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| Source | Mainlined? |
|---|---|
| git | In Progress |
| Function | File |
|---|---|
| driver | drivers/leds/leds-adp1650.c |
| include | include/linux/i2c/adp1650.h |
For compile time configuration, it’s common Linux practice to keep board- and application-specific configuration out of the main driver file, instead putting it into the board support file.
For devices on custom boards, as typical of embedded and SoC-(system-on-chip) based hardware, Linux uses platform_data to point to board-specific structures describing devices and how they are connected to the SoC. This can include available ports, chip variants, preferred modes, default initialization, additional pin roles, and so on. This shrinks the board-support packages (BSPs) and minimizes board and application specific #ifdefs in drivers.
platform_data: Platform data specific to the ADP1650 device.
Includes feature selections and default initialization.
Please see include/linux/i2c/adp1650.h for details.
#includestatic struct adp1650_leds_platform_data adp1650_pdata = { .timer_iocfg = ADP1650_IOCFG_IO2_HIGH_IMP | ADP1650_IOCFG_IO1_TORCH | ADP1650_FL_TIMER_ms(500), .current_set = ADP1650_I_FL_mA(900) | ADP1650_I_TOR_mA(100), .output_mode = ADP1650_IL_PEAK_2A25 | ADP1650_STR_LV_EDGE | ADP1650_FREQ_FB_EN | ADP1650_OUTPUT_EN | ADP1650_STR_MODE_HW | ADP1650_STR_MODE_STBY, .control = ADP1650_I_TX2_mA(400) | ADP1650_I_TX1_mA(400), .ad_mode = ADP1650_DYN_OVP_EN | ADP1650_STR_POL_ACTIVE_HIGH | ADP1650_I_ILED_2mA75 | ADP1650_IL_DC_1A50 | ADP1650_IL_DC_EN, .batt_low = ADP1650_CL_SOFT_EN | ADP1650_I_VB_LO_mA(400) | ADP1650_V_VB_LO_3V50, .gpio_enable = -1, };
Unlike PCI or USB devices, I2C devices are not enumerated at the hardware level. Instead, the software must know which devices are connected on each I2C bus segment, and what address these devices are using. For this reason, the kernel code must instantiate I2C devices explicitly. There are different ways to achieve this, depending on the context and requirements. However the most common method is to declare the I2C devices by bus number.
This method is appropriate when the I2C bus is a system bus, as in many embedded systems, wherein each I2C bus has a number which is known in advance. It is thus possible to pre-declare the I2C devices that inhabit this bus. This is done with an array of struct i2c_board_info, which is registered by calling i2c_register_board_info().
So, to enable such a driver one need only edit the board support file by adding an appropriate entry to i2c_board_info.
For more information see: Documentation/i2c/instantiating-devices
static struct i2c_board_info __initdata board_i2c_board_info[] = { #if defined(CONFIG_LEDS_ADP1650) || defined(CONFIG_LEDS_ADP1650_MODULE) { I2C_BOARD_INFO("adp1650", 0x30), .platform_data = (void *)&adp1650_pdata, }, #endif };
static int __init board_init(void) { [--snip--] i2c_register_board_info(0, board_i2c_board_info, ARRAY_SIZE(board_i2c_board_info)); [--snip--] return 0; } arch_initcall(board_init);
Configure kernel with “make menuconfig” (alternatively use “make xconfig” or “make qconfig”)
The ADP1650 LED driver depends on I2C.
Device Drivers ---> [*] LED Support ---> --- LED Support [*] LED Class Support * LED drivers * <--snip--> <*> LED Support for ADP1650 I2C chips <--snip-->
The LED class allows control of LEDs from userspace. LEDs appear in /sys/class/leds/. The brightness file will set the brightness of the LED (taking a value 0-255).
For more information read linux/Documentaion/leds-class.txt
| Value | Define | Description | Intensity |
|---|---|---|---|
| 0 | FL_MODE_OFF | Turns LED/FLASH off | 0 |
| 1 | FL_MODE_TORCH_25mA | Software initiated TORCH/Assist light | 25mA |
| 2 | FL_MODE_TORCH_50mA | (STROBE) triggers FLASH | 50mA |
| 3 | FL_MODE_TORCH_75mA | 75mA | |
| 4 | FL_MODE_TORCH_100mA | 100mA | |
| 5 | FL_MODE_TORCH_125mA | 125mA | |
| 6 | FL_MODE_TORCH_150mA | 150mA | |
| 7 | FL_MODE_TORCH_175mA | 175mA | |
| 8 | FL_MODE_TORCH_200mA | 200mA | |
| 9 | FL_MODE_TORCH_TRIG_EXT_25mA | Hardware (GPIO1) triggered TORCH/Assist light | 25mA |
| 10 | FL_MODE_TORCH_TRIG_EXT_50mA | (STROBE) triggers FLASH | 50mA |
| 11 | FL_MODE_TORCH_TRIG_EXT_75mA | 75mA | |
| 12 | FL_MODE_TORCH_TRIG_EXT_100mA | 100mA | |
| 13 | FL_MODE_TORCH_TRIG_EXT_125mA | 125mA | |
| 14 | FL_MODE_TORCH_TRIG_EXT_150mA | 150mA | |
| 15 | FL_MODE_TORCH_TRIG_EXT_175mA | 175mA | |
| 16 | FL_MODE_TORCH_TRIG_EXT_200mA | 200mA | |
| 254 | FL_MODE_FLASH | Software initiated LED FLASH | I_FL |
| 255 | FL_MODE_FLASH_TRIG_EXT | Hardware (STROBE) triggered LED FLASH | I_FL |
root:/> cd sys/class/leds/adp1650/ root:/sys/devices/platform/i2c-bfin-twi.0/i2c-0/0-0030/leds/adp1650> ls -l -rw-r--r-- 1 root root 4096 Jan 5 08:42 brightness lrwxrwxrwx 1 root root 0 Jan 5 08:23 device -> ../../../0-0030 -r--r--r-- 1 root root 4096 Jan 5 08:23 max_brightness drwxr-xr-x 2 root root 0 Jan 5 08:23 power lrwxrwxrwx 1 root root 0 Jan 5 08:23 subsystem -> ../../../../../../../class/leds -rw-r--r-- 1 root root 4096 Jan 5 08:23 uevent
A subsequent assert of STROBE will trigger the FLASH
This specifies any shell prompt running on the target
root:/sys/devices/platform/i2c-bfin-twi.0/i2c-0/0-0030/leds/adp1650> echo 4 > brightness
A subsequent assert of STROBE will trigger the FLASH
This specifies any shell prompt running on the target
root:/sys/devices/platform/i2c-bfin-twi.0/i2c-0/0-0030/leds/adp1650> echo 12 > brightness
This specifies any shell prompt running on the target
root:/sys/devices/platform/i2c-bfin-twi.0/i2c-0/0-0030/leds/adp1650> echo 254 > brightness
This specifies any shell prompt running on the target
root:/sys/devices/platform/i2c-bfin-twi.0/i2c-0/0-0030/leds/adp1650> echo 255 > brightness
This specifies any shell prompt running on the target
root:/sys/devices/platform/i2c-bfin-twi.0/i2c-0/0-0030/leds/adp1650> echo 0 > brightness
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