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SubjectRe: [Patch v2 2/3] firmware: dmi_scan: add SBMIOS entry and DMI tables
From
On Mon, Apr 20, 2015 at 3:19 AM, Ivan Khoronzhuk
<ivan.khoronzhuk@globallogic.com> wrote:
> Some utils, like dmidecode and smbios, need to access SMBIOS entry
> table area in order to get information like SMBIOS version, size, etc.
> Currently it's done via /dev/mem. But for situation when /dev/mem
> usage is disabled, the utils have to use dmi sysfs instead, which
> doesn't represent SMBIOS entry and adds code/delay redundancy when direct
> access for table is needed.
>
> So this patch creates dmi/tables and adds SMBIOS entry point to allow
> utils in question to work correctly without /dev/mem. Also patch adds
> raw dmi table to simplify dmi table processing in user space, as
> proposed by Jean Delvare.
>
> Signed-off-by: Ivan Khoronzhuk <ivan.khoronzhuk@globallogic.com>

Tested-by: Roy Franz <roy.franz@linaro.org>

Tested with dmidecode w/patches to read tables from sysfs. The dmidecode
patches are posted on dmidecode-devel and should be commited upstream soon.

Thanks,
Roy

> ---
> .../ABI/testing/sysfs-firmware-dmi-tables | 22 ++++++
> drivers/firmware/dmi-sysfs.c | 17 +++--
> drivers/firmware/dmi_scan.c | 82 ++++++++++++++++++++++
> include/linux/dmi.h | 2 +
> 4 files changed, 114 insertions(+), 9 deletions(-)
> create mode 100644 Documentation/ABI/testing/sysfs-firmware-dmi-tables
>
> diff --git a/Documentation/ABI/testing/sysfs-firmware-dmi-tables b/Documentation/ABI/testing/sysfs-firmware-dmi-tables
> new file mode 100644
> index 0000000..ff3cac8
> --- /dev/null
> +++ b/Documentation/ABI/testing/sysfs-firmware-dmi-tables
> @@ -0,0 +1,22 @@
> +What: /sys/firmware/dmi/tables/
> +Date: April 2015
> +Contact: Ivan Khoronzhuk <ivan.khoronzhuk@globallogic.com>
> +Description:
> + The firmware provides DMI structures as a packed list of
> + data referenced by a SMBIOS table entry point. The SMBIOS
> + entry point contains general information, like SMBIOS
> + version, DMI table size, etc. The structure, content and
> + size of SMBIOS entry point is dependent on SMBIOS version.
> + The format of SMBIOS entry point and DMI structures
> + can be read in SMBIOS specification.
> +
> + The dmi/tables provides raw SMBIOS entry point and DMI tables
> + through sysfs as an alternative to utilities reading them
> + from /dev/mem. The raw SMBIOS entry point and DMI table are
> + presented as binary attributes and are accessible via:
> +
> + /sys/firmware/dmi/tables/smbios_entry_point
> + /sys/firmware/dmi/tables/DMI
> +
> + The complete DMI information can be obtained using these two
> + tables.
> diff --git a/drivers/firmware/dmi-sysfs.c b/drivers/firmware/dmi-sysfs.c
> index e0f1cb3..ef76e5e 100644
> --- a/drivers/firmware/dmi-sysfs.c
> +++ b/drivers/firmware/dmi-sysfs.c
> @@ -566,7 +566,6 @@ static struct kobj_type dmi_sysfs_entry_ktype = {
> .default_attrs = dmi_sysfs_entry_attrs,
> };
>
> -static struct kobject *dmi_kobj;
> static struct kset *dmi_kset;
>
> /* Global count of all instances seen. Only for setup */
> @@ -648,17 +647,20 @@ static void cleanup_entry_list(void)
>
> static int __init dmi_sysfs_init(void)
> {
> - int error = -ENOMEM;
> + int error;
> int val;
>
> - /* Set up our directory */
> - dmi_kobj = kobject_create_and_add("dmi", firmware_kobj);
> - if (!dmi_kobj)
> + if (!dmi_kobj) {
> + pr_err("dmi-sysfs: dmi entry is absent.\n");
> + error = -ENODATA;
> goto err;
> + }
>
> dmi_kset = kset_create_and_add("entries", NULL, dmi_kobj);
> - if (!dmi_kset)
> + if (!dmi_kset) {
> + error = -ENOMEM;
> goto err;
> + }
>
> val = 0;
> error = dmi_walk(dmi_sysfs_register_handle, &val);
> @@ -675,7 +677,6 @@ static int __init dmi_sysfs_init(void)
> err:
> cleanup_entry_list();
> kset_unregister(dmi_kset);
> - kobject_put(dmi_kobj);
> return error;
> }
>
> @@ -685,8 +686,6 @@ static void __exit dmi_sysfs_exit(void)
> pr_debug("dmi-sysfs: unloading.\n");
> cleanup_entry_list();
> kset_unregister(dmi_kset);
> - kobject_del(dmi_kobj);
> - kobject_put(dmi_kobj);
> }
>
> module_init(dmi_sysfs_init);
> diff --git a/drivers/firmware/dmi_scan.c b/drivers/firmware/dmi_scan.c
> index a864a6b..9705be2 100644
> --- a/drivers/firmware/dmi_scan.c
> +++ b/drivers/firmware/dmi_scan.c
> @@ -10,6 +10,9 @@
> #include <asm/dmi.h>
> #include <asm/unaligned.h>
>
> +struct kobject *dmi_kobj;
> +EXPORT_SYMBOL_GPL(dmi_kobj);
> +
> /*
> * DMI stands for "Desktop Management Interface". It is part
> * of and an antecedent to, SMBIOS, which stands for System
> @@ -20,6 +23,9 @@ static const char dmi_empty_string[] = " ";
> static u32 dmi_ver __initdata;
> static u32 dmi_len;
> static u16 dmi_num;
> +static u8 smbios_entry_point[32];
> +static int smbios_entry_point_size;
> +
> /*
> * Catch too early calls to dmi_check_system():
> */
> @@ -478,6 +484,8 @@ static int __init dmi_present(const u8 *buf)
> if (memcmp(buf, "_SM_", 4) == 0 &&
> buf[5] < 32 && dmi_checksum(buf, buf[5])) {
> smbios_ver = get_unaligned_be16(buf + 6);
> + smbios_entry_point_size = buf[5];
> + memcpy(smbios_entry_point, buf, smbios_entry_point_size);
>
> /* Some BIOS report weird SMBIOS version, fix that up */
> switch (smbios_ver) {
> @@ -512,6 +520,9 @@ static int __init dmi_present(const u8 *buf)
> pr_info("SMBIOS %d.%d present.\n",
> dmi_ver >> 8, dmi_ver & 0xFF);
> } else {
> + smbios_entry_point_size = 15;
> + memcpy(smbios_entry_point, buf,
> + smbios_entry_point_size);
> pr_info("Legacy DMI %d.%d present.\n",
> dmi_ver >> 8, dmi_ver & 0xFF);
> }
> @@ -538,6 +549,8 @@ static int __init dmi_smbios3_present(const u8 *buf)
> dmi_num = 0; /* No longer specified */
> dmi_len = get_unaligned_le32(buf + 12);
> dmi_base = get_unaligned_le64(buf + 16);
> + smbios_entry_point_size = buf[6];
> + memcpy(smbios_entry_point, buf, smbios_entry_point_size);
>
> if (dmi_walk_early(dmi_decode) == 0) {
> pr_info("SMBIOS %d.%d.%d present.\n",
> @@ -629,6 +642,75 @@ void __init dmi_scan_machine(void)
> dmi_initialized = 1;
> }
>
> +static ssize_t raw_table_read(struct file *file, struct kobject *kobj,
> + struct bin_attribute *attr, char *buf,
> + loff_t pos, size_t count)
> +{
> + memcpy(buf, attr->private + pos, count);
> + return count;
> +}
> +
> +static BIN_ATTR(smbios_entry_point, S_IRUSR, raw_table_read, NULL, 0);
> +static BIN_ATTR(DMI, S_IRUSR, raw_table_read, NULL, 0);
> +
> +static int __init dmi_init(void)
> +{
> + int ret;
> + u8 *dmi_table = NULL;
> + struct kobject *tables_kobj = NULL;
> +
> + if (!dmi_available) {
> + ret = -ENODATA;
> + goto err;
> + }
> +
> + /*
> + * Set up dmi directory at /sys/firmware/dmi. This entry should stay
> + * even after farther error, as it can be used by other modules like
> + * dmi-sysfs.
> + */
> + dmi_kobj = kobject_create_and_add("dmi", firmware_kobj);
> + tables_kobj = kobject_create_and_add("tables", dmi_kobj);
> + if (!(dmi_kobj && tables_kobj)) {
> + ret = -ENOMEM;
> + goto err;
> + }
> +
> + bin_attr_smbios_entry_point.size = smbios_entry_point_size;
> + bin_attr_smbios_entry_point.private = smbios_entry_point;
> + ret = sysfs_create_bin_file(tables_kobj, &bin_attr_smbios_entry_point);
> + if (ret)
> + goto err;
> +
> + dmi_table = dmi_remap(dmi_base, dmi_len);
> + if (!dmi_table) {
> + ret = -ENOMEM;
> + goto err;
> + }
> +
> + bin_attr_DMI.size = dmi_len;
> + bin_attr_DMI.private = dmi_table;
> + ret = sysfs_create_bin_file(tables_kobj, &bin_attr_DMI);
> + if (!ret)
> + return 0;
> +
> +err:
> + pr_err("dmi: Firmware registration failed.\n");
> +
> + if (tables_kobj) {
> + sysfs_remove_bin_file(tables_kobj,
> + &bin_attr_smbios_entry_point);
> + kobject_del(tables_kobj);
> + kobject_put(tables_kobj);
> + }
> +
> + if (dmi_table)
> + dmi_unmap(dmi_table);
> +
> + return ret;
> +}
> +subsys_initcall(dmi_init);
> +
> /**
> * dmi_set_dump_stack_arch_desc - set arch description for dump_stack()
> *
> diff --git a/include/linux/dmi.h b/include/linux/dmi.h
> index f820f0a..2f9f988 100644
> --- a/include/linux/dmi.h
> +++ b/include/linux/dmi.h
> @@ -2,6 +2,7 @@
> #define __DMI_H__
>
> #include <linux/list.h>
> +#include <linux/kobject.h>
> #include <linux/mod_devicetable.h>
>
> /* enum dmi_field is in mod_devicetable.h */
> @@ -93,6 +94,7 @@ struct dmi_dev_onboard {
> int devfn;
> };
>
> +extern struct kobject *dmi_kobj;
> extern int dmi_check_system(const struct dmi_system_id *list);
> const struct dmi_system_id *dmi_first_match(const struct dmi_system_id *list);
> extern const char * dmi_get_system_info(int field);
> --
> 1.9.1
>


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