drm/i915: Type safe register read/write

Make I915_READ and I915_WRITE more type safe by wrapping the register
offset in a struct. This should eliminate most of the fumbles we've had
with misplaced parens.

This only takes care of normal mmio registers. We could extend the idea
to other register types and define each with its own struct. That way
you wouldn't be able to accidentally pass the wrong thing to a specific
register access function.

The gpio_reg setup is probably the ugliest thing left. But I figure I'd
just leave it for now, and wait for some divine inspiration to strike
before making it nice.

As for the generated code, it's actually a bit better sometimes. Eg.
looking at i915_irq_handler(), we can see the following change:
  lea    0x70024(%rdx,%rax,1),%r9d
  mov    $0x1,%edx
- movslq %r9d,%r9
- mov    %r9,%rsi
- mov    %r9,-0x58(%rbp)
- callq  *0xd8(%rbx)
+ mov    %r9d,%esi
+ mov    %r9d,-0x48(%rbp)
 callq  *0xd8(%rbx)

So previously gcc thought the register offset might be signed and
decided to sign extend it, just in case. The rest appears to be
mostly just minor shuffling of instructions.

v2: i915_mmio_reg_{offset,equal,valid}() helpers added
    s/_REG/_MMIO/ in the register defines
    mo more switch statements left to worry about
    ring_emit stuff got sorted in a prep patch
    cmd parser, lrc context and w/a batch buildup also in prep patch
    vgpu stuff cleaned up and moved to a prep patch
    all other unrelated changes split out
v3: Rebased due to BXT DSI/BLC, MOCS, etc.
v4: Rebased due to churn, s/i915_mmio_reg_t/i915_reg_t/

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Link: http://patchwork.freedesktop.org/patch/msgid/1447853606-2751-1-git-send-email-ville.syrjala@linux.intel.com

1 files changed, 8 insertions, 5 deletions

diff --git a/drivers/gpu/drm/i915/intel_ringbuffer.c b/drivers/gpu/drm/i915/intel_ringbuffer.c
index 75f29d81af16..b9e7f6931f4e 100644
--- a/drivers/gpu/drm/i915/intel_ringbuffer.c
+++ b/drivers/gpu/drm/i915/intel_ringbuffer.c
@@ -479,7 +479,7 @@ static void intel_ring_setup_status_page(struct intel_engine_cs *ring)
 {
 	struct drm_device *dev = ring->dev;
 	struct drm_i915_private *dev_priv = ring->dev->dev_private;
-	u32 mmio = 0;
+	i915_reg_t mmio;
 
 	/* The ring status page addresses are no longer next to the rest of
 	 * the ring registers as of gen7.
@@ -522,7 +522,7 @@ static void intel_ring_setup_status_page(struct intel_engine_cs *ring)
 	 * invalidating the TLB?
 	 */
 	if (INTEL_INFO(dev)->gen >= 6 && INTEL_INFO(dev)->gen < 8) {
-		u32 reg = RING_INSTPM(ring->mmio_base);
+		i915_reg_t reg = RING_INSTPM(ring->mmio_base);
 
 		/* ring should be idle before issuing a sync flush*/
 		WARN_ON((I915_READ_MODE(ring) & MODE_IDLE) == 0);
@@ -764,7 +764,8 @@ static int intel_rcs_ctx_init(struct drm_i915_gem_request *req)
 }
 
 static int wa_add(struct drm_i915_private *dev_priv,
-		  const u32 addr, const u32 mask, const u32 val)
+		  i915_reg_t addr,
+		  const u32 mask, const u32 val)
 {
 	const u32 idx = dev_priv->workarounds.count;
 
@@ -1309,9 +1310,11 @@ static int gen6_signal(struct drm_i915_gem_request *signaller_req,
 		return ret;
 
 	for_each_ring(useless, dev_priv, i) {
-		u32 mbox_reg = signaller->semaphore.mbox.signal[i];
-		if (mbox_reg != GEN6_NOSYNC) {
+		i915_reg_t mbox_reg = signaller->semaphore.mbox.signal[i];
+
+		if (i915_mmio_reg_valid(mbox_reg)) {
 			u32 seqno = i915_gem_request_get_seqno(signaller_req);
+
 			intel_ring_emit(signaller, MI_LOAD_REGISTER_IMM(1));
 			intel_ring_emit_reg(signaller, mbox_reg);
 			intel_ring_emit(signaller, seqno);