Add the lm75 i2c digital temperature sensor driver.

This driver supports the low and high precision models (9 and 11 bits) and
it will auto-detect the both variants.

The driver expose the temperature registers (actual temperature, shutdown
and hysteresys temperature) and also the configuration register.

It was tested on FDT systems: RPi, BBB and on non-FDT systems: AR71xx, with
both, hardware i2c controllers (when available) and gpioiic(4).

This provides a simple and cheap way for verifying the i2c bus on embedded
systems.

2 files changed, 575 insertions, 0 deletions

diff --git a/sys/conf/files b/sys/conf/files
index d11faa9..38afd9d 100644
--- a/sys/conf/files
+++ b/sys/conf/files
@@ -1444,6 +1444,7 @@ dev/iicbus/iiconf.c		optional iicbus
 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
diff --git a/sys/dev/iicbus/lm75.c b/sys/dev/iicbus/lm75.c
new file mode 100644
index 0000000..52ab159
--- /dev/null
+++ b/sys/dev/iicbus/lm75.c
@@ -0,0 +1,574 @@
+/*-
+ * Copyright (c) 2010 Andreas Tobler.
+ * Copyright (c) 2013-2014 Luiz Otavio O Souza <loos@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_TEST_PATTERN	0xa
+#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_LM75		1
+#define	HWTYPE_LM75A		2
+
+/* 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;
+};
+
+static 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)
+{
+	struct iic_msg msg[2] = {
+	    { addr, IIC_M_WR | IIC_M_NOSTOP, 1, &reg },
+	    { addr, IIC_M_RD, len, data },
+	};
+
+	if (iicbus_transfer(dev, msg, 2) != 0)
+		return (-1);
+
+	return (0);
+}
+
+static int
+lm75_write(device_t dev, uint32_t addr, uint8_t *data, size_t len)
+{
+	struct iic_msg msg[1] = {
+	    { addr, IIC_M_WR, len, data },
+	};
+
+	if (iicbus_transfer(dev, msg, 1) != 0)
+		return (-1);
+
+	return (0);
+}
+
+static int
+lm75_probe(device_t dev)
+{
+	struct lm75_softc *sc;
+
+	sc = device_get_softc(dev);
+	sc->sc_hwtype = HWTYPE_LM75;
+#ifdef FDT
+	if (!ofw_bus_is_compatible(dev, "national,lm75"))
+		return (ENXIO);
+#endif
+	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.  Usually I2C read
+	 * and write only works when the interrupts are available.
+	 */
+	if (config_intrhook_establish(&sc->enum_hook) != 0)
+		return (ENOMEM);
+
+	return (0);
+}
+
+static int
+lm75_type_detect(struct lm75_softc *sc)
+{
+	int i, lm75a;
+	uint8_t buf8;
+	uint32_t conf;
+
+	/* Save the contents of the configuration register. */
+	if (lm75_conf_read(sc) != 0)
+		return (-1);
+	conf = sc->sc_conf;
+
+	/*
+	 * Just write some pattern at configuration register so we can later
+	 * verify.  The test pattern should be pretty harmless.
+	 */
+	sc->sc_conf = LM75_TEST_PATTERN;
+	if (lm75_conf_write(sc) != 0)
+		return (-1);
+
+	/*
+	 * Read the configuration register again and check for our test
+	 * pattern.
+	 */
+	if (lm75_conf_read(sc) != 0)
+		return (-1);
+	if (sc->sc_conf != LM75_TEST_PATTERN)
+		return (-1);
+
+	/*
+	 * Read from nonexistent registers (0x4 ~ 0x6).
+	 * LM75A always return 0xff for nonexistent registers.
+	 * LM75 will return the last read value - our test pattern written to
+	 * configuration register.
+	 */
+	lm75a = 0;
+	for (i = 4; i <= 6; i++) {
+		if (lm75_read(sc->sc_dev, sc->sc_addr, i, &buf8, 1) < 0)
+			return (-1);
+		if (buf8 != LM75_TEST_PATTERN && buf8 != 0xff)
+			return (-1);
+		if (buf8 == 0xff)
+			lm75a++;
+	}
+	if (lm75a == 3)
+		sc->sc_hwtype = HWTYPE_LM75A;
+
+	/* Restore the configuration register. */
+	sc->sc_conf = conf;
+	if (lm75_conf_write(sc) != 0)
+		return (-1);
+
+	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);
+
+	/*
+	 * Detect the kind of chip we are attaching to.
+	 * This may not work for LM75 clones.
+	 */
+	if (lm75_type_detect(sc) != 0) {
+		device_printf(dev, "cannot read from sensor.\n");
+		return;
+	}
+	if (sc->sc_hwtype == HWTYPE_LM75A)
+		device_printf(dev,
+		    "LM75A type sensor detected (11bits resolution).\n");
+
+	/* 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 an 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 = (device_t)arg1;
+	reg = (uint8_t)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 = (device_t)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 = (device_t)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 = (device_t)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 = (device_t)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);
+}