[PATCH] Revert "ARM: cns3xxx: pci: avoid potential stack overflow"

Bjorn Helgaas
2016-05-31T21:58:07Z

This reverts commit 498a92d42596a7a32c042319eb62a4c3d8081cf1.

Krzysztof reported that this change broke Cavium CNS3xxx, ARMv6 (Laguna
GW-2388) because the MRRS setting is never written to the hardware.

Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
CC: Arnd Bergmann <arnd@arndb.de>
CC: Krzysztof Hałasa <khalasa@piap.pl>
---
arch/arm/mach-cns3xxx/pcie.c | 71 ++++++++++++++++++++++++------------------
1 file changed, 41 insertions(+), 30 deletions(-)

diff --git a/arch/arm/mach-cns3xxx/pcie.c b/arch/arm/mach-cns3xxx/pcie.c
index 318394e..c622c30 100644
--- a/arch/arm/mach-cns3xxx/pcie.c
+++ b/arch/arm/mach-cns3xxx/pcie.c
@@ -65,9 +65,8 @@ static void __iomem *cns3xxx_pci_map_bus(struct pci_bus *bus,

/*
* The CNS PCI bridge doesn't fit into the PCI hierarchy, though
- * we still want to access it.
- * We place the host bridge on bus 0, and the directly connected
- * device on bus 1, slot 0.
+ * we still want to access it. For this to work, we must place
+ * the first device on the same bus as the CNS PCI bridge.
*/
if (busno == 0) { /* internal PCIe bus, host bridge device */
if (devfn == 0) /* device# and function# are ignored by hw */
@@ -212,46 +211,58 @@ static void __init cns3xxx_pcie_check_link(struct cns3xxx_pcie *cnspci)
}
}

-static void cns3xxx_write_config(struct cns3xxx_pcie *cnspci,
- int where, int size, u32 val)
-{
- void __iomem *base = cnspci->host_regs + (where & 0xffc);
- u32 v;
- u32 mask = (0x1ull << (size * 8)) - 1;
- int shift = (where % 4) * 8;
-
- v = readl_relaxed(base);
-
- v &= ~(mask << shift);
- v |= (val & mask) << shift;
-
- writel_relaxed(v, base);
- readl_relaxed(base);
-}
-
static void __init cns3xxx_pcie_hw_init(struct cns3xxx_pcie *cnspci)
{
+ int port = cnspci->port;
+ struct pci_sys_data sd = {
+ .private_data = cnspci,
+ };
+ struct pci_bus bus = {
+ .number = 0,
+ .ops = &cns3xxx_pcie_ops,
+ .sysdata = &sd,
+ };
u16 mem_base = cnspci->res_mem.start >> 16;
u16 mem_limit = cnspci->res_mem.end >> 16;
u16 io_base = cnspci->res_io.start >> 16;
u16 io_limit = cnspci->res_io.end >> 16;
+ u32 devfn = 0;
+ u8 tmp8;
+ u16 pos;
+ u16 dc;
+
+ pci_bus_write_config_byte(&bus, devfn, PCI_PRIMARY_BUS, 0);
+ pci_bus_write_config_byte(&bus, devfn, PCI_SECONDARY_BUS, 1);
+ pci_bus_write_config_byte(&bus, devfn, PCI_SUBORDINATE_BUS, 1);

- cns3xxx_write_config(cnspci, PCI_PRIMARY_BUS, 1, 0);
- cns3xxx_write_config(cnspci, PCI_SECONDARY_BUS, 1, 1);
- cns3xxx_write_config(cnspci, PCI_SUBORDINATE_BUS, 1, 1);
- cns3xxx_write_config(cnspci, PCI_MEMORY_BASE, 2, mem_base);
- cns3xxx_write_config(cnspci, PCI_MEMORY_LIMIT, 2, mem_limit);
- cns3xxx_write_config(cnspci, PCI_IO_BASE_UPPER16, 2, io_base);
- cns3xxx_write_config(cnspci, PCI_IO_LIMIT_UPPER16, 2, io_limit);
+ pci_bus_read_config_byte(&bus, devfn, PCI_PRIMARY_BUS, &tmp8);
+ pci_bus_read_config_byte(&bus, devfn, PCI_SECONDARY_BUS, &tmp8);
+ pci_bus_read_config_byte(&bus, devfn, PCI_SUBORDINATE_BUS, &tmp8);
+
+ pci_bus_write_config_word(&bus, devfn, PCI_MEMORY_BASE, mem_base);
+ pci_bus_write_config_word(&bus, devfn, PCI_MEMORY_LIMIT, mem_limit);
+ pci_bus_write_config_word(&bus, devfn, PCI_IO_BASE_UPPER16, io_base);
+ pci_bus_write_config_word(&bus, devfn, PCI_IO_LIMIT_UPPER16, io_limit);

if (!cnspci->linked)
return;

/* Set Device Max_Read_Request_Size to 128 byte */
- pcie_bus_config = PCIE_BUS_PEER2PEER;
-
+ bus.number = 1; /* directly connected PCIe device */
+ devfn = PCI_DEVFN(0, 0);
+ pos = pci_bus_find_capability(&bus, devfn, PCI_CAP_ID_EXP);
+ pci_bus_read_config_word(&bus, devfn, pos + PCI_EXP_DEVCTL, &dc);
+ if (dc & PCI_EXP_DEVCTL_READRQ) {
+ dc &= ~PCI_EXP_DEVCTL_READRQ;
+ pci_bus_write_config_word(&bus, devfn, pos + PCI_EXP_DEVCTL, dc);
+ pci_bus_read_config_word(&bus, devfn, pos + PCI_EXP_DEVCTL, &dc);
+ if (dc & PCI_EXP_DEVCTL_READRQ)
+ pr_warn("PCIe: Unable to set device Max_Read_Request_Size\n");
+ else
+ pr_info("PCIe: Max_Read_Request_Size set to 128 bytes\n");
+ }
/* Disable PCIe0 Interrupt Mask INTA to INTD */
- __raw_writel(~0x3FFF, MISC_PCIE_INT_MASK(cnspci->port));
+ __raw_writel(~0x3FFF, MISC_PCIE_INT_MASK(port));
}

static int cns3xxx_pcie_abort_handler(unsigned long addr, unsigned int fsr,