1 /*
2  * Interface for the 93C66/56/46/26/06 serial eeprom parts.
3  *
4  * Copyright (c) 1995, 1996 Daniel M. Eischen
5  * All rights reserved.
6  *
7  * Redistribution and use in source and binary forms, with or without
8  * modification, are permitted provided that the following conditions
9  * are met:
10  * 1. Redistributions of source code must retain the above copyright
11  *    notice, this list of conditions, and the following disclaimer,
12  *    without modification.
13  * 2. The name of the author may not be used to endorse or promote products
14  *    derived from this software without specific prior written permission.
15  *
16  * Alternatively, this software may be distributed under the terms of the
17  * GNU General Public License ("GPL").
18  *
19  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
20  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
21  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
22  * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE FOR
23  * ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
24  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
25  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
26  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
27  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
28  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
29  * SUCH DAMAGE.
30  *
31  * $Id: //depot/aic7xxx/aic7xxx/aic7xxx_93cx6.c#19 $
32  */
33 
34 /*
35  *   The instruction set of the 93C66/56/46/26/06 chips are as follows:
36  *
37  *               Start  OP	    *
38  *     Function   Bit  Code  Address**  Data     Description
39  *     -------------------------------------------------------------------
40  *     READ        1    10   A5 - A0             Reads data stored in memory,
41  *                                               starting at specified address
42  *     EWEN        1    00   11XXXX              Write enable must precede
43  *                                               all programming modes
44  *     ERASE       1    11   A5 - A0             Erase register A5A4A3A2A1A0
45  *     WRITE       1    01   A5 - A0   D15 - D0  Writes register
46  *     ERAL        1    00   10XXXX              Erase all registers
47  *     WRAL        1    00   01XXXX    D15 - D0  Writes to all registers
48  *     EWDS        1    00   00XXXX              Disables all programming
49  *                                               instructions
50  *     *Note: A value of X for address is a don't care condition.
51  *    **Note: There are 8 address bits for the 93C56/66 chips unlike
52  *	      the 93C46/26/06 chips which have 6 address bits.
53  *
54  *   The 93C46 has a four wire interface: clock, chip select, data in, and
55  *   data out.  In order to perform one of the above functions, you need
56  *   to enable the chip select for a clock period (typically a minimum of
57  *   1 usec, with the clock high and low a minimum of 750 and 250 nsec
58  *   respectively).  While the chip select remains high, you can clock in
59  *   the instructions (above) starting with the start bit, followed by the
60  *   OP code, Address, and Data (if needed).  For the READ instruction, the
61  *   requested 16-bit register contents is read from the data out line but
62  *   is preceded by an initial zero (leading 0, followed by 16-bits, MSB
63  *   first).  The clock cycling from low to high initiates the next data
64  *   bit to be sent from the chip.
65  */
66 
67 #include "aic7xxx_osm.h"
68 #include "aic7xxx_inline.h"
69 #include "aic7xxx_93cx6.h"
70 
71 /*
72  * Right now, we only have to read the SEEPROM.  But we make it easier to
73  * add other 93Cx6 functions.
74  */
75 struct seeprom_cmd {
76 	uint8_t len;
77 	uint8_t bits[11];
78 };
79 
80 /* Short opcodes for the c46 */
81 static const struct seeprom_cmd seeprom_ewen = {9, {1, 0, 0, 1, 1, 0, 0, 0, 0}};
82 static const struct seeprom_cmd seeprom_ewds = {9, {1, 0, 0, 0, 0, 0, 0, 0, 0}};
83 
84 /* Long opcodes for the C56/C66 */
85 static const struct seeprom_cmd seeprom_long_ewen = {11, {1, 0, 0, 1, 1, 0, 0, 0, 0}};
86 static const struct seeprom_cmd seeprom_long_ewds = {11, {1, 0, 0, 0, 0, 0, 0, 0, 0}};
87 
88 /* Common opcodes */
89 static const struct seeprom_cmd seeprom_write = {3, {1, 0, 1}};
90 static const struct seeprom_cmd seeprom_read  = {3, {1, 1, 0}};
91 
92 /*
93  * Wait for the SEERDY to go high; about 800 ns.
94  */
95 #define CLOCK_PULSE(sd, rdy)				\
96 	while ((SEEPROM_STATUS_INB(sd) & rdy) == 0) {	\
97 		;  /* Do nothing */			\
98 	}						\
99 	(void)SEEPROM_INB(sd);	/* Clear clock */
100 
101 /*
102  * Send a START condition and the given command
103  */
104 static void
105 send_seeprom_cmd(struct seeprom_descriptor *sd, const struct seeprom_cmd *cmd)
106 {
107 	uint8_t temp;
108 	int i = 0;
109 
110 	/* Send chip select for one clock cycle. */
111 	temp = sd->sd_MS ^ sd->sd_CS;
112 	SEEPROM_OUTB(sd, temp ^ sd->sd_CK);
113 	CLOCK_PULSE(sd, sd->sd_RDY);
114 
115 	for (i = 0; i < cmd->len; i++) {
116 		if (cmd->bits[i] != 0)
117 			temp ^= sd->sd_DO;
118 		SEEPROM_OUTB(sd, temp);
119 		CLOCK_PULSE(sd, sd->sd_RDY);
120 		SEEPROM_OUTB(sd, temp ^ sd->sd_CK);
121 		CLOCK_PULSE(sd, sd->sd_RDY);
122 		if (cmd->bits[i] != 0)
123 			temp ^= sd->sd_DO;
124 	}
125 }
126 
127 /*
128  * Clear CS put the chip in the reset state, where it can wait for new commands.
129  */
130 static void
131 reset_seeprom(struct seeprom_descriptor *sd)
132 {
133 	uint8_t temp;
134 
135 	temp = sd->sd_MS;
136 	SEEPROM_OUTB(sd, temp);
137 	CLOCK_PULSE(sd, sd->sd_RDY);
138 	SEEPROM_OUTB(sd, temp ^ sd->sd_CK);
139 	CLOCK_PULSE(sd, sd->sd_RDY);
140 	SEEPROM_OUTB(sd, temp);
141 	CLOCK_PULSE(sd, sd->sd_RDY);
142 }
143 
144 /*
145  * Read the serial EEPROM and returns 1 if successful and 0 if
146  * not successful.
147  */
148 int
149 ahc_read_seeprom(struct seeprom_descriptor *sd, uint16_t *buf,
150 		 u_int start_addr, u_int count)
151 {
152 	int i = 0;
153 	u_int k = 0;
154 	uint16_t v;
155 	uint8_t temp;
156 
157 	/*
158 	 * Read the requested registers of the seeprom.  The loop
159 	 * will range from 0 to count-1.
160 	 */
161 	for (k = start_addr; k < count + start_addr; k++) {
162 		/*
163 		 * Now we're ready to send the read command followed by the
164 		 * address of the 16-bit register we want to read.
165 		 */
166 		send_seeprom_cmd(sd, &seeprom_read);
167 
168 		/* Send the 6 or 8 bit address (MSB first, LSB last). */
169 		temp = sd->sd_MS ^ sd->sd_CS;
170 		for (i = (sd->sd_chip - 1); i >= 0; i--) {
171 			if ((k & (1 << i)) != 0)
172 				temp ^= sd->sd_DO;
173 			SEEPROM_OUTB(sd, temp);
174 			CLOCK_PULSE(sd, sd->sd_RDY);
175 			SEEPROM_OUTB(sd, temp ^ sd->sd_CK);
176 			CLOCK_PULSE(sd, sd->sd_RDY);
177 			if ((k & (1 << i)) != 0)
178 				temp ^= sd->sd_DO;
179 		}
180 
181 		/*
182 		 * Now read the 16 bit register.  An initial 0 precedes the
183 		 * register contents which begins with bit 15 (MSB) and ends
184 		 * with bit 0 (LSB).  The initial 0 will be shifted off the
185 		 * top of our word as we let the loop run from 0 to 16.
186 		 */
187 		v = 0;
188 		for (i = 16; i >= 0; i--) {
189 			SEEPROM_OUTB(sd, temp);
190 			CLOCK_PULSE(sd, sd->sd_RDY);
191 			v <<= 1;
192 			if (SEEPROM_DATA_INB(sd) & sd->sd_DI)
193 				v |= 1;
194 			SEEPROM_OUTB(sd, temp ^ sd->sd_CK);
195 			CLOCK_PULSE(sd, sd->sd_RDY);
196 		}
197 
198 		buf[k - start_addr] = v;
199 
200 		/* Reset the chip select for the next command cycle. */
201 		reset_seeprom(sd);
202 	}
203 #ifdef AHC_DUMP_EEPROM
204 	printk("\nSerial EEPROM:\n\t");
205 	for (k = 0; k < count; k = k + 1) {
206 		if (((k % 8) == 0) && (k != 0)) {
207 			printk(KERN_CONT "\n\t");
208 		}
209 		printk(KERN_CONT " 0x%x", buf[k]);
210 	}
211 	printk(KERN_CONT "\n");
212 #endif
213 	return (1);
214 }
215 
216 /*
217  * Write the serial EEPROM and return 1 if successful and 0 if
218  * not successful.
219  */
220 int
221 ahc_write_seeprom(struct seeprom_descriptor *sd, uint16_t *buf,
222 		  u_int start_addr, u_int count)
223 {
224 	const struct seeprom_cmd *ewen, *ewds;
225 	uint16_t v;
226 	uint8_t temp;
227 	int i, k;
228 
229 	/* Place the chip into write-enable mode */
230 	if (sd->sd_chip == C46) {
231 		ewen = &seeprom_ewen;
232 		ewds = &seeprom_ewds;
233 	} else if (sd->sd_chip == C56_66) {
234 		ewen = &seeprom_long_ewen;
235 		ewds = &seeprom_long_ewds;
236 	} else {
237 		printk("ahc_write_seeprom: unsupported seeprom type %d\n",
238 		       sd->sd_chip);
239 		return (0);
240 	}
241 
242 	send_seeprom_cmd(sd, ewen);
243 	reset_seeprom(sd);
244 
245 	/* Write all requested data out to the seeprom. */
246 	temp = sd->sd_MS ^ sd->sd_CS;
247 	for (k = start_addr; k < count + start_addr; k++) {
248 		/* Send the write command */
249 		send_seeprom_cmd(sd, &seeprom_write);
250 
251 		/* Send the 6 or 8 bit address (MSB first). */
252 		for (i = (sd->sd_chip - 1); i >= 0; i--) {
253 			if ((k & (1 << i)) != 0)
254 				temp ^= sd->sd_DO;
255 			SEEPROM_OUTB(sd, temp);
256 			CLOCK_PULSE(sd, sd->sd_RDY);
257 			SEEPROM_OUTB(sd, temp ^ sd->sd_CK);
258 			CLOCK_PULSE(sd, sd->sd_RDY);
259 			if ((k & (1 << i)) != 0)
260 				temp ^= sd->sd_DO;
261 		}
262 
263 		/* Write the 16 bit value, MSB first */
264 		v = buf[k - start_addr];
265 		for (i = 15; i >= 0; i--) {
266 			if ((v & (1 << i)) != 0)
267 				temp ^= sd->sd_DO;
268 			SEEPROM_OUTB(sd, temp);
269 			CLOCK_PULSE(sd, sd->sd_RDY);
270 			SEEPROM_OUTB(sd, temp ^ sd->sd_CK);
271 			CLOCK_PULSE(sd, sd->sd_RDY);
272 			if ((v & (1 << i)) != 0)
273 				temp ^= sd->sd_DO;
274 		}
275 
276 		/* Wait for the chip to complete the write */
277 		temp = sd->sd_MS;
278 		SEEPROM_OUTB(sd, temp);
279 		CLOCK_PULSE(sd, sd->sd_RDY);
280 		temp = sd->sd_MS ^ sd->sd_CS;
281 		do {
282 			SEEPROM_OUTB(sd, temp);
283 			CLOCK_PULSE(sd, sd->sd_RDY);
284 			SEEPROM_OUTB(sd, temp ^ sd->sd_CK);
285 			CLOCK_PULSE(sd, sd->sd_RDY);
286 		} while ((SEEPROM_DATA_INB(sd) & sd->sd_DI) == 0);
287 
288 		reset_seeprom(sd);
289 	}
290 
291 	/* Put the chip back into write-protect mode */
292 	send_seeprom_cmd(sd, ewds);
293 	reset_seeprom(sd);
294 
295 	return (1);
296 }
297 
298 int
299 ahc_verify_cksum(struct seeprom_config *sc)
300 {
301 	int i;
302 	int maxaddr;
303 	uint32_t checksum;
304 	uint16_t *scarray;
305 
306 	maxaddr = (sizeof(*sc)/2) - 1;
307 	checksum = 0;
308 	scarray = (uint16_t *)sc;
309 
310 	for (i = 0; i < maxaddr; i++)
311 		checksum = checksum + scarray[i];
312 	if (checksum == 0
313 	 || (checksum & 0xFFFF) != sc->checksum) {
314 		return (0);
315 	} else {
316 		return(1);
317 	}
318 }
319