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PCI: thunder: Don't clobber read-only bits in bridge config registers

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The 32-bit addressing modes in the I/O and Prefetchable Memory registers
are required to be read-only.  Since the underlying access method allows
them to be set, emulate their read-only nature and always set them.

Signed-off-by: David Daney <david.daney@cavium.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
This commit is contained in:
David Daney 2016-04-11 16:29:32 -07:00 committed by Bjorn Helgaas
parent 9735a22799
commit 93bf9073a8
1 changed files with 34 additions and 8 deletions
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42
drivers/pci/host/pci-thunder-pem.c
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@ -153,11 +153,11 @@ static int thunder_pem_config_read(struct pci_bus *bus, unsigned int devfn,
* reserved bits, this makes the code simpler and is OK as the bits
* are not affected by writing zeros to them.
*/
static u32 thunder_pem_bridge_w1c_bits(int where)
static u32 thunder_pem_bridge_w1c_bits(u64 where_aligned)
{
u32 w1c_bits = 0;
switch (where & ~3) {
switch (where_aligned) {
case 0x04: /* Command/Status */
case 0x1c: /* Base and I/O Limit/Secondary Status */
w1c_bits = 0xff000000;
@ -184,12 +184,34 @@ static u32 thunder_pem_bridge_w1c_bits(int where)
return w1c_bits;
}
/* Some bits must be written to one so they appear to be read-only. */
static u32 thunder_pem_bridge_w1_bits(u64 where_aligned)
{
u32 w1_bits;
switch (where_aligned) {
case 0x1c: /* I/O Base / I/O Limit, Secondary Status */
/* Force 32-bit I/O addressing. */
w1_bits = 0x0101;
break;
case 0x24: /* Prefetchable Memory Base / Prefetchable Memory Limit */
/* Force 64-bit addressing */
w1_bits = 0x00010001;
break;
default:
w1_bits = 0;
break;
}
return w1_bits;
}
static int thunder_pem_bridge_write(struct pci_bus *bus, unsigned int devfn,
int where, int size, u32 val)
{
struct gen_pci *pci = bus->sysdata;
struct thunder_pem_pci *pem_pci;
u64 write_val, read_val;
u64 where_aligned = where & ~3ull;
u32 mask = 0;
pem_pci = container_of(pci, struct thunder_pem_pci, gen_pci);
@ -205,8 +227,7 @@ static int thunder_pem_bridge_write(struct pci_bus *bus, unsigned int devfn,
*/
switch (size) {
case 1:
read_val = where & ~3ull;
writeq(read_val, pem_pci->pem_reg_base + PEM_CFG_RD);
writeq(where_aligned, pem_pci->pem_reg_base + PEM_CFG_RD);
read_val = readq(pem_pci->pem_reg_base + PEM_CFG_RD);
read_val >>= 32;
mask = ~(0xff << (8 * (where & 3)));
@ -215,8 +236,7 @@ static int thunder_pem_bridge_write(struct pci_bus *bus, unsigned int devfn,
val |= (u32)read_val;
break;
case 2:
read_val = where & ~3ull;
writeq(read_val, pem_pci->pem_reg_base + PEM_CFG_RD);
writeq(where_aligned, pem_pci->pem_reg_base + PEM_CFG_RD);
read_val = readq(pem_pci->pem_reg_base + PEM_CFG_RD);
read_val >>= 32;
mask = ~(0xffff << (8 * (where & 3)));
@ -243,12 +263,18 @@ static int thunder_pem_bridge_write(struct pci_bus *bus, unsigned int devfn,
}
}
/*
* Some bits must be read-only with value of one. Since the
* access method allows these to be cleared if a zero is
* written, force them to one before writing.
*/
val |= thunder_pem_bridge_w1_bits(where_aligned);
/*
* Low order bits are the config address, the high order 32
* bits are the data to be written.
*/
write_val = where & ~3ull;
write_val |= (((u64)val) << 32);
write_val = (((u64)val) << 32) | where_aligned;
writeq(write_val, pem_pci->pem_reg_base + PEM_CFG_WR);
return PCIBIOS_SUCCESSFUL;
}