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 /**
  * @file
  *
  * @ingroup RTEMSBSPsARMLPC176X
  *
  * @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 <rtems/status-checks.h>
 #include <bsp/irq.h>
 #include <bsp/can.h>
 #include <bsp/can-defs.h>
 #include <bsp/mbed-pinmap.h>
 #include <string.h>
 
 /**
  * @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;
 }
 

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