[PATCH] Driver for Apple Cinema Display

This is a driver to control the brightness of an Apple Cinema Display over
USB.  It updates the local brightness value if the user presses a button on
the display.
Signed-off-by: Michael Hanselmann <linux-kernel@hansmi.ch>
Cc: Oliver Neukum <oliver@neukum.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

drivers/usb/Makefile

@@ -61,6 +61,7 @@ obj-$(CONFIG_USB_TEST)		+= misc/
 obj-$(CONFIG_USB_USS720)	+= misc/
 obj-$(CONFIG_USB_PHIDGETSERVO)	+= misc/
 obj-$(CONFIG_USB_SISUSBVGA)	+= misc/
+obj-$(CONFIG_USB_APPLEDISPLAY)	+= misc/
 
 obj-$(CONFIG_USB_ATM)		+= atm/
 obj-$(CONFIG_USB_SPEEDTOUCH)	+= atm/

drivers/usb/misc/Kconfig

@@ -137,6 +137,15 @@ config USB_IDMOUSE
 
 	  See also <http://www.fs.tum.de/~echtler/idmouse/>.
 
+config USB_APPLEDISPLAY
+	tristate "Apple Cinema Display support"
+	depends on USB
+	select BACKLIGHT_LCD_SUPPORT
+	select BACKLIGHT_CLASS_DEVICE
+	help
+	  Say Y here if you want to control the backlight of Apple Cinema
+	  Displays over USB. This driver provides a sysfs interface.
+
 source "drivers/usb/misc/sisusbvga/Kconfig"
 
 config USB_LD

drivers/usb/misc/Makefile

@@ -17,6 +17,7 @@ obj-$(CONFIG_USB_PHIDGETSERVO)	+= phidgetservo.o
 obj-$(CONFIG_USB_RIO500)	+= rio500.o
 obj-$(CONFIG_USB_TEST)		+= usbtest.o
 obj-$(CONFIG_USB_USS720)	+= uss720.o
+obj-$(CONFIG_USB_APPLEDISPLAY)	+= appledisplay.o
 
 obj-$(CONFIG_USB_SISUSBVGA)	+= sisusbvga/
 

drivers/usb/misc/appledisplay.c

+/*
+ * Apple Cinema Display driver
+ *
+ * Copyright (C) 2006  Michael Hanselmann (linux-kernel@hansmi.ch)
+ *
+ * Thanks to Caskey L. Dickson for his work with acdctl.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ */
+
+#include <linux/config.h>
+#include <linux/kernel.h>
+#include <linux/errno.h>
+#include <linux/init.h>
+#include <linux/module.h>
+#include <linux/usb.h>
+#include <linux/backlight.h>
+#include <linux/timer.h>
+#include <linux/workqueue.h>
+#include <asm/atomic.h>
+#include <asm/semaphore.h>
+
+#define APPLE_VENDOR_ID		0x05AC
+
+#define USB_REQ_GET_REPORT	0x01
+#define USB_REQ_SET_REPORT	0x09
+
+#define ACD_USB_TIMEOUT		250
+
+#define ACD_USB_EDID		0x0302
+#define ACD_USB_BRIGHTNESS	0x0310
+
+#define ACD_BTN_NONE		0
+#define ACD_BTN_BRIGHT_UP	3
+#define ACD_BTN_BRIGHT_DOWN	4
+
+#define ACD_URB_BUFFER_LEN	2
+#define ACD_MSG_BUFFER_LEN	2
+
+#define APPLEDISPLAY_DEVICE(prod)				\
+	.match_flags = USB_DEVICE_ID_MATCH_DEVICE |		\
+		       USB_DEVICE_ID_MATCH_INT_CLASS |		\
+		       USB_DEVICE_ID_MATCH_INT_PROTOCOL,	\
+	.idVendor = APPLE_VENDOR_ID,				\
+	.idProduct = (prod),					\
+	.bInterfaceClass = USB_CLASS_HID,			\
+	.bInterfaceProtocol = 0x00
+
+/* table of devices that work with this driver */
+static struct usb_device_id appledisplay_table [] = {
+	{ APPLEDISPLAY_DEVICE(0x9218) },
+	{ APPLEDISPLAY_DEVICE(0x9219) },
+	{ APPLEDISPLAY_DEVICE(0x921d) },
+
+	/* Terminating entry */
+	{ }
+};
+MODULE_DEVICE_TABLE(usb, appledisplay_table);
+
+/* Structure to hold all of our device specific stuff */
+struct appledisplay {
+	struct usb_device *udev;	/* usb device */
+	struct urb *urb;		/* usb request block */
+	struct backlight_device *bd;	/* backlight device */
+	char *urbdata;			/* interrupt URB data buffer */
+	char *msgdata;			/* control message data buffer */
+
+	struct work_struct work;
+	int button_pressed;
+	spinlock_t lock;
+};
+
+static atomic_t count_displays = ATOMIC_INIT(0);
+static struct workqueue_struct *wq;
+
+static void appledisplay_complete(struct urb *urb, struct pt_regs *regs)
+{
+	struct appledisplay *pdata = urb->context;
+	unsigned long flags;
+	int retval;
+
+	switch (urb->status) {
+	case 0:
+		/* success */
+		break;
+	case -EOVERFLOW:
+		printk(KERN_ERR "appletouch: OVERFLOW with data "
+			"length %d, actual length is %d\n",
+			ACD_URB_BUFFER_LEN, pdata->urb->actual_length);
+	case -ECONNRESET:
+	case -ENOENT:
+	case -ESHUTDOWN:
+		/* This urb is terminated, clean up */
+		dbg("%s - urb shutting down with status: %d",
+			__FUNCTION__, urb->status);
+		return;
+	default:
+		dbg("%s - nonzero urb status received: %d",
+			__FUNCTION__, urb->status);
+		goto exit;
+	}
+
+	spin_lock_irqsave(&pdata->lock, flags);
+
+	switch(pdata->urbdata[1]) {
+	case ACD_BTN_BRIGHT_UP:
+	case ACD_BTN_BRIGHT_DOWN:
+		pdata->button_pressed = 1;
+		queue_work(wq, &pdata->work);
+		break;
+	case ACD_BTN_NONE:
+	default:
+		pdata->button_pressed = 0;
+		break;
+	}
+
+	spin_unlock_irqrestore(&pdata->lock, flags);
+
+exit:
+	retval = usb_submit_urb(pdata->urb, GFP_ATOMIC);
+	if (retval) {
+		err("%s - usb_submit_urb failed with result %d",
+			__FUNCTION__, retval);
+	}
+}
+
+static int appledisplay_bl_update_status(struct backlight_device *bd)
+{
+	struct appledisplay *pdata = class_get_devdata(&bd->class_dev);
+	int retval;
+
+	pdata->msgdata[0] = 0x10;
+	pdata->msgdata[1] = bd->props->brightness;
+
+	retval = usb_control_msg(
+		pdata->udev,
+		usb_sndctrlpipe(pdata->udev, 0),
+		USB_REQ_SET_REPORT,
+		USB_DIR_OUT | USB_TYPE_CLASS | USB_RECIP_INTERFACE,
+		ACD_USB_BRIGHTNESS,
+		0,
+		pdata->msgdata, 2,
+		ACD_USB_TIMEOUT);
+
+	return retval;
+}
+
+static int appledisplay_bl_get_brightness(struct backlight_device *bd)
+{
+	struct appledisplay *pdata = class_get_devdata(&bd->class_dev);
+	int retval;
+
+	retval = usb_control_msg(
+		pdata->udev,
+		usb_rcvctrlpipe(pdata->udev, 0),
+		USB_REQ_GET_REPORT,
+		USB_DIR_IN | USB_TYPE_CLASS | USB_RECIP_INTERFACE,
+		ACD_USB_BRIGHTNESS,
+		0,
+		pdata->msgdata, 2,
+		ACD_USB_TIMEOUT);
+
+	if (retval < 0)
+		return retval;
+	else
+		return pdata->msgdata[1];
+}
+
+static struct backlight_properties appledisplay_bl_data = {
+	.owner		= THIS_MODULE,
+	.get_brightness	= appledisplay_bl_get_brightness,
+	.update_status	= appledisplay_bl_update_status,
+	.max_brightness	= 0xFF
+};
+
+static void appledisplay_work(void *private)
+{
+	struct appledisplay *pdata = private;
+	int retval;
+
+	up(&pdata->bd->sem);
+	retval = appledisplay_bl_get_brightness(pdata->bd);
+	if (retval >= 0)
+		pdata->bd->props->brightness = retval;
+	down(&pdata->bd->sem);
+
+	/* Poll again in about 125ms if there's still a button pressed */
+	if (pdata->button_pressed)
+		schedule_delayed_work(&pdata->work, HZ / 8);
+}
+
+static int appledisplay_probe(struct usb_interface *iface,
+	const struct usb_device_id *id)
+{
+	struct appledisplay *pdata;
+	struct usb_device *udev = interface_to_usbdev(iface);
+	struct usb_host_interface *iface_desc;
+	struct usb_endpoint_descriptor *endpoint;
+	int int_in_endpointAddr = 0;
+	int i, retval = -ENOMEM, brightness;
+	char bl_name[20];
+
+	/* set up the endpoint information */
+	/* use only the first interrupt-in endpoint */
+	iface_desc = iface->cur_altsetting;
+	for (i = 0; i < iface_desc->desc.bNumEndpoints; i++) {
+		endpoint = &iface_desc->endpoint[i].desc;
+		if (!int_in_endpointAddr &&
+		    (endpoint->bEndpointAddress & USB_DIR_IN) &&
+		    ((endpoint->bmAttributes & USB_ENDPOINT_XFERTYPE_MASK) ==
+		     USB_ENDPOINT_XFER_INT)) {
+			/* we found an interrupt in endpoint */
+			int_in_endpointAddr = endpoint->bEndpointAddress;
+			break;
+		}
+	}
+	if (!int_in_endpointAddr) {
+		err("Could not find int-in endpoint");
+		return -EIO;
+	}
+
+	/* allocate memory for our device state and initialize it */
+	pdata = kzalloc(sizeof(struct appledisplay), GFP_KERNEL);
+	if (!pdata) {
+		retval = -ENOMEM;
+		err("Out of memory");
+		goto error;
+	}
+
+	pdata->udev = udev;
+
+	spin_lock_init(&pdata->lock);
+	INIT_WORK(&pdata->work, appledisplay_work, pdata);
+
+	/* Allocate buffer for control messages */
+	pdata->msgdata = kmalloc(ACD_MSG_BUFFER_LEN, GFP_KERNEL);
+	if (!pdata->msgdata) {
+		retval = -ENOMEM;
+		err("appledisplay: Allocating buffer for control messages "
+			"failed");
+		goto error;
+	}
+
+	/* Allocate interrupt URB */
+	pdata->urb = usb_alloc_urb(0, GFP_KERNEL);
+	if (!pdata->urb) {
+		retval = -ENOMEM;
+		err("appledisplay: Allocating URB failed");
+		goto error;
+	}
+
+	/* Allocate buffer for interrupt data */
+	pdata->urbdata = usb_buffer_alloc(pdata->udev, ACD_URB_BUFFER_LEN,
+		GFP_KERNEL, &pdata->urb->transfer_dma);
+	if (!pdata->urbdata) {
+		retval = -ENOMEM;
+		err("appledisplay: Allocating URB buffer failed");
+		goto error;
+	}
+
+	/* Configure interrupt URB */
+	usb_fill_int_urb(pdata->urb, udev,
+		usb_rcvintpipe(udev, int_in_endpointAddr),
+		pdata->urbdata, ACD_URB_BUFFER_LEN, appledisplay_complete,
+		pdata, 1);
+	if (usb_submit_urb(pdata->urb, GFP_KERNEL)) {
+		retval = -EIO;
+		err("appledisplay: Submitting URB failed");
+		goto error;
+	}
+
+	/* Register backlight device */
+	snprintf(bl_name, sizeof(bl_name), "appledisplay%d",
+		atomic_inc_return(&count_displays) - 1);
+	pdata->bd = backlight_device_register(bl_name, pdata,
+						&appledisplay_bl_data);
+	if (IS_ERR(pdata->bd)) {
+		err("appledisplay: Backlight registration failed");
+		goto error;
+	}
+
+	/* Try to get brightness */
+	up(&pdata->bd->sem);
+	brightness = appledisplay_bl_get_brightness(pdata->bd);
+	down(&pdata->bd->sem);
+
+	if (brightness < 0) {
+		retval = brightness;
+		err("appledisplay: Error while getting initial brightness: %d", retval);
+		goto error;
+	}
+
+	/* Set brightness in backlight device */
+	up(&pdata->bd->sem);
+	pdata->bd->props->brightness = brightness;
+	down(&pdata->bd->sem);
+
+	/* save our data pointer in the interface device */
+	usb_set_intfdata(iface, pdata);
+
+	printk(KERN_INFO "appledisplay: Apple Cinema Display connected\n");
+
+	return 0;
+
+error:
+	if (pdata) {
+		if (pdata->urb) {
+			usb_kill_urb(pdata->urb);
+			if (pdata->urbdata)
+				usb_buffer_free(pdata->udev, ACD_URB_BUFFER_LEN,
+					pdata->urbdata, pdata->urb->transfer_dma);
+			usb_free_urb(pdata->urb);
+		}
+		if (pdata->bd)
+			backlight_device_unregister(pdata->bd);
+		kfree(pdata->msgdata);
+	}
+	usb_set_intfdata(iface, NULL);
+	kfree(pdata);
+	return retval;
+}
+
+static void appledisplay_disconnect(struct usb_interface *iface)
+{
+	struct appledisplay *pdata = usb_get_intfdata(iface);
+
+	if (pdata) {
+		usb_kill_urb(pdata->urb);
+		cancel_delayed_work(&pdata->work);
+		backlight_device_unregister(pdata->bd);
+		usb_buffer_free(pdata->udev, ACD_URB_BUFFER_LEN,
+			pdata->urbdata, pdata->urb->transfer_dma);
+		usb_free_urb(pdata->urb);
+		kfree(pdata->msgdata);
+		kfree(pdata);
+	}
+
+	printk(KERN_INFO "appledisplay: Apple Cinema Display disconnected\n");
+}
+
+static struct usb_driver appledisplay_driver = {
+	.name		= "appledisplay",
+	.probe		= appledisplay_probe,
+	.disconnect	= appledisplay_disconnect,
+	.id_table	= appledisplay_table,
+};
+
+static int __init appledisplay_init(void)
+{
+	wq = create_singlethread_workqueue("appledisplay");
+	if (!wq) {
+		err("Could not create work queue\n");
+		return -ENOMEM;
+	}
+
+	return usb_register(&appledisplay_driver);
+}
+
+static void __exit appledisplay_exit(void)
+{
+	flush_workqueue(wq);
+	destroy_workqueue(wq);
+	usb_deregister(&appledisplay_driver);
+}
+
+MODULE_AUTHOR("Michael Hanselmann");
+MODULE_DESCRIPTION("Apple Cinema Display driver");
+MODULE_LICENSE("GPL");
+
+module_init(appledisplay_init);
+module_exit(appledisplay_exit);