bus: NVIDIA Tegra ACONNECT support

Adds support for the Tegra ACONNECT bus that's used to access the APE
 (audio processing engine) on Tegra X1.
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Merge tag 'tegra-for-4.8-bus' of git://git.kernel.org/pub/scm/linux/kernel/git/tegra/linux into next/drivers

bus: NVIDIA Tegra ACONNECT support

Adds support for the Tegra ACONNECT bus that's used to access the APE
(audio processing engine) on Tegra X1.

* tag 'tegra-for-4.8-bus' of git://git.kernel.org/pub/scm/linux/kernel/git/tegra/linux:
  bus: Add support for Tegra ACONNECT
  dt-bindings: bus: Add documentation for Tegra210 ACONNECT

Signed-off-by: Olof Johansson <olof@lixom.net>

Documentation/devicetree/bindings/bus/nvidia,tegra210-aconnect.txt

@@ -0,0 +1,45 @@
+NVIDIA Tegra ACONNECT Bus
+
+The Tegra ACONNECT bus is an AXI switch which is used to connnect various
+components inside the Audio Processing Engine (APE). All CPU accesses to
+the APE subsystem go through the ACONNECT via an APB to AXI wrapper.
+
+Required properties:
+- compatible: Must be "nvidia,tegra210-aconnect".
+- clocks: Must contain the entries for the APE clock (TEGRA210_CLK_APE),
+  and APE interface clock (TEGRA210_CLK_APB2APE).
+- clock-names: Must contain the names "ape" and "apb2ape" for the corresponding
+  'clocks' entries.
+- power-domains: Must contain a phandle that points to the audio powergate
+  (namely 'aud') for Tegra210.
+- #address-cells: The number of cells used to represent physical base addresses
+  in the aconnect address space. Should be 1.
+- #size-cells: The number of cells used to represent the size of an address
+  range in the aconnect address space. Should be 1.
+- ranges: Mapping of the aconnect address space to the CPU address space.
+
+All devices accessed via the ACONNNECT are described by child-nodes.
+
+Example:
+
+	aconnect@702c0000 {
+		compatible = "nvidia,tegra210-aconnect";
+		clocks = <&tegra_car TEGRA210_CLK_APE>,
+			 <&tegra_car TEGRA210_CLK_APB2APE>;
+		clock-names = "ape", "apb2ape";
+		power-domains = <&pd_audio>;
+
+		#address-cells = <1>;
+		#size-cells = <1>;
+		ranges = <0x702c0000 0x0 0x702c0000 0x00040000>;
+
+		status = "disabled";
+
+		child1 {
+			...
+		};
+
+		child2 {
+			...
+		};
+	};

drivers/bus/Kconfig

@@ -132,6 +132,19 @@ config SUNXI_RSB
 	  with various RSB based devices, such as AXP223, AXP8XX PMICs,
 	  and AC100/AC200 ICs.
 
+# TODO: This uses pm_clk_*() symbols that aren't exported in v4.7 and hence
+# the driver will fail to build as a module. However there are patches to
+# address that queued for v4.8, so this can be turned into a tristate symbol
+# after v4.8-rc1.
+config TEGRA_ACONNECT
+	bool "Tegra ACONNECT Bus Driver"
+	depends on ARCH_TEGRA_210_SOC
+	depends on OF && PM
+	select PM_CLK
+	help
+	  Driver for the Tegra ACONNECT bus which is used to interface with
+	  the devices inside the Audio Processing Engine (APE) for Tegra210.
+
 config UNIPHIER_SYSTEM_BUS
 	tristate "UniPhier System Bus driver"
 	depends on ARCH_UNIPHIER && OF

drivers/bus/Makefile

@@ -17,5 +17,6 @@ obj-$(CONFIG_OMAP_INTERCONNECT)	+= omap_l3_smx.o omap_l3_noc.o
 obj-$(CONFIG_OMAP_OCP2SCP)	+= omap-ocp2scp.o
 obj-$(CONFIG_SUNXI_RSB)		+= sunxi-rsb.o
 obj-$(CONFIG_SIMPLE_PM_BUS)	+= simple-pm-bus.o
+obj-$(CONFIG_TEGRA_ACONNECT)	+= tegra-aconnect.o
 obj-$(CONFIG_UNIPHIER_SYSTEM_BUS)	+= uniphier-system-bus.o
 obj-$(CONFIG_VEXPRESS_CONFIG)	+= vexpress-config.o

drivers/bus/tegra-aconnect.c

@@ -0,0 +1,112 @@
+/*
+ * Tegra ACONNECT Bus Driver
+ *
+ * Copyright (C) 2016, NVIDIA CORPORATION.  All rights reserved.
+ *
+ * This file is subject to the terms and conditions of the GNU General Public
+ * License.  See the file "COPYING" in the main directory of this archive
+ * for more details.
+ */
+
+#include <linux/clk.h>
+#include <linux/module.h>
+#include <linux/of_platform.h>
+#include <linux/platform_device.h>
+#include <linux/pm_clock.h>
+#include <linux/pm_runtime.h>
+
+static int tegra_aconnect_add_clock(struct device *dev, char *name)
+{
+	struct clk *clk;
+	int ret;
+
+	clk = clk_get(dev, name);
+	if (IS_ERR(clk)) {
+		dev_err(dev, "%s clock not found\n", name);
+		return PTR_ERR(clk);
+	}
+
+	ret = pm_clk_add_clk(dev, clk);
+	if (ret)
+		clk_put(clk);
+
+	return ret;
+}
+
+static int tegra_aconnect_probe(struct platform_device *pdev)
+{
+	int ret;
+
+	if (!pdev->dev.of_node)
+		return -EINVAL;
+
+	ret = pm_clk_create(&pdev->dev);
+	if (ret)
+		return ret;
+
+	ret = tegra_aconnect_add_clock(&pdev->dev, "ape");
+	if (ret)
+		goto clk_destroy;
+
+	ret = tegra_aconnect_add_clock(&pdev->dev, "apb2ape");
+	if (ret)
+		goto clk_destroy;
+
+	pm_runtime_enable(&pdev->dev);
+
+	of_platform_populate(pdev->dev.of_node, NULL, NULL, &pdev->dev);
+
+	dev_info(&pdev->dev, "Tegra ACONNECT bus registered\n");
+
+	return 0;
+
+clk_destroy:
+	pm_clk_destroy(&pdev->dev);
+
+	return ret;
+}
+
+static int tegra_aconnect_remove(struct platform_device *pdev)
+{
+	pm_runtime_disable(&pdev->dev);
+
+	pm_clk_destroy(&pdev->dev);
+
+	return 0;
+}
+
+static int tegra_aconnect_runtime_resume(struct device *dev)
+{
+	return pm_clk_resume(dev);
+}
+
+static int tegra_aconnect_runtime_suspend(struct device *dev)
+{
+	return pm_clk_suspend(dev);
+}
+
+static const struct dev_pm_ops tegra_aconnect_pm_ops = {
+	SET_RUNTIME_PM_OPS(tegra_aconnect_runtime_suspend,
+			   tegra_aconnect_runtime_resume, NULL)
+};
+
+static const struct of_device_id tegra_aconnect_of_match[] = {
+	{ .compatible = "nvidia,tegra210-aconnect", },
+	{ }
+};
+MODULE_DEVICE_TABLE(of, tegra_aconnect_of_match);
+
+static struct platform_driver tegra_aconnect_driver = {
+	.probe = tegra_aconnect_probe,
+	.remove = tegra_aconnect_remove,
+	.driver = {
+		.name = "tegra-aconnect",
+		.of_match_table = tegra_aconnect_of_match,
+		.pm = &tegra_aconnect_pm_ops,
+	},
+};
+module_platform_driver(tegra_aconnect_driver);
+
+MODULE_DESCRIPTION("NVIDIA Tegra ACONNECT Bus Driver");
+MODULE_AUTHOR("Jon Hunter <jonathanh@nvidia.com>");
+MODULE_LICENSE("GPL v2");