I ran into this when working on a keyboard driver for
the Razer family: the .blink_set() callback for setting
hardware blinking on a LED only exist in a non-blocking
(fastpath) variant, such as when blinking can be enabled
by simply writing a memory-mapped register and protected
by spinlocks.
On USB keyboards with blinkable LEDs controlled with USB
out-of-band commands this will of course not work: these
calls need to come from process context.
To support this: add a new .blink_set_blocking() callback
in the same vein as .brightness_set_blocking() and add
a flag and some code to the delayed work so that this
will be able to fire the .blink_set_blocking() call.
ALl of this will be handled transparently from the
led_blink_set() call so all current users can keep
using that.
Signed-off-by: Linus Walleij <linus.walleij@xxxxxxxxxx>
---
drivers/leds/led-core.c | 49 ++++++++++++++++++++++++++++++++++++++---
include/linux/leds.h | 9 ++++++++
2 files changed, 55 insertions(+), 3 deletions(-)
diff --git a/drivers/leds/led-core.c b/drivers/leds/led-core.c
index ede4fa0ac2cc..94870a3d59af 100644
--- a/drivers/leds/led-core.c
+++ b/drivers/leds/led-core.c
@@ -108,6 +108,20 @@ static void set_brightness_delayed(struct work_struct *ws)
container_of(ws, struct led_classdev, set_brightness_work);
int ret = 0;
+ if (test_and_clear_bit(LED_BLINK_HW_SET, &led_cdev->work_flags)) {
+ if (led_cdev->blink_set)
+ ret = led_cdev->blink_set(led_cdev,
+ &led_cdev->blink_delay_on,
+ &led_cdev->blink_delay_off);
+ else if (led_cdev->blink_set_blocking)
+ ret = led_cdev->blink_set_blocking(led_cdev,
+ &led_cdev->blink_delay_on,
+ &led_cdev->blink_delay_off);
+ if (ret)
+ dev_err(led_cdev->dev,
+ "setting hardware blink failed (%d)\n", ret);
+ }
+
if (test_and_clear_bit(LED_BLINK_DISABLE, &led_cdev->work_flags)) {
led_cdev->delayed_set_value = LED_OFF;
led_stop_software_blink(led_cdev);
@@ -157,15 +171,44 @@ static void led_set_software_blink(struct led_classdev *led_cdev,
mod_timer(&led_cdev->blink_timer, jiffies + 1);
}
+static int led_set_hardware_blink_nosleep(struct led_classdev *led_cdev,
+ unsigned long *delay_on,
+ unsigned long *delay_off)
+{
+ /* We have a non-blocking call, use it */
+ if (led_cdev->blink_set)
+ return led_cdev->blink_set(led_cdev, delay_on, delay_off);
+
+ /* Tell the worker to set up the blinking hardware */
+ if (delay_on)
+ led_cdev->blink_delay_on = *delay_on;
+ else
+ led_cdev->blink_delay_on = 0;
+ if (delay_off)
+ led_cdev->blink_delay_off = *delay_off;
+ else
+ led_cdev->blink_delay_off = 0;
+ set_bit(LED_BLINK_HW_SET, &led_cdev->work_flags);
+ schedule_work(&led_cdev->set_brightness_work);
+
+ return 0;
+}
static void led_blink_setup(struct led_classdev *led_cdev,
unsigned long *delay_on,
unsigned long *delay_off)
{
+ /*
+ * If not oneshot, and we have hardware support for blinking,
+ * relay the request to the driver.
+ */
if (!test_bit(LED_BLINK_ONESHOT, &led_cdev->work_flags) &&
- led_cdev->blink_set &&
- !led_cdev->blink_set(led_cdev, delay_on, delay_off))
- return;
+ (led_cdev->blink_set || led_cdev->blink_set_blocking)) {
+ /* If this fails we fall back to software blink */
+ if (!led_set_hardware_blink_nosleep(led_cdev,
+ delay_on, delay_off))
+ return;
+ }
/* blink with 1 Hz as default if nothing specified */
if (!*delay_on && !*delay_off)
diff --git a/include/linux/leds.h b/include/linux/leds.h
index 7393a316d9fa..57f3df0774e7 100644
--- a/include/linux/leds.h
+++ b/include/linux/leds.h
@@ -61,6 +61,7 @@ struct led_classdev {
#define LED_BLINK_INVERT 3
#define LED_BLINK_BRIGHTNESS_CHANGE 4
#define LED_BLINK_DISABLE 5
+#define LED_BLINK_HW_SET 6
/* Set LED brightness level
* Must not sleep. Use brightness_set_blocking for drivers
@@ -88,6 +89,14 @@ struct led_classdev {
int (*blink_set)(struct led_classdev *led_cdev,
unsigned long *delay_on,
unsigned long *delay_off);
+ /*
+ * Set LED blinking immediately but may sleep (block) the caller
+ * to access the LED device register.
+ */
+ int (*blink_set_blocking)(struct led_classdev *led_cdev,
+ unsigned long *delay_on,
+ unsigned long *delay_off);
+
int (*pattern_set)(struct led_classdev *led_cdev,
struct led_pattern *pattern, u32 len, int repeat);
--
2.19.1
