The Design and Implementation of the FreeBSD Operating System, Second Edition
Now available: The Design and Implementation of the FreeBSD Operating System (Second Edition)


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FreeBSD/Linux Kernel Cross Reference
sys/arm/mv/twsi.c

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    1 /*-
    2  * Copyright (C) 2008 MARVELL INTERNATIONAL LTD.
    3  * All rights reserved.
    4  *
    5  * Developed by Semihalf.
    6  *
    7  * Redistribution and use in source and binary forms, with or without
    8  * modification, are permitted provided that the following conditions
    9  * are met:
   10  * 1. Redistributions of source code must retain the above copyright
   11  *    notice, this list of conditions and the following disclaimer.
   12  * 2. Redistributions in binary form must reproduce the above copyright
   13  *    notice, this list of conditions and the following disclaimer in the
   14  *    documentation and/or other materials provided with the distribution.
   15  * 3. Neither the name of MARVELL nor the names of contributors
   16  *    may be used to endorse or promote products derived from this software
   17  *    without specific prior written permission.
   18  *
   19  * THIS SOFTWARE IS PROVIDED BY AUTHOR AND CONTRIBUTORS ``AS IS'' AND
   20  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   21  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   22  * ARE DISCLAIMED.  IN NO EVENT SHALL AUTHOR OR CONTRIBUTORS BE LIABLE
   23  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   24  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   25  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   26  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   27  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   28  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   29  * SUCH DAMAGE.
   30  */
   31 
   32 /*
   33  * Driver for the TWSI (aka I2C, aka IIC) bus controller found on Marvell
   34  * SoCs. Supports master operation only, and works in polling mode.
   35  *
   36  * Calls to DELAY() are needed per Application Note AN-179 "TWSI Software
   37  * Guidelines for Discovery(TM), Horizon (TM) and Feroceon(TM) Devices".
   38  */
   39 
   40 #include <sys/cdefs.h>
   41 __FBSDID("$FreeBSD: stable/9/sys/arm/mv/twsi.c 209131 2010-06-13 13:28:53Z raj $");
   42 
   43 #include <sys/param.h>
   44 #include <sys/systm.h>
   45 #include <sys/bus.h>
   46 #include <sys/kernel.h>
   47 #include <sys/module.h>
   48 #include <sys/resource.h>
   49 
   50 #include <machine/bus.h>
   51 #include <machine/resource.h>
   52 
   53 #include <sys/rman.h>
   54 
   55 #include <sys/lock.h>
   56 #include <sys/mutex.h>
   57 
   58 #include <dev/iicbus/iiconf.h>
   59 #include <dev/iicbus/iicbus.h>
   60 #include <dev/ofw/ofw_bus.h>
   61 #include <dev/ofw/ofw_bus_subr.h>
   62 
   63 #include "iicbus_if.h"
   64 
   65 #define MV_TWSI_NAME            "twsi"
   66 
   67 #define TWSI_SLAVE_ADDR         0x00
   68 #define TWSI_EXT_SLAVE_ADDR     0x10
   69 #define TWSI_DATA               0x04
   70 
   71 #define TWSI_CONTROL            0x08
   72 #define TWSI_CONTROL_ACK        (1 << 2)
   73 #define TWSI_CONTROL_IFLG       (1 << 3)
   74 #define TWSI_CONTROL_STOP       (1 << 4)
   75 #define TWSI_CONTROL_START      (1 << 5)
   76 #define TWSI_CONTROL_TWSIEN     (1 << 6)
   77 #define TWSI_CONTROL_INTEN      (1 << 7)
   78 
   79 #define TWSI_STATUS                     0x0c
   80 #define TWSI_STATUS_START               0x08
   81 #define TWSI_STATUS_RPTD_START          0x10
   82 #define TWSI_STATUS_ADDR_W_ACK          0x18
   83 #define TWSI_STATUS_DATA_WR_ACK         0x28
   84 #define TWSI_STATUS_ADDR_R_ACK          0x40
   85 #define TWSI_STATUS_DATA_RD_ACK         0x50
   86 #define TWSI_STATUS_DATA_RD_NOACK       0x58
   87 
   88 #define TWSI_BAUD_RATE          0x0c
   89 #define TWSI_BAUD_RATE_94DOT3   0x53 /* N=3, M=10 */
   90 #define TWSI_BAUD_RATE_74DOT1   0x6b /* N=3, M=13 */
   91 #define TWSI_BAUD_RATE_51DOT8   0x4c /* N=4, M=9  */
   92 #define TWSI_BAUD_RATE_99DOT7   0x66 /* N=6, M=12 */
   93 
   94 #define TWSI_SOFT_RESET         0x1c
   95 
   96 #define TWSI_DEBUG
   97 #undef TWSI_DEBUG
   98 
   99 #ifdef  TWSI_DEBUG
  100 #define debugf(fmt, args...) do { printf("%s(): ", __func__); printf(fmt,##args); } while (0)
  101 #else
  102 #define debugf(fmt, args...)
  103 #endif
  104 
  105 struct mv_twsi_softc {
  106         device_t        dev;
  107         struct resource *res[1];        /* SYS_RES_MEMORY */
  108         struct mtx      mutex;
  109         device_t        iicbus;
  110 };
  111 
  112 static int mv_twsi_probe(device_t);
  113 static int mv_twsi_attach(device_t);
  114 static int mv_twsi_detach(device_t);
  115 
  116 static int mv_twsi_reset(device_t dev, u_char speed, u_char addr,
  117     u_char *oldaddr);
  118 static int mv_twsi_repeated_start(device_t dev, u_char slave, int timeout);
  119 static int mv_twsi_start(device_t dev, u_char slave, int timeout);
  120 static int mv_twsi_stop(device_t dev);
  121 static int mv_twsi_read(device_t dev, char *buf, int len, int *read, int last,
  122     int delay);
  123 static int mv_twsi_write(device_t dev, const char *buf, int len, int *sent,
  124     int timeout);
  125 
  126 static struct resource_spec res_spec[] = {
  127         { SYS_RES_MEMORY, 0, RF_ACTIVE },
  128         { -1, 0 }
  129 };
  130 
  131 static device_method_t mv_twsi_methods[] = {
  132         /* device interface */
  133         DEVMETHOD(device_probe,         mv_twsi_probe),
  134         DEVMETHOD(device_attach,        mv_twsi_attach),
  135         DEVMETHOD(device_detach,        mv_twsi_detach),
  136 
  137         /* iicbus interface */
  138         DEVMETHOD(iicbus_callback, iicbus_null_callback),
  139         DEVMETHOD(iicbus_repeated_start, mv_twsi_repeated_start),
  140         DEVMETHOD(iicbus_start,         mv_twsi_start),
  141         DEVMETHOD(iicbus_stop,          mv_twsi_stop),
  142         DEVMETHOD(iicbus_write,         mv_twsi_write),
  143         DEVMETHOD(iicbus_read,          mv_twsi_read),
  144         DEVMETHOD(iicbus_reset,         mv_twsi_reset),
  145         DEVMETHOD(iicbus_transfer,      iicbus_transfer_gen),
  146         { 0, 0 }
  147 };
  148 
  149 static devclass_t mv_twsi_devclass;
  150 
  151 static driver_t mv_twsi_driver = {
  152         MV_TWSI_NAME,
  153         mv_twsi_methods,
  154         sizeof(struct mv_twsi_softc),
  155 };
  156 
  157 DRIVER_MODULE(twsi, simplebus, mv_twsi_driver, mv_twsi_devclass, 0, 0);
  158 DRIVER_MODULE(iicbus, twsi, iicbus_driver, iicbus_devclass, 0, 0);
  159 MODULE_DEPEND(twsi, iicbus, 1, 1, 1);
  160 
  161 static __inline uint32_t
  162 TWSI_READ(struct mv_twsi_softc *sc, bus_size_t off)
  163 {
  164 
  165         return (bus_read_4(sc->res[0], off));
  166 }
  167 
  168 static __inline void
  169 TWSI_WRITE(struct mv_twsi_softc *sc, bus_size_t off, uint32_t val)
  170 {
  171 
  172         bus_write_4(sc->res[0], off, val);
  173 }
  174 
  175 static __inline void
  176 twsi_control_clear(struct mv_twsi_softc *sc, uint32_t mask)
  177 {
  178         uint32_t val;
  179 
  180         val = TWSI_READ(sc, TWSI_CONTROL);
  181         val &= ~mask;
  182         TWSI_WRITE(sc, TWSI_CONTROL, val);
  183 }
  184 
  185 static __inline void
  186 twsi_control_set(struct mv_twsi_softc *sc, uint32_t mask)
  187 {
  188         uint32_t val;
  189 
  190         val = TWSI_READ(sc, TWSI_CONTROL);
  191         val |= mask;
  192         TWSI_WRITE(sc, TWSI_CONTROL, val);
  193 }
  194 
  195 static __inline void
  196 twsi_clear_iflg(struct mv_twsi_softc *sc)
  197 {
  198 
  199         DELAY(1000);
  200         twsi_control_clear(sc, TWSI_CONTROL_IFLG);
  201         DELAY(1000);
  202 }
  203 
  204 
  205 /*
  206  * timeout given in us
  207  * returns
  208  *   0 on sucessfull mask change
  209  *   non-zero on timeout
  210  */
  211 static int
  212 twsi_poll_ctrl(struct mv_twsi_softc *sc, int timeout, uint32_t mask)
  213 {
  214 
  215         timeout /= 10;
  216         while (!(TWSI_READ(sc, TWSI_CONTROL) & mask)) {
  217                 DELAY(10);
  218                 if (--timeout < 0)
  219                         return (timeout);
  220         }
  221         return (0);
  222 }
  223 
  224 
  225 /*
  226  * 'timeout' is given in us. Note also that timeout handling is not exact --
  227  * twsi_locked_start() total wait can be more than 2 x timeout
  228  * (twsi_poll_ctrl() is called twice). 'mask' can be either TWSI_STATUS_START
  229  * or TWSI_STATUS_RPTD_START
  230  */
  231 static int
  232 twsi_locked_start(device_t dev, struct mv_twsi_softc *sc, int32_t mask,
  233     u_char slave, int timeout)
  234 {
  235         int read_access, iflg_set = 0;
  236         uint32_t status;
  237 
  238         mtx_assert(&sc->mutex, MA_OWNED);
  239 
  240         if (mask == TWSI_STATUS_RPTD_START)
  241                 /* read IFLG to know if it should be cleared later; from NBSD */
  242                 iflg_set = TWSI_READ(sc, TWSI_CONTROL) & TWSI_CONTROL_IFLG;
  243 
  244         twsi_control_set(sc, TWSI_CONTROL_START);
  245 
  246         if (mask == TWSI_STATUS_RPTD_START && iflg_set) {
  247                 debugf("IFLG set, clearing\n");
  248                 twsi_clear_iflg(sc);
  249         }
  250 
  251         /*
  252          * Without this delay we timeout checking IFLG if the timeout is 0.
  253          * NBSD driver always waits here too.
  254          */
  255         DELAY(1000);
  256 
  257         if (twsi_poll_ctrl(sc, timeout, TWSI_CONTROL_IFLG)) {
  258                 debugf("timeout sending %sSTART condition\n",
  259                     mask == TWSI_STATUS_START ? "" : "repeated ");
  260                 return (IIC_ETIMEOUT);
  261         }
  262 
  263         status = TWSI_READ(sc, TWSI_STATUS);
  264         if (status != mask) {
  265                 debugf("wrong status (%02x) after sending %sSTART condition\n",
  266                     status, mask == TWSI_STATUS_START ? "" : "repeated ");
  267                 return (IIC_ESTATUS);
  268         }
  269 
  270         TWSI_WRITE(sc, TWSI_DATA, slave);
  271         DELAY(1000);
  272         twsi_clear_iflg(sc);
  273 
  274         if (twsi_poll_ctrl(sc, timeout, TWSI_CONTROL_IFLG)) {
  275                 debugf("timeout sending slave address\n");
  276                 return (IIC_ETIMEOUT);
  277         }
  278         
  279         read_access = (slave & 0x1) ? 1 : 0;
  280         status = TWSI_READ(sc, TWSI_STATUS);
  281         if (status != (read_access ?
  282             TWSI_STATUS_ADDR_R_ACK : TWSI_STATUS_ADDR_W_ACK)) {
  283                 debugf("no ACK (status: %02x) after sending slave address\n",
  284                     status);
  285                 return (IIC_ENOACK);
  286         }
  287 
  288         return (IIC_NOERR);
  289 }
  290 
  291 static int
  292 mv_twsi_probe(device_t dev)
  293 {
  294 
  295         if (!ofw_bus_is_compatible(dev, "mrvl,twsi"))
  296                 return (ENXIO);
  297 
  298         device_set_desc(dev, "Marvell Integrated I2C Bus Controller");
  299         return (BUS_PROBE_DEFAULT);
  300 }
  301 
  302 static int
  303 mv_twsi_attach(device_t dev)
  304 {
  305         struct mv_twsi_softc *sc;
  306 
  307         sc = device_get_softc(dev);
  308         sc->dev = dev;
  309 
  310         mtx_init(&sc->mutex, device_get_nameunit(dev), MV_TWSI_NAME, MTX_DEF);
  311 
  312         /* Allocate IO resources */
  313         if (bus_alloc_resources(dev, res_spec, sc->res)) {
  314                 device_printf(dev, "could not allocate resources\n");
  315                 mv_twsi_detach(dev);
  316                 return (ENXIO);
  317         }
  318 
  319         sc->iicbus = device_add_child(dev, "iicbus", -1);
  320         if (sc->iicbus == NULL) {
  321                 device_printf(dev, "could not add iicbus child\n");
  322                 mv_twsi_detach(dev);
  323                 return (ENXIO);
  324         }
  325 
  326         bus_generic_attach(dev);
  327         return (0);
  328 }
  329 
  330 static int
  331 mv_twsi_detach(device_t dev)
  332 {
  333         struct mv_twsi_softc *sc;
  334         int rv;
  335 
  336         sc = device_get_softc(dev);
  337 
  338         if ((rv = bus_generic_detach(dev)) != 0)
  339                 return (rv);
  340 
  341         if (sc->iicbus != NULL)
  342                 if ((rv = device_delete_child(dev, sc->iicbus)) != 0)
  343                         return (rv);
  344 
  345         bus_release_resources(dev, res_spec, sc->res);
  346 
  347         mtx_destroy(&sc->mutex);
  348         return (0);
  349 }
  350 
  351 /*
  352  * Only slave mode supported, disregard [old]addr
  353  */
  354 static int
  355 mv_twsi_reset(device_t dev, u_char speed, u_char addr, u_char *oldaddr)
  356 {
  357         struct mv_twsi_softc *sc;
  358         uint32_t baud_rate;
  359 
  360         sc = device_get_softc(dev);
  361 
  362         switch (speed) {
  363         case IIC_SLOW:
  364                 baud_rate = TWSI_BAUD_RATE_51DOT8;
  365                 break;
  366         case IIC_FAST:
  367                 baud_rate = TWSI_BAUD_RATE_51DOT8;
  368                 break;
  369         case IIC_UNKNOWN:
  370         case IIC_FASTEST:
  371         default:
  372                 baud_rate = TWSI_BAUD_RATE_99DOT7;
  373                 break;
  374         }
  375 
  376         mtx_lock(&sc->mutex);
  377         TWSI_WRITE(sc, TWSI_SOFT_RESET, 0x0);
  378         DELAY(2000);
  379         TWSI_WRITE(sc, TWSI_BAUD_RATE, baud_rate);
  380         TWSI_WRITE(sc, TWSI_CONTROL, TWSI_CONTROL_TWSIEN | TWSI_CONTROL_ACK);
  381         DELAY(1000);
  382         mtx_unlock(&sc->mutex);
  383 
  384         return (0);
  385 }
  386 
  387 /*
  388  * timeout is given in us
  389  */
  390 static int
  391 mv_twsi_repeated_start(device_t dev, u_char slave, int timeout)
  392 {
  393         struct mv_twsi_softc *sc;
  394         int rv;
  395 
  396         sc = device_get_softc(dev);
  397 
  398         mtx_lock(&sc->mutex);
  399         rv = twsi_locked_start(dev, sc, TWSI_STATUS_RPTD_START, slave,
  400             timeout);
  401         mtx_unlock(&sc->mutex);
  402 
  403         if (rv) {
  404                 mv_twsi_stop(dev);
  405                 return (rv);
  406         } else
  407                 return (IIC_NOERR);
  408 }
  409 
  410 /*
  411  * timeout is given in us
  412  */
  413 static int
  414 mv_twsi_start(device_t dev, u_char slave, int timeout)
  415 {
  416         struct mv_twsi_softc *sc;
  417         int rv;
  418 
  419         sc = device_get_softc(dev);
  420 
  421         mtx_lock(&sc->mutex);
  422         rv = twsi_locked_start(dev, sc, TWSI_STATUS_START, slave, timeout);
  423         mtx_unlock(&sc->mutex);
  424 
  425         if (rv) {
  426                 mv_twsi_stop(dev);
  427                 return (rv);
  428         } else
  429                 return (IIC_NOERR);
  430 }
  431 
  432 static int
  433 mv_twsi_stop(device_t dev)
  434 {
  435         struct mv_twsi_softc *sc;
  436 
  437         sc = device_get_softc(dev);
  438 
  439         mtx_lock(&sc->mutex);
  440         twsi_control_set(sc, TWSI_CONTROL_STOP);
  441         DELAY(1000);
  442         twsi_clear_iflg(sc);
  443         mtx_unlock(&sc->mutex);
  444 
  445         return (IIC_NOERR);
  446 }
  447 
  448 static int
  449 mv_twsi_read(device_t dev, char *buf, int len, int *read, int last, int delay)
  450 {
  451         struct mv_twsi_softc *sc;
  452         uint32_t status;
  453         int last_byte, rv;
  454 
  455         sc = device_get_softc(dev);
  456 
  457         mtx_lock(&sc->mutex);
  458         *read = 0;
  459         while (*read < len) {
  460                 /*
  461                  * Check if we are reading last byte of the last buffer,
  462                  * do not send ACK then, per I2C specs
  463                  */
  464                 last_byte = ((*read == len - 1) && last) ? 1 : 0;
  465                 if (last_byte)
  466                         twsi_control_clear(sc, TWSI_CONTROL_ACK);
  467                 else
  468                         twsi_control_set(sc, TWSI_CONTROL_ACK);
  469 
  470                 DELAY (1000);
  471                 twsi_clear_iflg(sc);
  472 
  473                 if (twsi_poll_ctrl(sc, delay, TWSI_CONTROL_IFLG)) {
  474                         debugf("timeout reading data\n");
  475                         rv = IIC_ETIMEOUT;
  476                         goto out;
  477                 }
  478 
  479                 status = TWSI_READ(sc, TWSI_STATUS);
  480                 if (status != (last_byte ?
  481                     TWSI_STATUS_DATA_RD_NOACK : TWSI_STATUS_DATA_RD_ACK)) {
  482                         debugf("wrong status (%02x) while reading\n", status);
  483                         rv = IIC_ESTATUS;
  484                         goto out;
  485                 }
  486 
  487                 *buf++ = TWSI_READ(sc, TWSI_DATA);
  488                 (*read)++;
  489         }
  490         rv = IIC_NOERR;
  491 out:
  492         mtx_unlock(&sc->mutex);
  493         return (rv);
  494 }
  495 
  496 static int
  497 mv_twsi_write(device_t dev, const char *buf, int len, int *sent, int timeout)
  498 {
  499         struct mv_twsi_softc *sc;
  500         uint32_t status;
  501         int rv;
  502 
  503         sc = device_get_softc(dev);
  504 
  505         mtx_lock(&sc->mutex);
  506         *sent = 0;
  507         while (*sent < len) {
  508                 TWSI_WRITE(sc, TWSI_DATA, *buf++);
  509 
  510                 twsi_clear_iflg(sc);
  511                 if (twsi_poll_ctrl(sc, timeout, TWSI_CONTROL_IFLG)) {
  512                         debugf("timeout writing data\n");
  513                         rv = IIC_ETIMEOUT;
  514                         goto out;
  515                 }
  516 
  517                 status = TWSI_READ(sc, TWSI_STATUS);
  518                 if (status != TWSI_STATUS_DATA_WR_ACK) {
  519                         debugf("wrong status (%02x) while writing\n", status);
  520                         rv = IIC_ESTATUS;
  521                         goto out;
  522                 }
  523                 (*sent)++;
  524         }
  525         rv = IIC_NOERR;
  526 out:
  527         mtx_unlock(&sc->mutex);
  528         return (rv);
  529 }

Cache object: 0891ea897d66b322794011f7e6e0bd5d


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