > +#define PARF_ECAM_BASE_HI 0x384
> > > +
> > > #define PARF_NO_SNOOP_OVERIDE 0x3d4
> > > #define PARF_ATU_BASE_ADDR 0x634
> > > #define PARF_ATU_BASE_ADDR_HI 0x638
> > > @@ -84,6 +96,7 @@
> > > /* PARF_SYS_CTRL register fields */
> > > #define MAC_PHY_POWERDOWN_IN_P2_D_MUX_EN BIT(29)
> > > +#define PCIE_ECAM_BLOCKER_EN BIT(26)
> > > #define MST_WAKEUP_EN BIT(13)
> > > #define SLV_WAKEUP_EN BIT(12)
> > > #define MSTR_ACLK_CGC_DIS BIT(10)
> > > @@ -294,6 +307,44 @@ static void qcom_ep_reset_deassert(struct qcom_pcie *pcie)
> > > usleep_range(PERST_DELAY_US, PERST_DELAY_US + 500);
> > > }
> > > +static void qcom_pci_config_ecam(struct dw_pcie_rp *pp)
> > > +{
> > > + struct dw_pcie *pci = to_dw_pcie_from_pp(pp);
> > > + struct qcom_pcie *pcie = to_qcom_pcie(pci);
> > > + u64 addr, addr_end;
> > > + u32 val;
> > > +
> > > + /* Set the ECAM base */
> > > + writel_relaxed(lower_32_bits(pci->dbi_phys_addr), pcie->parf + PARF_ECAM_BASE);
> > > + writel_relaxed(upper_32_bits(pci->dbi_phys_addr), pcie->parf + PARF_ECAM_BASE_HI);
> > > +
> > > + /*
> > > + * The only device on root bus is the Root Port. Any access other than that
> > > + * should not go out of the link and should return all F's. Since the iATU
> > > + * is configured for the buses which starts after root bus, block the transactions
> > > + * starting from function 1 of the root bus to the end of the root bus (i.e from
> > > + * dbi_base + 4kb to dbi_base + 1MB) from going outside the link.
> > > + */
> > > + addr = pci->dbi_phys_addr + SZ_4K;
> > > + writel_relaxed(lower_32_bits(addr), pcie->parf + PARF_BLOCK_SLV_AXI_WR_BASE);
> > > + writel_relaxed(upper_32_bits(addr), pcie->parf + PARF_BLOCK_SLV_AXI_WR_BASE_HI);
> > > +
> > > + writel_relaxed(lower_32_bits(addr), pcie->parf + PARF_BLOCK_SLV_AXI_RD_BASE);
> > > + writel_relaxed(upper_32_bits(addr), pcie->parf + PARF_BLOCK_SLV_AXI_RD_BASE_HI);
> > > +
> > > + addr_end = pci->dbi_phys_addr + SZ_1M - 1;
> > > +
> > > + writel_relaxed(lower_32_bits(addr_end), pcie->parf + PARF_BLOCK_SLV_AXI_WR_LIMIT);
> > > + writel_relaxed(upper_32_bits(addr_end), pcie->parf + PARF_BLOCK_SLV_AXI_WR_LIMIT_HI);
> > > +
> > > + writel_relaxed(lower_32_bits(addr_end), pcie->parf + PARF_BLOCK_SLV_AXI_RD_LIMIT);
> > > + writel_relaxed(upper_32_bits(addr_end), pcie->parf + PARF_BLOCK_SLV_AXI_RD_LIMIT_HI);
> > > +
> > > + val = readl_relaxed(pcie->parf + PARF_SYS_CTRL);
> > > + val |= PCIE_ECAM_BLOCKER_EN;
> > > + writel_relaxed(val, pcie->parf + PARF_SYS_CTRL);
> > > +}
> > > +
> > > static int qcom_pcie_start_link(struct dw_pcie *pci)
> > > {
> > > struct qcom_pcie *pcie = to_qcom_pcie(pci);
> > > @@ -303,6 +354,9 @@ static int qcom_pcie_start_link(struct dw_pcie *pci)
> > > qcom_pcie_common_set_16gt_lane_margining(pci);
> > > }
> > > + if (pci->pp.ecam_mode)
> > > + qcom_pci_config_ecam(&pci->pp);
> > > +
> > > /* Enable Link Training state machine */
> > > if (pcie->cfg->ops->ltssm_enable)
> > > pcie->cfg->ops->ltssm_enable(pcie);
> > > @@ -1233,6 +1287,7 @@ static int qcom_pcie_host_init(struct dw_pcie_rp *pp)
> > > {
> > > struct dw_pcie *pci = to_dw_pcie_from_pp(pp);
> > > struct qcom_pcie *pcie = to_qcom_pcie(pci);
> > > + u16 offset;
> > > int ret;
> > > qcom_ep_reset_assert(pcie);
> > > @@ -1241,6 +1296,11 @@ static int qcom_pcie_host_init(struct dw_pcie_rp *pp)
> > > if (ret)
> > > return ret;
> > > + if (pp->ecam_mode) {
> > > + offset = readl(pcie->parf + PARF_SLV_DBI_ELBI);
> > > + pcie->elbi = pci->dbi_base + offset;
> > > + }
> >
> > If you use the existing 'elbi' register offset defined in DT, you can just rely
> > on the DWC core to call dw_pcie_ecam_supported() as I mentioned in my comment in
> > patch 3.
> > >> +
> > > ret = phy_set_mode_ext(pcie->phy, PHY_MODE_PCIE, PHY_MODE_PCIE_RC);
> > > if (ret)
> > > goto err_deinit;
> > > @@ -1615,6 +1675,13 @@ static int qcom_pcie_probe(struct platform_device *pdev)
> > > pci->ops = &dw_pcie_ops;
> > > pp = &pci->pp;
> > > + pp->bridge = devm_pci_alloc_host_bridge(dev, 0);
> > > + if (!pp->bridge) {
> > > + ret = -ENOMEM;
> > > + goto err_pm_runtime_put;
> > > + }
> > > +
> >
> > This will also go away.
> >
> Hi Mani,
>
> I get your point but the problem is in ECAM mode the DBI address to maximum
> of 256 MB will be ioremap by pci_ecam_create(). If we don't skip
> this ioremap of elbi ioremap in pci_ecam_create because we already
> iormaped elbi which falls in dbi address to 256 MB region( as we can't
> remap same region twice). so we need to skip doing ioremap for elbi
> region.
>

Then obviously, your DT entries are wrong. You cannot define overlapping regions
on purpose. Can't you leave the ELBI region and start the config region?

- Mani

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