Many an ethernet PHY (and other chips) supports various HW control modes
for LEDs connected directly to them.
This patch adds a generic API for registering such LEDs when described
in device tree. This API also exposes generic way to select between
these hardware control modes.
This API registers a new private LED trigger called dev-hw-mode. When
this trigger is enabled for a LED, the various HW control modes which
are supported by the device for given LED can be get/set via hw_mode
sysfs file.
Signed-off-by: Marek Behún <marek.behun@xxxxxx>
---
.../sysfs-class-led-trigger-dev-hw-mode | 8 +
drivers/leds/Kconfig | 10 +
drivers/leds/Makefile | 1 +
drivers/leds/leds-hw-controlled.c | 227 ++++++++++++++++++
include/linux/leds-hw-controlled.h | 74 ++++++
5 files changed, 320 insertions(+)
create mode 100644 Documentation/ABI/testing/sysfs-class-led-trigger-dev-hw-mode
create mode 100644 drivers/leds/leds-hw-controlled.c
create mode 100644 include/linux/leds-hw-controlled.h
diff --git a/Documentation/ABI/testing/sysfs-class-led-trigger-dev-hw-mode b/Documentation/ABI/testing/sysfs-class-led-trigger-dev-hw-mode
new file mode 100644
index 0000000000000..7bca112e7ff93
--- /dev/null
+++ b/Documentation/ABI/testing/sysfs-class-led-trigger-dev-hw-mode
@@ -0,0 +1,8 @@
+What: /sys/class/leds/<led>/hw_mode
+Date: September 2020
+KernelVersion: 5.10
+Contact: Marek Behún <marek.behun@xxxxxx>
+ linux-leds@xxxxxxxxxxxxxxx
+Description: (W) Set the HW control mode of this LED. The various available HW control modes
+ are specific per device to which the LED is connected to and per LED itself.
+ (R) Show the available HW control modes and the currently selected one.
diff --git a/drivers/leds/Kconfig b/drivers/leds/Kconfig
index 1c181df24eae4..5e47ab21aafb4 100644
--- a/drivers/leds/Kconfig
+++ b/drivers/leds/Kconfig
@@ -49,6 +49,16 @@ config LEDS_BRIGHTNESS_HW_CHANGED
See Documentation/ABI/testing/sysfs-class-led for details.
+config LEDS_HW_CONTROLLED
+ bool "API for LEDs that can be controlled by hardware"
+ depends on LEDS_CLASS
+ select LEDS_TRIGGERS
+ help
+ This option enables support for a generic API via which other drivers
+ can register LEDs that can be put into hardware controlled mode, eg.
+ a LED connected to an ethernet PHY can be configured to blink on
+ network activity.
+
comment "LED drivers"
config LEDS_88PM860X
diff --git a/drivers/leds/Makefile b/drivers/leds/Makefile
index c2c7d7ade0d06..858e468e40df0 100644
--- a/drivers/leds/Makefile
+++ b/drivers/leds/Makefile
@@ -6,6 +6,7 @@ obj-$(CONFIG_LEDS_CLASS) += led-class.o
obj-$(CONFIG_LEDS_CLASS_FLASH) += led-class-flash.o
obj-$(CONFIG_LEDS_CLASS_MULTICOLOR) += led-class-multicolor.o
obj-$(CONFIG_LEDS_TRIGGERS) += led-triggers.o
+obj-$(CONFIG_LEDS_HW_CONTROLLED) += leds-hw-controlled.o
# LED Platform Drivers (keep this sorted, M-| sort)
obj-$(CONFIG_LEDS_88PM860X) += leds-88pm860x.o
diff --git a/drivers/leds/leds-hw-controlled.c b/drivers/leds/leds-hw-controlled.c
new file mode 100644
index 0000000000000..9ef58bf275efd
--- /dev/null
+++ b/drivers/leds/leds-hw-controlled.c
@@ -0,0 +1,227 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Generic API for LEDs that can be controlled by hardware (eg. by an ethernet PHY chip)
+ *
+ * Copyright (C) 2020 Marek Behun <marek.behun@xxxxxx>
+ */
+#include <linux/leds-hw-controlled.h>
+#include <linux/module.h>
+#include <linux/of.h>
+
+int hw_controlled_led_brightness_set(struct led_classdev *cdev, enum led_brightness brightness)
+{
+ struct hw_controlled_led *led = led_cdev_to_hw_controlled_led(cdev);
+ int ret;
+
+ mutex_lock(&led->lock);
+ ret = led->ops->led_brightness_set(cdev->dev->parent, led, brightness);
+ mutex_unlock(&led->lock);
+
+ return ret;
+}
+EXPORT_SYMBOL_GPL(hw_controlled_led_brightness_set);
+
+static int of_register_hw_controlled_led(struct device *dev, struct device_node *np,
+ const char *devicename,
+ const struct hw_controlled_led_ops *ops)
+{
+ struct led_init_data init_data = {};
+ struct hw_controlled_led *led;
+ u32 reg;
+ int ret;
+
+ ret = of_property_read_u32(np, "reg", ®);
+ if (ret < 0)
+ return ret;
+
+ led = devm_kzalloc(dev, sizeof(struct hw_controlled_led), GFP_KERNEL);
+ if (!led)
+ return -ENOMEM;
+
+ led->ops = ops;
+
+ led->cdev.max_brightness = 1;
+ led->cdev.brightness_set_blocking = hw_controlled_led_brightness_set;
+ led->cdev.trigger_type = &hw_control_led_trig_type;
+ led->addr = reg;
+
+ of_property_read_string(np, "linux,default-trigger", &led->cdev.default_trigger);
+ of_property_read_string(np, "linux,default-hw-mode", &led->hw_mode);
+
+ led->active_low = !of_property_read_bool(np, "enable-active-high");
+ led->tristate = of_property_read_bool(np, "led-tristate");
+
+ init_data.fwnode = &np->fwnode;
+ init_data.devname_mandatory = true;
+ init_data.devicename = devicename;
+
+ ret = led->ops->led_init(dev, led);
+ if (ret < 0)
+ goto err_free;
+
+ ret = devm_led_classdev_register_ext(dev, &led->cdev, &init_data);
+ if (ret < 0)
+ goto err_free;
+
+ return 0;
+err_free:
+ devm_kfree(dev, led);
+ return ret;
+}
+
+int of_register_hw_controlled_leds(struct device *dev, const char *devicename,
+ const struct hw_controlled_led_ops *ops)
+{
+ struct device_node *node = dev->of_node;
+ struct device_node *leds, *led;
+ int ret;
+
+ if (!IS_ENABLED(CONFIG_OF_MDIO))
+ return 0;
+
+ if (!ops)
+ return -EINVAL;
+
+ /* maybe we should have of_get_compatible_available_child as well */
+ leds = of_get_compatible_child(node, "linux,hw-controlled-leds");
+ if (!leds)
+ return 0;
+
+ if (!devicename)
+ devicename = dev_name(dev);
+
+ for_each_available_child_of_node(leds, led) {
+ ret = of_register_hw_controlled_led(dev, led, devicename, ops);
+ if (ret < 0)
+ dev_err(dev, "Nonfatal error: cannot register LED from node %pOFn: %i\n",
+ led, ret);
+ }
+
+ return 0;
+}
+EXPORT_SYMBOL_GPL(of_register_hw_controlled_leds);
+
+static int hw_control_led_trig_activate(struct led_classdev *cdev)
+{
+ struct hw_controlled_led *led;
+ int ret;
+
+ led = led_cdev_to_hw_controlled_led(cdev);
+
+ if (!led->hw_mode)
+ return 0;
+
+ mutex_lock(&led->lock);
+ ret = led->ops->led_set_hw_mode(cdev->dev->parent, led, led->hw_mode);
+ mutex_unlock(&led->lock);
+
+ if (ret < 0)
+ dev_warn(cdev->dev->parent, "Could not set HW mode %s on LED %s: %i\n",
+ led->hw_mode, cdev->name, ret);
+
+ /* don't fail to activate this trigger so that user can write hw_mode file */
+ return 0;
+}
+
+static void hw_control_led_trig_deactivate(struct led_classdev *cdev)
+{
+ struct hw_controlled_led *led;
+ int ret;
+
+ led = led_cdev_to_hw_controlled_led(cdev);
+
+ mutex_lock(&led->lock);
+ /* store HW mode before deactivation */
+ led->hw_mode = led->ops->led_get_hw_mode(cdev->dev->parent, led);
+ ret = led->ops->led_set_hw_mode(cdev->dev->parent, led, NULL);
+ mutex_unlock(&led->lock);
+
+ if (ret < 0)
+ dev_err(cdev->dev->parent, "Failed deactivating HW mode on LED %s\n", cdev->name);
+}
+
+static ssize_t hw_mode_show(struct device *dev, struct device_attribute *attr, char *buf)
+{
+ struct hw_controlled_led *led;
+ const char *mode, *cur_mode;
+ void *iter = NULL;
+ int len = 0;
+
+ led = led_cdev_to_hw_controlled_led(led_trigger_get_led(dev));
+
+ mutex_lock(&led->lock);
+
+ cur_mode = led->ops->led_get_hw_mode(dev->parent, led);
+
+ for (mode = led->ops->led_iter_hw_mode(dev->parent, led, &iter);
+ mode;
+ mode = led->ops->led_iter_hw_mode(dev->parent, led, &iter)) {
+ bool sel;
+
+ sel = cur_mode && !strcmp(mode, cur_mode);
+
+ len += scnprintf(buf + len, PAGE_SIZE - len, "%s%s%s ", sel ? "[" : "", mode,
+ sel ? "]" : "");
+ }
+
+ if (buf[len - 1] == ' ')
+ buf[len - 1] = '\n';
+
+ mutex_unlock(&led->lock);
+
+ return len;
+}
+
+static ssize_t hw_mode_store(struct device *dev, struct device_attribute *attr, const char *buf,
+ size_t count)
+{
+ struct hw_controlled_led *led;
+ int ret;
+
+ led = led_cdev_to_hw_controlled_led(led_trigger_get_led(dev));
+
+ mutex_lock(&led->lock);
+ ret = led->ops->led_set_hw_mode(dev->parent, led, buf);
+ if (ret < 0)
+ return ret;
+ mutex_unlock(&led->lock);
+
+ return count;
+}
+
+static DEVICE_ATTR_RW(hw_mode);
+
+static struct attribute *hw_control_led_trig_attrs[] = {
+ &dev_attr_hw_mode.attr,
+ NULL
+};
+ATTRIBUTE_GROUPS(hw_control_led_trig);
+
+struct led_hw_trigger_type hw_control_led_trig_type;
+EXPORT_SYMBOL_GPL(hw_control_led_trig_type);
+
+struct led_trigger hw_control_led_trig = {
+ .name = "dev-hw-mode",
+ .activate = hw_control_led_trig_activate,
+ .deactivate = hw_control_led_trig_deactivate,
+ .trigger_type = &hw_control_led_trig_type,
+ .groups = hw_control_led_trig_groups,
+};
+EXPORT_SYMBOL_GPL(hw_control_led_trig);
+
+static int __init hw_controlled_leds_init(void)
+{
+ return led_trigger_register(&hw_control_led_trig);
+}
+
+static void __exit hw_controlled_leds_exit(void)
+{
+ led_trigger_unregister(&hw_control_led_trig);
+}
+
+subsys_initcall(hw_controlled_leds_init);
+module_exit(hw_controlled_leds_exit);
+
+MODULE_AUTHOR("Marek Behun <marek.behun@xxxxxx>");
+MODULE_LICENSE("GPL v2");
+MODULE_DESCRIPTION("API for HW controlled LEDs");
diff --git a/include/linux/leds-hw-controlled.h b/include/linux/leds-hw-controlled.h
new file mode 100644
index 0000000000000..2c9b8a06def18
--- /dev/null
+++ b/include/linux/leds-hw-controlled.h
@@ -0,0 +1,74 @@
+/* SPDX-License-Identifier: GPL-2.0+ */
+/*
+ * Generic API for LEDs that can be controlled by hardware (eg. by an ethernet PHY chip)
+ *
+ * Copyright (C) 2020 Marek Behun <marek.behun@xxxxxx>
+ */
+#ifndef _LINUX_LEDS_HW_CONTROLLED_H_
+#define _LINUX_LEDS_HW_CONTROLLED_H_
+
+#include <linux/kernel.h>
+#include <linux/leds.h>
+
+struct hw_controlled_led {
+ struct led_classdev cdev;
+ const struct hw_controlled_led_ops *ops;
+ struct mutex lock;
+
+ /* these members are filled in by OF if OF is enabled */
+ int addr;
+ bool active_low;
+ bool tristate;
+
+ /* also filled in by OF, but changed by led_set_hw_mode operation */
+ const char *hw_mode;
+
+ void *priv;
+};
+#define led_cdev_to_hw_controlled_led(l) container_of(l, struct hw_controlled_led, cdev)
+
+/* struct hw_controlled_led_ops: Operations on LEDs that can be controlled by HW
+ *
+ * All the following operations must be implemented:
+ * @led_init: Should initialize the LED from OF data (and sanity check whether they are correct).
+ * This should also change led->cdev.max_brightness, if the value differs from default,
+ * which is 1.
+ * @led_brightness_set: Sets brightness.
+ * @led_iter_hw_mode: Iterates available HW control mode names for this LED.
+ * @led_set_hw_mode: Sets HW control mode to value specified by given name.
+ * @led_get_hw_mode: Returns current HW control mode name.
+ */
+struct hw_controlled_led_ops {
+ int (*led_init)(struct device *dev, struct hw_controlled_led *led);
+ int (*led_brightness_set)(struct device *dev, struct hw_controlled_led *led,
+ enum led_brightness brightness);
+ const char *(*led_iter_hw_mode)(struct device *dev, struct hw_controlled_led *led,
+ void **iter);
+ int (*led_set_hw_mode)(struct device *dev, struct hw_controlled_led *led,
+ const char *mode);
+ const char *(*led_get_hw_mode)(struct device *dev, struct hw_controlled_led *led);
+};
+
+#if IS_ENABLED(CONFIG_LEDS_HW_CONTROLLED)
+
+#define hw_controlled_led_ops_ptr(s) (s)
+
+int of_register_hw_controlled_leds(struct device *dev, const char *devicename,
+ const struct hw_controlled_led_ops *ops);
+int hw_controlled_led_brightness_set(struct led_classdev *cdev, enum led_brightness brightness);
+
+extern struct led_hw_trigger_type hw_control_led_trig_type;
+extern struct led_trigger hw_control_led_trig;
+
+#else /* !IS_ENABLED(CONFIG_LEDS_HW_CONTROLLED) */
+
+#define hw_controlled_led_ops_ptr(s) NULL
+static inline int of_register_hw_controlled_leds(struct device *dev, const char *devicename,
+ const struct hw_controlled_led_ops *ops)
+{
+ return 0;
+}
+
+#endif /* !IS_ENABLED(CONFIG_LEDS_HW_CONTROLLED) */
+
+#endif /* _LINUX_LEDS_HW_CONTROLLED_H_ */
--
2.26.2
