gpio: store reflect the label to userspace

The gpio_chip label is useful for userspace to understand what
kind of GPIO chip it is dealing with. Let's store a copy of this
label in the gpio_device, add it to the struct passed to userspace
for GPIO_GET_CHIPINFO_IOCTL and modify lsgpio to show it.

Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

5 files changed, 22 insertions, 3 deletions

diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c
index 59f0045c5950..797c790aa750 100644
--- a/drivers/gpio/gpiolib.c
+++ b/drivers/gpio/gpiolib.c
@@ -342,6 +342,9 @@ static long gpio_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
                 strncpy(chipinfo.name, dev_name(&gdev->dev),
                         sizeof(chipinfo.name));
                 chipinfo.name[sizeof(chipinfo.name)-1] = '\0';
+                strncpy(chipinfo.label, gdev->label,
+                        sizeof(chipinfo.label));
+                chipinfo.label[sizeof(chipinfo.label)-1] = '\0';
                 chipinfo.lines = gdev->ngpio;
                 if (copy_to_user(ip, &chipinfo, sizeof(chipinfo)))
                         return -EFAULT;
@@ -479,6 +482,16 @@ int gpiochip_add_data(struct gpio_chip *chip, void *data)
                 status = -EINVAL;
                 goto err_free_gdev;
         }
+
+        if (chip->label)
+                gdev->label = devm_kstrdup(&gdev->dev, chip->label, GFP_KERNEL);
+        else
+                gdev->label = devm_kstrdup(&gdev->dev, "unknown", GFP_KERNEL);
+        if (!gdev->label) {
+                status = -ENOMEM;
+                goto err_free_gdev;
+        }
+
         gdev->ngpio = chip->ngpio;
         gdev->data = data;
 
diff --git a/drivers/gpio/gpiolib.h b/drivers/gpio/gpiolib.h
index ddbe409ad48f..e30e5fdb1214 100644
--- a/drivers/gpio/gpiolib.h
+++ b/drivers/gpio/gpiolib.h
@@ -37,6 +37,8 @@ struct acpi_device;
  * of the @descs array.
  * @base: GPIO base in the DEPRECATED global Linux GPIO numberspace, assigned
  * at device creation time.
+ * @label: a descriptive name for the GPIO device, such as the part number
+ * or name of the IP component in a System on Chip.
  * @data: per-instance data assigned by the driver
  * @list: links gpio_device:s together for traversal
  *
@@ -55,6 +57,7 @@ struct gpio_device {
         struct gpio_desc        *descs;
         int                     base;
         u16                     ngpio;
+        char                    *label;
         void                    *data;
         struct list_head        list;
 
diff --git a/include/linux/gpio/driver.h b/include/linux/gpio/driver.h
index ff96d0f9fceb..639607658ed8 100644
--- a/include/linux/gpio/driver.h
+++ b/include/linux/gpio/driver.h
@@ -21,7 +21,8 @@ struct gpio_device;
 
 /**
  * struct gpio_chip - abstract a GPIO controller
- * @label: for diagnostics
+ * @label: a functional name for the GPIO device, such as a part
+ *      number or the name of the SoC IP-block implementing it.
  * @gpiodev: the internal state holder, opaque struct
  * @parent: optional parent device providing the GPIOs
  * @owner: helps prevent removal of modules exporting active GPIOs
diff --git a/include/uapi/linux/gpio.h b/include/uapi/linux/gpio.h
index 3188a87bdaa0..3f93e1bcd3dd 100644
--- a/include/uapi/linux/gpio.h
+++ b/include/uapi/linux/gpio.h
@@ -16,10 +16,12 @@
 /**
  * struct gpiochip_info - Information about a certain GPIO chip
  * @name: the name of this GPIO chip
+ * @label: a functional name for this GPIO chip
  * @lines: number of GPIO lines on this chip
  */
 struct gpiochip_info {
         char name[32];
+        char label[32];
         __u32 lines;
 };
 
diff --git a/tools/gpio/lsgpio.c b/tools/gpio/lsgpio.c
index 4cfe29da279b..692233f561fb 100644
--- a/tools/gpio/lsgpio.c
+++ b/tools/gpio/lsgpio.c
@@ -54,8 +54,8 @@ int list_device(const char *device_name)
 
                 goto free_chrdev_name;
         }
-        fprintf(stdout, "GPIO chip: %s, %u GPIO lines\n",
-                cinfo.name, cinfo.lines);
+        fprintf(stdout, "GPIO chip: %s, \"%s\", %u GPIO lines\n",
+                cinfo.name, cinfo.label, cinfo.lines);
 
         if (close(fd) == -1)  {
                 ret = -errno;