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1// SPDX-License-Identifier: GPL-2.0-or-later2/*3 * i2c-algo-pcf.c i2c driver algorithms for PCF8584 adapters4 *5 * Copyright (C) 1995-1997 Simon G. Vogl6 * 1998-2000 Hans Berglund7 *8 * With some changes from Kyösti Mälkki <kmalkki@cc.hut.fi> and9 * Frodo Looijaard <frodol@dds.nl>, and also from Martin Bailey10 * <mbailey@littlefeet-inc.com>11 *12 * Partially rewriten by Oleg I. Vdovikin <vdovikin@jscc.ru> to handle multiple13 * messages, proper stop/repstart signaling during receive, added detect code14 */15 16#include <linux/kernel.h>17#include <linux/module.h>18#include <linux/delay.h>19#include <linux/errno.h>20#include <linux/i2c.h>21#include <linux/i2c-algo-pcf.h>22#include "i2c-algo-pcf.h"23 24 25#define DEB2(x) if (i2c_debug >= 2) x26#define DEB3(x) if (i2c_debug >= 3) x /* print several statistical values */27#define DEBPROTO(x) if (i2c_debug >= 9) x;28 /* debug the protocol by showing transferred bits */29#define DEF_TIMEOUT 1630 31/*32 * module parameters:33 */34static int i2c_debug;35 36/* setting states on the bus with the right timing: */37 38#define set_pcf(adap, ctl, val) adap->setpcf(adap->data, ctl, val)39#define get_pcf(adap, ctl) adap->getpcf(adap->data, ctl)40#define get_own(adap) adap->getown(adap->data)41#define get_clock(adap) adap->getclock(adap->data)42#define i2c_outb(adap, val) adap->setpcf(adap->data, 0, val)43#define i2c_inb(adap) adap->getpcf(adap->data, 0)44 45/* other auxiliary functions */46 47static void i2c_start(struct i2c_algo_pcf_data *adap)48{49 DEBPROTO(printk(KERN_DEBUG "S "));50 set_pcf(adap, 1, I2C_PCF_START);51}52 53static void i2c_repstart(struct i2c_algo_pcf_data *adap)54{55 DEBPROTO(printk(" Sr "));56 set_pcf(adap, 1, I2C_PCF_REPSTART);57}58 59static void i2c_stop(struct i2c_algo_pcf_data *adap)60{61 DEBPROTO(printk("P\n"));62 set_pcf(adap, 1, I2C_PCF_STOP);63}64 65static void handle_lab(struct i2c_algo_pcf_data *adap, const int *status)66{67 DEB2(printk(KERN_INFO68 "i2c-algo-pcf.o: lost arbitration (CSR 0x%02x)\n",69 *status));70 /*71 * Cleanup from LAB -- reset and enable ESO.72 * This resets the PCF8584; since we've lost the bus, no73 * further attempts should be made by callers to clean up74 * (no i2c_stop() etc.)75 */76 set_pcf(adap, 1, I2C_PCF_PIN);77 set_pcf(adap, 1, I2C_PCF_ESO);78 /*79 * We pause for a time period sufficient for any running80 * I2C transaction to complete -- the arbitration logic won't81 * work properly until the next START is seen.82 * It is assumed the bus driver or client has set a proper value.83 *84 * REVISIT: should probably use msleep instead of mdelay if we85 * know we can sleep.86 */87 if (adap->lab_mdelay)88 mdelay(adap->lab_mdelay);89 90 DEB2(printk(KERN_INFO91 "i2c-algo-pcf.o: reset LAB condition (CSR 0x%02x)\n",92 get_pcf(adap, 1)));93}94 95static int wait_for_bb(struct i2c_algo_pcf_data *adap)96{97 98 int timeout = DEF_TIMEOUT;99 int status;100 101 status = get_pcf(adap, 1);102 103 while (!(status & I2C_PCF_BB) && --timeout) {104 udelay(100); /* wait for 100 us */105 status = get_pcf(adap, 1);106 }107 108 if (timeout == 0) {109 printk(KERN_ERR "Timeout waiting for Bus Busy\n");110 return -ETIMEDOUT;111 }112 113 return 0;114}115 116static int wait_for_pin(struct i2c_algo_pcf_data *adap, int *status)117{118 119 int timeout = DEF_TIMEOUT;120 121 *status = get_pcf(adap, 1);122 123 while ((*status & I2C_PCF_PIN) && --timeout) {124 adap->waitforpin(adap->data);125 *status = get_pcf(adap, 1);126 }127 if (*status & I2C_PCF_LAB) {128 handle_lab(adap, status);129 return -EINTR;130 }131 132 if (timeout == 0)133 return -ETIMEDOUT;134 135 return 0;136}137 138/*139 * This should perform the 'PCF8584 initialization sequence' as described140 * in the Philips IC12 data book (1995, Aug 29).141 * There should be a 30 clock cycle wait after reset, I assume this142 * has been fulfilled.143 * There should be a delay at the end equal to the longest I2C message144 * to synchronize the BB-bit (in multimaster systems). How long is145 * this? I assume 1 second is always long enough.146 *147 * vdovikin: added detect code for PCF8584148 */149static int pcf_init_8584 (struct i2c_algo_pcf_data *adap)150{151 unsigned char temp;152 153 DEB3(printk(KERN_DEBUG "i2c-algo-pcf.o: PCF state 0x%02x\n",154 get_pcf(adap, 1)));155 156 /* S1=0x80: S0 selected, serial interface off */157 set_pcf(adap, 1, I2C_PCF_PIN);158 /*159 * check to see S1 now used as R/W ctrl -160 * PCF8584 does that when ESO is zero161 */162 if (((temp = get_pcf(adap, 1)) & 0x7f) != (0)) {163 DEB2(printk(KERN_ERR "i2c-algo-pcf.o: PCF detection failed -- can't select S0 (0x%02x).\n", temp));164 return -ENXIO; /* definitely not PCF8584 */165 }166 167 /* load own address in S0, effective address is (own << 1) */168 i2c_outb(adap, get_own(adap));169 /* check it's really written */170 if ((temp = i2c_inb(adap)) != get_own(adap)) {171 DEB2(printk(KERN_ERR "i2c-algo-pcf.o: PCF detection failed -- can't set S0 (0x%02x).\n", temp));172 return -ENXIO;173 }174 175 /* S1=0xA0, next byte in S2 */176 set_pcf(adap, 1, I2C_PCF_PIN | I2C_PCF_ES1);177 /* check to see S2 now selected */178 if (((temp = get_pcf(adap, 1)) & 0x7f) != I2C_PCF_ES1) {179 DEB2(printk(KERN_ERR "i2c-algo-pcf.o: PCF detection failed -- can't select S2 (0x%02x).\n", temp));180 return -ENXIO;181 }182 183 /* load clock register S2 */184 i2c_outb(adap, get_clock(adap));185 /* check it's really written, the only 5 lowest bits does matter */186 if (((temp = i2c_inb(adap)) & 0x1f) != get_clock(adap)) {187 DEB2(printk(KERN_ERR "i2c-algo-pcf.o: PCF detection failed -- can't set S2 (0x%02x).\n", temp));188 return -ENXIO;189 }190 191 /* Enable serial interface, idle, S0 selected */192 set_pcf(adap, 1, I2C_PCF_IDLE);193 194 /* check to see PCF is really idled and we can access status register */195 if ((temp = get_pcf(adap, 1)) != (I2C_PCF_PIN | I2C_PCF_BB)) {196 DEB2(printk(KERN_ERR "i2c-algo-pcf.o: PCF detection failed -- can't select S1` (0x%02x).\n", temp));197 return -ENXIO;198 }199 200 printk(KERN_DEBUG "i2c-algo-pcf.o: detected and initialized PCF8584.\n");201 202 return 0;203}204 205static int pcf_sendbytes(struct i2c_adapter *i2c_adap, const char *buf,206 int count, int last)207{208 struct i2c_algo_pcf_data *adap = i2c_adap->algo_data;209 int wrcount, status, timeout;210 211 for (wrcount=0; wrcount<count; ++wrcount) {212 DEB2(dev_dbg(&i2c_adap->dev, "i2c_write: writing %2.2X\n",213 buf[wrcount] & 0xff));214 i2c_outb(adap, buf[wrcount]);215 timeout = wait_for_pin(adap, &status);216 if (timeout) {217 if (timeout == -EINTR)218 return -EINTR; /* arbitration lost */219 220 i2c_stop(adap);221 dev_err(&i2c_adap->dev, "i2c_write: error - timeout.\n");222 return -EREMOTEIO; /* got a better one ?? */223 }224 if (status & I2C_PCF_LRB) {225 i2c_stop(adap);226 dev_err(&i2c_adap->dev, "i2c_write: error - no ack.\n");227 return -EREMOTEIO; /* got a better one ?? */228 }229 }230 if (last)231 i2c_stop(adap);232 else233 i2c_repstart(adap);234 235 return wrcount;236}237 238static int pcf_readbytes(struct i2c_adapter *i2c_adap, char *buf,239 int count, int last)240{241 int i, status;242 struct i2c_algo_pcf_data *adap = i2c_adap->algo_data;243 int wfp;244 245 /* increment number of bytes to read by one -- read dummy byte */246 for (i = 0; i <= count; i++) {247 248 if ((wfp = wait_for_pin(adap, &status))) {249 if (wfp == -EINTR)250 return -EINTR; /* arbitration lost */251 252 i2c_stop(adap);253 dev_err(&i2c_adap->dev, "pcf_readbytes timed out.\n");254 return -1;255 }256 257 if ((status & I2C_PCF_LRB) && (i != count)) {258 i2c_stop(adap);259 dev_err(&i2c_adap->dev, "i2c_read: i2c_inb, No ack.\n");260 return -1;261 }262 263 if (i == count - 1) {264 set_pcf(adap, 1, I2C_PCF_ESO);265 } else if (i == count) {266 if (last)267 i2c_stop(adap);268 else269 i2c_repstart(adap);270 }271 272 if (i)273 buf[i - 1] = i2c_inb(adap);274 else275 i2c_inb(adap); /* dummy read */276 }277 278 return i - 1;279}280 281 282static int pcf_doAddress(struct i2c_algo_pcf_data *adap,283 struct i2c_msg *msg)284{285 unsigned char addr = i2c_8bit_addr_from_msg(msg);286 287 if (msg->flags & I2C_M_REV_DIR_ADDR)288 addr ^= 1;289 i2c_outb(adap, addr);290 291 return 0;292}293 294static int pcf_xfer(struct i2c_adapter *i2c_adap,295 struct i2c_msg *msgs,296 int num)297{298 struct i2c_algo_pcf_data *adap = i2c_adap->algo_data;299 struct i2c_msg *pmsg;300 int i;301 int ret=0, timeout, status;302 303 if (adap->xfer_begin)304 adap->xfer_begin(adap->data);305 306 /* Check for bus busy */307 timeout = wait_for_bb(adap);308 if (timeout) {309 DEB2(printk(KERN_ERR "i2c-algo-pcf.o: "310 "Timeout waiting for BB in pcf_xfer\n");)311 i = -EIO;312 goto out;313 }314 315 for (i = 0;ret >= 0 && i < num; i++) {316 pmsg = &msgs[i];317 318 DEB2(printk(KERN_DEBUG "i2c-algo-pcf.o: Doing %s %d bytes to 0x%02x - %d of %d messages\n",319 pmsg->flags & I2C_M_RD ? "read" : "write",320 pmsg->len, pmsg->addr, i + 1, num);)321 322 ret = pcf_doAddress(adap, pmsg);323 324 /* Send START */325 if (i == 0)326 i2c_start(adap);327 328 /* Wait for PIN (pending interrupt NOT) */329 timeout = wait_for_pin(adap, &status);330 if (timeout) {331 if (timeout == -EINTR) {332 /* arbitration lost */333 i = -EINTR;334 goto out;335 }336 i2c_stop(adap);337 DEB2(printk(KERN_ERR "i2c-algo-pcf.o: Timeout waiting "338 "for PIN(1) in pcf_xfer\n");)339 i = -EREMOTEIO;340 goto out;341 }342 343 /* Check LRB (last rcvd bit - slave ack) */344 if (status & I2C_PCF_LRB) {345 i2c_stop(adap);346 DEB2(printk(KERN_ERR "i2c-algo-pcf.o: No LRB(1) in pcf_xfer\n");)347 i = -EREMOTEIO;348 goto out;349 }350 351 DEB3(printk(KERN_DEBUG "i2c-algo-pcf.o: Msg %d, addr=0x%x, flags=0x%x, len=%d\n",352 i, msgs[i].addr, msgs[i].flags, msgs[i].len);)353 354 if (pmsg->flags & I2C_M_RD) {355 ret = pcf_readbytes(i2c_adap, pmsg->buf, pmsg->len,356 (i + 1 == num));357 358 if (ret != pmsg->len) {359 DEB2(printk(KERN_DEBUG "i2c-algo-pcf.o: fail: "360 "only read %d bytes.\n",ret));361 } else {362 DEB2(printk(KERN_DEBUG "i2c-algo-pcf.o: read %d bytes.\n",ret));363 }364 } else {365 ret = pcf_sendbytes(i2c_adap, pmsg->buf, pmsg->len,366 (i + 1 == num));367 368 if (ret != pmsg->len) {369 DEB2(printk(KERN_DEBUG "i2c-algo-pcf.o: fail: "370 "only wrote %d bytes.\n",ret));371 } else {372 DEB2(printk(KERN_DEBUG "i2c-algo-pcf.o: wrote %d bytes.\n",ret));373 }374 }375 }376 377out:378 if (adap->xfer_end)379 adap->xfer_end(adap->data);380 return i;381}382 383static u32 pcf_func(struct i2c_adapter *adap)384{385 return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL |386 I2C_FUNC_PROTOCOL_MANGLING;387}388 389/* exported algorithm data: */390static const struct i2c_algorithm pcf_algo = {391 .master_xfer = pcf_xfer,392 .functionality = pcf_func,393};394 395/*396 * registering functions to load algorithms at runtime397 */398int i2c_pcf_add_bus(struct i2c_adapter *adap)399{400 struct i2c_algo_pcf_data *pcf_adap = adap->algo_data;401 int rval;402 403 DEB2(dev_dbg(&adap->dev, "hw routines registered.\n"));404 405 /* register new adapter to i2c module... */406 adap->algo = &pcf_algo;407 408 if ((rval = pcf_init_8584(pcf_adap)))409 return rval;410 411 rval = i2c_add_adapter(adap);412 413 return rval;414}415EXPORT_SYMBOL(i2c_pcf_add_bus);416 417MODULE_AUTHOR("Hans Berglund <hb@spacetec.no>");418MODULE_DESCRIPTION("I2C-Bus PCF8584 algorithm");419MODULE_LICENSE("GPL");420 421module_param(i2c_debug, int, S_IRUGO | S_IWUSR);422MODULE_PARM_DESC(i2c_debug,423 "debug level - 0 off; 1 normal; 2,3 more verbose; 9 pcf-protocol");424