/****************************************************************************
* config/vsn/src/muxbus.c
* arch/arm/src/board/muxbus.c
*
* Copyright (C) 2011 Uros Platise. All rights reserved.
*
* Authors: Uros Platise <uros.platise@isotel.eu>
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in
* the documentation and/or other materials provided with the
* distribution.
* 3. Neither the name NuttX nor the names of its contributors may be
* used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
* OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
* AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
* ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*
****************************************************************************/
/** \file
* \author Uros Platise
* \brief VSN Multiplexed Bus, SDIO Interface and the Analog Front-End
*/
#include <nuttx/config.h>
#include <semaphore.h>
#include <errno.h>
#include "vsn.h"
#include "stm32_gpio.h"
/****************************************************************************
* Private data
****************************************************************************/
/** Set true when the bus has been locked by the SDIO interface */
bool vsn_muxbus_ownedbysdio;
/** Semaphore to resolve conflicts between muxbus locks */
sem_t vsn_muxbus_sem;
/****************************************************************************
* Private functions
****************************************************************************/
void vsn_muxbus_takeownership(void)
{
while (sem_wait(&vsn_muxbus_sem) != 0) {
/* The only case that an error should occr here is if the wait was
* awakened by a signal.
*/
ASSERT(errno == EINTR);
}
}
void vsn_muxbus_sdio_release(void)
{
stm32_unconfiggpio(GPIO_SDIO_D0);
stm32_unconfiggpio(GPIO_SDIO_CK);
stm32_unconfiggpio(GPIO_SDIO_CMD);
vsn_muxbus_ownedbysdio = FALSE;
}
void vsn_muxbus_sdio_access(void)
{
stm32_configgpio(GPIO_SDIO_D0);
stm32_configgpio(GPIO_SDIO_CK);
stm32_configgpio(GPIO_SDIO_CMD);
vsn_muxbus_ownedbysdio = TRUE;
}
/****************************************************************************
* Public functions
****************************************************************************/
void vsn_muxbus_init(void)
{
/* Put the PGA in default shut-down state */
stm32_configgpio(GPIO_PGIA_AEN);
/* setup semaphore in non-locked condition */
sem_init(&vsn_muxbus_sem, 0, 1);
/* by default give the bus to the SDIO */
vsn_muxbus_sdio_access();
}
/**
* We could do extra checks: who is the owner to prevent
* unlocking from SDIO side eventhough it was not locked
* by him, but temporarily by the PGA
*/
void stm32_muxbus_sdio_lock(bool lock)
{
if ( lock )
vsn_muxbus_takeownership();
else
sem_post(&vsn_muxbus_sem);
}
/**
* The following rules apply for the SDcard:
*
* - CMD serial line always starts with 0 (start-bit) and ends with 1 (stop-bit)
* The total length is always 48 bits protected by CRCs. When changing the
* gain, CMD must be seen as 1 on CK changes.
*
* - An alternative mechanism would be to use suspend/resume commands
*
* - If SDcard internal shift-register is 8-bit oriented there might be a need
* to shift 7 dummy bits to properly detect invalid start of packet
* (with start bit set as 1) to invalidate bus transitions (in case CK
* is changing).
*
* SDIO returns the bus in HiZ states, where CLK = 0, D = CMD = external pull-up
*/
int vsn_muxbus_setpgagain(int gain)
{
/* Shutdown the Analog Devices AD8231 and exit if gain is invalid */
stm32_gpiowrite(GPIO_PGIA_AEN, FALSE);
if (gain < 0 || gain > 7)
return -1;
vsn_muxbus_takeownership();
vsn_muxbus_sdio_release();
/* If we have to set CLK = 1, made that first as D, CMD are 1 by pull-ups */
if (gain & 2)
stm32_configgpio(GPIO_PGIA_A1_H);
else stm32_configgpio(GPIO_PGIA_A1_L);
/* Set the D and CMD bits */
if (gain & 1)
stm32_configgpio(GPIO_PGIA_A0_H);
else stm32_configgpio(GPIO_PGIA_A0_L);
if (gain & 4)
stm32_configgpio(GPIO_PGIA_A2_H);
else stm32_configgpio(GPIO_PGIA_A2_L);
/* Sample GAIN on rising edge */
stm32_gpiowrite(GPIO_PGIA_AEN, TRUE);
/* Release D and CMD pins to 1; however shorten rising edge actively */
stm32_gpiowrite(GPIO_PGIA_A0_H, TRUE);
stm32_gpiowrite(GPIO_PGIA_A2_H, TRUE);
stm32_unconfiggpio(GPIO_PGIA_A0_H);
stm32_unconfiggpio(GPIO_PGIA_A2_H);
/* Release CLK by going down and return the bus */
stm32_unconfiggpio(GPIO_PGIA_A1_L);
vsn_muxbus_sdio_access();
sem_post(&vsn_muxbus_sem);
return gain;
}
