mvebu soc for 4.4 (part 1)

L2 caches optimization for Armada XP
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Merge tag 'mvebu-soc-4.4-1' of git://git.infradead.org/linux-mvebu into next/soc

Merge "mvebu soc for 4.4 (part 1)" from Gregory CLEMENT:

L2 caches optimization for Armada XP

* tag 'mvebu-soc-4.4-1' of git://git.infradead.org/linux-mvebu:
  ARM: mvebu: add support to clear shared L2 bit on Armada XP

Documentation/devicetree/bindings/arm/mvebu-cpu-config.txt

@@ -0,0 +1,20 @@
+MVEBU CPU Config registers
+--------------------------
+
+MVEBU (Marvell SOCs: Armada 370/XP)
+
+Required properties:
+
+- compatible: one of:
+	- "marvell,armada-370-cpu-config"
+	- "marvell,armada-xp-cpu-config"
+
+- reg: Should contain CPU config registers location and length, in
+  their per-CPU variant
+
+Example:
+
+	cpu-config@21000 {
+		compatible = "marvell,armada-xp-cpu-config";
+		reg = <0x21000 0x8>;
+	};

arch/arm/mach-mvebu/coherency.c

@@ -40,6 +40,7 @@
 unsigned long coherency_phys_base;
 void __iomem *coherency_base;
 static void __iomem *coherency_cpu_base;
+static void __iomem *cpu_config_base;
 
 /* Coherency fabric registers */
 #define IO_SYNC_BARRIER_CTL_OFFSET		   0x0
@@ -65,6 +66,31 @@ static const struct of_device_id of_coherency_table[] = {
 int ll_enable_coherency(void);
 void ll_add_cpu_to_smp_group(void);
 
+#define CPU_CONFIG_SHARED_L2 BIT(16)
+
+/*
+ * Disable the "Shared L2 Present" bit in CPU Configuration register
+ * on Armada XP.
+ *
+ * The "Shared L2 Present" bit affects the "level of coherence" value
+ * in the clidr CP15 register.  Cache operation functions such as
+ * "flush all" and "invalidate all" operate on all the cache levels
+ * that included in the defined level of coherence. When HW I/O
+ * coherency is used, this bit causes unnecessary flushes of the L2
+ * cache.
+ */
+static void armada_xp_clear_shared_l2(void)
+{
+	u32 reg;
+
+	if (!cpu_config_base)
+		return;
+
+	reg = readl(cpu_config_base);
+	reg &= ~CPU_CONFIG_SHARED_L2;
+	writel(reg, cpu_config_base);
+}
+
 static int mvebu_hwcc_notifier(struct notifier_block *nb,
 			       unsigned long event, void *__dev)
 {
@@ -85,9 +111,24 @@ static struct notifier_block mvebu_hwcc_pci_nb = {
 	.notifier_call = mvebu_hwcc_notifier,
 };
 
+static int armada_xp_clear_shared_l2_notifier_func(struct notifier_block *nfb,
+					unsigned long action, void *hcpu)
+{
+	if (action == CPU_STARTING || action == CPU_STARTING_FROZEN)
+		armada_xp_clear_shared_l2();
+
+	return NOTIFY_OK;
+}
+
+static struct notifier_block armada_xp_clear_shared_l2_notifier = {
+	.notifier_call = armada_xp_clear_shared_l2_notifier_func,
+	.priority = 100,
+};
+
 static void __init armada_370_coherency_init(struct device_node *np)
 {
 	struct resource res;
+	struct device_node *cpu_config_np;
 
 	of_address_to_resource(np, 0, &res);
 	coherency_phys_base = res.start;
@@ -100,6 +141,23 @@ static void __init armada_370_coherency_init(struct device_node *np)
 	sync_cache_w(&coherency_phys_base);
 	coherency_base = of_iomap(np, 0);
 	coherency_cpu_base = of_iomap(np, 1);
+
+	cpu_config_np = of_find_compatible_node(NULL, NULL,
+						"marvell,armada-xp-cpu-config");
+	if (!cpu_config_np)
+		goto exit;
+
+	cpu_config_base = of_iomap(cpu_config_np, 0);
+	if (!cpu_config_base) {
+		of_node_put(cpu_config_np);
+		goto exit;
+	}
+
+	of_node_put(cpu_config_np);
+
+	register_cpu_notifier(&armada_xp_clear_shared_l2_notifier);
+
+exit:
 	set_cpu_coherent();
 }
 
@@ -204,6 +262,8 @@ int set_cpu_coherent(void)
 			pr_warn("Coherency fabric is not initialized\n");
 			return 1;
 		}
+
+		armada_xp_clear_shared_l2();
 		ll_add_cpu_to_smp_group();
 		return ll_enable_coherency();
 	}