[PATCH v4 3/8] drm/i915: Decode system memory bandwidth

["Kumar, Mahesh" <mahesh1.kumar@intel.com>]

This patch adds support to decode system memory bandwidth
which will be used for arbitrated display memory percentage
calculation in GEN9 based system.

Changes from v1:
 - Address comments from Paulo
 - implement decode function for SKL/KBL also

Signed-off-by: "Kumar, Mahesh" <mahesh1.kumar@intel.com>
---
 drivers/gpu/drm/i915/i915_drv.c | 170 ++++++++++++++++++++++++++++++++++++++++
 drivers/gpu/drm/i915/i915_drv.h |  14 ++++
 drivers/gpu/drm/i915/i915_reg.h |  38 +++++++++
 3 files changed, 222 insertions(+)

diff --git a/drivers/gpu/drm/i915/i915_drv.c b/drivers/gpu/drm/i915/i915_drv.c
index 89d3222..b5f601c 100644
--- a/drivers/gpu/drm/i915/i915_drv.c
+++ b/drivers/gpu/drm/i915/i915_drv.c
@@ -979,6 +979,170 @@ static void intel_sanitize_options(struct drm_i915_private *dev_priv)
 	DRM_DEBUG_DRIVER("use GPU sempahores? %s\n", yesno(i915.semaphores));
 }
 
+static inline void skl_memdev_info_fill(struct memdev_info *info, uint32_t val)
+{
+	uint8_t channel_width, rank;
+
+	info->rank_valid = true;
+	channel_width = (val >> SKL_DRAM_CHANNEL_WIDTH_SHIFT) &
+		SKL_DRAM_CHANNEL_WIDTH_MASK;
+	if (channel_width == SKL_DRAM_WIDTH_1)
+		info->channel_width_bytes = 1;
+	else if (channel_width == SKL_DRAM_WIDTH_2)
+		info->channel_width_bytes = 2;
+	else
+		info->channel_width_bytes = 4;
+
+	rank = (val >> SKL_DRAM_RANK_SHIFT) & SKL_DRAM_RANK_MASK;
+	if (rank == SKL_DRAM_RANK_SINGLE)
+		info->rank = DRAM_RANK_SINGLE;
+	else
+		info->rank = DRAM_RANK_DUAL;
+}
+
+static int
+skl_get_memdev_info(struct drm_i915_private *dev_priv)
+{
+	uint32_t val = 0;
+	uint32_t mem_speed = 0;
+	struct memdev_info *memdev_info = &dev_priv->memdev_info;
+
+	val = I915_READ(SKL_MC_BIOS_DATA_0_0_0_MCHBAR_PCU);
+	mem_speed = div_u64((uint64_t) (val & SKL_REQ_DATA_MASK) *
+			SKL_MEMORY_FREQ_MULTIPLIER, 1000);
+
+	if (mem_speed == 0)
+		return -EINVAL;
+
+	memdev_info->valid = true;
+	memdev_info->mem_speed_khz = mem_speed;
+	memdev_info->num_channels  = 0;
+
+	memdev_info->rank_valid = false;
+	val = I915_READ(SKL_MAD_DIMM_CH0_0_0_0_MCHBAR_MCMAIN);
+
+	if (val != 0xFFFFFFFF) {
+		memdev_info->num_channels++;
+		skl_memdev_info_fill(memdev_info, val);
+	}
+
+	val = I915_READ(SKL_MAD_DIMM_CH1_0_0_0_MCHBAR_MCMAIN);
+
+	if (val != 0xFFFFFFFF) {
+		memdev_info->num_channels++;
+		if (!memdev_info->rank_valid)
+			skl_memdev_info_fill(memdev_info, val);
+	}
+
+	if (memdev_info->num_channels == 0)
+		memdev_info->valid = false;
+	return 0;
+}
+
+static int
+bxt_get_memdev_info(struct drm_i915_private *dev_priv)
+{
+	struct memdev_info *memdev_info = &dev_priv->memdev_info;
+	uint32_t dram_channel;
+	uint32_t mem_speed, val;
+	uint8_t num_channel, dram_type;
+	int i;
+
+	val = I915_READ(BXT_P_CR_MC_BIOS_REQ_0_0_0);
+	mem_speed = div_u64((uint64_t) (val & BXT_REQ_DATA_MASK) *
+			SKL_MEMORY_FREQ_MULTIPLIER, 1000);
+
+	if (mem_speed == 0)
+		return -EINVAL;
+
+	memdev_info->valid = true;
+	memdev_info->mem_speed_khz = mem_speed;
+	dram_type = (val >> BXT_DRAM_TYPE_SHIFT) & BXT_DRAM_TYPE_MASK;
+	dram_channel = (val >> BXT_DRAM_CHANNEL_SHIFT) & BXT_DRAM_CHANNEL_MASK;
+	num_channel = hweight32(dram_channel);
+
+	/*
+	 * The lpddr3 and lpddr4 technologies can have 1-4 channels and the
+	 * channels are 32bits wide; while ddr3l technologies can have 1-2
+	 * channels and the channels are 64 bits wide. In case of single 64 bit
+	 * wide DDR3L dimm sets two channel-active bits in
+	 * P_CR_MC_BIOS_REQ_0_0_0 register and system with two DDR3L 64bit dimm
+	 * will set all four channel-active bits in above register.
+	 * In order to get actual number of channels in DDR3L DRAM we need to
+	 * device total channel-active bits set by 2.
+	 */
+
+	switch (dram_type) {
+	case BXT_DRAM_TYPE_LPDDR3:
+	case BXT_DRAM_TYPE_LPDDR4:
+		memdev_info->channel_width_bytes = 4;
+		memdev_info->num_channels = num_channel;
+		break;
+	case BXT_DRAM_TYPE_DDR3L:
+		memdev_info->channel_width_bytes = 8;
+		memdev_info->num_channels = num_channel / 2;
+		break;
+	default:
+		DRM_DEBUG_KMS("Unknown DRAM type\n");
+		memdev_info->valid = false;
+		return -EINVAL;
+	}
+
+	/*
+	 * Now read each DUNIT8/9/10/11 to check the rank of each dimms.
+	 * all the dimms should have same rank as in first valid Dimm
+	 */
+	memdev_info->rank_valid = false;
+	for (i = 0; i < BXT_D_CR_DRP0_DUNIT_MAX; i++) {
+		val = I915_READ(BXT_D_CR_DRP0_DUNIT(i));
+		if (val != 0xFFFFFFFF) {
+			uint8_t rank;
+
+			memdev_info->rank_valid = true;
+			rank = val & BXT_DRAM_RANK_MASK;
+			if (rank == BXT_DRAM_RANK_SINGLE)
+				memdev_info->rank = DRAM_RANK_SINGLE;
+			else if (rank == BXT_DRAM_RANK_DUAL)
+				memdev_info->rank = DRAM_RANK_DUAL;
+			else
+				memdev_info->rank = DRAM_RANK_NONE;
+
+			break;
+		}
+	}
+	return 0;
+}
+
+static void
+intel_get_memdev_info(struct drm_i915_private *dev_priv)
+{
+	struct memdev_info *memdev_info = &dev_priv->memdev_info;
+	int ret;
+
+	memdev_info->valid = false;
+	if (!IS_GEN9(dev_priv))
+		return;
+
+	if (IS_BROXTON(dev_priv))
+		ret = bxt_get_memdev_info(dev_priv);
+	else
+		ret = skl_get_memdev_info(dev_priv);
+	if (ret)
+		return;
+
+	if (memdev_info->valid) {
+		DRM_DEBUG_DRIVER("DRAM speed-%d Khz total-channels-%d channel-width-%d bytes\n",
+				memdev_info->mem_speed_khz,
+				memdev_info->num_channels,
+				memdev_info->channel_width_bytes);
+		if (memdev_info->rank_valid)
+			DRM_DEBUG_DRIVER("DRAM rank-%s\n",
+			(memdev_info->rank == DRAM_RANK_DUAL) ?
+						"dual" : "single");
+	}
+}
+
+
 /**
  * i915_driver_init_hw - setup state requiring device access
  * @dev_priv: device private
@@ -1082,6 +1246,12 @@ static int i915_driver_init_hw(struct drm_i915_private *dev_priv)
 			DRM_DEBUG_DRIVER("can't enable MSI");
 	}
 
+	/*
+	 * Fill the memdev structure to get the system raw bandwidth
+	 * This will be used by WM algorithm, to implement GEN9 based WA
+	 */
+	intel_get_memdev_info(dev_priv);
+
 	return 0;
 
 out_ggtt:
diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index a219a35..adbd9aa 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -2057,6 +2057,20 @@ struct drm_i915_private {
 		bool distrust_bios_wm;
 	} wm;
 
+	struct memdev_info {
+		bool valid;
+		uint32_t mem_speed_khz;
+		uint8_t channel_width_bytes;
+		uint8_t num_channels;
+		bool rank_valid;
+		enum {
+			DRAM_RANK_NONE = 0,
+			DRAM_RANK_SINGLE,
+			DRAM_RANK_DUAL
+		} rank;
+	} memdev_info;
+
+
 	struct i915_runtime_pm pm;
 
 	/* Abstract the submission mechanism (legacy ringbuffer or execlists) away */
diff --git a/drivers/gpu/drm/i915/i915_reg.h b/drivers/gpu/drm/i915/i915_reg.h
index acc767a..a9c467c 100644
--- a/drivers/gpu/drm/i915/i915_reg.h
+++ b/drivers/gpu/drm/i915/i915_reg.h
@@ -7721,6 +7721,44 @@ enum {
 #define  DC_STATE_DEBUG_MASK_CORES	(1<<0)
 #define  DC_STATE_DEBUG_MASK_MEMORY_UP	(1<<1)
 
+#define _MMIO_MCHBAR_PIPE(x, a, b)	_MMIO(MCHBAR_MIRROR_BASE_SNB + _PIPE(x, a, b))
+#define BXT_P_CR_MC_BIOS_REQ_0_0_0	_MMIO(MCHBAR_MIRROR_BASE_SNB + 0x7114)
+#define BXT_REQ_DATA_MASK		(0x3F << 0)
+#define BXT_DRAM_TYPE_SHIFT		24
+#define BXT_DRAM_TYPE_MASK		0x7
+#define BXT_DRAM_CHANNEL_SHIFT		12
+#define BXT_DRAM_CHANNEL_MASK		0xF
+
+#define BXT_DRAM_TYPE_LPDDR3		0x1
+#define BXT_DRAM_TYPE_LPDDR4		0x2
+#define BXT_DRAM_TYPE_DDR3L		0x4
+/*
+ * BIOS programs this field of REQ_DATA [5:0] in integer
+ * multiple of 133330 KHz (133.33MHz)
+ */
+#define	SKL_MEMORY_FREQ_MULTIPLIER		0x208D2
+#define BXT_D_CR_DRP0_DUNIT8			0x1000
+#define BXT_D_CR_DRP0_DUNIT9			0x1200
+#define BXT_D_CR_DRP0_DUNIT_MAX			4
+#define BXT_D_CR_DRP0_DUNIT(x)	_MMIO_MCHBAR_PIPE(x, 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 SKL_MC_BIOS_DATA_0_0_0_MCHBAR_PCU	_MMIO(MCHBAR_MIRROR_BASE_SNB + 0x5E04)
+#define SKL_REQ_DATA_MASK			(0xF << 0)
+#define SKL_MAD_DIMM_CH0_0_0_0_MCHBAR_MCMAIN	_MMIO(MCHBAR_MIRROR_BASE_SNB + 0x500C)
+#define SKL_MAD_DIMM_CH1_0_0_0_MCHBAR_MCMAIN	_MMIO(MCHBAR_MIRROR_BASE_SNB + 0x5010)
+#define SKL_DRAM_CHANNEL_WIDTH_MASK		0x3
+#define SKL_DRAM_CHANNEL_WIDTH_SHIFT		8
+#define SKL_DRAM_WIDTH_1			0x0
+#define SKL_DRAM_WIDTH_2			0x1
+#define SKL_DRAM_WIDTH_4			0x2
+#define SKL_DRAM_RANK_MASK			0x1
+#define SKL_DRAM_RANK_SHIFT			10
+#define SKL_DRAM_RANK_SINGLE			0x0
+#define SKL_DRAM_RANK_DUAL			0x1
+
 /* 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)
-- 
2.10.1

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