The R-Car PCIe host controller does not handle L1 ASPM. Instead, the
hardware needs assistance to transition to L1. When the controller
has received a PM_ENTER_L1 DLLP, we can't access a card's config regs
until we have got it out of L1 link state. The host controller will
handle this as long as it has also been transitioned to L1 link state.
So, when attempting a config access, check to see if the card has gone
into L1, and if so, do the same for the host controller.
This is based on a patch by Hien Dang <hien.dang.eb@xxxxxxxxxxxxxxx>
Signed-off-by: Phil Edworthy <phil.edworthy@xxxxxxxxxxx>
---
drivers/pci/host/pcie-rcar.c | 25 +++++++++++++++++++++++++
1 file changed, 25 insertions(+)
diff --git a/drivers/pci/host/pcie-rcar.c b/drivers/pci/host/pcie-rcar.c
index c72c0ae..4a4f8e1 100644
--- a/drivers/pci/host/pcie-rcar.c
+++ b/drivers/pci/host/pcie-rcar.c
@@ -83,6 +83,14 @@
#define MACSR 0x011054
#define MACCTLR 0x011058
#define SCRAMBLE_DISABLE (1 << 27)
+#define PMSR 0x01105c
+#define L1FAEG (1 << 31)
+#define PM_ENTER_L1RX (1 << 23)
+#define PMSTATE (7 << 16)
+#define PMSTATE_L1 (3 << 16)
+#define PMCTLR 0x011060
+#define L1_INIT (1 << 31)
+
/* R-Car H1 PHY */
#define H1_PCIEPHYADRR 0x04000c
@@ -175,6 +183,7 @@ static int rcar_pcie_config_access(struct rcar_pcie *pcie,
unsigned int devfn, int where, u32 *data)
{
int dev, func, reg, index;
+ u32 val;
dev = PCI_SLOT(devfn);
func = PCI_FUNC(devfn);
@@ -216,6 +225,22 @@ static int rcar_pcie_config_access(struct rcar_pcie *pcie,
if (pcie->root_bus_nr < 0)
return PCIBIOS_DEVICE_NOT_FOUND;
+ /*
+ * If we are not in L1 link state but have received PM_ENTER_L1 DLLP,
+ * transition to L1 link state. The HW will handle coming out of L1.
+ */
+ val = rcar_pci_read_reg(pcie, PMSR);
+ if ((val & PM_ENTER_L1RX) && ((val & PMSTATE) != PMSTATE_L1)) {
+ rcar_pci_write_reg(pcie, L1_INIT, PMCTLR);
+
+ /* Wait until we are in L1 */
+ while (!(val & L1FAEG))
+ val = rcar_pci_read_reg(pcie, PMSR);
+
+ /* Clear flags indicating link has transitioned to L1 */
+ rcar_pci_write_reg(pcie, L1FAEG | PM_ENTER_L1RX, PMSR);
+ }
+
/* Clear errors */
rcar_pci_write_reg(pcie, rcar_pci_read_reg(pcie, PCIEERRFR), PCIEERRFR);
--
2.5.0
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