led: Implement software led blinking

If hardware (or driver) doesn't support leds blinking, it's
now possible to use software implementation of blinking instead.
This relies on cyclic functions.

Signed-off-by: Michael Polyntsov <michael.polyntsov@iopsys.eu>
Signed-off-by: Mikhail Kshevetskiy <mikhail.kshevetskiy@iopsys.eu>
Reviewed-by: Simon Glass <sjg@chromium.org>

drivers/led/Kconfig

@@ -65,7 +65,7 @@ config LED_PWM
 	  Linux compatible ofdata.
 
 config LED_BLINK
-	bool "Support LED blinking"
+	bool "Support hardware LED blinking"
 	depends on LED
 	help
 	  Some drivers can support automatic blinking of LEDs with a given
@@ -73,6 +73,20 @@ config LED_BLINK
 	  This option enables support for this which adds slightly to the
 	  code size.
 
+config LED_SW_BLINK
+	bool "Support software LED blinking"
+	depends on LED
+	select CYCLIC
+	help
+	  Turns on led blinking implemented in the software, useful when
+	  the hardware doesn't support led blinking. Half of the period
+	  led will be ON and the rest time it will be OFF. Standard
+	  led commands can be used to configure blinking. Does nothing
+	  if driver supports hardware blinking.
+	  WARNING: Blinking may be inaccurate during execution of time
+	  consuming commands (ex. flash reading). Also it completely
+	  stops during OS booting.
+
 config SPL_LED
 	bool "Enable LED support in SPL"
 	depends on SPL_DM

drivers/led/Makefile

@@ -4,6 +4,7 @@
 # Written by Simon Glass <sjg@chromium.org>
 
 obj-y += led-uclass.o
+obj-$(CONFIG_LED_SW_BLINK) += led_sw_blink.o
 obj-$(CONFIG_LED_BCM6328) += led_bcm6328.o
 obj-$(CONFIG_LED_BCM6358) += led_bcm6358.o
 obj-$(CONFIG_LED_BCM6753) += led_bcm6753.o

drivers/led/led-uclass.c

@@ -58,6 +58,10 @@ int led_set_state(struct udevice *dev, enum led_state_t state)
 	if (!ops->set_state)
 		return -ENOSYS;
 
+	if (IS_ENABLED(CONFIG_LED_SW_BLINK) &&
+	    led_sw_on_state_change(dev, state))
+		return 0;
+
 	return ops->set_state(dev, state);
 }
 
@@ -68,6 +72,10 @@ enum led_state_t led_get_state(struct udevice *dev)
 	if (!ops->get_state)
 		return -ENOSYS;
 
+	if (IS_ENABLED(CONFIG_LED_SW_BLINK) &&
+	    led_sw_is_blinking(dev))
+		return LEDST_BLINK;
+
 	return ops->get_state(dev);
 }
 
@@ -80,6 +88,9 @@ int led_set_period(struct udevice *dev, int period_ms)
 		return ops->set_period(dev, period_ms);
 #endif
 
+	if (IS_ENABLED(CONFIG_LED_SW_BLINK))
+		return led_sw_set_period(dev, period_ms);
+
 	return -ENOSYS;
 }
 

drivers/led/led_sw_blink.c

@@ -0,0 +1,117 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Software blinking helpers
+ * Copyright (C) 2024 IOPSYS Software Solutions AB
+ * Author: Mikhail Kshevetskiy <mikhail.kshevetskiy@iopsys.eu>
+ */
+
+#include <dm.h>
+#include <led.h>
+#include <time.h>
+#include <stdlib.h>
+
+#define CYCLIC_NAME_PREFIX	"led_sw_blink_"
+
+static void led_sw_blink(struct cyclic_info *c)
+{
+	struct led_sw_blink *sw_blink;
+	struct udevice *dev;
+	struct led_ops *ops;
+
+	sw_blink = container_of(c, struct led_sw_blink, cyclic);
+	dev = sw_blink->dev;
+	ops = led_get_ops(dev);
+
+	switch (sw_blink->state) {
+	case LED_SW_BLINK_ST_OFF:
+		sw_blink->state = LED_SW_BLINK_ST_ON;
+		ops->set_state(dev, LEDST_ON);
+		break;
+	case LED_SW_BLINK_ST_ON:
+		sw_blink->state = LED_SW_BLINK_ST_OFF;
+		ops->set_state(dev, LEDST_OFF);
+		break;
+	case LED_SW_BLINK_ST_NOT_READY:
+		/*
+		 * led_set_period has been called, but
+		 * led_set_state(LDST_BLINK) has not yet,
+		 * so doing nothing
+		 */
+		break;
+	default:
+		break;
+	}
+}
+
+int led_sw_set_period(struct udevice *dev, int period_ms)
+{
+	struct led_uc_plat *uc_plat = dev_get_uclass_plat(dev);
+	struct led_sw_blink *sw_blink = uc_plat->sw_blink;
+	struct led_ops *ops = led_get_ops(dev);
+	int half_period_us;
+
+	half_period_us = period_ms * 1000 / 2;
+
+	if (!sw_blink) {
+		int len = sizeof(struct led_sw_blink) +
+			  strlen(CYCLIC_NAME_PREFIX) +
+			  strlen(uc_plat->label) + 1;
+
+		sw_blink = calloc(1, len);
+		if (!sw_blink)
+			return -ENOMEM;
+
+		sw_blink->dev = dev;
+		sw_blink->state = LED_SW_BLINK_ST_DISABLED;
+		strcpy((char *)sw_blink->cyclic_name, CYCLIC_NAME_PREFIX);
+		strcat((char *)sw_blink->cyclic_name, uc_plat->label);
+
+		uc_plat->sw_blink = sw_blink;
+	}
+
+	if (sw_blink->state == LED_SW_BLINK_ST_DISABLED) {
+		cyclic_register(&sw_blink->cyclic, led_sw_blink,
+				half_period_us, sw_blink->cyclic_name);
+	} else {
+		sw_blink->cyclic.delay_us = half_period_us;
+		sw_blink->cyclic.start_time_us = timer_get_us();
+	}
+
+	sw_blink->state = LED_SW_BLINK_ST_NOT_READY;
+	ops->set_state(dev, LEDST_OFF);
+
+	return 0;
+}
+
+bool led_sw_is_blinking(struct udevice *dev)
+{
+	struct led_uc_plat *uc_plat = dev_get_uclass_plat(dev);
+	struct led_sw_blink *sw_blink = uc_plat->sw_blink;
+
+	if (!sw_blink)
+		return false;
+
+	return sw_blink->state > LED_SW_BLINK_ST_NOT_READY;
+}
+
+bool led_sw_on_state_change(struct udevice *dev, enum led_state_t state)
+{
+	struct led_uc_plat *uc_plat = dev_get_uclass_plat(dev);
+	struct led_sw_blink *sw_blink = uc_plat->sw_blink;
+
+	if (!sw_blink || sw_blink->state == LED_SW_BLINK_ST_DISABLED)
+		return false;
+
+	if (state == LEDST_BLINK) {
+		/* start blinking on next led_sw_blink() call */
+		sw_blink->state = LED_SW_BLINK_ST_OFF;
+		return true;
+	}
+
+	/* stop blinking */
+	uc_plat->sw_blink = NULL;
+	cyclic_unregister(&sw_blink->cyclic);
+	free(sw_blink);
+
+	return false;
+}