Add intel_backlight

A trivial tool to adjust the backlight registers (gen5+ only atm).

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>

tools/Makefile.am

@@ -1,6 +1,7 @@
 bin_PROGRAMS = \
 	intel_disable_clock_gating \
 	intel_audio_dump \
+	intel_backlight \
 	intel_bios_dumper \
 	intel_bios_reader \
 	intel_error_decode \

tools/intel_backlight.c

@@ -0,0 +1,69 @@
+/*
+ * Copyright © 2011 Intel Corporation
+ *
+ * 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 AUTHORS OR COPYRIGHT HOLDERS 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:
+ *	Chris Wilson <chris@chris-wilson.co.uk>
+ *
+ */
+
+#include <stdint.h>
+#include <stdlib.h>
+#include <stdio.h>
+#include <string.h>
+
+#include "intel_gpu_tools.h"
+
+/* XXX PCH only today */
+
+static uint32_t reg_read(uint32_t reg)
+{
+	return *(volatile uint32_t *)((volatile char*)mmio + reg);
+}
+
+static void reg_write(uint32_t reg, uint32_t val)
+{
+	*(volatile uint32_t *)((volatile char*)mmio + reg) = val;
+}
+
+int main(int argc, char** argv)
+{
+	uint32_t current, max;
+
+	intel_get_mmio(intel_get_pci_device());
+
+	current = reg_read(BLC_PWM_CPU_CTL) & BACKLIGHT_DUTY_CYCLE_MASK;
+	max = reg_read(BLC_PWM_PCH_CTL2) >> 16;
+
+	printf ("current backlight value: %d%%\n", current * 100 / max);
+
+	if (argc > 1) {
+		uint32_t v = atoi (argv[1]) * max / 100;
+		if (v > max)
+			v = max;
+		reg_write(BLC_PWM_CPU_CTL,
+			  (reg_read(BLC_PWM_CPU_CTL) &~ BACKLIGHT_DUTY_CYCLE_MASK) | v);
+		(void) reg_read(BLC_PWM_CPU_CTL);
+		printf ("set backlight to %d%%\n", v * 100 / max);
+	}
+
+	return 0;
+}