On Fri, Mar 11, 2011 at 03:32:51PM +0100, Arnd Bergmann wrote:

On Friday 11 March 2011, Maxime Coquelin wrote:

quoted

Common base to export System-on-Chip related informations through sysfs.

Creation of a "socinfo" directory under /sys/.
Creation of SoC information entries.

Signed-off-by: Maxime COQUELIN <redacted>

I think it's better than the previous patch to create an
artificial device in /sys/devices/system/socinfo, but I'd
still prefer the information to be attached to a real device
that represents the SOC, as I explained in the discussion with
Linus Walleij.

Why not create it under the cpu directory?
 

You should definitely add Greg on Cc, as he's maintaining sysfs
and certainly has an opininion here.

	Arnd

quoted

---
 Documentation/ABI/testing/sysfs-socinfo |   16 ++++++
 drivers/base/Kconfig                    |    3 +
 drivers/base/Makefile                   |    1 +
 drivers/base/soc.c                      |   79 +++++++++++++++++++++++++++++++
 include/linux/sys_soc.h                 |   50 +++++++++++++++++++
 5 files changed, 149 insertions(+), 0 deletions(-)
 create mode 100644 Documentation/ABI/testing/sysfs-socinfo
 create mode 100644 drivers/base/soc.c
 create mode 100644 include/linux/sys_soc.h

diff --git a/Documentation/ABI/testing/sysfs-socinfo b/Documentation/ABI/testing/sysfs-socinfo
new file mode 100644
index 0000000..afd9da2
--- /dev/null
+++ b/Documentation/ABI/testing/sysfs-socinfo

@@ -0,0 +1,16 @@
+What:		/sys/socinfo
+Date:		March 2011
+contact:	Maxime Coquelin <maxime.coquelin-nonst@stericsson.com>
+Description:
+		The /sys/socinfo directory contains information about the
+		System-on-Chip.	It is only available if platform implements it.
+		This directory contains two kind of attributes :
+			- common attributes: 
+				* machine: the name of the machine.
+				* family: the family name of the SoC
+			- SoC-specific attributes: The SoC vendor can declare attributes
+			  to export some strings to user-space, like the serial-number for
+			  example.
+
+Users:
+		User-space applications which needs these kind of attributes.

diff --git a/drivers/base/Kconfig b/drivers/base/Kconfig
index d57e8d0..372ef3a 100644
--- a/drivers/base/Kconfig
+++ b/drivers/base/Kconfig

@@ -168,4 +168,7 @@ config SYS_HYPERVISOR
 	bool
 	default n
 
+config SYS_SOC
+	bool
+
 endmenu

diff --git a/drivers/base/Makefile b/drivers/base/Makefile
index 5f51c3b..f3bcfb3 100644
--- a/drivers/base/Makefile
+++ b/drivers/base/Makefile

@@ -18,6 +18,7 @@ ifeq ($(CONFIG_SYSFS),y)
 obj-$(CONFIG_MODULES)	+= module.o
 endif
 obj-$(CONFIG_SYS_HYPERVISOR) += hypervisor.o
+obj-$(CONFIG_SYS_SOC) += 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..046b43b
--- /dev/null
+++ b/drivers/base/soc.c

@@ -0,0 +1,79 @@
+/*
+ * Copyright (C) ST-Ericsson SA 2011
+ * Author: Maxime Coquelin <maxime.coquelin-nonst@stericsson.com> 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>
+
+struct kobject *soc_object;
+
+ssize_t show_soc_info(struct kobject *kobj,
+			struct kobj_attribute *attr, char *buf)
+{
+	struct sysfs_soc_info *si = container_of(attr,
+				struct sysfs_soc_info, attr);
+
+	if (si->info)
+		return sprintf(buf, "%s\n", si->info);
+
+	return si->get_info(buf, si);
+}

I think this can be simplified by just letting the soc
register its own show method instead of the get_info function.

quoted

+int __init register_sysfs_soc_info(struct sysfs_soc_info *info, int nb_info)
+{
+	int i, ret;
+
+	for (i = 0; i < nb_info; i++) {
+		ret = sysfs_create_file(soc_object, &info[i].attr.attr);
+		if (ret) {
+			for (i -= 1; i >= 0; i--)
+				sysfs_remove_file(soc_object, &info[i].attr.attr);
+			break;
+		}
+	}
+
+	return ret;
+}
+
+static struct attribute *soc_attrs[] = {
+	NULL,
+};
+
+static struct attribute_group soc_attr_group = {
+	.attrs = soc_attrs,
+};
+
+int __init register_sysfs_soc(struct sysfs_soc_info *info, size_t num)
+{
+	int ret;
+
+	soc_object = kobject_create_and_add("socinfo", NULL);
+	if (!soc_object) {
+		ret = -ENOMEM;
+		goto exit;
+	}
+
+	ret = sysfs_create_group(soc_object, &soc_attr_group);
+	if (ret)
+		goto kset_exit;
+
+	ret = register_sysfs_soc_info(info, num);
+	if (ret)
+		goto group_exit;
+
+	return 0;
+
+group_exit:
+	sysfs_remove_group(soc_object, &soc_attr_group);
+kset_exit:
+	kobject_put(soc_object);
+exit:
+	return ret;
+}
+

diff --git a/include/linux/sys_soc.h b/include/linux/sys_soc.h
new file mode 100644
index 0000000..05e5529
--- /dev/null
+++ b/include/linux/sys_soc.h

@@ -0,0 +1,50 @@
+/*
+ * Copyright (C) ST-Ericsson SA 2011
+ * Author: Maxime Coquelin <maxime.coquelin-nonst@stericsson.com> for ST-Ericsson.
+ * License terms:  GNU General Public License (GPL), version 2
+ */
+#ifndef __SYS_SOC_H
+#define __SYS_SOC_H
+
+#include <linux/kobject.h>
+
+/**
+ * struct sys_soc_info - SoC exports related informations
+ * @name: name of the export
+ * @info: pointer on the key to export
+ * @get_info: callback to retrieve key if info field is NULL
+ * @attr: export's sysdev class attribute
+ */
+struct sysfs_soc_info {
+	const char *info;
+	ssize_t (*get_info)(char *buf, struct sysfs_soc_info *);
+	struct kobj_attribute attr;
+};
+
+ssize_t show_soc_info(struct kobject *, struct kobj_attribute *, char *);
+
+#define SYSFS_SOC_ATTR_VALUE(_name, _value) {		\
+	.attr.attr.name = _name,			\
+	.attr.attr.mode = S_IRUGO,			\
+	.attr.show	= show_soc_info,		\
+	.info           = _value,			\
+}
+
+#define SYSFS_SOC_ATTR_CALLBACK(_name, _callback) {	\
+	.attr.attr.name = _name,			\
+	.attr.attr.mode = S_IRUGO,			\
+	.attr.show	= show_soc_info,		\
+	.get_info       = _callback,			\
+}
+
+/**
+ * register_sys_soc - register the soc information
+ * @name: name of the machine
+ * @info: pointer on the info table to export
+ * @num: number of info to export
+ *
+ * NOTE: This function must only be called once
+ */
+int register_sysfs_soc(struct sysfs_soc_info *info, size_t num);
+
+#endif /* __SYS_SOC_H */

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-- 
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