pcf8591.c

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    1 /*-
    2  * SPDX-License-Identifier: BSD-2-Clause
    3  *
    4  * Copyright (c) Andriy Gapon
    5  *
    6  * Redistribution and use in source and binary forms, with or without
    7  * modification, are permitted provided that the following conditions
    8  * are met:
    9  * 1. Redistributions of source code must retain the above copyright
   10  *    notice, this list of conditions, and the following disclaimer.
   11  * 2. Redistributions in binary form must reproduce the above copyright
   12  *    notice, this list of conditions and the following disclaimer in the
   13  *    documentation and/or other materials provided with the distribution.
   14  *
   15  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
   16  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   17  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   18  * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE FOR
   19  * ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   20  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   21  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   22  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   23  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   24  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   25  * SUCH DAMAGE.
   26  *
   27  */
   28 
   29 #include <sys/cdefs.h>
   30 __FBSDID("$FreeBSD$");
   31 
   32 #include "opt_platform.h"
   33 
   34 #include <sys/param.h>
   35 #include <sys/bus.h>
   36 #include <sys/kernel.h>
   37 #include <sys/module.h>
   38 #include <sys/sysctl.h>
   39 #include <sys/systm.h>
   40 
   41 #include <machine/bus.h>
   42 
   43 #include <dev/iicbus/iicbus.h>
   44 #include <dev/iicbus/iiconf.h>
   45 
   46 #ifdef FDT
   47 #include <dev/ofw/ofw_bus.h>
   48 #include <dev/ofw/ofw_bus_subr.h>
   49 #endif
   50 
   51 /*
   52  * Driver for PCF8591 I2C 8-bit ADC and DAC.
   53  */
   54 #define CTRL_CH_SELECT_MASK                     0x03
   55 #define CTRL_AUTOINC_EN                         0x04
   56 #define CTRL_CH_CONFIG_MASK                     0x30
   57 #define         CTRL_CH_CONFIG_4_SINGLE         0x00
   58 #define         CTRL_CH_CONFIG_3_DIFF           0x10
   59 #define         CTRL_CH_CONFIG_2_SINGLE_1_DIFF  0x20
   60 #define         CTRL_CH_CONFIG_2_DIFF           0x30
   61 #define CTRL_OUTPUT_EN                          0x40
   62 
   63 struct pcf8591_softc {
   64         device_t                sc_dev;
   65         int                     sc_ch_count;
   66         uint8_t                 sc_addr;
   67         uint8_t                 sc_cfg;
   68         uint8_t                 sc_output;
   69 };
   70 
   71 #ifdef FDT
   72 static struct ofw_compat_data compat_data[] = {
   73         { "nxp,pcf8591",        true },
   74         { NULL,                 false }
   75 };
   76 #endif
   77 
   78 static int
   79 pcf8591_set_config(device_t dev)
   80 {
   81 
   82         struct iic_msg msg;
   83         uint8_t data[2];
   84         struct pcf8591_softc *sc;
   85         int error;
   86 
   87         sc = device_get_softc(dev);
   88         data[0] = sc->sc_cfg;
   89         data[1] = sc->sc_output;
   90         msg.slave = sc->sc_addr;
   91         msg.flags = IIC_M_WR;
   92         msg.len = nitems(data);
   93         msg.buf = data;
   94 
   95         error = iicbus_transfer_excl(dev, &msg, 1, IIC_INTRWAIT);
   96         return (error);
   97 }
   98 
   99 static int
  100 pcf8591_get_reading(device_t dev, uint8_t *reading)
  101 {
  102         struct iic_msg msg;
  103         struct pcf8591_softc *sc;
  104         int error;
  105 
  106         sc = device_get_softc(dev);
  107 
  108         msg.slave = sc->sc_addr;
  109         msg.flags = IIC_M_RD;
  110         msg.len = 1;
  111         msg.buf = reading;
  112 
  113         error = iicbus_transfer_excl(dev, &msg, 1, IIC_INTRWAIT);
  114         return (error);
  115 }
  116 
  117 static int
  118 pcf8591_select_channel(device_t dev, int channel)
  119 {
  120         struct pcf8591_softc *sc;
  121         int error;
  122         uint8_t unused;
  123 
  124         sc = device_get_softc(dev);
  125         if (channel >= sc->sc_ch_count)
  126                 return (EINVAL);
  127         sc->sc_cfg &= ~CTRL_CH_SELECT_MASK;
  128         sc->sc_cfg += channel;
  129         error = pcf8591_set_config(dev);
  130         if (error != 0)
  131                 return (error);
  132 
  133         /*
  134          * The next read is still for the old channel,
  135          * so do it and discard.
  136          */
  137         error = pcf8591_get_reading(dev, &unused);
  138         return (error);
  139 }
  140 
  141 static int
  142 pcf8591_channel_sysctl(SYSCTL_HANDLER_ARGS)
  143 {
  144         device_t dev;
  145         int error, channel, val;
  146         uint8_t reading;
  147 
  148         dev = arg1;
  149         channel = arg2;
  150 
  151         if (req->oldptr != NULL) {
  152                 error = pcf8591_select_channel(dev, channel);
  153                 if (error != 0)
  154                         return (EIO);
  155                 error = pcf8591_get_reading(dev, &reading);
  156                 if (error != 0)
  157                         return (EIO);
  158                 val = reading;
  159         }
  160         error = sysctl_handle_int(oidp, &val, 0, req);
  161         return (error);
  162 }
  163 
  164 static void
  165 pcf8591_start(void *arg)
  166 {
  167         device_t dev;
  168         struct pcf8591_softc *sc;
  169         struct sysctl_ctx_list *ctx;
  170         struct sysctl_oid *tree_node;
  171         struct sysctl_oid_list *tree;
  172         struct sysctl_oid *inputs_node;
  173         struct sysctl_oid_list *inputs;
  174 
  175         sc = arg;
  176         dev = sc->sc_dev;
  177 
  178         /*
  179          * Set initial -- and, for the time being, fixed -- configuration.
  180          * Channel auto-incrementi is disabled, although it could be more
  181          * performant and precise for bulk channel queries.
  182          * The inputs are configured as four single channels.
  183          * The output is disabled.
  184          */
  185         sc->sc_cfg = 0;
  186         sc->sc_output = 0;
  187         sc->sc_ch_count = 4;
  188         (void)pcf8591_set_config(dev);
  189 
  190         ctx = device_get_sysctl_ctx(dev);
  191         tree_node = device_get_sysctl_tree(dev);
  192         tree = SYSCTL_CHILDREN(tree_node);
  193 
  194         inputs_node = SYSCTL_ADD_NODE(ctx, tree, OID_AUTO, "inputs",
  195             CTLTYPE_NODE, NULL, "Input channels");
  196         inputs = SYSCTL_CHILDREN(inputs_node);
  197         for (int i = 0; i < sc->sc_ch_count; i++) {
  198                 char buf[4];
  199 
  200                 snprintf(buf, sizeof(buf), "%d", i);
  201                 SYSCTL_ADD_PROC(ctx, inputs, OID_AUTO, buf,
  202                     CTLTYPE_INT | CTLFLAG_RD, dev, i,
  203                     pcf8591_channel_sysctl, "I", "Input level from 0 to 255 "
  204                     "(relative to Vref)");
  205         }
  206 }
  207 
  208 static int
  209 pcf8591_probe(device_t dev)
  210 {
  211 #ifdef FDT
  212         if (!ofw_bus_status_okay(dev))
  213                 return (ENXIO);
  214 #endif
  215         device_set_desc(dev, "PCF8591 8-bit ADC / DAC");
  216 #ifdef FDT
  217         if (ofw_bus_search_compatible(dev, compat_data)->ocd_data)
  218                 return (BUS_PROBE_GENERIC);
  219 #endif
  220         return (BUS_PROBE_NOWILDCARD);
  221 }
  222 
  223 static int
  224 pcf8591_attach(device_t dev)
  225 {
  226         struct pcf8591_softc *sc;
  227 
  228         sc = device_get_softc(dev);
  229         sc->sc_dev = dev;
  230         sc->sc_addr = iicbus_get_addr(dev);
  231 
  232         /*
  233          * We have to wait until interrupts are enabled.  Usually I2C read
  234          * and write only works when the interrupts are available.
  235          */
  236         config_intrhook_oneshot(pcf8591_start, sc);
  237         return (0);
  238 }
  239 
  240 static int
  241 pcf8591_detach(device_t dev)
  242 {
  243         return (0);
  244 }
  245 
  246 static device_method_t  pcf8591_methods[] = {
  247         /* Device interface */
  248         DEVMETHOD(device_probe,         pcf8591_probe),
  249         DEVMETHOD(device_attach,        pcf8591_attach),
  250         DEVMETHOD(device_detach,        pcf8591_detach),
  251 
  252         DEVMETHOD_END
  253 };
  254 
  255 static driver_t pcf8591_driver = {
  256         "pcf8591",
  257         pcf8591_methods,
  258         sizeof(struct pcf8591_softc)
  259 };
  260 
  261 DRIVER_MODULE(pcf8591, iicbus, pcf8591_driver, 0, 0);
  262 MODULE_DEPEND(pcf8591, iicbus, IICBUS_MINVER, IICBUS_PREFVER, IICBUS_MAXVER);
  263 MODULE_VERSION(pcf8591, 1);
  264 #ifdef FDT
  265 IICBUS_FDT_PNP_INFO(compat_data);
  266 #endif

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FreeBSD/Linux Kernel Cross Reference sys/dev/iicbus/pcf8591.c

FreeBSD/Linux Kernel Cross Reference
sys/dev/iicbus/pcf8591.c