MFC of r305114, r305115 and r305149:

Allow the use of control module extensions to cope with specific platform
features.

Add a driver for the AM335x bandgap sensor, an on-die temperature sensor
as part of the AM335x control module extension.

TI says that the bandgap sensor is not very accurate on AM335x, but in our
tests it seems to be a good reference for the SoC temperature.

TI details:
http://processors.wiki.ti.com/index.php/AM335x_Thermal_Considerations#Measuring_Case_Temperature

Sponsored by:	Rubicon Communications, LLC (Netgate)

4 files changed, 182 insertions, 1 deletions

diff --git a/sys/arm/ti/am335x/am335x_scm.c b/sys/arm/ti/am335x/am335x_scm.c
new file mode 100644
index 0000000..3d0dff4
--- /dev/null
+++ b/sys/arm/ti/am335x/am335x_scm.c
@@ -0,0 +1,169 @@
+/*-
+ * Copyright (c) 2016 Rubicon Communications, LLC (Netgate)
+ * 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 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 <sys/param.h>
+#include <sys/systm.h>
+#include <sys/bus.h>
+#include <sys/kernel.h>
+#include <sys/module.h>
+#include <sys/sysctl.h>
+
+#include <machine/bus.h>
+
+#include <arm/ti/am335x/am335x_scm.h>
+#include <arm/ti/ti_cpuid.h>
+#include <arm/ti/ti_scm.h>
+
+#define	TZ_ZEROC	2731
+
+struct am335x_scm_softc {
+	int			sc_last_temp;
+	struct sysctl_oid	*sc_temp_oid;
+};
+
+static int
+am335x_scm_temp_sysctl(SYSCTL_HANDLER_ARGS)
+{
+	device_t dev;
+	int i, temp;
+	struct am335x_scm_softc *sc;
+	uint32_t reg;
+
+	dev = (device_t)arg1;
+	sc = device_get_softc(dev);
+
+	/* Read the temperature and convert to Kelvin. */
+	for(i = 50; i > 0; i--) {
+		ti_scm_reg_read_4(SCM_BGAP_CTRL, &reg);
+		if ((reg & SCM_BGAP_EOCZ) == 0)
+			break;
+		DELAY(50);
+	}
+	if ((reg & SCM_BGAP_EOCZ) == 0) {
+		sc->sc_last_temp =
+		    (reg >> SCM_BGAP_TEMP_SHIFT) & SCM_BGAP_TEMP_MASK;
+		sc->sc_last_temp *= 10;
+	}
+	temp = sc->sc_last_temp + TZ_ZEROC;
+
+	return (sysctl_handle_int(oidp, &temp, 0, req));
+}
+
+static void
+am335x_scm_identify(driver_t *driver, device_t parent)
+{
+	device_t child;
+
+	/* AM335x only. */
+	if (ti_chip() != CHIP_AM335X)
+		return;
+
+	/* Make sure we attach only once. */
+	if (device_find_child(parent, "am335x_scm", -1) != NULL)
+		return;
+
+	child = device_add_child(parent, "am335x_scm", -1);
+	if (child == NULL)
+		device_printf(parent, "cannot add ti_scm child\n");
+}
+
+static int
+am335x_scm_probe(device_t dev)
+{
+
+	device_set_desc(dev, "AM335x Control Module Extension");
+
+	return (BUS_PROBE_DEFAULT);
+}
+
+static int
+am335x_scm_attach(device_t dev)
+{
+	struct am335x_scm_softc *sc;
+	struct sysctl_ctx_list *ctx;
+	struct sysctl_oid_list *tree;
+	uint32_t reg;
+
+	/* Set ADC to continous mode, clear output reset. */
+	reg = SCM_BGAP_CLRZ | SCM_BGAP_CONTCONV;
+	ti_scm_reg_write_4(SCM_BGAP_CTRL, reg);
+	/* Flush write. */
+	ti_scm_reg_read_4(SCM_BGAP_CTRL, &reg);
+	/* Start the ADC conversion. */
+	reg = SCM_BGAP_CLRZ | SCM_BGAP_CONTCONV | SCM_BGAP_SOC;
+	ti_scm_reg_write_4(SCM_BGAP_CTRL, reg);
+
+	/* Temperature sysctl. */
+	sc = device_get_softc(dev);
+        ctx = device_get_sysctl_ctx(dev);
+	tree = SYSCTL_CHILDREN(device_get_sysctl_tree(dev));
+	sc->sc_temp_oid = SYSCTL_ADD_PROC(ctx, tree, OID_AUTO,
+	    "temperature", CTLTYPE_INT | CTLFLAG_RD | CTLFLAG_MPSAFE,
+	    dev, 0, am335x_scm_temp_sysctl, "IK", "Current temperature");
+
+	return (0);
+}
+
+static int
+am335x_scm_detach(device_t dev)
+{
+	struct am335x_scm_softc *sc;
+
+	sc = device_get_softc(dev);
+
+	/* Remove temperature sysctl. */
+	if (sc->sc_temp_oid != NULL)
+		sysctl_remove_oid(sc->sc_temp_oid, 1, 0);
+
+	/* Stop the bandgap ADC. */
+	ti_scm_reg_write_4(SCM_BGAP_CTRL, SCM_BGAP_BGOFF);
+
+	return (0);
+}
+
+static device_method_t am335x_scm_methods[] = {
+	DEVMETHOD(device_identify,	am335x_scm_identify),
+	DEVMETHOD(device_probe,		am335x_scm_probe),
+	DEVMETHOD(device_attach,	am335x_scm_attach),
+	DEVMETHOD(device_detach,	am335x_scm_detach),
+
+	DEVMETHOD_END
+};
+
+static driver_t am335x_scm_driver = {
+	"am335x_scm",
+	am335x_scm_methods,
+	sizeof(struct am335x_scm_softc),
+};
+
+static devclass_t am335x_scm_devclass;
+
+DRIVER_MODULE(am335x_scm, ti_scm, am335x_scm_driver, am335x_scm_devclass, 0, 0);
+MODULE_VERSION(am335x_scm, 1);
+MODULE_DEPEND(am335x_scm, ti_scm, 1, 1, 1);
diff --git a/sys/arm/ti/am335x/am335x_scm.h b/sys/arm/ti/am335x/am335x_scm.h
index 4a01f82..6116be0 100644
--- a/sys/arm/ti/am335x/am335x_scm.h
+++ b/sys/arm/ti/am335x/am335x_scm.h
@@ -30,6 +30,14 @@
 
 /* AM335x-specific registers for control module (scm) */
 #define	SCM_CTRL_STATUS	0x40
+#define	SCM_BGAP_CTRL	0x448
+#define	SCM_BGAP_TEMP_MASK	0xff
+#define	SCM_BGAP_TEMP_SHIFT	8
+#define	SCM_BGAP_BGOFF		(1 << 6)
+#define	SCM_BGAP_SOC		(1 << 4)
+#define	SCM_BGAP_CLRZ		(1 << 3)
+#define	SCM_BGAP_CONTCONV	(1 << 2)
+#define	SCM_BGAP_EOCZ		(1 << 1)
 #define	SCM_USB_CTRL0	0x620
 #define	SCM_USB_STS0	0x624
 #define	SCM_USB_CTRL1	0x628
diff --git a/sys/arm/ti/am335x/files.am335x b/sys/arm/ti/am335x/files.am335x
index cc87659..a728211 100644
--- a/sys/arm/ti/am335x/files.am335x
+++ b/sys/arm/ti/am335x/files.am335x
@@ -13,6 +13,7 @@ arm/ti/am335x/am335x_pwmss.c		standard
 arm/ti/am335x/am335x_ehrpwm.c		standard
 arm/ti/am335x/am335x_ecap.c		standard
 arm/ti/am335x/am335x_rtc.c		optional	am335x_rtc
+arm/ti/am335x/am335x_scm.c		standard
 arm/ti/am335x/am335x_scm_padconf.c	standard
 arm/ti/am335x/am335x_usbss.c		optional	musb fdt
 arm/ti/am335x/am335x_musb.c		optional	musb fdt
diff --git a/sys/arm/ti/ti_scm.c b/sys/arm/ti/ti_scm.c
index 0752a21..ae36a9b 100644
--- a/sys/arm/ti/ti_scm.c
+++ b/sys/arm/ti/ti_scm.c
@@ -129,7 +129,10 @@ ti_scm_attach(device_t dev)
 
 	ti_scm_sc = sc;
 
-	return (0);
+	/* Attach platform extensions, if any. */
+	bus_generic_probe(dev);
+
+	return (bus_generic_attach(dev));
 }
 
 int