vga_switcheroo: initial implementation (v15)

Many new laptops now come with 2 gpus, one to be used for low power
modes and one for gaming/on-ac applications. These GPUs are typically
wired to the laptop panel and VGA ports via a multiplexer unit which
is controlled via ACPI methods.

4 combinations of systems typically exist - with 2 ACPI methods.
Intel/ATI - Lenovo W500/T500 - use ATPX ACPI method
ATI/ATI - some ASUS - use ATPX ACPI Method
Intel/Nvidia - - use _DSM ACPI method
Nvidia/Nvidia -  - use _DSM ACPI method.

TODO:
This patch adds support for the ATPX method and initial bits
for the _DSM methods that need to written by someone with
access to the hardware.
Add a proper non-debugfs interface - need to get some proper
testing first.

v2: add power up/down support for both devices
on W500 puts i915/radeon into D3 and cuts power to radeon.

v3: redo probing methods, no DMI list, drm devices call to
register with switcheroo, it tries to find an ATPX method on
any device and once there is two devices + ATPX it inits the
switcher.

v4: ATPX msg handling using buffers - should work on more machines

v5: rearchitect after more mjg59 discussion - move ATPX handling to
    radeon driver.

v6: add file headers + initial nouveau bits (to be filled out).

v7: merge delayed switcher code.

v8: avoid suspend/resume of gpu that is off

v9: rearchitect - mjg59 is always right. - move all ATPX code to
radeon, should allow simpler DSM also proper ATRM handling

v10: add ATRM support for radeon BIOS, add mutex to lock vgasr_priv

v11: fix bug in resuming Intel for 2nd time.

v12: start fixing up nvidia code blindly.

v13: blindly guess at finishing nvidia code

v14: remove radeon audio hacks - fix up intel resume more like upstream

v15: clean up printks + remove unnecessary igd/dis pointers

mount debugfs

/sys/kernel/debug/vgaswitcheroo/switch - should exist if ATPX detected
 + 2 cards.

DIS - immediate change to discrete
IGD - immediate change to IGD
DDIS - delayed change to discrete
DIGD - delayed change to IGD
ON - turn on not in use
OFF - turn off not in use

Tested on W500 (Intel/ATI) and T500 (Intel/ATI)

Signed-off-by: Dave Airlie <airlied@redhat.com>

drivers/gpu/drm/radeon/radeon_bios.c

@@ -30,6 +30,7 @@
 #include "radeon.h"
 #include "atom.h"
 
+#include <linux/vga_switcheroo.h>
 /*
  * BIOS.
  */
@@ -62,7 +63,7 @@ static bool igp_read_bios_from_vram(struct radeon_device *rdev)
 		iounmap(bios);
 		return false;
 	}
-	memcpy(rdev->bios, bios, size);
+	memcpy_fromio(rdev->bios, bios, size);
 	iounmap(bios);
 	return true;
 }
@@ -93,6 +94,38 @@ static bool radeon_read_bios(struct radeon_device *rdev)
 	return true;
 }
 
+/* ATRM is used to get the BIOS on the discrete cards in
+ * dual-gpu systems.
+ */
+static bool radeon_atrm_get_bios(struct radeon_device *rdev)
+{
+	int ret;
+	int size = 64 * 1024;
+	int i;
+
+	if (!radeon_atrm_supported(rdev->pdev))
+		return false;
+
+	rdev->bios = kmalloc(size, GFP_KERNEL);
+	if (!rdev->bios) {
+		DRM_ERROR("Unable to allocate bios\n");
+		return false;
+	}
+
+	for (i = 0; i < size / ATRM_BIOS_PAGE; i++) {
+		ret = radeon_atrm_get_bios_chunk(rdev->bios,
+						 (i * ATRM_BIOS_PAGE),
+						 ATRM_BIOS_PAGE);
+		if (ret <= 0)
+			break;
+	}
+
+	if (i == 0 || rdev->bios[0] != 0x55 || rdev->bios[1] != 0xaa) {
+		kfree(rdev->bios);
+		return false;
+	}
+	return true;
+}
 static bool r700_read_disabled_bios(struct radeon_device *rdev)
 {
 	uint32_t viph_control;
@@ -388,16 +421,16 @@ static bool radeon_read_disabled_bios(struct radeon_device *rdev)
 		return legacy_read_disabled_bios(rdev);
 }
 
+
 bool radeon_get_bios(struct radeon_device *rdev)
 {
 	bool r;
 	uint16_t tmp;
 
-	if (rdev->flags & RADEON_IS_IGP) {
+	r = radeon_atrm_get_bios(rdev);
+	if (r == false)
 		r = igp_read_bios_from_vram(rdev);
-		if (r == false)
-			r = radeon_read_bios(rdev);
-	} else
+	if (r == false)
 		r = radeon_read_bios(rdev);
 	if (r == false) {
 		r = radeon_read_disabled_bios(rdev);
@@ -408,6 +441,7 @@ bool radeon_get_bios(struct radeon_device *rdev)
 		return false;
 	}
 	if (rdev->bios[0] != 0x55 || rdev->bios[1] != 0xaa) {
+		printk("BIOS signature incorrect %x %x\n", rdev->bios[0], rdev->bios[1]);
 		goto free_bios;
 	}