[PATCH 3/3] drm/msm: gpu Add new gpu register read/write functions

[Jordan Crouse]

Add some new functions to manipulate GPU registers.  gpu_read64 and
gpu_write64 can read/write a 64 bit value to two 32 bit registers.
For 4XX and older these are normally perfcounter registers, but
future targets will use 64 bit addressing so there will be many
more spots where a 64 bit read and write are needed.

gpu_rmw() does a read/modify/write on a 32 bit register given a mask
and bits to OR in.

Signed-off-by: Jordan Crouse <jcrouse at codeaurora.org>
---
 drivers/gpu/drm/msm/adreno/a4xx_gpu.c | 12 ++---------
 drivers/gpu/drm/msm/msm_gpu.h         | 39 +++++++++++++++++++++++++++++++++++
 2 files changed, 41 insertions(+), 10 deletions(-)

diff --git a/drivers/gpu/drm/msm/adreno/a4xx_gpu.c b/drivers/gpu/drm/msm/adreno/a4xx_gpu.c
index ba16507..b82210c 100644
--- a/drivers/gpu/drm/msm/adreno/a4xx_gpu.c
+++ b/drivers/gpu/drm/msm/adreno/a4xx_gpu.c
@@ -513,16 +513,8 @@ static int a4xx_pm_suspend(struct msm_gpu *gpu) {
 
 static int a4xx_get_timestamp(struct msm_gpu *gpu, uint64_t *value)
 {
-	uint32_t hi, lo, tmp;
-
-	tmp = gpu_read(gpu, REG_A4XX_RBBM_PERFCTR_CP_0_HI);
-	do {
-		hi = tmp;
-		lo = gpu_read(gpu, REG_A4XX_RBBM_PERFCTR_CP_0_LO);
-		tmp = gpu_read(gpu, REG_A4XX_RBBM_PERFCTR_CP_0_HI);
-	} while (tmp != hi);
-
-	*value = (((uint64_t)hi) << 32) | lo;
+	*value = gpu_read64(gpu, REG_A4XX_RBBM_PERFCTR_CP_0_LO,
+		REG_A4XX_RBBM_PERFCTR_CP_0_HI);
 
 	return 0;
 }
diff --git a/drivers/gpu/drm/msm/msm_gpu.h b/drivers/gpu/drm/msm/msm_gpu.h
index 4ee95ca..f8e6657 100644
--- a/drivers/gpu/drm/msm/msm_gpu.h
+++ b/drivers/gpu/drm/msm/msm_gpu.h
@@ -154,6 +154,45 @@ static inline u32 gpu_read(struct msm_gpu *gpu, u32 reg)
 	return msm_readl(gpu->mmio + (reg << 2));
 }
 
+static inline void gpu_rmw(struct msm_gpu *gpu, u32 reg, u32 mask, u32 or)
+{
+	uint32_t val = gpu_read(gpu, reg);
+
+	val &= ~mask;
+	gpu_write(gpu, reg, val | or);
+}
+
+static inline u64 gpu_read64(struct msm_gpu *gpu, u32 lo, u32 hi)
+{
+	u64 val;
+
+	/*
+	 * Why not a readq here? Two reasons: 1) many of the LO registers are
+	 * not quad word aligned and 2) the GPU hardware designers have a bit
+	 * of a history of putting registers where they fit, especially in
+	 * spins. The longer a GPU family goes the higher the chance that
+	 * we'll get burned.  We could do a series of validity checks if we
+	 * wanted to, but really is a readq() that much better? Nah.
+	 */
+
+	/*
+	 * For some lo/hi registers (like perfcounters), the hi value is latched
+	 * when the lo is read, so make sure to read the lo first to trigger
+	 * that
+	 */
+	val = (u64) msm_readl(gpu->mmio + (lo << 2));
+	val |= ((u64) msm_readl(gpu->mmio + (hi << 2)) << 32);
+
+	return val;
+}
+
+static inline void gpu_write64(struct msm_gpu *gpu, u32 lo, u32 hi, u64 val)
+{
+	/* Why not a writeq here? Read the screed above */
+	msm_writel(lower_32_bits(val), gpu->mmio + (lo << 2));
+	msm_writel(upper_32_bits(val), gpu->mmio + (hi << 2));
+}
+
 int msm_gpu_pm_suspend(struct msm_gpu *gpu);
 int msm_gpu_pm_resume(struct msm_gpu *gpu);
 
-- 
1.9.1