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Devices on the Intel Lynxpoint Low Power Subsystem (LPSS) have some common features that aren't shared with any other platform devices, including the clock and LTR (Latency Tolerance Reporting) registers. It is better to handle those features in common code than to bother device drivers with doing that (I/O functionality-wise the LPSS devices are generally compatible with other devices that don't have those special registers and may be handled by the same drivers). The clock registers of the LPSS devices are now taken care of by the special clk-x86-lpss driver, but the MMIO mappings used for accessing those registers can also be used for accessing the LTR registers on those devices (LTR support for the Lynxpoint LPSS is going to be added by a subsequent patch). Thus it is convenient to add a special ACPI scan handler for the Lynxpoint LPSS devices that will create the MMIO mappings for accessing the clock (and LTR in the future) registers and will register the LPSS devices' clocks, so the clk-x86-lpss driver will only need to take care of the main Lynxpoint LPSS clock. Introduce a special ACPI scan handler for Intel Lynxpoint LPSS devices as described above. This also reduces overhead related to browsing the ACPI namespace in search of the LPSS devices before the registration of their clocks, removes some LPSS-specific (and somewhat ugly) code from acpi_platform.c and shrinks the overall code size slightly. Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Acked-by: Mike Turquette <mturquette@linaro.org>
129 lines
3.5 KiB
C
129 lines
3.5 KiB
C
/*
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* ACPI support for platform bus type.
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*
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* Copyright (C) 2012, Intel Corporation
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* Authors: Mika Westerberg <mika.westerberg@linux.intel.com>
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* Mathias Nyman <mathias.nyman@linux.intel.com>
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* Rafael J. Wysocki <rafael.j.wysocki@intel.com>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*/
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#include <linux/acpi.h>
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#include <linux/device.h>
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#include <linux/err.h>
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#include <linux/kernel.h>
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#include <linux/module.h>
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#include <linux/platform_device.h>
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#include "internal.h"
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ACPI_MODULE_NAME("platform");
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/*
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* The following ACPI IDs are known to be suitable for representing as
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* platform devices.
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*/
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static const struct acpi_device_id acpi_platform_device_ids[] = {
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{ "PNP0D40" },
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{ }
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};
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/**
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* acpi_create_platform_device - Create platform device for ACPI device node
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* @adev: ACPI device node to create a platform device for.
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* @id: ACPI device ID used to match @adev.
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*
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* Check if the given @adev can be represented as a platform device and, if
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* that's the case, create and register a platform device, populate its common
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* resources and returns a pointer to it. Otherwise, return %NULL.
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*
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* Name of the platform device will be the same as @adev's.
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*/
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int acpi_create_platform_device(struct acpi_device *adev,
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const struct acpi_device_id *id)
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{
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struct platform_device *pdev = NULL;
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struct acpi_device *acpi_parent;
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struct platform_device_info pdevinfo;
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struct resource_list_entry *rentry;
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struct list_head resource_list;
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struct resource *resources;
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int count;
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/* If the ACPI node already has a physical device attached, skip it. */
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if (adev->physical_node_count)
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return 0;
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INIT_LIST_HEAD(&resource_list);
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count = acpi_dev_get_resources(adev, &resource_list, NULL, NULL);
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if (count <= 0)
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return 0;
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resources = kmalloc(count * sizeof(struct resource), GFP_KERNEL);
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if (!resources) {
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dev_err(&adev->dev, "No memory for resources\n");
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acpi_dev_free_resource_list(&resource_list);
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return -ENOMEM;
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}
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count = 0;
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list_for_each_entry(rentry, &resource_list, node)
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resources[count++] = rentry->res;
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acpi_dev_free_resource_list(&resource_list);
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memset(&pdevinfo, 0, sizeof(pdevinfo));
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/*
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* If the ACPI node has a parent and that parent has a physical device
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* attached to it, that physical device should be the parent of the
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* platform device we are about to create.
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*/
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pdevinfo.parent = NULL;
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acpi_parent = adev->parent;
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if (acpi_parent) {
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struct acpi_device_physical_node *entry;
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struct list_head *list;
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mutex_lock(&acpi_parent->physical_node_lock);
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list = &acpi_parent->physical_node_list;
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if (!list_empty(list)) {
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entry = list_first_entry(list,
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struct acpi_device_physical_node,
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node);
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pdevinfo.parent = entry->dev;
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}
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mutex_unlock(&acpi_parent->physical_node_lock);
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}
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pdevinfo.name = dev_name(&adev->dev);
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pdevinfo.id = -1;
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pdevinfo.res = resources;
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pdevinfo.num_res = count;
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pdevinfo.acpi_node.handle = adev->handle;
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pdev = platform_device_register_full(&pdevinfo);
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if (IS_ERR(pdev)) {
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dev_err(&adev->dev, "platform device creation failed: %ld\n",
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PTR_ERR(pdev));
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pdev = NULL;
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} else {
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dev_dbg(&adev->dev, "created platform device %s\n",
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dev_name(&pdev->dev));
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}
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kfree(resources);
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return 1;
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}
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static struct acpi_scan_handler platform_handler = {
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.ids = acpi_platform_device_ids,
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.attach = acpi_create_platform_device,
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};
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void __init acpi_platform_init(void)
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{
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acpi_scan_add_handler(&platform_handler);
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}
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