leds: Add LED Flash class extension to the LED subsystem

Some LED devices support two operation modes - torch and flash.
This patch provides support for flash LED devices in the LED subsystem
by introducing new sysfs attributes and kernel internal interface.
The attributes being introduced are: flash_brightness, flash_strobe,
flash_timeout, max_flash_timeout, max_flash_brightness, flash_fault,
flash_sync_strobe and available_sync_leds. All the flash related
features are placed in a separate module.

The modifications aim to be compatible with V4L2 framework requirements
related to the flash devices management. The design assumes that V4L2
sub-device can take of the LED class device control and communicate
with it through the kernel internal interface. When V4L2 Flash sub-device
file is opened, the LED class device sysfs interface is made
unavailable.

Signed-off-by: Jacek Anaszewski <j.anaszewski@samsung.com>
Acked-by: Kyungmin Park <kyungmin.park@samsung.com>
Cc: Richard Purdie <rpurdie@rpsys.net>
Acked-by: Pavel Machek <pavel@ucw.cz>
Signed-off-by: Bryan Wu <cooloney@gmail.com>

1 files changed, 207 insertions, 0 deletions

diff --git a/include/linux/led-class-flash.h b/include/linux/led-class-flash.h
new file mode 100644
index 000000000000..5ba2facd7a51
--- /dev/null
+++ b/include/linux/led-class-flash.h
@@ -0,0 +1,207 @@
+/*
+ * LED Flash class interface
+ *
+ * Copyright (C) 2015 Samsung Electronics Co., Ltd.
+ * Author: Jacek Anaszewski <j.anaszewski@samsung.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ */
+#ifndef __LINUX_FLASH_LEDS_H_INCLUDED
+#define __LINUX_FLASH_LEDS_H_INCLUDED
+
+#include <linux/leds.h>
+#include <uapi/linux/v4l2-controls.h>
+
+struct device_node;
+struct led_classdev_flash;
+
+/*
+ * Supported led fault bits - must be kept in synch
+ * with V4L2_FLASH_FAULT bits.
+ */
+#define LED_FAULT_OVER_VOLTAGE          (1 << 0)
+#define LED_FAULT_TIMEOUT               (1 << 1)
+#define LED_FAULT_OVER_TEMPERATURE      (1 << 2)
+#define LED_FAULT_SHORT_CIRCUIT         (1 << 3)
+#define LED_FAULT_OVER_CURRENT          (1 << 4)
+#define LED_FAULT_INDICATOR             (1 << 5)
+#define LED_FAULT_UNDER_VOLTAGE         (1 << 6)
+#define LED_FAULT_INPUT_VOLTAGE         (1 << 7)
+#define LED_FAULT_LED_OVER_TEMPERATURE  (1 << 8)
+#define LED_NUM_FLASH_FAULTS            9
+
+#define LED_FLASH_MAX_SYSFS_GROUPS 7
+
+struct led_flash_ops {
+        /* set flash brightness */
+        int (*flash_brightness_set)(struct led_classdev_flash *fled_cdev,
+                                        u32 brightness);
+        /* get flash brightness */
+        int (*flash_brightness_get)(struct led_classdev_flash *fled_cdev,
+                                        u32 *brightness);
+        /* set flash strobe state */
+        int (*strobe_set)(struct led_classdev_flash *fled_cdev, bool state);
+        /* get flash strobe state */
+        int (*strobe_get)(struct led_classdev_flash *fled_cdev, bool *state);
+        /* set flash timeout */
+        int (*timeout_set)(struct led_classdev_flash *fled_cdev, u32 timeout);
+        /* get the flash LED fault */
+        int (*fault_get)(struct led_classdev_flash *fled_cdev, u32 *fault);
+};
+
+/*
+ * Current value of a flash setting along
+ * with its constraints.
+ */
+struct led_flash_setting {
+        /* maximum allowed value */
+        u32 min;
+        /* maximum allowed value */
+        u32 max;
+        /* step value */
+        u32 step;
+        /* current value */
+        u32 val;
+};
+
+struct led_classdev_flash {
+        /* led class device */
+        struct led_classdev led_cdev;
+
+        /* flash led specific ops */
+        const struct led_flash_ops *ops;
+
+        /* flash brightness value in microamperes along with its constraints */
+        struct led_flash_setting brightness;
+
+        /* flash timeout value in microseconds along with its constraints */
+        struct led_flash_setting timeout;
+
+        /* LED Flash class sysfs groups */
+        const struct attribute_group *sysfs_groups[LED_FLASH_MAX_SYSFS_GROUPS];
+
+        /* LEDs available for flash strobe synchronization */
+        struct led_classdev_flash **sync_leds;
+
+        /* Number of LEDs available for flash strobe synchronization */
+        int num_sync_leds;
+
+        /*
+         * The identifier of the sub-led to synchronize the flash strobe with.
+         * Identifiers start from 1, which reflects the first element from the
+         * sync_leds array. 0 means that the flash strobe should not be
+         * synchronized.
+         */
+        u32 sync_led_id;
+};
+
+static inline struct led_classdev_flash *lcdev_to_flcdev(
+                                                struct led_classdev *lcdev)
+{
+        return container_of(lcdev, struct led_classdev_flash, led_cdev);
+}
+
+/**
+ * led_classdev_flash_register - register a new object of led_classdev class
+ *                               with support for flash LEDs
+ * @parent: the flash LED to register
+ * @fled_cdev: the led_classdev_flash structure for this device
+ *
+ * Returns: 0 on success or negative error value on failure
+ */
+extern int led_classdev_flash_register(struct device *parent,
+                                struct led_classdev_flash *fled_cdev);
+
+/**
+ * led_classdev_flash_unregister - unregisters an object of led_classdev class
+ *                                 with support for flash LEDs
+ * @fled_cdev: the flash LED to unregister
+ *
+ * Unregister a previously registered via led_classdev_flash_register object
+ */
+extern void led_classdev_flash_unregister(struct led_classdev_flash *fled_cdev);
+
+/**
+ * led_set_flash_strobe - setup flash strobe
+ * @fled_cdev: the flash LED to set strobe on
+ * @state: 1 - strobe flash, 0 - stop flash strobe
+ *
+ * Strobe the flash LED.
+ *
+ * Returns: 0 on success or negative error value on failure
+ */
+static inline int led_set_flash_strobe(struct led_classdev_flash *fled_cdev,
+                                        bool state)
+{
+        return fled_cdev->ops->strobe_set(fled_cdev, state);
+}
+
+/**
+ * led_get_flash_strobe - get flash strobe status
+ * @fled_cdev: the flash LED to query
+ * @state: 1 - flash is strobing, 0 - flash is off
+ *
+ * Check whether the flash is strobing at the moment.
+ *
+ * Returns: 0 on success or negative error value on failure
+ */
+static inline int led_get_flash_strobe(struct led_classdev_flash *fled_cdev,
+                                        bool *state)
+{
+        if (fled_cdev->ops->strobe_get)
+                return fled_cdev->ops->strobe_get(fled_cdev, state);
+
+        return -EINVAL;
+}
+
+/**
+ * led_set_flash_brightness - set flash LED brightness
+ * @fled_cdev: the flash LED to set
+ * @brightness: the brightness to set it to
+ *
+ * Set a flash LED's brightness.
+ *
+ * Returns: 0 on success or negative error value on failure
+ */
+extern int led_set_flash_brightness(struct led_classdev_flash *fled_cdev,
+                                        u32 brightness);
+
+/**
+ * led_update_flash_brightness - update flash LED brightness
+ * @fled_cdev: the flash LED to query
+ *
+ * Get a flash LED's current brightness and update led_flash->brightness
+ * member with the obtained value.
+ *
+ * Returns: 0 on success or negative error value on failure
+ */
+extern int led_update_flash_brightness(struct led_classdev_flash *fled_cdev);
+
+/**
+ * led_set_flash_timeout - set flash LED timeout
+ * @fled_cdev: the flash LED to set
+ * @timeout: the flash timeout to set it to
+ *
+ * Set the flash strobe duration.
+ *
+ * Returns: 0 on success or negative error value on failure
+ */
+extern int led_set_flash_timeout(struct led_classdev_flash *fled_cdev,
+                                        u32 timeout);
+
+/**
+ * led_get_flash_fault - get the flash LED fault
+ * @fled_cdev: the flash LED to query
+ * @fault: bitmask containing flash faults
+ *
+ * Get the flash LED fault.
+ *
+ * Returns: 0 on success or negative error value on failure
+ */
+extern int led_get_flash_fault(struct led_classdev_flash *fled_cdev,
+                                        u32 *fault);
+
+#endif  /* __LINUX_FLASH_LEDS_H_INCLUDED */