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
16MODULE_AUTHOR("http://rt2x00.serialmonkey.com");
17MODULE_VERSION("1.0");
18MODULE_DESCRIPTION("EEPROM 93cx6 chip driver");
19MODULE_LICENSE("GPL");
20
21static 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
34static 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
47static 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
67static 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
84static 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
123static 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 */
172void 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}
199EXPORT_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 */
214void 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}
226EXPORT_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 */
237void 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}
266EXPORT_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 */
278void 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}
286EXPORT_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 */
296void 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}
313EXPORT_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 */
328void 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}
372EXPORT_SYMBOL_GPL(eeprom_93cx6_write);
373