flash.c

00001 /****************************************************************************
00002  *    Copyright 2010 Andy Kirkham, Stellar Technologies Ltd
00003  *    
00004  *    This file is part of the Satellite Observers Workbench (SOWB).
00005  *
00006  *    SOWB is free software: you can redistribute it and/or modify
00007  *    it under the terms of the GNU General Public License as published by
00008  *    the Free Software Foundation, either version 3 of the License, or
00009  *    (at your option) any later version.
00010  *
00011  *    SOWB is distributed in the hope that it will be useful,
00012  *    but WITHOUT ANY WARRANTY; without even the implied warranty of
00013  *    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
00014  *    GNU General Public License for more details.
00015  *
00016  *    You should have received a copy of the GNU General Public License
00017  *    along with SOWB.  If not, see <http://www.gnu.org/licenses/>.
00018  *
00019  *    $Id: main.cpp 5 2010-07-12 20:51:11Z ajk $
00020  *    
00021  ***************************************************************************/
00022 
00023 #include "sowb.h"
00024 #include "debug.h"
00025 #include "ssp0.h"
00026 #include "gpio.h"
00027 #include "flash.h"
00028 #include "user.h"
00029 
00030 extern bool sector_erase_in_progress;
00031 extern bool page_write_in_progress;
00032 
00033 char flash_buffer[2][FLASH_PAGE_SIZE];
00034 int current_buffer;
00035 unsigned int flash_address;
00036 
00037 /** flash_init
00038  */
00039 void flash_init(void) {
00040     
00041     /* Initialise the SSP0 to talk to the flash device. */    
00042     SSP0_init();
00043     
00044     DEBUG_INIT_START;
00045     
00046     /* Clear out the page buffers. */
00047     memset(flash_buffer, 0, 2 * FLASH_PAGE_SIZE);
00048     
00049     /* Default the buffer in use. */
00050     current_buffer = 0;
00051     
00052     /* Default pointer set-up. */
00053     flash_address = 0;
00054     
00055     /* Prime our buffers for expected future access. */
00056     flash_read_page(0, flash_buffer[0], true);
00057     flash_read_page(1, flash_buffer[1], true);
00058     
00059     /* Although not part of the flash system, SOWB includes
00060        a 25AA02E48 device from Microchip that holds a globally
00061        unique 48bit (6byte) MAC address. We use this for the
00062        SOWB "STL authentic product" serial number and in future
00063        may be used as the ethernet MAC address if we ever write 
00064        code to support Ethernet. This device is also connected
00065        to SSP1 and so we'll _init() it here now. */
00066     //_25AA02E48_init();
00067     
00068     DEBUG_INIT_END;
00069 }
00070 
00071 /** flash_process
00072  */
00073 void flash_process(void) {
00074     /* Currently does nothing. */
00075 }
00076 
00077 /** flash_getc
00078  */
00079 char flash_getc(bool peek) {
00080     char c;
00081     
00082     /* Flash being deleted, undefined memory. */
00083     if (sector_erase_in_progress) return 0xFF;
00084     
00085     /* Wait for any page loads to complete. */
00086     while (page_write_in_progress) user_call_process();
00087     
00088     /* Get the character from the internal buffer. */
00089     c = flash_buffer[current_buffer][flash_address];
00090     
00091     /* If this is just a peek then return the character without
00092        incrementing the memory pointers etc etc. */
00093     if (peek) return c;
00094     
00095     /* Inc the address pointer and load a new page if needed. Note,
00096        we load the page in background using DMA. */
00097     flash_address++;
00098     if ((flash_address & 0xFF) == 0) {
00099         flash_read_page(current_buffer >> 8, flash_buffer[current_buffer], false);
00100         current_buffer = current_buffer ? 0 : 1;        
00101     }
00102     
00103     return c;
00104 }
00105 
00106 /** flash_seek
00107  */
00108 void flash_seek(unsigned int addr) {
00109     flash_read_page((addr >> 8) + 0, flash_buffer[0], true);
00110     flash_read_page((addr >> 8) + 1, flash_buffer[1], true);
00111     flash_address = addr;
00112 }