[PATCH v3 2/3] platform/x86: think-lmi: Add possible_values for ThinkStation

[Mark Pearson <mpearson-lenovo@xxxxxxxxx>]

ThinkStation platforms don't support the API to return possible_values
but instead embed it in the settings string.

Try and extract this information and set the possible_values attribute
appropriately.

If there aren't any values possible then don't display possible_values.

Signed-off-by: Mark Pearson <mpearson-lenovo@xxxxxxxxx>
---
Changes in V3:
 - Use is_visible attribute to determine if possible_values should be
   available
 - Code got refactored a bit to make compilation cleaner
Changes in V2:
 - Move no value for possible_values handling into show function
 - use kstrndup for allocating string

 drivers/platform/x86/think-lmi.c | 82 ++++++++++++++++++++++----------
 1 file changed, 56 insertions(+), 26 deletions(-)

diff --git a/drivers/platform/x86/think-lmi.c b/drivers/platform/x86/think-lmi.c
index 5fa5451c4802..d89a1c9bdbf1 100644
--- a/drivers/platform/x86/think-lmi.c
+++ b/drivers/platform/x86/think-lmi.c
@@ -917,6 +917,8 @@ static ssize_t display_name_show(struct kobject *kobj, struct kobj_attribute *at
 	return sysfs_emit(buf, "%s\n", setting->display_name);
 }
 
+static struct kobj_attribute attr_displ_name = __ATTR_RO(display_name);
+
 static ssize_t current_value_show(struct kobject *kobj, struct kobj_attribute *attr, char *buf)
 {
 	struct tlmi_attr_setting *setting = to_tlmi_attr_setting(kobj);
@@ -937,30 +939,6 @@ static ssize_t current_value_show(struct kobject *kobj, struct kobj_attribute *a
 	return ret;
 }
 
-static ssize_t possible_values_show(struct kobject *kobj, struct kobj_attribute *attr, char *buf)
-{
-	struct tlmi_attr_setting *setting = to_tlmi_attr_setting(kobj);
-
-	if (!tlmi_priv.can_get_bios_selections)
-		return -EOPNOTSUPP;
-
-	return sysfs_emit(buf, "%s\n", setting->possible_values);
-}
-
-static ssize_t type_show(struct kobject *kobj, struct kobj_attribute *attr,
-		char *buf)
-{
-	struct tlmi_attr_setting *setting = to_tlmi_attr_setting(kobj);
-
-	if (setting->possible_values) {
-		/* Figure out what setting type is as BIOS does not return this */
-		if (strchr(setting->possible_values, ','))
-			return sysfs_emit(buf, "enumeration\n");
-	}
-	/* Anything else is going to be a string */
-	return sysfs_emit(buf, "string\n");
-}
-
 static ssize_t current_value_store(struct kobject *kobj,
 		struct kobj_attribute *attr,
 		const char *buf, size_t count)
@@ -1044,14 +1022,46 @@ static ssize_t current_value_store(struct kobject *kobj,
 	return ret ?: count;
 }
 
-static struct kobj_attribute attr_displ_name = __ATTR_RO(display_name);
+static struct kobj_attribute attr_current_val = __ATTR_RW_MODE(current_value, 0600);
+
+static ssize_t possible_values_show(struct kobject *kobj, struct kobj_attribute *attr, char *buf)
+{
+	struct tlmi_attr_setting *setting = to_tlmi_attr_setting(kobj);
+
+	return sysfs_emit(buf, "%s\n", setting->possible_values);
+}
 
 static struct kobj_attribute attr_possible_values = __ATTR_RO(possible_values);
 
-static struct kobj_attribute attr_current_val = __ATTR_RW_MODE(current_value, 0600);
+static ssize_t type_show(struct kobject *kobj, struct kobj_attribute *attr,
+		char *buf)
+{
+	struct tlmi_attr_setting *setting = to_tlmi_attr_setting(kobj);
+
+	if (setting->possible_values) {
+		/* Figure out what setting type is as BIOS does not return this */
+		if (strchr(setting->possible_values, ','))
+			return sysfs_emit(buf, "enumeration\n");
+	}
+	/* Anything else is going to be a string */
+	return sysfs_emit(buf, "string\n");
+}
 
 static struct kobj_attribute attr_type = __ATTR_RO(type);
 
+static umode_t attr_is_visible(struct kobject *kobj,
+					     struct attribute *attr, int n)
+{
+	struct tlmi_attr_setting *setting = to_tlmi_attr_setting(kobj);
+
+	/* We don't want to display possible_values attributes if not available */
+	if (attr == (struct attribute *)&attr_possible_values)
+		if (!setting->possible_values)
+			return 0;
+
+	return attr->mode;
+}
+
 static struct attribute *tlmi_attrs[] = {
 	&attr_displ_name.attr,
 	&attr_current_val.attr,
@@ -1061,6 +1071,7 @@ static struct attribute *tlmi_attrs[] = {
 };
 
 static const struct attribute_group tlmi_attr_group = {
+	.is_visible = attr_is_visible,
 	.attrs = tlmi_attrs,
 };
 
@@ -1440,6 +1451,25 @@ static int tlmi_analyze(void)
 			if (ret || !setting->possible_values)
 				pr_info("Error retrieving possible values for %d : %s\n",
 						i, setting->display_name);
+		} else {
+			/*
+			 * Older Thinkstations don't support the bios_selections API.
+			 * Instead they store this as a [Optional:Option1,Option2] section of the
+			 * name string.
+			 * Try and pull that out if it's available.
+			 */
+			char *item, *optstart, *optend;
+
+			if (!tlmi_setting(setting->index, &item, LENOVO_BIOS_SETTING_GUID)) {
+				optstart = strstr(item, "[Optional:");
+				if (optstart) {
+					optstart += strlen("[Optional:");
+					optend = strstr(optstart, "]");
+					if (optend)
+						setting->possible_values =
+							kstrndup(optstart, optend - optstart, GFP_KERNEL);
+				}
+			}
 		}
 		kobject_init(&setting->kobj, &tlmi_attr_setting_ktype);
 		tlmi_priv.setting[i] = setting;
-- 
2.39.2