nouveau: Add in-kernel backlight control support

Several nvidia-based systems don't support backlight control via the
standard ACPI control mechanisms. Instead, it's necessary for the driver
to modify the backlight control registers directly. This patch adds
support for determining whether the registers appear to be in use, and
if so registers a kernel backlight device to control them. The backlight
can then be controlled via existing userspace tools.

Signed-off-by: Matthew Garrett <mjg@redhat.com>
Signed-off-by: Ben Skeggs <bskeggs@redhat.com>

2 files changed, 157 insertions, 0 deletions

diff --git a/linux-core/Makefile.kernel b/linux-core/Makefile.kernel
index 1e03347e..0bea35dd 100644
--- a/linux-core/Makefile.kernel
+++ b/linux-core/Makefile.kernel
@@ -22,6 +22,7 @@ i810-objs   := i810_drv.o i810_dma.o
 nouveau-objs := nouveau_drv.o nouveau_state.o nouveau_fifo.o nouveau_mem.o \
 		nouveau_object.o nouveau_irq.o nouveau_notifier.o nouveau_swmthd.o \
 		nouveau_sgdma.o nouveau_dma.o nouveau_bo.o nouveau_fence.o \
+		nouveau_backlight.o \
 		nv04_timer.o \
 		nv04_mc.o nv40_mc.o nv50_mc.o \
 		nv04_fb.o nv10_fb.o nv40_fb.o \
diff --git a/linux-core/nouveau_backlight.c b/linux-core/nouveau_backlight.c
new file mode 100644
index 00000000..dc75c443
--- /dev/null
+++ b/linux-core/nouveau_backlight.c
@@ -0,0 +1,156 @@
+/*
+ * Copyright (C) 2009 Red Hat <mjg@redhat.com>
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining
+ * a copy of this software and associated documentation files (the
+ * "Software"), to deal in the Software without restriction, including
+ * without limitation the rights to use, copy, modify, merge, publish,
+ * distribute, sublicense, and/or sell copies of the Software, and to
+ * permit persons to whom the Software is furnished to do so, subject to
+ * the following conditions:
+ *
+ * The above copyright notice and this permission notice (including the
+ * next paragraph) shall be included in all copies or substantial
+ * portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+ * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+ * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
+ * IN NO EVENT SHALL THE COPYRIGHT OWNER(S) AND/OR ITS SUPPLIERS BE
+ * LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
+ * OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
+ * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+ *
+ */
+
+/*
+ * Authors:
+ *  Matthew Garrett <mjg@redhat.com>
+ *
+ * Register locations derived from NVClock by Roderick Colenbrander
+ */
+
+#include <linux/backlight.h>
+
+#include "drmP.h"
+#include "nouveau_drv.h"
+#include "nouveau_drm.h"
+#include "nouveau_reg.h"
+
+static int nv40_get_intensity(struct backlight_device *bd)
+{
+	struct drm_device *dev = bl_get_data(bd);
+	struct drm_nouveau_private *dev_priv = dev->dev_private;
+	int val = (NV_READ(NV40_PMC_BACKLIGHT) & NV40_PMC_BACKLIGHT_MASK) >> 16;
+
+	return val;
+}
+
+static int nv40_set_intensity(struct backlight_device *bd)
+{
+	struct drm_device *dev = bl_get_data(bd);
+	struct drm_nouveau_private *dev_priv = dev->dev_private;
+	int val = bd->props.brightness;
+	int reg = NV_READ(NV40_PMC_BACKLIGHT);
+
+	NV_WRITE(NV40_PMC_BACKLIGHT,
+		 (val << 16) | (reg & ~NV40_PMC_BACKLIGHT_MASK));
+
+	return 0;
+}
+
+static struct backlight_ops nv40_bl_ops = {
+	.options = BL_CORE_SUSPENDRESUME,
+	.get_brightness = nv40_get_intensity,
+	.update_status = nv40_set_intensity,
+};
+
+static int nv50_get_intensity(struct backlight_device *bd)
+{
+	struct drm_device *dev = bl_get_data(bd);
+	struct drm_nouveau_private *dev_priv = dev->dev_private;
+
+	return NV_READ(NV50_PDISPLAY_BACKLIGHT);
+}
+
+static int nv50_set_intensity(struct backlight_device *bd)
+{
+	struct drm_device *dev = bl_get_data(bd);
+	struct drm_nouveau_private *dev_priv = dev->dev_private;
+	int val = bd->props.brightness;
+
+	NV_WRITE(NV50_PDISPLAY_BACKLIGHT, val | NV50_PDISPLAY_BACKLIGHT_ENABLE);
+
+	return 0;
+}
+
+static struct backlight_ops nv50_bl_ops = {
+	.options = BL_CORE_SUSPENDRESUME,
+	.get_brightness = nv50_get_intensity,
+	.update_status = nv50_set_intensity,
+};
+
+static int nouveau_nv40_backlight_init(struct drm_device *dev)
+{
+	struct drm_nouveau_private *dev_priv = dev->dev_private;
+	struct backlight_device *bd;
+	
+	if (!(NV_READ(NV40_PMC_BACKLIGHT) & NV40_PMC_BACKLIGHT_MASK))
+		return 0;
+
+	bd = backlight_device_register("nv_backlight", &dev->pdev->dev, dev,
+				       &nv40_bl_ops);
+	if (IS_ERR(bd))
+		return PTR_ERR(bd);
+
+	dev_priv->backlight = bd;
+	bd->props.max_brightness = 31;
+	bd->props.brightness = nv40_get_intensity(bd);
+	backlight_update_status(bd);
+
+	return 0;
+}
+
+static int nouveau_nv50_backlight_init(struct drm_device *dev)
+{
+	struct drm_nouveau_private *dev_priv = dev->dev_private;
+	struct backlight_device *bd;
+
+	if (!NV_READ(NV50_PDISPLAY_BACKLIGHT))
+		return 0;
+
+	bd = backlight_device_register("nv_backlight", &dev->pdev->dev, dev,
+				       &nv50_bl_ops);
+	if (IS_ERR(bd))
+		return PTR_ERR(bd);
+
+	dev_priv->backlight = bd;
+	bd->props.max_brightness = 1025;
+	bd->props.brightness = nv50_get_intensity(bd);
+	backlight_update_status(bd);
+	return 0;
+}
+
+int nouveau_backlight_init(struct drm_device *dev)
+{
+	struct drm_nouveau_private *dev_priv = dev->dev_private;
+
+	switch (dev_priv->card_type) {
+	case NV_40:
+	case NV_44:
+		return nouveau_nv40_backlight_init(dev);
+		break;
+	case NV_50:
+		return nouveau_nv50_backlight_init(dev);
+		break;
+	}
+	return 0;
+}
+
+void nouveau_backlight_exit(struct drm_device *dev)
+{
+	struct drm_nouveau_private *dev_priv = dev->dev_private;
+
+	if (dev_priv->backlight)
+		backlight_device_unregister(dev_priv->backlight);
+}