[PATCH] platform/x86: think-lmi: add debug_cmd

[Mark Pearson <markpearson@lenovo.com>]

Many Lenovo BIOS's support the ability to send a debug command which
is useful for debugging and testing unreleased or early features.
Adding support for this feature.

Also moved the pending_reboot node under attributes dir where it should
correctly live. Got that wrong in my last commit and realised as I was
updating the documentation for debug_cmd

Signed-off-by: Mark Pearson <markpearson@lenovo.com>
---
 .../testing/sysfs-class-firmware-attributes   | 11 +++
 drivers/platform/x86/think-lmi.c              | 77 ++++++++++++++++++-
 drivers/platform/x86/think-lmi.h              |  1 +
 3 files changed, 88 insertions(+), 1 deletion(-)

diff --git a/Documentation/ABI/testing/sysfs-class-firmware-attributes b/Documentation/ABI/testing/sysfs-class-firmware-attributes
index 3348bf80a37c..db0aa2939efc 100644
--- a/Documentation/ABI/testing/sysfs-class-firmware-attributes
+++ b/Documentation/ABI/testing/sysfs-class-firmware-attributes
@@ -272,3 +272,14 @@ Description:
 
 		Note that any changes to this attribute requires a reboot
 		for changes to take effect.
+
+What:		/sys/class/firmware-attributes/*/attributes/debug_cmd
+Date:		July 2021
+KernelVersion:	5.14
+Contact:	Mark Pearson <markpearson@lenovo.com>
+Description:
+		This write only attribute can be used to send debug commands to the BIOS.
+		This should only be used when recommended by the BIOS vendor. Vendors may
+		use it to enable extra debug attributes or BIOS features for testing purposes.
+
+		Note that any changes to this attribute requires a reboot for changes to take effect.
diff --git a/drivers/platform/x86/think-lmi.c b/drivers/platform/x86/think-lmi.c
index 64dcec53a7a0..d58d4b155139 100644
--- a/drivers/platform/x86/think-lmi.c
+++ b/drivers/platform/x86/think-lmi.c
@@ -116,6 +116,14 @@
  */
 #define LENOVO_GET_BIOS_SELECTIONS_GUID	"7364651A-132F-4FE7-ADAA-40C6C7EE2E3B"
 
+/*
+ * Name:
+ *  Lenovo_DebugCmdGUID
+ * Description
+ *  Debug entry GUID method for entering debug commands to the BIOS
+ */
+#define LENOVO_DEBUG_CMD_GUID "7FF47003-3B6C-4E5E-A227-E979824A85D1"
+
 #define TLMI_POP_PWD (1 << 0)
 #define TLMI_PAP_PWD (1 << 1)
 #define to_tlmi_pwd_setting(kobj)  container_of(kobj, struct tlmi_pwd_setting, kobj)
@@ -660,6 +668,63 @@ static ssize_t pending_reboot_show(struct kobject *kobj, struct kobj_attribute *
 
 static struct kobj_attribute pending_reboot = __ATTR_RO(pending_reboot);
 
+/* ---- Debug interface--------------------------------------------------------- */
+static ssize_t debug_cmd_store(struct kobject *kobj, struct kobj_attribute *attr,
+				const char *buf, size_t count)
+{
+	char *set_str = NULL, *new_setting = NULL;
+	char *auth_str = NULL;
+	char *p;
+	int ret;
+
+	if (!tlmi_priv.can_debug_cmd)
+		return -EOPNOTSUPP;
+
+	new_setting = kstrdup(buf, GFP_KERNEL);
+	if (!new_setting)
+		return -ENOMEM;
+
+	/* Strip out CR if one is present */
+	p = strchrnul(new_setting, '\n');
+	*p = '\0';
+
+	if (tlmi_priv.pwd_admin->valid && tlmi_priv.pwd_admin->password[0]) {
+		auth_str = kasprintf(GFP_KERNEL, "%s,%s,%s;",
+				tlmi_priv.pwd_admin->password,
+				encoding_options[tlmi_priv.pwd_admin->encoding],
+				tlmi_priv.pwd_admin->kbdlang);
+		if (!auth_str) {
+			ret = -ENOMEM;
+			goto out;
+		}
+	}
+
+	if (auth_str)
+		set_str = kasprintf(GFP_KERNEL, "%s,%s", new_setting, auth_str);
+	else
+		set_str = kasprintf(GFP_KERNEL, "%s;", new_setting);
+	if (!set_str) {
+		ret = -ENOMEM;
+		goto out;
+	}
+
+	ret = tlmi_simple_call(LENOVO_DEBUG_CMD_GUID, set_str);
+	if (ret)
+		goto out;
+
+	if (!ret && !tlmi_priv.pending_changes) {
+		tlmi_priv.pending_changes = true;
+		/* let userland know it may need to check reboot pending again */
+		kobject_uevent(&tlmi_priv.class_dev->kobj, KOBJ_CHANGE);
+	}
+out:
+	kfree(auth_str);
+	kfree(set_str);
+	kfree(new_setting);
+	return ret ?: count;
+}
+static struct kobj_attribute debug_cmd = __ATTR_WO(debug_cmd);
+
 /* ---- Initialisation --------------------------------------------------------- */
 static void tlmi_release_attr(void)
 {
@@ -681,6 +746,8 @@ static void tlmi_release_attr(void)
 	kobject_put(&tlmi_priv.pwd_power->kobj);
 	kset_unregister(tlmi_priv.authentication_kset);
 	sysfs_remove_file(&tlmi_priv.class_dev->kobj, &pending_reboot.attr);
+	if (tlmi_priv.can_debug_cmd)
+		sysfs_remove_file(&tlmi_priv.class_dev->kobj, &debug_cmd.attr);
 }
 
 static int tlmi_sysfs_init(void)
@@ -761,10 +828,15 @@ static int tlmi_sysfs_init(void)
 		goto fail_create_attr;
 
 	/* Create global sysfs files */
-	ret = sysfs_create_file(&tlmi_priv.class_dev->kobj, &pending_reboot.attr);
+	ret = sysfs_create_file(&tlmi_priv.attribute_kset->kobj, &pending_reboot.attr);
 	if (ret)
 		goto fail_create_attr;
 
+	if (tlmi_priv.can_debug_cmd) {
+		ret = sysfs_create_file(&tlmi_priv.attribute_kset->kobj, &debug_cmd.attr);
+		if (ret)
+			goto fail_create_attr;
+	}
 	return ret;
 
 fail_create_attr:
@@ -796,6 +868,9 @@ static int tlmi_analyze(void)
 	if (wmi_has_guid(LENOVO_BIOS_PASSWORD_SETTINGS_GUID))
 		tlmi_priv.can_get_password_settings = true;
 
+	if (wmi_has_guid(LENOVO_DEBUG_CMD_GUID))
+		tlmi_priv.can_debug_cmd = true;
+
 	/*
 	 * Try to find the number of valid settings of this machine
 	 * and use it to create sysfs attributes.
diff --git a/drivers/platform/x86/think-lmi.h b/drivers/platform/x86/think-lmi.h
index eb598846628a..f8e26823075f 100644
--- a/drivers/platform/x86/think-lmi.h
+++ b/drivers/platform/x86/think-lmi.h
@@ -61,6 +61,7 @@ struct think_lmi {
 	bool can_set_bios_password;
 	bool can_get_password_settings;
 	bool pending_changes;
+	bool can_debug_cmd;
 
 	struct tlmi_attr_setting *setting[TLMI_SETTINGS_COUNT];
 	struct device *class_dev;
-- 
2.31.1