drm/nouveau/gk20a: reclocking support

Add support for reclocking on GK20A, using a statically-defined pstates
table. The algorithms for calculating the coefficients and setting the
clocks are directly taken from the ChromeOS kernel.
Signed-off-by: Alexandre Courbot <acourbot@nvidia.com>
Signed-off-by: Ben Skeggs <bskeggs@redhat.com>

drivers/gpu/drm/nouveau/Makefile

@@ -65,6 +65,7 @@ nouveau-y += core/subdev/clock/nva3.o
 nouveau-y += core/subdev/clock/nvaa.o
 nouveau-y += core/subdev/clock/nvc0.o
 nouveau-y += core/subdev/clock/nve0.o
+nouveau-y += core/subdev/clock/gk20a.o
 nouveau-y += core/subdev/clock/pllnv04.o
 nouveau-y += core/subdev/clock/pllnva3.o
 nouveau-y += core/subdev/devinit/base.o

drivers/gpu/drm/nouveau/core/engine/device/nve0.c

@@ -158,6 +158,7 @@ nve0_identify(struct nouveau_device *device)
 		break;
 	case 0xea:
 		device->cname = "GK20A";
+		device->oclass[NVDEV_SUBDEV_CLOCK  ] = &gk20a_clock_oclass;
 		device->oclass[NVDEV_SUBDEV_MC     ] =  gk20a_mc_oclass;
 		device->oclass[NVDEV_SUBDEV_BUS    ] =  nvc0_bus_oclass;
 		device->oclass[NVDEV_SUBDEV_TIMER  ] = &gk20a_timer_oclass;

drivers/gpu/drm/nouveau/core/include/subdev/clock.h

@@ -147,6 +147,7 @@ extern struct nouveau_oclass *nvaa_clock_oclass;
 extern struct nouveau_oclass nva3_clock_oclass;
 extern struct nouveau_oclass nvc0_clock_oclass;
 extern struct nouveau_oclass nve0_clock_oclass;
+extern struct nouveau_oclass gk20a_clock_oclass;
 
 int nv04_clock_pll_set(struct nouveau_clock *, u32 type, u32 freq);
 int nv04_clock_pll_calc(struct nouveau_clock *, struct nvbios_pll *,

drivers/gpu/drm/nouveau/core/os.h

@@ -22,6 +22,7 @@
 #include <linux/log2.h>
 #include <linux/pm_runtime.h>
 #include <linux/power_supply.h>
+#include <linux/clk.h>
 
 #include <asm/unaligned.h>