arm: mvebu: Add support for coherency fabric in mach-mvebu

The Armada 370 and Armada XP SOCs have a coherency fabric unit which
is responsible for ensuring hardware coherency between all CPUs and
between CPUs and I/O masters. This patch provides the basic support
needed for SMP.

Signed-off-by: Yehuda Yitschak <yehuday@marvell.com>
Signed-off-by: Gregory CLEMENT <gregory.clement@free-electrons.com>
Reviewed-by: Will Deacon <will.deacon@arm.com>

Documentation/devicetree/bindings/arm/coherency-fabric.txt

@@ -0,0 +1,16 @@
+Coherency fabric
+----------------
+Available on Marvell SOCs: Armada 370 and Armada XP
+
+Required properties:
+
+- compatible: "marvell,coherency-fabric"
+- reg: Should contain,coherency fabric registers location and length.
+
+Example:
+
+coherency-fabric@d0020200 {
+	compatible = "marvell,coherency-fabric";
+	reg = <0xd0020200 0xb0>;
+};
+

arch/arm/boot/dts/armada-370-xp.dtsi

@@ -36,6 +36,11 @@ mpic: interrupt-controller@d0020000 {
 	      interrupt-controller;
 	};
 
+	coherency-fabric@d0020200 {
+		compatible = "marvell,coherency-fabric";
+		reg = <0xd0020200 0xb0>;
+	};
+
 	soc {
 		#address-cells = <1>;
 		#size-cells = <1>;

arch/arm/mach-mvebu/Makefile

@@ -2,4 +2,4 @@ ccflags-$(CONFIG_ARCH_MULTIPLATFORM) := -I$(srctree)/$(src)/include \
 	-I$(srctree)/arch/arm/plat-orion/include
 
 obj-y += system-controller.o
-obj-$(CONFIG_MACH_ARMADA_370_XP) += armada-370-xp.o irq-armada-370-xp.o addr-map.o
+obj-$(CONFIG_MACH_ARMADA_370_XP) += armada-370-xp.o irq-armada-370-xp.o addr-map.o coherency.o coherency_ll.o

arch/arm/mach-mvebu/coherency.c

@@ -0,0 +1,82 @@
+/*
+ * Coherency fabric (Aurora) support for Armada 370 and XP platforms.
+ *
+ * Copyright (C) 2012 Marvell
+ *
+ * Yehuda Yitschak <yehuday@marvell.com>
+ * Gregory Clement <gregory.clement@free-electrons.com>
+ * Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
+ *
+ * This file is licensed under the terms of the GNU General Public
+ * License version 2.  This program is licensed "as is" without any
+ * warranty of any kind, whether express or implied.
+ *
+ * The Armada 370 and Armada XP SOCs have a coherency fabric which is
+ * responsible for ensuring hardware coherency between all CPUs and between
+ * CPUs and I/O masters. This file initializes the coherency fabric and
+ * supplies basic routines for configuring and controlling hardware coherency
+ */
+
+#include <linux/kernel.h>
+#include <linux/init.h>
+#include <linux/of_address.h>
+#include <linux/io.h>
+#include <linux/smp.h>
+#include <asm/smp_plat.h>
+#include "armada-370-xp.h"
+
+/*
+ * Some functions in this file are called very early during SMP
+ * initialization. At that time the device tree framework is not yet
+ * ready, and it is not possible to get the register address to
+ * ioremap it. That's why the pointer below is given with an initial
+ * value matching its virtual mapping
+ */
+static void __iomem *coherency_base = ARMADA_370_XP_REGS_VIRT_BASE + 0x20200;
+
+/* Coherency fabric registers */
+#define COHERENCY_FABRIC_CFG_OFFSET		   0x4
+
+static struct of_device_id of_coherency_table[] = {
+	{.compatible = "marvell,coherency-fabric"},
+	{ /* end of list */ },
+};
+
+#ifdef CONFIG_SMP
+int coherency_get_cpu_count(void)
+{
+	int reg, cnt;
+
+	reg = readl(coherency_base + COHERENCY_FABRIC_CFG_OFFSET);
+	cnt = (reg & 0xF) + 1;
+
+	return cnt;
+}
+#endif
+
+/* Function defined in coherency_ll.S */
+int ll_set_cpu_coherent(void __iomem *base_addr, unsigned int hw_cpu_id);
+
+int set_cpu_coherent(unsigned int hw_cpu_id, int smp_group_id)
+{
+	if (!coherency_base) {
+		pr_warn("Can't make CPU %d cache coherent.\n", hw_cpu_id);
+		pr_warn("Coherency fabric is not initialized\n");
+		return 1;
+	}
+
+	return ll_set_cpu_coherent(coherency_base, hw_cpu_id);
+}
+
+int __init coherency_init(void)
+{
+	struct device_node *np;
+
+	np = of_find_matching_node(NULL, of_coherency_table);
+	if (np) {
+		pr_info("Initializing Coherency fabric\n");
+		coherency_base = of_iomap(np, 0);
+	}
+
+	return 0;
+}

arch/arm/mach-mvebu/coherency.h

@@ -0,0 +1,24 @@
+/*
+ * arch/arm/mach-mvebu/include/mach/coherency.h
+ *
+ *
+ * Coherency fabric (Aurora) support for Armada 370 and XP platforms.
+ *
+ * Copyright (C) 2012 Marvell
+ *
+ * This file is licensed under the terms of the GNU General Public
+ * License version 2.  This program is licensed "as is" without any
+ * warranty of any kind, whether express or implied.
+ */
+
+#ifndef __MACH_370_XP_COHERENCY_H
+#define __MACH_370_XP_COHERENCY_H
+
+#ifdef CONFIG_SMP
+int coherency_get_cpu_count(void);
+#endif
+
+int set_cpu_coherent(int cpu_id, int smp_group_id);
+int coherency_init(void);
+
+#endif	/* __MACH_370_XP_COHERENCY_H */

arch/arm/mach-mvebu/coherency_ll.S

@@ -0,0 +1,49 @@
+/*
+ * Coherency fabric: low level functions
+ *
+ * Copyright (C) 2012 Marvell
+ *
+ * Gregory CLEMENT <gregory.clement@free-electrons.com>
+ *
+ * This file is licensed under the terms of the GNU General Public
+ * License version 2.  This program is licensed "as is" without any
+ * warranty of any kind, whether express or implied.
+ *
+ * This file implements the assembly function to add a CPU to the
+ * coherency fabric. This function is called by each of the secondary
+ * CPUs during their early boot in an SMP kernel, this why this
+ * function have to callable from assembly. It can also be called by a
+ * primary CPU from C code during its boot.
+ */
+
+#include <linux/linkage.h>
+#define ARMADA_XP_CFB_CTL_REG_OFFSET 0x0
+#define ARMADA_XP_CFB_CFG_REG_OFFSET 0x4
+
+	.text
+/*
+ * r0: Coherency fabric base register address
+ * r1: HW CPU id
+ */
+ENTRY(ll_set_cpu_coherent)
+	/* Create bit by cpu index */
+	mov	r3, #(1 << 24)
+	lsl	r1, r3, r1
+
+	/* Add CPU to SMP group - Atomic */
+	add	r3, r0, #ARMADA_XP_CFB_CTL_REG_OFFSET
+	ldr	r2, [r3]
+	orr	r2, r2, r1
+	str	r2, [r3]
+
+	/* Enable coherency on CPU - Atomic */
+	add	r3, r0, #ARMADA_XP_CFB_CFG_REG_OFFSET
+	ldr	r2, [r3]
+	orr	r2, r2, r1
+	str	r2, [r3]
+
+	dsb
+
+	mov	r0, #0
+	mov	pc, lr
+ENDPROC(ll_set_cpu_coherent)

arch/arm/mach-mvebu/common.h

@@ -20,4 +20,5 @@ void mvebu_restart(char mode, const char *cmd);
 void armada_370_xp_init_irq(void);
 void armada_370_xp_handle_irq(struct pt_regs *regs);
 
+int armada_370_xp_coherency_init(void);
 #endif