MIPS: cm: Detect CM quirks from device tree

Some information that should be retrieved at runtime for the Coherence
Manager can be either absent or wrong. This patch allows checking if
some of this information is available from the device tree and updates
the internal variable accordingly.

For now, only the compatible string associated with the broken HCI is
being retrieved.

Signed-off-by: Gregory CLEMENT <gregory.clement@bootlin.com>
Signed-off-by: Thomas Bogendoerfer <tsbogend@alpha.franken.de>

arch/mips/include/asm/mips-cm.h

@@ -59,6 +59,16 @@ extern phys_addr_t mips_cm_l2sync_phys_base(void);
  */
 extern int mips_cm_is64;
 
+/*
+ * mips_cm_is_l2_hci_broken  - determine if HCI is broken
+ *
+ * Some CM reports show that Hardware Cache Initialization is
+ * complete, but in reality it's not the case. They also incorrectly
+ * indicate that Hardware Cache Initialization is supported. This
+ * flags allows warning about this broken feature.
+ */
+extern bool mips_cm_is_l2_hci_broken;
+
 /**
  * mips_cm_error_report - Report CM cache errors
  */
@@ -97,6 +107,18 @@ static inline bool mips_cm_present(void)
 #endif
 }
 
+/**
+ * mips_cm_update_property - update property from the device tree
+ *
+ * Retrieve the properties from the device tree if a CM node exist and
+ * update the internal variable based on this.
+ */
+#ifdef CONFIG_MIPS_CM
+extern void mips_cm_update_property(void);
+#else
+static void mips_cm_update_property(void) {}
+#endif
+
 /**
  * mips_cm_has_l2sync - determine whether an L2-only sync region is present
  *

arch/mips/kernel/mips-cm.c

@@ -5,6 +5,7 @@
  */
 
 #include <linux/errno.h>
+#include <linux/of.h>
 #include <linux/percpu.h>
 #include <linux/spinlock.h>
 
@@ -14,6 +15,7 @@
 void __iomem *mips_gcr_base;
 void __iomem *mips_cm_l2sync_base;
 int mips_cm_is64;
+bool mips_cm_is_l2_hci_broken;
 
 static char *cm2_tr[8] = {
 	"mem",	"gcr",	"gic",	"mmio",
@@ -237,6 +239,18 @@ static void mips_cm_probe_l2sync(void)
 	mips_cm_l2sync_base = ioremap(addr, MIPS_CM_L2SYNC_SIZE);
 }
 
+void mips_cm_update_property(void)
+{
+	struct device_node *cm_node;
+
+	cm_node = of_find_compatible_node(of_root, NULL, "mobileye,eyeq6-cm");
+	if (!cm_node)
+		return;
+	pr_info("HCI (Hardware Cache Init for the L2 cache) in GCR_L2_RAM_CONFIG from the CM3 is broken");
+	mips_cm_is_l2_hci_broken = true;
+	of_node_put(cm_node);
+}
+
 int mips_cm_probe(void)
 {
 	phys_addr_t addr;