Hi Mark,
please also CC linux-kernel@xxxxxxxxxxxxxxx and previous reviewers.
On Fri, Mar 17, 2023 at 11:46:34AM -0400, Mark Pearson wrote:
> 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");
> +}
This patch seems to introduce a lot of churn, is it intentional?
>
> 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)
This cast is unsafe, if the struct kobj_attribute order is randomised it
will break.
You can use
if (attr == &attr_possible_values.attr)
> + 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);
> + }
> + }
The patch now does two things:
1) Hide the sysfs attributes if the value is not available
2) Extract the value from the description
Maybe it could be split in two?
Another observation:
Would it make sense to remove the part
"[Optional:Option1,Option2]" from the name attribute?
> }
> kobject_init(&setting->kobj, &tlmi_attr_setting_ktype);
> tlmi_priv.setting[i] = setting;
> --
> 2.39.2
>
