drm/radeon: add spinlocks for indirect register accesss

This adds spinlocks to protect access to other
indirect register apertures.  These indirect spaces are
used pretty infrequently and we haven't had an reported
problems, but better safe than sorry.

Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
diff --git a/drivers/gpu/drm/radeon/r600.c b/drivers/gpu/drm/radeon/r600.c
index ea4d3734..11cd99e 100644
--- a/drivers/gpu/drm/radeon/r600.c
+++ b/drivers/gpu/drm/radeon/r600.c
@@ -1045,20 +1045,27 @@
 
 uint32_t rs780_mc_rreg(struct radeon_device *rdev, uint32_t reg)
 {
+	unsigned long flags;
 	uint32_t r;
 
+	spin_lock_irqsave(&rdev->mc_idx_lock, flags);
 	WREG32(R_0028F8_MC_INDEX, S_0028F8_MC_IND_ADDR(reg));
 	r = RREG32(R_0028FC_MC_DATA);
 	WREG32(R_0028F8_MC_INDEX, ~C_0028F8_MC_IND_ADDR);
+	spin_unlock_irqrestore(&rdev->mc_idx_lock, flags);
 	return r;
 }
 
 void rs780_mc_wreg(struct radeon_device *rdev, uint32_t reg, uint32_t v)
 {
+	unsigned long flags;
+
+	spin_lock_irqsave(&rdev->mc_idx_lock, flags);
 	WREG32(R_0028F8_MC_INDEX, S_0028F8_MC_IND_ADDR(reg) |
 		S_0028F8_MC_IND_WR_EN(1));
 	WREG32(R_0028FC_MC_DATA, v);
 	WREG32(R_0028F8_MC_INDEX, 0x7F);
+	spin_unlock_irqrestore(&rdev->mc_idx_lock, flags);
 }
 
 static void r600_mc_program(struct radeon_device *rdev)
@@ -2092,20 +2099,27 @@
  */
 u32 r600_pciep_rreg(struct radeon_device *rdev, u32 reg)
 {
+	unsigned long flags;
 	u32 r;
 
+	spin_lock_irqsave(&rdev->pciep_idx_lock, flags);
 	WREG32(PCIE_PORT_INDEX, ((reg) & 0xff));
 	(void)RREG32(PCIE_PORT_INDEX);
 	r = RREG32(PCIE_PORT_DATA);
+	spin_unlock_irqrestore(&rdev->pciep_idx_lock, flags);
 	return r;
 }
 
 void r600_pciep_wreg(struct radeon_device *rdev, u32 reg, u32 v)
 {
+	unsigned long flags;
+
+	spin_lock_irqsave(&rdev->pciep_idx_lock, flags);
 	WREG32(PCIE_PORT_INDEX, ((reg) & 0xff));
 	(void)RREG32(PCIE_PORT_INDEX);
 	WREG32(PCIE_PORT_DATA, (v));
 	(void)RREG32(PCIE_PORT_DATA);
+	spin_unlock_irqrestore(&rdev->pciep_idx_lock, flags);
 }
 
 /*