Re: [PATCH v9 1/4] pci:host: APM X-Gene PCIe host controller driver

Bjorn Helgaas
2014-09-19T22:33:08Z

On Tue, Sep 16, 2014 at 03:33:41PM -0700, Tanmay Inamdar wrote:
> This patch adds the AppliedMicro X-Gene SOC PCIe host controller driver.
> X-Gene PCIe controller supports maximum up to 8 lanes and GEN3 speed.
> X-Gene SOC supports maximum 5 PCIe ports.
>
> Reviewed-by: Liviu Dudau <Liviu.Dudau@arm.com>
> Signed-off-by: Tanmay Inamdar <tinamdar@apm.com>
> ---
> drivers/pci/host/Kconfig | 10 +
> drivers/pci/host/Makefile | 1 +
> drivers/pci/host/pci-xgene.c | 646 +++++++++++++++++++++++++++++++++++++++++++
> 3 files changed, 657 insertions(+)
> create mode 100644 drivers/pci/host/pci-xgene.c
> ...

> +static inline void
> +xgene_pcie_cfg_in16(void __iomem *addr, int offset, u32 *val)

Whitespace - can fit on one line. Also others below.

> +{
> + *val = readl(addr + (offset & ~0x3));
> +
> + switch (offset & 0x3) {
> + case 2:
> + *val >>= 16;
> + break;
> + }
> +
> + *val &= 0xFFFF;
> +}
> +
> +static inline void
> +xgene_pcie_cfg_in8(void __iomem *addr, int offset, u32 *val)
> +{
> + *val = readl(addr + (offset & ~0x3));
> +
> + switch (offset & 0x3) {
> + case 3:
> + *val = *val >> 24;
> + break;
> + case 2:
> + *val = *val >> 16;
> + break;
> + case 1:
> + *val = *val >> 8;
> + break;
> + }
> + *val &= 0xFF;
> +}
> +
> +/* When the address bit [17:16] is 2'b01, the Configuration access will be
> + * treated as Type 1 and it will be forwarded to external PCIe device.
> + */

Follow usual block comment style:

/*
* text
*/

> ...
> +static void xgene_pcie_fixup_bridge(struct pci_dev *dev)
> +{
> + int i;
> +
> + /* Hide the PCI host BARs from the kernel as their content doesn't
> + * fit well in the resource management
> + */

This needs a better explanation than "doesn't fit well."

I *think* you're probably talking about something similar to the MVEBU
devices mentioned here:
http://lkml.kernel.org/r/CAErSpo56jB1Bf2JtYCGKXZBZqRF1jXFxGmeewPX_e6vSXueGyA@mail.gmail.com

where the device can be configured as either an endpoint or a root port,
and the endpoint BARs are still visible when configured as a root port.

In any event, I'd like a description of exactly what these BARs are and wha
the problem is. Presumably the BARs exist and were sized by the PCI core
in __pci_read_base(). That will generate some log messages and possibly
some warnings, depending on how the host bridge windows are set up.

We might eventually need a way to skip BARs like that altogether so we
don't even try to size them.

> + for (i = 0; i < DEVICE_COUNT_RESOURCE; i++) {
> + dev->resource[i].start = dev->resource[i].end = 0;
> + dev->resource[i].flags = 0;
> + }
> + dev_info(&dev->dev, "Hiding X-Gene pci host bridge resources %s\n",
> + pci_name(dev));
> +}
> +DECLARE_PCI_FIXUP_HEADER(XGENE_PCIE_VENDORID, XGENE_PCIE_DEVICEID,
> + xgene_pcie_fixup_bridge);
> +
> ...

> +static void xgene_pcie_setup_ob_reg(struct xgene_pcie_port *port,
> + struct resource *res, u32 offset,
> + u64 cpu_addr, u64 pci_addr)
> +{
> + void __iomem *base = port->csr_base + offset;
> + resource_size_t size = resource_size(res);
> + u64 restype = resource_type(res);
> + u64 mask = 0;
> + u32 min_size;
> + u32 flag = EN_REG;
> +
> + if (restype == IORESOURCE_MEM) {
> + min_size = SZ_128M;
> + } else {
> + min_size = 128;
> + flag |= OB_LO_IO;
> + }
> +
> + if (size >= min_size)
> + mask = ~(size - 1) | flag;
> + else
> + dev_warn(port->dev, "res size 0x%llx less than minimum 0x%x\n",
> + (u64)size, min_size);

I'd include a %pR here to help identify the offending resource.

> +static int xgene_pcie_map_ranges(struct xgene_pcie_port *port,
> + struct list_head *res,
> + resource_size_t io_base)
> +{
> + struct pci_host_bridge_window *window;
> + struct device *dev = port->dev;
> + int ret;
> +
> + list_for_each_entry(window, res, list) {
> + struct resource *res = window->res;
> + u64 restype = resource_type(res);
> +
> + dev_dbg(port->dev, "0x%08lx 0x%016llx...0x%016llx\n",
> + res->flags, res->start, res->end);

Use %pR here.

> +
> + switch (restype) {
> + case IORESOURCE_IO:
> + xgene_pcie_setup_ob_reg(port, res, OMR3BARL, io_base,
> + res->start - window->offset);
> + ret = pci_remap_iospace(res, io_base);
> + if (ret < 0)
> + return ret;
> + break;
> + case IORESOURCE_MEM:
> + xgene_pcie_setup_ob_reg(port, res, OMR1BARL, res->start,
> + res->start - window->offset);
> + break;
> + case IORESOURCE_BUS:
> + break;
> + default:
> + dev_err(dev, "invalid io resource!");

If you're going to print something here, you might as well include the type
that seems invalid. If you use %pR, I think it will do that automatically.

> + return -EINVAL;
> + }
> + }
> + xgene_pcie_setup_cfg_reg(port->csr_base, port->cfg_addr);
> +
> + return 0;
> +}

Bjorn