linuxkpi: Add backlight support

Add backlight function to linuxkpi.
Graphics drivers expose the backlight of the panel directly so allow them to use the backlight subsystem so
user can use backlight(8) to configure them.

Reviewed by:	hselasky
Relnotes:	yes
Differential Revision:	The FreeBSD Foundation

sys/compat/linuxkpi/common/include/linux/backlight.h

@@ -0,0 +1,94 @@
+/*-
+ * Copyright (c) 2020 The FreeBSD Foundation
+ *
+ * This software was developed by Emmanuel Vadot under sponsorship
+ * from the FreeBSD Foundation.
+ *
+ * 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 _LINUX_BACKLIGHT_H_
+#define _LINUX_BACKLIGHT_H_
+
+#include <linux/notifier.h>
+
+struct backlight_device;
+
+enum backlight_type {
+	BACKLIGHT_RAW = 0,
+};
+
+struct backlight_properties {
+	int type;
+	int max_brightness;
+	int brightness;
+	int power;
+};
+
+enum backlight_notification {
+	BACKLIGHT_REGISTERED,
+	BACKLIGHT_UNREGISTERED,
+};
+
+enum backlight_update_reason {
+	BACKLIGHT_UPDATE_HOTKEY = 0
+};
+
+struct backlight_ops {
+	int options;
+#define	BL_CORE_SUSPENDRESUME   1
+	int (*update_status)(struct backlight_device *);
+	int (*get_brightness)(struct backlight_device *);
+};
+
+struct backlight_device {
+	const struct backlight_ops *ops;
+	struct backlight_properties props;
+	void *data;
+	struct device *dev;
+	char *name;
+};
+
+#define bl_get_data(bd) (bd)->data
+
+struct backlight_device *linux_backlight_device_register(const char *name,
+    struct device *dev, void *data, const struct backlight_ops *ops, struct backlight_properties *props);
+void linux_backlight_device_unregister(struct backlight_device *bd);
+#define	backlight_device_register(name, dev, data, ops, props)	\
+	linux_backlight_device_register(name, dev, data, ops, props)
+#define	backlight_device_unregister(bd)	linux_backlight_device_unregister(bd)
+
+static inline void
+backlight_update_status(struct backlight_device *bd)
+{
+	bd->ops->update_status(bd);
+}
+
+static inline void
+backlight_force_update(struct backlight_device *bd, int reason)
+{
+	bd->props.brightness = bd->ops->get_brightness(bd);
+}
+
+#endif	/* _LINUX_BACKLIGHT_H_ */

sys/compat/linuxkpi/common/include/linux/device.h

@@ -41,9 +41,11 @@
 #include <linux/module.h>
 #include <linux/workqueue.h>
 #include <linux/kdev_t.h>
+#include <linux/backlight.h>
 #include <asm/atomic.h>
 
 #include <sys/bus.h>
+#include <sys/backlight.h>
 
 struct device;
 struct fwnode_handle;
@@ -114,6 +116,8 @@ struct device {
 	unsigned int	irq_end;
 	const struct attribute_group **groups;
 	struct fwnode_handle *fwnode;
+	struct cdev	*backlight_dev;
+	struct backlight_device	*bd;
 
 	spinlock_t	devres_lock;
 	struct list_head devres_head;

sys/compat/linuxkpi/common/src/linux_kmod.c

@@ -31,4 +31,5 @@ __FBSDID("$FreeBSD$");
 #include <sys/module.h>
 
 MODULE_VERSION(linuxkpi, 1);
+MODULE_DEPEND(linuxkpi, backlight, 1, 1, 1);
 MODULE_DEPEND(linuxkpi, pci, 1, 1, 1);

sys/compat/linuxkpi/common/src/linux_pci.c

@@ -50,6 +50,7 @@ __FBSDID("$FreeBSD$");
 #include <dev/pci/pcivar.h>
 #include <dev/pci/pci_private.h>
 #include <dev/pci/pci_iov.h>
+#include <dev/backlight/backlight.h>
 
 #include <linux/kobject.h>
 #include <linux/device.h>
@@ -64,6 +65,10 @@ __FBSDID("$FreeBSD$");
 #include <linux/pci.h>
 #include <linux/compat.h>
 
+#include <linux/backlight.h>
+
+#include "backlight_if.h"
+
 static device_probe_t linux_pci_probe;
 static device_attach_t linux_pci_attach;
 static device_detach_t linux_pci_detach;
@@ -73,6 +78,9 @@ static device_shutdown_t linux_pci_shutdown;
 static pci_iov_init_t linux_pci_iov_init;
 static pci_iov_uninit_t linux_pci_iov_uninit;
 static pci_iov_add_vf_t linux_pci_iov_add_vf;
+static int linux_backlight_get_status(device_t dev, struct backlight_props *props);
+static int linux_backlight_update_status(device_t dev, struct backlight_props *props);
+static int linux_backlight_get_info(device_t dev, struct backlight_info *info);
 
 static device_method_t pci_methods[] = {
 	DEVMETHOD(device_probe, linux_pci_probe),
@@ -84,6 +92,11 @@ static device_method_t pci_methods[] = {
 	DEVMETHOD(pci_iov_init, linux_pci_iov_init),
 	DEVMETHOD(pci_iov_uninit, linux_pci_iov_uninit),
 	DEVMETHOD(pci_iov_add_vf, linux_pci_iov_add_vf),
+
+	/* backlight interface */
+	DEVMETHOD(backlight_update_status, linux_backlight_update_status),
+	DEVMETHOD(backlight_get_status, linux_backlight_get_status),
+	DEVMETHOD(backlight_get_info, linux_backlight_get_info),
 	DEVMETHOD_END
 };
 
@@ -951,3 +964,73 @@ linux_dma_pool_free(struct dma_pool *pool, void *vaddr, dma_addr_t dma_addr)
 
 	uma_zfree_arg(pool->pool_zone, obj, pool);
 }
+
+static int
+linux_backlight_get_status(device_t dev, struct backlight_props *props)
+{
+	struct pci_dev *pdev;
+
+	linux_set_current(curthread);
+	pdev = device_get_softc(dev);
+
+	props->brightness = pdev->dev.bd->props.brightness;
+	props->brightness = props->brightness * 100 / pdev->dev.bd->props.max_brightness;
+	props->nlevels = 0;
+
+	return (0);
+}
+
+static int
+linux_backlight_get_info(device_t dev, struct backlight_info *info)
+{
+	struct pci_dev *pdev;
+
+	linux_set_current(curthread);
+	pdev = device_get_softc(dev);
+
+	info->type = BACKLIGHT_TYPE_PANEL;
+	strlcpy(info->name, pdev->dev.bd->name, BACKLIGHTMAXNAMELENGTH);
+	return (0);
+}
+
+static int
+linux_backlight_update_status(device_t dev, struct backlight_props *props)
+{
+	struct pci_dev *pdev;
+
+	linux_set_current(curthread);
+	pdev = device_get_softc(dev);
+
+	pdev->dev.bd->props.brightness = pdev->dev.bd->props.max_brightness *
+		props->brightness / 100;
+	return (pdev->dev.bd->ops->update_status(pdev->dev.bd));
+}
+
+struct backlight_device *
+linux_backlight_device_register(const char *name, struct device *dev,
+    void *data, const struct backlight_ops *ops, struct backlight_properties *props)
+{
+
+	dev->bd = malloc(sizeof(*dev->bd), M_DEVBUF, M_WAITOK | M_ZERO);
+	dev->bd->ops = ops;
+	dev->bd->props.type = props->type;
+	dev->bd->props.max_brightness = props->max_brightness;
+	dev->bd->props.brightness = props->brightness;
+	dev->bd->props.power = props->power;
+	dev->bd->data = data;
+	dev->bd->dev = dev;
+	dev->bd->name = strdup(name, M_DEVBUF);
+
+	dev->backlight_dev = backlight_register(name, dev->bsddev);
+
+	return (dev->bd);
+}
+
+void
+linux_backlight_device_unregister(struct backlight_device *bd)
+{
+
+	backlight_destroy(bd->dev->backlight_dev);
+	free(bd->name, M_DEVBUF);
+	free(bd, M_DEVBUF);
+}

sys/conf/kmod.mk

@@ -91,6 +91,7 @@ CFLAGS+=	-fno-strict-aliasing
 WERROR?=	-Werror
 
 LINUXKPI_GENSRCS+= \
+	backlight_if.h \
 	bus_if.h \
 	device_if.h \
 	pci_if.h \