With Lynx Point, we need to use SBI to communicate with the display clock
control. This commit adds helper functions to access the registers via
SBI.
v2: de-inline the function and address changes in bits names
v3: protect operations with dpio_lock, increase timeout to 100 for
paranoia sake.
v1 Reviewed-by: Rodrigo Vivi <rodrigo.vivi at gmail.com>
Signed-off-by: Eugeni Dodonov <eugeni.dodonov at intel.com>
---
drivers/gpu/drm/i915/intel_display.c | 63 ++++++++++++++++++++++++++++++++++
1 file changed, 63 insertions(+)
diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index 33aaad3..36f6b8e 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -1300,6 +1300,69 @@ static void intel_disable_pll(struct drm_i915_private *dev_priv, enum pipe pipe)
POSTING_READ(reg);
}
+/* SBI access */
+static void
+intel_sbi_write(struct drm_i915_private *dev_priv, u16 reg, u32 value)
+{
+ unsigned long flags;
+
+ spin_lock_irqsave(&dev_priv->dpio_lock, flags);
+ if (wait_for_atomic_us((I915_READ(SBI_CTL_STAT) & SBI_READY) == 0,
+ 100)) {
+ DRM_ERROR("timeout waiting for SBI to become ready\n");
+ goto out_unlock;
+ }
+
+ I915_WRITE(SBI_ADDR,
+ (reg << 16));
+ I915_WRITE(SBI_DATA,
+ value);
+ I915_WRITE(SBI_CTL_STAT,
+ SBI_BUSY |
+ SBI_CTL_OP_CRWR);
+
+ if (wait_for_atomic_us((I915_READ(SBI_CTL_STAT) & (SBI_READY | SBI_RESPONSE_SUCCESS)) == 0,
+ 100)) {
+ DRM_ERROR("timeout waiting for SBI to complete write transaction\n");
+ goto out_unlock;
+ }
+
+out_unlock:
+ spin_unlock_irqrestore(&dev_priv->dpio_lock, flags);
+}
+
+static u32
+intel_sbi_read(struct drm_i915_private *dev_priv, u16 reg)
+{
+ unsigned long flags;
+ u32 value;
+
+ spin_lock_irqsave(&dev_priv->dpio_lock, flags);
+ if (wait_for_atomic_us((I915_READ(SBI_CTL_STAT) & SBI_READY) == 0,
+ 100)) {
+ DRM_ERROR("timeout waiting for SBI to become ready\n");
+ goto out_unlock;
+ }
+
+ I915_WRITE(SBI_ADDR,
+ (reg << 16));
+ I915_WRITE(SBI_CTL_STAT,
+ SBI_BUSY |
+ SBI_CTL_OP_CRRD);
+
+ if (wait_for_atomic_us((I915_READ(SBI_CTL_STAT) & (SBI_READY | SBI_RESPONSE_SUCCESS)) == 0,
+ 100)) {
+ DRM_ERROR("timeout waiting for SBI to complete read transaction\n");
+ goto out_unlock;
+ }
+
+ value = I915_READ(SBI_DATA);
+
+out_unlock:
+ spin_unlock_irqrestore(&dev_priv->dpio_lock, flags);
+ return value;
+}
+
/**
* intel_enable_pch_pll - enable PCH PLL
* @dev_priv: i915 private structure
--
1.7.10
