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Date: Wed, 17 Jun 2020 13:28:12 -0400
From: Jim Quinlan <james.quinlan@...adcom.com>
To: Bjorn Helgaas <helgaas@...nel.org>
Cc: "open list:PCI NATIVE HOST BRIDGE AND ENDPOINT DRIVERS"
<linux-pci@...r.kernel.org>, Christoph Hellwig <hch@....de>,
Nicolas Saenz Julienne <nsaenzjulienne@...e.de>,
"maintainer:BROADCOM BCM7XXX ARM ARCHITECTURE"
<bcm-kernel-feedback-list@...adcom.com>,
Lorenzo Pieralisi <lorenzo.pieralisi@....com>,
Rob Herring <robh@...nel.org>,
Bjorn Helgaas <bhelgaas@...gle.com>,
Florian Fainelli <f.fainelli@...il.com>,
"moderated list:BROADCOM BCM2711/BCM2835 ARM ARCHITECTURE"
<linux-rpi-kernel@...ts.infradead.org>,
"moderated list:BROADCOM BCM2711/BCM2835 ARM ARCHITECTURE"
<linux-arm-kernel@...ts.infradead.org>,
open list <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v5 09/12] PCI: brcmstb: Set internal memory viewport sizes
Hello Bjorn,
On Tue, Jun 16, 2020 at 6:05 PM Bjorn Helgaas <helgaas@...nel.org> wrote:
>
> On Tue, Jun 16, 2020 at 04:55:16PM -0400, Jim Quinlan wrote:
> > BrcmSTB PCIe controllers are intimately connected to the memory
> > controller(s) on the SOC. There is a "viewport" for each memory controller
> > that allows inbound accesses to CPU memory. Each viewport's size must be
> > set to a power of two, and that size must be equal to or larger than the
> > amount of memory each controller supports.
>
> This describes some requirements, but doesn't actually say what this
> patch *does*.
>
> I *think* it reads the viewport sizes from the "brcm,scb-sizes" DT
> property instead of computing something from "dma-ranges". Looks like
> it also adds support for SCB1 and SCB2.
>
> Those seem interesting, but don't really come through in the subject
> or even the commit log.
>
> If I understand correctly, this is all for DMA ("inbound accesses to
> CPU memory"). I think it would be worth mentioning "DMA", since
> that's the common term for this.
I have changed the commit message to the text below. Please let me
know if it requires more work
Thanks, Jim
PCI: brcmstb: Set internal memory DMA viewport sizes
BrcmSTB PCIe controllers are intimately connected to the memory
controller(s) on the SOC. There is a "viewport" for each memory controller
that allows inbound DMA acceses to CPU memory. Each viewport's size must
be set to a power of two, and that size must be equal to or larger than the
amount of memory each controller supports. Unfortunately the viewport
sizes cannot be ascertained from the "dma-ranges" property so they have
their own property, "brcm,scb-sizes".
There may be one to three memory controllers; they are indicated by the
term SCBi. Each controller has a base region and an optional extension
region. In physical memory, the base and extension regions are not
adjacent, but in PCIe-space they are. Further, the 1-3 viewports are also
adjacent in PCIe-space.
The SCB settings work in conjunction with the "dma-ranges' offsets to
enable non-identity mappings between system memory and PCIe space.
>
>
> > Signed-off-by: Jim Quinlan <james.quinlan@...adcom.com>
> > Acked-by: Florian Fainelli <f.fainelli@...il.com>
> > ---
> > drivers/pci/controller/pcie-brcmstb.c | 68 ++++++++++++++++++++-------
> > 1 file changed, 50 insertions(+), 18 deletions(-)
> >
> > diff --git a/drivers/pci/controller/pcie-brcmstb.c b/drivers/pci/controller/pcie-brcmstb.c
> > index 9189406fd35c..39f77709c6a2 100644
> > --- a/drivers/pci/controller/pcie-brcmstb.c
> > +++ b/drivers/pci/controller/pcie-brcmstb.c
> > @@ -57,6 +57,8 @@
> > #define PCIE_MISC_MISC_CTRL_MAX_BURST_SIZE_MASK 0x300000
> > #define PCIE_MISC_MISC_CTRL_MAX_BURST_SIZE_128 0x0
> > #define PCIE_MISC_MISC_CTRL_SCB0_SIZE_MASK 0xf8000000
> > +#define PCIE_MISC_MISC_CTRL_SCB1_SIZE_MASK 0x07c00000
> > +#define PCIE_MISC_MISC_CTRL_SCB2_SIZE_MASK 0x0000001f
> >
> > #define PCIE_MISC_CPU_2_PCIE_MEM_WIN0_LO 0x400c
> > #define PCIE_MEM_WIN0_LO(win) \
> > @@ -154,6 +156,7 @@
> > #define SSC_STATUS_OFFSET 0x1
> > #define SSC_STATUS_SSC_MASK 0x400
> > #define SSC_STATUS_PLL_LOCK_MASK 0x800
> > +#define PCIE_BRCM_MAX_MEMC 3
> >
> > #define IDX_ADDR(pcie) (pcie->reg_offsets[EXT_CFG_INDEX])
> > #define DATA_ADDR(pcie) (pcie->reg_offsets[EXT_CFG_DATA])
> > @@ -260,6 +263,8 @@ struct brcm_pcie {
> > const int *reg_field_info;
> > enum pcie_type type;
> > struct reset_control *rescal;
> > + int num_memc;
> > + u64 memc_size[PCIE_BRCM_MAX_MEMC];
> > };
> >
> > /*
> > @@ -715,22 +720,44 @@ static inline int brcm_pcie_get_rc_bar2_size_and_offset(struct brcm_pcie *pcie,
> > u64 *rc_bar2_offset)
> > {
> > struct pci_host_bridge *bridge = pci_host_bridge_from_priv(pcie);
> > - struct device *dev = pcie->dev;
> > struct resource_entry *entry;
> > + struct device *dev = pcie->dev;
> > + u64 lowest_pcie_addr = ~(u64)0;
> > + int ret, i = 0;
> > + u64 size = 0;
> >
> > - entry = resource_list_first_type(&bridge->dma_ranges, IORESOURCE_MEM);
> > - if (!entry)
> > - return -ENODEV;
> > + resource_list_for_each_entry(entry, &bridge->dma_ranges) {
> > + u64 pcie_beg = entry->res->start - entry->offset;
> >
> > + size += entry->res->end - entry->res->start + 1;
> > + if (pcie_beg < lowest_pcie_addr)
> > + lowest_pcie_addr = pcie_beg;
> > + }
> >
> > - /*
> > - * The controller expects the inbound window offset to be calculated as
> > - * the difference between PCIe's address space and CPU's. The offset
> > - * provided by the firmware is calculated the opposite way, so we
> > - * negate it.
> > - */
> > - *rc_bar2_offset = -entry->offset;
> > - *rc_bar2_size = 1ULL << fls64(entry->res->end - entry->res->start);
> > + if (lowest_pcie_addr == ~(u64)0) {
> > + dev_err(dev, "DT node has no dma-ranges\n");
> > + return -EINVAL;
> > + }
> > +
> > + ret = of_property_read_variable_u64_array(pcie->np, "brcm,scb-sizes", pcie->memc_size, 1,
> > + PCIE_BRCM_MAX_MEMC);
> > +
> > + if (ret <= 0) {
> > + /* Make an educated guess */
> > + pcie->num_memc = 1;
> > + pcie->memc_size[0] = 1 << fls64(size - 1);
> > + } else {
> > + pcie->num_memc = ret;
> > + }
> > +
> > + /* Each memc is viewed through a "port" that is a power of 2 */
> > + for (i = 0, size = 0; i < pcie->num_memc; i++)
> > + size += pcie->memc_size[i];
> > +
> > + /* System memory starts at this address in PCIe-space */
> > + *rc_bar2_offset = lowest_pcie_addr;
> > + /* The sum of all memc views must also be a power of 2 */
> > + *rc_bar2_size = 1ULL << fls64(size - 1);
> >
> > /*
> > * We validate the inbound memory view even though we should trust
> > @@ -782,12 +809,11 @@ static int brcm_pcie_setup(struct brcm_pcie *pcie)
> > void __iomem *base = pcie->base;
> > struct device *dev = pcie->dev;
> > struct resource_entry *entry;
> > - unsigned int scb_size_val;
> > bool ssc_good = false;
> > struct resource *res;
> > int num_out_wins = 0;
> > u16 nlw, cls, lnksta;
> > - int i, ret;
> > + int i, ret, memc;
> > u32 tmp, aspm_support;
> >
> > /* Reset the bridge */
> > @@ -824,11 +850,17 @@ static int brcm_pcie_setup(struct brcm_pcie *pcie)
> > writel(upper_32_bits(rc_bar2_offset),
> > base + PCIE_MISC_RC_BAR2_CONFIG_HI);
> >
> > - scb_size_val = rc_bar2_size ?
> > - ilog2(rc_bar2_size) - 15 : 0xf; /* 0xf is 1GB */
> > tmp = readl(base + PCIE_MISC_MISC_CTRL);
> > - u32p_replace_bits(&tmp, scb_size_val,
> > - PCIE_MISC_MISC_CTRL_SCB0_SIZE_MASK);
> > + for (memc = 0; memc < pcie->num_memc; memc++) {
> > + u32 scb_size_val = ilog2(pcie->memc_size[memc]) - 15;
> > +
> > + if (memc == 0)
> > + u32p_replace_bits(&tmp, scb_size_val, PCIE_MISC_MISC_CTRL_SCB0_SIZE_MASK);
> > + else if (memc == 1)
> > + u32p_replace_bits(&tmp, scb_size_val, PCIE_MISC_MISC_CTRL_SCB1_SIZE_MASK);
> > + else if (memc == 2)
> > + u32p_replace_bits(&tmp, scb_size_val, PCIE_MISC_MISC_CTRL_SCB2_SIZE_MASK);
> > + }
> > writel(tmp, base + PCIE_MISC_MISC_CTRL);
> >
> > /*
> > --
> > 2.17.1
> >
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