drm/nouveau/pbus: add a PBUS subdev that hands IRQs to the right subdevs

We are going to use PTHERM's IRQs for thermal monitoring but we need to route
them first.

On nv31-50, PBUS's IRQ line is shared with GPIOs IRQs.

It seems like nv10-31 GPIO interruptions aren't well handled. I kept the
original behaviour but it is wrong and may lead to an IRQ storm.

Since we enable all PBUS IRQs, we need a way to avoid being stormed if we
don't handle them. The solution I used was to mask the IRQs that have not been
handled. This will also print one message in the logs to let us know.

v2: drop the shared intr handler because of was racy
v3: style fixes
v4: drop a useless construct in the chipset-dependent INTR
v5: add BUS to the disable mask
v6 (Ben Skeggs):
- general tidy to match the rest of the driver's style
- nva3->nvc0, nva3 can be serviced just fine with nv50.c, rnndb even notes
  that the THERM_ALARM bit got left in the hw until fermi anyway.. so, it's
  not going to conflict
- removed the peephole and user stuff, for the moment.. will handle them
  later if we find a good reason to actually care..
- limited INTR_EN to just what we can handle for now, mostly to prevent
  spam of unknown status bits (seen on at least nv4x)

Signed-off-by: Ben Skeggs <bskeggs@redhat.com>
Signed-off-by: Martin Peres <martin.peres@labri.fr>
diff --git a/drivers/gpu/drm/nouveau/core/subdev/bus/nv04.c b/drivers/gpu/drm/nouveau/core/subdev/bus/nv04.c
new file mode 100644
index 0000000..0c224e3
--- /dev/null
+++ b/drivers/gpu/drm/nouveau/core/subdev/bus/nv04.c
@@ -0,0 +1,95 @@
+/*
+ * Copyright 2012 Nouveau Community
+ *
+ * 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 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 HOLDER(S) OR AUTHOR(S) 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: Martin Peres <martin.peres@labri.fr>
+ *          Ben Skeggs
+ */
+
+#include <subdev/bus.h>
+
+struct nv04_bus_priv {
+	struct nouveau_bus base;
+};
+
+void
+nv04_bus_intr(struct nouveau_subdev *subdev)
+{
+	struct nouveau_bus *pbus = nouveau_bus(subdev);
+	u32 stat = nv_rd32(pbus, 0x001100) & nv_rd32(pbus, 0x001140);
+
+	if (stat & 0x00000001) {
+		nv_error(pbus, "BUS ERROR\n");
+		stat &= ~0x00000001;
+		nv_wr32(pbus, 0x001100, 0x00000001);
+	}
+
+	if (stat & 0x00000110) {
+		subdev = nouveau_subdev(subdev, NVDEV_SUBDEV_GPIO);
+		if (subdev && subdev->intr)
+			subdev->intr(subdev);
+		stat &= ~0x00000110;
+		nv_wr32(pbus, 0x001100, 0x00000110);
+	}
+
+	if (stat) {
+		nv_error(pbus, "unknown intr 0x%08x\n", stat);
+		nv_mask(pbus, 0x001140, stat, 0x00000000);
+	}
+}
+
+static int
+nv04_bus_ctor(struct nouveau_object *parent, struct nouveau_object *engine,
+	      struct nouveau_oclass *oclass, void *data, u32 size,
+	      struct nouveau_object **pobject)
+{
+	struct nv04_bus_priv *priv;
+	int ret;
+
+	ret = nouveau_bus_create(parent, engine, oclass, &priv);
+	*pobject = nv_object(priv);
+	if (ret)
+		return ret;
+
+	nv_subdev(priv)->intr = nv04_bus_intr;
+	return 0;
+}
+
+static int
+nv04_bus_init(struct nouveau_object *object)
+{
+	struct nv04_bus_priv *priv = (void *)object;
+
+	nv_wr32(priv, 0x001100, 0xffffffff);
+	nv_wr32(priv, 0x001140, 0x00000111);
+
+	return nouveau_bus_init(&priv->base);
+}
+
+struct nouveau_oclass
+nv04_bus_oclass = {
+	.handle = NV_SUBDEV(BUS, 0x04),
+	.ofuncs = &(struct nouveau_ofuncs) {
+		.ctor = nv04_bus_ctor,
+		.dtor = _nouveau_bus_dtor,
+		.init = nv04_bus_init,
+		.fini = _nouveau_bus_fini,
+	},
+};