include/bsp/i2c.h

0001 /**
0002  * @file
0003  *
0004  * @ingroup raspberrypi_i2c
0005  *
0006  * @brief Raspberry Pi specific I2C definitions.
0007  */
0008
0009 /*
0010  *  Copyright (c) 2014-2015 Andre Marques <andre.lousa.marques at gmail.com>
0011  *
0012  *  The license and distribution terms for this file may be
0013  *  found in the file LICENSE in this distribution or at
0014  *  http://www.rtems.org/license/LICENSE.
0015  */
0016
0017 #ifndef LIBBSP_ARM_RASPBERRYPI_I2C_H
0018 #define LIBBSP_ARM_RASPBERRYPI_I2C_H
0019
0020 #include <dev/i2c/i2c.h>
0021
0022 #ifdef __cplusplus
0023 extern "C" {
0024 #endif /* __cplusplus */
0025
0026 /**
0027  * @name I2C constants.
0028  *
0029  * @{
0030  */
0031
0032 /**
0033  * @brief BSC controller core clock rate in Hz.
0034  *
0035  * This is set to 150 MHz as per the BCM2835 datasheet.
0036  */
0037 #define BSC_CORE_CLK_HZ 150000000
0038
0039 /**
0040  * @brief Default bus clock.
0041  *
0042  * This sets the bus with a 100 kHz clock speed.
0043  */
0044 #define DEFAULT_BUS_CLOCK 100000
0045
0046 /** @} */
0047
0048 /**
0049  * @name  I2C directives.
0050  *
0051  * @{
0052  */
0053
0054 /**
0055  * @brief Setups the Raspberry Pi GPIO header to activate the BSC I2C bus.
0056  */
0057 extern void rpi_i2c_init(void);
0058
0059 /**
0060  * @brief Registers the Raspberry Pi BSC I2C bus with the
0061  *        Linux I2C User-Space API.
0062  *
0063  * @param[in] bus_path Path to the bus device file.
0064  * @param[in] bus_clock Bus clock in Hz.
0065  *
0066  * @retval 0 Bus registered successfully.
0067  * @retval <0 Could not register the bus. The return value is a negative
0068  *            errno code.
0069  */
0070 extern int rpi_i2c_register_bus(
0071   const char *bus_path,
0072   uint32_t bus_clock
0073 );
0074
0075 /**
0076  * @brief Setups the Raspberry Pi BSC I2C bus (located on the GPIO header)
0077  *        on the "/dev/i2c" device file, using the default bus clock.
0078  *
0079  * @retval 0 Bus configured and registered successfully.
0080  * @retval <0 See @see rpi_i2c_register_bus().
0081  */
0082 static inline int rpi_setup_i2c_bus(void)
0083 {
0084   rpi_i2c_init();
0085
0086   return rpi_i2c_register_bus("/dev/i2c", DEFAULT_BUS_CLOCK);
0087 }
0088
0089 /** @} */
0090
0091 #ifdef __cplusplus
0092 }
0093 #endif /* __cplusplus */
0094
0095 #endif /* LIBBSP_ARM_RASPBERRYPI_I2C_H */