ACPI/ARM: Add AMBA bus ACPI module

This AMBA bus ACPI module provides a generic handler for compatible
devices.

It uses the same common code as the device tree method to probe for a hardware
ID and match up a driver for each device.

Signed-off-by: Brandon Anderson <brandon.anderson@amd.com>
Reviewed-by: Naresh Bhat <naresh.bhat@linaro.org>

3 files changed, 367 insertions, 1 deletions

diff --git a/drivers/amba/Makefile b/drivers/amba/Makefile
index 66e81c2f1e3c..6d088e7ed24b 100644
--- a/drivers/amba/Makefile
+++ b/drivers/amba/Makefile
@@ -1,2 +1,2 @@
-obj-$(CONFIG_ARM_AMBA)		+= bus.o
+obj-$(CONFIG_ARM_AMBA)		+= bus.o acpi.o
 obj-$(CONFIG_TEGRA_AHB)		+= tegra-ahb.o
diff --git a/drivers/amba/acpi.c b/drivers/amba/acpi.c
new file mode 100644
index 000000000000..9a97cd8ad433
--- /dev/null
+++ b/drivers/amba/acpi.c
@@ -0,0 +1,337 @@
+/*
+ * AMBA Connector Resource for ACPI
+ *
+ * Copyright (C) 2013 Advanced Micro Devices, Inc.
+ *
+ * Author: Brandon Anderson <brandon.anderson@amd.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.
+ */
+
+#ifdef CONFIG_ACPI
+
+#include <linux/module.h>
+#include <linux/amba/bus.h>
+#include <linux/platform_device.h>
+#include <linux/acpi.h>
+#include <linux/clkdev.h>
+#include <linux/amba/acpi.h>
+
+struct acpi_amba_bus_info {
+	struct platform_device *pdev;
+	struct clk *clk;
+	char *clk_name;
+};
+
+/* UUID: a706b112-bf0b-48d2-9fa3-95591a3c4c06 (randomly generated) */
+static const char acpi_amba_dsm_uuid[] = {
+	0xa7, 0x06, 0xb1, 0x12, 0xbf, 0x0b, 0x48, 0xd2,
+	0x9f, 0xa3, 0x95, 0x59, 0x1a, 0x3c, 0x4c, 0x06
+};
+
+/* acpi_amba_dsm_lookup()
+ *
+ * Helper to parse through ACPI _DSM object for a device. Each entry
+ * has three fields.
+ */
+int acpi_amba_dsm_lookup(acpi_handle handle,
+		const char *tag, int index,
+		struct acpi_amba_dsm_entry *entry)
+{
+	acpi_status status;
+	struct acpi_object_list input;
+	struct acpi_buffer output = { ACPI_ALLOCATE_BUFFER, NULL };
+	union acpi_object params[4];
+	union acpi_object *obj;
+	int len, match_count, i;
+
+	/* invalidate output in case there's no entry to supply */
+	entry->key = NULL;
+	entry->value = NULL;
+
+	if (!acpi_has_method(handle, "_DSM"))
+		return -ENOENT;
+
+	input.count = 4;
+	params[0].type = ACPI_TYPE_BUFFER;		/* UUID */
+	params[0].buffer.length = sizeof(acpi_amba_dsm_uuid);
+	params[0].buffer.pointer = (char *)acpi_amba_dsm_uuid;
+	params[1].type = ACPI_TYPE_INTEGER;		/* Revision */
+	params[1].integer.value = 1;
+	params[2].type = ACPI_TYPE_INTEGER;		/* Function # */
+	params[2].integer.value = 1;
+	params[3].type = ACPI_TYPE_PACKAGE;		/* Arguments */
+	params[3].package.count = 0;
+	params[3].package.elements = NULL;
+	input.pointer = params;
+
+	status = acpi_evaluate_object_typed(handle, "_DSM",
+			&input, &output, ACPI_TYPE_PACKAGE);
+	if (ACPI_FAILURE(status)) {
+		pr_err("failed to get _DSM package for this device\n");
+		return -ENOENT;
+	}
+
+	obj = (union acpi_object *)output.pointer;
+
+	/* parse 2 objects per entry */
+	match_count = 0;
+	for (i = 0; (i + 2) <= obj->package.count; i += 2) {
+		/* key must be a string */
+		len = obj->package.elements[i].string.length;
+		if (len <= 0)
+			continue;
+
+		/* check to see if this is the entry to return */
+		if (strncmp(tag, obj->package.elements[i].string.pointer,
+				len) != 0 ||
+				match_count < index) {
+			match_count++;
+			continue;
+		}
+
+		/* copy the key */
+		entry->key = kmalloc(len + 1, GFP_KERNEL);
+		strncpy(entry->key,
+				obj->package.elements[i].string.pointer,
+				len);
+		entry->key[len] = '\0';
+
+		/* value is a string with space-delimited fields if necessary */
+		len = obj->package.elements[i + 1].string.length;
+		if (len > 0) {
+			entry->value = kmalloc(len + 1, GFP_KERNEL);
+			strncpy(entry->value,
+				obj->package.elements[i+1].string.pointer,
+				len);
+			entry->value[len] = '\0';
+		}
+
+		break;
+	}
+
+	kfree(output.pointer);
+
+	if (entry->key == NULL)
+		return -ENOENT;
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(acpi_amba_dsm_lookup);
+
+static int acpi_amba_add_resource(struct acpi_resource *ares, void *data)
+{
+	struct amba_device *dev = data;
+	struct resource r;
+	int irq_idx;
+
+	switch (ares->type) {
+	case ACPI_RESOURCE_TYPE_FIXED_MEMORY32:
+		if (!acpi_dev_resource_memory(ares, &dev->res))
+			pr_err("failed to map memory resource\n");
+		break;
+	case ACPI_RESOURCE_TYPE_EXTENDED_IRQ:
+		for (irq_idx = 0; irq_idx < AMBA_NR_IRQS; irq_idx++) {
+			if (acpi_dev_resource_interrupt(ares, irq_idx, &r))
+				dev->irq[irq_idx] = r.start;
+			else
+				break;
+		}
+
+		break;
+	case ACPI_RESOURCE_TYPE_END_TAG:
+		/* ignore the end tag */
+		break;
+	default:
+		/* log an error, but proceed with driver probe */
+		pr_err("unhandled acpi resource type= %d\n",
+				ares->type);
+		break;
+	}
+
+	return 1; /* Tell ACPI core that this resource has been handled */
+}
+
+static struct clk *acpi_amba_get_clk(acpi_handle handle, int index,
+		char **clk_name)
+{
+	struct acpi_amba_dsm_entry entry;
+	acpi_handle clk_handle;
+	struct acpi_device *adev, *clk_adev;
+	char *clk_path;
+	struct clk *clk = NULL;
+	int len;
+
+	if (acpi_bus_get_device(handle, &adev)) {
+		pr_err("cannot get device from handle\n");
+		return NULL;
+	}
+
+	/* key=value format for clocks is:
+	 *	"clock-name"="apb_pclk \\_SB.CLK0"
+	 */
+	if (acpi_amba_dsm_lookup(handle, "clock-name", index, &entry) != 0)
+		return NULL;
+
+	/* look under the clock device for the clock that matches the entry */
+	*clk_name = NULL;
+	len = strcspn(entry.value, " ");
+	if (len > 0 && (len + 1) < strlen(entry.value)) {
+		clk_path = entry.value + len + 1;
+		*clk_name = kmalloc(len + 1, GFP_KERNEL);
+		strncpy(*clk_name, entry.value, len);
+		(*clk_name)[len] = '\0';
+		if (ACPI_FAILURE(
+			acpi_get_handle(NULL, clk_path, &clk_handle)) == 0 &&
+			acpi_bus_get_device(clk_handle, &clk_adev) == 0)
+			clk = clk_get_sys(dev_name(&clk_adev->dev), *clk_name);
+	} else
+		pr_err("Invalid clock-name value format '%s' for %s\n",
+				entry.value, dev_name(&adev->dev));
+
+	kfree(entry.key);
+	kfree(entry.value);
+
+	return clk;
+}
+
+static void acpi_amba_register_clocks(struct acpi_device *adev,
+		struct clk *default_clk, const char *default_clk_name)
+{
+	struct clk *clk;
+	int i;
+	char *clk_name;
+
+	if (default_clk) {
+		/* for amba_get_enable_pclk() ... */
+		clk_register_clkdev(default_clk, default_clk_name,
+				dev_name(&adev->dev));
+		/* for devm_clk_get() ... */
+		clk_register_clkdev(default_clk, NULL, dev_name(&adev->dev));
+	}
+
+	for (i = 0;; i++) {
+		clk_name = NULL;
+		clk = acpi_amba_get_clk(ACPI_HANDLE(&adev->dev), i, &clk_name);
+		if (!clk)
+			break;
+
+		clk_register_clkdev(clk, clk_name, dev_name(&adev->dev));
+
+		kfree(clk_name);
+	}
+}
+
+/* acpi_amba_add_device()
+ *
+ * ACPI equivalent to of_amba_device_create()
+ */
+static acpi_status acpi_amba_add_device(acpi_handle handle,
+				u32 lvl_not_used, void *data, void **not_used)
+{
+	struct list_head resource_list;
+	struct acpi_device *adev;
+	struct amba_device *dev;
+	int ret;
+	struct acpi_amba_bus_info *bus_info = data;
+	struct platform_device *bus_pdev = bus_info->pdev;
+
+	if (acpi_bus_get_device(handle, &adev)) {
+		pr_err("%s: acpi_bus_get_device failed\n", __func__);
+		return AE_OK;
+	}
+
+	pr_debug("Creating amba device %s\n", dev_name(&adev->dev));
+
+	dev = amba_device_alloc(NULL, 0, 0);
+	if (!dev) {
+		pr_err("%s(): amba_device_alloc() failed for %s\n",
+		       __func__, dev_name(&adev->dev));
+		return AE_CTRL_TERMINATE;
+	}
+
+	/* setup generic device info */
+	dev->dev.coherent_dma_mask = ~0;
+	dev->dev.parent = &bus_pdev->dev;
+	dev_set_name(&dev->dev, "%s", dev_name(&adev->dev));
+
+	/* setup amba-specific device info */
+	ACPI_COMPANION_SET(&dev->dev, adev);
+	ACPI_COMPANION_SET(&adev->dev, adev);
+
+	INIT_LIST_HEAD(&resource_list);
+	acpi_dev_get_resources(adev, &resource_list,
+				     acpi_amba_add_resource, dev);
+	acpi_dev_free_resource_list(&resource_list);
+
+	/* Add clocks */
+	acpi_amba_register_clocks(adev, bus_info->clk, bus_info->clk_name);
+
+	/* Read AMBA hardware ID and add device to system. If a driver matching
+	 *	hardware ID has already been registered, bind this device to it.
+	 *	Otherwise, the platform subsystem will match up the hardware ID
+	 *	when the matching driver is registered.
+	*/
+	ret = amba_device_add(dev, &iomem_resource);
+	if (ret) {
+		pr_err("%s(): amba_device_add() failed (%d) for %s\n",
+		       __func__, ret, dev_name(&adev->dev));
+		goto err_free;
+	}
+
+	return AE_OK;
+
+err_free:
+	amba_device_put(dev);
+
+	return AE_OK; /* don't prevent other devices from being probed */
+}
+
+static int acpi_amba_bus_probe(struct platform_device *pdev)
+{
+	struct acpi_amba_bus_info bus_info;
+	bus_info.clk_name = NULL;
+
+	/* see if there's a top-level clock to use as default for sub-devices */
+	bus_info.clk = acpi_amba_get_clk(ACPI_HANDLE(&pdev->dev), 0,
+			&bus_info.clk_name);
+
+	/* probe each device */
+	bus_info.pdev = pdev;
+	acpi_walk_namespace(ACPI_TYPE_DEVICE, ACPI_HANDLE(&pdev->dev), 1,
+			acpi_amba_add_device, NULL, &bus_info, NULL);
+
+	kfree(bus_info.clk_name);
+
+	return 0;
+}
+
+static const struct acpi_device_id amba_bus_acpi_match[] = {
+	{ "AMBA0000", 0 },
+	{ },
+};
+
+static struct platform_driver amba_bus_acpi_driver = {
+	.driver = {
+		.name = "amba-acpi",
+		.owner = THIS_MODULE,
+		.acpi_match_table = ACPI_PTR(amba_bus_acpi_match),
+	},
+	.probe	= acpi_amba_bus_probe,
+};
+
+static int __init acpi_amba_bus_init(void)
+{
+	return platform_driver_register(&amba_bus_acpi_driver);
+}
+
+postcore_initcall(acpi_amba_bus_init);
+
+MODULE_AUTHOR("Brandon Anderson <brandon.anderson@amd.com>");
+MODULE_DESCRIPTION("ACPI Connector Resource for AMBA bus");
+MODULE_LICENSE("GPLv2");
+MODULE_ALIAS("platform:amba-acpi");
+
+#endif /* CONFIG_ACPI */
diff --git a/include/linux/amba/acpi.h b/include/linux/amba/acpi.h
new file mode 100644
index 000000000000..40a72b2a09d2
--- /dev/null
+++ b/include/linux/amba/acpi.h
@@ -0,0 +1,29 @@
+/*
+ * AMBA bus ACPI helpers
+ *
+ * Copyright (C) 2013 Advanced Micro Devices, Inc.
+ *
+ * Author: Brandon Anderson <brandon.anderson@amd.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.
+ */
+#ifndef __ARM_AMBA_ACPI_H__
+#define __ARM_AMBA_ACPI_H__
+
+#ifdef CONFIG_ACPI
+#include <linux/acpi.h>
+
+struct acpi_amba_dsm_entry {
+	char *key;
+	char *value;
+};
+
+int acpi_amba_dsm_lookup(acpi_handle handle,
+		const char *tag, int index,
+		struct acpi_amba_dsm_entry *entry);
+
+#endif
+
+#endif