Hi Arnd
在 2016/9/1 15:41, Arnd Bergmann 写道:
On Thursday, September 1, 2016 10:05:29 AM CEST Dongdong Liu wrote:
在 2016/8/31 19:45, Arnd Bergmann 写道:
On Wednesday, August 31, 2016 7:48:12 PM CEST Dongdong Liu wrote:
+
+/* HipXX PCIe host only supports 32-bit config access */
+int hisi_pcie_common_cfg_read(void __iomem *reg_base, int where, int size,
+ u32 *val)
+{
+ u32 reg;
+ u32 reg_val;
+ void *walker = ®_val;
+
+ walker += (where & 0x3);
+ reg = where & ~0x3;
+ reg_val = readl(reg_base + reg);
+
+ if (size == 1)
+ *val = *(u8 __force *) walker;
+ else if (size == 2)
+ *val = *(u16 __force *) walker;
What is the __force for?
Hi Arnd, thanks for replying.
__force is used to, well, force a conversion, like casting from or to a bitwise type, else the Sparse checker will throw a warning.
I know what it's for in general, but in this case there is no __bitwise
or __iomem or any other annotation on either side of the assignment.
Thanks for you point that.
+ else if (size == 4)
+ *val = reg_val;
+ else
+ return PCIBIOS_BAD_REGISTER_NUMBER;
+
+ return PCIBIOS_SUCCESSFUL;
It looks like you are reimplementing pci_generic_config_read32/pci_generic_config_write32
read here, better use them directly.
For our host bridge, access RC and EP config space are not the same way.
Our host bridge is non ECAM only for the RC bus config space;
for any other bus underneath the root bus we support ECAM access.
hisi_pcie_common_cfg_read is used to read RC config space, only supports 32-bit config access.
hisi_pcie_common_cfg_read/hisi_pcie_common_cfg_write may change as below will be better.
/* HipXX PCIe host only supports 32-bit config access */
int hisi_pcie_common_cfg_read(void __iomem *reg_base, int where, int size,
u32 *val)
{
void __iomem *addr;
addr = reg_base + (where & ~0x3);
*val = readl(addr);
if (size <= 2)
*val = (*val >> (8 * (where & 3))) & ((1 << (size * 8)) - 1);
return PCIBIOS_SUCCESSFUL;
}
My point was: why not call pci_generic_config_read32() when accessing
the RC config space instead of duplicating the code from it?
I know your point.
1. For our host bridge , ".map_bus = pci_ecam_map_bus" is only suitable for
accessing the EP config space.
pci_generic_config_read32() need to call "addr = bus->ops->map_bus(bus, devfn, where & ~0x3);",
drivers/pci/host/pcie-hisi-acpi.c
static struct pci_ops hisi_pcie_ops = {
.map_bus = pci_ecam_map_bus,
.read = hisi_pcie_acpi_rd_conf,
.write = hisi_pcie_acpi_wr_conf,
};
Yes, we can change ".map_bus = pci_ecam_map_bus" to ".map_bus = hisi_pci_map_bus", and implentment hisi_pci_map_bus as below,
then we will not need to call hisi_pcie_common_cfg_read().
void __iomem *hisi_pci_map_bus(struct pci_bus *bus, unsigned int devfn, int where)
{
struct pci_config_window *cfg = bus->sysdata;
void __iomem *reg_base = cfg->priv;
/* for RC config access*/
if (bus->number == cfg->busr.start)
return reg_base + (where & ~0x3);
else
/* for EP config access */
return pci_ecam_map_bus(bus, devfn, where);
}
and hisi_pcie_acpi_rd_conf() need to change as below.
static int hisi_pcie_acpi_rd_conf(struct pci_bus *bus, u32 devfn, int where,
int size, u32 *val)
{
struct pci_config_window *cfg = bus->sysdata;
if (hisi_pcie_acpi_valid_config(cfg, bus, PCI_SLOT(devfn)) == 0)
return PCIBIOS_DEVICE_NOT_FOUND;
/* access RC config space */
if (bus->number == cfg->busr.start)
return pci_generic_config_read32(bus, devfn, where, size, val);
/* access EP config space */
return pci_generic_config_read(bus, devfn, where, size, val);
}
2. We need to backward compatible with the old dt way config access as below code,
so we have to call hisi_pcie_common_cfg_read() when accessing the RC config space.
For this, we have to call hisi_pcie_common_cfg_read().
drivers/pci/host/pcie-hisi.c
static inline int hisi_pcie_cfg_read(struct pcie_port *pp, int where,
int size, u32 *val)
{
struct hisi_pcie *pcie = to_hisi_pcie(pp);
return hisi_pcie_common_cfg_read(pcie->reg_base, where, size, val);
}
static struct pcie_host_ops hisi_pcie_host_ops = {
.rd_own_conf = hisi_pcie_cfg_read,
.wr_own_conf = hisi_pcie_cfg_write,
.link_up = hisi_pcie_link_up,
};
Thanks
Dongdong
Arnd
.
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