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 
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 
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 
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 
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 
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 
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  */
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  */
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  */
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  */
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  */
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  */
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