[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>

3 files changed, 393 insertions, 0 deletions

diff --git a/drivers/usb/misc/Kconfig b/drivers/usb/misc/Kconfig
index 8ba6a701e9c1..af79d0447bbd 100644
--- a/drivers/usb/misc/Kconfig
+++ b/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
diff --git a/drivers/usb/misc/Makefile b/drivers/usb/misc/Makefile
index 6c693bc68e2e..946537d31d91 100644
--- a/drivers/usb/misc/Makefile
+++ b/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/
 
diff --git a/drivers/usb/misc/appledisplay.c b/drivers/usb/misc/appledisplay.c
new file mode 100644
index 000000000000..bfde82f5d180
--- /dev/null
+++ b/drivers/usb/misc/appledisplay.c
@@ -0,0 +1,383 @@
+/*
+ * 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);