On Fri, Oct 13, 2017 at 12:20:06AM +0530, Vidya Sagar wrote:
> use only 4K space from available 1GB PCIe aperture to access
> end points configuration space by dynamically moving AFI_AXI_BAR
> base address and always making sure that the desired location
> to be accessed for generating required config space access falls
> in the 4K space reserved for this purpose. This would give more
> space for mapping end point device's BARs on some of Tegra platforms
Do you now have a revlock issue between this driver change and the
corresponding DT changes? I.e., what happens when you run this driver
change with an older DT that specifies a 256MB config aperture? What
happens if you run the older driver with a new DT that only specifies
a 4KB config aperture?
> Signed-off-by: Vidya Sagar <vidyas@xxxxxxxxxx>
> ---
> drivers/pci/host/pci-tegra.c | 85 ++++++++++++--------------------------------
> 1 file changed, 23 insertions(+), 62 deletions(-)
>
> diff --git a/drivers/pci/host/pci-tegra.c b/drivers/pci/host/pci-tegra.c
> index 9c40da54f88a..ebdcfca10e17 100644
> --- a/drivers/pci/host/pci-tegra.c
> +++ b/drivers/pci/host/pci-tegra.c
> @@ -269,6 +269,8 @@ struct tegra_pcie {
> struct list_head buses;
> struct resource *cs;
>
> + void __iomem *cfg_va_base;
> +
> struct resource io;
> struct resource pio;
> struct resource mem;
> @@ -317,7 +319,6 @@ struct tegra_pcie_port {
> };
>
> struct tegra_pcie_bus {
> - struct vm_struct *area;
> struct list_head list;
> unsigned int nr;
> };
> @@ -357,34 +358,16 @@ static inline u32 pads_readl(struct tegra_pcie *pcie, unsigned long offset)
> *
> * Mapping the whole extended configuration space would require 256 MiB of
> * virtual address space, only a small part of which will actually be used.
> - * To work around this, a 1 MiB of virtual addresses are allocated per bus
> - * when the bus is first accessed. When the physical range is mapped, the
> - * the bus number bits are hidden so that the extended register number bits
> - * appear as bits [19:16]. Therefore the virtual mapping looks like this:
> - *
> - * [19:16] extended register number
> - * [15:11] device number
> - * [10: 8] function number
> - * [ 7: 0] register number
> - *
> - * This is achieved by stitching together 16 chunks of 64 KiB of physical
> - * address space via the MMU.
> + * To work around this, a 4K of region is used to generate required
> + * configuration transaction with relevant B:D:F values. This is achieved by
> + * dynamically programming base address and size of AFI_AXI_BAR used for
> + * end point config space mapping to make sure that the address (access to
> + * which generates correct config transaction) falls in this 4K region
> */
> -static unsigned long tegra_pcie_conf_offset(unsigned int devfn, int where)
> -{
> - return ((where & 0xf00) << 8) | (PCI_SLOT(devfn) << 11) |
> - (PCI_FUNC(devfn) << 8) | (where & 0xfc);
> -}
> -
> static struct tegra_pcie_bus *tegra_pcie_bus_alloc(struct tegra_pcie *pcie,
> unsigned int busnr)
> {
> - struct device *dev = pcie->dev;
> - pgprot_t prot = pgprot_noncached(PAGE_KERNEL);
> - phys_addr_t cs = pcie->cs->start;
> struct tegra_pcie_bus *bus;
> - unsigned int i;
> - int err;
>
> bus = kzalloc(sizeof(*bus), GFP_KERNEL);
> if (!bus)
> @@ -393,33 +376,16 @@ static struct tegra_pcie_bus *tegra_pcie_bus_alloc(struct tegra_pcie *pcie,
> INIT_LIST_HEAD(&bus->list);
> bus->nr = busnr;
>
> - /* allocate 1 MiB of virtual addresses */
> - bus->area = get_vm_area(SZ_1M, VM_IOREMAP);
> - if (!bus->area) {
> - err = -ENOMEM;
> - goto free;
> - }
> -
> - /* map each of the 16 chunks of 64 KiB each */
> - for (i = 0; i < 16; i++) {
> - unsigned long virt = (unsigned long)bus->area->addr +
> - i * SZ_64K;
> - phys_addr_t phys = cs + i * SZ_16M + busnr * SZ_64K;
> -
> - err = ioremap_page_range(virt, virt + SZ_64K, phys, prot);
> - if (err < 0) {
> - dev_err(dev, "ioremap_page_range() failed: %d\n", err);
> - goto unmap;
> + if (!pcie->cfg_va_base) {
> + pcie->cfg_va_base = ioremap(pcie->cs->start, SZ_4K);
> + if (!pcie->cfg_va_base) {
> + dev_err(pcie->dev, "failed to ioremap config space\n");
> + kfree(bus);
> + bus = (struct tegra_pcie_bus *)-ENOMEM;
tegra_pcie_bus_alloc() used to do some bus-specific work -- it allocated VM
space and mapped it. This pcie->cfg_va_base ioremap() is not bus-specific,
so I don't think it fits here. It looks like something that should be done
in the tegra_pcie_probe() path instead.
If you move that, then I think you might as well inline the kzalloc() stuff
into tegra_pcie_add_bus().
> }
> }
>
> return bus;
> -
> -unmap:
> - vunmap(bus->area->addr);
> -free:
> - kfree(bus);
> - return ERR_PTR(err);
> }
>
> static int tegra_pcie_add_bus(struct pci_bus *bus)
> @@ -445,12 +411,12 @@ static void tegra_pcie_remove_bus(struct pci_bus *child)
>
> list_for_each_entry_safe(bus, tmp, &pcie->buses, list) {
> if (bus->nr == child->number) {
> - vunmap(bus->area->addr);
> list_del(&bus->list);
> kfree(bus);
> break;
> }
> }
> + iounmap(pcie->cfg_va_base);
> }
>
> static void __iomem *tegra_pcie_map_bus(struct pci_bus *bus,
> @@ -459,8 +425,8 @@ static void __iomem *tegra_pcie_map_bus(struct pci_bus *bus,
> {
> struct pci_host_bridge *host = pci_find_host_bridge(bus);
> struct tegra_pcie *pcie = pci_host_bridge_priv(host);
> - struct device *dev = pcie->dev;
> void __iomem *addr = NULL;
> + u32 val = 0;
>
> if (bus->number == 0) {
> unsigned int slot = PCI_SLOT(devfn);
> @@ -473,19 +439,14 @@ static void __iomem *tegra_pcie_map_bus(struct pci_bus *bus,
> }
> }
> } else {
> - struct tegra_pcie_bus *b;
> -
> - list_for_each_entry(b, &pcie->buses, list)
> - if (b->nr == bus->number)
> - addr = (void __iomem *)b->area->addr;
> -
> - if (!addr) {
> - dev_err(dev, "failed to map cfg. space for bus %u\n",
> - bus->number);
> - return NULL;
> - }
> -
> - addr += tegra_pcie_conf_offset(devfn, where);
> + addr = pcie->cfg_va_base;
> + val = ((((u32)where & 0xf00) >> 8) << 24) |
> + (bus->number << 16) | (PCI_SLOT(devfn) << 11) |
> + (PCI_FUNC(devfn) << 8) | (where & 0xff);
I think it would be useful to keep tegra_pcie_conf_offset() (extending
it to take the bus number) near the comment describing the mapping.
> + addr = (val & (SZ_4K - 1)) + addr;
> + val = val & ~(SZ_4K - 1);
val &= ~(SZ_4K - 1);
I *think* what you're doing is computing a config space offset and
mapping the 4KB window that contains it.
"addr" is not used at all in the AFI_AXI_BAR0 programming, so this
would be clearer as:
val = ...
afi_writel(...)
afi_writel(...)
addr = pcie->cfg_va_base + (val & (SZ_4K - 1));
}
return addr;
> + afi_writel(pcie, pcie->cs->start - val, AFI_AXI_BAR0_START);
> + afi_writel(pcie, (val + SZ_4K) >> 12, AFI_AXI_BAR0_SZ);
> }
>
> return addr;
> --
> 2.7.4
>
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