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/* $OpenBSD: smc93cx6.c,v 1.16 2003/08/15 23:41:47 fgsch Exp $ */
/* $FreeBSD: sys/dev/aic7xxx/93cx6.c,v 1.5 2000/01/07 23:08:17 gibbs Exp $ */
/*
* Interface for the 93C66/56/46/26/06 serial eeprom parts.
*
* Copyright (c) 1995, 1996 Daniel M. Eischen
* All rights reserved.
*
* 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 immediately at the beginning of the file, without modification,
* 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. Absolutely no warranty of function or purpose is made by the author
* Daniel M. Eischen.
* 4. Modifications may be freely made to this file if the above conditions
* are met.
*/
/*
* The instruction set of the 93C66/56/46/26/06 chips are as follows:
*
* Start OP *
* Function Bit Code Address** Data Description
* -------------------------------------------------------------------
* READ 1 10 A5 - A0 Reads data stored in memory,
* starting at specified address
* EWEN 1 00 11XXXX Write enable must precede
* all programming modes
* ERASE 1 11 A5 - A0 Erase register A5A4A3A2A1A0
* WRITE 1 01 A5 - A0 D15 - D0 Writes register
* ERAL 1 00 10XXXX Erase all registers
* WRAL 1 00 01XXXX D15 - D0 Writes to all registers
* EWDS 1 00 00XXXX Disables all programming
* instructions
* *Note: A value of X for address is a don't care condition.
* **Note: There are 8 address bits for the 93C56/66 chips unlike
* the 93C46/26/06 chips which have 6 address bits.
*
* The 93C46 has a four wire interface: clock, chip select, data in, and
* data out. In order to perform one of the above functions, you need
* to enable the chip select for a clock period (typically a minimum of
* 1 usec, with the clock high and low a minimum of 750 and 250 nsec
* respectively). While the chip select remains high, you can clock in
* the instructions (above) starting with the start bit, followed by the
* OP code, Address, and Data (if needed). For the READ instruction, the
* requested 16-bit register contents is read from the data out line but
* is preceded by an initial zero (leading 0, followed by 16-bits, MSB
* first). The clock cycling from low to high initiates the next data
* bit to be sent from the chip.
*
*/
#include <sys/param.h>
#include <sys/systm.h>
#include <machine/bus.h>
#include <dev/ic/smc93cx6var.h>
/*
* Right now, we only have to read the SEEPROM. But we make it easier to
* add other 93Cx6 functions.
*/
static struct seeprom_cmd {
unsigned char len;
unsigned char bits[9];
} seeprom_read = {3, {1, 1, 0}};
/*
* Wait for the SEERDY to go high; about 800 ns.
*/
#define CLOCK_PULSE(sd, rdy) \
while ((SEEPROM_STATUS_INB(sd) & rdy) == 0) { \
; /* Do nothing */ \
} \
(void)SEEPROM_INB(sd); /* Clear clock */
/*
* Send a START condition and the given command
*/
static void
send_seeprom_cmd(struct seeprom_descriptor *sd, struct seeprom_cmd *cmd)
{
u_int8_t temp;
int i = 0;
/* Send chip select for one clock cycle. */
temp = sd->sd_MS ^ sd->sd_CS;
SEEPROM_OUTB(sd, temp ^ sd->sd_CK);
CLOCK_PULSE(sd, sd->sd_RDY);
for (i = 0; i < cmd->len; i++) {
if (cmd->bits[i] != 0)
temp ^= sd->sd_DO;
SEEPROM_OUTB(sd, temp);
CLOCK_PULSE(sd, sd->sd_RDY);
SEEPROM_OUTB(sd, temp ^ sd->sd_CK);
CLOCK_PULSE(sd, sd->sd_RDY);
if (cmd->bits[i] != 0)
temp ^= sd->sd_DO;
}
}
/*
* Clear CS put the chip in the reset state, where it can wait for new commands.
*/
static void
reset_seeprom(struct seeprom_descriptor *sd)
{
u_int8_t temp;
temp = sd->sd_MS;
SEEPROM_OUTB(sd, temp);
CLOCK_PULSE(sd, sd->sd_RDY);
SEEPROM_OUTB(sd, temp ^ sd->sd_CK);
CLOCK_PULSE(sd, sd->sd_RDY);
SEEPROM_OUTB(sd, temp);
CLOCK_PULSE(sd, sd->sd_RDY);
}
/*
* Read the serial EEPROM and returns 1 if successful and 0 if
* not successful.
*/
int
read_seeprom(sd, buf, start_addr, count)
struct seeprom_descriptor *sd;
u_int16_t *buf;
bus_size_t start_addr;
bus_size_t count;
{
int i = 0;
u_int k = 0;
u_int16_t v;
u_int8_t temp;
/*
* Read the requested registers of the seeprom. The loop
* will range from 0 to count-1.
*/
for (k = start_addr; k < count + start_addr; k++) {
/*
* Now we're ready to send the read command followed by the
* address of the 16-bit register we want to read.
*/
send_seeprom_cmd(sd, &seeprom_read);
/* Send the 6 or 8 bit address (MSB first, LSB last). */
temp = sd->sd_MS ^ sd->sd_CS;
for (i = (sd->sd_chip - 1); i >= 0; i--) {
if ((k & (1 << i)) != 0)
temp ^= sd->sd_DO;
SEEPROM_OUTB(sd, temp);
CLOCK_PULSE(sd, sd->sd_RDY);
SEEPROM_OUTB(sd, temp ^ sd->sd_CK);
CLOCK_PULSE(sd, sd->sd_RDY);
if ((k & (1 << i)) != 0)
temp ^= sd->sd_DO;
}
/*
* Now read the 16 bit register. An initial 0 precedes the
* register contents which begins with bit 15 (MSB) and ends
* with bit 0 (LSB). The initial 0 will be shifted off the
* top of our word as we let the loop run from 0 to 16.
*/
v = 0;
for (i = 16; i >= 0; i--) {
SEEPROM_OUTB(sd, temp);
CLOCK_PULSE(sd, sd->sd_RDY);
v <<= 1;
if (SEEPROM_DATA_INB(sd) & sd->sd_DI)
v |= 1;
SEEPROM_OUTB(sd, temp ^ sd->sd_CK);
CLOCK_PULSE(sd, sd->sd_RDY);
}
buf[k - start_addr] = v;
/* Reset the chip select for the next command cycle. */
reset_seeprom(sd);
}
#ifdef AHC_DUMP_EEPROM
printf("\nSerial EEPROM:\n\t");
for (k = 0; k < count; k = k + 1) {
if (((k % 8) == 0) && (k != 0)) {
printf ("\n\t");
}
printf (" 0x%x", buf[k]);
}
printf ("\n");
#endif
return (1);
}
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