drm/i915/bxt: Decode memory bandwidth and parameters

This patch adds support to decode system memory bandwidth and other
parameters for broxton platform, which will be used for arbitrated
display memory bandwidth calculation in GEN9 based platforms and
WM latency level-0 Work-around calculation on GEN9+ platforms.

Changes since V1:
 - s/memdev_info/dram_info
Changes since V2:
 - Adhere to i915 coding style (Rodrigo)

Signed-off-by: Mahesh Kumar <mahesh1.kumar@intel.com>
Reviewed-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20180824093225.12598-2-mahesh1.kumar@intel.com

drivers/gpu/drm/i915/i915_drv.c

@@ -1063,6 +1063,117 @@ static void intel_sanitize_options(struct drm_i915_private *dev_priv)
 	intel_gvt_sanitize_options(dev_priv);
 }
 
+static int
+bxt_get_dram_info(struct drm_i915_private *dev_priv)
+{
+	struct dram_info *dram_info = &dev_priv->dram_info;
+	u32 dram_channels;
+	u32 mem_freq_khz, val;
+	u8 num_active_channels;
+	int i;
+
+	val = I915_READ(BXT_P_CR_MC_BIOS_REQ_0_0_0);
+	mem_freq_khz = DIV_ROUND_UP((val & BXT_REQ_DATA_MASK) *
+				    BXT_MEMORY_FREQ_MULTIPLIER_HZ, 1000);
+
+	dram_channels = val & BXT_DRAM_CHANNEL_ACTIVE_MASK;
+	num_active_channels = hweight32(dram_channels);
+
+	/* Each active bit represents 4-byte channel */
+	dram_info->bandwidth_kbps = (mem_freq_khz * num_active_channels * 4);
+
+	if (dram_info->bandwidth_kbps == 0) {
+		DRM_INFO("Couldn't get system memory bandwidth\n");
+		return -EINVAL;
+	}
+
+	/*
+	 * Now read each DUNIT8/9/10/11 to check the rank of each dimms.
+	 */
+	for (i = BXT_D_CR_DRP0_DUNIT_START; i <= BXT_D_CR_DRP0_DUNIT_END; i++) {
+		u8 size, width;
+		enum dram_rank rank;
+		u32 tmp;
+
+		val = I915_READ(BXT_D_CR_DRP0_DUNIT(i));
+		if (val == 0xFFFFFFFF)
+			continue;
+
+		dram_info->num_channels++;
+		tmp = val & BXT_DRAM_RANK_MASK;
+
+		if (tmp == BXT_DRAM_RANK_SINGLE)
+			rank = I915_DRAM_RANK_SINGLE;
+		else if (tmp == BXT_DRAM_RANK_DUAL)
+			rank = I915_DRAM_RANK_DUAL;
+		else
+			rank = I915_DRAM_RANK_INVALID;
+
+		tmp = val & BXT_DRAM_SIZE_MASK;
+		if (tmp == BXT_DRAM_SIZE_4GB)
+			size = 4;
+		else if (tmp == BXT_DRAM_SIZE_6GB)
+			size = 6;
+		else if (tmp == BXT_DRAM_SIZE_8GB)
+			size = 8;
+		else if (tmp == BXT_DRAM_SIZE_12GB)
+			size = 12;
+		else if (tmp == BXT_DRAM_SIZE_16GB)
+			size = 16;
+		else
+			size = 0;
+
+		tmp = (val & BXT_DRAM_WIDTH_MASK) >> BXT_DRAM_WIDTH_SHIFT;
+		width = (1 << tmp) * 8;
+		DRM_DEBUG_KMS("dram size:%dGB width:X%d rank:%s\n", size,
+			      width, rank == I915_DRAM_RANK_SINGLE ? "single" :
+			      rank == I915_DRAM_RANK_DUAL ? "dual" : "unknown");
+
+		/*
+		 * If any of the channel is single rank channel,
+		 * worst case output will be same as if single rank
+		 * memory, so consider single rank memory.
+		 */
+		if (dram_info->rank == I915_DRAM_RANK_INVALID)
+			dram_info->rank = rank;
+		else if (rank == I915_DRAM_RANK_SINGLE)
+			dram_info->rank = I915_DRAM_RANK_SINGLE;
+	}
+
+	if (dram_info->rank == I915_DRAM_RANK_INVALID) {
+		DRM_INFO("couldn't get memory rank information\n");
+		return -EINVAL;
+	}
+
+	dram_info->valid = true;
+	return 0;
+}
+
+static void
+intel_get_dram_info(struct drm_i915_private *dev_priv)
+{
+	struct dram_info *dram_info = &dev_priv->dram_info;
+	int ret;
+
+	dram_info->valid = false;
+	dram_info->rank = I915_DRAM_RANK_INVALID;
+	dram_info->bandwidth_kbps = 0;
+	dram_info->num_channels = 0;
+
+	if (!IS_BROXTON(dev_priv))
+		return;
+
+	ret = bxt_get_dram_info(dev_priv);
+	if (ret)
+		return;
+
+	DRM_DEBUG_KMS("DRAM bandwidth:%d KBps, total-channels: %u\n",
+		      dram_info->bandwidth_kbps, dram_info->num_channels);
+	DRM_DEBUG_KMS("DRAM rank: %s rank\n",
+		      (dram_info->rank == I915_DRAM_RANK_DUAL) ?
+		      "dual" : "single");
+}
+
 /**
  * i915_driver_init_hw - setup state requiring device access
  * @dev_priv: device private
@@ -1180,6 +1291,12 @@ static int i915_driver_init_hw(struct drm_i915_private *dev_priv)
 		goto err_msi;
 
 	intel_opregion_setup(dev_priv);
+	/*
+	 * Fill the dram structure to get the system raw bandwidth and
+	 * dram info. This will be used for memory latency calculation.
+	 */
+	intel_get_dram_info(dev_priv);
+
 
 	return 0;
 

drivers/gpu/drm/i915/i915_drv.h

@@ -1945,6 +1945,17 @@ struct drm_i915_private {
 		bool distrust_bios_wm;
 	} wm;
 
+	struct dram_info {
+		bool valid;
+		u8 num_channels;
+		enum dram_rank {
+			I915_DRAM_RANK_INVALID = 0,
+			I915_DRAM_RANK_SINGLE,
+			I915_DRAM_RANK_DUAL
+		} rank;
+		u32 bandwidth_kbps;
+	} dram_info;
+
 	struct i915_runtime_pm runtime_pm;
 
 	struct {

drivers/gpu/drm/i915/i915_reg.h

@@ -9583,6 +9583,36 @@ enum skl_power_gate {
 #define  DC_STATE_DEBUG_MASK_CORES	(1 << 0)
 #define  DC_STATE_DEBUG_MASK_MEMORY_UP	(1 << 1)
 
+#define BXT_P_CR_MC_BIOS_REQ_0_0_0	_MMIO(MCHBAR_MIRROR_BASE_SNB + 0x7114)
+#define  BXT_REQ_DATA_MASK			0x3F
+#define  BXT_DRAM_CHANNEL_ACTIVE_SHIFT		12
+#define  BXT_DRAM_CHANNEL_ACTIVE_MASK		(0xF << 12)
+#define  BXT_MEMORY_FREQ_MULTIPLIER_HZ		133333333
+
+#define BXT_D_CR_DRP0_DUNIT8			0x1000
+#define BXT_D_CR_DRP0_DUNIT9			0x1200
+#define  BXT_D_CR_DRP0_DUNIT_START		8
+#define  BXT_D_CR_DRP0_DUNIT_END		11
+#define BXT_D_CR_DRP0_DUNIT(x)	_MMIO(MCHBAR_MIRROR_BASE_SNB + \
+				      _PICK_EVEN((x) - 8, BXT_D_CR_DRP0_DUNIT8,\
+						 BXT_D_CR_DRP0_DUNIT9))
+#define  BXT_DRAM_RANK_MASK			0x3
+#define  BXT_DRAM_RANK_SINGLE			0x1
+#define  BXT_DRAM_RANK_DUAL			0x3
+#define  BXT_DRAM_WIDTH_MASK			(0x3 << 4)
+#define  BXT_DRAM_WIDTH_SHIFT			4
+#define  BXT_DRAM_WIDTH_X8			(0x0 << 4)
+#define  BXT_DRAM_WIDTH_X16			(0x1 << 4)
+#define  BXT_DRAM_WIDTH_X32			(0x2 << 4)
+#define  BXT_DRAM_WIDTH_X64			(0x3 << 4)
+#define  BXT_DRAM_SIZE_MASK			(0x7 << 6)
+#define  BXT_DRAM_SIZE_SHIFT			6
+#define  BXT_DRAM_SIZE_4GB			(0x0 << 6)
+#define  BXT_DRAM_SIZE_6GB			(0x1 << 6)
+#define  BXT_DRAM_SIZE_8GB			(0x2 << 6)
+#define  BXT_DRAM_SIZE_12GB			(0x3 << 6)
+#define  BXT_DRAM_SIZE_16GB			(0x4 << 6)
+
 /* Please see hsw_read_dcomp() and hsw_write_dcomp() before using this register,
  * since on HSW we can't write to it using I915_WRITE. */
 #define D_COMP_HSW			_MMIO(MCHBAR_MIRROR_BASE_SNB + 0x5F0C)