core: allow to read values of lines configured for events

The kernel allows us to read values of lines on which we're listening
for events, but libgpiod bails out if the user tries to do it.

Modify gpiod_line_get_value_bulk() to select the correct file
descriptor, depending on how the line object is configured and
allow reading values for both normally exported and monitored lines.

Signed-off-by: Bartosz Golaszewski <bartekgola@gmail.com>

diff --git a/src/lib/core.c b/src/lib/core.c
index e4ca720b7156d1e75c544cb98debf4fdfb449185..2d45e357694fbc5d2e58c32af96dabc473e3e021 100644 (file)
--- a/src/lib/core.c
+++ b/src/lib/core.c
@@ -426,6 +426,30 @@ static void line_update(struct gpiod_line *line)
                line_set_needs_update(line);
 }
 
+static bool line_bulk_is_reserved(struct gpiod_line_bulk *line_bulk)
+{
+       unsigned int i;
+
+       for (i = 0; i < line_bulk->num_lines; i++) {
+               if (!gpiod_line_is_reserved(line_bulk->lines[i]))
+                       return false;
+       }
+
+       return true;
+}
+
+static bool line_bulk_is_event_configured(struct gpiod_line_bulk *line_bulk)
+{
+       unsigned int i;
+
+       for (i = 0; i < line_bulk->num_lines; i++) {
+               if (!gpiod_line_event_configured(line_bulk->lines[i]))
+                       return false;
+       }
+
+       return true;
+}
+
 bool gpiod_line_needs_update(struct gpiod_line *line)
 {
        return !line->up_to_date;
@@ -582,18 +606,6 @@ bool gpiod_line_is_free(struct gpiod_line *line)
        return line_get_state(line) == LINE_FREE;
 }
 
-static bool line_bulk_is_reserved(struct gpiod_line_bulk *line_bulk)
-{
-       unsigned int i;
-
-       for (i = 0; i < line_bulk->num_lines; i++) {
-               if (!gpiod_line_is_reserved(line_bulk->lines[i]))
-                       return false;
-       }
-
-       return true;
-}
-
 int gpiod_line_get_value(struct gpiod_line *line)
 {
        struct gpiod_line_bulk bulk;
@@ -612,18 +624,26 @@ int gpiod_line_get_value(struct gpiod_line *line)
 int gpiod_line_get_value_bulk(struct gpiod_line_bulk *bulk, int *values)
 {
        struct gpiohandle_data data;
+       struct gpiod_line *first;
        unsigned int i;
-       int status;
+       int status, fd;
 
-       if (!line_bulk_is_reserved(bulk)) {
+       first = bulk->lines[0];
+
+       if (!line_bulk_is_reserved(bulk) &&
+           !line_bulk_is_event_configured(bulk)) {
                set_last_error(GPIOD_EREQUEST);
                return -1;
        }
 
        memset(&data, 0, sizeof(data));
 
-       status = gpio_ioctl(line_get_handle_fd(bulk->lines[0]),
-                           GPIOHANDLE_GET_LINE_VALUES_IOCTL, &data);
+       if (gpiod_line_is_reserved(first))
+               fd = line_get_handle_fd(first);
+       else
+               fd = line_get_event_fd(first);
+
+       status = gpio_ioctl(fd, GPIOHANDLE_GET_LINE_VALUES_IOCTL, &data);
        if (status < 0)
                return -1;
 
@@ -773,18 +793,6 @@ int gpiod_line_event_wait(struct gpiod_line *line,
        return gpiod_line_event_wait_bulk(&bulk, timeout, NULL);
 }
 
-static bool line_bulk_is_event_configured(struct gpiod_line_bulk *line_bulk)
-{
-       unsigned int i;
-
-       for (i = 0; i < line_bulk->num_lines; i++) {
-               if (!gpiod_line_event_configured(line_bulk->lines[i]))
-                       return false;
-       }
-
-       return true;
-}
-
 int gpiod_line_event_wait_bulk(struct gpiod_line_bulk *bulk,
                               const struct timespec *timeout,
                               struct gpiod_line **line)