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: Lee Jones <lee.jones@linaro.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Lee Jones
Greg Kroah-Hartman
parent
956563362b
commit
74d1d82cda
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@ -176,6 +176,9 @@ config GENERIC_CPU_DEVICES
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bool
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default n
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config SOC_BUS
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bool
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source "drivers/base/regmap/Kconfig"
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config DMA_SHARED_BUFFER
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@ -19,6 +19,7 @@ obj-$(CONFIG_MODULES) += module.o
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endif
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obj-$(CONFIG_SYS_HYPERVISOR) += hypervisor.o
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obj-$(CONFIG_REGMAP) += regmap/
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obj-$(CONFIG_SOC_BUS) += soc.o
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ccflags-$(CONFIG_DEBUG_DRIVER) := -DDEBUG
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@ -0,0 +1,183 @@
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/*
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* Copyright (C) ST-Ericsson SA 2011
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*
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* Author: Lee Jones <lee.jones@linaro.org> for ST-Ericsson.
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* License terms: GNU General Public License (GPL), version 2
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*/
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#include <linux/sysfs.h>
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#include <linux/module.h>
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#include <linux/init.h>
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#include <linux/stat.h>
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#include <linux/slab.h>
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#include <linux/idr.h>
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#include <linux/spinlock.h>
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#include <linux/sys_soc.h>
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#include <linux/err.h>
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static DEFINE_IDR(soc_ida);
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static DEFINE_SPINLOCK(soc_lock);
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static ssize_t soc_info_get(struct device *dev,
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struct device_attribute *attr,
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char *buf);
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struct soc_device {
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struct device dev;
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struct soc_device_attribute *attr;
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int soc_dev_num;
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};
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static struct bus_type soc_bus_type = {
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.name = "soc",
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};
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static DEVICE_ATTR(machine, S_IRUGO, soc_info_get, NULL);
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static DEVICE_ATTR(family, S_IRUGO, soc_info_get, NULL);
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static DEVICE_ATTR(soc_id, S_IRUGO, soc_info_get, NULL);
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static DEVICE_ATTR(revision, S_IRUGO, soc_info_get, NULL);
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struct device *soc_device_to_device(struct soc_device *soc_dev)
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{
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return &soc_dev->dev;
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}
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static mode_t soc_attribute_mode(struct kobject *kobj,
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struct attribute *attr,
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int index)
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{
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struct device *dev = container_of(kobj, struct device, kobj);
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struct soc_device *soc_dev = container_of(dev, struct soc_device, dev);
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if ((attr == &dev_attr_machine.attr)
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&& (soc_dev->attr->machine != NULL))
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return attr->mode;
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if ((attr == &dev_attr_family.attr)
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&& (soc_dev->attr->family != NULL))
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return attr->mode;
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if ((attr == &dev_attr_revision.attr)
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&& (soc_dev->attr->revision != NULL))
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return attr->mode;
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if ((attr == &dev_attr_soc_id.attr)
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&& (soc_dev->attr->soc_id != NULL))
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return attr->mode;
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/* Unknown or unfilled attribute. */
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return 0;
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}
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static ssize_t soc_info_get(struct device *dev,
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struct device_attribute *attr,
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char *buf)
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{
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struct soc_device *soc_dev = container_of(dev, struct soc_device, dev);
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if (attr == &dev_attr_machine)
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return sprintf(buf, "%s\n", soc_dev->attr->machine);
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if (attr == &dev_attr_family)
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return sprintf(buf, "%s\n", soc_dev->attr->family);
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if (attr == &dev_attr_revision)
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return sprintf(buf, "%s\n", soc_dev->attr->revision);
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if (attr == &dev_attr_soc_id)
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return sprintf(buf, "%s\n", soc_dev->attr->soc_id);
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return -EINVAL;
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}
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static struct attribute *soc_attr[] = {
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&dev_attr_machine.attr,
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&dev_attr_family.attr,
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&dev_attr_soc_id.attr,
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&dev_attr_revision.attr,
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NULL,
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};
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static const struct attribute_group soc_attr_group = {
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.attrs = soc_attr,
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.is_visible = soc_attribute_mode,
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};
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static const struct attribute_group *soc_attr_groups[] = {
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&soc_attr_group,
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NULL,
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};
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static void soc_release(struct device *dev)
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{
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struct soc_device *soc_dev = container_of(dev, struct soc_device, dev);
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kfree(soc_dev);
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}
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struct soc_device *soc_device_register(struct soc_device_attribute *soc_dev_attr)
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{
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struct soc_device *soc_dev;
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int ret;
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soc_dev = kzalloc(sizeof(*soc_dev), GFP_KERNEL);
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if (!soc_dev) {
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ret = -ENOMEM;
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goto out1;
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}
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/* Fetch a unique (reclaimable) SOC ID. */
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do {
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if (!ida_pre_get(&soc_ida, GFP_KERNEL)) {
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ret = -ENOMEM;
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goto out2;
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}
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spin_lock(&soc_lock);
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ret = ida_get_new(&soc_ida, &soc_dev->soc_dev_num);
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spin_unlock(&soc_lock);
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} while (ret == -EAGAIN);
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if (ret)
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goto out2;
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soc_dev->attr = soc_dev_attr;
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soc_dev->dev.bus = &soc_bus_type;
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soc_dev->dev.groups = soc_attr_groups;
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soc_dev->dev.release = soc_release;
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dev_set_name(&soc_dev->dev, "soc%d", soc_dev->soc_dev_num);
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ret = device_register(&soc_dev->dev);
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if (ret)
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goto out3;
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return soc_dev;
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out3:
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ida_remove(&soc_ida, soc_dev->soc_dev_num);
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out2:
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kfree(soc_dev);
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out1:
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return ERR_PTR(ret);
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}
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/* Ensure soc_dev->attr is freed prior to calling soc_device_unregister. */
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void soc_device_unregister(struct soc_device *soc_dev)
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{
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ida_remove(&soc_ida, soc_dev->soc_dev_num);
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device_unregister(&soc_dev->dev);
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}
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static int __init soc_bus_register(void)
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{
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spin_lock_init(&soc_lock);
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return bus_register(&soc_bus_type);
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}
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core_initcall(soc_bus_register);
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static void __exit soc_bus_unregister(void)
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{
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ida_destroy(&soc_ida);
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bus_unregister(&soc_bus_type);
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}
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module_exit(soc_bus_unregister);
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@ -0,0 +1,37 @@
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/*
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* Copyright (C) ST-Ericsson SA 2011
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* Author: Lee Jones <lee.jones@linaro.org> for ST-Ericsson.
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* License terms: GNU General Public License (GPL), version 2
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*/
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#ifndef __SOC_BUS_H
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#define __SOC_BUS_H
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#include <linux/device.h>
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struct soc_device_attribute {
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const char *machine;
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const char *family;
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const char *revision;
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const char *soc_id;
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};
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/**
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* soc_device_register - register SoC as a device
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* @soc_plat_dev_attr: Attributes passed from platform to be attributed to a SoC
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*/
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struct soc_device *soc_device_register(
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struct soc_device_attribute *soc_plat_dev_attr);
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/**
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* soc_device_unregister - unregister SoC device
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* @dev: SoC device to be unregistered
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*/
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void soc_device_unregister(struct soc_device *soc_dev);
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/**
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* soc_device_to_device - helper function to fetch struct device
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* @soc: Previously registered SoC device container
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*/
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struct device *soc_device_to_device(struct soc_device *soc);
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#endif /* __SOC_BUS_H */
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