grlib/uart/apbuart_polled.c

0001 /* SPDX-License-Identifier: BSD-2-Clause */
0002
0003 /**
0004  * @file
0005  *
0006  * @ingroup RTEMSDeviceGRLIBAPBUART
0007  *
0008  * @brief This source file contains the implementation of
0009  *   apbuart_outbyte_wait(), apbuart_outbyte_polled(), and
0010  *   apbuart_inbyte_nonblocking().
0011  */
0012
0013 /*
0014  * Copyright (C) 2021 embedded brains GmbH & Co. KG
0015  *
0016  * Redistribution and use in source and binary forms, with or without
0017  * modification, are permitted provided that the following conditions
0018  * are met:
0019  * 1. Redistributions of source code must retain the above copyright
0020  *    notice, this list of conditions and the following disclaimer.
0021  * 2. Redistributions in binary form must reproduce the above copyright
0022  *    notice, this list of conditions and the following disclaimer in the
0023  *    documentation and/or other materials provided with the distribution.
0024  *
0025  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
0026  * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
0027  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
0028  * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
0029  * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
0030  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
0031  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
0032  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
0033  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
0034  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
0035  * POSSIBILITY OF SUCH DAMAGE.
0036  */
0037
0038 #include <grlib/apbuart.h>
0039 #include <grlib/io.h>
0040
0041 #include <rtems/dev/io.h>
0042
0043 void apbuart_outbyte_wait( const apbuart *regs )
0044 {
0045   while ( ( grlib_load_32( &regs->status ) & APBUART_STATUS_TE ) == 0 ) {
0046     _IO_Relax();
0047   }
0048 }
0049
0050 void apbuart_outbyte_polled( apbuart *regs, char ch)
0051 {
0052   apbuart_outbyte_wait( regs );
0053   grlib_store_32( &regs->data, (uint8_t) ch );
0054 }
0055
0056 int apbuart_inbyte_nonblocking( apbuart *regs )
0057 {
0058   uint32_t status;
0059
0060   status = grlib_load_32( &regs->status );
0061
0062   /* Clear errors, writes to non-error flags are ignored */
0063   status &= ~( APBUART_STATUS_FE | APBUART_STATUS_PE | APBUART_STATUS_OV |
0064     APBUART_STATUS_BR );
0065   grlib_store_32( &regs->status, status );
0066
0067   if ( ( status & APBUART_STATUS_DR ) == 0 ) {
0068     return -1;
0069   }
0070
0071   return (int) APBUART_DATA_DATA_GET( grlib_load_32( &regs->data ) );
0072 }