Merge tag 'arm-scpi-for-v4.4' of git://git.kernel.org/pub/scm/linux/kernel/git/sudeep.holla/linux into next/drivers

Merge "ARM System Control and Power Interface(SCPI) support" from Sudeep Holla

It adds support for the following features provided by SCP firmware
using different subsystems in Linux:
  1. SCPI mailbox protocol driver which using mailbox framework
  2. Clocks provided by SCP using clock framework
  3. CPU DVFS(cpufreq) using existing arm-big-little driver
  4. SCPI based sensors including temperature sensors

* tag 'arm-scpi-for-v4.4' of git://git.kernel.org/pub/scm/linux/kernel/git/sudeep.holla/linux:
  hwmon: Support thermal zones registration for SCP temperature sensors
  hwmon: Support sensors exported via ARM SCP interface
  firmware: arm_scpi: Extend to support sensors
  Documentation: add DT bindings for ARM SCPI sensors
  cpufreq: arm_big_little: add SCPI interface driver
  clk: scpi: add support for cpufreq virtual device
  clk: add support for clocks provided by SCP(System Control Processor)
  firmware: add support for ARM System Control and Power Interface(SCPI) protocol
  Documentation: add DT binding for ARM System Control and Power Interface(SCPI) protocol

16 files changed, 1868 insertions, 0 deletions

diff --git a/Documentation/devicetree/bindings/arm/arm,scpi.txt b/Documentation/devicetree/bindings/arm/arm,scpi.txt
new file mode 100644
index 000000000000..86302de67c2c
--- /dev/null
+++ b/Documentation/devicetree/bindings/arm/arm,scpi.txt
@@ -0,0 +1,188 @@
+System Control and Power Interface (SCPI) Message Protocol
+----------------------------------------------------------
+
+Firmware implementing the SCPI described in ARM document number ARM DUI 0922B
+("ARM Compute Subsystem SCP: Message Interface Protocols")[0] can be used
+by Linux to initiate various system control and power operations.
+
+Required properties:
+
+- compatible : should be "arm,scpi"
+- mboxes: List of phandle and mailbox channel specifiers
+	  All the channels reserved by remote SCP firmware for use by
+	  SCPI message protocol should be specified in any order
+- shmem : List of phandle pointing to the shared memory(SHM) area between the
+	  processors using these mailboxes for IPC, one for each mailbox
+	  SHM can be any memory reserved for the purpose of this communication
+	  between the processors.
+
+See Documentation/devicetree/bindings/mailbox/mailbox.txt
+for more details about the generic mailbox controller and
+client driver bindings.
+
+Clock bindings for the clocks based on SCPI Message Protocol
+------------------------------------------------------------
+
+This binding uses the common clock binding[1].
+
+Container Node
+==============
+Required properties:
+- compatible : should be "arm,scpi-clocks"
+	       All the clocks provided by SCP firmware via SCPI message
+	       protocol much be listed as sub-nodes under this node.
+
+Sub-nodes
+=========
+Required properties:
+- compatible : shall include one of the following
+	"arm,scpi-dvfs-clocks" - all the clocks that are variable and index based.
+		These clocks don't provide an entire range of values between the
+		limits but only discrete points within the range. The firmware
+		provides the mapping for each such operating frequency and the
+		index associated with it. The firmware also manages the
+		voltage scaling appropriately with the clock scaling.
+	"arm,scpi-variable-clocks" - all the clocks that are variable and provide full
+		range within the specified range. The firmware provides the
+		range of values within a specified range.
+
+Other required properties for all clocks(all from common clock binding):
+- #clock-cells : Should be 1. Contains the Clock ID value used by SCPI commands.
+- clock-output-names : shall be the corresponding names of the outputs.
+- clock-indices: The identifying number for the clocks(i.e.clock_id) in the
+	node. It can be non linear and hence provide the mapping of identifiers
+	into the clock-output-names array.
+
+SRAM and Shared Memory for SCPI
+-------------------------------
+
+A small area of SRAM is reserved for SCPI communication between application
+processors and SCP.
+
+Required properties:
+- compatible : should be "arm,juno-sram-ns" for Non-secure SRAM on Juno
+
+The rest of the properties should follow the generic mmio-sram description
+found in ../../misc/sysram.txt
+
+Each sub-node represents the reserved area for SCPI.
+
+Required sub-node properties:
+- reg : The base offset and size of the reserved area with the SRAM
+- compatible : should be "arm,juno-scp-shmem" for Non-secure SRAM based
+	       shared memory on Juno platforms
+
+Sensor bindings for the sensors based on SCPI Message Protocol
+--------------------------------------------------------------
+SCPI provides an API to access the various sensors on the SoC.
+
+Required properties:
+- compatible : should be "arm,scpi-sensors".
+- #thermal-sensor-cells: should be set to 1. This property follows the
+			 thermal device tree bindings[2].
+
+			 Valid cell values are raw identifiers (Sensor
+			 ID) as used by the firmware. Refer to
+			 platform documentation for your
+			 implementation for the IDs to use. For Juno
+			 R0 and Juno R1 refer to [3].
+
+[0] http://infocenter.arm.com/help/topic/com.arm.doc.dui0922b/index.html
+[1] Documentation/devicetree/bindings/clock/clock-bindings.txt
+[2] Documentation/devicetree/bindings/thermal/thermal.txt
+[3] http://infocenter.arm.com/help/index.jsp?topic=/com.arm.doc.dui0922b/apas03s22.html
+
+Example:
+
+sram: sram@50000000 {
+	compatible = "arm,juno-sram-ns", "mmio-sram";
+	reg = <0x0 0x50000000 0x0 0x10000>;
+
+	#address-cells = <1>;
+	#size-cells = <1>;
+	ranges = <0 0x0 0x50000000 0x10000>;
+
+	cpu_scp_lpri: scp-shmem@0 {
+		compatible = "arm,juno-scp-shmem";
+		reg = <0x0 0x200>;
+	};
+
+	cpu_scp_hpri: scp-shmem@200 {
+		compatible = "arm,juno-scp-shmem";
+		reg = <0x200 0x200>;
+	};
+};
+
+mailbox: mailbox0@40000000 {
+	....
+	#mbox-cells = <1>;
+};
+
+scpi_protocol: scpi@2e000000 {
+	compatible = "arm,scpi";
+	mboxes = <&mailbox 0 &mailbox 1>;
+	shmem = <&cpu_scp_lpri &cpu_scp_hpri>;
+
+	clocks {
+		compatible = "arm,scpi-clocks";
+
+		scpi_dvfs: scpi_clocks@0 {
+			compatible = "arm,scpi-dvfs-clocks";
+			#clock-cells = <1>;
+			clock-indices = <0>, <1>, <2>;
+			clock-output-names = "atlclk", "aplclk","gpuclk";
+		};
+		scpi_clk: scpi_clocks@3 {
+			compatible = "arm,scpi-variable-clocks";
+			#clock-cells = <1>;
+			clock-indices = <3>, <4>;
+			clock-output-names = "pxlclk0", "pxlclk1";
+		};
+	};
+
+	scpi_sensors0: sensors {
+		compatible = "arm,scpi-sensors";
+		#thermal-sensor-cells = <1>;
+	};
+};
+
+cpu@0 {
+	...
+	reg = <0 0>;
+	clocks = <&scpi_dvfs 0>;
+};
+
+hdlcd@7ff60000 {
+	...
+	reg = <0 0x7ff60000 0 0x1000>;
+	clocks = <&scpi_clk 4>;
+};
+
+thermal-zones {
+	soc_thermal {
+		polling-delay-passive = <100>;
+		polling-delay = <1000>;
+
+				/* sensor         ID */
+		thermal-sensors = <&scpi_sensors0 3>;
+		...
+	};
+};
+
+In the above example, the #clock-cells is set to 1 as required.
+scpi_dvfs has 3 output clocks namely: atlclk, aplclk, and gpuclk with 0,
+1 and 2 as clock-indices. scpi_clk has 2 output clocks namely: pxlclk0
+and pxlclk1 with 3 and 4 as clock-indices.
+
+The first consumer in the example is cpu@0 and it has '0' as the clock
+specifier which points to the first entry in the output clocks of
+scpi_dvfs i.e. "atlclk".
+
+Similarly the second example is hdlcd@7ff60000 and it has pxlclk1 as input
+clock. '4' in the clock specifier here points to the second entry
+in the output clocks of scpi_clocks  i.e. "pxlclk1"
+
+The thermal-sensors property in the soc_thermal node uses the
+temperature sensor provided by SCP firmware to setup a thermal
+zone. The ID "3" is the sensor identifier for the temperature sensor
+as used by the firmware.
diff --git a/Documentation/hwmon/scpi-hwmon b/Documentation/hwmon/scpi-hwmon
new file mode 100644
index 000000000000..4cfcdf2d5eab
--- /dev/null
+++ b/Documentation/hwmon/scpi-hwmon
@@ -0,0 +1,33 @@
+Kernel driver scpi-hwmon
+========================
+
+Supported chips:
+ * Chips based on ARM System Control Processor Interface
+   Addresses scanned: -
+   Datasheet: http://infocenter.arm.com/help/index.jsp?topic=/com.arm.doc.dui0922b/index.html
+
+Author: Punit Agrawal <punit.agrawal@arm.com>
+
+Description
+-----------
+
+This driver supports hardware monitoring for SoC's based on the ARM
+System Control Processor (SCP) implementing the System Control
+Processor Interface (SCPI). The following sensor types are supported
+by the SCP -
+
+  * temperature
+  * voltage
+  * current
+  * power
+
+The SCP interface provides an API to query the available sensors and
+their values which are then exported to userspace by this driver.
+
+Usage Notes
+-----------
+
+The driver relies on device tree node to indicate the presence of SCPI
+support in the kernel. See
+Documentation/devicetree/bindings/arm/arm,scpi.txt for details of the
+devicetree node.
\ No newline at end of file
diff --git a/MAINTAINERS b/MAINTAINERS
index 797236befd27..960d31031e4b 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -9153,6 +9153,16 @@ W:	http://www.sunplus.com
 S:	Supported
 F:	arch/score/
 
+SYSTEM CONTROL & POWER INTERFACE (SCPI) Message Protocol drivers
+M:	Sudeep Holla <sudeep.holla@arm.com>
+L:	linux-arm-kernel@lists.infradead.org
+S:	Maintained
+F:	Documentation/devicetree/bindings/arm/arm,scpi.txt
+F:	drivers/clk/clk-scpi.c
+F:	drivers/cpufreq/scpi-cpufreq.c
+F:	drivers/firmware/arm_scpi.c
+F:	include/linux/scpi_protocol.h
+
 SCSI CDROM DRIVER
 M:	Jens Axboe <axboe@kernel.dk>
 L:	linux-scsi@vger.kernel.org
diff --git a/drivers/clk/Kconfig b/drivers/clk/Kconfig
index 42f7120ca9ce..4aec54b90331 100644
--- a/drivers/clk/Kconfig
+++ b/drivers/clk/Kconfig
@@ -59,6 +59,16 @@ config COMMON_CLK_RK808
 	  clocked at 32KHz each. Clkout1 is always on, Clkout2 can off
 	  by control register.
 
+config COMMON_CLK_SCPI
+	tristate "Clock driver controlled via SCPI interface"
+	depends on ARM_SCPI_PROTOCOL || COMPILE_TEST
+	  ---help---
+	  This driver provides support for clocks that are controlled
+	  by firmware that implements the SCPI interface.
+
+	  This driver uses SCPI Message Protocol to interact with the
+	  firmware providing all the clock controls.
+
 config COMMON_CLK_SI5351
 	tristate "Clock driver for SiLabs 5351A/B/C"
 	depends on I2C
diff --git a/drivers/clk/Makefile b/drivers/clk/Makefile
index d08b3e5985be..a381431bd950 100644
--- a/drivers/clk/Makefile
+++ b/drivers/clk/Makefile
@@ -36,6 +36,7 @@ obj-$(CONFIG_COMMON_CLK_PALMAS)		+= clk-palmas.o
 obj-$(CONFIG_CLK_QORIQ)			+= clk-qoriq.o
 obj-$(CONFIG_COMMON_CLK_RK808)		+= clk-rk808.o
 obj-$(CONFIG_COMMON_CLK_S2MPS11)	+= clk-s2mps11.o
+obj-$(CONFIG_COMMON_CLK_SCPI)           += clk-scpi.o
 obj-$(CONFIG_COMMON_CLK_SI5351)		+= clk-si5351.o
 obj-$(CONFIG_COMMON_CLK_SI570)		+= clk-si570.o
 obj-$(CONFIG_COMMON_CLK_CDCE925)	+= clk-cdce925.o
diff --git a/drivers/clk/clk-scpi.c b/drivers/clk/clk-scpi.c
new file mode 100644
index 000000000000..0b501a9fef92
--- /dev/null
+++ b/drivers/clk/clk-scpi.c
@@ -0,0 +1,325 @@
+/*
+ * System Control and Power Interface (SCPI) Protocol based clock driver
+ *
+ * Copyright (C) 2015 ARM Ltd.
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms and conditions of the GNU General Public License,
+ * version 2, as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope 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, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <linux/clk-provider.h>
+#include <linux/device.h>
+#include <linux/err.h>
+#include <linux/of.h>
+#include <linux/module.h>
+#include <linux/of_platform.h>
+#include <linux/platform_device.h>
+#include <linux/scpi_protocol.h>
+
+struct scpi_clk {
+	u32 id;
+	struct clk_hw hw;
+	struct scpi_dvfs_info *info;
+	struct scpi_ops *scpi_ops;
+};
+
+#define to_scpi_clk(clk) container_of(clk, struct scpi_clk, hw)
+
+static struct platform_device *cpufreq_dev;
+
+static unsigned long scpi_clk_recalc_rate(struct clk_hw *hw,
+					  unsigned long parent_rate)
+{
+	struct scpi_clk *clk = to_scpi_clk(hw);
+
+	return clk->scpi_ops->clk_get_val(clk->id);
+}
+
+static long scpi_clk_round_rate(struct clk_hw *hw, unsigned long rate,
+				unsigned long *parent_rate)
+{
+	/*
+	 * We can't figure out what rate it will be, so just return the
+	 * rate back to the caller. scpi_clk_recalc_rate() will be called
+	 * after the rate is set and we'll know what rate the clock is
+	 * running at then.
+	 */
+	return rate;
+}
+
+static int scpi_clk_set_rate(struct clk_hw *hw, unsigned long rate,
+			     unsigned long parent_rate)
+{
+	struct scpi_clk *clk = to_scpi_clk(hw);
+
+	return clk->scpi_ops->clk_set_val(clk->id, rate);
+}
+
+static const struct clk_ops scpi_clk_ops = {
+	.recalc_rate = scpi_clk_recalc_rate,
+	.round_rate = scpi_clk_round_rate,
+	.set_rate = scpi_clk_set_rate,
+};
+
+/* find closest match to given frequency in OPP table */
+static int __scpi_dvfs_round_rate(struct scpi_clk *clk, unsigned long rate)
+{
+	int idx;
+	u32 fmin = 0, fmax = ~0, ftmp;
+	const struct scpi_opp *opp = clk->info->opps;
+
+	for (idx = 0; idx < clk->info->count; idx++, opp++) {
+		ftmp = opp->freq;
+		if (ftmp >= (u32)rate) {
+			if (ftmp <= fmax)
+				fmax = ftmp;
+			break;
+		} else if (ftmp >= fmin) {
+			fmin = ftmp;
+		}
+	}
+	return fmax != ~0 ? fmax : fmin;
+}
+
+static unsigned long scpi_dvfs_recalc_rate(struct clk_hw *hw,
+					   unsigned long parent_rate)
+{
+	struct scpi_clk *clk = to_scpi_clk(hw);
+	int idx = clk->scpi_ops->dvfs_get_idx(clk->id);
+	const struct scpi_opp *opp;
+
+	if (idx < 0)
+		return 0;
+
+	opp = clk->info->opps + idx;
+	return opp->freq;
+}
+
+static long scpi_dvfs_round_rate(struct clk_hw *hw, unsigned long rate,
+				 unsigned long *parent_rate)
+{
+	struct scpi_clk *clk = to_scpi_clk(hw);
+
+	return __scpi_dvfs_round_rate(clk, rate);
+}
+
+static int __scpi_find_dvfs_index(struct scpi_clk *clk, unsigned long rate)
+{
+	int idx, max_opp = clk->info->count;
+	const struct scpi_opp *opp = clk->info->opps;
+
+	for (idx = 0; idx < max_opp; idx++, opp++)
+		if (opp->freq == rate)
+			return idx;
+	return -EINVAL;
+}
+
+static int scpi_dvfs_set_rate(struct clk_hw *hw, unsigned long rate,
+			      unsigned long parent_rate)
+{
+	struct scpi_clk *clk = to_scpi_clk(hw);
+	int ret = __scpi_find_dvfs_index(clk, rate);
+
+	if (ret < 0)
+		return ret;
+	return clk->scpi_ops->dvfs_set_idx(clk->id, (u8)ret);
+}
+
+static const struct clk_ops scpi_dvfs_ops = {
+	.recalc_rate = scpi_dvfs_recalc_rate,
+	.round_rate = scpi_dvfs_round_rate,
+	.set_rate = scpi_dvfs_set_rate,
+};
+
+static const struct of_device_id scpi_clk_match[] = {
+	{ .compatible = "arm,scpi-dvfs-clocks", .data = &scpi_dvfs_ops, },
+	{ .compatible = "arm,scpi-variable-clocks", .data = &scpi_clk_ops, },
+	{}
+};
+
+static struct clk *
+scpi_clk_ops_init(struct device *dev, const struct of_device_id *match,
+		  struct scpi_clk *sclk, const char *name)
+{
+	struct clk_init_data init;
+	struct clk *clk;
+	unsigned long min = 0, max = 0;
+
+	init.name = name;
+	init.flags = CLK_IS_ROOT;
+	init.num_parents = 0;
+	init.ops = match->data;
+	sclk->hw.init = &init;
+	sclk->scpi_ops = get_scpi_ops();
+
+	if (init.ops == &scpi_dvfs_ops) {
+		sclk->info = sclk->scpi_ops->dvfs_get_info(sclk->id);
+		if (IS_ERR(sclk->info))
+			return NULL;
+	} else if (init.ops == &scpi_clk_ops) {
+		if (sclk->scpi_ops->clk_get_range(sclk->id, &min, &max) || !max)
+			return NULL;
+	} else {
+		return NULL;
+	}
+
+	clk = devm_clk_register(dev, &sclk->hw);
+	if (!IS_ERR(clk) && max)
+		clk_hw_set_rate_range(&sclk->hw, min, max);
+	return clk;
+}
+
+struct scpi_clk_data {
+	struct scpi_clk **clk;
+	unsigned int clk_num;
+};
+
+static struct clk *
+scpi_of_clk_src_get(struct of_phandle_args *clkspec, void *data)
+{
+	struct scpi_clk *sclk;
+	struct scpi_clk_data *clk_data = data;
+	unsigned int idx = clkspec->args[0], count;
+
+	for (count = 0; count < clk_data->clk_num; count++) {
+		sclk = clk_data->clk[count];
+		if (idx == sclk->id)
+			return sclk->hw.clk;
+	}
+
+	return ERR_PTR(-EINVAL);
+}
+
+static int scpi_clk_add(struct device *dev, struct device_node *np,
+			const struct of_device_id *match)
+{
+	struct clk **clks;
+	int idx, count;
+	struct scpi_clk_data *clk_data;
+
+	count = of_property_count_strings(np, "clock-output-names");
+	if (count < 0) {
+		dev_err(dev, "%s: invalid clock output count\n", np->name);
+		return -EINVAL;
+	}
+
+	clk_data = devm_kmalloc(dev, sizeof(*clk_data), GFP_KERNEL);
+	if (!clk_data)
+		return -ENOMEM;
+
+	clk_data->clk_num = count;
+	clk_data->clk = devm_kcalloc(dev, count, sizeof(*clk_data->clk),
+				     GFP_KERNEL);
+	if (!clk_data->clk)
+		return -ENOMEM;
+
+	clks = devm_kcalloc(dev, count, sizeof(*clks), GFP_KERNEL);
+	if (!clks)
+		return -ENOMEM;
+
+	for (idx = 0; idx < count; idx++) {
+		struct scpi_clk *sclk;
+		const char *name;
+		u32 val;
+
+		sclk = devm_kzalloc(dev, sizeof(*sclk), GFP_KERNEL);
+		if (!sclk)
+			return -ENOMEM;
+
+		if (of_property_read_string_index(np, "clock-output-names",
+						  idx, &name)) {
+			dev_err(dev, "invalid clock name @ %s\n", np->name);
+			return -EINVAL;
+		}
+
+		if (of_property_read_u32_index(np, "clock-indices",
+					       idx, &val)) {
+			dev_err(dev, "invalid clock index @ %s\n", np->name);
+			return -EINVAL;
+		}
+
+		sclk->id = val;
+
+		clks[idx] = scpi_clk_ops_init(dev, match, sclk, name);
+		if (IS_ERR_OR_NULL(clks[idx]))
+			dev_err(dev, "failed to register clock '%s'\n", name);
+		else
+			dev_dbg(dev, "Registered clock '%s'\n", name);
+		clk_data->clk[idx] = sclk;
+	}
+
+	return of_clk_add_provider(np, scpi_of_clk_src_get, clk_data);
+}
+
+static int scpi_clocks_remove(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct device_node *child, *np = dev->of_node;
+
+	if (cpufreq_dev) {
+		platform_device_unregister(cpufreq_dev);
+		cpufreq_dev = NULL;
+	}
+
+	for_each_available_child_of_node(np, child)
+		of_clk_del_provider(np);
+	return 0;
+}
+
+static int scpi_clocks_probe(struct platform_device *pdev)
+{
+	int ret;
+	struct device *dev = &pdev->dev;
+	struct device_node *child, *np = dev->of_node;
+	const struct of_device_id *match;
+
+	if (!get_scpi_ops())
+		return -ENXIO;
+
+	for_each_available_child_of_node(np, child) {
+		match = of_match_node(scpi_clk_match, child);
+		if (!match)
+			continue;
+		ret = scpi_clk_add(dev, child, match);
+		if (ret) {
+			scpi_clocks_remove(pdev);
+			return ret;
+		}
+	}
+	/* Add the virtual cpufreq device */
+	cpufreq_dev = platform_device_register_simple("scpi-cpufreq",
+						      -1, NULL, 0);
+	if (!cpufreq_dev)
+		pr_warn("unable to register cpufreq device");
+
+	return 0;
+}
+
+static const struct of_device_id scpi_clocks_ids[] = {
+	{ .compatible = "arm,scpi-clocks", },
+	{}
+};
+MODULE_DEVICE_TABLE(of, scpi_clocks_ids);
+
+static struct platform_driver scpi_clocks_driver = {
+	.driver	= {
+		.name = "scpi_clocks",
+		.of_match_table = scpi_clocks_ids,
+	},
+	.probe = scpi_clocks_probe,
+	.remove = scpi_clocks_remove,
+};
+module_platform_driver(scpi_clocks_driver);
+
+MODULE_AUTHOR("Sudeep Holla <sudeep.holla@arm.com>");
+MODULE_DESCRIPTION("ARM SCPI clock driver");
+MODULE_LICENSE("GPL v2");
diff --git a/drivers/cpufreq/Kconfig.arm b/drivers/cpufreq/Kconfig.arm
index cd0391e46c6d..c737f7359974 100644
--- a/drivers/cpufreq/Kconfig.arm
+++ b/drivers/cpufreq/Kconfig.arm
@@ -199,6 +199,16 @@ config ARM_SA1100_CPUFREQ
 config ARM_SA1110_CPUFREQ
 	bool
 
+config ARM_SCPI_CPUFREQ
+        tristate "SCPI based CPUfreq driver"
+	depends on ARM_BIG_LITTLE_CPUFREQ && ARM_SCPI_PROTOCOL
+        help
+	  This adds the CPUfreq driver support for ARM big.LITTLE platforms
+	  using SCPI protocol for CPU power management.
+
+	  This driver uses SCPI Message Protocol driver to interact with the
+	  firmware providing the CPU DVFS functionality.
+
 config ARM_SPEAR_CPUFREQ
 	bool "SPEAr CPUFreq support"
 	depends on PLAT_SPEAR
diff --git a/drivers/cpufreq/Makefile b/drivers/cpufreq/Makefile
index 41340384f11f..ccfaa4c68a9a 100644
--- a/drivers/cpufreq/Makefile
+++ b/drivers/cpufreq/Makefile
@@ -72,6 +72,7 @@ obj-$(CONFIG_ARM_S3C64XX_CPUFREQ)	+= s3c64xx-cpufreq.o
 obj-$(CONFIG_ARM_S5PV210_CPUFREQ)	+= s5pv210-cpufreq.o
 obj-$(CONFIG_ARM_SA1100_CPUFREQ)	+= sa1100-cpufreq.o
 obj-$(CONFIG_ARM_SA1110_CPUFREQ)	+= sa1110-cpufreq.o
+obj-$(CONFIG_ARM_SCPI_CPUFREQ)		+= scpi-cpufreq.o
 obj-$(CONFIG_ARM_SPEAR_CPUFREQ)		+= spear-cpufreq.o
 obj-$(CONFIG_ARM_TEGRA20_CPUFREQ)	+= tegra20-cpufreq.o
 obj-$(CONFIG_ARM_TEGRA124_CPUFREQ)	+= tegra124-cpufreq.o
diff --git a/drivers/cpufreq/scpi-cpufreq.c b/drivers/cpufreq/scpi-cpufreq.c
new file mode 100644
index 000000000000..2c3b16fd3a01
--- /dev/null
+++ b/drivers/cpufreq/scpi-cpufreq.c
@@ -0,0 +1,124 @@
+/*
+ * System Control and Power Interface (SCPI) based CPUFreq Interface driver
+ *
+ * It provides necessary ops to arm_big_little cpufreq driver.
+ *
+ * Copyright (C) 2015 ARM Ltd.
+ * Sudeep Holla <sudeep.holla@arm.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ * This program is distributed "as is" WITHOUT ANY WARRANTY of any
+ * kind, whether express or implied; without even the implied warranty
+ * of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/cpufreq.h>
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/pm_opp.h>
+#include <linux/scpi_protocol.h>
+#include <linux/types.h>
+
+#include "arm_big_little.h"
+
+static struct scpi_ops *scpi_ops;
+
+static struct scpi_dvfs_info *scpi_get_dvfs_info(struct device *cpu_dev)
+{
+	u8 domain = topology_physical_package_id(cpu_dev->id);
+
+	if (domain < 0)
+		return ERR_PTR(-EINVAL);
+	return scpi_ops->dvfs_get_info(domain);
+}
+
+static int scpi_opp_table_ops(struct device *cpu_dev, bool remove)
+{
+	int idx, ret = 0;
+	struct scpi_opp *opp;
+	struct scpi_dvfs_info *info = scpi_get_dvfs_info(cpu_dev);
+
+	if (IS_ERR(info))
+		return PTR_ERR(info);
+
+	if (!info->opps)
+		return -EIO;
+
+	for (opp = info->opps, idx = 0; idx < info->count; idx++, opp++) {
+		if (remove)
+			dev_pm_opp_remove(cpu_dev, opp->freq);
+		else
+			ret = dev_pm_opp_add(cpu_dev, opp->freq,
+					     opp->m_volt * 1000);
+		if (ret) {
+			dev_warn(cpu_dev, "failed to add opp %uHz %umV\n",
+				 opp->freq, opp->m_volt);
+			while (idx-- > 0)
+				dev_pm_opp_remove(cpu_dev, (--opp)->freq);
+			return ret;
+		}
+	}
+	return ret;
+}
+
+static int scpi_get_transition_latency(struct device *cpu_dev)
+{
+	struct scpi_dvfs_info *info = scpi_get_dvfs_info(cpu_dev);
+
+	if (IS_ERR(info))
+		return PTR_ERR(info);
+	return info->latency;
+}
+
+static int scpi_init_opp_table(struct device *cpu_dev)
+{
+	return scpi_opp_table_ops(cpu_dev, false);
+}
+
+static void scpi_free_opp_table(struct device *cpu_dev)
+{
+	scpi_opp_table_ops(cpu_dev, true);
+}
+
+static struct cpufreq_arm_bL_ops scpi_cpufreq_ops = {
+	.name	= "scpi",
+	.get_transition_latency = scpi_get_transition_latency,
+	.init_opp_table = scpi_init_opp_table,
+	.free_opp_table = scpi_free_opp_table,
+};
+
+static int scpi_cpufreq_probe(struct platform_device *pdev)
+{
+	scpi_ops = get_scpi_ops();
+	if (!scpi_ops)
+		return -EIO;
+
+	return bL_cpufreq_register(&scpi_cpufreq_ops);
+}
+
+static int scpi_cpufreq_remove(struct platform_device *pdev)
+{
+	bL_cpufreq_unregister(&scpi_cpufreq_ops);
+	scpi_ops = NULL;
+	return 0;
+}
+
+static struct platform_driver scpi_cpufreq_platdrv = {
+	.driver = {
+		.name	= "scpi-cpufreq",
+		.owner	= THIS_MODULE,
+	},
+	.probe		= scpi_cpufreq_probe,
+	.remove		= scpi_cpufreq_remove,
+};
+module_platform_driver(scpi_cpufreq_platdrv);
+
+MODULE_AUTHOR("Sudeep Holla <sudeep.holla@arm.com>");
+MODULE_DESCRIPTION("ARM SCPI CPUFreq interface driver");
+MODULE_LICENSE("GPL v2");
diff --git a/drivers/firmware/Kconfig b/drivers/firmware/Kconfig
index 665efca59487..d00c6d338cc3 100644
--- a/drivers/firmware/Kconfig
+++ b/drivers/firmware/Kconfig
@@ -8,6 +8,25 @@ menu "Firmware Drivers"
 config ARM_PSCI_FW
 	bool
 
+config ARM_SCPI_PROTOCOL
+	tristate "ARM System Control and Power Interface (SCPI) Message Protocol"
+	depends on ARM_MHU
+	help
+	  System Control and Power Interface (SCPI) Message Protocol is
+	  defined for the purpose of communication between the Application
+	  Cores(AP) and the System Control Processor(SCP). The MHU peripheral
+	  provides a mechanism for inter-processor communication between SCP
+	  and AP.
+
+	  SCP controls most of the power managament on the Application
+	  Processors. It offers control and management of: the core/cluster
+	  power states, various power domain DVFS including the core/cluster,
+	  certain system clocks configuration, thermal sensors and many
+	  others.
+
+	  This protocol library provides interface for all the client drivers
+	  making use of the features offered by the SCP.
+
 config EDD
 	tristate "BIOS Enhanced Disk Drive calls determine boot disk"
 	depends on X86
diff --git a/drivers/firmware/Makefile b/drivers/firmware/Makefile
index 2ee83474a3c1..b8a521741418 100644
--- a/drivers/firmware/Makefile
+++ b/drivers/firmware/Makefile
@@ -2,6 +2,7 @@
 # Makefile for the linux kernel.
 #
 obj-$(CONFIG_ARM_PSCI_FW)	+= psci.o
+obj-$(CONFIG_ARM_SCPI_PROTOCOL)	+= arm_scpi.o
 obj-$(CONFIG_DMI)		+= dmi_scan.o
 obj-$(CONFIG_DMI_SYSFS)		+= dmi-sysfs.o
 obj-$(CONFIG_EDD)		+= edd.o
diff --git a/drivers/firmware/arm_scpi.c b/drivers/firmware/arm_scpi.c
new file mode 100644
index 000000000000..6174db80c663
--- /dev/null
+++ b/drivers/firmware/arm_scpi.c
@@ -0,0 +1,771 @@
+/*
+ * System Control and Power Interface (SCPI) Message Protocol driver
+ *
+ * SCPI Message Protocol is used between the System Control Processor(SCP)
+ * and the Application Processors(AP). The Message Handling Unit(MHU)
+ * provides a mechanism for inter-processor communication between SCP's
+ * Cortex M3 and AP.
+ *
+ * SCP offers control and management of the core/cluster power states,
+ * various power domain DVFS including the core/cluster, certain system
+ * clocks configuration, thermal sensors and many others.
+ *
+ * Copyright (C) 2015 ARM Ltd.
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms and conditions of the GNU General Public License,
+ * version 2, as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope 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, see <http://www.gnu.org/licenses/>.
+ */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/bitmap.h>
+#include <linux/device.h>
+#include <linux/err.h>
+#include <linux/export.h>
+#include <linux/io.h>
+#include <linux/kernel.h>
+#include <linux/list.h>
+#include <linux/mailbox_client.h>
+#include <linux/module.h>
+#include <linux/of_address.h>
+#include <linux/of_platform.h>
+#include <linux/printk.h>
+#include <linux/scpi_protocol.h>
+#include <linux/slab.h>
+#include <linux/sort.h>
+#include <linux/spinlock.h>
+
+#define CMD_ID_SHIFT		0
+#define CMD_ID_MASK		0x7f
+#define CMD_TOKEN_ID_SHIFT	8
+#define CMD_TOKEN_ID_MASK	0xff
+#define CMD_DATA_SIZE_SHIFT	16
+#define CMD_DATA_SIZE_MASK	0x1ff
+#define PACK_SCPI_CMD(cmd_id, tx_sz)			\
+	((((cmd_id) & CMD_ID_MASK) << CMD_ID_SHIFT) |	\
+	(((tx_sz) & CMD_DATA_SIZE_MASK) << CMD_DATA_SIZE_SHIFT))
+#define ADD_SCPI_TOKEN(cmd, token)			\
+	((cmd) |= (((token) & CMD_TOKEN_ID_MASK) << CMD_TOKEN_ID_SHIFT))
+
+#define CMD_SIZE(cmd)	(((cmd) >> CMD_DATA_SIZE_SHIFT) & CMD_DATA_SIZE_MASK)
+#define CMD_UNIQ_MASK	(CMD_TOKEN_ID_MASK << CMD_TOKEN_ID_SHIFT | CMD_ID_MASK)
+#define CMD_XTRACT_UNIQ(cmd)	((cmd) & CMD_UNIQ_MASK)
+
+#define SCPI_SLOT		0
+
+#define MAX_DVFS_DOMAINS	8
+#define MAX_DVFS_OPPS		8
+#define DVFS_LATENCY(hdr)	(le32_to_cpu(hdr) >> 16)
+#define DVFS_OPP_COUNT(hdr)	((le32_to_cpu(hdr) >> 8) & 0xff)
+
+#define PROTOCOL_REV_MINOR_BITS	16
+#define PROTOCOL_REV_MINOR_MASK	((1U << PROTOCOL_REV_MINOR_BITS) - 1)
+#define PROTOCOL_REV_MAJOR(x)	((x) >> PROTOCOL_REV_MINOR_BITS)
+#define PROTOCOL_REV_MINOR(x)	((x) & PROTOCOL_REV_MINOR_MASK)
+
+#define FW_REV_MAJOR_BITS	24
+#define FW_REV_MINOR_BITS	16
+#define FW_REV_PATCH_MASK	((1U << FW_REV_MINOR_BITS) - 1)
+#define FW_REV_MINOR_MASK	((1U << FW_REV_MAJOR_BITS) - 1)
+#define FW_REV_MAJOR(x)		((x) >> FW_REV_MAJOR_BITS)
+#define FW_REV_MINOR(x)		(((x) & FW_REV_MINOR_MASK) >> FW_REV_MINOR_BITS)
+#define FW_REV_PATCH(x)		((x) & FW_REV_PATCH_MASK)
+
+#define MAX_RX_TIMEOUT		(msecs_to_jiffies(20))
+
+enum scpi_error_codes {
+	SCPI_SUCCESS = 0, /* Success */
+	SCPI_ERR_PARAM = 1, /* Invalid parameter(s) */
+	SCPI_ERR_ALIGN = 2, /* Invalid alignment */
+	SCPI_ERR_SIZE = 3, /* Invalid size */
+	SCPI_ERR_HANDLER = 4, /* Invalid handler/callback */
+	SCPI_ERR_ACCESS = 5, /* Invalid access/permission denied */
+	SCPI_ERR_RANGE = 6, /* Value out of range */
+	SCPI_ERR_TIMEOUT = 7, /* Timeout has occurred */
+	SCPI_ERR_NOMEM = 8, /* Invalid memory area or pointer */
+	SCPI_ERR_PWRSTATE = 9, /* Invalid power state */
+	SCPI_ERR_SUPPORT = 10, /* Not supported or disabled */
+	SCPI_ERR_DEVICE = 11, /* Device error */
+	SCPI_ERR_B