nuttx/configs/stm3220g-eval/src/stm32_selectsram.c

/************************************************************************************
 * configs/stm3220g-eval/src/stm32_selectsram.c
 *
 *   Copyright (C) 2012 Gregory Nutt. All rights reserved.
 *   Author: Gregory Nutt <gnutt@nuttx.org>
 *
 * 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.
 *
 ************************************************************************************/

/************************************************************************************
 * Included Files
 ************************************************************************************/

#include <nuttx/config.h>

#include <stdint.h>
#include <debug.h>

#include "chip.h"
#include "up_arch.h"

#include "stm32.h"
#include "stm3220g-eval.h"

#ifdef CONFIG_STM32_FSMC

/************************************************************************************
 * Pre-processor Definitions
 ************************************************************************************/

#if STM32_NGPIO_PORTS < 6
#  error "Required GPIO ports not enabled"
#endif

/* SRAM Timing */

#define SRAM_ADDRESS_SETUP_TIME      3
#define SRAM_ADDRESS_HOLD_TIME       0
#define SRAM_DATA_SETUP_TIME         6
#define SRAM_BUS_TURNAROUND_DURATION 1
#define SRAM_CLK_DIVISION            0
#define SRAM_DATA_LATENCY            0

/* SRAM pin definitions */

#define SRAM_NADDRLINES              21
#define SRAM_NDATALINES              16

/************************************************************************************
 * Public Data
 ************************************************************************************/

/************************************************************************************
 * Private Data
 ************************************************************************************/
/* GPIOs Configuration **************************************************************
 * PD0  <-> FSMC_D2    PE0  <-> FSMC_NBL0   PF0  <-> FSMC_A0   PG0 <-> FSMC_A10
 * PD1  <-> FSMC_D3    PE1  <-> FSMC_NBL1   PF1  <-> FSMC_A1   PG1 <-> FSMC_A11
 * PD4  <-> FSMC_NOE   PE3  <-> FSMC_A19    PF2  <-> FSMC_A2   PG2 <-> FSMC_A12
 * PD5  <-> FSMC_NWE   PE4  <-> FSMC_A20    PF3  <-> FSMC_A3   PG3 <-> FSMC_A13
 * PD8  <-> FSMC_D13   PE7  <-> FSMC_D4     PF4  <-> FSMC_A4   PG4 <-> FSMC_A14
 * PD9  <-> FSMC_D14   PE8  <-> FSMC_D5     PF5  <-> FSMC_A5   PG5 <-> FSMC_A15
 * PD10 <-> FSMC_D15   PE9  <-> FSMC_D6     PF12 <-> FSMC_A6   PG9 <-> FSMC_NE2
 * PD11 <-> FSMC_A16   PE10 <-> FSMC_D7     PF13 <-> FSMC_A7
 * PD12 <-> FSMC_A17   PE11 <-> FSMC_D8     PF14 <-> FSMC_A8
 * PD13 <-> FSMC_A18   PE12 <-> FSMC_D9     PF15 <-> FSMC_A9
 * PD14 <-> FSMC_D0    PE13 <-> FSMC_D10
 * PD15 <-> FSMC_D1    PE14 <-> FSMC_D11
 *                     PE15 <-> FSMC_D12
 */

/* GPIO configurations unique to SRAM  */

static const uint32_t g_sramconfig[] =
{
  /* NE3, NBL0, NBL1,  */

  GPIO_FSMC_NOE, GPIO_FSMC_NWE, GPIO_FSMC_NBL0, GPIO_FSMC_NBL1, GPIO_FSMC_NE2
};
#define NSRAM_CONFIG (sizeof(g_sramconfig)/sizeof(uint32_t))

/************************************************************************************
 * Private Functions
 ************************************************************************************/

/************************************************************************************
 * Public Functions
 ************************************************************************************/

/************************************************************************************
 * Name: stm32_selectsram
 *
 * Description:
 *   Initialize to access external SRAM.  SRAM will be visible at the FSMC Bank
 *   NOR/SRAM2 base address (0x64000000)
 *
 *   General transaction rules.  The requested AHB transaction data size can be 8-,
 *   16- or 32-bit wide whereas the SRAM has a fixed 16-bit data width. Some simple
 *   transaction rules must be followed:
 *
 *   Case 1: AHB transaction width and SRAM data width are equal
 *     There is no issue in this case.
 *   Case 2: AHB transaction size is greater than the memory size
 *     In this case, the FSMC splits the AHB transaction into smaller consecutive
 *     memory accesses in order to meet the external data width.
 *   Case 3: AHB transaction size is smaller than the memory size.
 *     SRAM supports the byte select feature.
 *     a) FSMC allows write transactions accessing the right data through its
 *        byte lanes (NBL[1:0])
 *     b) Read transactions are allowed (the controller reads the entire memory
 *        word and uses the needed byte only). The NBL[1:0] are always kept low
 *        during read transactions.
 *
 ************************************************************************************/

void stm32_selectsram(void)
{
  /* Configure new GPIO pins */

  stm32_extmemaddr(SRAM_NADDRLINES);              /* Common address lines: A0-A20 */
  stm32_extmemdata(SRAM_NDATALINES);              /* Common data lines: D0-D15 */
  stm32_extmemgpios(g_sramconfig, NSRAM_CONFIG);  /* SRAM-specific control lines */

  /* Enable AHB clocking to the FSMC */

  stm32_enablefsmc();

  /* Bank1 NOR/SRAM control register configuration
   *
   *   Bank enable        : Not yet
   *   Data address mux   : Disabled
   *   Memory Type        : PSRAM
   *   Data bus width     : 16-bits
   *   Flash access       : Disabled
   *   Burst access mode  : Disabled
   *   Polarity           : Low
   *   Wrapped burst mode : Disabled
   *   Write timing       : Before state
   *   Write enable       : Yes
   *   Wait signal        : Disabled
   *   Extended mode      : Disabled
   *   Asynchronous wait  : Disabled
   *   Write burst        : Disabled
   */

  putreg32((FSMC_BCR_PSRAM | FSMC_BCR_MWID16 | FSMC_BCR_WREN), STM32_FSMC_BCR2);

  /* Bank1 NOR/SRAM timing register configuration */

  putreg32((FSMC_BTR_ADDSET(SRAM_ADDRESS_SETUP_TIME) | FSMC_BTR_ADDHLD(SRAM_ADDRESS_HOLD_TIME) |
            FSMC_BTR_DATAST(SRAM_DATA_SETUP_TIME)    | FSMC_BTR_BUSTURN(SRAM_BUS_TURNAROUND_DURATION) |
            FSMC_BTR_CLKDIV(SRAM_CLK_DIVISION)       | FSMC_BTR_DATLAT(SRAM_DATA_LATENCY) |
            FSMC_BTR_ACCMODA),
           STM32_FSMC_BTR2);

  /* Bank1 NOR/SRAM timing register for write configuration, if extended mode is used */

  putreg32(0xffffffff, STM32_FSMC_BWTR2);  /* Extended mode not used */

  /* Enable the bank */

  putreg32((FSMC_BCR_MBKEN | FSMC_BCR_PSRAM | FSMC_BCR_MWID16 | FSMC_BCR_WREN), STM32_FSMC_BCR2);
}

#endif /* CONFIG_STM32_FSMC */