Rework pwmbus and pwmc so that each child will handle a single PWM channel.

Previously, there was a pwmc instance for each instance of pwm hardware
regardless of how many pwm channels that hardware supported.  Now there
will be a pwmc instance for each channel when the hardware supports
multiple channels.  With a separate instance for each channel, we can have
"named channels" in userland by making devfs alias entries in /dev/pwm.

These changes add support for ivars to pwmbus, and use an ivar to track the
channel number for each child.  It also adds support for hinted children.

In pwmc, the driver checks for a label hint, and if present, it's used to
create an alias for the cdev in /dev/pwm.  It's not anticipated that hints
will be heavily used, but it's easy to do and allows quick ad-hoc creation
of named channels from userland by using kenv to create hint.pwmc.N.label=
hints.  Upcoming changes will add FDT support, and most labels will
probably be specified that way.

3 files changed, 234 insertions, 29 deletions

diff --git a/sys/dev/pwm/pwmbus.c b/sys/dev/pwm/pwmbus.c
index 7039fde4b07d..2046baade085 100644
--- a/sys/dev/pwm/pwmbus.c
+++ b/sys/dev/pwm/pwmbus.c
@@ -37,28 +37,131 @@ __FBSDID("$FreeBSD$");
 #include <sys/conf.h>
 #include <sys/endian.h>
 #include <sys/kernel.h>
+#include <sys/malloc.h>
 #include <sys/module.h>
 
-#include <machine/bus.h>
+#include <dev/pwm/pwmbus.h>
 
 #include "pwmbus_if.h"
 
-struct pwmbus_channel_data {
-	int	reserved;
-	char	*name;
-};
-
 struct pwmbus_softc {
 	device_t	dev;
-	device_t	parent;
-
 	u_int		nchannels;
 };
 
+/*
+ * bus_if methods...
+ */
+
+static device_t
+pwmbus_add_child(device_t dev, u_int order, const char *name, int unit)
+{
+	device_t child;
+	struct pwmbus_ivars *ivars;
+
+	child = device_add_child_ordered(dev, order, name, unit);
+	if (child == NULL) 
+		return (child);
+
+	ivars = malloc(sizeof(struct pwmbus_ivars), M_DEVBUF, M_NOWAIT | M_ZERO);
+	if (ivars == NULL) {
+		device_delete_child(dev, child);
+		return (NULL);
+	}
+	device_set_ivars(child, ivars);
+
+	return (child);
+}
+
 static int
-pwmbus_probe(device_t dev)
+pwmbus_child_location_str(device_t dev, device_t child, char *buf, size_t blen)
+{
+	struct pwmbus_ivars *ivars;
+
+	ivars = device_get_ivars(child);
+	snprintf(buf, blen, "hwdev=%s channel=%u", 
+	    device_get_nameunit(device_get_parent(dev)), ivars->pi_channel);
+
+	return (0);
+}
+
+static int
+pwmbus_child_pnpinfo_str(device_t dev, device_t child, char *buf,
+    size_t buflen)
+{
+	*buf = '\0';
+	return (0);
+}
+
+static void
+pwmbus_hinted_child(device_t dev, const char *dname, int dunit)
+{
+	struct pwmbus_ivars *ivars;
+	device_t child;
+
+	child = pwmbus_add_child(dev, 0, dname, dunit);
+
+	/*
+	 * If there is a channel hint, use it.  Otherwise pi_channel was
+	 * initialized to zero, so that's the channel we'll use.
+	 */
+	ivars = device_get_ivars(child);
+	resource_int_value(dname, dunit, "channel", &ivars->pi_channel);
+}
+
+static int
+pwmbus_print_child(device_t dev, device_t child)
 {
+	struct pwmbus_ivars *ivars;
+	int rv;
+
+	ivars = device_get_ivars(child);
+
+	rv  = bus_print_child_header(dev, child);
+	rv += printf(" channel %u", ivars->pi_channel);
+	rv += bus_print_child_footer(dev, child);
+
+	return (rv);
+}
+
+static void
+pwmbus_probe_nomatch(device_t dev, device_t child)
+{
+	struct pwmbus_ivars *ivars;
+
+	ivars = device_get_ivars(child);
+	if (ivars != NULL)
+		device_printf(dev, "<unknown> on channel %u\n",
+		    ivars->pi_channel);
+
+	return;
+}
+
+static int
+pwmbus_read_ivar(device_t dev, device_t child, int which, uintptr_t *result)
+{
+	struct pwmbus_ivars *ivars;
 
+	ivars = device_get_ivars(child);
+
+	switch (which) {
+	case PWMBUS_IVAR_CHANNEL:
+		*(u_int *)result = ivars->pi_channel;
+		break;
+	default:
+		return (EINVAL);
+	}
+
+	return (0);
+}
+
+/*
+ * device_if methods...
+ */
+
+static int
+pwmbus_probe(device_t dev)
+{
 	device_set_desc(dev, "PWM bus");
 	return (BUS_PROBE_GENERIC);
 }
@@ -67,20 +170,33 @@ static int
 pwmbus_attach(device_t dev)
 {
 	struct pwmbus_softc *sc;
+	struct pwmbus_ivars *ivars;
+	device_t child, parent;
+	u_int chan;
 
 	sc = device_get_softc(dev);
 	sc->dev = dev;
-	sc->parent = device_get_parent(dev);
+	parent = device_get_parent(dev);
 
-	if (PWMBUS_CHANNEL_COUNT(sc->parent, &sc->nchannels) != 0 ||
+	if (PWMBUS_CHANNEL_COUNT(parent, &sc->nchannels) != 0 ||
 	    sc->nchannels == 0) {
 		device_printf(sc->dev, "No channels on parent %s\n",
-		    device_get_nameunit(sc->parent));
+		    device_get_nameunit(parent));
 		return (ENXIO);
 	}
 
-	device_add_child(sc->dev, "pwmc", -1);
+	/* Add a pwmc(4) child for each channel. */
+	for (chan = 0; chan < sc->nchannels; ++chan) {
+		if ((child = pwmbus_add_child(sc->dev, 0, "pwmc", -1)) == NULL) {
+			device_printf(dev, "failed to add pwmc child device "
+			    "for channel %u\n", chan);
+			continue;
+		}
+		ivars = device_get_ivars(child);
+		ivars->pi_channel = chan;
+	}
 
+	bus_enumerate_hinted_children(dev);
 	bus_generic_probe(dev);
 
 	return (bus_generic_attach(dev));
@@ -97,6 +213,10 @@ pwmbus_detach(device_t dev)
 	return (rv);
 }
 
+/*
+ * pwmbus_if methods...
+ */
+
 static int
 pwmbus_channel_config(device_t dev, u_int chan, u_int period, u_int duty)
 {
@@ -145,6 +265,15 @@ static device_method_t pwmbus_methods[] = {
 	DEVMETHOD(device_attach, pwmbus_attach),
 	DEVMETHOD(device_detach, pwmbus_detach),
 
+        /* bus_if */
+	DEVMETHOD(bus_add_child,		pwmbus_add_child),
+	DEVMETHOD(bus_child_location_str,	pwmbus_child_location_str),
+	DEVMETHOD(bus_child_pnpinfo_str,	pwmbus_child_pnpinfo_str),
+	DEVMETHOD(bus_hinted_child,		pwmbus_hinted_child),
+	DEVMETHOD(bus_print_child,		pwmbus_print_child),
+	DEVMETHOD(bus_probe_nomatch,		pwmbus_probe_nomatch),
+	DEVMETHOD(bus_read_ivar,		pwmbus_read_ivar),
+
         /* pwmbus_if  */
 	DEVMETHOD(pwmbus_channel_count,		pwmbus_channel_count),
 	DEVMETHOD(pwmbus_channel_config,	pwmbus_channel_config),
@@ -157,13 +286,13 @@ static device_method_t pwmbus_methods[] = {
 	DEVMETHOD_END
 };
 
-static driver_t pwmbus_driver = {
+driver_t pwmbus_driver = {
 	"pwmbus",
 	pwmbus_methods,
 	sizeof(struct pwmbus_softc),
 };
-static devclass_t pwmbus_devclass;
+devclass_t pwmbus_devclass;
 
 EARLY_DRIVER_MODULE(pwmbus, pwm, pwmbus_driver, pwmbus_devclass, 0, 0,
-  BUS_PASS_SUPPORTDEV + BUS_PASS_ORDER_MIDDLE);
+  BUS_PASS_BUS + BUS_PASS_ORDER_MIDDLE);
 MODULE_VERSION(pwmbus, 1);
diff --git a/sys/dev/pwm/pwmbus.h b/sys/dev/pwm/pwmbus.h
new file mode 100644
index 000000000000..ce37ad1ff966
--- /dev/null
+++ b/sys/dev/pwm/pwmbus.h
@@ -0,0 +1,62 @@
+/*-
+ * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
+ *
+ * Copyright (c) 2019 Ian Lepore <ian@FreeBSD.org>
+ *
+ * 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.
+ *
+ * $FreeBSD$
+ */
+
+#ifndef _PWMBUS_H_
+#define _PWMBUS_H_
+
+struct pwmbus_ivars {
+	u_int	pi_channel;
+};
+
+enum {
+	PWMBUS_IVAR_CHANNEL,	/* Channel used by child dev */
+};
+
+#define PWMBUS_ACCESSOR(A, B, T)					\
+static inline int							\
+pwmbus_get_ ## A(device_t dev, T *t)					\
+{									\
+	return BUS_READ_IVAR(device_get_parent(dev), dev,		\
+	    PWMBUS_IVAR_ ## B, (uintptr_t *) t);			\
+}									\
+static inline int							\
+pwmbus_set_ ## A(device_t dev, T t)					\
+{									\
+	return BUS_WRITE_IVAR(device_get_parent(dev), dev,		\
+	    PWMBUS_IVAR_ ## B, (uintptr_t) t);				\
+}
+
+PWMBUS_ACCESSOR(channel, CHANNEL, u_int)
+
+extern driver_t   pwmbus_driver;
+extern devclass_t pwmbus_devclass;
+extern driver_t   ofw_pwmbus_driver;
+extern devclass_t ofw_pwmbus_devclass;
+
+#endif /* _PWMBUS_H_ */
diff --git a/sys/dev/pwm/pwmc.c b/sys/dev/pwm/pwmc.c
index 18b60388a7bc..6b41a51997e4 100644
--- a/sys/dev/pwm/pwmc.c
+++ b/sys/dev/pwm/pwmc.c
@@ -37,14 +37,15 @@ __FBSDID("$FreeBSD$");
 #include <sys/module.h>
 #include <sys/time.h>
 
+#include <dev/pwm/pwmbus.h>
 #include <dev/pwm/pwmc.h>
 
 #include "pwmbus_if.h"
 
 struct pwmc_softc {
 	device_t	dev;
-	struct cdev	*pwm_dev;
-	char		name[32];
+	struct cdev	*cdev;
+	u_int		chan;
 };
 
 static int
@@ -68,19 +69,19 @@ pwm_ioctl(struct cdev *dev, u_long cmd, caddr_t data,
 		break;
 	case PWMSETSTATE:
 		bcopy(data, &state, sizeof(state));
-		rv = PWMBUS_CHANNEL_CONFIG(bus, state.channel,
+		rv = PWMBUS_CHANNEL_CONFIG(bus, sc->chan,
 		    state.period, state.duty);
 		if (rv == 0)
-			rv = PWMBUS_CHANNEL_ENABLE(bus, state.channel,
+			rv = PWMBUS_CHANNEL_ENABLE(bus, sc->chan,
 			    state.enable);
 		break;
 	case PWMGETSTATE:
 		bcopy(data, &state, sizeof(state));
-		rv = PWMBUS_CHANNEL_GET_CONFIG(bus, state.channel,
+		rv = PWMBUS_CHANNEL_GET_CONFIG(bus, sc->chan,
 		    &state.period, &state.duty);
 		if (rv != 0)
 			return (rv);
-		rv = PWMBUS_CHANNEL_IS_ENABLED(bus, state.channel,
+		rv = PWMBUS_CHANNEL_IS_ENABLED(bus, sc->chan,
 		    &state.enable);
 		if (rv != 0)
 			return (rv);
@@ -93,7 +94,7 @@ pwm_ioctl(struct cdev *dev, u_long cmd, caddr_t data,
 
 static struct cdevsw pwm_cdevsw = {
 	.d_version	= D_VERSION,
-	.d_name		= "pwm",
+	.d_name		= "pwmc",
 	.d_ioctl	= pwm_ioctl
 };
 
@@ -101,7 +102,7 @@ static int
 pwmc_probe(device_t dev)
 {
 
-	device_set_desc(dev, "PWM Controller");
+	device_set_desc(dev, "PWM Control");
 	return (BUS_PROBE_NOWILDCARD);
 }
 
@@ -110,22 +111,35 @@ pwmc_attach(device_t dev)
 {
 	struct pwmc_softc *sc;
 	struct make_dev_args args;
+	const char *label;
+	int error;
 
 	sc = device_get_softc(dev);
 	sc->dev = dev;
 
-	snprintf(sc->name, sizeof(sc->name), "pwmc%d", device_get_unit(dev));
+	if ((error = pwmbus_get_channel(dev, &sc->chan)) != 0)
+		return (error);
+
 	make_dev_args_init(&args);
 	args.mda_flags = MAKEDEV_CHECKNAME | MAKEDEV_WAITOK;
 	args.mda_devsw = &pwm_cdevsw;
 	args.mda_uid = UID_ROOT;
 	args.mda_gid = GID_OPERATOR;
-	args.mda_mode = 0600;
+	args.mda_mode = 0660;
 	args.mda_si_drv1 = sc;
-	if (make_dev_s(&args, &sc->pwm_dev, "%s", sc->name) != 0) {
+	error = make_dev_s(&args, &sc->cdev, "pwmc%d.%d",
+	    device_get_unit(device_get_parent(dev)), sc->chan);
+	if (error != 0) {
 		device_printf(dev, "Failed to make PWM device\n");
-		return (ENXIO);
+		return (error);
+	}
+
+	/* If there is a label hint, create an alias with that name. */
+	if (resource_string_value(device_get_name(dev), device_get_unit(dev),
+	    "label", &label) == 0) {
+		make_dev_alias(sc->cdev, "pwm/%s", label);
 	}
+
 	return (0);
 }
 
@@ -135,7 +149,7 @@ pwmc_detach(device_t dev)
 	struct pwmc_softc *sc;
  
 	sc = device_get_softc(dev);
-	destroy_dev(sc->pwm_dev);
+	destroy_dev(sc->cdev);
 
 	return (0);
 }