The forums are retiring and are now closed for new topics and comments. The existing content will remain online and accessible through 2020 to provide everyone the opportunity to save any relevant information. In the spring of 2021, these Community forums will be taken offline.

Search for Raspbian Wheezy in Topics

Can maynard shell work with raspbian wheezy or is it a different OS?

From what I understand it will be a OS, or will it be a add-on for other operating systems?

Question by nerd7473    |  last reply

Char Device Driver with Port Expansion using MCP23017?

I am new to Linux Kernel Development and I want to implement a Char device driver which handles Port expansion using a MCP23017 with a RaspberryPi (Raspbian Wheezy) using C. Here is the datesheet of mcp23017 A control for port expansion (MCP23017) is required. A less of a driver in the true sense, but more with porting functions in a driver.   The module is addressed via I2C. I need to implement the following functions in the driver: · Configuration of the I2C address · Configuration of the IOs · Configuration of Pull-Ups · Configuration of interrupts · Read / write the IOs It is important that up to 8 modules can be opened/operated simultaneously (8 is the max. possible number of addresses of the block). I have seen a number of examples in the internet and implemented a simple char device driver with init, open, read and write functions and also tested I2C operations for MCP23017. I have got a brief idea about a device driver but don't know how to further implement the functions. I would like to know/clarified about the following:     How does the dev_open work? How can I try to open a device through a linux command and check if the device is opened/ the number of times the device is opened through dmesg command?     I want 8 different modules to be opened simultaneously using the device driver and the Configuration of the MCP23017 IOs, Pullups and Interrupts. How is it done? Errors: /home/pi/i2c_gpio/mcp23017.c: In function ‘mcp23s08_direction_input’: /home/pi/i2c_gpio/mcp23017.c:269:9: error: implicit declaration of function      ‘gpiochip_get_data’ [-Werror=implicit-function-declaration] struct mcp23s08 *mcp = gpiochip_get_data(chip);      /home/pi/i2c_gpio/mcp23017.c: In function ‘mcp23s08_probe_one’: /home/pi/i2c_gpio/mcp23017.c:615:11: error: ‘struct gpio_chip’ has no         member  named ‘parent’ mcp->chip.parent = dev;                  /home/pi/i2c_gpio/mcp23017.c:681:2: error: implicit declaration of  function ‘gpiochip_add_data’ [-Werror=implicit-function-declaration] status = gpiochip_add_data(&mcp-;>chip, mcp); ^

Question by DELETED_MakiY2    |  last reply