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Message-Id: <20230926202144.5906-1-fevalle@ipt.br>
Date: Tue, 26 Sep 2023 17:21:44 -0300
From: Fernando Eckhardt Valle <fevalle@....br>
To: ilpo.jarvinen@...ux.intel.com, hdegoede@...hat.com,
mpearson-lenovo@...ebb.ca, corbet@....net, hmh@....eng.br,
markgross@...nel.org, linux-doc@...r.kernel.org,
linux-kernel@...r.kernel.org, ibm-acpi-devel@...ts.sourceforge.net,
platform-driver-x86@...r.kernel.org
Subject: [PATCH v6] platform/x86: thinkpad_acpi: sysfs interface to auxmac
Newer Thinkpads have a feature called MAC Address Pass-through.
This patch provides a sysfs interface that userspace can use
to get this auxiliary mac address.
Signed-off-by: Fernando Eckhardt Valle <fevalle@....br>
---
Changes in v6:
- New adjustment to the strcpy() offset.
- Added is_visible attribute.
Changes in v5:
- Repeated code deleted.
- Adjusted offset of a strscpy().
Changes in v4:
- strscpy() in all string copies.
Changes in v3:
- Added null terminator to auxmac string when copying auxiliary
mac address value.
Changes in v2:
- Added documentation.
- All handling of the auxmac value is done in the _init function.
---
.../admin-guide/laptops/thinkpad-acpi.rst | 20 +++++
drivers/platform/x86/thinkpad_acpi.c | 88 +++++++++++++++++++
2 files changed, 108 insertions(+)
diff --git a/Documentation/admin-guide/laptops/thinkpad-acpi.rst b/Documentation/admin-guide/laptops/thinkpad-acpi.rst
index e27a1c3f6..98d304010 100644
--- a/Documentation/admin-guide/laptops/thinkpad-acpi.rst
+++ b/Documentation/admin-guide/laptops/thinkpad-acpi.rst
@@ -53,6 +53,7 @@ detailed description):
- Lap mode sensor
- Setting keyboard language
- WWAN Antenna type
+ - Auxmac
A compatibility table by model and feature is maintained on the web
site, http://ibm-acpi.sf.net/. I appreciate any success or failure
@@ -1511,6 +1512,25 @@ Currently 2 antenna types are supported as mentioned below:
The property is read-only. If the platform doesn't have support the sysfs
class is not created.
+Auxmac
+------
+
+sysfs: auxmac
+
+Some newer Thinkpads have a feature called MAC Address Pass-through. This
+feature is implemented by the system firmware to provide a system unique MAC,
+that can override a dock or USB ethernet dongle MAC, when connected to a
+network. This property enables user-space to easily determine the MAC address
+if the feature is enabled.
+
+The values of this auxiliary MAC are:
+
+ cat /sys/devices/platform/thinkpad_acpi/auxmac
+
+If the feature is disabled, the value will be 'disabled'.
+
+This property is read-only.
+
Adaptive keyboard
-----------------
diff --git a/drivers/platform/x86/thinkpad_acpi.c b/drivers/platform/x86/thinkpad_acpi.c
index d70c89d32..9c19624a7 100644
--- a/drivers/platform/x86/thinkpad_acpi.c
+++ b/drivers/platform/x86/thinkpad_acpi.c
@@ -10785,6 +10785,89 @@ static struct ibm_struct dprc_driver_data = {
.name = "dprc",
};
+/*
+ * Auxmac
+ *
+ * This auxiliary mac address is enabled in the bios through the
+ * MAC Address Pass-through feature. In most cases, there are three
+ * possibilities: Internal Mac, Second Mac, and disabled.
+ *
+ */
+
+#define AUXMAC_LEN 12
+#define AUXMAC_START 9
+#define AUXMAC_STRLEN 22
+#define AUXMAC_BEGIN_MARKER 8
+#define AUXMAC_END_MARKER 21
+
+static char auxmac[AUXMAC_LEN + 1];
+
+static int auxmac_init(struct ibm_init_struct *iibm)
+{
+ acpi_status status;
+ struct acpi_buffer buffer = { ACPI_ALLOCATE_BUFFER, NULL };
+ union acpi_object *obj;
+
+ status = acpi_evaluate_object(NULL, "\\MACA", NULL, &buffer);
+
+ if (ACPI_FAILURE(status))
+ return -ENODEV;
+
+ obj = buffer.pointer;
+
+ if (obj->type != ACPI_TYPE_STRING || obj->string.length != AUXMAC_STRLEN) {
+ pr_info("Invalid buffer for MAC address pass-through.\n");
+ goto auxmacinvalid;
+ }
+
+ if (obj->string.pointer[AUXMAC_BEGIN_MARKER] != '#' ||
+ obj->string.pointer[AUXMAC_END_MARKER] != '#') {
+ pr_info("Invalid header for MAC address pass-through.\n");
+ goto auxmacinvalid;
+ }
+
+ if (strncmp(obj->string.pointer + AUXMAC_START, "XXXXXXXXXXXX", AUXMAC_LEN) != 0)
+ strscpy(auxmac, obj->string.pointer + AUXMAC_START, sizeof(auxmac));
+ else
+ strscpy(auxmac, "disabled", sizeof(auxmac));
+
+free:
+ kfree(obj);
+ return 0;
+
+auxmacinvalid:
+ strscpy(auxmac, "unavailable", sizeof(auxmac));
+ goto free;
+}
+
+static struct ibm_struct auxmac_data = {
+ .name = "auxmac",
+};
+
+static ssize_t auxmac_show(struct device *dev,
+ struct device_attribute *attr,
+ char *buf)
+{
+ return sysfs_emit(buf, "%s\n", auxmac);
+}
+static DEVICE_ATTR_RO(auxmac);
+
+static umode_t auxmac_attr_is_visible(struct kobject *kobj,
+ struct attribute *attr, int n)
+{
+ return auxmac[0] == 0 ? 0 : attr->mode;
+}
+
+static struct attribute *auxmac_attributes[] = {
+ &dev_attr_auxmac.attr,
+ NULL
+};
+
+static const struct attribute_group auxmac_attr_group = {
+ .is_visible = auxmac_attr_is_visible,
+ .attrs = auxmac_attributes,
+};
+
/* --------------------------------------------------------------------- */
static struct attribute *tpacpi_driver_attributes[] = {
@@ -10843,6 +10926,7 @@ static const struct attribute_group *tpacpi_groups[] = {
&proxsensor_attr_group,
&kbdlang_attr_group,
&dprc_attr_group,
+ &auxmac_attr_group,
NULL,
};
@@ -11414,6 +11498,10 @@ static struct ibm_init_struct ibms_init[] __initdata = {
.init = tpacpi_dprc_init,
.data = &dprc_driver_data,
},
+ {
+ .init = auxmac_init,
+ .data = &auxmac_data,
+ },
};
static int __init set_ibm_param(const char *val, const struct kernel_param *kp)
--
2.25.1
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