304 lines
8.4 KiB
C
304 lines
8.4 KiB
C
/* $NetBSD: mpl115a.c,v 1.1 2013/09/08 14:59:42 rkujawa Exp $ */
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/*-
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* Copyright (c) 2013 The NetBSD Foundation, Inc.
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* All rights reserved.
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*
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* This code is derived from software contributed to The NetBSD Foundation
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* by Radoslaw Kujawa.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
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* ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
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* TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
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* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
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* BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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* POSSIBILITY OF SUCH DAMAGE.
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*/
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/*
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* Freescale MPL115A2 miniature digital barometer driver.
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*
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* This driver could be split into bus-indepented driver and I2C-specific
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* attachment, as SPI variant of this chip also exist.
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*/
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#include <sys/cdefs.h>
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__KERNEL_RCSID(0, "$NetBSD: mpl115a.c,v 1.1 2013/09/08 14:59:42 rkujawa Exp $");
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#include <sys/param.h>
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#include <sys/systm.h>
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#include <sys/device.h>
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#include <sys/kernel.h>
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#include <sys/mutex.h>
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#include <sys/endian.h>
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#include <sys/bus.h>
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#include <dev/i2c/i2cvar.h>
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#include <dev/sysmon/sysmonvar.h>
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#include <dev/i2c/mpl115areg.h>
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#define MPL115A_DEBUG 1
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struct mpl115a_softc {
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device_t sc_dev;
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i2c_tag_t sc_tag;
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i2c_addr_t sc_addr;
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/* raw coefficients */
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int16_t sc_a0;
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int16_t sc_b1;
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int16_t sc_b2;
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int16_t sc_c12;
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/* envsys(4) stuff */
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struct sysmon_envsys *sc_sme;
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envsys_data_t sc_sensor;
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kmutex_t sc_lock;
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};
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static int mpl115a_match(device_t, cfdata_t, void *);
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static void mpl115a_attach(device_t, device_t, void *);
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static uint8_t mpl115a_reg_read_1(struct mpl115a_softc *sc, uint8_t);
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static void mpl115a_reg_write_1(struct mpl115a_softc *sc, uint8_t, uint8_t);
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static void mpl115a_load_coeffs(struct mpl115a_softc *sc);
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static uint16_t mpl115a_make_coeff(uint8_t msb, uint8_t lsb);
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static uint32_t mpl115a_pressure(struct mpl115a_softc *sc);
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static uint32_t mpl115a_calc(struct mpl115a_softc *sc, uint16_t padc, uint16_t tadc) ;
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static void mpl115a_envsys_register(struct mpl115a_softc *);
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static void mpl115a_envsys_refresh(struct sysmon_envsys *, envsys_data_t *);
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CFATTACH_DECL_NEW(mpl115a, sizeof (struct mpl115a_softc),
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mpl115a_match, mpl115a_attach, NULL, NULL);
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static int
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mpl115a_match(device_t parent, cfdata_t cf, void *aux)
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{
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struct i2c_attach_args *ia = aux;
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if (ia->ia_addr == MPL115A_ADDR)
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return 1;
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return 0;
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}
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static void
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mpl115a_attach(device_t parent, device_t self, void *aux)
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{
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struct mpl115a_softc *sc = device_private(self);
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struct i2c_attach_args *ia = aux;
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sc->sc_dev = self;
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sc->sc_addr = ia->ia_addr;
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sc->sc_tag = ia->ia_tag;
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aprint_normal(": Freescale MPL115A2 Pressure Sensor\n");
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/* Since coefficients do not change load them once. */
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mpl115a_load_coeffs(sc);
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mpl115a_pressure(sc);
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mutex_init(&sc->sc_lock, MUTEX_DEFAULT, IPL_NONE);
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mpl115a_envsys_register(sc);
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}
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/* Construct a coefficients from MSB and LSB bytes. */
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static uint16_t
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mpl115a_make_coeff(uint8_t msb, uint8_t lsb)
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{
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uint16_t rv;
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rv = le16toh((msb << 8) | lsb);
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#ifdef MPL115A_DEBUG
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aprint_normal("msb %x, lsb %x, ret val %x\n", msb, lsb, rv);
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#endif /* MPL115A_DEBUG */
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return rv;
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}
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static void
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mpl115a_load_coeffs(struct mpl115a_softc *sc)
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{
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sc->sc_a0 = mpl115a_make_coeff(mpl115a_reg_read_1(sc, MPL115A_A0_MSB),
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mpl115a_reg_read_1(sc, MPL115A_A0_LSB));
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sc->sc_b1 = mpl115a_make_coeff(mpl115a_reg_read_1(sc, MPL115A_B1_MSB),
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mpl115a_reg_read_1(sc, MPL115A_B1_LSB));
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sc->sc_b2 = mpl115a_make_coeff(mpl115a_reg_read_1(sc, MPL115A_B2_MSB),
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mpl115a_reg_read_1(sc, MPL115A_B2_LSB));
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sc->sc_c12 = mpl115a_make_coeff(mpl115a_reg_read_1(sc, MPL115A_C12_MSB),
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mpl115a_reg_read_1(sc, MPL115A_C12_LSB));
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}
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static void
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mpl115a_reg_write_1(struct mpl115a_softc *sc, uint8_t reg, uint8_t val)
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{
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if (iic_acquire_bus(sc->sc_tag, I2C_F_POLL) != 0) {
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aprint_error_dev(sc->sc_dev, "cannot acquire bus for write\n");
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return;
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}
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if (iic_exec(sc->sc_tag, I2C_OP_WRITE_WITH_STOP, sc->sc_addr, ®, 1,
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&val, 1, I2C_F_POLL)) {
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aprint_error_dev(sc->sc_dev, "cannot execute write\n");
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}
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iic_release_bus(sc->sc_tag, I2C_F_POLL);
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}
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static uint8_t
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mpl115a_reg_read_1(struct mpl115a_softc *sc, uint8_t reg)
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{
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uint8_t rv, wbuf[2];
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if (iic_acquire_bus(sc->sc_tag, I2C_F_POLL) != 0) {
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#ifdef MPL115A_DEBUG
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aprint_error_dev(sc->sc_dev, "cannot acquire bus for read\n");
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#endif /* MPL115A_DEBUG */
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return 0;
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}
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wbuf[0] = reg;
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if (iic_exec(sc->sc_tag, I2C_OP_READ_WITH_STOP, sc->sc_addr, wbuf,
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1, &rv, 1, I2C_F_POLL)) {
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aprint_error_dev(sc->sc_dev, "cannot execute read\n");
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iic_release_bus(sc->sc_tag, I2C_F_POLL);
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return 0;
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}
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iic_release_bus(sc->sc_tag, I2C_F_POLL);
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return rv;
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}
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/* Get pressure in pascals. */
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static uint32_t
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mpl115a_pressure(struct mpl115a_softc *sc)
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{
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uint32_t rv;
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uint16_t padc, tadc;
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rv = 0;
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mpl115a_reg_write_1(sc, MPL115A_CONVERT, 1);
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delay(20); /* even 3 should be enough */
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padc = mpl115a_make_coeff(mpl115a_reg_read_1(sc, MPL115A_PADC_MSB),
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mpl115a_reg_read_1(sc, MPL115A_PADC_LSB)); /* XXX, this fails */
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padc = mpl115a_make_coeff(mpl115a_reg_read_1(sc, MPL115A_PADC_MSB),
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mpl115a_reg_read_1(sc, MPL115A_PADC_LSB));
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tadc = mpl115a_make_coeff(mpl115a_reg_read_1(sc, MPL115A_TADC_MSB),
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mpl115a_reg_read_1(sc, MPL115A_TADC_LSB));
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#ifdef MPL115A_DEBUG
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aprint_normal_dev(sc->sc_dev, "padc %x, tadc %x\n", padc, tadc);
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#endif /* MPL115A_DEBUG */
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rv = mpl115a_calc(sc, padc, tadc);
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#ifdef MPL115A_DEBUG
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aprint_normal_dev(sc->sc_dev, "%d Pa\n", rv);
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#endif /* MPL115A_DEBUG */
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return rv;
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}
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/* The following calculation routine was suggested by Matt Thomas. */
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static uint32_t
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mpl115a_calc(struct mpl115a_softc *sc, uint16_t padc, uint16_t tadc)
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{
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int32_t fp_a0, fp_b1, fp_b2, fp_c12, fp_padc, fp_tadc;
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int32_t c12x2, a1, a1x2, y1, a2x2, pcomp;
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uint32_t pre_kpa1, pre_kpa2, pa;
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/* convert coefficients to common fixed point format */
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fp_a0 = sc->sc_a0 << 13; /* 12.3 -> 15.16 */
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fp_b1 = sc->sc_b1 << 3; /* 2.13 -> 15.16 */
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fp_b2 = sc->sc_b2 << 2; /* 1.14 -> 15.16 */
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fp_c12 = sc->sc_c12 >> 2; /* 0.22 */
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fp_padc = padc >> 6;
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fp_tadc = tadc >> 6;
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c12x2 = (fp_c12 * fp_tadc + 0x3f) >> 6;
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a1 = fp_b1 + c12x2;
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a1x2 = a1 * fp_padc;
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y1 = fp_a0 + a1x2;
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a2x2 = fp_b2 * fp_tadc;
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pcomp = y1 + a2x2;
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/* pre_kpa has 16 fractional digits so it's accurate to 1/65536 kPa */
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pre_kpa1 = pcomp * (115 - 50);
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pre_kpa2 = pre_kpa1 / 1023 + (50 << 16);
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/* but the real accuracy of the sensor is around +/- 1 kPa... */
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pa = ((pre_kpa2 + 32768) >> 16) * 1000;
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return pa;
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}
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static void
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mpl115a_envsys_register(struct mpl115a_softc *sc)
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{
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sc->sc_sme = sysmon_envsys_create();
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strlcpy(sc->sc_sensor.desc, "Absolute pressure",
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sizeof(sc->sc_sensor.desc));
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/* sc->sc_sensor.units = ENVSYS_SPRESSURE; */
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sc->sc_sensor.units = ENVSYS_INTEGER;
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sc->sc_sensor.state = ENVSYS_SINVALID;
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if (sysmon_envsys_sensor_attach(sc->sc_sme, &sc->sc_sensor)) {
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aprint_error_dev(sc->sc_dev,
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"error attaching sensor\n");
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return;
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}
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sc->sc_sme->sme_name = device_xname(sc->sc_dev);
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sc->sc_sme->sme_cookie = sc;
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sc->sc_sme->sme_refresh = mpl115a_envsys_refresh;
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if (sysmon_envsys_register(sc->sc_sme)) {
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aprint_error_dev(sc->sc_dev, "unable to register in sysmon\n");
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sysmon_envsys_destroy(sc->sc_sme);
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}
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}
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static void
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mpl115a_envsys_refresh(struct sysmon_envsys *sme, envsys_data_t *edata)
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{
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struct mpl115a_softc *sc = sme->sme_cookie;
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mutex_enter(&sc->sc_lock);
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edata->value_cur = mpl115a_pressure(sc);
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edata->state = ENVSYS_SVALID;
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mutex_exit(&sc->sc_lock);
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}
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