core: implement public line update routines

Line info is retrieved from the kernel for the first time
automatically when gpiod_chip_get_line() is called. Then the line
is updated automatically on request/release. If the ioctl fails in the
latter case, the up_to_date flag is set to false.

Expose an interface allowing users to check if a line is up-to-date
and manually update it if needed.

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

diff --git a/core.c b/core.c
index f830189177be50370121620245a3d4770c204987..f582dde5512bd974ba707315c485976f3a83b319 100644 (file)
--- a/core.c
+++ b/core.c
@@ -125,26 +125,15 @@ int gpiod_simple_get_value(const char *device, unsigned int offset)
 
 struct gpiod_line {
        bool requested;
+       bool up_to_date;
        struct gpiod_chip *chip;
        struct gpioline_info info;
        struct gpiohandle_request *req;
 };
 
-static int update_line_info(struct gpiod_line *line,
-                           struct gpiod_chip *chip, unsigned int offset)
+static void line_set_offset(struct gpiod_line *line, unsigned int offset)
 {
-       int status, fd;
-
-       memset(&line->info, 0, sizeof(line->info));
        line->info.line_offset = offset;
-
-       fd = gpiod_chip_get_fd(chip);
-
-       status = gpio_ioctl(fd, GPIO_GET_LINEINFO_IOCTL, &line->info);
-       if (status < 0)
-               return -1;
-
-       return 0;
 }
 
 unsigned int gpiod_line_offset(struct gpiod_line *line)
@@ -190,6 +179,30 @@ bool gpiod_line_is_open_source(struct gpiod_line *line)
        return line->info.flags & GPIOLINE_FLAG_OPEN_SOURCE;
 }
 
+bool gpiod_line_needs_update(struct gpiod_line *line)
+{
+       return !line->up_to_date;
+}
+
+int gpiod_line_update(struct gpiod_line *line)
+{
+       struct gpiod_chip *chip;
+       int status, fd;
+
+       memset(&line->info, 0, sizeof(line->info));
+
+       chip = gpiod_line_get_chip(line);
+       fd = gpiod_chip_get_fd(chip);
+
+       status = gpio_ioctl(fd, GPIO_GET_LINEINFO_IOCTL, &line->info);
+       if (status < 0)
+               return -1;
+
+       line->up_to_date = true;
+
+       return 0;
+}
+
 int gpiod_line_request(struct gpiod_line *line,
                       const char *consumer, int default_val, int flags)
 {
@@ -221,7 +234,7 @@ int gpiod_line_request_bulk(struct gpiod_line_bulk *line_bulk,
 {
        struct gpiohandle_request *req;
        struct gpiod_chip *chip;
-       unsigned int i, j;
+       unsigned int i;
        int status, fd;
 
        /* Paranoia: verify that all lines are from the same gpiochip. */
@@ -283,13 +296,9 @@ int gpiod_line_request_bulk(struct gpiod_line_bulk *line_bulk,
                 * Update line info to include the changes after the
                 * request.
                 */
-               status = update_line_info(line_bulk->lines[i], chip,
-                               gpiod_line_offset(line_bulk->lines[i]));
-               if (status < 0) {
-                       for (j = 0; j < i; j++)
-                               gpiod_line_release(line_bulk->lines[i]);
-                       return -1;
-               }
+               status = gpiod_line_update(line_bulk->lines[i]);
+               if (status < 0)
+                       line_bulk->lines[i]->up_to_date = false;
        }
 
        return 0;
@@ -308,6 +317,7 @@ void gpiod_line_release(struct gpiod_line *line)
 void gpiod_line_release_bulk(struct gpiod_line_bulk *line_bulk)
 {
        unsigned int i;
+       int status;
 
        close(line_bulk->lines[0]->req->fd);
        free(line_bulk->lines[0]->req);
@@ -315,6 +325,10 @@ void gpiod_line_release_bulk(struct gpiod_line_bulk *line_bulk)
        for (i = 0; i < line_bulk->num_lines; i++) {
                line_bulk->lines[i]->req = NULL;
                line_bulk->lines[i]->requested = false;
+
+               status = gpiod_line_update(line_bulk->lines[i]);
+               if (status < 0)
+                       line_bulk->lines[i]->up_to_date = false;
        }
 }
 
@@ -539,9 +553,10 @@ gpiod_chip_get_line(struct gpiod_chip *chip, unsigned int offset)
        }
 
        line = &chip->lines[offset];
+       line_set_offset(line, offset);
        line->chip = chip;
 
-       status = update_line_info(line, chip, offset);
+       status = gpiod_line_update(line);
        if (status < 0)
                return NULL;
 

diff --git a/gpiod.h b/gpiod.h
index 51b81ddd30f3becd3ba74901fd2d196306a0ce6d..6104cce5ab10405c552613e6a7e8fab1fe841374 100644 (file)
--- a/gpiod.h
+++ b/gpiod.h
@@ -86,6 +86,10 @@ bool gpiod_line_is_open_drain(struct gpiod_line *line) GPIOD_API;
 
 bool gpiod_line_is_open_source(struct gpiod_line *line) GPIOD_API;
 
+bool gpiod_line_needs_update(struct gpiod_line *line) GPIOD_API;
+
+int gpiod_line_update(struct gpiod_line *line) GPIOD_API;
+
 int gpiod_line_request(struct gpiod_line *line, const char *consumer,
                       int default_val, int flags) GPIOD_API;