From: notaz Date: Thu, 21 Sep 2017 21:46:42 +0000 (+0300) Subject: import SPI EEPROM from Genesis-Plus-GX X-Git-Tag: v1.92~37 X-Git-Url: https://notaz.gp2x.de/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=8c2137f11f1b73f35f688f068de89b40b1f10484;p=picodrive.git import SPI EEPROM from Genesis-Plus-GX Author: EkeEke --- diff --git a/pico/carthw/eeprom_spi.c b/pico/carthw/eeprom_spi.c new file mode 100644 index 00000000..921eb6ab --- /dev/null +++ b/pico/carthw/eeprom_spi.c @@ -0,0 +1,358 @@ +/**************************************************************************** + * Genesis Plus + * SPI Serial EEPROM (25xxx/95xxx) support + * + * Copyright (C) 2012 Eke-Eke (Genesis Plus GX) + * + * Redistribution and use of this code or any derivative works are permitted + * provided that the following conditions are met: + * + * - Redistributions may not be sold, nor may they be used in a commercial + * product or activity. + * + * - Redistributions that are modified from the original source must include the + * complete source code, including the source code for all components used by a + * binary built from the modified sources. However, as a special exception, the + * source code distributed need not include anything that is normally distributed + * (in either source or binary form) with the major components (compiler, kernel, + * and so on) of the operating system on which the executable runs, unless that + * component itself accompanies the executable. + * + * - Redistributions 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. + * + * 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. + * + ****************************************************************************************/ + +#include "shared.h" + +/* max supported size 64KB (25x512/95x512) */ +#define SIZE_MASK 0xffff +#define PAGE_MASK 0x7f + +/* hard-coded board implementation (!WP pin not used) */ +#define BIT_DATA (0) +#define BIT_CLK (1) +#define BIT_HOLD (2) +#define BIT_CS (3) + +typedef enum +{ + STANDBY, + GET_OPCODE, + GET_ADDRESS, + WRITE_BYTE, + READ_BYTE +} T_STATE_SPI; + +typedef struct +{ + uint8 cs; /* !CS line state */ + uint8 clk; /* SCLK line state */ + uint8 out; /* SO line state */ + uint8 status; /* status register */ + uint8 opcode; /* 8-bit opcode */ + uint8 buffer; /* 8-bit data buffer */ + uint16 addr; /* 16-bit address */ + uint32 cycles; /* current operation cycle */ + T_STATE_SPI state; /* current operation state */ +} T_EEPROM_SPI; + +static T_EEPROM_SPI spi_eeprom; + +void eeprom_spi_init() +{ + /* reset eeprom state */ + memset(&spi_eeprom, 0, sizeof(T_EEPROM_SPI)); + spi_eeprom.out = 1; + spi_eeprom.state = GET_OPCODE; + + /* enable backup RAM */ + sram.custom = 2; + sram.on = 1; +} + +void eeprom_spi_write(unsigned char data) +{ + /* Make sure !HOLD is high */ + if (data & (1 << BIT_HOLD)) + { + /* Check !CS state */ + if (data & (1 << BIT_CS)) + { + /* !CS high -> end of current operation */ + spi_eeprom.cycles = 0; + spi_eeprom.out = 1; + spi_eeprom.opcode = 0; + spi_eeprom.state = GET_OPCODE; + } + else + { + /* !CS low -> process current operation */ + switch (spi_eeprom.state) + { + case GET_OPCODE: + { + /* latch data on CLK positive edge */ + if ((data & (1 << BIT_CLK)) && !spi_eeprom.clk) + { + /* 8-bit opcode buffer */ + spi_eeprom.opcode |= ((data >> BIT_DATA) & 1); + spi_eeprom.cycles++; + + /* last bit ? */ + if (spi_eeprom.cycles == 8) + { + /* reset cycles count */ + spi_eeprom.cycles = 0; + + /* Decode instruction */ + switch (spi_eeprom.opcode) + { + case 0x01: + { + /* WRITE STATUS */ + spi_eeprom.buffer = 0; + spi_eeprom.state = WRITE_BYTE; + break; + } + + case 0x02: + { + /* WRITE BYTE */ + spi_eeprom.addr = 0; + spi_eeprom.state = GET_ADDRESS; + break; + } + + case 0x03: + { + /* READ BYTE */ + spi_eeprom.addr = 0; + spi_eeprom.state = GET_ADDRESS; + break; + } + + case 0x04: + { + /* WRITE DISABLE */ + spi_eeprom.status &= ~0x02; + spi_eeprom.state = STANDBY; + break; + } + + case 0x05: + { + /* READ STATUS */ + spi_eeprom.buffer = spi_eeprom.status; + spi_eeprom.state = READ_BYTE; + break; + } + + case 0x06: + { + /* WRITE ENABLE */ + spi_eeprom.status |= 0x02; + spi_eeprom.state = STANDBY; + break; + } + + default: + { + /* specific instructions (not supported) */ + spi_eeprom.state = STANDBY; + break; + } + } + } + else + { + /* shift opcode value */ + spi_eeprom.opcode = spi_eeprom.opcode << 1; + } + } + break; + } + + case GET_ADDRESS: + { + /* latch data on CLK positive edge */ + if ((data & (1 << BIT_CLK)) && !spi_eeprom.clk) + { + /* 16-bit address */ + spi_eeprom.addr |= ((data >> BIT_DATA) & 1); + spi_eeprom.cycles++; + + /* last bit ? */ + if (spi_eeprom.cycles == 16) + { + /* reset cycles count */ + spi_eeprom.cycles = 0; + + /* mask unused address bits */ + spi_eeprom.addr &= SIZE_MASK; + + /* operation type */ + if (spi_eeprom.opcode & 0x01) + { + /* READ operation */ + spi_eeprom.buffer = sram.sram[spi_eeprom.addr]; + spi_eeprom.state = READ_BYTE; + } + else + { + /* WRITE operation */ + spi_eeprom.buffer = 0; + spi_eeprom.state = WRITE_BYTE; + } + } + else + { + /* shift address value */ + spi_eeprom.addr = spi_eeprom.addr << 1; + } + } + break; + } + + case WRITE_BYTE: + { + /* latch data on CLK positive edge */ + if ((data & (1 << BIT_CLK)) && !spi_eeprom.clk) + { + /* 8-bit data buffer */ + spi_eeprom.buffer |= ((data >> BIT_DATA) & 1); + spi_eeprom.cycles++; + + /* last bit ? */ + if (spi_eeprom.cycles == 8) + { + /* reset cycles count */ + spi_eeprom.cycles = 0; + + /* write data to destination */ + if (spi_eeprom.opcode & 0x01) + { + /* update status register */ + spi_eeprom.status = (spi_eeprom.status & 0x02) | (spi_eeprom.buffer & 0x0c); + + /* wait for operation end */ + spi_eeprom.state = STANDBY; + } + else + { + /* Memory Array (write-protected) */ + if (spi_eeprom.status & 2) + { + /* check array protection bits (BP0, BP1) */ + switch ((spi_eeprom.status >> 2) & 0x03) + { + case 0x01: + { + /* $C000-$FFFF (sector #3) is protected */ + if (spi_eeprom.addr < 0xC000) + { + sram.sram[spi_eeprom.addr] = spi_eeprom.buffer; + } + break; + } + + case 0x02: + { + /* $8000-$FFFF (sectors #2 and #3) is protected */ + if (spi_eeprom.addr < 0x8000) + { + sram.sram[spi_eeprom.addr] = spi_eeprom.buffer; + } + break; + } + + case 0x03: + { + /* $0000-$FFFF (all sectors) is protected */ + break; + } + + default: + { + /* no sectors protected */ + sram.sram[spi_eeprom.addr] = spi_eeprom.buffer; + break; + } + } + } + + /* reset data buffer */ + spi_eeprom.buffer = 0; + + /* increase array address (sequential writes are limited within the same page) */ + spi_eeprom.addr = (spi_eeprom.addr & ~PAGE_MASK) | ((spi_eeprom.addr + 1) & PAGE_MASK); + } + } + else + { + /* shift data buffer value */ + spi_eeprom.buffer = spi_eeprom.buffer << 1; + } + } + break; + } + + case READ_BYTE: + { + /* output data on CLK positive edge */ + if ((data & (1 << BIT_CLK)) && !spi_eeprom.clk) + { + /* read out bits */ + spi_eeprom.out = (spi_eeprom.buffer >> (7 - spi_eeprom.cycles)) & 1; + spi_eeprom.cycles++; + + /* last bit ? */ + if (spi_eeprom.cycles == 8) + { + /* reset cycles count */ + spi_eeprom.cycles = 0; + + /* read from memory array ? */ + if (spi_eeprom.opcode == 0x03) + { + /* read next array byte */ + spi_eeprom.addr = (spi_eeprom.addr + 1) & SIZE_MASK; + spi_eeprom.buffer = sram.sram[spi_eeprom.addr]; + } + } + } + break; + } + + default: + { + /* wait for !CS low->high transition */ + break; + } + } + } + } + + /* update input lines */ + spi_eeprom.cs = (data >> BIT_CS) & 1; + spi_eeprom.clk = (data >> BIT_CLK) & 1; +} + +unsigned int eeprom_spi_read(unsigned int address) +{ + return (spi_eeprom.out << BIT_DATA); +} + diff --git a/pico/carthw/eeprom_spi.h b/pico/carthw/eeprom_spi.h new file mode 100644 index 00000000..1001e6e8 --- /dev/null +++ b/pico/carthw/eeprom_spi.h @@ -0,0 +1,47 @@ +/**************************************************************************** + * Genesis Plus + * SPI Serial EEPROM (25XX512 only) support + * + * Copyright (C) 2012 Eke-Eke (Genesis Plus GX) + * + * Redistribution and use of this code or any derivative works are permitted + * provided that the following conditions are met: + * + * - Redistributions may not be sold, nor may they be used in a commercial + * product or activity. + * + * - Redistributions that are modified from the original source must include the + * complete source code, including the source code for all components used by a + * binary built from the modified sources. However, as a special exception, the + * source code distributed need not include anything that is normally distributed + * (in either source or binary form) with the major components (compiler, kernel, + * and so on) of the operating system on which the executable runs, unless that + * component itself accompanies the executable. + * + * - Redistributions 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. + * + * 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. + * + ****************************************************************************************/ + +#ifndef _EEPROM_SPI_H_ +#define _EEPROM_SPI_H_ + +/* Function prototypes */ +extern void eeprom_spi_init(); +extern void eeprom_spi_write(unsigned char data); +extern unsigned int eeprom_spi_read(unsigned int address); + +#endif