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, 7 insertions, 6 deletions

diff --git a/drivers/gpu/drm/i915/intel_ddi.c b/drivers/gpu/drm/i915/intel_ddi.c
index 4b111a1c552c..acc5b5a898fa 100644
--- a/drivers/gpu/drm/i915/intel_ddi.c
+++ b/drivers/gpu/drm/i915/intel_ddi.c
@@ -345,7 +345,7 @@ enum port intel_ddi_get_encoder_port(struct intel_encoder *intel_encoder)
 static bool
 intel_dig_port_supports_hdmi(const struct intel_digital_port *intel_dig_port)
 {
-	return intel_dig_port->hdmi.hdmi_reg;
+	return i915_mmio_reg_valid(intel_dig_port->hdmi.hdmi_reg);
 }
 
 static const struct ddi_buf_trans *skl_get_buf_trans_dp(struct drm_device *dev,
@@ -576,7 +576,7 @@ void intel_prepare_ddi(struct drm_device *dev)
 static void intel_wait_ddi_buf_idle(struct drm_i915_private *dev_priv,
 				    enum port port)
 {
-	uint32_t reg = DDI_BUF_CTL(port);
+	i915_reg_t reg = DDI_BUF_CTL(port);
 	int i;
 
 	for (i = 0; i < 16; i++) {
@@ -931,7 +931,8 @@ static void hsw_wrpll_update_rnp(uint64_t freq2k, unsigned budget,
 	/* Otherwise a < c && b >= d, do nothing */
 }
 
-static int hsw_ddi_calc_wrpll_link(struct drm_i915_private *dev_priv, int reg)
+static int hsw_ddi_calc_wrpll_link(struct drm_i915_private *dev_priv,
+				   i915_reg_t reg)
 {
 	int refclk = LC_FREQ;
 	int n, p, r;
@@ -967,7 +968,7 @@ static int hsw_ddi_calc_wrpll_link(struct drm_i915_private *dev_priv, int reg)
 static int skl_calc_wrpll_link(struct drm_i915_private *dev_priv,
 			       uint32_t dpll)
 {
-	uint32_t cfgcr1_reg, cfgcr2_reg;
+	i915_reg_t cfgcr1_reg, cfgcr2_reg;
 	uint32_t cfgcr1_val, cfgcr2_val;
 	uint32_t p0, p1, p2, dco_freq;
 
@@ -1930,7 +1931,7 @@ void intel_ddi_enable_transcoder_func(struct drm_crtc *crtc)
 void intel_ddi_disable_transcoder_func(struct drm_i915_private *dev_priv,
 				       enum transcoder cpu_transcoder)
 {
-	uint32_t reg = TRANS_DDI_FUNC_CTL(cpu_transcoder);
+	i915_reg_t reg = TRANS_DDI_FUNC_CTL(cpu_transcoder);
 	uint32_t val = I915_READ(reg);
 
 	val &= ~(TRANS_DDI_FUNC_ENABLE | TRANS_DDI_PORT_MASK | TRANS_DDI_DP_VC_PAYLOAD_ALLOC);
@@ -2507,7 +2508,7 @@ static const char * const skl_ddi_pll_names[] = {
 };
 
 struct skl_dpll_regs {
-	u32 ctl, cfgcr1, cfgcr2;
+	i915_reg_t ctl, cfgcr1, cfgcr2;
 };
 
 /* this array is indexed by the *shared* pll id */