[PATCH RFCv1 1/6] ARM: mvebu: prepare coherency code to support more SOCs

[Thomas Petazzoni]

The code that handles the coherency fabric of Armada 370 and Armada XP
in arch/arm/mach-mvebu/coherency.c made the assumption that there was
only one type of coherency fabric. Unfortunately, it turns out that
upcoming SoCs have a slightly different coherency unit.

In preparation to the introduction of the coherency support for more
SoCs, this commit:

 * Adds a new "marvell,armada-370-coherency-fabric" compatible string,
   to indicate the Armada 370/XP variant of the coherency fabric. The
   existing compatible string "marvel,coherency-fabric" is preserved
   for compatibility reasons, and has the same behavior as
   the new "marvell,armada-370-coherency-fabric".

 * Introduces a data associated to the compatible string in the
   compatible string match table, so that the code can differantiate
   the variant of coherency unit being used.

 * Separates the coherency unit initialization code into its own
   function.

Signed-off-by: Thomas Petazzoni <thomas.petazzoni at free-electrons.com>
---
 .../devicetree/bindings/arm/coherency-fabric.txt   | 12 ++++-
 arch/arm/mach-mvebu/coherency.c                    | 53 ++++++++++++++++------
 2 files changed, 49 insertions(+), 16 deletions(-)

diff --git a/Documentation/devicetree/bindings/arm/coherency-fabric.txt b/Documentation/devicetree/bindings/arm/coherency-fabric.txt
index 17d8cd1..6bd8788 100644
--- a/Documentation/devicetree/bindings/arm/coherency-fabric.txt
+++ b/Documentation/devicetree/bindings/arm/coherency-fabric.txt
@@ -4,7 +4,15 @@ Available on Marvell SOCs: Armada 370 and Armada XP
 
 Required properties:
 
-- compatible: "marvell,coherency-fabric"
+- compatible: the possible values are:
+
+ * "marvell,coherency-fabric", kept for backward compatibility reasons
+   only. To be used for the coherency fabric of the Armada 370 and
+   Armada XP. It is recommended to use
+   "marvell,armada-370-coherency-fabric" instead.
+
+ * "marvell,armada-370-coherency-fabric", for the Armada 370 and
+   Armada XP coherency fabric.
 
 - reg: Should contain coherency fabric registers location and
   length. First pair for the coherency fabric registers, second pair
@@ -13,7 +21,7 @@ Required properties:
 Example:
 
 coherency-fabric at d0020200 {
-	compatible = "marvell,coherency-fabric";
+	compatible = "marvell,armada-370-coherency-fabric";
 	reg = <0xd0020200 0xb0>,
 		<0xd0021810 0x1c>;
 
diff --git a/arch/arm/mach-mvebu/coherency.c b/arch/arm/mach-mvebu/coherency.c
index 58adf2f..a8209ae 100644
--- a/arch/arm/mach-mvebu/coherency.c
+++ b/arch/arm/mach-mvebu/coherency.c
@@ -37,8 +37,20 @@ static void __iomem *coherency_cpu_base;
 
 #define IO_SYNC_BARRIER_CTL_OFFSET		   0x0
 
+enum {
+	COHERENCY_FABRIC_TYPE_ARMADA_370_XP,
+};
+
+/*
+ * The "marvell,coherency-fabric" compatible string is kept for
+ * backward compatibility reasons, and is equivalent to
+ * "marvell,armada-370-coherency-fabric".
+ */
 static struct of_device_id of_coherency_table[] = {
-	{.compatible = "marvell,coherency-fabric"},
+	{.compatible = "marvell,coherency-fabric",
+	 .data = (void *) COHERENCY_FABRIC_TYPE_ARMADA_370_XP },
+	{.compatible = "marvell,armada-370-coherency-fabric",
+	 .data = (void *) COHERENCY_FABRIC_TYPE_ARMADA_370_XP },
 	{ /* end of list */ },
 };
 
@@ -120,26 +132,39 @@ static struct notifier_block mvebu_hwcc_platform_nb = {
 	.notifier_call = mvebu_hwcc_platform_notifier,
 };
 
+static void __init armada_370_coherency_init(struct device_node *np)
+{
+	struct resource res;
+	of_address_to_resource(np, 0, &res);
+	coherency_phys_base = res.start;
+	/*
+	 * Ensure secondary CPUs will see the updated value,
+	 * which they read before they join the coherency
+	 * fabric, and therefore before they are coherent with
+	 * the boot CPU cache.
+	 */
+	sync_cache_w(&coherency_phys_base);
+	coherency_base = of_iomap(np, 0);
+	coherency_cpu_base = of_iomap(np, 1);
+	set_cpu_coherent(cpu_logical_map(smp_processor_id()), 0);
+}
+
 int __init coherency_init(void)
 {
 	struct device_node *np;
 
 	np = of_find_matching_node(NULL, of_coherency_table);
 	if (np) {
-		struct resource res;
+		const struct of_device_id *match =
+			of_match_node(of_coherency_table, np);
+		int type;
+
+		type = (int) match->data;
 		pr_info("Initializing Coherency fabric\n");
-		of_address_to_resource(np, 0, &res);
-		coherency_phys_base = res.start;
-		/*
-		 * Ensure secondary CPUs will see the updated value,
-		 * which they read before they join the coherency
-		 * fabric, and therefore before they are coherent with
-		 * the boot CPU cache.
-		 */
-		sync_cache_w(&coherency_phys_base);
-		coherency_base = of_iomap(np, 0);
-		coherency_cpu_base = of_iomap(np, 1);
-		set_cpu_coherent(cpu_logical_map(smp_processor_id()), 0);
+
+		if (type == COHERENCY_FABRIC_TYPE_ARMADA_370_XP)
+			armada_370_coherency_init(np);
+
 		of_node_put(np);
 	}
 
-- 
1.8.3.2