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/*
* stm-fmc.c
* ---------
* Functions to set up and use the FMC bus.
*
* Copyright (c) 2015, NORDUnet A/S All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are
* met:
* - Redistributions of source code must retain the above copyright notice,
* this list of conditions and the following disclaimer.
*
* - 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.
*
* - Neither the name of the NORDUnet 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
* HOLDER 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.
*/
#include "stm-init.h"
#include "stm-fmc.h"
static SRAM_HandleTypeDef _fmc_fpga_inst;
void fmc_init(void)
{
static int initialized = 0;
if (initialized) return;
initialized = 1;
// configure fmc pins
GPIO_InitTypeDef GPIO_InitStruct;
// enable fmc clock
__HAL_RCC_FMC_CLK_ENABLE();
fmc_af_gpio(GPIOB, GPIO_PIN_7);
fmc_af_gpio(GPIOD, GPIO_PIN_0 | GPIO_PIN_1 | GPIO_PIN_3 | GPIO_PIN_4
| GPIO_PIN_5 | GPIO_PIN_7 | GPIO_PIN_8 | GPIO_PIN_9
| GPIO_PIN_10 | GPIO_PIN_11 | GPIO_PIN_12 | GPIO_PIN_13
| GPIO_PIN_14 | GPIO_PIN_15);
/*
* When FMC is working with fixed latency, NWAIT pin (PD6) must not be
* configured in AF mode, according to STM32F429 errata.
*/
GPIO_InitStruct.Pin = GPIO_PIN_6;
GPIO_InitStruct.Mode = GPIO_MODE_INPUT;
GPIO_InitStruct.Pull = GPIO_PULLUP;
HAL_GPIO_Init(GPIOD, &GPIO_InitStruct);
fmc_af_gpio(GPIOE, GPIO_PIN_2
| GPIO_PIN_3 | GPIO_PIN_4 | GPIO_PIN_5 | GPIO_PIN_6 | GPIO_PIN_7
| GPIO_PIN_8 | GPIO_PIN_9 | GPIO_PIN_10 | GPIO_PIN_11
| GPIO_PIN_12 | GPIO_PIN_13 |GPIO_PIN_14 | GPIO_PIN_15);
fmc_af_gpio(GPIOF, GPIO_PIN_0 | GPIO_PIN_1 | GPIO_PIN_2 | GPIO_PIN_3
| GPIO_PIN_4 | GPIO_PIN_5 | GPIO_PIN_12 | GPIO_PIN_13
| GPIO_PIN_14 | GPIO_PIN_15);
fmc_af_gpio(GPIOG, GPIO_PIN_0 | GPIO_PIN_1 | GPIO_PIN_2 | GPIO_PIN_3
| GPIO_PIN_4 | GPIO_PIN_5);
fmc_af_gpio(GPIOH, GPIO_PIN_8 | GPIO_PIN_9 | GPIO_PIN_10 | GPIO_PIN_11
| GPIO_PIN_12 | GPIO_PIN_13 | GPIO_PIN_14 | GPIO_PIN_15);
fmc_af_gpio(GPIOI, GPIO_PIN_0 | GPIO_PIN_1 | GPIO_PIN_2 | GPIO_PIN_3
| GPIO_PIN_6 | GPIO_PIN_7 | GPIO_PIN_9 | GPIO_PIN_10);
// configure fmc registers
/*
* fill internal fields
*/
_fmc_fpga_inst.Instance = FMC_NORSRAM_DEVICE;
_fmc_fpga_inst.Extended = FMC_NORSRAM_EXTENDED_DEVICE;
/*
* configure fmc interface settings
*/
// use the first bank and corresponding chip select
_fmc_fpga_inst.Init.NSBank = FMC_NORSRAM_BANK1;
// data and address buses are separate
_fmc_fpga_inst.Init.DataAddressMux = FMC_DATA_ADDRESS_MUX_DISABLE;
// fpga mimics psram-type memory
_fmc_fpga_inst.Init.MemoryType = FMC_MEMORY_TYPE_PSRAM;
// data bus is 32-bit
_fmc_fpga_inst.Init.MemoryDataWidth = FMC_NORSRAM_MEM_BUS_WIDTH_32;
// read transaction is sync
_fmc_fpga_inst.Init.BurstAccessMode = FMC_BURST_ACCESS_MODE_ENABLE;
// this _must_ be configured to high, according to errata, otherwise
// the processor may hang after trying to access fpga via fmc
_fmc_fpga_inst.Init.WaitSignalPolarity = FMC_WAIT_SIGNAL_POLARITY_HIGH;
// wrap mode is not supported
_fmc_fpga_inst.Init.WrapMode = FMC_WRAP_MODE_DISABLE;
// don't care in fixed latency mode
_fmc_fpga_inst.Init.WaitSignalActive = FMC_WAIT_TIMING_BEFORE_WS;
// allow write access to fpga
_fmc_fpga_inst.Init.WriteOperation = FMC_WRITE_OPERATION_ENABLE;
// use fixed latency mode (ignore wait signal)
_fmc_fpga_inst.Init.WaitSignal = FMC_WAIT_SIGNAL_DISABLE;
// write and read have same timing
_fmc_fpga_inst.Init.ExtendedMode = FMC_EXTENDED_MODE_DISABLE;
// don't care in sync mode
_fmc_fpga_inst.Init.AsynchronousWait = FMC_ASYNCHRONOUS_WAIT_DISABLE;
// write transaction is sync
_fmc_fpga_inst.Init.WriteBurst = FMC_WRITE_BURST_ENABLE;
// keep clock always active
_fmc_fpga_inst.Init.ContinuousClock = FMC_CONTINUOUS_CLOCK_SYNC_ASYNC;
/*
* configure fmc timing parameters
*/
FMC_NORSRAM_TimingTypeDef fmc_timing;
// don't care in sync mode
fmc_timing.AddressSetupTime = 15;
// don't care in sync mode
fmc_timing.AddressHoldTime = 15;
// don't care in sync mode
fmc_timing.DataSetupTime = 255;
// not needed, since nwait will be polled manually
fmc_timing.BusTurnAroundDuration = 0;
// use smallest allowed divisor for best performance
//
// FMC_CLK = HCLK / CLKDivision, HCLK is 180 MHz
//
// Allowed values for CLKDivision are integers >= 2.
//
// Division == 2: FMC_CLK = 180 / 2 = 90 MHz (highest allowed frequency)
// Division == 3: FMC_CLK = 180 / 3 = 60 MHz (one step below)
// ...
//
// fmc_timing.CLKDivision = 2; // 90 MHz
fmc_timing.CLKDivision = 3; // 60 MHz
// use min suitable for fastest transfer
fmc_timing.DataLatency = 4;
// don't care in sync mode
fmc_timing.AccessMode = FMC_ACCESS_MODE_A;
// initialize fmc
HAL_SRAM_Init(&_fmc_fpga_inst, &fmc_timing, NULL);
// STM32 only enables FMC clock right before the very first read/write
// access. FPGA takes certain time (<= 100 us) to lock its PLL to this frequency,
// so a certain number of initial FMC transactions may be missed. One read transaction
// takes ~0.1 us (9 ticks @ 90 MHz), so doing 1000 dummy reads will make sure, that FPGA
// has already locked its PLL and is ready. Another way around is to repeatedly read
// some register that is guaranteed to have known value until reading starts returning
// correct data.
// to prevent compiler from optimizing this away, we pretent we're calculating sum
int cyc;
uint32_t sum;
volatile uint32_t part;
for (cyc = 0; cyc < 1000; cyc++) {
part = *(__IO uint32_t *)FMC_FPGA_BASE_ADDR;
sum += part;
}
}
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