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/bits.h>
12#include <linux/kernel.h>
13#include <linux/module.h>
14#include <linux/delay.h>
15#include <linux/eeprom_93cx6.h>
16
17MODULE_AUTHOR("http://rt2x00.serialmonkey.com");
18MODULE_VERSION("1.0");
19MODULE_DESCRIPTION("EEPROM 93cx6 chip driver");
20MODULE_LICENSE("GPL");
21
22static inline void eeprom_93cx6_pulse_high(struct eeprom_93cx6 *eeprom)
23{
24 eeprom->reg_data_clock = 1;
25 eeprom->register_write(eeprom);
26
27 /*
28 * Add a short delay for the pulse to work.
29 * According to the specifications the "maximum minimum"
30 * time should be 450ns.
31 */
32 ndelay(450);
33}
34
35static inline void eeprom_93cx6_pulse_low(struct eeprom_93cx6 *eeprom)
36{
37 eeprom->reg_data_clock = 0;
38 eeprom->register_write(eeprom);
39
40 /*
41 * Add a short delay for the pulse to work.
42 * According to the specifications the "maximum minimum"
43 * time should be 450ns.
44 */
45 ndelay(450);
46}
47
48static void eeprom_93cx6_startup(struct eeprom_93cx6 *eeprom)
49{
50 /*
51 * Clear all flags, and enable chip select.
52 */
53 eeprom->register_read(eeprom);
54 eeprom->reg_data_in = 0;
55 eeprom->reg_data_out = 0;
56 eeprom->reg_data_clock = 0;
57 eeprom->reg_chip_select = 1;
58 eeprom->drive_data = 1;
59 eeprom->register_write(eeprom);
60
61 /*
62 * kick a pulse.
63 */
64 eeprom_93cx6_pulse_high(eeprom);
65 eeprom_93cx6_pulse_low(eeprom);
66}
67
68static void eeprom_93cx6_cleanup(struct eeprom_93cx6 *eeprom)
69{
70 /*
71 * Clear chip_select and data_in flags.
72 */
73 eeprom->register_read(eeprom);
74 eeprom->reg_data_in = 0;
75 eeprom->reg_chip_select = 0;
76 eeprom->register_write(eeprom);
77
78 /*
79 * kick a pulse.
80 */
81 eeprom_93cx6_pulse_high(eeprom);
82 eeprom_93cx6_pulse_low(eeprom);
83}
84
85static void eeprom_93cx6_write_bits(struct eeprom_93cx6 *eeprom,
86 const u16 data, const u16 count)
87{
88 unsigned int i;
89
90 eeprom->register_read(eeprom);
91
92 /*
93 * Clear data flags.
94 */
95 eeprom->reg_data_in = 0;
96 eeprom->reg_data_out = 0;
97 eeprom->drive_data = 1;
98
99 /*
100 * Start writing all bits.
101 */
102 for (i = count; i > 0; i--) {
103 /*
104 * Check if this bit needs to be set.
105 */
106 eeprom->reg_data_in = !!(data & BIT(i - 1));
107
108 /*
109 * Write the bit to the eeprom register.
110 */
111 eeprom->register_write(eeprom);
112
113 /*
114 * Kick a pulse.
115 */
116 eeprom_93cx6_pulse_high(eeprom);
117 eeprom_93cx6_pulse_low(eeprom);
118 }
119
120 eeprom->reg_data_in = 0;
121 eeprom->register_write(eeprom);
122}
123
124static void eeprom_93cx6_read_bits(struct eeprom_93cx6 *eeprom,
125 u16 *data, const u16 count)
126{
127 unsigned int i;
128 u16 buf = 0;
129
130 eeprom->register_read(eeprom);
131
132 /*
133 * Clear data flags.
134 */
135 eeprom->reg_data_in = 0;
136 eeprom->reg_data_out = 0;
137 eeprom->drive_data = 0;
138
139 /*
140 * Start reading all bits.
141 */
142 for (i = count; i > 0; i--) {
143 eeprom_93cx6_pulse_high(eeprom);
144
145 eeprom->register_read(eeprom);
146
147 /*
148 * Clear data_in flag.
149 */
150 eeprom->reg_data_in = 0;
151
152 /*
153 * Read if the bit has been set.
154 */
155 if (eeprom->reg_data_out)
156 buf |= BIT(i - 1);
157
158 eeprom_93cx6_pulse_low(eeprom);
159 }
160
161 *data = buf;
162}
163
164/**
165 * eeprom_93cx6_read - Read a word from eeprom
166 * @eeprom: Pointer to eeprom structure
167 * @word: Word index from where we should start reading
168 * @data: target pointer where the information will have to be stored
169 *
170 * This function will read the eeprom data as host-endian word
171 * into the given data pointer.
172 */
173void eeprom_93cx6_read(struct eeprom_93cx6 *eeprom, const u8 word,
174 u16 *data)
175{
176 u16 command;
177
178 /*
179 * Initialize the eeprom register
180 */
181 eeprom_93cx6_startup(eeprom);
182
183 /*
184 * Select the read opcode and the word to be read.
185 */
186 command = (PCI_EEPROM_READ_OPCODE << eeprom->width) | word;
187 eeprom_93cx6_write_bits(eeprom, data: command,
188 PCI_EEPROM_WIDTH_OPCODE + eeprom->width);
189
190 if (has_quirk_extra_read_cycle(eeprom)) {
191 eeprom_93cx6_pulse_high(eeprom);
192 eeprom_93cx6_pulse_low(eeprom);
193 }
194
195 /*
196 * Read the requested 16 bits.
197 */
198 eeprom_93cx6_read_bits(eeprom, data, count: 16);
199
200 /*
201 * Cleanup eeprom register.
202 */
203 eeprom_93cx6_cleanup(eeprom);
204}
205EXPORT_SYMBOL_GPL(eeprom_93cx6_read);
206
207/**
208 * eeprom_93cx6_multiread - Read multiple words from eeprom
209 * @eeprom: Pointer to eeprom structure
210 * @word: Word index from where we should start reading
211 * @data: target pointer where the information will have to be stored
212 * @words: Number of words that should be read.
213 *
214 * This function will read all requested words from the eeprom,
215 * this is done by calling eeprom_93cx6_read() multiple times.
216 * But with the additional change that while the eeprom_93cx6_read
217 * will return host ordered bytes, this method will return little
218 * endian words.
219 */
220void eeprom_93cx6_multiread(struct eeprom_93cx6 *eeprom, const u8 word,
221 __le16 *data, const u16 words)
222{
223 unsigned int i;
224 u16 tmp;
225
226 for (i = 0; i < words; i++) {
227 tmp = 0;
228 eeprom_93cx6_read(eeprom, word + i, &tmp);
229 data[i] = cpu_to_le16(tmp);
230 }
231}
232EXPORT_SYMBOL_GPL(eeprom_93cx6_multiread);
233
234/**
235 * eeprom_93cx6_readb - Read a byte from eeprom
236 * @eeprom: Pointer to eeprom structure
237 * @byte: Byte index from where we should start reading
238 * @data: target pointer where the information will have to be stored
239 *
240 * This function will read a byte of the eeprom data
241 * into the given data pointer.
242 */
243void eeprom_93cx6_readb(struct eeprom_93cx6 *eeprom, const u8 byte,
244 u8 *data)
245{
246 u16 command;
247 u16 tmp;
248
249 /*
250 * Initialize the eeprom register
251 */
252 eeprom_93cx6_startup(eeprom);
253
254 /*
255 * Select the read opcode and the byte to be read.
256 */
257 command = (PCI_EEPROM_READ_OPCODE << (eeprom->width + 1)) | byte;
258 eeprom_93cx6_write_bits(eeprom, data: command,
259 PCI_EEPROM_WIDTH_OPCODE + eeprom->width + 1);
260
261 if (has_quirk_extra_read_cycle(eeprom)) {
262 eeprom_93cx6_pulse_high(eeprom);
263 eeprom_93cx6_pulse_low(eeprom);
264 }
265
266 /*
267 * Read the requested 8 bits.
268 */
269 eeprom_93cx6_read_bits(eeprom, data: &tmp, count: 8);
270 *data = tmp & 0xff;
271
272 /*
273 * Cleanup eeprom register.
274 */
275 eeprom_93cx6_cleanup(eeprom);
276}
277EXPORT_SYMBOL_GPL(eeprom_93cx6_readb);
278
279/**
280 * eeprom_93cx6_multireadb - Read multiple bytes from eeprom
281 * @eeprom: Pointer to eeprom structure
282 * @byte: Index from where we should start reading
283 * @data: target pointer where the information will have to be stored
284 * @bytes: Number of bytes that should be read.
285 *
286 * This function will read all requested bytes from the eeprom,
287 * this is done by calling eeprom_93cx6_readb() multiple times.
288 */
289void eeprom_93cx6_multireadb(struct eeprom_93cx6 *eeprom, const u8 byte,
290 u8 *data, const u16 bytes)
291{
292 unsigned int i;
293
294 for (i = 0; i < bytes; i++)
295 eeprom_93cx6_readb(eeprom, byte + i, &data[i]);
296}
297EXPORT_SYMBOL_GPL(eeprom_93cx6_multireadb);
298
299/**
300 * eeprom_93cx6_wren - set the write enable state
301 * @eeprom: Pointer to eeprom structure
302 * @enable: true to enable writes, otherwise disable writes
303 *
304 * Set the EEPROM write enable state to either allow or deny
305 * writes depending on the @enable value.
306 */
307void eeprom_93cx6_wren(struct eeprom_93cx6 *eeprom, bool enable)
308{
309 u16 command;
310
311 /* start the command */
312 eeprom_93cx6_startup(eeprom);
313
314 /* create command to enable/disable */
315
316 command = enable ? PCI_EEPROM_EWEN_OPCODE : PCI_EEPROM_EWDS_OPCODE;
317 command <<= (eeprom->width - 2);
318
319 eeprom_93cx6_write_bits(eeprom, data: command,
320 PCI_EEPROM_WIDTH_OPCODE + eeprom->width);
321
322 eeprom_93cx6_cleanup(eeprom);
323}
324EXPORT_SYMBOL_GPL(eeprom_93cx6_wren);
325
326/**
327 * eeprom_93cx6_write - write data to the EEPROM
328 * @eeprom: Pointer to eeprom structure
329 * @addr: Address to write data to.
330 * @data: The data to write to address @addr.
331 *
332 * Write the @data to the specified @addr in the EEPROM and
333 * waiting for the device to finish writing.
334 *
335 * Note, since we do not expect large number of write operations
336 * we delay in between parts of the operation to avoid using excessive
337 * amounts of CPU time busy waiting.
338 */
339void eeprom_93cx6_write(struct eeprom_93cx6 *eeprom, u8 addr, u16 data)
340{
341 int timeout = 100;
342 u16 command;
343
344 /* start the command */
345 eeprom_93cx6_startup(eeprom);
346
347 command = PCI_EEPROM_WRITE_OPCODE << eeprom->width;
348 command |= addr;
349
350 /* send write command */
351 eeprom_93cx6_write_bits(eeprom, data: command,
352 PCI_EEPROM_WIDTH_OPCODE + eeprom->width);
353
354 /* send data */
355 eeprom_93cx6_write_bits(eeprom, data, count: 16);
356
357 /* get ready to check for busy */
358 eeprom->drive_data = 0;
359 eeprom->reg_chip_select = 1;
360 eeprom->register_write(eeprom);
361
362 /* wait at-least 250ns to get DO to be the busy signal */
363 usleep_range(min: 1000, max: 2000);
364
365 /* wait for DO to go high to signify finish */
366
367 while (true) {
368 eeprom->register_read(eeprom);
369
370 if (eeprom->reg_data_out)
371 break;
372
373 usleep_range(min: 1000, max: 2000);
374
375 if (--timeout <= 0) {
376 printk(KERN_ERR "%s: timeout\n", __func__);
377 break;
378 }
379 }
380
381 eeprom_93cx6_cleanup(eeprom);
382}
383EXPORT_SYMBOL_GPL(eeprom_93cx6_write);
384