1/*
2 * Copyright (C) 2004 - 2006 rt2x00 SourceForge Project
3 * <http://rt2x00.serialmonkey.com>
4 *
5 * This program is free software; you can redistribute it and/or modify
6 * it under the terms of the GNU General Public License as published by
7 * the Free Software Foundation; either version 2 of the License, or
8 * (at your option) any later version.
9 *
10 * This program is distributed in the hope that it will be useful,
11 * but WITHOUT ANY WARRANTY; without even the implied warranty of
12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
13 * GNU General Public License for more details.
14 *
15 * Module: eeprom_93cx6
16 * Abstract: EEPROM reader routines for 93cx6 chipsets.
17 * Supported chipsets: 93c46 & 93c66.
18 */
19
20#include <linux/kernel.h>
21#include <linux/module.h>
22#include <linux/delay.h>
23#include <linux/eeprom_93cx6.h>
24
25MODULE_AUTHOR("http://rt2x00.serialmonkey.com");
26MODULE_VERSION("1.0");
27MODULE_DESCRIPTION("EEPROM 93cx6 chip driver");
28MODULE_LICENSE("GPL");
29
30static inline void eeprom_93cx6_pulse_high(struct eeprom_93cx6 *eeprom)
31{
32	eeprom->reg_data_clock = 1;
33	eeprom->register_write(eeprom);
34
35	/*
36	 * Add a short delay for the pulse to work.
37	 * According to the specifications the "maximum minimum"
38	 * time should be 450ns.
39	 */
40	ndelay(450);
41}
42
43static inline void eeprom_93cx6_pulse_low(struct eeprom_93cx6 *eeprom)
44{
45	eeprom->reg_data_clock = 0;
46	eeprom->register_write(eeprom);
47
48	/*
49	 * Add a short delay for the pulse to work.
50	 * According to the specifications the "maximum minimum"
51	 * time should be 450ns.
52	 */
53	ndelay(450);
54}
55
56static void eeprom_93cx6_startup(struct eeprom_93cx6 *eeprom)
57{
58	/*
59	 * Clear all flags, and enable chip select.
60	 */
61	eeprom->register_read(eeprom);
62	eeprom->reg_data_in = 0;
63	eeprom->reg_data_out = 0;
64	eeprom->reg_data_clock = 0;
65	eeprom->reg_chip_select = 1;
66	eeprom->drive_data = 1;
67	eeprom->register_write(eeprom);
68
69	/*
70	 * kick a pulse.
71	 */
72	eeprom_93cx6_pulse_high(eeprom);
73	eeprom_93cx6_pulse_low(eeprom);
74}
75
76static void eeprom_93cx6_cleanup(struct eeprom_93cx6 *eeprom)
77{
78	/*
79	 * Clear chip_select and data_in flags.
80	 */
81	eeprom->register_read(eeprom);
82	eeprom->reg_data_in = 0;
83	eeprom->reg_chip_select = 0;
84	eeprom->register_write(eeprom);
85
86	/*
87	 * kick a pulse.
88	 */
89	eeprom_93cx6_pulse_high(eeprom);
90	eeprom_93cx6_pulse_low(eeprom);
91}
92
93static void eeprom_93cx6_write_bits(struct eeprom_93cx6 *eeprom,
94	const u16 data, const u16 count)
95{
96	unsigned int i;
97
98	eeprom->register_read(eeprom);
99
100	/*
101	 * Clear data flags.
102	 */
103	eeprom->reg_data_in = 0;
104	eeprom->reg_data_out = 0;
105	eeprom->drive_data = 1;
106
107	/*
108	 * Start writing all bits.
109	 */
110	for (i = count; i > 0; i--) {
111		/*
112		 * Check if this bit needs to be set.
113		 */
114		eeprom->reg_data_in = !!(data & (1 << (i - 1)));
115
116		/*
117		 * Write the bit to the eeprom register.
118		 */
119		eeprom->register_write(eeprom);
120
121		/*
122		 * Kick a pulse.
123		 */
124		eeprom_93cx6_pulse_high(eeprom);
125		eeprom_93cx6_pulse_low(eeprom);
126	}
127
128	eeprom->reg_data_in = 0;
129	eeprom->register_write(eeprom);
130}
131
132static void eeprom_93cx6_read_bits(struct eeprom_93cx6 *eeprom,
133	u16 *data, const u16 count)
134{
135	unsigned int i;
136	u16 buf = 0;
137
138	eeprom->register_read(eeprom);
139
140	/*
141	 * Clear data flags.
142	 */
143	eeprom->reg_data_in = 0;
144	eeprom->reg_data_out = 0;
145	eeprom->drive_data = 0;
146
147	/*
148	 * Start reading all bits.
149	 */
150	for (i = count; i > 0; i--) {
151		eeprom_93cx6_pulse_high(eeprom);
152
153		eeprom->register_read(eeprom);
154
155		/*
156		 * Clear data_in flag.
157		 */
158		eeprom->reg_data_in = 0;
159
160		/*
161		 * Read if the bit has been set.
162		 */
163		if (eeprom->reg_data_out)
164			buf |= (1 << (i - 1));
165
166		eeprom_93cx6_pulse_low(eeprom);
167	}
168
169	*data = buf;
170}
171
172/**
173 * eeprom_93cx6_read - Read a word from eeprom
174 * @eeprom: Pointer to eeprom structure
175 * @word: Word index from where we should start reading
176 * @data: target pointer where the information will have to be stored
177 *
178 * This function will read the eeprom data as host-endian word
179 * into the given data pointer.
180 */
181void eeprom_93cx6_read(struct eeprom_93cx6 *eeprom, const u8 word,
182	u16 *data)
183{
184	u16 command;
185
186	/*
187	 * Initialize the eeprom register
188	 */
189	eeprom_93cx6_startup(eeprom);
190
191	/*
192	 * Select the read opcode and the word to be read.
193	 */
194	command = (PCI_EEPROM_READ_OPCODE << eeprom->width) | word;
195	eeprom_93cx6_write_bits(eeprom, command,
196		PCI_EEPROM_WIDTH_OPCODE + eeprom->width);
197
198	/*
199	 * Read the requested 16 bits.
200	 */
201	eeprom_93cx6_read_bits(eeprom, data, 16);
202
203	/*
204	 * Cleanup eeprom register.
205	 */
206	eeprom_93cx6_cleanup(eeprom);
207}
208EXPORT_SYMBOL_GPL(eeprom_93cx6_read);
209
210/**
211 * eeprom_93cx6_multiread - Read multiple words from eeprom
212 * @eeprom: Pointer to eeprom structure
213 * @word: Word index from where we should start reading
214 * @data: target pointer where the information will have to be stored
215 * @words: Number of words that should be read.
216 *
217 * This function will read all requested words from the eeprom,
218 * this is done by calling eeprom_93cx6_read() multiple times.
219 * But with the additional change that while the eeprom_93cx6_read
220 * will return host ordered bytes, this method will return little
221 * endian words.
222 */
223void eeprom_93cx6_multiread(struct eeprom_93cx6 *eeprom, const u8 word,
224	__le16 *data, const u16 words)
225{
226	unsigned int i;
227	u16 tmp;
228
229	for (i = 0; i < words; i++) {
230		tmp = 0;
231		eeprom_93cx6_read(eeprom, word + i, &tmp);
232		data[i] = cpu_to_le16(tmp);
233	}
234}
235EXPORT_SYMBOL_GPL(eeprom_93cx6_multiread);
236
237/**
238 * eeprom_93cx6_readb - Read a byte from eeprom
239 * @eeprom: Pointer to eeprom structure
240 * @word: Byte index from where we should start reading
241 * @data: target pointer where the information will have to be stored
242 *
243 * This function will read a byte of the eeprom data
244 * into the given data pointer.
245 */
246void eeprom_93cx6_readb(struct eeprom_93cx6 *eeprom, const u8 byte,
247	u8 *data)
248{
249	u16 command;
250	u16 tmp;
251
252	/*
253	 * Initialize the eeprom register
254	 */
255	eeprom_93cx6_startup(eeprom);
256
257	/*
258	 * Select the read opcode and the byte to be read.
259	 */
260	command = (PCI_EEPROM_READ_OPCODE << (eeprom->width + 1)) | byte;
261	eeprom_93cx6_write_bits(eeprom, command,
262		PCI_EEPROM_WIDTH_OPCODE + eeprom->width + 1);
263
264	/*
265	 * Read the requested 8 bits.
266	 */
267	eeprom_93cx6_read_bits(eeprom, &tmp, 8);
268	*data = tmp & 0xff;
269
270	/*
271	 * Cleanup eeprom register.
272	 */
273	eeprom_93cx6_cleanup(eeprom);
274}
275EXPORT_SYMBOL_GPL(eeprom_93cx6_readb);
276
277/**
278 * eeprom_93cx6_multireadb - Read multiple bytes from eeprom
279 * @eeprom: Pointer to eeprom structure
280 * @byte: Index from where we should start reading
281 * @data: target pointer where the information will have to be stored
282 * @words: Number of bytes that should be read.
283 *
284 * This function will read all requested bytes from the eeprom,
285 * this is done by calling eeprom_93cx6_readb() multiple times.
286 */
287void eeprom_93cx6_multireadb(struct eeprom_93cx6 *eeprom, const u8 byte,
288	u8 *data, const u16 bytes)
289{
290	unsigned int i;
291
292	for (i = 0; i < bytes; i++)
293		eeprom_93cx6_readb(eeprom, byte + i, &data[i]);
294}
295EXPORT_SYMBOL_GPL(eeprom_93cx6_multireadb);
296
297/**
298 * eeprom_93cx6_wren - set the write enable state
299 * @eeprom: Pointer to eeprom structure
300 * @enable: true to enable writes, otherwise disable writes
301 *
302 * Set the EEPROM write enable state to either allow or deny
303 * writes depending on the @enable value.
304 */
305void eeprom_93cx6_wren(struct eeprom_93cx6 *eeprom, bool enable)
306{
307	u16 command;
308
309	/* start the command */
310	eeprom_93cx6_startup(eeprom);
311
312	/* create command to enable/disable */
313
314	command = enable ? PCI_EEPROM_EWEN_OPCODE : PCI_EEPROM_EWDS_OPCODE;
315	command <<= (eeprom->width - 2);
316
317	eeprom_93cx6_write_bits(eeprom, command,
318				PCI_EEPROM_WIDTH_OPCODE + eeprom->width);
319
320	eeprom_93cx6_cleanup(eeprom);
321}
322EXPORT_SYMBOL_GPL(eeprom_93cx6_wren);
323
324/**
325 * eeprom_93cx6_write - write data to the EEPROM
326 * @eeprom: Pointer to eeprom structure
327 * @addr: Address to write data to.
328 * @data: The data to write to address @addr.
329 *
330 * Write the @data to the specified @addr in the EEPROM and
331 * waiting for the device to finish writing.
332 *
333 * Note, since we do not expect large number of write operations
334 * we delay in between parts of the operation to avoid using excessive
335 * amounts of CPU time busy waiting.
336 */
337void eeprom_93cx6_write(struct eeprom_93cx6 *eeprom, u8 addr, u16 data)
338{
339	int timeout = 100;
340	u16 command;
341
342	/* start the command */
343	eeprom_93cx6_startup(eeprom);
344
345	command = PCI_EEPROM_WRITE_OPCODE << eeprom->width;
346	command |= addr;
347
348	/* send write command */
349	eeprom_93cx6_write_bits(eeprom, command,
350				PCI_EEPROM_WIDTH_OPCODE + eeprom->width);
351
352	/* send data */
353	eeprom_93cx6_write_bits(eeprom, data, 16);
354
355	/* get ready to check for busy */
356	eeprom->drive_data = 0;
357	eeprom->reg_chip_select = 1;
358	eeprom->register_write(eeprom);
359
360	/* wait at-least 250ns to get DO to be the busy signal */
361	usleep_range(1000, 2000);
362
363	/* wait for DO to go high to signify finish */
364
365	while (true) {
366		eeprom->register_read(eeprom);
367
368		if (eeprom->reg_data_out)
369			break;
370
371		usleep_range(1000, 2000);
372
373		if (--timeout <= 0) {
374			printk(KERN_ERR "%s: timeout\n", __func__);
375			break;
376		}
377	}
378
379	eeprom_93cx6_cleanup(eeprom);
380}
381EXPORT_SYMBOL_GPL(eeprom_93cx6_write);
382