aboutsummaryrefslogtreecommitdiff
path: root/drivers/misc/eeprom/eeprom_93cx6.c
blob: 0ff4b02177be7b37c64dfe6b5513212ef7afee19 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
/*
 * Copyright (C) 2004 - 2006 rt2x00 SourceForge Project
 * <http://rt2x00.serialmonkey.com>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
 * GNU General Public License for more details.
 *
 * Module: eeprom_93cx6
 * Abstract: EEPROM reader routines for 93cx6 chipsets.
 * Supported chipsets: 93c46 & 93c66.
 */

#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/delay.h>
#include <linux/eeprom_93cx6.h>

MODULE_AUTHOR("http://rt2x00.serialmonkey.com");
MODULE_VERSION("1.0");
MODULE_DESCRIPTION("EEPROM 93cx6 chip driver");
MODULE_LICENSE("GPL");

static inline void eeprom_93cx6_pulse_high(struct eeprom_93cx6 *eeprom)
{
	eeprom->reg_data_clock = 1;
	eeprom->register_write(eeprom);

	/*
	 * Add a short delay for the pulse to work.
	 * According to the specifications the "maximum minimum"
	 * time should be 450ns.
	 */
	ndelay(450);
}

static inline void eeprom_93cx6_pulse_low(struct eeprom_93cx6 *eeprom)
{
	eeprom->reg_data_clock = 0;
	eeprom->register_write(eeprom);

	/*
	 * Add a short delay for the pulse to work.
	 * According to the specifications the "maximum minimum"
	 * time should be 450ns.
	 */
	ndelay(450);
}

static void eeprom_93cx6_startup(struct eeprom_93cx6 *eeprom)
{
	/*
	 * Clear all flags, and enable chip select.
	 */
	eeprom->register_read(eeprom);
	eeprom->reg_data_in = 0;
	eeprom->reg_data_out = 0;
	eeprom->reg_data_clock = 0;
	eeprom->reg_chip_select = 1;
	eeprom->drive_data = 1;
	eeprom->register_write(eeprom);

	/*
	 * kick a pulse.
	 */
	eeprom_93cx6_pulse_high(eeprom);
	eeprom_93cx6_pulse_low(eeprom);
}

static void eeprom_93cx6_cleanup(struct eeprom_93cx6 *eeprom)
{
	/*
	 * Clear chip_select and data_in flags.
	 */
	eeprom->register_read(eeprom);
	eeprom->reg_data_in = 0;
	eeprom->reg_chip_select = 0;
	eeprom->register_write(eeprom);

	/*
	 * kick a pulse.
	 */
	eeprom_93cx6_pulse_high(eeprom);
	eeprom_93cx6_pulse_low(eeprom);
}

static void eeprom_93cx6_write_bits(struct eeprom_93cx6 *eeprom,
	const u16 data, const u16 count)
{
	unsigned int i;

	eeprom->register_read(eeprom);

	/*
	 * Clear data flags.
	 */
	eeprom->reg_data_in = 0;
	eeprom->reg_data_out = 0;
	eeprom->drive_data = 1;

	/*
	 * Start writing all bits.
	 */
	for (i = count; i > 0; i--) {
		/*
		 * Check if this bit needs to be set.
		 */
		eeprom->reg_data_in = !!(data & (1 << (i - 1)));

		/*
		 * Write the bit to the eeprom register.
		 */
		eeprom->register_write(eeprom);

		/*
		 * Kick a pulse.
		 */
		eeprom_93cx6_pulse_high(eeprom);
		eeprom_93cx6_pulse_low(eeprom);
	}

	eeprom->reg_data_in = 0;
	eeprom->register_write(eeprom);
}

static void eeprom_93cx6_read_bits(struct eeprom_93cx6 *eeprom,
	u16 *data, const u16 count)
{
	unsigned int i;
	u16 buf = 0;

	eeprom->register_read(eeprom);

	/*
	 * Clear data flags.
	 */
	eeprom->reg_data_in = 0;
	eeprom->reg_data_out = 0;
	eeprom->drive_data = 0;

	/*
	 * Start reading all bits.
	 */
	for (i = count; i > 0; i--) {
		eeprom_93cx6_pulse_high(eeprom);

		eeprom->register_read(eeprom);

		/*
		 * Clear data_in flag.
		 */
		eeprom->reg_data_in = 0;

		/*
		 * Read if the bit has been set.
		 */
		if (eeprom->reg_data_out)
			buf |= (1 << (i - 1));

		eeprom_93cx6_pulse_low(eeprom);
	}

	*data = buf;
}

/**
 * eeprom_93cx6_read - Read multiple words from eeprom
 * @eeprom: Pointer to eeprom structure
 * @word: Word index from where we should start reading
 * @data: target pointer where the information will have to be stored
 *
 * This function will read the eeprom data as host-endian word
 * into the given data pointer.
 */
void eeprom_93cx6_read(struct eeprom_93cx6 *eeprom, const u8 word,
	u16 *data)
{
	u16 command;

	/*
	 * Initialize the eeprom register
	 */
	eeprom_93cx6_startup(eeprom);

	/*
	 * Select the read opcode and the word to be read.
	 */
	command = (PCI_EEPROM_READ_OPCODE << eeprom->width) | word;
	eeprom_93cx6_write_bits(eeprom, command,
		PCI_EEPROM_WIDTH_OPCODE + eeprom->width);

	/*
	 * Read the requested 16 bits.
	 */
	eeprom_93cx6_read_bits(eeprom, data, 16);

	/*
	 * Cleanup eeprom register.
	 */
	eeprom_93cx6_cleanup(eeprom);
}
EXPORT_SYMBOL_GPL(eeprom_93cx6_read);

/**
 * eeprom_93cx6_multiread - Read multiple words from eeprom
 * @eeprom: Pointer to eeprom structure
 * @word: Word index from where we should start reading
 * @data: target pointer where the information will have to be stored
 * @words: Number of words that should be read.
 *
 * This function will read all requested words from the eeprom,
 * this is done by calling eeprom_93cx6_read() multiple times.
 * But with the additional change that while the eeprom_93cx6_read
 * will return host ordered bytes, this method will return little
 * endian words.
 */
void eeprom_93cx6_multiread(struct eeprom_93cx6 *eeprom, const u8 word,
	__le16 *data, const u16 words)
{
	unsigned int i;
	u16 tmp;

	for (i = 0; i < words; i++) {
		tmp = 0;
		eeprom_93cx6_read(eeprom, word + i, &tmp);
		data[i] = cpu_to_le16(tmp);
	}
}
EXPORT_SYMBOL_GPL(eeprom_93cx6_multiread);

/**
 * eeprom_93cx6_wren - set the write enable state
 * @eeprom: Pointer to eeprom structure
 * @enable: true to enable writes, otherwise disable writes
 *
 * Set the EEPROM write enable state to either allow or deny
 * writes depending on the @enable value.
 */
void eeprom_93cx6_wren(struct eeprom_93cx6 *eeprom, bool enable)
{
	u16 command;

	/* start the command */
	eeprom_93cx6_startup(eeprom);

	/* create command to enable/disable */

	command = enable ? PCI_EEPROM_EWEN_OPCODE : PCI_EEPROM_EWDS_OPCODE;
	command <<= (eeprom->width - 2);

	eeprom_93cx6_write_bits(eeprom, command,
				PCI_EEPROM_WIDTH_OPCODE + eeprom->width);

	eeprom_93cx6_cleanup(eeprom);
}
EXPORT_SYMBOL_GPL(eeprom_93cx6_wren);

/**
 * eeprom_93cx6_write - write data to the EEPROM
 * @eeprom: Pointer to eeprom structure
 * @addr: Address to write data to.
 * @data: The data to write to address @addr.
 *
 * Write the @data to the specified @addr in the EEPROM and
 * waiting for the device to finish writing.
 *
 * Note, since we do not expect large number of write operations
 * we delay in between parts of the operation to avoid using excessive
 * amounts of CPU time busy waiting.
 */
void eeprom_93cx6_write(struct eeprom_93cx6 *eeprom, u8 addr, u16 data)
{
	int timeout = 100;
	u16 command;

	/* start the command */
	eeprom_93cx6_startup(eeprom);

	command = PCI_EEPROM_WRITE_OPCODE << eeprom->width;
	command |= addr;

	/* send write command */
	eeprom_93cx6_write_bits(eeprom, command,
				PCI_EEPROM_WIDTH_OPCODE + eeprom->width);

	/* send data */
	eeprom_93cx6_write_bits(eeprom, data, 16);

	/* get ready to check for busy */
	eeprom->drive_data = 0;
	eeprom->reg_chip_select = 1;
	eeprom->register_write(eeprom);

	/* wait at-least 250ns to get DO to be the busy signal */
	usleep_range(1000, 2000);

	/* wait for DO to go high to signify finish */

	while (true) {
		eeprom->register_read(eeprom);

		if (eeprom->reg_data_out)
			break;

		usleep_range(1000, 2000);

		if (--timeout <= 0) {
			printk(KERN_ERR "%s: timeout\n", __func__);
			break;
		}
	}

	eeprom_93cx6_cleanup(eeprom);
}
EXPORT_SYMBOL_GPL(eeprom_93cx6_write);