mpc55xxevb/start/emios.c

0001 /* SPDX-License-Identifier: BSD-2-Clause */
0002
0003 /**
0004  * @file
0005  *
0006  * @ingroup RTEMSBSPsPowerPCMPC55XX
0007  *
0008  * @brief Enhanced Modular Input Output Subsystem (eMIOS).
0009  */
0010
0011 /*
0012  * Copyright (C) 2009, 2011 embedded brains GmbH & Co. KG
0013  *
0014  * Redistribution and use in source and binary forms, with or without
0015  * modification, are permitted provided that the following conditions
0016  * are met:
0017  * 1. Redistributions of source code must retain the above copyright
0018  *    notice, this list of conditions and the following disclaimer.
0019  * 2. Redistributions in binary form must reproduce the above copyright
0020  *    notice, this list of conditions and the following disclaimer in the
0021  *    documentation and/or other materials provided with the distribution.
0022  *
0023  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
0024  * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
0025  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
0026  * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
0027  * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
0028  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
0029  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
0030  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
0031  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
0032  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
0033  * POSSIBILITY OF SUCH DAMAGE.
0034  */
0035
0036 #include <mpc55xx/emios.h>
0037
0038 #ifdef MPC55XX_HAS_EMIOS
0039
0040 /**
0041  * @brief Initialize the eMIOS module.
0042  *
0043  * The module is enabled.  It is configured to use the internal clock.  The
0044  * global prescaler value is set to @a prescaler.  If the value is greater than
0045  * the maximum the maxium value will be used instead.  A prescaler value of
0046  * zero disables the clock.
0047  *
0048  * @note No protection against concurrent execution.
0049  */
0050 void mpc55xx_emios_initialize( unsigned prescaler)
0051 {
0052   union EMIOS_MCR_tag mcr = MPC55XX_ZERO_FLAGS;
0053
0054   /* Enable module */
0055   mcr.B.MDIS = 0;
0056
0057   /* Disable debug mode */
0058   mcr.B.FRZ = 1;
0059
0060   /* Enable global time base */
0061   mcr.B.GTBE = 1;
0062
0063   /* Disable global prescaler (= disable clock) */
0064   mcr.B.GPREN = 0;
0065
0066   /* Set MCR */
0067   EMIOS.MCR.R = mcr.R;
0068
0069   /* Set OUDR */
0070   EMIOS.OUDR.R = 0;
0071
0072   /* Set global prescaler value */
0073   mpc55xx_emios_set_global_prescaler( prescaler);
0074 }
0075
0076 /**
0077  * @brief Returns the global prescaler value of the eMIOS module.
0078  */
0079 unsigned mpc55xx_emios_global_prescaler( void)
0080 {
0081   union EMIOS_MCR_tag mcr = EMIOS.MCR;
0082
0083   if (mcr.B.GPREN != 0) {
0084     return mcr.B.GPRE + 1;
0085   } else {
0086     return 0;
0087   }
0088 }
0089
0090 /**
0091  * @brief Sets the global prescaler value of the eMIOS module.
0092  *
0093  * The global prescaler value is set to @a prescaler.  If the value is greater
0094  * than the maximum the maxium value will be used instead.  A prescaler value
0095  * of zero disables the clock.
0096  *
0097  * @note No protection against concurrent execution.
0098  */
0099 void mpc55xx_emios_set_global_prescaler( unsigned prescaler)
0100 {
0101   union EMIOS_MCR_tag mcr = EMIOS.MCR;
0102
0103   /* Enable or disable the global prescaler */
0104   mcr.B.GPREN = prescaler > 0 ? 1 : 0;
0105
0106   /* Set global prescaler value */
0107   if (prescaler > 256) {
0108     prescaler = 256;
0109   } else if (prescaler < 1) {
0110     prescaler = 1;
0111   }
0112   mcr.B.GPRE = prescaler - 1;
0113
0114   /* Set MCR */
0115   EMIOS.MCR.R = mcr.R;
0116 }
0117
0118 #endif /* MPC55XX_HAS_EMIOS */