The ADP5520/01 driver utilizes several Linux device-driver subsystems and provides various software interfaces. It is therefore implemented as a multifunction device (MFD). In this particular case the ADP5520 backlight driver and I/O expander, concurrently leverages the Linux backlight, LED, GPIO, and input subsystems for its keypad functionality.
The ADP5520/01 core driver in drivers/mfd provides common services for the subsystem drivers. These services include register access, control and shared interrupt management.
The core registers/enumerates platform devices for the various subsystems via the platform device and driver system.
When a platform driver for one of the subsystems is instantiated, the core initializes the chip (which may be specified by the platform data).
The ADP5520/01 platform drivers follow the standard driver model convention, where discovery/enumeration is handled outside the drivers, and drivers provide probe() and remove() methods.
Each peripheral (subsystem device) has a view of the device which is implicitly narrowed to the specific set of resources that peripheral requires in order to function correctly.
The device driver uses a set of platform data to pass configurations through to the core and the subsidiary drivers so that there can be support for multiple ADP5520/01 devices built into a single kernel image.
Backlight:
LED:
Keypad:
GPIO:
Function | File |
---|---|
MFD-CORE | drivers/mfd/adp5520.c |
include | include/linux/mfd/adp5520.h |
BACKLIGHT | drivers/video/backlight/adp5520_bl.c |
LED | drivers/led/leds-adp5520.c |
GPIO | drivers/gpio/adp5520-gpio.c1) |
KEYPAD | drivers/input/keyboard/adp5520-keys.c2) |
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.
Since Keypad, GPIO and optional LEDs (2, 3) are multiplexed, you need to avoid double configurations. Please refer to the table below.
ADP5520 PIN | R3 | R2 | R1 | R0 | C0 | C1 | C2 | C3 |
---|---|---|---|---|---|---|---|---|
GPIO | GPIO_R3 | GPIO_R2 | GPIO_R1 | GPIO_R0 | GPIO_C0 | GPIO_C1 | GPIO_C2 | GPIO_C3 |
Keypad | ROW_R3 | ROW_R2 | ROW_R1 | ROW_R0 | COL_C0 | COL_C1 | COL_C2 | COL_C3 |
LED | LED3 | LED2 |
Please refer to include/linux/mfd/adp5520.h for detailed configuration defines.
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
ADP5520 IRQ Usage:
If you aren’t planning to utilize the Keypad interface, you don’t need to specify an IRQ in bfin_i2c_board_info.
Fist of all you need to enable i2c support followed by the ADP5520 MFD Core Driver. Then you may select individual components like LCD backlight, LEDs, GPIOs and Keypad under the corresponding menus.
Device Drivers ---> <*> I2C support ---> <*> Blackfin TWI I2C support Or: <*> GPIO-based bitbanging I2C Device Drivers ---> Multifunction device drivers ---> [*] Analog Devices ADP5520/01 MFD PMIC Core Support
Device Drivers ---> Graphics support ---> [*] Backlight & LCD device support ---> <*> Lowlevel Backlight controlsBacklight Driver for ADP5520/ADP5501 using WLED
Device Drivers ---> [*] LED Support ---> <*> LED Class SupportLED Support for ADP5520/ADP5501 PMIC
Device Drivers ---> [*] GPIO Support ---> [*] /sys/class/gpio/... (sysfs interface)GPIO Support for ADP5520 PMIC
Device Drivers ---> Input device support ---> <*> Generic input layer (needed for keyboard, mouse, ...) <*> Event interface [*] Keyboards --->Keypad Support for ADP5520 PMIC
There is no dedicated Blackfin STAMP evaluation board for the ADP5520. During test and driver development we used the ADP5520 Demo Mother/Daughter Board. Connect the ADP5520 Demo Mother to an USB port.
It can be easily wired to the Blackfin STAMP TWI/I2C header.
BF537-STAMP (P10) TWI/I2C header | ADP5520 Daughter Board | |
---|---|---|
PIN | Function | PIN/Function |
5 | SCL | SCL |
6 | SDA | SDA |
10 | GPIO_PG0 | nINT |
20 | GND | GND |
root:/> modprobe adp5520_bl root:/> root:/> cd sys/class/backlight/adp5520-backlight/ root:/sys/devices/platform/i2c-bfin-twi.0/i2c-adapter/i2c-0/0-0032/backlight/adp5520-backlight> ls -l -r--r--r-- 1 root root 4096 Nov 12 10:31 actual_brightness -rw-r--r-- 1 root root 4096 Nov 12 10:31 bl_power -rw-r--r-- 1 root root 4096 Nov 12 10:31 brightness -rw-rw-r-- 1 root root 4096 Nov 12 10:31 dark_dim -rw-rw-r-- 1 root root 4096 Nov 12 10:31 dark_max -rw-rw-r-- 1 root root 4096 Nov 12 10:31 daylight_dim -rw-rw-r-- 1 root root 4096 Nov 12 10:31 daylight_max lrwxrwxrwx 1 root root 0 Nov 12 10:31 device -> ../../../0-0032 -r--r--r-- 1 root root 4096 Nov 12 10:31 max_brightness -rw-rw-r-- 1 root root 4096 Nov 12 10:31 office_dim -rw-rw-r-- 1 root root 4096 Nov 12 10:31 office_max drwxr-xr-x 2 root root 0 Nov 12 10:31 power lrwxrwxrwx 1 root root 0 Nov 12 10:31 subsystem -> ../../../../../../../../class/backlight root:/sys/devices/platform/i2c-bfin-twi.0/i2c-adapter/i2c-0/0-0032/backlight/adp5520-backlight> echo 127 > brightness root:/sys/devices/platform/i2c-bfin-twi.0/i2c-adapter/i2c-0/0-0032/backlight/adp5520-backlight> echo 50 > brightness root:/sys/devices/platform/i2c-bfin-twi.0/i2c-adapter/i2c-0/0-0032/backlight/adp5520-backlight> echo 0 > brightness
For more information on Backlight handling in Linux read: Documentation/ABI/stable/sysfs-class-backlight
root:/> modprobe leds-adp5520 Registered led device: adp5520-led1 Registered led device: adp5520-led2 Registered led device: adp5520-led3 root:/> cd sys/class/leds/adp5520-led sys/class/leds/adp5520-led1/ sys/class/leds/adp5520-led3/ sys/class/leds/adp5520-led2/ root:/> cd sys/class/leds/adp5520-led1 root:/sys/devices/platform/i2c-bfin-twi.0/i2c-adapter/i2c-0/0-0032/leds/adp5520-led1> ls -l -rw-r--r-- 1 root root 4096 Nov 12 10:34 brightness lrwxrwxrwx 1 root root 0 Nov 12 10:34 device -> ../../../0-0032 drwxr-xr-x 2 root root 0 Nov 12 10:34 power lrwxrwxrwx 1 root root 0 Nov 12 10:34 subsystem -> ../../../../../../../../class/leds -rw-r--r-- 1 root root 4096 Nov 12 10:34 trigger root:/sys/devices/platform/i2c-bfin-twi.0/i2c-adapter/i2c-0/0-0032/leds/adp5520-led1> echo 10 > brightness root:/sys/devices/platform/i2c-bfin-twi.0/i2c-adapter/i2c-0/0-0032/leds/adp5520-led1> echo 255 > brightness root:/sys/devices/platform/i2c-bfin-twi.0/i2c-adapter/i2c-0/0-0032/leds/adp5520-led1> echo 0 > brightness root:/> modprobe -r leds-adp5520 root:/>
For more information on LEDs handling in Linux read: Documentation/leds-class.txt
root:/> modprobe adp5520-gpio root:/> cd sys/class/gpio/gpiochip50/ root:/sys/devices/virtual/gpio/gpiochip50> ls -l -r--r--r-- 1 root root 4096 Nov 12 10:37 base -r--r--r-- 1 root root 4096 Nov 12 10:37 label -r--r--r-- 1 root root 4096 Nov 12 10:37 ngpio drwxr-xr-x 2 root root 0 Nov 12 10:37 power lrwxrwxrwx 1 root root 0 Nov 12 10:37 subsystem -> ../../../../class/gpio -rw-r--r-- 1 root root 4096 Nov 12 10:37 uevent root:/sys/devices/virtual/gpio/gpiochip50> cd root:/>Note that you will have to enable the event_test utility under “Blackfin test programs” in your user space configuration.
--- Blackfin test programs [*] Input event device test
For more information on GPIO handling in Linux read: Documentation/gpio.txt
root:/> modprobe adp5520-keys input: adp5520-keys as /devices/platform/i2c-bfin-twi.0/i2c-adapter/i2c-0/0-0032/adp5520-keys.5520/input/input0 root:/> event_test /dev/input/event0 Input driver version is 1.0.0 Input device ID: bus 0x18 vendor 0x1 product 0x5520 version 0x1 Input device name: "adp5520-keys" Supported events: Event type 0 (Reset) Event code 0 (Reset) Event code 1 (Key) Event type 1 (Key) Event code 2 (1) Event code 3 (2) Event code 4 (3) Event code 5 (4) Event code 6 (5) Event code 7 (6) Event code 8 (7) Event code 9 (8) Event code 10 (9) Event code 11 (0) Event code 12 (Minus) Event code 13 (Equal) Event code 28 (Enter) Event code 41 (Grave) Event code 43 (BackSlash) Testing ... (interrupt to exit) Event: time 1415788674.340000, type 1 (Key), code 41 (Grave), value 1 Event: time 1415788674.340000, type 0 (Reset), code 0 (Reset), value 0 Event: time 1415788674.516000, type 1 (Key), code 41 (Grave), value 0 Event: time 1415788674.516000, type 0 (Reset), code 0 (Reset), value 0 Event: time 1415788674.912000, type 1 (Key), code 2 (1), value 1 Event: time 1415788674.912000, type 0 (Reset), code 0 (Reset), value 0 Event: time 1415788675.140000, type 1 (Key), code 2 (1), value 0 Event: time 1415788675.140000, type 0 (Reset), code 0 (Reset), value 0 Event: time 1415788675.892000, type 1 (Key), code 6 (5), value 1 Event: time 1415788675.892000, type 0 (Reset), code 0 (Reset), value 0 Event: time 1415788676.092000, type 1 (Key), code 6 (5), value 0 Event: time 1415788676.092000, type 0 (Reset), code 0 (Reset), value 0 root:/> modprobe -r adp5520-keys root:/>
For more information on Input handling in Linux read: Documentation/input/input.txt
声明:本文内容及配图由入驻作者撰写或者入驻合作网站授权转载。文章观点仅代表作者本人,不代表电子发烧友网立场。文章及其配图仅供工程师学习之用,如有内容侵权或者其他违规问题,请联系本站处理。 举报投诉
全部0条评论
快来发表一下你的评论吧 !