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Commit 74d1d82c authored by Lee Jones's avatar Lee Jones Committed by Greg Kroah-Hartman
Browse files

drivers/base: add bus for System-on-Chip devices 



Traditionally, any System-on-Chip based platform creates a flat list
of platform_devices directly under /sys/devices/platform.

In order to give these some better structure, this introduces a new
bus type for soc_devices that are registered with the new
soc_device_register() function.  All devices that are on the same
chip should then be registered as child devices of the soc device.

The soc bus also exports a few standardised device attributes which
allow user space to query the specific type of soc.

Signed-off-by: default avatarLee Jones <lee.jones@linaro.org>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 95656336

drivers/base/Kconfig

+3 −0
Original line number Diff line number Diff line
@@ -176,6 +176,9 @@ config GENERIC_CPU_DEVICES 
	bool

	default n



config SOC_BUS

	bool



source "drivers/base/regmap/Kconfig"



config DMA_SHARED_BUFFER

drivers/base/Makefile

+1 −0
Original line number Diff line number Diff line
@@ -19,6 +19,7 @@ obj-$(CONFIG_MODULES) += module.o 
endif

obj-$(CONFIG_SYS_HYPERVISOR) += hypervisor.o

obj-$(CONFIG_REGMAP)	+= regmap/

obj-$(CONFIG_SOC_BUS) += soc.o



ccflags-$(CONFIG_DEBUG_DRIVER) := -DDEBUG

drivers/base/soc.c

0 → 100644
+183 −0
Original line number Diff line number Diff line 
/*

 * Copyright (C) ST-Ericsson SA 2011

 *

 * Author: Lee Jones <lee.jones@linaro.org> for ST-Ericsson.

 * License terms:  GNU General Public License (GPL), version 2

 */



#include <linux/sysfs.h>

#include <linux/module.h>

#include <linux/init.h>

#include <linux/stat.h>

#include <linux/slab.h>

#include <linux/idr.h>

#include <linux/spinlock.h>

#include <linux/sys_soc.h>

#include <linux/err.h>



static DEFINE_IDR(soc_ida);

static DEFINE_SPINLOCK(soc_lock);



static ssize_t soc_info_get(struct device *dev,

			    struct device_attribute *attr,

			    char *buf);



struct soc_device {

	struct device dev;

	struct soc_device_attribute *attr;

	int soc_dev_num;

};



static struct bus_type soc_bus_type = {

	.name  = "soc",

};



static DEVICE_ATTR(machine,  S_IRUGO, soc_info_get,  NULL);

static DEVICE_ATTR(family,   S_IRUGO, soc_info_get,  NULL);

static DEVICE_ATTR(soc_id,   S_IRUGO, soc_info_get,  NULL);

static DEVICE_ATTR(revision, S_IRUGO, soc_info_get,  NULL);



struct device *soc_device_to_device(struct soc_device *soc_dev)

{

	return &soc_dev->dev;

}



static mode_t soc_attribute_mode(struct kobject *kobj,

                                 struct attribute *attr,

                                 int index)

{

	struct device *dev = container_of(kobj, struct device, kobj);

	struct soc_device *soc_dev = container_of(dev, struct soc_device, dev);



	if ((attr == &dev_attr_machine.attr)

	    && (soc_dev->attr->machine != NULL))

		return attr->mode;

	if ((attr == &dev_attr_family.attr)

	    && (soc_dev->attr->family != NULL))

		return attr->mode;

	if ((attr == &dev_attr_revision.attr)

	    && (soc_dev->attr->revision != NULL))

		return attr->mode;

	if ((attr == &dev_attr_soc_id.attr)

	    && (soc_dev->attr->soc_id != NULL))

	        return attr->mode;



	/* Unknown or unfilled attribute. */

	return 0;

}



static ssize_t soc_info_get(struct device *dev,

			    struct device_attribute *attr,

			    char *buf)

{

	struct soc_device *soc_dev = container_of(dev, struct soc_device, dev);



	if (attr == &dev_attr_machine)

		return sprintf(buf, "%s\n", soc_dev->attr->machine);

	if (attr == &dev_attr_family)

		return sprintf(buf, "%s\n", soc_dev->attr->family);

	if (attr == &dev_attr_revision)

		return sprintf(buf, "%s\n", soc_dev->attr->revision);

	if (attr == &dev_attr_soc_id)

		return sprintf(buf, "%s\n", soc_dev->attr->soc_id);



	return -EINVAL;



}



static struct attribute *soc_attr[] = {

	&dev_attr_machine.attr,

	&dev_attr_family.attr,

	&dev_attr_soc_id.attr,

	&dev_attr_revision.attr,

	NULL,

};



static const struct attribute_group soc_attr_group = {

	.attrs = soc_attr,

	.is_visible = soc_attribute_mode,

};



static const struct attribute_group *soc_attr_groups[] = {

	&soc_attr_group,

	NULL,

};



static void soc_release(struct device *dev)

{

	struct soc_device *soc_dev = container_of(dev, struct soc_device, dev);



	kfree(soc_dev);

}



struct soc_device *soc_device_register(struct soc_device_attribute *soc_dev_attr)

{

	struct soc_device *soc_dev;

	int ret;



	soc_dev = kzalloc(sizeof(*soc_dev), GFP_KERNEL);

	if (!soc_dev) {

	        ret = -ENOMEM;

		goto out1;

	}



	/* Fetch a unique (reclaimable) SOC ID. */

	do {

		if (!ida_pre_get(&soc_ida, GFP_KERNEL)) {

			ret = -ENOMEM;

			goto out2;

		}



		spin_lock(&soc_lock);

		ret = ida_get_new(&soc_ida, &soc_dev->soc_dev_num);

		spin_unlock(&soc_lock);



	} while (ret == -EAGAIN);



	if (ret)

	         goto out2;



	soc_dev->attr = soc_dev_attr;

	soc_dev->dev.bus = &soc_bus_type;

	soc_dev->dev.groups = soc_attr_groups;

	soc_dev->dev.release = soc_release;



	dev_set_name(&soc_dev->dev, "soc%d", soc_dev->soc_dev_num);



	ret = device_register(&soc_dev->dev);

	if (ret)

		goto out3;



	return soc_dev;



out3:

	ida_remove(&soc_ida, soc_dev->soc_dev_num);

out2:

	kfree(soc_dev);

out1:

	return ERR_PTR(ret);

}



/* Ensure soc_dev->attr is freed prior to calling soc_device_unregister. */

void soc_device_unregister(struct soc_device *soc_dev)

{

	ida_remove(&soc_ida, soc_dev->soc_dev_num);



	device_unregister(&soc_dev->dev);

}



static int __init soc_bus_register(void)

{

	spin_lock_init(&soc_lock);



	return bus_register(&soc_bus_type);

}

core_initcall(soc_bus_register);



static void __exit soc_bus_unregister(void)

{

	ida_destroy(&soc_ida);



	bus_unregister(&soc_bus_type);

}

module_exit(soc_bus_unregister);

include/linux/sys_soc.h

0 → 100644
+37 −0
Original line number Diff line number Diff line 
/*

 * Copyright (C) ST-Ericsson SA 2011

 * Author: Lee Jones <lee.jones@linaro.org> for ST-Ericsson.

 * License terms:  GNU General Public License (GPL), version 2

 */

#ifndef __SOC_BUS_H

#define __SOC_BUS_H



#include <linux/device.h>



struct soc_device_attribute {

	const char *machine;

	const char *family;

	const char *revision;

	const char *soc_id;

};



/**

 * soc_device_register - register SoC as a device

 * @soc_plat_dev_attr: Attributes passed from platform to be attributed to a SoC

 */

struct soc_device *soc_device_register(

	struct soc_device_attribute *soc_plat_dev_attr);



/**

 * soc_device_unregister - unregister SoC device

 * @dev: SoC device to be unregistered

 */

void soc_device_unregister(struct soc_device *soc_dev);



/**

 * soc_device_to_device - helper function to fetch struct device

 * @soc: Previously registered SoC device container

 */

struct device *soc_device_to_device(struct soc_device *soc);



#endif /* __SOC_BUS_H */