linux-kernel - [PATCH 2/2] firmware: dmi-sysfs: add SMBIOS entry point area attribute

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Message-Id: <1422044507-22982-3-git-send-email-ivan.khoronzhuk@linaro.org>
Date:	Fri, 23 Jan 2015 22:21:47 +0200
From:	Ivan Khoronzhuk <ivan.khoronzhuk@...aro.org>
To:	linux-kernel@...r.kernel.org, ard.biesheuvel@...aro.org
Cc:	dmidecode-devel@...gnu.org, grant.likely@...aro.org,
	leif.lindholm@...aro.org, matt.fleming@...el.com,
	Ivan Khoronzhuk <ivan.khoronzhuk@...aro.org>
Subject: [PATCH 2/2] firmware: dmi-sysfs: add SMBIOS entry point area attribute

There are situations when code needs to access SMBIOS entry table
area, but cannot use /dev/mem for this. As the table format is
consistent only for a version, and can be changed, use binary
attribute to give access to raw SMBIOS entry table area.

Signed-off-by: Ivan Khoronzhuk <ivan.khoronzhuk@...aro.org>
---
 drivers/firmware/dmi-sysfs.c | 42 ++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 42 insertions(+)

diff --git a/drivers/firmware/dmi-sysfs.c b/drivers/firmware/dmi-sysfs.c
index e0f1cb3..b5c0558 100644
--- a/drivers/firmware/dmi-sysfs.c
+++ b/drivers/firmware/dmi-sysfs.c
@@ -46,6 +46,8 @@ struct dmi_sysfs_entry {
 static LIST_HEAD(entry_list);
 static DEFINE_SPINLOCK(entry_list_lock);
 
+static unsigned char smbios_raw_header[32];
+
 /* dmi_sysfs_attribute - Top level attribute. used by all entries. */
 struct dmi_sysfs_attribute {
 	struct attribute attr;
@@ -646,9 +648,37 @@ static void cleanup_entry_list(void)
 	}
 }
 
+static ssize_t smbios_entry_area_raw_read(struct file *filp,
+					  struct kobject *kobj,
+					  struct bin_attribute *bin_attr,
+					  char *buf, loff_t pos, size_t count)
+{
+	ssize_t size;
+
+	size = bin_attr->size;
+
+	if (size > pos)
+		size -= pos;
+	else
+		return 0;
+
+	if (count < size)
+		size = count;
+
+	memcpy(buf, &smbios_raw_header[pos], size);
+
+	return size;
+}
+
+static struct bin_attribute smbios_entry_area_raw_attr = {
+	.read = smbios_entry_area_raw_read,
+	.attr = {.name = "smbios_raw_header", .mode = 0400},
+};
+
 static int __init dmi_sysfs_init(void)
 {
 	int error = -ENOMEM;
+	int size;
 	int val;
 
 	/* Set up our directory */
@@ -669,6 +699,18 @@ static int __init dmi_sysfs_init(void)
 		goto err;
 	}
 
+	size = dmi_get_smbios_entry_area(smbios_raw_header);
+	if (size == -ENODATA) {
+		pr_debug("dmi-sysfs: SMBIOS raw data is not available.\n");
+		error = size;
+		goto err;
+	}
+
+	/* Create the raw binary file to access the entry area */
+	smbios_entry_area_raw_attr.size = size;
+	if (sysfs_create_bin_file(dmi_kobj, &smbios_entry_area_raw_attr))
+		goto err;
+
 	pr_debug("dmi-sysfs: loaded.\n");
 
 	return 0;
-- 
1.9.1

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