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    Subject[PATCH 2/6] drivers/base: add bus for System-on-Chip devices
    Date
    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>
    ---
    drivers/base/Kconfig | 3 +
    drivers/base/Makefile | 1 +
    drivers/base/soc.c | 115 +++++++++++++++++++++++++++++++++++++++++++++++
    include/linux/sys_soc.h | 38 +++++++++++++++
    4 files changed, 157 insertions(+), 0 deletions(-)
    create mode 100644 drivers/base/soc.c
    create mode 100644 include/linux/sys_soc.h
    diff --git a/drivers/base/Kconfig b/drivers/base/Kconfig
    index 21cf46f..707aeaf 100644
    --- a/drivers/base/Kconfig
    +++ b/drivers/base/Kconfig
    @@ -172,6 +172,9 @@ config SYS_HYPERVISOR
    bool
    default n

    +config SOC_BUS
    + bool
    +
    source "drivers/base/regmap/Kconfig"

    endmenu
    diff --git a/drivers/base/Makefile b/drivers/base/Makefile
    index 99a375a..6b84b36 100644
    --- a/drivers/base/Makefile
    +++ b/drivers/base/Makefile
    @@ -18,6 +18,7 @@ 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

    diff --git a/drivers/base/soc.c b/drivers/base/soc.c
    new file mode 100644
    index 0000000..1578e4e
    --- /dev/null
    +++ b/drivers/base/soc.c
    @@ -0,0 +1,115 @@
    +/*
    + * 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/sys_soc.h>
    +#include <linux/err.h>
    +
    +static ssize_t soc_info_get(struct device *dev,
    + struct device_attribute *attr,
    + char *buf);
    +
    +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);
    +
    +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;
    +
    +}
    +
    +struct bus_type soc_bus_type = {
    + .name = "soc",
    +};
    +
    +static int __init soc_bus_register(void)
    +{
    + return bus_register(&soc_bus_type);
    +}
    +core_initcall(soc_bus_register);
    +
    +struct attribute *soc_attr[] = {
    + &dev_attr_machine.attr,
    + &dev_attr_family.attr,
    + &dev_attr_soc_id.attr,
    + &dev_attr_revision.attr,
    + NULL,
    +};
    +
    +struct attribute_group soc_attr_group = {
    + .attrs = soc_attr,
    +};
    +
    +struct device *soc_device_register(struct soc_device_attribute *soc_dev_attr)
    +{
    + struct soc_device *soc_dev;
    + static atomic_t soc_device_num = ATOMIC_INIT(0);
    + int ret;
    +
    + soc_dev = kzalloc(sizeof(*soc_dev), GFP_KERNEL);
    + if (!soc_dev)
    + return ERR_PTR(-ENOMEM);
    +
    + soc_dev->attr = soc_dev_attr;
    + soc_dev->dev.bus = &soc_bus_type;
    +
    + dev_set_name(&soc_dev->dev, "soc%d",
    + atomic_inc_return(&soc_device_num) - 1);
    +
    + ret = device_register(&soc_dev->dev);
    + if (ret)
    + goto out1;
    +
    + ret = sysfs_create_group(&soc_dev->dev.kobj, &soc_attr_group);
    + if (ret)
    + goto out2;
    +
    + return &soc_dev->dev;
    +
    +out2:
    + device_unregister(&soc_dev->dev);
    +out1:
    + kfree(soc_dev);
    + kfree(soc_dev->attr);
    + return ERR_PTR(ret);
    +}
    +
    +void soc_device_unregister(struct device *dev)
    +{
    + struct soc_device *soc_dev =
    + container_of(dev, struct soc_device, dev);
    +
    + sysfs_remove_group(&dev->kobj, &soc_attr_group);
    +
    + if (device_is_registered(dev))
    + device_unregister(dev);
    +
    + bus_unregister(&soc_bus_type);
    +
    + kfree(soc_dev->attr);
    + kfree(soc_dev);
    +}
    diff --git a/include/linux/sys_soc.h b/include/linux/sys_soc.h
    new file mode 100644
    index 0000000..2485a0f2
    --- /dev/null
    +++ b/include/linux/sys_soc.h
    @@ -0,0 +1,38 @@
    +/*
    + * 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/kobject.h>
    +#include <linux/device.h>
    +#include <linux/platform_device.h>
    +
    +struct soc_device_attribute {
    + const char *machine;
    + const char *family;
    + const char *revision;
    + const char *soc_id;
    +};
    +
    +struct soc_device {
    + struct device dev;
    + struct soc_device_attribute *attr;
    +};
    +
    +/**
    + * soc_device_register - register SoC as a device
    + * @soc_plat_dev_attr: Attributes passed from platform to be attributed to a SoC
    + */
    +struct 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 device *dev);
    +
    +#endif /* __SOC_BUS_H */
    --
    1.7.5.4


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