[PATCH 2/8] pci: pci_mvebu: Fix read_config() with PCI_SIZE_8 or PCI_SIZE_16

Pali Rohár
2021-10-22T14:23:15Z

When reading 8 or 16 bits from config space, use appropriate readb() or
readw() calls. This ensures that PCIe controller does not read more bits
from endpoint card as asked by read_config() function.

Technically there should not be an issue with reading data from config
space which are not later used as there are no clear-by-read registers.
But it is better to use correct read operation based on requested size.

Signed-off-by: Pali Rohár <pali@kernel.org>
Reviewed-by: Marek Behún <marek.behun@nic.cz>
---
drivers/pci/pci_mvebu.c | 17 +++++++++++++++--
1 file changed, 15 insertions(+), 2 deletions(-)

diff --git a/drivers/pci/pci_mvebu.c b/drivers/pci/pci_mvebu.c
index 8175511514ab..3991086e0d29 100644
--- a/drivers/pci/pci_mvebu.c
+++ b/drivers/pci/pci_mvebu.c
@@ -184,9 +184,22 @@ static int mvebu_pcie_read_config(const struct udevice *bus, pci_dev_t bdf,
writel(PCIE_CONF_ADDR(bdf, offset), pcie->base + PCIE_CONF_ADDR_OFF);

/* read data */
- data = readl(pcie->base + PCIE_CONF_DATA_OFF);
+ switch (size) {
+ case PCI_SIZE_8:
+ data = readb(pcie->base + PCIE_CONF_DATA_OFF + (offset & 3));
+ break;
+ case PCI_SIZE_16:
+ data = readw(pcie->base + PCIE_CONF_DATA_OFF + (offset & 2));
+ break;
+ case PCI_SIZE_32:
+ data = readl(pcie->base + PCIE_CONF_DATA_OFF);
+ break;
+ default:
+ return -EINVAL;
+ }
+
debug("(addr,size,val)=(0x%04x, %d, 0x%08x)\n", offset, size, data);
- *valuep = pci_conv_32_to_size(data, offset, size);
+ *valuep = data;

return 0;
}
--
2.20.1