mowgli: Limit slot1 to Gen3 by default

Refer to the spec. of mowgli, limit the slot to Gen3 speed.
For mowgli platform spec.

Cc: skiboot-stable@lists.ozlabs.org
Signed-off-by: LuluTHSu <Lulu_Su@wistron.com>
Signed-off-by: Oliver O'Halloran <oohall@gmail.com>

1 files changed, 21 insertions, 0 deletions

diff --git a/hw/phb4.c b/hw/phb4.c
index 17a233f..de10bb0 100644
--- a/hw/phb4.c
+++ b/hw/phb4.c
@@ -2991,6 +2991,27 @@ static unsigned int phb4_get_max_link_speed(struct phb4 *p, struct dt_node *np)
 	return max_link_speed;
 }
 
+/*
+ * Has the same effect as the ibm,max-link-speed property.
+ * i.e. sets the default link speed, while allowing NVRAM
+ * overrides, etc to still take effect.
+ */
+void phb4_set_dt_max_link_speed(struct phb4 *p, int new_max)
+{
+	uint64_t scr;
+	int max;
+
+	/* take into account nvram settings, etc */
+	if (pcie_max_link_speed) 
+		max = pcie_max_link_speed;
+	else 
+		max = new_max;
+	
+	scr = phb4_read_reg(p, PHB_PCIE_SCR);
+	scr = SETFIELD(PHB_PCIE_SCR_MAXLINKSPEED, scr, max);
+	phb4_write_reg(p, PHB_PCIE_SCR, scr);
+}
+
 static void phb4_assert_perst(struct pci_slot *slot, bool assert)
 {
 	struct phb4 *p = phb_to_phb4(slot->phb);