[patch] LM75 kernel driver
Luiz Otavio O Souza
loos.br at gmail.com
Mon Mar 10 17:50:21 UTC 2014
On Fri, Nov 29, 2013 at 5:28 PM, Luiz Otavio O Souza wrote:
> Hi,
>
> I've written a kernel driver for lm75 (i2c temperature sensor).
>
> It's a very simple, convenient and cheap way to verify an i2c bus.
>
> This driver provides full control of the lm75 registers (configuration bits, over temperature and hysteresis settings) and so provides basic read and write test abilities.
>
> The high resolution version (lm75b - 11 bits) isn't supported ATM, but i have plans to do so.
The high resolution version (lm75[a/b]) is now tested and supported.
This new version is tested on RSPRO (with gpioiic(4)), on BBB and RPi
using both, gpioiic(4) and embedded i2c controllers.
It can be used together with snmp_lm75
(http://lists.freebsd.org/pipermail/freebsd-embedded/2014-March/002281.html)
to export the lm75 temperature via SNMP, it's use is quite
straightforward.
The updated version is attached.
Luiz
>
> On my RPi i've added this to sys/boot/fdt/dts/rpi.dts:
>
> bsc0 {
>
> lm750 {
> compatible = "lm75";
> i2c-address = <0x96>;
> };
>
> lm751 {
> compatible = "lm75";
> i2c-address = <0x9e>;
> };
> };
>
> And 'device lm75' to RPI-B kernel file (after apply the attached patch).
>
> Here is the result:
>
> iichb0: <BCM2708/2835 BSC controller> mem 0x20205000-0x2020501f irq 61 on simplebus0
> iicbus1: <OFW I2C bus> on iichb0
> iic1: <I2C generic I/O> on iicbus1
> lm751: <LM75 temperature sensor> at addr 0x96 on iicbus1
> lm752: <LM75 temperature sensor> at addr 0x9e on iicbus1
>
> # sysctl dev.lm75.1
> dev.lm75.1.%desc: LM75 temperature sensor
> dev.lm75.1.%driver: lm75
> dev.lm75.1.%location: addr=0x96
> dev.lm75.1.%pnpinfo: name=lm750 compat=lm75
> dev.lm75.1.%parent: iicbus1
> dev.lm75.1.temperature: 30.0C
> dev.lm75.1.thyst: 75.0C
> dev.lm75.1.tos: 80.0C
> dev.lm75.1.conf.faults: 1
> dev.lm75.1.conf.mode: comparator
> dev.lm75.1.conf.polarity: active-low
> dev.lm75.1.conf.shutdown: 0
>
> # sysctl dev.lm75.2
> dev.lm75.2.%desc: LM75 temperature sensor
> dev.lm75.2.%driver: lm75
> dev.lm75.2.%location: addr=0x9e
> dev.lm75.2.%pnpinfo: name=lm751 compat=lm75
> dev.lm75.2.%parent: iicbus1
> dev.lm75.2.temperature: 29.5C
> dev.lm75.2.thyst: 60.0C
> dev.lm75.2.tos: 80.0C
> dev.lm75.2.conf.faults: 2
> dev.lm75.2.conf.mode: interrupt
> dev.lm75.2.conf.polarity: active-low
> dev.lm75.2.conf.shutdown: 0
>
>
> I hope this may be useful for someone else.
>
> Luiz
>
>
-------------- next part --------------
Index: sys/conf/files
===================================================================
--- sys/conf/files (revision 262860)
+++ sys/conf/files (working copy)
@@ -1443,6 +1443,7 @@
dev/iicbus/iicsmb.c optional iicsmb \
dependency "iicbus_if.h"
dev/iicbus/iicoc.c optional iicoc
+dev/iicbus/lm75.c optional lm75
dev/iicbus/pcf8563.c optional pcf8563
dev/iicbus/s35390a.c optional s35390a
dev/iir/iir.c optional iir
Index: sys/dev/iicbus/lm75.c
===================================================================
--- sys/dev/iicbus/lm75.c (revision 0)
+++ sys/dev/iicbus/lm75.c (working copy)
@@ -0,0 +1,557 @@
+/*-
+ * Copyright (c) 2010 Andreas Tobler.
+ * Copyright (c) 2013 Luiz Otavio O Souza <loos at freebsd.org>.
+ * All rights reserved.
+ *
+ * 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 ``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 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/endian.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/openfirm.h>
+#include <dev/ofw/ofw_bus.h>
+#include <dev/ofw/ofw_bus_subr.h>
+#endif
+
+/* LM75 registers. */
+#define LM75_TEMP 0x0
+#define LM75_CONF 0x1
+#define LM75_CONF_FSHIFT 3
+#define LM75_CONF_FAULT 0x18
+#define LM75_CONF_POL 0x04
+#define LM75_CONF_MODE 0x02
+#define LM75_CONF_SHUTD 0x01
+#define LM75_CONF_MASK 0x1f
+#define LM75_THYST 0x2
+#define LM75_TOS 0x3
+
+/* LM75 constants. */
+#define LM75_MIN_TEMP -55
+#define LM75_MAX_TEMP 125
+#define LM75_0500C 0x80
+#define LM75_0250C 0x40
+#define LM75_0125C 0x20
+#define LM75_MSB 0x8000
+#define LM75_NEG_BIT LM75_MSB
+#define TZ_ZEROC 2732
+
+/* LM75 supported models. */
+#define HWTYPE_NONE 0
+#define HWTYPE_LM75 1
+#define HWTYPE_LM75A 2
+
+#ifdef FDT
+static struct ofw_compat_data compat_data[] = {
+ { "freebsd,lm75", HWTYPE_LM75 },
+ { "freebsd,lm75a", HWTYPE_LM75A },
+ { NULL, HWTYPE_NONE },
+};
+#endif
+
+/* Regular bus attachment functions */
+static int lm75_probe(device_t);
+static int lm75_attach(device_t);
+
+struct lm75_softc {
+ device_t sc_dev;
+ struct intr_config_hook enum_hook;
+ int32_t sc_hwtype;
+ uint32_t sc_addr;
+ uint32_t sc_conf;
+};
+
+int lm75_faults[4] = { 1, 2, 4, 6 };
+
+/* Utility functions */
+static int lm75_conf_read(struct lm75_softc *);
+static int lm75_conf_write(struct lm75_softc *);
+static int lm75_temp_read(struct lm75_softc *, uint8_t, int *);
+static int lm75_temp_write(struct lm75_softc *, uint8_t, int);
+static void lm75_start(void *);
+static int lm75_read(device_t, uint32_t, uint8_t, uint8_t *, size_t);
+static int lm75_write(device_t, uint32_t, uint8_t *, size_t);
+static int lm75_str_mode(char *);
+static int lm75_str_pol(char *);
+static int lm75_temp_sysctl(SYSCTL_HANDLER_ARGS);
+static int lm75_faults_sysctl(SYSCTL_HANDLER_ARGS);
+static int lm75_mode_sysctl(SYSCTL_HANDLER_ARGS);
+static int lm75_pol_sysctl(SYSCTL_HANDLER_ARGS);
+static int lm75_shutdown_sysctl(SYSCTL_HANDLER_ARGS);
+
+static device_method_t lm75_methods[] = {
+ /* Device interface */
+ DEVMETHOD(device_probe, lm75_probe),
+ DEVMETHOD(device_attach, lm75_attach),
+
+ DEVMETHOD_END
+};
+
+static driver_t lm75_driver = {
+ "lm75",
+ lm75_methods,
+ sizeof(struct lm75_softc)
+};
+
+static devclass_t lm75_devclass;
+
+DRIVER_MODULE(lm75, iicbus, lm75_driver, lm75_devclass, 0, 0);
+
+static int
+lm75_read(device_t dev, uint32_t addr, uint8_t reg, uint8_t *data, size_t len)
+{
+ int try;
+
+ struct iic_msg msg[2] = {
+ { addr, IIC_M_WR | IIC_M_NOSTOP, 1, ® },
+ { addr, IIC_M_RD, len, data },
+ };
+
+ try = 0;
+ for (;;) {
+ if (iicbus_transfer(dev, msg, 2) != 0)
+ goto retry;
+
+ return (0);
+ retry:
+ if (++try > 5) {
+ device_printf(dev, "iicbus read failed\n");
+ return (-1);
+ }
+ pause("lm75_read", hz);
+ }
+}
+
+static int
+lm75_write(device_t dev, uint32_t addr, uint8_t *data, size_t len)
+{
+ int try;
+
+ struct iic_msg msg[1] = {
+ { addr, IIC_M_WR, len, data },
+ };
+
+ try = 0;
+ for (;;) {
+ if (iicbus_transfer(dev, msg, 1) != 0)
+ goto retry;
+
+ return (0);
+ retry:
+ if (++try > 5) {
+ device_printf(dev, "iicbus write failed\n");
+ return (-1);
+ }
+ pause("lm75_write", hz);
+ }
+}
+
+static int
+lm75_probe(device_t dev)
+{
+ int type;
+ struct lm75_softc *sc;
+
+ type = 0;
+ sc = device_get_softc(dev);
+#ifdef FDT
+ sc->sc_hwtype = ofw_bus_search_compatible(dev, compat_data)->ocd_data;
+ if (sc->sc_hwtype == HWTYPE_NONE)
+ return (ENXIO);
+#else
+ sc->sc_hwtype = HWTYPE_LM75;
+ if (resource_int_value(device_get_name(dev), device_get_unit(dev),
+ "lm75a", &type) == 0 && type)
+ sc->sc_hwtype = HWTYPE_LM75A;
+#endif
+
+ switch (sc->sc_hwtype) {
+ case HWTYPE_LM75A:
+ device_set_desc(dev, "LM75A temperature sensor");
+ break;
+ default:
+ device_set_desc(dev, "LM75 temperature sensor");
+ }
+
+ return (BUS_PROBE_GENERIC);
+}
+
+static int
+lm75_attach(device_t dev)
+{
+ struct lm75_softc *sc;
+
+ sc = device_get_softc(dev);
+ sc->sc_dev = dev;
+ sc->sc_addr = iicbus_get_addr(dev);
+
+ sc->enum_hook.ich_func = lm75_start;
+ sc->enum_hook.ich_arg = dev;
+
+ /*
+ * We have to wait until interrupts are enabled. I2C read and write
+ * only works if the interrupts are available.
+ */
+ if (config_intrhook_establish(&sc->enum_hook) != 0)
+ return (ENOMEM);
+
+ return (0);
+}
+
+static void
+lm75_start(void *xdev)
+{
+ device_t dev;
+ struct lm75_softc *sc;
+ struct sysctl_ctx_list *ctx;
+ struct sysctl_oid *tree_node;
+ struct sysctl_oid_list *tree;
+
+ dev = (device_t)xdev;
+ sc = device_get_softc(dev);
+ ctx = device_get_sysctl_ctx(dev);
+ tree_node = device_get_sysctl_tree(dev);
+ tree = SYSCTL_CHILDREN(tree_node);
+
+ config_intrhook_disestablish(&sc->enum_hook);
+
+ /* Read the configuration register. */
+ if (lm75_conf_read(sc) != 0) {
+ device_printf(dev, "cannot read the configuration register.\n");
+ return;
+ }
+
+ /* Temperature. */
+ SYSCTL_ADD_PROC(ctx, tree, OID_AUTO, "temperature",
+ CTLTYPE_INT | CTLFLAG_RD | CTLFLAG_MPSAFE, dev, LM75_TEMP,
+ lm75_temp_sysctl, "IK", "Current temperature");
+ SYSCTL_ADD_PROC(ctx, tree, OID_AUTO, "thyst",
+ CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_MPSAFE, dev, LM75_THYST,
+ lm75_temp_sysctl, "IK", "Hysteresis temperature");
+ SYSCTL_ADD_PROC(ctx, tree, OID_AUTO, "tos",
+ CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_MPSAFE, dev, LM75_TOS,
+ lm75_temp_sysctl, "IK", "Overtemperature");
+
+ /* Configuration parameters. */
+ SYSCTL_ADD_PROC(ctx, tree, OID_AUTO, "faults",
+ CTLFLAG_RW | CTLTYPE_UINT, dev, 0,
+ lm75_faults_sysctl, "IU", "LM75 fault queue");
+ SYSCTL_ADD_PROC(ctx, tree, OID_AUTO, "mode",
+ CTLFLAG_RW | CTLTYPE_STRING, dev, 0,
+ lm75_mode_sysctl, "A", "LM75 mode");
+ SYSCTL_ADD_PROC(ctx, tree, OID_AUTO, "polarity",
+ CTLFLAG_RW | CTLTYPE_STRING, dev, 0,
+ lm75_pol_sysctl, "A", "LM75 OS polarity");
+ SYSCTL_ADD_PROC(ctx, tree, OID_AUTO, "shutdown",
+ CTLFLAG_RW | CTLTYPE_UINT, dev, 0,
+ lm75_shutdown_sysctl, "IU", "LM75 shutdown");
+}
+
+static int
+lm75_conf_read(struct lm75_softc *sc)
+{
+ uint8_t buf8;
+
+ if (lm75_read(sc->sc_dev, sc->sc_addr, LM75_CONF, &buf8, 1) < 0)
+ return (-1);
+
+ sc->sc_conf = (uint32_t)buf8;
+
+ return (0);
+}
+
+static int
+lm75_conf_write(struct lm75_softc *sc)
+{
+ uint8_t buf8[2];
+
+ buf8[0] = LM75_CONF;
+ buf8[1] = (uint8_t)sc->sc_conf & LM75_CONF_MASK;
+
+ if (lm75_write(sc->sc_dev, sc->sc_addr, buf8, 2) < 0)
+ return (-1);
+
+ return (0);
+}
+
+static int
+lm75_temp_read(struct lm75_softc *sc, uint8_t reg, int *temp)
+{
+ uint8_t buf8[2];
+ uint16_t buf;
+ int t;
+
+ if (lm75_read(sc->sc_dev, sc->sc_addr, reg, buf8, 2) < 0)
+ return (-1);
+
+ buf = (buf8[0] << 8) | (buf8[1] & 0xff);
+
+ /*
+ * LM75 has a 9 bit ADC with resolution of 0.5 C per bit.
+ * LM75A has a 11 bit ADC with resolution of 0.125 C per bit.
+ * Temperature is stored with two's complement.
+ */
+ if (buf & LM75_NEG_BIT)
+ buf = ~buf + 1;
+ *temp = ((int16_t)buf >> 8) * 10;
+ t = 0;
+ if (sc->sc_hwtype == HWTYPE_LM75A) {
+ if (buf & LM75_0125C)
+ t += 125;
+ if (buf & LM75_0250C)
+ t += 250;
+ }
+ if (buf & LM75_0500C)
+ t += 500;
+ t /= 100;
+ *temp += t;
+ if (buf & LM75_NEG_BIT)
+ *temp = -(*temp);
+ *temp += TZ_ZEROC;
+
+ return (0);
+}
+
+static int
+lm75_temp_write(struct lm75_softc *sc, uint8_t reg, int temp)
+{
+ uint8_t buf8[3];
+ uint16_t buf;
+
+ if (temp > LM75_MAX_TEMP)
+ temp = LM75_MAX_TEMP;
+ if (temp < LM75_MIN_TEMP)
+ temp = LM75_MIN_TEMP;
+
+ buf = (uint16_t)temp;
+ buf <<= 8;
+
+ buf8[0] = reg;
+ buf8[1] = buf >> 8;
+ buf8[2] = buf & 0xff;
+
+ if (lm75_write(sc->sc_dev, sc->sc_addr, buf8, 3) < 0)
+ return (-1);
+
+ return (0);
+}
+
+static int
+lm75_str_mode(char *buf)
+{
+ int len, rtrn;
+
+ rtrn = -1;
+ len = strlen(buf);
+ if (len > 2 && strncasecmp("interrupt", buf, len) == 0)
+ rtrn = 1;
+ else if (len > 2 && strncasecmp("comparator", buf, len) == 0)
+ rtrn = 0;
+
+ return (rtrn);
+}
+
+static int
+lm75_str_pol(char *buf)
+{
+ int len, rtrn;
+
+ rtrn = -1;
+ len = strlen(buf);
+ if (len > 1 && strncasecmp("high", buf, len) == 0)
+ rtrn = 1;
+ else if (len > 1 && strncasecmp("low", buf, len) == 0)
+ rtrn = 0;
+ else if (len > 8 && strncasecmp("active-high", buf, len) == 0)
+ rtrn = 1;
+ else if (len > 8 && strncasecmp("active-low", buf, len) == 0)
+ rtrn = 0;
+
+ return (rtrn);
+}
+
+static int
+lm75_temp_sysctl(SYSCTL_HANDLER_ARGS)
+{
+ device_t dev;
+ int error, temp;
+ struct lm75_softc *sc;
+ uint8_t reg;
+
+ dev = arg1;
+ reg = arg2;
+ sc = device_get_softc(dev);
+
+ if (lm75_temp_read(sc, reg, &temp) != 0)
+ return (EIO);
+
+ error = sysctl_handle_int(oidp, &temp, 0, req);
+ if (error != 0 || req->newptr == NULL)
+ return (error);
+
+ if (lm75_temp_write(sc, reg, temp) != 0)
+ return (EIO);
+
+ return (error);
+}
+
+static int
+lm75_faults_sysctl(SYSCTL_HANDLER_ARGS)
+{
+ device_t dev;
+ int error, faults, i, newf, tmp;
+ struct lm75_softc *sc;
+
+ dev = arg1;
+ sc = device_get_softc(dev);
+ tmp = (sc->sc_conf & LM75_CONF_FAULT) >> LM75_CONF_FSHIFT;
+ if (tmp > nitems(lm75_faults))
+ tmp = nitems(lm75_faults);
+ faults = lm75_faults[tmp];
+
+ error = sysctl_handle_int(oidp, &faults, 0, req);
+ if (error != 0 || req->newptr == NULL)
+ return (error);
+
+ if (faults != lm75_faults[tmp]) {
+ newf = 0;
+ for (i = 0; i < nitems(lm75_faults); i++)
+ if (faults >= lm75_faults[i])
+ newf = i;
+ sc->sc_conf &= ~LM75_CONF_FAULT;
+ sc->sc_conf |= newf << LM75_CONF_FSHIFT;
+ if (lm75_conf_write(sc) != 0)
+ return (EIO);
+ }
+
+ return (error);
+}
+
+static int
+lm75_mode_sysctl(SYSCTL_HANDLER_ARGS)
+{
+ char buf[16];
+ device_t dev;
+ int error, mode, newm;
+ struct lm75_softc *sc;
+
+ dev = arg1;
+ sc = device_get_softc(dev);
+ if (sc->sc_conf & LM75_CONF_MODE) {
+ mode = 1;
+ strlcpy(buf, "interrupt", sizeof(buf));
+ } else {
+ mode = 0;
+ strlcpy(buf, "comparator", sizeof(buf));
+ }
+
+ error = sysctl_handle_string(oidp, buf, sizeof(buf), req);
+ if (error != 0 || req->newptr == NULL)
+ return (error);
+
+ newm = lm75_str_mode(buf);
+ if (newm != -1 && mode != newm) {
+ sc->sc_conf &= ~LM75_CONF_MODE;
+ if (newm == 1)
+ sc->sc_conf |= LM75_CONF_MODE;
+ if (lm75_conf_write(sc) != 0)
+ return (EIO);
+ }
+
+ return (error);
+}
+
+static int
+lm75_pol_sysctl(SYSCTL_HANDLER_ARGS)
+{
+ char buf[16];
+ device_t dev;
+ int error, newp, pol;
+ struct lm75_softc *sc;
+
+ dev = arg1;
+ sc = device_get_softc(dev);
+ if (sc->sc_conf & LM75_CONF_POL) {
+ pol = 1;
+ strlcpy(buf, "active-high", sizeof(buf));
+ } else {
+ pol = 0;
+ strlcpy(buf, "active-low", sizeof(buf));
+ }
+
+ error = sysctl_handle_string(oidp, buf, sizeof(buf), req);
+ if (error != 0 || req->newptr == NULL)
+ return (error);
+
+ newp = lm75_str_pol(buf);
+ if (newp != -1 && pol != newp) {
+ sc->sc_conf &= ~LM75_CONF_POL;
+ if (newp == 1)
+ sc->sc_conf |= LM75_CONF_POL;
+ if (lm75_conf_write(sc) != 0)
+ return (EIO);
+ }
+
+ return (error);
+}
+
+static int
+lm75_shutdown_sysctl(SYSCTL_HANDLER_ARGS)
+{
+ device_t dev;
+ int error, shutdown, tmp;
+ struct lm75_softc *sc;
+
+ dev = arg1;
+ sc = device_get_softc(dev);
+ tmp = shutdown = (sc->sc_conf & LM75_CONF_SHUTD) ? 1 : 0;
+
+ error = sysctl_handle_int(oidp, &shutdown, 0, req);
+ if (error != 0 || req->newptr == NULL)
+ return (error);
+
+ if (shutdown != tmp) {
+ sc->sc_conf &= ~LM75_CONF_SHUTD;
+ if (shutdown)
+ sc->sc_conf |= LM75_CONF_SHUTD;
+ if (lm75_conf_write(sc) != 0)
+ return (EIO);
+ }
+
+ return (error);
+}
Property changes on: sys/dev/iicbus/lm75.c
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+native
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Index: share/man/man4/Makefile
===================================================================
--- share/man/man4/Makefile (revision 262860)
+++ share/man/man4/Makefile (working copy)
@@ -223,6 +223,7 @@
lge.4 \
${_lindev.4} \
${_linux.4} \
+ lm75.4 \
lmc.4 \
lo.4 \
lp.4 \
Index: share/man/man4/lm75.4
===================================================================
--- share/man/man4/lm75.4 (revision 0)
+++ share/man/man4/lm75.4 (working copy)
@@ -0,0 +1,192 @@
+.\"
+.\" Copyright (c) 2014 Luiz Otavio O Souza <loos at freebsd.org>
+.\" All rights reserved.
+.\"
+.\" 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 ``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 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.
+.\"
+.\" $FreeBSD$
+.\"
+.Dd March 7, 2014
+.Dt LM75 4
+.Os
+.Sh NAME
+.Nm lm75
+.Nd lm75 i2c digital temperature sensor driver
+.Sh SYNOPSIS
+.Cd "device iic"
+.Cd "device iicbus"
+.Cd "device lm75"
+.Sh DESCRIPTION
+The
+.Nm
+driver provides access to sensor data and configuration over the
+.Xr iicbus 4 .
+.Pp
+It provides an easy and simple way to check the functionality of an i2c bus
+as it provides read and write access to the
+.Nm
+configuration register.
+.Pp
+The access to
+.Nm
+data is made via the
+.Xr sysctl 8
+interface:
+.Bd -literal
+dev.lm75.0.%desc: LM75A temperature sensor
+dev.lm75.0.%driver: lm75
+dev.lm75.0.%location: addr=0x49
+dev.lm75.0.%pnpinfo: name=lm750 compat=freebsd,lm75a
+dev.lm75.0.%parent: iicbus3
+dev.lm75.0.temperature: 27.1C
+dev.lm75.0.thyst: 75.0C
+dev.lm75.0.tos: 80.0C
+dev.lm75.0.faults: 1
+dev.lm75.0.mode: comparator
+dev.lm75.0.polarity: active-low
+dev.lm75.0.shutdown: 0
+.Ed
+.Bl -tag -width ".Va dev.lm75.%d.temperature"
+.It Va dev.lm75.%d.temperature
+Is the read-only value of the current temperature read by the sensor.
+.It Va dev.lm75.%d.thyst
+Sets the hysteresis temperature.
+Once the temperature get over the overtemperature shutdown value (tos)
+it need to drop bellow the hysteresis temperature to disable the output
+(interrupt) pin again.
+.It Va dev.lm75.%d.tos
+Sets the overtemperature shutdown value.
+Once the temperature get over this value the output pin will be enabled.
+The way the output (interrupt) pin works, depends on the mode.
+.It Va dev.lm75.%d.faults
+Is the number of faults that must occur consecutively to activate the
+interrupt (output) pin.
+It can be set to 1, 2, 4, and 6.
+.It Va dev.lm75.%d.mode
+Set the operation mode for the sensor interrupt pin.
+It can be set to 'comparator' (default) or 'interrupt'.
+.It Va dev.lm75.%d.polarity
+Set the polarity of the sensor interrupt pin.
+It can be set to 'active-low' (default) or 'active-high'.
+Please note that the output pin is an open-drain output and it needs a
+proper pull-up resistor to work.
+.It Va dev.lm75.%d.shutdown
+When set to '1' it shutdown the sensor.
+The temperature convertion stops but the sensor remains with its i2c bus
+active, i.e., it can be woken up by setting this option to '0' again.
+.El
+.Pp
+Please check the
+.Nm
+datasheet for more details.
+.Pp
+When used together with
+.Xr snmp_lm75 3
+it allows the monitoring of
+.Nm
+temperature data over SNMP.
+.Pp
+The
+.Nm
+driver supports both the low and the high resolution models.
+.Pp
+The low resolution model (lm75) provides a 9 bit output with the LSB
+representing 0.5C.
+.Pp
+The high resolution model (lm75a) provides an 11 bit output with the LSB
+representing 0.125C.
+.Pp
+On a
+.Xr device.hints 5
+based system, like
+.Li MIPS ,
+these values are configurable for the
+.Nm :
+.Bl -tag -width ".Va hint.lm75.%d.lm75a"
+.It Va hint.lm75.%d.at
+Is the
+.Xr iicbus 4
+you are attaching to.
+.It Va hint.lm75.%d.addr
+Is the
+.Nm
+i2c address on the
+.Xr iicbus 4 .
+.It Va hint.lm75.%d.lm75a
+When set to '1' enables the high resolution temperature reading for this
+sensor.
+.El
+.Pp
+On a
+.Xr FDT 4
+based system, like
+.Li ARM ,
+the DTS part for a
+.Nm
+device usually looks like:
+.Bd -literal
+i2c {
+
+ ...
+
+ lm750 {
+ compatible = "freebsd,lm75";
+ i2c-address = <0x48>;
+ };
+
+ lm751 {
+ compatible = "freebsd,lm75a";
+ i2c-address = <0x49>;
+ };
+};
+.Ed
+.Pp
+Where:
+.Bl -tag -width ".Va i2c-address"
+.It Va compatible
+Should be set to "freebsd,lm75" for the low resolution devices and
+"freebsd,lm75a" for the high resolution devices.
+.It Va i2c-address
+The
+.Va i2c-address
+property indicates which i2c address the
+.Nm
+is wired at.
+.Nm
+temperature sensors can be wired to 8 different address, allowing up to 8
+sensors on the same
+.Xr iicbus 4 .
+.El
+.Sh SEE ALSO
+.Xr snmp_lm75 3 ,
+.Xr fdt 4 ,
+.Xr iic 4 ,
+.Xr iicbus 4 ,
+.Xr sysctl 8
+.Sh HISTORY
+The
+.Nm
+driver first appeared in
+.Fx 11.0 .
+.Sh AUTHORS
+.An -nosplit
+The driver and this manual page was written by
+.An Luiz Otavio O Souza Aq loos at FreeBSD.org
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