/** * \file : sdcard.c * \date : 30 August 2012 * \author : Cesar Fuguet * * This file defines the driver of a SD Card device using an SPI controller */ #include /** * \param sdcard: Initialized pointer to the block device * * \return void * * \brief Enable SD Card select signal */ static void _sdcard_enable(struct sdcard_dev * sdcard) { spi_ss_assert(sdcard->spi, sdcard->slave_id); } /** * \param sdcard: Initialized pointer to the block device * * \return void * * \brief Disable SD Card select signal */ static void _sdcard_disable(struct sdcard_dev * sdcard) { spi_ss_deassert(sdcard->spi, sdcard->slave_id); } /** * \param tick_count: SD Card clock ticks number * * \return void * * \brief Enable SD Card clock * The tick count is byte measured (1 tick, 8 clock) */ static void _sdcard_gen_tick(struct sdcard_dev * sdcard, unsigned int tick_count) { register int i = 0; while(i++ < tick_count) spi_put_tx(sdcard->spi, 0xFF, 0); } /** * \param sdcard: Initialized pointer to the block device * * \return char from the SD card * * \brief Get a byte from the SD Card */ static unsigned char _sdcard_receive_char(struct sdcard_dev * sdcard) { _sdcard_gen_tick(sdcard, 1); return spi_get_rx(sdcard->spi, 0); } /** * \param sdcard: Initialized pointer to the block device * * \return sdcard response * * \brief Wait for a valid response after the send of a command * This function can return if one of the next two conditions are true: * 1. Bit valid received * 2. Timeout (not valid bit received after SDCARD_COMMAND_TIMEOUT * wait ticks) */ static unsigned char _sdcard_wait_response(struct sdcard_dev * sdcard) { unsigned char sdcard_rsp; register int iter; iter = 0; sdcard_rsp = _sdcard_receive_char(sdcard); while ( (iter < SDCARD_COMMAND_TIMEOUT) && !SDCARD_CHECK_R1_VALID(sdcard_rsp) ) { sdcard_rsp = _sdcard_receive_char(sdcard); iter++; } return sdcard_rsp; } /** * \params sdcard: Initialized pointer to the block device * * \return void * * \brief Wait data block start marker */ static void _sdcard_wait_data_block(struct sdcard_dev * sdcard) { while (_sdcard_receive_char(sdcard) != 0xFE); } /** * \param sdcard : Initialized pointer to block device * \param index : SD card CMD index * \param app : Type of command, 0 for normal command or 1 for application specific * \param args : SD card CMD arguments * * \return response first byte * * \brief Send command to the SD card */ static int _sdcard_send_command ( struct sdcard_dev * sdcard , int index , int app , void * args , unsigned crc7 ) { unsigned char sdcard_rsp; unsigned char * _args; _sdcard_gen_tick(sdcard, 5); if (app == SDCARD_ACMD) { spi_put_tx(sdcard->spi, 0x40 | 55 , 0 );/* CMD and START bit */ spi_put_tx(sdcard->spi, 0x00 , 0 );/* Argument[0] */ spi_put_tx(sdcard->spi, 0x00 , 0 );/* Argument[1] */ spi_put_tx(sdcard->spi, 0x00 , 0 );/* Argument[2] */ spi_put_tx(sdcard->spi, 0x00 , 0 );/* Argument[3] */ spi_put_tx(sdcard->spi, 0x01 | (crc7 << 1), 0 );/* END bit */ sdcard_rsp = _sdcard_wait_response(sdcard); if (SDCARD_CHECK_R1_ERROR(sdcard_rsp)) { return sdcard_rsp; } } _args = (unsigned char *) args; _sdcard_gen_tick(sdcard, 1); spi_put_tx(sdcard->spi, 0x40 | index , 0 ); spi_put_tx(sdcard->spi, _args[0] , 0 ); spi_put_tx(sdcard->spi, _args[1] , 0 ); spi_put_tx(sdcard->spi, _args[2] , 0 ); spi_put_tx(sdcard->spi, _args[3] , 0 ); spi_put_tx(sdcard->spi, 0x01 | (crc7 << 1), 0 ); return _sdcard_wait_response(sdcard); } int sdcard_dev_open(struct sdcard_dev * sdcard, struct spi_dev * spi, int ss) { unsigned char args[4]; unsigned char sdcard_rsp; unsigned int iter; sdcard->spi = spi; sdcard->slave_id = ss; /* * Supply SD card ramp up time (min 74 cycles) */ _sdcard_gen_tick(sdcard, 10); /* * Assert slave select signal * Send CMD0 (Reset Command) * Deassert slave select signal */ _sdcard_enable(sdcard); args[0] = 0; args[1] = 0; args[2] = 0; args[3] = 0; sdcard_rsp = _sdcard_send_command(sdcard, 0, SDCARD_CMD, args, 0x4A); if ( sdcard_rsp != 0x01 ) { return sdcard_rsp; } _sdcard_disable(sdcard); _sdcard_enable(sdcard); iter = 0; while( iter++ < SDCARD_COMMAND_TIMEOUT ) { sdcard_rsp = _sdcard_send_command(sdcard, 41, SDCARD_ACMD, args, 0x00); if( sdcard_rsp == 0x01 ) { continue; } break; } _sdcard_disable(sdcard); return sdcard_rsp; } int sdcard_dev_read(struct sdcard_dev * sdcard, void * buf, unsigned int count) { unsigned char args[4]; unsigned char sdcard_rsp; register int i; for (i = 0; i < 4; i++) { args[i] = (sdcard->access_pointer >> (32 - (i+1)*8)) & 0xFF; } _sdcard_enable(sdcard); sdcard_rsp = _sdcard_send_command(sdcard, 17, SDCARD_CMD, args, 0x00); if ( SDCARD_CHECK_R1_ERROR(sdcard_rsp) ) { _sdcard_disable(sdcard); return sdcard_rsp; } _sdcard_wait_data_block(sdcard); for ( i = 0; i < count; i++ ) { *((char *) buf + i) = _sdcard_receive_char(sdcard); } /* * Get the remainder of the block bytes and the CRC16 (comes * at the end of the data block) */ while( i++ < (sdcard->block_length + 2) ) _sdcard_receive_char(sdcard); _sdcard_disable(sdcard); /* * Move the access pointer to the next block */ sdcard->access_pointer += sdcard->block_length; return 0; } unsigned int sdcard_dev_write(struct sdcard_dev *sdcard, void * buf, unsigned int count) { return 0; } void sdcard_dev_lseek(struct sdcard_dev * sdcard, unsigned int blk_pos) { sdcard->access_pointer = sdcard->block_length * blk_pos; } unsigned int sdcard_dev_get_capacity(struct sdcard_dev * sdcard) { return sdcard->capacity; } int sdcard_dev_set_blocklen(struct sdcard_dev * sdcard, unsigned int len) { unsigned char args[4]; unsigned char sdcard_rsp; register int i; for (i = 0; i < 4; i++) args[i] = (len >> (32 - (i+1)*8)) & 0xFF; _sdcard_enable(sdcard); sdcard_rsp = _sdcard_send_command(sdcard, 16, SDCARD_CMD, args, 0x00); if ( SDCARD_CHECK_R1_ERROR(sdcard_rsp) ) { _sdcard_disable(sdcard); return sdcard_rsp; } _sdcard_disable(sdcard); sdcard->block_length = len; return 0; } /* * vim: tabstop=4 : shiftwidth=4 : expandtab : softtabstop=4 */