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Commit 433f9280 authored by Sheetal Sahasrabudhe's avatar Sheetal Sahasrabudhe
Browse files

msm: Add memory mapped interface for counters 



Map the QDSS base address and allow user-space to access it via mmap call.
Add the base address to device tree. Create a character device driver for
the device accessed from user-space.

Change-Id: I76cd542fa9e1b5fc7a6fc9c7cf415351b2c02fed
Signed-off-by: default avatarSheetal Sahasrabudhe <sheetals@codeaurora.org>
parent 86155e46

Documentation/devicetree/bindings/arm/msm/perfmap.txt

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* MSM Perfmap interface for performance monitors



Perfmap provides mapping of the base address for performance monitors and

allows user-space to access it via mmap call. It create a character device

driver which is accessed from user-space.



The required nodes for Perfmap are:



- compatible: "qcom,perfmap"

- reg: base address and size of mapped area



Example:

	qcom,perfmap@0xfc330000 {

		compatible = "qcom,perfmap";

		reg = <0xfc330000 0x3000>;

	};

arch/arm/Kconfig

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@@ -1421,6 +1421,12 @@ config KSAPI 
          Scorpion processor supported hardware performance counters on a per

          thread basis or AXI counters on an overall system basis.



config PERFMAP

        tristate "Perfmap support (EXPERIMENTAL)"

	depends on ARCH_MSM_KRAIT

        help

          Perfmap: memory mapped interface for performance monitors.



endmenu



source "arch/arm/common/Kconfig"

arch/arm/mach-msm/Makefile

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@@ -426,3 +426,4 @@ obj-$(CONFIG_WALL_CLK) += wallclk.o 
obj-$(CONFIG_WALL_CLK_SYSFS) += wallclk_sysfs.o



obj-$(CONFIG_ARCH_RANDOM) += early_random.o

obj-$(CONFIG_PERFMAP) += perfmap.o

arch/arm/mach-msm/perfmap.c

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/* Copyright (c) 2013, The Linux Foundation. All rights reserved.

 *

 * This program is free software; you can redistribute it and/or modify

 * it under the terms of the GNU General Public License version 2 and

 * only version 2 as published by the Free Software Foundation.

 *

 * 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.

 */



/* Character device driver for memory mapped performance counter interface */

#include <linux/slab.h>

#include <linux/mm.h>

#include <linux/fs.h>

#include <linux/cpu_pm.h>

#include <linux/cpu.h>

#include <linux/module.h>

#include <linux/of.h>

#include <linux/platform_device.h>

#include <linux/debugfs.h>

#include <linux/sched.h>

#include <linux/cdev.h>



uint32_t perfmap_base;

uint32_t PERF_BASE_SIZE;





static dev_t perfmap_dev;

static struct cdev perfmap_cdev;

static struct class *perfmap_devclass;



static struct of_device_id perfmap_of_device_ids[] = {

	{.compatible = "qcom,perfmap"},

	{},

};



static int perfmap_device_probe(struct platform_device *pdev)

{

	struct resource *resource;



	resource = platform_get_resource(pdev, IORESOURCE_MEM, 0);

	if (!resource)

		return -EINVAL;

	perfmap_base = resource->start;



	return 0;

}



static struct platform_driver perfmap_pmu_driver = {

	.driver		= {

		.name	= "perfmap",

		.of_match_table = perfmap_of_device_ids,

	},

	.probe		= perfmap_device_probe,

};



static int perfmap_mmap(struct file *filep, struct vm_area_struct *vma)

{

	int ret = 0;

	unsigned long pfn_num;



	pfn_num = perfmap_base>>PAGE_SHIFT;

	vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);

	if (remap_pfn_range(vma, vma->vm_start, pfn_num,

		vma->vm_end-vma->vm_start,

		vma->vm_page_prot)) {

		return -EAGAIN;

	}

	return ret;

}



static const struct file_operations perfmap_fops = {

	.mmap	= perfmap_mmap,

};



static int perfmap_init(void)

{

	int result = 0;



	platform_driver_register(&perfmap_pmu_driver);

	if (alloc_chrdev_region(&perfmap_dev, 0, 1, "perfmap") < 0) {

		pr_err("perfmap: Error in alloc_chrdev_region\n");

		goto alloc_err;

	}

	perfmap_devclass = class_create(THIS_MODULE, "chardrv");

	if (IS_ERR(perfmap_devclass)) {

		pr_err("perfmap: Error in class_create\n");

		goto class_err;

	}

	if (device_create(perfmap_devclass, NULL, perfmap_dev, NULL,

			"perfmap0") == NULL) {

		pr_err("perfmap: Error in device_create\n");

		goto create_err;

	}

	cdev_init(&perfmap_cdev, &perfmap_fops);

	if (cdev_add(&perfmap_cdev, perfmap_dev, 1) == -1) {

		pr_err("perfmap: Error in cdev_add\n");

		goto add_err;

	}

	return result;

add_err:

	device_destroy(perfmap_devclass, perfmap_dev);

create_err:

	class_destroy(perfmap_devclass);

class_err:

	unregister_chrdev_region(perfmap_dev, 1);

alloc_err:

	result = -ENODEV;

	return result;

}



static void perfmap_exit(void)

{

	cdev_del(&perfmap_cdev);

	device_destroy(perfmap_devclass, perfmap_dev);

	class_destroy(perfmap_devclass);

	unregister_chrdev_region(perfmap_dev, 1);

	platform_driver_unregister(&perfmap_pmu_driver);

}



module_init(perfmap_init);

module_exit(perfmap_exit);



MODULE_LICENSE("GPL v2");