1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3 * Copyright (C) 2004 - 2006 rt2x00 SourceForge Project
4 * <http://rt2x00.serialmonkey.com>
5 *
6 * Module: eeprom_93cx6
7 * Abstract: EEPROM reader routines for 93cx6 chipsets.
8 * Supported chipsets: 93c46 & 93c66.
9 */
10
11 #include <linux/kernel.h>
12 #include <linux/module.h>
13 #include <linux/delay.h>
14 #include <linux/eeprom_93cx6.h>
15
16 MODULE_AUTHOR("http://rt2x00.serialmonkey.com");
17 MODULE_VERSION("1.0");
18 MODULE_DESCRIPTION("EEPROM 93cx6 chip driver");
19 MODULE_LICENSE("GPL");
20
eeprom_93cx6_pulse_high(struct eeprom_93cx6 * eeprom)21 static inline void eeprom_93cx6_pulse_high(struct eeprom_93cx6 *eeprom)
22 {
23 eeprom->reg_data_clock = 1;
24 eeprom->register_write(eeprom);
25
26 /*
27 * Add a short delay for the pulse to work.
28 * According to the specifications the "maximum minimum"
29 * time should be 450ns.
30 */
31 ndelay(450);
32 }
33
eeprom_93cx6_pulse_low(struct eeprom_93cx6 * eeprom)34 static inline void eeprom_93cx6_pulse_low(struct eeprom_93cx6 *eeprom)
35 {
36 eeprom->reg_data_clock = 0;
37 eeprom->register_write(eeprom);
38
39 /*
40 * Add a short delay for the pulse to work.
41 * According to the specifications the "maximum minimum"
42 * time should be 450ns.
43 */
44 ndelay(450);
45 }
46
eeprom_93cx6_startup(struct eeprom_93cx6 * eeprom)47 static void eeprom_93cx6_startup(struct eeprom_93cx6 *eeprom)
48 {
49 /*
50 * Clear all flags, and enable chip select.
51 */
52 eeprom->register_read(eeprom);
53 eeprom->reg_data_in = 0;
54 eeprom->reg_data_out = 0;
55 eeprom->reg_data_clock = 0;
56 eeprom->reg_chip_select = 1;
57 eeprom->drive_data = 1;
58 eeprom->register_write(eeprom);
59
60 /*
61 * kick a pulse.
62 */
63 eeprom_93cx6_pulse_high(eeprom);
64 eeprom_93cx6_pulse_low(eeprom);
65 }
66
eeprom_93cx6_cleanup(struct eeprom_93cx6 * eeprom)67 static void eeprom_93cx6_cleanup(struct eeprom_93cx6 *eeprom)
68 {
69 /*
70 * Clear chip_select and data_in flags.
71 */
72 eeprom->register_read(eeprom);
73 eeprom->reg_data_in = 0;
74 eeprom->reg_chip_select = 0;
75 eeprom->register_write(eeprom);
76
77 /*
78 * kick a pulse.
79 */
80 eeprom_93cx6_pulse_high(eeprom);
81 eeprom_93cx6_pulse_low(eeprom);
82 }
83
eeprom_93cx6_write_bits(struct eeprom_93cx6 * eeprom,const u16 data,const u16 count)84 static void eeprom_93cx6_write_bits(struct eeprom_93cx6 *eeprom,
85 const u16 data, const u16 count)
86 {
87 unsigned int i;
88
89 eeprom->register_read(eeprom);
90
91 /*
92 * Clear data flags.
93 */
94 eeprom->reg_data_in = 0;
95 eeprom->reg_data_out = 0;
96 eeprom->drive_data = 1;
97
98 /*
99 * Start writing all bits.
100 */
101 for (i = count; i > 0; i--) {
102 /*
103 * Check if this bit needs to be set.
104 */
105 eeprom->reg_data_in = !!(data & (1 << (i - 1)));
106
107 /*
108 * Write the bit to the eeprom register.
109 */
110 eeprom->register_write(eeprom);
111
112 /*
113 * Kick a pulse.
114 */
115 eeprom_93cx6_pulse_high(eeprom);
116 eeprom_93cx6_pulse_low(eeprom);
117 }
118
119 eeprom->reg_data_in = 0;
120 eeprom->register_write(eeprom);
121 }
122
eeprom_93cx6_read_bits(struct eeprom_93cx6 * eeprom,u16 * data,const u16 count)123 static void eeprom_93cx6_read_bits(struct eeprom_93cx6 *eeprom,
124 u16 *data, const u16 count)
125 {
126 unsigned int i;
127 u16 buf = 0;
128
129 eeprom->register_read(eeprom);
130
131 /*
132 * Clear data flags.
133 */
134 eeprom->reg_data_in = 0;
135 eeprom->reg_data_out = 0;
136 eeprom->drive_data = 0;
137
138 /*
139 * Start reading all bits.
140 */
141 for (i = count; i > 0; i--) {
142 eeprom_93cx6_pulse_high(eeprom);
143
144 eeprom->register_read(eeprom);
145
146 /*
147 * Clear data_in flag.
148 */
149 eeprom->reg_data_in = 0;
150
151 /*
152 * Read if the bit has been set.
153 */
154 if (eeprom->reg_data_out)
155 buf |= (1 << (i - 1));
156
157 eeprom_93cx6_pulse_low(eeprom);
158 }
159
160 *data = buf;
161 }
162
163 /**
164 * eeprom_93cx6_read - Read a word from eeprom
165 * @eeprom: Pointer to eeprom structure
166 * @word: Word index from where we should start reading
167 * @data: target pointer where the information will have to be stored
168 *
169 * This function will read the eeprom data as host-endian word
170 * into the given data pointer.
171 */
eeprom_93cx6_read(struct eeprom_93cx6 * eeprom,const u8 word,u16 * data)172 void eeprom_93cx6_read(struct eeprom_93cx6 *eeprom, const u8 word,
173 u16 *data)
174 {
175 u16 command;
176
177 /*
178 * Initialize the eeprom register
179 */
180 eeprom_93cx6_startup(eeprom);
181
182 /*
183 * Select the read opcode and the word to be read.
184 */
185 command = (PCI_EEPROM_READ_OPCODE << eeprom->width) | word;
186 eeprom_93cx6_write_bits(eeprom, command,
187 PCI_EEPROM_WIDTH_OPCODE + eeprom->width);
188
189 /*
190 * Read the requested 16 bits.
191 */
192 eeprom_93cx6_read_bits(eeprom, data, 16);
193
194 /*
195 * Cleanup eeprom register.
196 */
197 eeprom_93cx6_cleanup(eeprom);
198 }
199 EXPORT_SYMBOL_GPL(eeprom_93cx6_read);
200
201 /**
202 * eeprom_93cx6_multiread - Read multiple words from eeprom
203 * @eeprom: Pointer to eeprom structure
204 * @word: Word index from where we should start reading
205 * @data: target pointer where the information will have to be stored
206 * @words: Number of words that should be read.
207 *
208 * This function will read all requested words from the eeprom,
209 * this is done by calling eeprom_93cx6_read() multiple times.
210 * But with the additional change that while the eeprom_93cx6_read
211 * will return host ordered bytes, this method will return little
212 * endian words.
213 */
eeprom_93cx6_multiread(struct eeprom_93cx6 * eeprom,const u8 word,__le16 * data,const u16 words)214 void eeprom_93cx6_multiread(struct eeprom_93cx6 *eeprom, const u8 word,
215 __le16 *data, const u16 words)
216 {
217 unsigned int i;
218 u16 tmp;
219
220 for (i = 0; i < words; i++) {
221 tmp = 0;
222 eeprom_93cx6_read(eeprom, word + i, &tmp);
223 data[i] = cpu_to_le16(tmp);
224 }
225 }
226 EXPORT_SYMBOL_GPL(eeprom_93cx6_multiread);
227
228 /**
229 * eeprom_93cx6_readb - Read a byte from eeprom
230 * @eeprom: Pointer to eeprom structure
231 * @byte: Byte index from where we should start reading
232 * @data: target pointer where the information will have to be stored
233 *
234 * This function will read a byte of the eeprom data
235 * into the given data pointer.
236 */
eeprom_93cx6_readb(struct eeprom_93cx6 * eeprom,const u8 byte,u8 * data)237 void eeprom_93cx6_readb(struct eeprom_93cx6 *eeprom, const u8 byte,
238 u8 *data)
239 {
240 u16 command;
241 u16 tmp;
242
243 /*
244 * Initialize the eeprom register
245 */
246 eeprom_93cx6_startup(eeprom);
247
248 /*
249 * Select the read opcode and the byte to be read.
250 */
251 command = (PCI_EEPROM_READ_OPCODE << (eeprom->width + 1)) | byte;
252 eeprom_93cx6_write_bits(eeprom, command,
253 PCI_EEPROM_WIDTH_OPCODE + eeprom->width + 1);
254
255 /*
256 * Read the requested 8 bits.
257 */
258 eeprom_93cx6_read_bits(eeprom, &tmp, 8);
259 *data = tmp & 0xff;
260
261 /*
262 * Cleanup eeprom register.
263 */
264 eeprom_93cx6_cleanup(eeprom);
265 }
266 EXPORT_SYMBOL_GPL(eeprom_93cx6_readb);
267
268 /**
269 * eeprom_93cx6_multireadb - Read multiple bytes from eeprom
270 * @eeprom: Pointer to eeprom structure
271 * @byte: Index from where we should start reading
272 * @data: target pointer where the information will have to be stored
273 * @bytes: Number of bytes that should be read.
274 *
275 * This function will read all requested bytes from the eeprom,
276 * this is done by calling eeprom_93cx6_readb() multiple times.
277 */
eeprom_93cx6_multireadb(struct eeprom_93cx6 * eeprom,const u8 byte,u8 * data,const u16 bytes)278 void eeprom_93cx6_multireadb(struct eeprom_93cx6 *eeprom, const u8 byte,
279 u8 *data, const u16 bytes)
280 {
281 unsigned int i;
282
283 for (i = 0; i < bytes; i++)
284 eeprom_93cx6_readb(eeprom, byte + i, &data[i]);
285 }
286 EXPORT_SYMBOL_GPL(eeprom_93cx6_multireadb);
287
288 /**
289 * eeprom_93cx6_wren - set the write enable state
290 * @eeprom: Pointer to eeprom structure
291 * @enable: true to enable writes, otherwise disable writes
292 *
293 * Set the EEPROM write enable state to either allow or deny
294 * writes depending on the @enable value.
295 */
eeprom_93cx6_wren(struct eeprom_93cx6 * eeprom,bool enable)296 void eeprom_93cx6_wren(struct eeprom_93cx6 *eeprom, bool enable)
297 {
298 u16 command;
299
300 /* start the command */
301 eeprom_93cx6_startup(eeprom);
302
303 /* create command to enable/disable */
304
305 command = enable ? PCI_EEPROM_EWEN_OPCODE : PCI_EEPROM_EWDS_OPCODE;
306 command <<= (eeprom->width - 2);
307
308 eeprom_93cx6_write_bits(eeprom, command,
309 PCI_EEPROM_WIDTH_OPCODE + eeprom->width);
310
311 eeprom_93cx6_cleanup(eeprom);
312 }
313 EXPORT_SYMBOL_GPL(eeprom_93cx6_wren);
314
315 /**
316 * eeprom_93cx6_write - write data to the EEPROM
317 * @eeprom: Pointer to eeprom structure
318 * @addr: Address to write data to.
319 * @data: The data to write to address @addr.
320 *
321 * Write the @data to the specified @addr in the EEPROM and
322 * waiting for the device to finish writing.
323 *
324 * Note, since we do not expect large number of write operations
325 * we delay in between parts of the operation to avoid using excessive
326 * amounts of CPU time busy waiting.
327 */
eeprom_93cx6_write(struct eeprom_93cx6 * eeprom,u8 addr,u16 data)328 void eeprom_93cx6_write(struct eeprom_93cx6 *eeprom, u8 addr, u16 data)
329 {
330 int timeout = 100;
331 u16 command;
332
333 /* start the command */
334 eeprom_93cx6_startup(eeprom);
335
336 command = PCI_EEPROM_WRITE_OPCODE << eeprom->width;
337 command |= addr;
338
339 /* send write command */
340 eeprom_93cx6_write_bits(eeprom, command,
341 PCI_EEPROM_WIDTH_OPCODE + eeprom->width);
342
343 /* send data */
344 eeprom_93cx6_write_bits(eeprom, data, 16);
345
346 /* get ready to check for busy */
347 eeprom->drive_data = 0;
348 eeprom->reg_chip_select = 1;
349 eeprom->register_write(eeprom);
350
351 /* wait at-least 250ns to get DO to be the busy signal */
352 usleep_range(1000, 2000);
353
354 /* wait for DO to go high to signify finish */
355
356 while (true) {
357 eeprom->register_read(eeprom);
358
359 if (eeprom->reg_data_out)
360 break;
361
362 usleep_range(1000, 2000);
363
364 if (--timeout <= 0) {
365 printk(KERN_ERR "%s: timeout\n", __func__);
366 break;
367 }
368 }
369
370 eeprom_93cx6_cleanup(eeprom);
371 }
372 EXPORT_SYMBOL_GPL(eeprom_93cx6_write);
373