platform/x86: Add driver for Apple gmux device
authorSeth Forshee <seth.forshee@canonical.com>
Fri, 16 Mar 2012 19:41:22 +0000 (14:41 -0500)
committerMatthew Garrett <mjg@redhat.com>
Mon, 26 Mar 2012 19:05:25 +0000 (15:05 -0400)
Apple laptops with hybrid graphics have a device named gmux that
controls the muxing of the LVDS panel between the GPUs as well as screen
brightness. This driver adds support for the gmux device. Only backlight
control is supported initially.

Signed-off-by: Seth Forshee <seth.forshee@canonical.com>
Signed-off-by: Matthew Garrett <mjg@redhat.com>
Tested-by: Grant Likely <grant.likely@secretlab.ca>
drivers/platform/x86/Kconfig
drivers/platform/x86/Makefile
drivers/platform/x86/apple-gmux.c [new file with mode: 0644]

index ce10f0313961a5643e6364f2f656e5d6d76c4f64..c5b4bfed7bb4e57035bd47ebd9bbf9a747f451d4 100644 (file)
@@ -752,4 +752,14 @@ config SAMSUNG_Q10
          This driver provides support for backlight control on Samsung Q10
          and related laptops, including Dell Latitude X200.
 
+config APPLE_GMUX
+       tristate "Apple Gmux Driver"
+       depends on PNP
+       select BACKLIGHT_CLASS_DEVICE
+       ---help---
+         This driver provides support for the gmux device found on many
+         Apple laptops, which controls the display mux for the hybrid
+         graphics as well as the backlight. Currently only backlight
+         control is supported by the driver.
+
 endif # X86_PLATFORM_DEVICES
index dcfee6b2606dce32cb65b1b98663ca61cf4a4e5b..bf7e4f935b1755ca9562af71c697ac1303d1d8f8 100644 (file)
@@ -49,3 +49,4 @@ obj-$(CONFIG_MXM_WMI)         += mxm-wmi.o
 obj-$(CONFIG_INTEL_MID_POWER_BUTTON)   += intel_mid_powerbtn.o
 obj-$(CONFIG_INTEL_OAKTRAIL)   += intel_oaktrail.o
 obj-$(CONFIG_SAMSUNG_Q10)      += samsung-q10.o
+obj-$(CONFIG_APPLE_GMUX)       += apple-gmux.o
diff --git a/drivers/platform/x86/apple-gmux.c b/drivers/platform/x86/apple-gmux.c
new file mode 100644 (file)
index 0000000..8a582bd
--- /dev/null
@@ -0,0 +1,244 @@
+/*
+ *  Gmux driver for Apple laptops
+ *
+ *  Copyright (C) Canonical Ltd. <seth.forshee@canonical.com>
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License version 2 as
+ *  published by the Free Software Foundation.
+ */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/module.h>
+#include <linux/kernel.h>
+#include <linux/init.h>
+#include <linux/backlight.h>
+#include <linux/acpi.h>
+#include <linux/pnp.h>
+#include <linux/apple_bl.h>
+#include <linux/slab.h>
+#include <acpi/video.h>
+#include <asm/io.h>
+
+struct apple_gmux_data {
+       unsigned long iostart;
+       unsigned long iolen;
+
+       struct backlight_device *bdev;
+};
+
+/*
+ * gmux port offsets. Many of these are not yet used, but may be in the
+ * future, and it's useful to have them documented here anyhow.
+ */
+#define GMUX_PORT_VERSION_MAJOR                0x04
+#define GMUX_PORT_VERSION_MINOR                0x05
+#define GMUX_PORT_VERSION_RELEASE      0x06
+#define GMUX_PORT_SWITCH_DISPLAY       0x10
+#define GMUX_PORT_SWITCH_GET_DISPLAY   0x11
+#define GMUX_PORT_INTERRUPT_ENABLE     0x14
+#define GMUX_PORT_INTERRUPT_STATUS     0x16
+#define GMUX_PORT_SWITCH_DDC           0x28
+#define GMUX_PORT_SWITCH_EXTERNAL      0x40
+#define GMUX_PORT_SWITCH_GET_EXTERNAL  0x41
+#define GMUX_PORT_DISCRETE_POWER       0x50
+#define GMUX_PORT_MAX_BRIGHTNESS       0x70
+#define GMUX_PORT_BRIGHTNESS           0x74
+
+#define GMUX_MIN_IO_LEN                        (GMUX_PORT_BRIGHTNESS + 4)
+
+#define GMUX_INTERRUPT_ENABLE          0xff
+#define GMUX_INTERRUPT_DISABLE         0x00
+
+#define GMUX_INTERRUPT_STATUS_ACTIVE   0
+#define GMUX_INTERRUPT_STATUS_DISPLAY  (1 << 0)
+#define GMUX_INTERRUPT_STATUS_POWER    (1 << 2)
+#define GMUX_INTERRUPT_STATUS_HOTPLUG  (1 << 3)
+
+#define GMUX_BRIGHTNESS_MASK           0x00ffffff
+#define GMUX_MAX_BRIGHTNESS            GMUX_BRIGHTNESS_MASK
+
+static inline u8 gmux_read8(struct apple_gmux_data *gmux_data, int port)
+{
+       return inb(gmux_data->iostart + port);
+}
+
+static inline void gmux_write8(struct apple_gmux_data *gmux_data, int port,
+                              u8 val)
+{
+       outb(val, gmux_data->iostart + port);
+}
+
+static inline u32 gmux_read32(struct apple_gmux_data *gmux_data, int port)
+{
+       return inl(gmux_data->iostart + port);
+}
+
+static int gmux_get_brightness(struct backlight_device *bd)
+{
+       struct apple_gmux_data *gmux_data = bl_get_data(bd);
+       return gmux_read32(gmux_data, GMUX_PORT_BRIGHTNESS) &
+              GMUX_BRIGHTNESS_MASK;
+}
+
+static int gmux_update_status(struct backlight_device *bd)
+{
+       struct apple_gmux_data *gmux_data = bl_get_data(bd);
+       u32 brightness = bd->props.brightness;
+
+       /*
+        * Older gmux versions require writing out lower bytes first then
+        * setting the upper byte to 0 to flush the values. Newer versions
+        * accept a single u32 write, but the old method also works, so we
+        * just use the old method for all gmux versions.
+        */
+       gmux_write8(gmux_data, GMUX_PORT_BRIGHTNESS, brightness);
+       gmux_write8(gmux_data, GMUX_PORT_BRIGHTNESS + 1, brightness >> 8);
+       gmux_write8(gmux_data, GMUX_PORT_BRIGHTNESS + 2, brightness >> 16);
+       gmux_write8(gmux_data, GMUX_PORT_BRIGHTNESS + 3, 0);
+
+       return 0;
+}
+
+static const struct backlight_ops gmux_bl_ops = {
+       .get_brightness = gmux_get_brightness,
+       .update_status = gmux_update_status,
+};
+
+static int __devinit gmux_probe(struct pnp_dev *pnp,
+                               const struct pnp_device_id *id)
+{
+       struct apple_gmux_data *gmux_data;
+       struct resource *res;
+       struct backlight_properties props;
+       struct backlight_device *bdev;
+       u8 ver_major, ver_minor, ver_release;
+       int ret = -ENXIO;
+
+       gmux_data = kzalloc(sizeof(*gmux_data), GFP_KERNEL);
+       if (!gmux_data)
+               return -ENOMEM;
+       pnp_set_drvdata(pnp, gmux_data);
+
+       res = pnp_get_resource(pnp, IORESOURCE_IO, 0);
+       if (!res) {
+               pr_err("Failed to find gmux I/O resource\n");
+               goto err_free;
+       }
+
+       gmux_data->iostart = res->start;
+       gmux_data->iolen = res->end - res->start;
+
+       if (gmux_data->iolen < GMUX_MIN_IO_LEN) {
+               pr_err("gmux I/O region too small (%lu < %u)\n",
+                      gmux_data->iolen, GMUX_MIN_IO_LEN);
+               goto err_free;
+       }
+
+       if (!request_region(gmux_data->iostart, gmux_data->iolen,
+                           "Apple gmux")) {
+               pr_err("gmux I/O already in use\n");
+               goto err_free;
+       }
+
+       /*
+        * On some machines the gmux is in ACPI even thought the machine
+        * doesn't really have a gmux. Check for invalid version information
+        * to detect this.
+        */
+       ver_major = gmux_read8(gmux_data, GMUX_PORT_VERSION_MAJOR);
+       ver_minor = gmux_read8(gmux_data, GMUX_PORT_VERSION_MINOR);
+       ver_release = gmux_read8(gmux_data, GMUX_PORT_VERSION_RELEASE);
+       if (ver_major == 0xff && ver_minor == 0xff && ver_release == 0xff) {
+               pr_info("gmux device not present\n");
+               ret = -ENODEV;
+               goto err_release;
+       }
+
+       pr_info("Found gmux version %d.%d.%d\n", ver_major, ver_minor,
+               ver_release);
+
+       memset(&props, 0, sizeof(props));
+       props.type = BACKLIGHT_PLATFORM;
+       props.max_brightness = gmux_read32(gmux_data, GMUX_PORT_MAX_BRIGHTNESS);
+
+       /*
+        * Currently it's assumed that the maximum brightness is less than
+        * 2^24 for compatibility with old gmux versions. Cap the max
+        * brightness at this value, but print a warning if the hardware
+        * reports something higher so that it can be fixed.
+        */
+       if (WARN_ON(props.max_brightness > GMUX_MAX_BRIGHTNESS))
+               props.max_brightness = GMUX_MAX_BRIGHTNESS;
+
+       bdev = backlight_device_register("gmux_backlight", &pnp->dev,
+                                        gmux_data, &gmux_bl_ops, &props);
+       if (IS_ERR(bdev)) {
+               ret = PTR_ERR(bdev);
+               goto err_release;
+       }
+
+       gmux_data->bdev = bdev;
+       bdev->props.brightness = gmux_get_brightness(bdev);
+       backlight_update_status(bdev);
+
+       /*
+        * The backlight situation on Macs is complicated. If the gmux is
+        * present it's the best choice, because it always works for
+        * backlight control and supports more levels than other options.
+        * Disable the other backlight choices.
+        */
+       acpi_video_unregister();
+       apple_bl_unregister();
+
+       return 0;
+
+err_release:
+       release_region(gmux_data->iostart, gmux_data->iolen);
+err_free:
+       kfree(gmux_data);
+       return ret;
+}
+
+static void __devexit gmux_remove(struct pnp_dev *pnp)
+{
+       struct apple_gmux_data *gmux_data = pnp_get_drvdata(pnp);
+
+       backlight_device_unregister(gmux_data->bdev);
+       release_region(gmux_data->iostart, gmux_data->iolen);
+       kfree(gmux_data);
+
+       acpi_video_register();
+       apple_bl_register();
+}
+
+static const struct pnp_device_id gmux_device_ids[] = {
+       {"APP000B", 0},
+       {"", 0}
+};
+
+static struct pnp_driver gmux_pnp_driver = {
+       .name           = "apple-gmux",
+       .probe          = gmux_probe,
+       .remove         = __devexit_p(gmux_remove),
+       .id_table       = gmux_device_ids,
+};
+
+static int __init apple_gmux_init(void)
+{
+       return pnp_register_driver(&gmux_pnp_driver);
+}
+
+static void __exit apple_gmux_exit(void)
+{
+       pnp_unregister_driver(&gmux_pnp_driver);
+}
+
+module_init(apple_gmux_init);
+module_exit(apple_gmux_exit);
+
+MODULE_AUTHOR("Seth Forshee <seth.forshee@canonical.com>");
+MODULE_DESCRIPTION("Apple Gmux Driver");
+MODULE_LICENSE("GPL");
+MODULE_DEVICE_TABLE(pnp, gmux_device_ids);