/** * @file can.c * * @ingroup lpc176x * * @brief CAN controller for the mbed lpc1768 board. */ /* * Copyright (c) 2014 Taller Technologies. * * @author Diaz Marcos (marcos.diaz@tallertechnologies.com) * @author Daniel Chicco (daniel.chicco@tallertechnologies.com) * * The license and distribution terms for this file may be * found in the file LICENSE in this distribution or at * http://www.rtems.org/license/LICENSE. */ #include #include #include #include #include #include /** * @brief The standard isr to be installed for all the can devices. * * @param arg unused. */ static void can_isr( void *arg ); /** * @brief Vector of isr for the can_driver . */ lpc176x_can_isr_vector isr_vector; /** * @brief Represents all the can devices, and useful things for initialization. */ static const can_driver_entry can_driver_table[ CAN_DEVICES_NUMBER ] = { { .device = (can_device *) CAN1_BASE_ADDR, .module = LPC176X_MODULE_CAN_0, .pconp_pin = LPC176X_SCB_PCONP_CAN_1, .pins = { DIP9, DIP10 }, .pinfunction = LPC176X_PIN_FUNCTION_01 }, { .device = (can_device *) CAN2_BASE_ADDR, .module = LPC176X_MODULE_CAN_1, .pconp_pin = LPC176X_SCB_PCONP_CAN_2, .pins = { DIP30, DIP29 }, .pinfunction = LPC176X_PIN_FUNCTION_10 } }; /** * @brief The CAN acceptance filter. */ can_acceptance_filter *const acceptance_filter_device = (can_acceptance_filter *) CAN_ACCEPT_BASE_ADDR; /** * @brief Sets RX and TX pins for the passed can device number. * * @param cannumber CAN controller to be used. */ static inline void setpins( const lpc176x_can_number cannumber ) { const can_driver_entry *const can_driver = &can_driver_table[ cannumber ]; lpc176x_pin_select( can_driver->pins[ CAN_TX_PIN ], can_driver->pinfunction ); lpc176x_pin_select( can_driver->pins[ CAN_RX_PIN ], can_driver->pinfunction ); } rtems_status_code can_close( const lpc176x_can_number minor ) { rtems_status_code sc = RTEMS_INVALID_NUMBER; if ( CAN_DRIVER_IS_MINOR_VALID( minor ) ) { sc = RTEMS_SUCCESSFUL; const can_driver_entry *const can_driver = &can_driver_table[ minor ]; lpc176x_module_disable( can_driver->module ); } /*else wrong parameters. return RTEMS_INVALID_NUMBER*/ return sc; } /** * @brief Enables CAN device. * * @param obj The device to be enabled. */ static inline void can_enable( const can_driver_entry *const obj ) { if ( obj->device->MOD & CAN_MOD_RM ) { obj->device->MOD &= ~( CAN_MOD_RM ); } } /** * @brief Disables CAN device to set parameters, and returns the previous value * of the MOD register. * * @param obj The device to disable. * @return The previous status of MOD register. */ static inline uint32_t can_disable( const can_driver_entry *const obj ) { const uint32_t sm = obj->device->MOD; obj->device->MOD |= CAN_MOD_RM; return sm; } /** * @brief Resets the error count. * * @param obj which device reset. */ static inline void can_reset( const can_driver_entry *const obj ) { can_disable( obj ); obj->device->GSR = 0; /* Reset error counter when CANxMOD is in reset*/ } /** * @brief This table has the sampling points as close to 75% as possible. * The first value is TSEG1, the second is TSEG2. */ static const unsigned int timing_pts[ MAX_TSEG1_TSEG2_BITS + 1 ][ CAN_NUMBER_OF_TSEG ] = { { 0x0, 0x0 }, /* 2, 50%*/ { 0x1, 0x0 }, /* 3, 67%*/ { 0x2, 0x0 }, /* 4, 75%*/ { 0x3, 0x0 }, /* 5, 80%*/ { 0x3, 0x1 }, /* 6, 67%*/ { 0x4, 0x1 }, /* 7, 71%*/ { 0x5, 0x1 }, /* 8, 75%*/ { 0x6, 0x1 }, /* 9, 78%*/ { 0x6, 0x2 }, /* 10, 70%*/ { 0x7, 0x2 }, /* 11, 73%*/ { 0x8, 0x2 }, /* 12, 75%*/ { 0x9, 0x2 }, /* 13, 77%*/ { 0x9, 0x3 }, /* 14, 71%*/ { 0xA, 0x3 }, /* 15, 73%*/ { 0xB, 0x3 }, /* 16, 75%*/ { 0xC, 0x3 }, /* 17, 76%*/ { 0xD, 0x3 }, /* 18, 78%*/ { 0xD, 0x4 }, /* 19, 74%*/ { 0xE, 0x4 }, /* 20, 75%*/ { 0xF, 0x4 }, /* 21, 76%*/ { 0xF, 0x5 }, /* 22, 73%*/ { 0xF, 0x6 }, /* 23, 70%*/ { 0xF, 0x7 }, /* 24, 67%*/ }; /** * @brief Checks if divisor is a divisor of value. * * @param value The number to be divided. * @param divisor The divisor to check. * * @return true if "number" is divided by "divisor"; false otherwise. */ static inline bool is_divisor( const uint32_t value, const uint16_t divisor ) { return ( ( value % divisor ) == 0 ); } /** * @brief Gets the size of the two tseg values added according to the given * bitwidth and brp (The CAN prescaler). * * @param bitwidth The total bitwidth of a CAN bit (in pclk clocks). * @param brp The CAN clock prescaler. * * @return The value of tseg1 + tseg2 of the CAN bit. It is useful * to serve for index for timing_pts array). */ static inline uint32_t get_tseg_bit_size( const uint32_t bitwidth, const uint16_t brp ) { return ( ( bitwidth / ( brp + CAN_BRP_EXTRA_BIT ) ) - CAN_TSEG_EXTRA_BITS ); } /** * @brief Gets the brp and tsegbitsize in order to achieve the desired bitwidth. * @details The following must be fullfilled: *(brp + CAN_BRP_EXTRA_BIT) * (tsegbitsize + CAN_TSEG_EXTRA_BITS) == bitwidth * * @param bitwidth The bitwidth that we need to achieve. * @param brp Here it returns the calculated brp value. * @param tsegbitsize Here it returns the calculated tseg bit size value. * @return true if brp and tsegbitsize have been calculated. */ static inline bool get_brp_and_bitsize( const uint32_t bitwidth, uint16_t *const brp, uint32_t *const tsegbitsize ) { bool hit = false; while ( ( !hit ) && ( *brp < bitwidth / MIN_NUMBER_OF_CAN_BITS ) ) { if ( ( is_divisor( bitwidth, *brp + CAN_BRP_EXTRA_BIT ) ) && ( get_tseg_bit_size( bitwidth, *brp ) < MAX_TSEG1_TSEG2_BITS ) ) { hit = true; *tsegbitsize = get_tseg_bit_size( bitwidth, *brp ); } else { /*Correct values not found, keep looking*/ ( *brp )++; } } return hit; } /** * @brief Constructs the btr register with the passed arguments. * * @param tsegbitsize The size tseg bits to set. * @param psjw The sjw to set. * @param brp The prescaler value to set. * @return The constructed btr register. */ static inline uint32_t get_btr( const uint32_t tsegbitsize, const unsigned char psjw, const uint32_t brp ) { const uint32_t tseg2_value_masked = ( ( timing_pts[ tsegbitsize ][ CAN_TSEG2 ] << CAN_BTR_TSEG2_SHIFT ) & CAN_BTR_TSEG2_MASK ); const uint32_t tseg1_value_masked = ( ( timing_pts[ tsegbitsize ][ CAN_TSEG1 ] << CAN_BTR_TSEG1_SHIFT ) & CAN_BTR_TSEG1_MASK ); const uint32_t psjw_value_masked = ( ( psjw << CAN_BTR_SJW_SHIFT ) & CAN_BTR_SJW_MASK ); const uint32_t brp_value_masked = ( ( brp << CAN_BTR_BRP_SHIFT ) & CAN_BTR_BRP_MASK ); return tseg1_value_masked | tseg2_value_masked | psjw_value_masked | brp_value_masked; } /** * @brief Calculates and returns a bit timing register (btr) for the desired * canclk frequency using the passed psjw, system clock and peripheral clock. * * @param systemclk The clock of the system (in Hz). * @param pclkdiv The peripheral clock divisor for the can device. * @param canclk The desired frequency for CAN (in Hz). * @param psjw The desired psjw. * @return The btr register value if found, WRONG_BTR_VALUE otherwise. */ static inline unsigned int can_speed( const unsigned int systemclk, const unsigned int pclkdiv, const unsigned int canclk, const unsigned char psjw ) { uint32_t btr = WRONG_BTR_VALUE; const uint32_t bitwidth = systemclk / ( pclkdiv * canclk ); /* This is for the brp (prescaler) to start searching a reachable multiple.*/ uint16_t brp = bitwidth / MAX_NUMBER_OF_CAN_BITS; uint32_t tsegbitsize; if ( get_brp_and_bitsize( bitwidth, &brp, &tsegbitsize ) ) { btr = get_btr( tsegbitsize, psjw, brp ); } return btr; } /** * @brief Configures the desired CAN device with the desired frequency. * * @param obj The can device to configure. * @param f The desired frequency. * * @return RTEMS_SUCCESSFUL if could be set, RTEMS_INVALID_NUMBER otherwise. */ static rtems_status_code can_frequency( const can_driver_entry *const obj, const can_freq freq ) { rtems_status_code sc = RTEMS_INVALID_NUMBER; const uint32_t btr = can_speed( LPC176X_CCLK, LPC176X_PCLKDIV, freq, 1 ); if ( btr != WRONG_BTR_VALUE ) { sc = RTEMS_SUCCESSFUL; uint32_t modmask = can_disable( obj ); obj->device->BTR = btr; obj->device->MOD = modmask; } /*else couldnt found a good timing for the desired frequency, return RTEMS_INVALID_NUMBER.*/ return sc; } /** * @brief Installs the interrupt handler in rtems. */ static inline rtems_status_code can_initialize( void ) { return rtems_interrupt_handler_install( LPC176X_IRQ_CAN, "can_interrupt", RTEMS_INTERRUPT_UNIQUE, can_isr, NULL ); } rtems_status_code can_open( const lpc176x_can_number minor, can_freq freq ) { const can_driver_entry *const can_driver = &can_driver_table[ minor ]; rtems_status_code sc = RTEMS_INVALID_NUMBER; if ( CAN_DRIVER_IS_MINOR_VALID( minor ) ) { /*Enable CAN and acceptance filter modules.*/ sc = lpc176x_module_enable( can_driver->module, LPC176X_MODULE_PCLK_DEFAULT ); RTEMS_CHECK_SC( sc, "enable can module" ); sc = lpc176x_module_enable( LPC176X_MODULE_ACCF, LPC176X_MODULE_PCLK_DEFAULT ); RTEMS_CHECK_SC( sc, "enable acceptance filter" ); /*Set pin functions.*/ setpins( minor ); can_reset( can_driver ); can_driver->device->IER = CAN_DEFAULT_INTERRUPT_CONFIGURATION; sc = can_frequency( can_driver, freq ); RTEMS_CHECK_SC( sc, "Configure CAN frequency" ); can_initialize(); acceptance_filter_device->AFMR = CAN_ACCF_AFMR_ACCBP; /*Bypass Filter.*/ } return sc; } /** * @brief Calls the installed isrs, according to the active interrupts. * * @param vector The read vector of active interrupts. * @param number The CAN device to look for interruptions. */ static inline void call_isrs( const uint32_t vector, const lpc176x_can_number number ) { can_irq_type i; for ( i = IRQ_RX; i < CAN_IRQ_NUMBER; ++i ) { if ( ( isr_vector[ i ] != NULL ) && ( vector & ( 1 << i ) ) ) isr_vector[ i ]( number ); /* else this interrupt has not been raised or it hasn't got a handler, so do nothing.*/ } } /** * @brief Checks if the passed CAN device is enabled and if it is checks for * active interrupts and calls its installed isr. * * @param number The CAN device to check for interrupts rised. */ static inline void search_and_call_int( const lpc176x_can_number number ) { const can_driver_entry *const driver = &can_driver_table[ number ]; if ( LPC176X_SCB.pconp & driver->pconp_pin ) { /*We must read the whole register at once because it resets when read.*/ const uint32_t int_vector = driver->device->ICR & CAN_INTERRUPT_TYPE_MASK; call_isrs( int_vector, number ); } /*else the device is shut down so we must do nothing.*/ } /** * @brief The standard isr to be installed for all the CAN devices. * * @param arg unused. */ static void can_isr( void *arg ) { lpc176x_can_number i; for ( i = CAN_0; i < CAN_DEVICES_NUMBER; ++i ) { search_and_call_int( i ); } } rtems_status_code can_read( const lpc176x_can_number minor, can_message *message ) { rtems_status_code sc = RTEMS_IO_ERROR; const can_driver_entry *const can_driver = &can_driver_table[ minor ]; can_device *const dev = can_driver->device; registers_can_message *const msg = &( message->registers ); can_enable( can_driver ); if ( dev->GSR & CAN_GSR_RBS_MASK ) { sc = RTEMS_SUCCESSFUL; *msg = dev->receive; dev->CMR = CAN_CMR_RRB_MASK; /* release receive buffer. */ } /* else Message not received.*/ return sc; } /** * @brief Array of masks and control bits for the transmit buffers. * It's used for each transmit buffer in order to see if it's available and to * send data to them. */ static const can_transmit_info transmit_info[ CAN_NUMBER_OF_TRANSMIT_BUFFERS ] = { { .can_status_mask = 0x00000004U, .not_cc_cmr_value = 0x21U }, { .can_status_mask = 0x00000400U, .not_cc_cmr_value = 0x41U }, { .can_status_mask = 0x00040000U, .not_cc_cmr_value = 0x81U } }; rtems_status_code can_write( const lpc176x_can_number minor, const can_message *const message ) { const can_driver_entry *const can_driver = &can_driver_table[ minor ]; can_device *const obj = can_driver->device; const uint32_t CANStatus = obj->SR; const registers_can_message *const msg = &( message->registers ); rtems_status_code sc = RTEMS_IO_ERROR; can_transmit_number transmit_buffer; can_enable( can_driver ); for ( transmit_buffer = CAN_TRANSMIT1; ( sc != RTEMS_SUCCESSFUL ) && ( transmit_buffer < CAN_NUMBER_OF_TRANSMIT_BUFFERS ); ++transmit_buffer ) { if ( CANStatus & transmit_info[ transmit_buffer ].can_status_mask ) { sc = RTEMS_SUCCESSFUL; obj->transmit[ transmit_buffer ] = *msg; obj->CMR = transmit_info[ transmit_buffer ].not_cc_cmr_value; } /*else can buffer busy, try with the next.*/ } return sc; } /** * @brief Enables the interrupt type passed to the desired CAN device. * * @param number The CAN device to enable the interrupts. * @param type The type of interrupt to enable. */ static inline void can_enable_interrupt( const lpc176x_can_number number, const can_irq_type type ) { const can_driver_entry *const driver = &can_driver_table[ number ]; const uint32_t ier = 1 << type; can_disable( driver ); driver->device->IER |= ier; can_enable( driver ); } rtems_status_code can_register_isr( const lpc176x_can_number number, const can_irq_type type, const lpc176x_can_isr isr ) { rtems_status_code sc = RTEMS_INVALID_NUMBER; if ( ( 0 <= type ) && ( type < CAN_IRQ_NUMBER ) ) { sc = RTEMS_SUCCESSFUL; isr_vector[ type ] = isr; can_enable_interrupt( number, type ); } return sc; } rtems_status_code create_can_message( can_message *const msg, const int _id, const char *const _data, const char _len ) { rtems_status_code sc = RTEMS_INVALID_NUMBER; if ( ( _len <= CAN_MAXIMUM_DATA_SIZE ) && ( _id <= CAN10_MAXIMUM_ID ) ) { sc = RTEMS_SUCCESSFUL; msg->low_level.dlc = _len; msg->low_level.type = CANStandard; msg->low_level.rtr = CANData; msg->low_level.id = _id; memcpy( msg->low_level.data, _data, _len ); } return sc; }