[PATCH v7 11/12] MIPS: CPS: Support broken HCI for multicluster

[Aleksandar Rikalo <arikalo@gmail.com>]

From: Gregory CLEMENT <gregory.clement@bootlin.com>

Some CM3.5 devices incorrectly report that hardware cache
initialization has completed, and also claim to support hardware cache
initialization when they don't actually do so. This commit fixes this
issue by retrieving the correct information from the device tree and
allowing the system to bypass the hardware cache initialization
step. Instead, it relies on manual operation. As a result, multi-user
support is now possible for these CPUs.

Signed-off-by: Gregory CLEMENT <gregory.clement@bootlin.com>
Signed-off-by: Aleksandar Rikalo <arikalo@gmail.com>
---
 arch/mips/kernel/smp-cps.c | 22 +++++++++++++++++++++-
 1 file changed, 21 insertions(+), 1 deletion(-)

diff --git a/arch/mips/kernel/smp-cps.c b/arch/mips/kernel/smp-cps.c
index 4f344c890a23..265cf52c0dd1 100644
--- a/arch/mips/kernel/smp-cps.c
+++ b/arch/mips/kernel/smp-cps.c
@@ -39,6 +39,7 @@ UASM_L_LA(_not_nmi)
 static uint32_t core_entry_reg;
 static phys_addr_t cps_vec_pa;
 
+static bool l2_hci_broken;
 struct cluster_boot_config *mips_cps_cluster_bootcfg;
 
 static void power_up_other_cluster(unsigned int cluster)
@@ -254,6 +255,22 @@ static void __init cps_smp_setup(void)
 #endif /* CONFIG_MIPS_MT_FPAFF */
 }
 
+static void __init check_hci_quirk(void)
+{
+	struct device_node *np;
+
+	np = of_cpu_device_node_get(0);
+	if (!np) {
+		pr_debug("%s: No cpu node in the device tree\n", __func__);
+		return;
+	}
+
+	if (of_property_read_bool(np, "cm3-l2-config-hci-broken")) {
+		pr_info("HCI (Hardware Cache Init for the L2 cache) in GCR_L2_RAM_CONFIG from the CM3 is broken");
+		l2_hci_broken = true;
+	}
+}
+
 static void __init cps_prepare_cpus(unsigned int max_cpus)
 {
 	unsigned int nclusters, ncores, core_vpes, c, cl, cca;
@@ -307,6 +324,9 @@ static void __init cps_prepare_cpus(unsigned int max_cpus)
 					   sizeof(*mips_cps_cluster_bootcfg),
 					   GFP_KERNEL);
 
+	if (nclusters > 1)
+		check_hci_quirk();
+
 	for (cl = 0; cl < nclusters; cl++) {
 		/* Allocate core boot configuration structs */
 		ncores = mips_cps_numcores(cl);
@@ -368,7 +388,7 @@ static void init_cluster_l2(void)
 {
 	u32 l2_cfg, l2sm_cop, result;
 
-	while (1) {
+	while (!l2_hci_broken) {
 		l2_cfg = read_gcr_redir_l2_ram_config();
 
 		/* If HCI is not supported, use the state machine below */
-- 
2.25.1