diff options
| -rw-r--r-- | Documentation/ABI/testing/sysfs-auxdisplay-linedisp | 11 | ||||
| -rw-r--r-- | drivers/auxdisplay/line-display.c | 11 |
2 files changed, 22 insertions, 0 deletions
diff --git a/Documentation/ABI/testing/sysfs-auxdisplay-linedisp b/Documentation/ABI/testing/sysfs-auxdisplay-linedisp index 45cf4e5a2feb..55f1b559e84e 100644 --- a/Documentation/ABI/testing/sysfs-auxdisplay-linedisp +++ b/Documentation/ABI/testing/sysfs-auxdisplay-linedisp @@ -15,6 +15,17 @@ Description: echo "Hello World" > message cat message # Returns "Hello World\n" +What: /sys/.../num_chars +Date: November 2025 +KernelVersion: 6.18 +Contact: Jean-François Lessard <jefflessard3@gmail.com> +Description: + Read-only attribute showing the character width capacity of + the line display device. Messages longer than this will scroll. + + Example: + cat num_chars # Returns "16\n" for 16-char display + What: /sys/.../scroll_step_ms Date: October 2021 KernelVersion: 5.16 diff --git a/drivers/auxdisplay/line-display.c b/drivers/auxdisplay/line-display.c index 73e4e77ea4f9..7f3e53e2847b 100644 --- a/drivers/auxdisplay/line-display.c +++ b/drivers/auxdisplay/line-display.c @@ -178,6 +178,16 @@ static ssize_t message_store(struct device *dev, struct device_attribute *attr, static DEVICE_ATTR_RW(message); +static ssize_t num_chars_show(struct device *dev, struct device_attribute *attr, + char *buf) +{ + struct linedisp *linedisp = to_linedisp(dev); + + return sysfs_emit(buf, "%u\n", linedisp->num_chars); +} + +static DEVICE_ATTR_RO(num_chars); + static ssize_t scroll_step_ms_show(struct device *dev, struct device_attribute *attr, char *buf) { @@ -240,6 +250,7 @@ static DEVICE_ATTR(map_seg14, 0644, map_seg_show, map_seg_store); static struct attribute *linedisp_attrs[] = { &dev_attr_message.attr, + &dev_attr_num_chars.attr, &dev_attr_scroll_step_ms.attr, &dev_attr_map_seg7.attr, &dev_attr_map_seg14.attr, |