blob: eddf25b90ca8d66f01eb21a047e00700d660fa64 [file] [log] [blame]
Wolfram Sang738ac062019-01-19 13:16:54 +01001// SPDX-License-Identifier: GPL-2.0+
2/*
3 * i2c-algo-bit.c: i2c driver algorithms for bit-shift adapters
4 *
David Brownellcf978ab2008-01-27 18:14:46 +01005 * Copyright (C) 1995-2000 Simon G. Vogl
Wolfram Sang738ac062019-01-19 13:16:54 +01006 *
7 * With some changes from Frodo Looijaard <frodol@dds.nl>, Kyösti Mälkki
8 * <kmalkki@cc.hut.fi> and Jean Delvare <jdelvare@suse.de>
9 */
Linus Torvalds1da177e2005-04-16 15:20:36 -070010
11#include <linux/kernel.h>
12#include <linux/module.h>
13#include <linux/delay.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070014#include <linux/errno.h>
15#include <linux/sched.h>
16#include <linux/i2c.h>
17#include <linux/i2c-algo-bit.h>
18
19
20/* ----- global defines ----------------------------------------------- */
Linus Torvalds1da177e2005-04-16 15:20:36 -070021
Jean Delvare494dbb62007-05-01 23:26:33 +020022#ifdef DEBUG
23#define bit_dbg(level, dev, format, args...) \
24 do { \
25 if (i2c_debug >= level) \
26 dev_dbg(dev, format, ##args); \
27 } while (0)
28#else
29#define bit_dbg(level, dev, format, args...) \
30 do {} while (0)
31#endif /* DEBUG */
Linus Torvalds1da177e2005-04-16 15:20:36 -070032
33/* ----- global variables --------------------------------------------- */
34
Linus Torvalds1da177e2005-04-16 15:20:36 -070035static int bit_test; /* see if the line-setting functions work */
Jean Delvare1bddab72011-10-30 13:47:25 +010036module_param(bit_test, int, S_IRUGO);
37MODULE_PARM_DESC(bit_test, "lines testing - 0 off; 1 report; 2 fail if stuck");
Jean Delvare494dbb62007-05-01 23:26:33 +020038
39#ifdef DEBUG
40static int i2c_debug = 1;
41module_param(i2c_debug, int, S_IRUGO | S_IWUSR);
42MODULE_PARM_DESC(i2c_debug,
43 "debug level - 0 off; 1 normal; 2 verbose; 3 very verbose");
44#endif
Linus Torvalds1da177e2005-04-16 15:20:36 -070045
46/* --- setting states on the bus with the right timing: --------------- */
47
David Brownellcf978ab2008-01-27 18:14:46 +010048#define setsda(adap, val) adap->setsda(adap->data, val)
49#define setscl(adap, val) adap->setscl(adap->data, val)
50#define getsda(adap) adap->getsda(adap->data)
51#define getscl(adap) adap->getscl(adap->data)
Linus Torvalds1da177e2005-04-16 15:20:36 -070052
53static inline void sdalo(struct i2c_algo_bit_data *adap)
54{
David Brownellcf978ab2008-01-27 18:14:46 +010055 setsda(adap, 0);
Jean Delvare424ed672007-05-01 23:26:33 +020056 udelay((adap->udelay + 1) / 2);
Linus Torvalds1da177e2005-04-16 15:20:36 -070057}
58
59static inline void sdahi(struct i2c_algo_bit_data *adap)
60{
David Brownellcf978ab2008-01-27 18:14:46 +010061 setsda(adap, 1);
Jean Delvare424ed672007-05-01 23:26:33 +020062 udelay((adap->udelay + 1) / 2);
Linus Torvalds1da177e2005-04-16 15:20:36 -070063}
64
65static inline void scllo(struct i2c_algo_bit_data *adap)
66{
David Brownellcf978ab2008-01-27 18:14:46 +010067 setscl(adap, 0);
Jean Delvare424ed672007-05-01 23:26:33 +020068 udelay(adap->udelay / 2);
Linus Torvalds1da177e2005-04-16 15:20:36 -070069}
70
71/*
72 * Raise scl line, and do checking for delays. This is necessary for slower
73 * devices.
74 */
Jean Delvare7b288a02006-09-03 22:22:12 +020075static int sclhi(struct i2c_algo_bit_data *adap)
Linus Torvalds1da177e2005-04-16 15:20:36 -070076{
77 unsigned long start;
78
David Brownellcf978ab2008-01-27 18:14:46 +010079 setscl(adap, 1);
Linus Torvalds1da177e2005-04-16 15:20:36 -070080
81 /* Not all adapters have scl sense line... */
Jean Delvare7b288a02006-09-03 22:22:12 +020082 if (!adap->getscl)
83 goto done;
Linus Torvalds1da177e2005-04-16 15:20:36 -070084
David Brownellcf978ab2008-01-27 18:14:46 +010085 start = jiffies;
86 while (!getscl(adap)) {
87 /* This hw knows how to read the clock line, so we wait
88 * until it actually gets high. This is safer as some
89 * chips may hold it low ("clock stretching") while they
90 * are processing data internally.
91 */
Ville Syrjala8ee161c2012-03-15 18:11:05 +010092 if (time_after(jiffies, start + adap->timeout)) {
93 /* Test one last time, as we may have been preempted
94 * between last check and timeout test.
95 */
96 if (getscl(adap))
97 break;
Linus Torvalds1da177e2005-04-16 15:20:36 -070098 return -ETIMEDOUT;
Ville Syrjala8ee161c2012-03-15 18:11:05 +010099 }
Jean Delvare41101a32012-03-26 21:47:19 +0200100 cpu_relax();
Linus Torvalds1da177e2005-04-16 15:20:36 -0700101 }
Jean Delvare494dbb62007-05-01 23:26:33 +0200102#ifdef DEBUG
103 if (jiffies != start && i2c_debug >= 3)
Jan Kundrát1204d122018-08-28 10:07:40 +0200104 pr_debug("i2c-algo-bit: needed %ld jiffies for SCL to go high\n",
105 jiffies - start);
Jean Delvare494dbb62007-05-01 23:26:33 +0200106#endif
Jean Delvare7b288a02006-09-03 22:22:12 +0200107
108done:
Linus Torvalds1da177e2005-04-16 15:20:36 -0700109 udelay(adap->udelay);
110 return 0;
David Brownellcf978ab2008-01-27 18:14:46 +0100111}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700112
113
114/* --- other auxiliary functions -------------------------------------- */
David Brownellcf978ab2008-01-27 18:14:46 +0100115static void i2c_start(struct i2c_algo_bit_data *adap)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700116{
117 /* assert: scl, sda are high */
Jean Delvare424ed672007-05-01 23:26:33 +0200118 setsda(adap, 0);
119 udelay(adap->udelay);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700120 scllo(adap);
121}
122
David Brownellcf978ab2008-01-27 18:14:46 +0100123static void i2c_repstart(struct i2c_algo_bit_data *adap)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700124{
Jean Delvare424ed672007-05-01 23:26:33 +0200125 /* assert: scl is low */
Jean Delvare424ed672007-05-01 23:26:33 +0200126 sdahi(adap);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700127 sclhi(adap);
Jean Delvare424ed672007-05-01 23:26:33 +0200128 setsda(adap, 0);
129 udelay(adap->udelay);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700130 scllo(adap);
131}
132
133
David Brownellcf978ab2008-01-27 18:14:46 +0100134static void i2c_stop(struct i2c_algo_bit_data *adap)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700135{
Linus Torvalds1da177e2005-04-16 15:20:36 -0700136 /* assert: scl is low */
137 sdalo(adap);
David Brownellcf978ab2008-01-27 18:14:46 +0100138 sclhi(adap);
Jean Delvare424ed672007-05-01 23:26:33 +0200139 setsda(adap, 1);
140 udelay(adap->udelay);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700141}
142
143
144
David Brownellcf978ab2008-01-27 18:14:46 +0100145/* send a byte without start cond., look for arbitration,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700146 check ackn. from slave */
147/* returns:
148 * 1 if the device acknowledged
149 * 0 if the device did not ack
150 * -ETIMEDOUT if an error occurred (while raising the scl line)
151 */
Jean Delvare494dbb62007-05-01 23:26:33 +0200152static int i2c_outb(struct i2c_adapter *i2c_adap, unsigned char c)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700153{
154 int i;
155 int sb;
156 int ack;
157 struct i2c_algo_bit_data *adap = i2c_adap->algo_data;
158
159 /* assert: scl is low */
David Brownellcf978ab2008-01-27 18:14:46 +0100160 for (i = 7; i >= 0; i--) {
Jean Delvare494dbb62007-05-01 23:26:33 +0200161 sb = (c >> i) & 1;
David Brownellcf978ab2008-01-27 18:14:46 +0100162 setsda(adap, sb);
Jean Delvare424ed672007-05-01 23:26:33 +0200163 udelay((adap->udelay + 1) / 2);
David Brownellcf978ab2008-01-27 18:14:46 +0100164 if (sclhi(adap) < 0) { /* timed out */
Jan Kundrát1204d122018-08-28 10:07:40 +0200165 bit_dbg(1, &i2c_adap->dev,
166 "i2c_outb: 0x%02x, timeout at bit #%d\n",
167 (int)c, i);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700168 return -ETIMEDOUT;
David Brownellcf978ab2008-01-27 18:14:46 +0100169 }
170 /* FIXME do arbitration here:
171 * if (sb && !getsda(adap)) -> ouch! Get out of here.
172 *
173 * Report a unique code, so higher level code can retry
174 * the whole (combined) message and *NOT* issue STOP.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700175 */
Jean Delvare424ed672007-05-01 23:26:33 +0200176 scllo(adap);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700177 }
178 sdahi(adap);
David Brownellcf978ab2008-01-27 18:14:46 +0100179 if (sclhi(adap) < 0) { /* timeout */
Jan Kundrát1204d122018-08-28 10:07:40 +0200180 bit_dbg(1, &i2c_adap->dev,
181 "i2c_outb: 0x%02x, timeout at ack\n", (int)c);
Jean Delvare494dbb62007-05-01 23:26:33 +0200182 return -ETIMEDOUT;
David Brownellcf978ab2008-01-27 18:14:46 +0100183 }
184
185 /* read ack: SDA should be pulled down by slave, or it may
186 * NAK (usually to report problems with the data we wrote).
Heiner Kallweit9dfee142023-01-18 22:54:03 +0100187 * Always report ACK if SDA is write-only.
David Brownellcf978ab2008-01-27 18:14:46 +0100188 */
Heiner Kallweit9dfee142023-01-18 22:54:03 +0100189 ack = !adap->getsda || !getsda(adap); /* ack: sda is pulled low -> success */
Jean Delvare494dbb62007-05-01 23:26:33 +0200190 bit_dbg(2, &i2c_adap->dev, "i2c_outb: 0x%02x %s\n", (int)c,
191 ack ? "A" : "NA");
Linus Torvalds1da177e2005-04-16 15:20:36 -0700192
Linus Torvalds1da177e2005-04-16 15:20:36 -0700193 scllo(adap);
Jean Delvare494dbb62007-05-01 23:26:33 +0200194 return ack;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700195 /* assert: scl is low (sda undef) */
196}
197
198
David Brownellcf978ab2008-01-27 18:14:46 +0100199static int i2c_inb(struct i2c_adapter *i2c_adap)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700200{
201 /* read byte via i2c port, without start/stop sequence */
202 /* acknowledge is sent in i2c_read. */
203 int i;
David Brownellcf978ab2008-01-27 18:14:46 +0100204 unsigned char indata = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700205 struct i2c_algo_bit_data *adap = i2c_adap->algo_data;
206
207 /* assert: scl is low */
208 sdahi(adap);
David Brownellcf978ab2008-01-27 18:14:46 +0100209 for (i = 0; i < 8; i++) {
210 if (sclhi(adap) < 0) { /* timeout */
Jan Kundrát1204d122018-08-28 10:07:40 +0200211 bit_dbg(1, &i2c_adap->dev,
212 "i2c_inb: timeout at bit #%d\n",
213 7 - i);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700214 return -ETIMEDOUT;
David Brownellcf978ab2008-01-27 18:14:46 +0100215 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700216 indata *= 2;
David Brownellcf978ab2008-01-27 18:14:46 +0100217 if (getsda(adap))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700218 indata |= 0x01;
Jean Delvare424ed672007-05-01 23:26:33 +0200219 setscl(adap, 0);
220 udelay(i == 7 ? adap->udelay / 2 : adap->udelay);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700221 }
222 /* assert: scl is low */
Jean Delvare494dbb62007-05-01 23:26:33 +0200223 return indata;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700224}
225
226/*
227 * Sanity check for the adapter hardware - check the reaction of
228 * the bus lines only if it seems to be idle.
229 */
Alex Deucherd3b3e152011-04-17 10:20:19 +0200230static int test_bus(struct i2c_adapter *i2c_adap)
David Brownellcf978ab2008-01-27 18:14:46 +0100231{
Alex Deucherd3b3e152011-04-17 10:20:19 +0200232 struct i2c_algo_bit_data *adap = i2c_adap->algo_data;
233 const char *name = i2c_adap->name;
234 int scl, sda, ret;
235
236 if (adap->pre_xfer) {
237 ret = adap->pre_xfer(i2c_adap);
238 if (ret < 0)
239 return -ENODEV;
240 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700241
Heiner Kallweit9dfee142023-01-18 22:54:03 +0100242 if (adap->getsda == NULL)
243 pr_info("%s: SDA is write-only, testing not possible\n", name);
David Brownellcf978ab2008-01-27 18:14:46 +0100244 if (adap->getscl == NULL)
Heiner Kallweit9dfee142023-01-18 22:54:03 +0100245 pr_info("%s: SCL is write-only, testing not possible\n", name);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700246
Heiner Kallweit9dfee142023-01-18 22:54:03 +0100247 sda = adap->getsda ? getsda(adap) : 1;
248 scl = adap->getscl ? getscl(adap) : 1;
David Brownellcf978ab2008-01-27 18:14:46 +0100249 if (!scl || !sda) {
Heiner Kallweit9dfee142023-01-18 22:54:03 +0100250 pr_warn("%s: bus seems to be busy (scl=%d, sda=%d)\n", name, scl, sda);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700251 goto bailout;
252 }
253
254 sdalo(adap);
Heiner Kallweit9dfee142023-01-18 22:54:03 +0100255 if (adap->getsda && getsda(adap)) {
256 pr_warn("%s: SDA stuck high!\n", name);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700257 goto bailout;
258 }
Heiner Kallweit9dfee142023-01-18 22:54:03 +0100259 if (adap->getscl && !getscl(adap)) {
260 pr_warn("%s: SCL unexpected low while pulling SDA low!\n", name);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700261 goto bailout;
David Brownellcf978ab2008-01-27 18:14:46 +0100262 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700263
264 sdahi(adap);
Heiner Kallweit9dfee142023-01-18 22:54:03 +0100265 if (adap->getsda && !getsda(adap)) {
266 pr_warn("%s: SDA stuck low!\n", name);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700267 goto bailout;
268 }
Heiner Kallweit9dfee142023-01-18 22:54:03 +0100269 if (adap->getscl && !getscl(adap)) {
270 pr_warn("%s: SCL unexpected low while pulling SDA high!\n", name);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700271 goto bailout;
272 }
273
274 scllo(adap);
Heiner Kallweit9dfee142023-01-18 22:54:03 +0100275 if (adap->getscl && getscl(adap)) {
276 pr_warn("%s: SCL stuck high!\n", name);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700277 goto bailout;
278 }
Heiner Kallweit9dfee142023-01-18 22:54:03 +0100279 if (adap->getsda && !getsda(adap)) {
280 pr_warn("%s: SDA unexpected low while pulling SCL low!\n", name);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700281 goto bailout;
282 }
David Brownellcf978ab2008-01-27 18:14:46 +0100283
Linus Torvalds1da177e2005-04-16 15:20:36 -0700284 sclhi(adap);
Heiner Kallweit9dfee142023-01-18 22:54:03 +0100285 if (adap->getscl && !getscl(adap)) {
286 pr_warn("%s: SCL stuck low!\n", name);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700287 goto bailout;
288 }
Heiner Kallweit9dfee142023-01-18 22:54:03 +0100289 if (adap->getsda && !getsda(adap)) {
290 pr_warn("%s: SDA unexpected low while pulling SCL high!\n", name);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700291 goto bailout;
292 }
Alex Deucherd3b3e152011-04-17 10:20:19 +0200293
294 if (adap->post_xfer)
295 adap->post_xfer(i2c_adap);
296
Jean Delvare494dbb62007-05-01 23:26:33 +0200297 pr_info("%s: Test OK\n", name);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700298 return 0;
299bailout:
300 sdahi(adap);
301 sclhi(adap);
Alex Deucherd3b3e152011-04-17 10:20:19 +0200302
303 if (adap->post_xfer)
304 adap->post_xfer(i2c_adap);
305
Linus Torvalds1da177e2005-04-16 15:20:36 -0700306 return -ENODEV;
307}
308
309/* ----- Utility functions
310 */
311
312/* try_address tries to contact a chip for a number of
313 * times before it gives up.
314 * return values:
315 * 1 chip answered
316 * 0 chip did not answer
317 * -x transmission error
318 */
Jean Delvare7b288a02006-09-03 22:22:12 +0200319static int try_address(struct i2c_adapter *i2c_adap,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700320 unsigned char addr, int retries)
321{
322 struct i2c_algo_bit_data *adap = i2c_adap->algo_data;
David Brownell97140342008-07-14 22:38:25 +0200323 int i, ret = 0;
David Brownellcf978ab2008-01-27 18:14:46 +0100324
325 for (i = 0; i <= retries; i++) {
326 ret = i2c_outb(i2c_adap, addr);
Jean Delvare1ecac072007-05-01 23:26:28 +0200327 if (ret == 1 || i == retries)
328 break;
Jean Delvare494dbb62007-05-01 23:26:33 +0200329 bit_dbg(3, &i2c_adap->dev, "emitting stop condition\n");
Linus Torvalds1da177e2005-04-16 15:20:36 -0700330 i2c_stop(adap);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700331 udelay(adap->udelay);
Jean Delvare424ed672007-05-01 23:26:33 +0200332 yield();
Jean Delvare494dbb62007-05-01 23:26:33 +0200333 bit_dbg(3, &i2c_adap->dev, "emitting start condition\n");
Jean Delvare424ed672007-05-01 23:26:33 +0200334 i2c_start(adap);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700335 }
Jean Delvare494dbb62007-05-01 23:26:33 +0200336 if (i && ret)
Jan Kundrát1204d122018-08-28 10:07:40 +0200337 bit_dbg(1, &i2c_adap->dev,
338 "Used %d tries to %s client at 0x%02x: %s\n", i + 1,
Jean Delvare494dbb62007-05-01 23:26:33 +0200339 addr & 1 ? "read from" : "write to", addr >> 1,
340 ret == 1 ? "success" : "failed, timeout?");
Linus Torvalds1da177e2005-04-16 15:20:36 -0700341 return ret;
342}
343
344static int sendbytes(struct i2c_adapter *i2c_adap, struct i2c_msg *msg)
345{
Jean Delvare494dbb62007-05-01 23:26:33 +0200346 const unsigned char *temp = msg->buf;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700347 int count = msg->len;
David Brownellcf978ab2008-01-27 18:14:46 +0100348 unsigned short nak_ok = msg->flags & I2C_M_IGNORE_NAK;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700349 int retval;
David Brownellcf978ab2008-01-27 18:14:46 +0100350 int wrcount = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700351
352 while (count > 0) {
Jean Delvare494dbb62007-05-01 23:26:33 +0200353 retval = i2c_outb(i2c_adap, *temp);
David Brownellcf978ab2008-01-27 18:14:46 +0100354
355 /* OK/ACK; or ignored NAK */
356 if ((retval > 0) || (nak_ok && (retval == 0))) {
357 count--;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700358 temp++;
359 wrcount++;
David Brownellbf3e2d12008-01-27 18:14:46 +0100360
361 /* A slave NAKing the master means the slave didn't like
362 * something about the data it saw. For example, maybe
363 * the SMBus PEC was wrong.
364 */
365 } else if (retval == 0) {
366 dev_err(&i2c_adap->dev, "sendbytes: NAK bailout.\n");
367 return -EIO;
368
369 /* Timeout; or (someday) lost arbitration
370 *
371 * FIXME Lost ARB implies retrying the transaction from
372 * the first message, after the "winning" master issues
373 * its STOP. As a rule, upper layer code has no reason
374 * to know or care about this ... it is *NOT* an error.
375 */
376 } else {
377 dev_err(&i2c_adap->dev, "sendbytes: error %d\n",
378 retval);
379 return retval;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700380 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700381 }
382 return wrcount;
383}
384
David Brownell939bc492007-09-09 22:29:14 +0200385static int acknak(struct i2c_adapter *i2c_adap, int is_ack)
386{
387 struct i2c_algo_bit_data *adap = i2c_adap->algo_data;
388
389 /* assert: sda is high */
390 if (is_ack) /* send ack */
391 setsda(adap, 0);
392 udelay((adap->udelay + 1) / 2);
393 if (sclhi(adap) < 0) { /* timeout */
394 dev_err(&i2c_adap->dev, "readbytes: ack/nak timeout\n");
395 return -ETIMEDOUT;
396 }
397 scllo(adap);
398 return 0;
399}
400
Jean Delvare7b288a02006-09-03 22:22:12 +0200401static int readbytes(struct i2c_adapter *i2c_adap, struct i2c_msg *msg)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700402{
403 int inval;
David Brownellcf978ab2008-01-27 18:14:46 +0100404 int rdcount = 0; /* counts bytes read */
Jean Delvare494dbb62007-05-01 23:26:33 +0200405 unsigned char *temp = msg->buf;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700406 int count = msg->len;
David Brownell939bc492007-09-09 22:29:14 +0200407 const unsigned flags = msg->flags;
Heiner Kallweit9dfee142023-01-18 22:54:03 +0100408 struct i2c_algo_bit_data *adap = i2c_adap->algo_data;
409
410 if (!adap->getsda)
411 return -EOPNOTSUPP;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700412
413 while (count > 0) {
414 inval = i2c_inb(i2c_adap);
David Brownellcf978ab2008-01-27 18:14:46 +0100415 if (inval >= 0) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700416 *temp = inval;
417 rdcount++;
418 } else { /* read timed out */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700419 break;
420 }
421
422 temp++;
423 count--;
424
Jean Delvare3c4bb242007-05-01 23:26:29 +0200425 /* Some SMBus transactions require that we receive the
426 transaction length as the first read byte. */
David Brownell939bc492007-09-09 22:29:14 +0200427 if (rdcount == 1 && (flags & I2C_M_RECV_LEN)) {
Jean Delvare3c4bb242007-05-01 23:26:29 +0200428 if (inval <= 0 || inval > I2C_SMBUS_BLOCK_MAX) {
David Brownell939bc492007-09-09 22:29:14 +0200429 if (!(flags & I2C_M_NO_RD_ACK))
430 acknak(i2c_adap, 0);
Jan Kundrát1204d122018-08-28 10:07:40 +0200431 dev_err(&i2c_adap->dev,
432 "readbytes: invalid block length (%d)\n",
433 inval);
Jean Delvareabc01b22011-10-30 13:47:25 +0100434 return -EPROTO;
Jean Delvare3c4bb242007-05-01 23:26:29 +0200435 }
436 /* The original count value accounts for the extra
437 bytes, that is, either 1 for a regular transaction,
438 or 2 for a PEC transaction. */
439 count += inval;
440 msg->len += inval;
441 }
David Brownell939bc492007-09-09 22:29:14 +0200442
443 bit_dbg(2, &i2c_adap->dev, "readbytes: 0x%02x %s\n",
444 inval,
445 (flags & I2C_M_NO_RD_ACK)
446 ? "(no ack/nak)"
447 : (count ? "A" : "NA"));
448
449 if (!(flags & I2C_M_NO_RD_ACK)) {
450 inval = acknak(i2c_adap, count);
451 if (inval < 0)
452 return inval;
453 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700454 }
455 return rdcount;
456}
457
458/* doAddress initiates the transfer by generating the start condition (in
459 * try_address) and transmits the address in the necessary format to handle
460 * reads, writes as well as 10bit-addresses.
461 * returns:
462 * 0 everything went okay, the chip ack'ed, or IGNORE_NAK flag was set
Jean Delvareabc01b22011-10-30 13:47:25 +0100463 * -x an error occurred (like: -ENXIO if the device did not answer, or
David Brownellcf978ab2008-01-27 18:14:46 +0100464 * -ETIMEDOUT, for example if the lines are stuck...)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700465 */
Jean Delvare7b288a02006-09-03 22:22:12 +0200466static int bit_doAddress(struct i2c_adapter *i2c_adap, struct i2c_msg *msg)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700467{
468 unsigned short flags = msg->flags;
469 unsigned short nak_ok = msg->flags & I2C_M_IGNORE_NAK;
470 struct i2c_algo_bit_data *adap = i2c_adap->algo_data;
471
472 unsigned char addr;
473 int ret, retries;
474
475 retries = nak_ok ? 0 : i2c_adap->retries;
David Brownellcf978ab2008-01-27 18:14:46 +0100476
477 if (flags & I2C_M_TEN) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700478 /* a ten bit address */
Jeffrey (Sheng-Hui) Chucc6bcf72011-11-23 11:33:07 +0100479 addr = 0xf0 | ((msg->addr >> 7) & 0x06);
Jean Delvare494dbb62007-05-01 23:26:33 +0200480 bit_dbg(2, &i2c_adap->dev, "addr0: %d\n", addr);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700481 /* try extended address code...*/
482 ret = try_address(i2c_adap, addr, retries);
483 if ((ret != 1) && !nak_ok) {
Jean Delvare494dbb62007-05-01 23:26:33 +0200484 dev_err(&i2c_adap->dev,
485 "died at extended address code\n");
Jean Delvareabc01b22011-10-30 13:47:25 +0100486 return -ENXIO;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700487 }
488 /* the remaining 8 bit address */
Jeffrey (Sheng-Hui) Chucc6bcf72011-11-23 11:33:07 +0100489 ret = i2c_outb(i2c_adap, msg->addr & 0xff);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700490 if ((ret != 1) && !nak_ok) {
491 /* the chip did not ack / xmission error occurred */
Jean Delvare494dbb62007-05-01 23:26:33 +0200492 dev_err(&i2c_adap->dev, "died at 2nd address code\n");
Jean Delvareabc01b22011-10-30 13:47:25 +0100493 return -ENXIO;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700494 }
David Brownellcf978ab2008-01-27 18:14:46 +0100495 if (flags & I2C_M_RD) {
Jan Kundrát1204d122018-08-28 10:07:40 +0200496 bit_dbg(3, &i2c_adap->dev,
497 "emitting repeated start condition\n");
Linus Torvalds1da177e2005-04-16 15:20:36 -0700498 i2c_repstart(adap);
499 /* okay, now switch into reading mode */
500 addr |= 0x01;
501 ret = try_address(i2c_adap, addr, retries);
David Brownellcf978ab2008-01-27 18:14:46 +0100502 if ((ret != 1) && !nak_ok) {
Jean Delvare494dbb62007-05-01 23:26:33 +0200503 dev_err(&i2c_adap->dev,
504 "died at repeated address code\n");
Jean Delvareabc01b22011-10-30 13:47:25 +0100505 return -EIO;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700506 }
507 }
508 } else { /* normal 7bit address */
Peter Rosinac6d5292018-05-16 09:16:46 +0200509 addr = i2c_8bit_addr_from_msg(msg);
David Brownellcf978ab2008-01-27 18:14:46 +0100510 if (flags & I2C_M_REV_DIR_ADDR)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700511 addr ^= 1;
512 ret = try_address(i2c_adap, addr, retries);
David Brownellcf978ab2008-01-27 18:14:46 +0100513 if ((ret != 1) && !nak_ok)
David Brownell97140342008-07-14 22:38:25 +0200514 return -ENXIO;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700515 }
516
517 return 0;
518}
519
520static int bit_xfer(struct i2c_adapter *i2c_adap,
521 struct i2c_msg msgs[], int num)
522{
523 struct i2c_msg *pmsg;
524 struct i2c_algo_bit_data *adap = i2c_adap->algo_data;
David Brownellcf978ab2008-01-27 18:14:46 +0100525 int i, ret;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700526 unsigned short nak_ok;
527
Jean Delvare0a9c1472010-03-13 20:56:56 +0100528 if (adap->pre_xfer) {
529 ret = adap->pre_xfer(i2c_adap);
530 if (ret < 0)
531 return ret;
532 }
533
Jean Delvare494dbb62007-05-01 23:26:33 +0200534 bit_dbg(3, &i2c_adap->dev, "emitting start condition\n");
Linus Torvalds1da177e2005-04-16 15:20:36 -0700535 i2c_start(adap);
David Brownellcf978ab2008-01-27 18:14:46 +0100536 for (i = 0; i < num; i++) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700537 pmsg = &msgs[i];
David Brownellcf978ab2008-01-27 18:14:46 +0100538 nak_ok = pmsg->flags & I2C_M_IGNORE_NAK;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700539 if (!(pmsg->flags & I2C_M_NOSTART)) {
540 if (i) {
Jean Delvare606fd272017-06-21 09:24:02 +0200541 if (msgs[i - 1].flags & I2C_M_STOP) {
542 bit_dbg(3, &i2c_adap->dev,
543 "emitting enforced stop/start condition\n");
544 i2c_stop(adap);
545 i2c_start(adap);
546 } else {
547 bit_dbg(3, &i2c_adap->dev,
548 "emitting repeated start condition\n");
549 i2c_repstart(adap);
550 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700551 }
552 ret = bit_doAddress(i2c_adap, pmsg);
553 if ((ret != 0) && !nak_ok) {
Jan Kundrát1204d122018-08-28 10:07:40 +0200554 bit_dbg(1, &i2c_adap->dev,
555 "NAK from device addr 0x%02x msg #%d\n",
Jean Delvare494dbb62007-05-01 23:26:33 +0200556 msgs[i].addr, i);
Jean Delvare1ecac072007-05-01 23:26:28 +0200557 goto bailout;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700558 }
559 }
David Brownellcf978ab2008-01-27 18:14:46 +0100560 if (pmsg->flags & I2C_M_RD) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700561 /* read bytes into buffer*/
562 ret = readbytes(i2c_adap, pmsg);
Jean Delvare494dbb62007-05-01 23:26:33 +0200563 if (ret >= 1)
564 bit_dbg(2, &i2c_adap->dev, "read %d byte%s\n",
565 ret, ret == 1 ? "" : "s");
Jean Delvare1ecac072007-05-01 23:26:28 +0200566 if (ret < pmsg->len) {
567 if (ret >= 0)
Jean Delvareabc01b22011-10-30 13:47:25 +0100568 ret = -EIO;
Jean Delvare1ecac072007-05-01 23:26:28 +0200569 goto bailout;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700570 }
571 } else {
572 /* write bytes from buffer */
573 ret = sendbytes(i2c_adap, pmsg);
Jean Delvare494dbb62007-05-01 23:26:33 +0200574 if (ret >= 1)
575 bit_dbg(2, &i2c_adap->dev, "wrote %d byte%s\n",
576 ret, ret == 1 ? "" : "s");
Jean Delvare1ecac072007-05-01 23:26:28 +0200577 if (ret < pmsg->len) {
578 if (ret >= 0)
Jean Delvareabc01b22011-10-30 13:47:25 +0100579 ret = -EIO;
Jean Delvare1ecac072007-05-01 23:26:28 +0200580 goto bailout;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700581 }
582 }
583 }
Jean Delvare1ecac072007-05-01 23:26:28 +0200584 ret = i;
585
586bailout:
Jean Delvare494dbb62007-05-01 23:26:33 +0200587 bit_dbg(3, &i2c_adap->dev, "emitting stop condition\n");
Linus Torvalds1da177e2005-04-16 15:20:36 -0700588 i2c_stop(adap);
Jean Delvare0a9c1472010-03-13 20:56:56 +0100589
590 if (adap->post_xfer)
591 adap->post_xfer(i2c_adap);
Jean Delvare1ecac072007-05-01 23:26:28 +0200592 return ret;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700593}
594
Wolfram Sang8927fbf2019-04-03 14:40:18 +0200595/*
596 * We print a warning when we are not flagged to support atomic transfers but
597 * will try anyhow. That's what the I2C core would do as well. Sadly, we can't
598 * modify the algorithm struct at probe time because this struct is exported
599 * 'const'.
600 */
601static int bit_xfer_atomic(struct i2c_adapter *i2c_adap, struct i2c_msg msgs[],
602 int num)
603{
604 struct i2c_algo_bit_data *adap = i2c_adap->algo_data;
605
606 if (!adap->can_do_atomic)
607 dev_warn(&i2c_adap->dev, "not flagged for atomic transfers\n");
608
609 return bit_xfer(i2c_adap, msgs, num);
610}
611
Linus Torvalds1da177e2005-04-16 15:20:36 -0700612static u32 bit_func(struct i2c_adapter *adap)
613{
Wolfram Sang58d23302021-01-09 13:43:10 +0100614 return I2C_FUNC_I2C | I2C_FUNC_NOSTART | I2C_FUNC_SMBUS_EMUL_ALL |
Linus Torvalds1da177e2005-04-16 15:20:36 -0700615 I2C_FUNC_10BIT_ADDR | I2C_FUNC_PROTOCOL_MANGLING;
616}
617
618
619/* -----exported algorithm data: ------------------------------------- */
620
Daniel Vetterb0209b32012-02-28 00:39:39 +0100621const struct i2c_algorithm i2c_bit_algo = {
Wolfram Sang8927fbf2019-04-03 14:40:18 +0200622 .master_xfer = bit_xfer,
623 .master_xfer_atomic = bit_xfer_atomic,
624 .functionality = bit_func,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700625};
Daniel Vetterb0209b32012-02-28 00:39:39 +0100626EXPORT_SYMBOL(i2c_bit_algo);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700627
Michele Curtief51d3f2016-04-27 21:37:51 +0200628static const struct i2c_adapter_quirks i2c_bit_quirk_no_clk_stretch = {
Nicola Cornaa94d3062015-10-29 12:34:24 +0100629 .flags = I2C_AQ_NO_CLK_STRETCH,
630};
631
David Brownellcf978ab2008-01-27 18:14:46 +0100632/*
633 * registering functions to load algorithms at runtime
Linus Torvalds1da177e2005-04-16 15:20:36 -0700634 */
Jean Delvaref4511712011-01-10 22:11:23 +0100635static int __i2c_bit_add_bus(struct i2c_adapter *adap,
636 int (*add_adapter)(struct i2c_adapter *))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700637{
638 struct i2c_algo_bit_data *bit_adap = adap->algo_data;
Jean Delvareaf5a60b2011-01-10 22:11:23 +0100639 int ret;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700640
641 if (bit_test) {
Alex Deucherd3b3e152011-04-17 10:20:19 +0200642 ret = test_bus(adap);
Jean Delvare1bddab72011-10-30 13:47:25 +0100643 if (bit_test >= 2 && ret < 0)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700644 return -ENODEV;
645 }
646
Linus Torvalds1da177e2005-04-16 15:20:36 -0700647 /* register new adapter to i2c module... */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700648 adap->algo = &i2c_bit_algo;
Jean Delvare8fcfef62009-03-28 21:34:43 +0100649 adap->retries = 3;
Nicola Cornaa94d3062015-10-29 12:34:24 +0100650 if (bit_adap->getscl == NULL)
651 adap->quirks = &i2c_bit_quirk_no_clk_stretch;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700652
Wolfram Sang2173ed02018-06-16 22:37:57 +0900653 /*
654 * We tried forcing SCL/SDA to an initial state here. But that caused a
655 * regression, sadly. Check Bugzilla #200045 for details.
656 */
657
Jean Delvareaf5a60b2011-01-10 22:11:23 +0100658 ret = add_adapter(adap);
659 if (ret < 0)
660 return ret;
661
Heiner Kallweit9dfee142023-01-18 22:54:03 +0100662 if (bit_adap->getsda == NULL)
663 dev_warn(&adap->dev, "Not I2C compliant: can't read SDA\n");
664
665 if (bit_adap->getscl == NULL)
Jean Delvareaf5a60b2011-01-10 22:11:23 +0100666 dev_warn(&adap->dev, "Not I2C compliant: can't read SCL\n");
Heiner Kallweit9dfee142023-01-18 22:54:03 +0100667
668 if (bit_adap->getsda == NULL || bit_adap->getscl == NULL)
Jean Delvareaf5a60b2011-01-10 22:11:23 +0100669 dev_warn(&adap->dev, "Bus may be unreliable\n");
Heiner Kallweit9dfee142023-01-18 22:54:03 +0100670
Jean Delvareaf5a60b2011-01-10 22:11:23 +0100671 return 0;
Jean Delvare0f3b4832007-05-01 23:26:31 +0200672}
673
674int i2c_bit_add_bus(struct i2c_adapter *adap)
675{
Jean Delvaref4511712011-01-10 22:11:23 +0100676 return __i2c_bit_add_bus(adap, i2c_add_adapter);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700677}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700678EXPORT_SYMBOL(i2c_bit_add_bus);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700679
Jean Delvare0f3b4832007-05-01 23:26:31 +0200680int i2c_bit_add_numbered_bus(struct i2c_adapter *adap)
681{
Jean Delvaref4511712011-01-10 22:11:23 +0100682 return __i2c_bit_add_bus(adap, i2c_add_numbered_adapter);
Jean Delvare0f3b4832007-05-01 23:26:31 +0200683}
684EXPORT_SYMBOL(i2c_bit_add_numbered_bus);
685
Linus Torvalds1da177e2005-04-16 15:20:36 -0700686MODULE_AUTHOR("Simon G. Vogl <simon@tk.uni-linz.ac.at>");
687MODULE_DESCRIPTION("I2C-Bus bit-banging algorithm");
688MODULE_LICENSE("GPL");