[Skiboot] [PATCH 1/2] mowgli: Limit slot1 to Gen3 by default

[Lulu Su]

From: LuluTHSu <Lulu_Su at wistron.com>

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

Cc: skiboot-stable at lists.ozlabs.org
Signed-off-by: LuluTHSu <Lulu_Su at wistron.com>
---
 hw/phb4.c                 | 21 +++++++++++++++++++++
 include/phb4.h            |  1 +
 platforms/astbmc/mowgli.c | 16 ++++++++++++++++
 3 files changed, 38 insertions(+)

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);
diff --git a/include/phb4.h b/include/phb4.h
index abba2d9..47a46b7 100644
--- a/include/phb4.h
+++ b/include/phb4.h
@@ -259,4 +259,5 @@ static inline int phb4_get_opal_id(unsigned int chip_id, unsigned int index)
 
 void phb4_pec2_dma_engine_realloc(struct phb4 *p);
 
+void phb4_set_dt_max_link_speed(struct phb4 *p, int new_max);
 #endif /* __PHB4_H */
diff --git a/platforms/astbmc/mowgli.c b/platforms/astbmc/mowgli.c
index 9bfe7a4..0246bff 100644
--- a/platforms/astbmc/mowgli.c
+++ b/platforms/astbmc/mowgli.c
@@ -12,6 +12,8 @@
 #include <psi.h>
 #include <npu-regs.h>
 #include <secvar.h>
+#include <pci.h>
+#include <phb4.h>
 
 #include "astbmc.h"
 
@@ -71,6 +73,19 @@ static int mowgli_secvar_init(void)
 	return secvar_main(secboot_tpm_driver, edk2_compatible_v1);
 }
 
+/*
+ * Limit PHB0/(pec0) to gen3 speeds.
+ */
+static void mowgli_setup_phb(struct phb *phb, unsigned int __unused index)
+{
+	struct phb4 *p = phb_to_phb4(phb);
+
+ 	if (p->pec == 0) {
+		phb4_set_dt_max_link_speed(p, 3);
+		prlog(PR_DEBUG, "Mowgli: Force the PHB%d Speed to Gen3.\n", p->pec);
+	} 
+}
+
 DECLARE_PLATFORM(mowgli) = {
 	.name			= "Mowgli",
 	.probe			= mowgli_probe,
@@ -80,6 +95,7 @@ DECLARE_PLATFORM(mowgli) = {
 	.bmc			= &bmc_plat_ast2500_openbmc,
 	.pci_get_slot_info	= slot_table_get_slot_info,
 	.pci_probe_complete	= check_all_slot_table,
+	.pci_setup_phb 		= mowgli_setup_phb,
 	.cec_power_down         = astbmc_ipmi_power_down,
 	.cec_reboot             = astbmc_ipmi_reboot,
 	.elog_commit		= ipmi_elog_commit,
-- 
2.7.4