drivers: bus: add ARM CCI support

On ARM multi-cluster systems coherency between cores running on
different clusters is managed by the cache-coherent interconnect (CCI).
It allows broadcasting of TLB invalidates and memory barriers and it
guarantees cache coherency at system level through snooping of slave
interfaces connected to it.

This patch enables the basic infrastructure required in Linux to handle and
programme the CCI component.

Non-local variables used by the CCI management functions called by power
down function calls after disabling the cache must be flushed out to main
memory in advance, otherwise incoherency of those values may occur if they
are sitting in the cache of some other CPU when power down functions
execute. Driver code ensures that relevant data structures are flushed
from inner and outer caches after the driver probe is completed.

CCI slave port resources are linked to set of CPUs through bus masters
phandle properties that link the interface resources to masters node in
the device tree.

Documentation describing the CCI DT bindings is provided with the patch.
Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Signed-off-by: Nicolas Pitre <nicolas.pitre@linaro.org>

Documentation/devicetree/bindings/arm/cci.txt

+=======================================================
+ARM CCI cache coherent interconnect binding description
+=======================================================
+
+ARM multi-cluster systems maintain intra-cluster coherency through a
+cache coherent interconnect (CCI) that is capable of monitoring bus
+transactions and manage coherency, TLB invalidations and memory barriers.
+
+It allows snooping and distributed virtual memory message broadcast across
+clusters, through memory mapped interface, with a global control register
+space and multiple sets of interface control registers, one per slave
+interface.
+
+Bindings for the CCI node follow the ePAPR standard, available from:
+
+www.power.org/documentation/epapr-version-1-1/
+
+with the addition of the bindings described in this document which are
+specific to ARM.
+
+* CCI interconnect node
+
+	Description: Describes a CCI cache coherent Interconnect component
+
+	Node name must be "cci".
+	Node's parent must be the root node /, and the address space visible
+	through the CCI interconnect is the same as the one seen from the
+	root node (ie from CPUs perspective as per DT standard).
+	Every CCI node has to define the following properties:
+
+	- compatible
+		Usage: required
+		Value type: <string>
+		Definition: must be set to
+			    "arm,cci-400"
+
+	- reg
+		Usage: required
+		Value type: <prop-encoded-array>
+		Definition: A standard property. Specifies base physical
+			    address of CCI control registers common to all
+			    interfaces.
+
+	- ranges:
+		Usage: required
+		Value type: <prop-encoded-array>
+		Definition: A standard property. Follow rules in the ePAPR for
+			    hierarchical bus addressing. CCI interfaces
+			    addresses refer to the parent node addressing
+			    scheme to declare their register bases.
+
+	CCI interconnect node can define the following child nodes:
+
+	- CCI control interface nodes
+
+		Node name must be "slave-if".
+		Parent node must be CCI interconnect node.
+
+		A CCI control interface node must contain the following
+		properties:
+
+		- compatible
+			Usage: required
+			Value type: <string>
+			Definition: must be set to
+				    "arm,cci-400-ctrl-if"
+
+		- interface-type:
+			Usage: required
+			Value type: <string>
+			Definition: must be set to one of {"ace", "ace-lite"}
+				    depending on the interface type the node
+				    represents.
+
+		- reg:
+			Usage: required
+			Value type: <prop-encoded-array>
+			Definition: the base address and size of the
+				    corresponding interface programming
+				    registers.
+
+* CCI interconnect bus masters
+
+	Description: masters in the device tree connected to a CCI port
+		     (inclusive of CPUs and their cpu nodes).
+
+	A CCI interconnect bus master node must contain the following
+	properties:
+
+	- cci-control-port:
+		Usage: required
+		Value type: <phandle>
+		Definition: a phandle containing the CCI control interface node
+			    the master is connected to.
+
+Example:
+
+	cpus {
+		#size-cells = <0>;
+		#address-cells = <1>;
+
+		CPU0: cpu@0 {
+			device_type = "cpu";
+			compatible = "arm,cortex-a15";
+			cci-control-port = <&cci_control1>;
+			reg = <0x0>;
+		};
+
+		CPU1: cpu@1 {
+			device_type = "cpu";
+			compatible = "arm,cortex-a15";
+			cci-control-port = <&cci_control1>;
+			reg = <0x1>;
+		};
+
+		CPU2: cpu@100 {
+			device_type = "cpu";
+			compatible = "arm,cortex-a7";
+			cci-control-port = <&cci_control2>;
+			reg = <0x100>;
+		};
+
+		CPU3: cpu@101 {
+			device_type = "cpu";
+			compatible = "arm,cortex-a7";
+			cci-control-port = <&cci_control2>;
+			reg = <0x101>;
+		};
+
+	};
+
+	dma0: dma@3000000 {
+		compatible = "arm,pl330", "arm,primecell";
+		cci-control-port = <&cci_control0>;
+		reg = <0x0 0x3000000 0x0 0x1000>;
+		interrupts = <10>;
+		#dma-cells = <1>;
+		#dma-channels = <8>;
+		#dma-requests = <32>;
+	};
+
+	cci@2c090000 {
+		compatible = "arm,cci-400";
+		#address-cells = <1>;
+		#size-cells = <1>;
+		reg = <0x0 0x2c090000 0 0x1000>;
+		ranges = <0x0 0x0 0x2c090000 0x6000>;
+
+		cci_control0: slave-if@1000 {
+			compatible = "arm,cci-400-ctrl-if";
+			interface-type = "ace-lite";
+			reg = <0x1000 0x1000>;
+		};
+
+		cci_control1: slave-if@4000 {
+			compatible = "arm,cci-400-ctrl-if";
+			interface-type = "ace";
+			reg = <0x4000 0x1000>;
+		};
+
+		cci_control2: slave-if@5000 {
+			compatible = "arm,cci-400-ctrl-if";
+			interface-type = "ace";
+			reg = <0x5000 0x1000>;
+		};
+	};
+
+This CCI node corresponds to a CCI component whose control registers sits
+at address 0x000000002c090000.
+CCI slave interface @0x000000002c091000 is connected to dma controller dma0.
+CCI slave interface @0x000000002c094000 is connected to CPUs {CPU0, CPU1};
+CCI slave interface @0x000000002c095000 is connected to CPUs {CPU2, CPU3};

drivers/bus/Kconfig

@@ -26,4 +26,11 @@ config OMAP_INTERCONNECT
 
 	help
 	  Driver to enable OMAP interconnect error handling driver.
+
+config ARM_CCI
+	bool "ARM CCI driver support"
+	depends on ARM
+	help
+	  Driver supporting the CCI cache coherent interconnect for ARM
+	  platforms.
 endmenu

drivers/bus/Makefile

@@ -7,3 +7,5 @@ obj-$(CONFIG_OMAP_OCP2SCP)	+= omap-ocp2scp.o
 
 # Interconnect bus driver for OMAP SoCs.
 obj-$(CONFIG_OMAP_INTERCONNECT)	+= omap_l3_smx.o omap_l3_noc.o
+# CCI cache coherent interconnect for ARM platforms
+obj-$(CONFIG_ARM_CCI)		+= arm-cci.o

include/linux/arm-cci.h

+/*
+ * CCI cache coherent interconnect support
+ *
+ * Copyright (C) 2013 ARM Ltd.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+ */
+
+#ifndef __LINUX_ARM_CCI_H
+#define __LINUX_ARM_CCI_H
+
+#include <linux/errno.h>
+#include <linux/types.h>
+
+struct device_node;
+
+#ifdef CONFIG_ARM_CCI
+extern bool cci_probed(void);
+extern int cci_ace_get_port(struct device_node *dn);
+extern int cci_disable_port_by_cpu(u64 mpidr);
+extern int __cci_control_port_by_device(struct device_node *dn, bool enable);
+extern int __cci_control_port_by_index(u32 port, bool enable);
+#else
+static inline bool cci_probed(void) { return false; }
+static inline int cci_ace_get_port(struct device_node *dn)
+{
+	return -ENODEV;
+}
+static inline int cci_disable_port_by_cpu(u64 mpidr) { return -ENODEV; }
+static inline int __cci_control_port_by_device(struct device_node *dn,
+					       bool enable)
+{
+	return -ENODEV;
+}
+static inline int __cci_control_port_by_index(u32 port, bool enable)
+{
+	return -ENODEV;
+}
+#endif
+#define cci_disable_port_by_device(dev) \
+	__cci_control_port_by_device(dev, false)
+#define cci_enable_port_by_device(dev) \
+	__cci_control_port_by_device(dev, true)
+#define cci_disable_port_by_index(dev) \
+	__cci_control_port_by_index(dev, false)
+#define cci_enable_port_by_index(dev) \
+	__cci_control_port_by_index(dev, true)
+
+#endif