htu21.c

Go to the documentation of this file.

/*-
 * SPDX-License-Identifier: BSD-2-Clause
 *
 * Copyright (c) 2021 Andriy Gapon
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions, and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE FOR
 * ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 */
 
#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");
 
#include "opt_platform.h"
 
#include <sys/param.h>
#include <sys/bus.h>
#include <sys/kernel.h>
#include <sys/module.h>
#include <sys/sysctl.h>
#include <sys/systm.h>
 
#include <machine/bus.h>
 
#include <dev/iicbus/iicbus.h>
#include <dev/iicbus/iiconf.h>
 
#ifdef FDT
#include <dev/ofw/ofw_bus.h>
#include <dev/ofw/ofw_bus_subr.h>
#endif
 
/*
 * Driver for HTU21D and compatible temperature and humidity sensors.
 * Reference documents:
 * - Measurement Specialties HTU21D datasheet,
 * - Sensirion SHT21 datasheet,
 * - Silicon Labs Si7021 datasheet,
 * - HTU2X Serial Number Reading application note,
 * - Sensirion Electronic Identification Code (How to read-out the serial number
 *   of SHT2x) application note.
 */
#define HTU21_ADDR              0x40
 
#define HTU21_GET_TEMP          0xe3
#define HTU21_GET_HUM           0xe5
#define HTU21_GET_TEMP_NH       0xf3
#define HTU21_GET_HUM_NH        0xf5
#define HTU21_WRITE_CFG         0xe6
#define HTU21_READ_CFG          0xe7
#define HTU21_RESET             0xfe
 
#define HTU2x_SERIAL0_0         0xfa
#define HTU2x_SERIAL0_1         0x0f
#define HTU2x_SERIAL1_0         0xfc
#define HTU2x_SERIAL1_1         0xc9
 
struct htu21_softc {
        device_t                sc_dev;
        uint32_t                sc_addr;
        uint8_t                 sc_serial[8];
        int                     sc_errcount;
        bool                    sc_hold;
};
 
#ifdef FDT
static struct ofw_compat_data compat_data[] = {
        { "meas,htu21",         true },
        { NULL,                 false }
};
#endif
 
static uint8_t
calc_crc(uint16_t data)
{
        static const uint16_t polynomial = 0x3100;
        int i;
 
        for (i = 0; i < 16; i++) {
                int msb_neq = data & 0x8000;
 
                data <<= 1;
                if (msb_neq)
                        data ^= polynomial;
        }
        return (data >> 8);
}
 
static int
check_crc_16(const uint8_t *data, uint8_t expected)
{
        uint8_t crc;
 
        crc = calc_crc(((uint16_t)data[0] << 8) | data[1]);
        return (crc == expected);
}
 
static int
check_crc_8(const uint8_t data, uint8_t expected)
{
        uint8_t crc;
 
        crc = calc_crc(data);
        return (crc == expected);
}
 
static int
htu21_get_measurement(device_t dev, uint8_t cmd, uint8_t *data, int count)
{
 
        struct iic_msg msgs[2];
        struct htu21_softc *sc;
        int error;
 
        sc = device_get_softc(dev);
        msgs[0].slave = sc->sc_addr;
        msgs[0].flags = IIC_M_WR | IIC_M_NOSTOP;
        msgs[0].len = 1;
        msgs[0].buf = &cmd;
 
        msgs[1].slave = sc->sc_addr;
        msgs[1].flags = IIC_M_RD;
        msgs[1].len = count;
        msgs[1].buf = data;
 
        error = iicbus_transfer_excl(dev, msgs, nitems(msgs), IIC_INTRWAIT);
        return (error);
}
 
static int
htu21_get_measurement_nohold(device_t dev, uint8_t cmd,
    uint8_t *data, int count)
{
        struct iic_msg msgs[2];
        struct htu21_softc *sc;
        int error;
        int i;
 
        sc = device_get_softc(dev);
 
        msgs[0].slave = sc->sc_addr;
        msgs[0].flags = IIC_M_WR;
        msgs[0].len = 1;
        msgs[0].buf = &cmd;
 
        msgs[1].slave = sc->sc_addr;
        msgs[1].flags = IIC_M_RD;
        msgs[1].len = count;
        msgs[1].buf = data;
 
        error = iicbus_transfer_excl(dev, &msgs[0], 1, IIC_INTRWAIT);
        if (error != 0)
                return (error);
 
        for (i = 0; i < hz; i++) {
                error = iicbus_transfer_excl(dev, &msgs[1], 1, IIC_INTRWAIT);
                if (error == 0)
                        return (0);
                if (error != IIC_ENOACK)
                        break;
                pause("htu21", 1);
        }
        return (error);
}
 
static int
htu21_temp_sysctl(SYSCTL_HANDLER_ARGS)
{
        struct htu21_softc *sc;
        device_t dev;
        uint8_t raw_data[3];
        int error, temp;
 
        dev = arg1;
        sc = device_get_softc(dev);
 
        if (req->oldptr != NULL) {
                if (sc->sc_hold)
                        error = htu21_get_measurement(dev, HTU21_GET_TEMP,
                            raw_data, nitems(raw_data));
                else
                        error = htu21_get_measurement_nohold(dev,
                            HTU21_GET_TEMP_NH, raw_data, nitems(raw_data));
 
                if (error != 0) {
                        return (EIO);
                } else if (!check_crc_16(raw_data, raw_data[2])) {
                        temp = -1;
                        sc->sc_errcount++;
                } else {
                        temp = (((uint16_t)raw_data[0]) << 8) |
                            (raw_data[1] & 0xfc);
                        temp = ((temp * 17572) >> 16 ) + 27315 - 4685;
                }
        }
 
        error = sysctl_handle_int(oidp, &temp, 0, req);
        return (error);
}
 
static int
htu21_rh_sysctl(SYSCTL_HANDLER_ARGS)
{
        struct htu21_softc *sc;
        device_t dev;
        uint8_t raw_data[3];
        int error, rh;
 
        dev = arg1;
        sc = device_get_softc(dev);
 
        if (req->oldptr != NULL) {
                if (sc->sc_hold)
                        error = htu21_get_measurement(dev, HTU21_GET_HUM,
                            raw_data, nitems(raw_data));
                else
                        error = htu21_get_measurement_nohold(dev,
                            HTU21_GET_HUM_NH, raw_data, nitems(raw_data));
 
                if (error != 0) {
                        return (EIO);
                } else if (!check_crc_16(raw_data, raw_data[2])) {
                        rh = -1;
                        sc->sc_errcount++;
                } else {
                        rh = (((uint16_t)raw_data[0]) << 8) |
                            (raw_data[1] & 0xfc);
                        rh = ((rh * 12500) >> 16 ) - 600;
                }
        }
 
        error = sysctl_handle_int(oidp, &rh, 0, req);
        return (error);
}
 
static int
htu21_get_cfg(device_t dev, uint8_t *cfg)
{
 
        struct iic_msg msgs[2];
        struct htu21_softc *sc;
        uint8_t cmd;
        int error;
 
        sc = device_get_softc(dev);
        cmd = HTU21_READ_CFG;
        msgs[0].slave = sc->sc_addr;
        msgs[0].flags = IIC_M_WR | IIC_M_NOSTOP;
        msgs[0].len = 1;
        msgs[0].buf = &cmd;
 
        msgs[1].slave = sc->sc_addr;
        msgs[1].flags = IIC_M_RD;
        msgs[1].len = 1;
        msgs[1].buf = cfg;
 
        error = iicbus_transfer_excl(dev, msgs, nitems(msgs), IIC_INTRWAIT);
        return (error);
}
 
static int
htu21_set_cfg(device_t dev, uint8_t cfg)
{
 
        struct iic_msg msg;
        struct htu21_softc *sc;
        uint8_t buf[2];
        int error;
 
        sc = device_get_softc(dev);
        buf[0] = HTU21_WRITE_CFG;
        buf[1] = cfg;
        msg.slave = sc->sc_addr;
        msg.flags = IIC_M_WR;
        msg.len = 2;
        msg.buf = buf;
 
        error = iicbus_transfer_excl(dev, &msg, 1, IIC_INTRWAIT);
        return (error);
}
 
static int
htu21_heater_sysctl(SYSCTL_HANDLER_ARGS)
{
        device_t dev;
        uint8_t cfg;
        int error, heater;
 
        dev = arg1;
 
        if (req->oldptr != NULL) {
                error = htu21_get_cfg(dev, &cfg);
                if (error != 0)
                        return (EIO);
                heater = (cfg & 0x04) != 0;
        }
        error = sysctl_handle_int(oidp, &heater, 0, req);
        if (error != 0 || req->newptr == NULL)
                return (error);
 
        cfg &= ~0x04;
        cfg |= (heater > 0) << 2;
        error = htu21_set_cfg(dev, cfg);
        return (error != 0 ? EIO : 0);
}
 
static int
htu21_power_sysctl(SYSCTL_HANDLER_ARGS)
{
        device_t dev;
        uint8_t cfg;
        int error, power;
 
        dev = arg1;
 
        if (req->oldptr != NULL) {
                error = htu21_get_cfg(dev, &cfg);
                if (error != 0)
                        return (EIO);
                power = (cfg & 0x40) == 0;
        }
        error = sysctl_handle_int(oidp, &power, 0, req);
        return (error);
}
 
/*
 * May be incompatible with some chips like SHT21 and Si7021.
 */
static int
htu21_get_serial(device_t dev)
{
 
        struct iic_msg msgs[2];
        struct htu21_softc *sc;
        uint8_t data[8];
        uint8_t cmd[2];
        int error, cksum_err;
        int i;
 
        sc = device_get_softc(dev);
        cmd[0] = HTU2x_SERIAL0_0;
        cmd[1] = HTU2x_SERIAL0_1;
        msgs[0].slave = sc->sc_addr;
        msgs[0].flags = IIC_M_WR | IIC_M_NOSTOP;
        msgs[0].len = nitems(cmd);
        msgs[0].buf = cmd;
 
        msgs[1].slave = sc->sc_addr;
        msgs[1].flags = IIC_M_RD;
        msgs[1].len = nitems(data);
        msgs[1].buf = data;
 
        error = iicbus_transfer_excl(dev, msgs, nitems(msgs), IIC_INTRWAIT);
        if (error != 0)
                return (EIO);
 
        cksum_err = 0;
        for (i = 0; i < nitems(data); i += 2) {
                if (!check_crc_8(data[i], data[i + 1]))
                        cksum_err = EINVAL;
                sc->sc_serial[2 + i / 2] = data[i];
        }
 
        cmd[0] = HTU2x_SERIAL1_0;
        cmd[1] = HTU2x_SERIAL1_1;
        msgs[0].slave = sc->sc_addr;
        msgs[0].flags = IIC_M_WR | IIC_M_NOSTOP;
        msgs[0].len = nitems(cmd);
        msgs[0].buf = cmd;
 
        msgs[1].slave = sc->sc_addr;
        msgs[1].flags = IIC_M_RD;
        msgs[1].len = 6;
        msgs[1].buf = data;
 
        error = iicbus_transfer_excl(dev, msgs, nitems(msgs), IIC_INTRWAIT);
        if (error != 0)
                return (EIO);
 
        if (!check_crc_16(&data[0], data[2]))
                cksum_err = EINVAL;
        sc->sc_serial[6] = data[0];
        sc->sc_serial[7] = data[1];
 
        if (!check_crc_16(&data[3], data[5]))
                cksum_err = EINVAL;
        sc->sc_serial[0] = data[3];
        sc->sc_serial[1] = data[4];
 
        return (cksum_err);
}
 
static void
htu21_start(void *arg)
{
        device_t dev;
        struct htu21_softc *sc;
        struct sysctl_ctx_list *ctx;
        struct sysctl_oid *tree_node;
        struct sysctl_oid_list *tree;
        int error;
 
        sc = arg;
        dev = sc->sc_dev;
 
        for (int i = 0; i < 5; i++) {
                error = htu21_get_serial(dev);
                if (error == 0)
                        break;
        }
        if (error != EIO) {
                device_printf(dev, "serial number: %8D (checksum %scorrect)\n",
                    sc->sc_serial, ":", error == 0 ? "" : "in");
        } else {
                device_printf(dev, "failed to get serial number, err = %d\n",
                    error);
        }
 
        ctx = device_get_sysctl_ctx(dev);
        tree_node = device_get_sysctl_tree(dev);
        tree = SYSCTL_CHILDREN(tree_node);
 
        SYSCTL_ADD_PROC(ctx, tree, OID_AUTO, "temperature",
            CTLTYPE_INT | CTLFLAG_RD | CTLFLAG_MPSAFE, dev, 0,
            htu21_temp_sysctl, "IK2", "Current temperature");
        SYSCTL_ADD_PROC(ctx, tree, OID_AUTO, "humidity",
            CTLTYPE_INT | CTLFLAG_RD | CTLFLAG_MPSAFE, dev, 0,
            htu21_rh_sysctl, "I", "Relative humidity in 0.01%% units");
        SYSCTL_ADD_PROC(ctx, tree, OID_AUTO, "heater",
            CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_MPSAFE, dev, 0,
            htu21_heater_sysctl, "IU", "Enable built-in heater");
        SYSCTL_ADD_PROC(ctx, tree, OID_AUTO, "power",
            CTLTYPE_INT | CTLFLAG_RD | CTLFLAG_MPSAFE, dev, 0,
            htu21_power_sysctl, "IU", "If sensor's power is good");
        SYSCTL_ADD_BOOL(ctx, tree, OID_AUTO, "hold_bus",
            CTLFLAG_RW, &sc->sc_hold, 0,
            "Whether device should hold I2C bus while measuring");
        SYSCTL_ADD_INT(ctx, tree, OID_AUTO, "crc_errors",
            CTLTYPE_INT | CTLFLAG_RD | CTLFLAG_MPSAFE, &sc->sc_errcount, 0,
            "Number of checksum errors");
}
 
static int
htu21_probe(device_t dev)
{
        uint8_t addr;
        int rc;
 
#ifdef FDT
        if (!ofw_bus_status_okay(dev))
                return (ENXIO);
        if (ofw_bus_search_compatible(dev, compat_data)->ocd_data)
                rc = BUS_PROBE_GENERIC;
        else
#endif
                rc = BUS_PROBE_NOWILDCARD;
 
        addr = iicbus_get_addr(dev);
        if (addr != (HTU21_ADDR << 1)) {
                device_printf(dev, "non-standard slave address 0x%02x\n",
                    addr >> 1);
        }
 
        device_set_desc(dev, "HTU21 temperature and humidity sensor");
        return (rc);
}
 
static int
htu21_attach(device_t dev)
{
        struct htu21_softc *sc;
 
        sc = device_get_softc(dev);
        sc->sc_dev = dev;
        sc->sc_addr = iicbus_get_addr(dev);
 
        /*
         * We have to wait until interrupts are enabled.  Usually I2C read
         * and write only works when the interrupts are available.
         */
        config_intrhook_oneshot(htu21_start, sc);
        return (0);
}
 
static int
htu21_detach(device_t dev)
{
        return (0);
}
 
static device_method_t  htu21_methods[] = {
        /* Device interface */
        DEVMETHOD(device_probe,         htu21_probe),
        DEVMETHOD(device_attach,        htu21_attach),
        DEVMETHOD(device_detach,        htu21_detach),
 
        DEVMETHOD_END
};
 
static driver_t htu21_driver = {
        "htu21",
        htu21_methods,
        sizeof(struct htu21_softc)
};
 
static devclass_t htu21_devclass;
 
DRIVER_MODULE(htu21, iicbus, htu21_driver, htu21_devclass, 0, 0);
MODULE_DEPEND(htu21, iicbus, IICBUS_MINVER, IICBUS_PREFVER, IICBUS_MAXVER);
MODULE_VERSION(htu21, 1);
IICBUS_FDT_PNP_INFO(compat_data);