Merge tag 'memory-controller-drv-5.16-2' of git://git.kernel.org/pub/scm/linux/kernel/git/krzk/linux-mem-ctrl into arm/drivers

Memory controller drivers for v5.16, part two

1. Convert LPDDR2 bindings to dtschema and extend them with new
properties.
2. Tegra 20 EMC: support matching timings by LPDDR2 configuration from
devicetree.

* tag 'memory-controller-drv-5.16-2' of git://git.kernel.org/pub/scm/linux/kernel/git/krzk/linux-mem-ctrl:
memory: tegra20-emc: Add runtime dependency on devfreq governor module
memory: tegra20-emc: Support matching timings by LPDDR2 configuration
memory: Add LPDDR2-info helpers
dt-bindings: memory: tegra20: emc: Document new LPDDR2 sub-node
dt-bindings: Add vendor prefix for Elpida Memory
dt-bindings: memory: lpddr2: Document Elpida B8132B2PB-6D-F
dt-bindings: memory: lpddr2: Add revision-id properties
dt-bindings: memory: lpddr2: Convert to schema
dt-bindings: Relocate DDR bindings

Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Arnd Bergmann <[e-mail]>

Documentation/devicetree/bindings/ddr/lpddr2.txt

···
-* LPDDR2 SDRAM memories compliant to JEDEC JESD209-2
-
-Required properties:
-- compatible : Should be one of - "jedec,lpddr2-nvm", "jedec,lpddr2-s2",
-  "jedec,lpddr2-s4"
-
-  "ti,jedec-lpddr2-s2" should be listed if the memory part is LPDDR2-S2 type
-
-  "ti,jedec-lpddr2-s4" should be listed if the memory part is LPDDR2-S4 type
-
-  "ti,jedec-lpddr2-nvm" should be listed if the memory part is LPDDR2-NVM type
-
-- density  : <u32> representing density in Mb (Mega bits)
-
-- io-width : <u32> representing bus width. Possible values are 8, 16, and 32
-
-Optional properties:
-
-The following optional properties represent the minimum value of some AC
-timing parameters of the DDR device in terms of number of clock cycles.
-These values shall be obtained from the device data-sheet.
-- tRRD-min-tck
-- tWTR-min-tck
-- tXP-min-tck
-- tRTP-min-tck
-- tCKE-min-tck
-- tRPab-min-tck
-- tRCD-min-tck
-- tWR-min-tck
-- tRASmin-min-tck
-- tCKESR-min-tck
-- tFAW-min-tck
-
-Child nodes:
-- The lpddr2 node may have one or more child nodes of type "lpddr2-timings".
-  "lpddr2-timings" provides AC timing parameters of the device for
-  a given speed-bin. The user may provide the timings for as many
-  speed-bins as is required. Please see Documentation/devicetree/
-  bindings/ddr/lpddr2-timings.txt for more information on "lpddr2-timings"
-
-Example:
-
-elpida_ECB240ABACN : lpddr2 {
-	compatible	= "Elpida,ECB240ABACN","jedec,lpddr2-s4";
-	density		= <2048>;
-	io-width	= <32>;
-
-	tRPab-min-tck	= <3>;
-	tRCD-min-tck	= <3>;
-	tWR-min-tck	= <3>;
-	tRASmin-min-tck	= <3>;
-	tRRD-min-tck	= <2>;
-	tWTR-min-tck	= <2>;
-	tXP-min-tck	= <2>;
-	tRTP-min-tck	= <2>;
-	tCKE-min-tck	= <3>;
-	tCKESR-min-tck	= <3>;
-	tFAW-min-tck	= <8>;
-
-	timings_elpida_ECB240ABACN_400mhz: lpddr2-timings@0 {
-		compatible	= "jedec,lpddr2-timings";
-		min-freq	= <10000000>;
-		max-freq	= <400000000>;
-		tRPab		= <21000>;
-		tRCD		= <18000>;
-		tWR		= <15000>;
-		tRAS-min	= <42000>;
-		tRRD		= <10000>;
-		tWTR		= <7500>;
-		tXP		= <7500>;
-		tRTP		= <7500>;
-		tCKESR		= <15000>;
-		tDQSCK-max	= <5500>;
-		tFAW		= <50000>;
-		tZQCS		= <90000>;
-		tZQCL		= <360000>;
-		tZQinit		= <1000000>;
-		tRAS-max-ns	= <70000>;
-	};
-
-	timings_elpida_ECB240ABACN_200mhz: lpddr2-timings@1 {
-		compatible	= "jedec,lpddr2-timings";
-		min-freq	= <10000000>;
-		max-freq	= <200000000>;
-		tRPab		= <21000>;
-		tRCD		= <18000>;
-		tWR		= <15000>;
-		tRAS-min	= <42000>;
-		tRRD		= <10000>;
-		tWTR		= <10000>;
-		tXP		= <7500>;
-		tRTP		= <7500>;
-		tCKESR		= <15000>;
-		tDQSCK-max	= <5500>;
-		tFAW		= <50000>;
-		tZQCS		= <90000>;
-		tZQCL		= <360000>;
-		tZQinit		= <1000000>;
-		tRAS-max-ns	= <70000>;
-	};
-
-}

Documentation/devicetree/bindings/ddr/lpddr3.txt Documentation/devicetree/bindings/memory-controllers/ddr/lpddr3.txt

···
 Child nodes:
 - The lpddr3 node may have one or more child nodes of type "lpddr3-timings".
   "lpddr3-timings" provides AC timing parameters of the device for
-  a given speed-bin. Please see Documentation/devicetree/
-  bindings/ddr/lpddr3-timings.txt for more information on "lpddr3-timings"
+  a given speed-bin. Please see
+  Documentation/devicetree/bindings/memory-controllers/ddr/lpddr3-timings.txt
+  for more information on "lpddr3-timings"
 
 Example:
 

Documentation/devicetree/bindings/memory-controllers/ddr/jedec,lpddr2.yaml

···
+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/memory-controllers/ddr/jedec,lpddr2.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: LPDDR2 SDRAM compliant to JEDEC JESD209-2
+
+maintainers:
+  - Krzysztof Kozlowski <[e-mail]>
+
+properties:
+  compatible:
+    oneOf:
+      - items:
+          - enum:
+              - elpida,ECB240ABACN
+              - elpida,B8132B2PB-6D-F
+          - enum:
+              - jedec,lpddr2-s4
+      - items:
+          - enum:
+              - jedec,lpddr2-s2
+      - items:
+          - enum:
+              - jedec,lpddr2-nvm
+
+  revision-id1:
+    $ref: /schemas/types.yaml#/definitions/uint32
+    maximum: 255
+    description: |
+      Revision 1 value of SDRAM chip. Obtained from device datasheet.
+
+  revision-id2:
+    $ref: /schemas/types.yaml#/definitions/uint32
+    maximum: 255
+    description: |
+      Revision 2 value of SDRAM chip. Obtained from device datasheet.
+
+  density:
+    $ref: /schemas/types.yaml#/definitions/uint32
+    description: |
+      Density in megabits of SDRAM chip. Obtained from device datasheet.
+    enum:
+      - 64
+      - 128
+      - 256
+      - 512
+      - 1024
+      - 2048
+      - 4096
+      - 8192
+      - 16384
+      - 32768
+
+  io-width:
+    $ref: /schemas/types.yaml#/definitions/uint32
+    description: |
+      IO bus width in bits of SDRAM chip. Obtained from device datasheet.
+    enum:
+      - 32
+      - 16
+      - 8
+
+  tRRD-min-tck:
+    $ref: /schemas/types.yaml#/definitions/uint32
+    maximum: 16
+    description: |
+      Active bank a to active bank b in terms of number of clock cycles.
+      Obtained from device datasheet.
+
+  tWTR-min-tck:
+    $ref: /schemas/types.yaml#/definitions/uint32
+    maximum: 16
+    description: |
+      Internal WRITE-to-READ command delay in terms of number of clock cycles.
+      Obtained from device datasheet.
+
+  tXP-min-tck:
+    $ref: /schemas/types.yaml#/definitions/uint32
+    maximum: 16
+    description: |
+      Exit power-down to next valid command delay in terms of number of clock
+      cycles. Obtained from device datasheet.
+
+  tRTP-min-tck:
+    $ref: /schemas/types.yaml#/definitions/uint32
+    maximum: 16
+    description: |
+      Internal READ to PRECHARGE command delay in terms of number of clock
+      cycles. Obtained from device datasheet.
+
+  tCKE-min-tck:
+    $ref: /schemas/types.yaml#/definitions/uint32
+    maximum: 16
+    description: |
+      CKE minimum pulse width (HIGH and LOW pulse width) in terms of number
+      of clock cycles. Obtained from device datasheet.
+
+  tRPab-min-tck:
+    $ref: /schemas/types.yaml#/definitions/uint32
+    maximum: 16
+    description: |
+      Row precharge time (all banks) in terms of number of clock cycles.
+      Obtained from device datasheet.
+
+  tRCD-min-tck:
+    $ref: /schemas/types.yaml#/definitions/uint32
+    maximum: 16
+    description: |
+      RAS-to-CAS delay in terms of number of clock cycles. Obtained from
+      device datasheet.
+
+  tWR-min-tck:
+    $ref: /schemas/types.yaml#/definitions/uint32
+    maximum: 16
+    description: |
+      WRITE recovery time in terms of number of clock cycles. Obtained from
+      device datasheet.
+
+  tRASmin-min-tck:
+    $ref: /schemas/types.yaml#/definitions/uint32
+    maximum: 16
+    description: |
+      Row active time in terms of number of clock cycles. Obtained from device
+      datasheet.
+
+  tCKESR-min-tck:
+    $ref: /schemas/types.yaml#/definitions/uint32
+    maximum: 16
+    description: |
+      CKE minimum pulse width during SELF REFRESH (low pulse width during
+      SELF REFRESH) in terms of number of clock cycles. Obtained from device
+      datasheet.
+
+  tFAW-min-tck:
+    $ref: /schemas/types.yaml#/definitions/uint32
+    maximum: 16
+    description: |
+      Four-bank activate window in terms of number of clock cycles. Obtained
+      from device datasheet.
+
+patternProperties:
+  "^lpddr2-timings":
+    type: object
+    description: |
+      The lpddr2 node may have one or more child nodes of type "lpddr2-timings".
+      "lpddr2-timings" provides AC timing parameters of the device for
+      a given speed-bin. The user may provide the timings for as many
+      speed-bins as is required. Please see Documentation/devicetree/
+      bindings/memory-controllers/ddr/lpddr2-timings.txt for more information
+      on "lpddr2-timings".
+
+required:
+  - compatible
+  - density
+  - io-width
+
+additionalProperties: false
+
+examples:
+  - |
+    elpida_ECB240ABACN: lpddr2 {
+        compatible = "elpida,ECB240ABACN", "jedec,lpddr2-s4";
+        density = <2048>;
+        io-width = <32>;
+        revision-id1 = <1>;
+        revision-id2 = <0>;
+
+        tRPab-min-tck = <3>;
+        tRCD-min-tck = <3>;
+        tWR-min-tck = <3>;
+        tRASmin-min-tck = <3>;
+        tRRD-min-tck = <2>;
+        tWTR-min-tck = <2>;
+        tXP-min-tck = <2>;
+        tRTP-min-tck = <2>;
+        tCKE-min-tck = <3>;
+        tCKESR-min-tck = <3>;
+        tFAW-min-tck = <8>;
+
+        timings_elpida_ECB240ABACN_400mhz: lpddr2-timings0 {
+            compatible = "jedec,lpddr2-timings";
+            min-freq = <10000000>;
+            max-freq = <400000000>;
+            tRPab = <21000>;
+            tRCD = <18000>;
+            tWR = <15000>;
+            tRAS-min = <42000>;
+            tRRD = <10000>;
+            tWTR = <7500>;
+            tXP = <7500>;
+            tRTP = <7500>;
+            tCKESR = <15000>;
+            tDQSCK-max = <5500>;
+            tFAW = <50000>;
+            tZQCS = <90000>;
+            tZQCL = <360000>;
+            tZQinit = <1000000>;
+            tRAS-max-ns = <70000>;
+        };
+
+        timings_elpida_ECB240ABACN_200mhz: lpddr2-timings1 {
+            compatible = "jedec,lpddr2-timings";
+            min-freq = <10000000>;
+            max-freq = <200000000>;
+            tRPab = <21000>;
+            tRCD = <18000>;
+            tWR = <15000>;
+            tRAS-min = <42000>;
+            tRRD = <10000>;
+            tWTR = <10000>;
+            tXP = <7500>;
+            tRTP = <7500>;
+            tCKESR = <15000>;
+            tDQSCK-max = <5500>;
+            tFAW = <50000>;
+            tZQCS = <90000>;
+            tZQCL = <360000>;
+            tZQinit = <1000000>;
+            tRAS-max-ns = <70000>;
+        };
+    };

Documentation/devicetree/bindings/memory-controllers/nvidia,tegra20-emc.yaml

···
       "#size-cells":
         const: 0
 
+      lpddr2:
+        $ref: "ddr/jedec,lpddr2.yaml#"
+        type: object
+
     patternProperties:
       "^emc-table@[0-9]+$":
         $ref: "#/$defs/emc-table"
 
-    required:
-      - nvidia,ram-code
+    oneOf:
+      - required:
+          - nvidia,ram-code
+
+      - required:
+          - lpddr2
 
     additionalProperties: false
 
···
                         0x00000000 0x00000000 0x00000083 0xf0440303
                         0x007fe010 0x00001414 0x00000000 0x00000000
                         0x00000000 0x00000000 0x00000000 0x00000000>;
+            };
+        };
+
+        emc-tables@1 {
+            reg = <1>;
+
+            lpddr2 {
+                compatible = "elpida,B8132B2PB-6D-F", "jedec,lpddr2-s4";
+                revision-id1 = <1>;
+                density = <2048>;
+                io-width = <16>;
             };
         };
     };

Documentation/devicetree/bindings/memory-controllers/samsung,exynos5422-dmc.yaml

···
     $ref: '/schemas/types.yaml#/definitions/phandle'
     description: |
       phandle of the connected DRAM memory device. For more information please
-      refer to documentation file: Documentation/devicetree/bindings/ddr/lpddr3.txt
+      refer to documentation file:
+      Documentation/devicetree/bindings/memory-controllers/ddr/lpddr3.txt
 
   operating-points-v2: true
 

Documentation/devicetree/bindings/vendor-prefixes.yaml

···
     description: Shenzhen Elida Technology Co., Ltd.
   "^elimo,.*":
     description: Elimo Engineering Ltd.
+  "^elpida,.*":
+    description: Elpida Memory, Inc.
   "^embest,.*":
     description: Shenzhen Embest Technology Co., Ltd.
   "^emlid,.*":

drivers/memory/jedec_ddr.h

···
 #define NUM_DDR_ADDR_TABLE_ENTRIES			11
 #define NUM_DDR_TIMING_TABLE_ENTRIES			4
 
+#define LPDDR2_MANID_SAMSUNG				1
+#define LPDDR2_MANID_QIMONDA				2
+#define LPDDR2_MANID_ELPIDA				3
+#define LPDDR2_MANID_ETRON				4
+#define LPDDR2_MANID_NANYA				5
+#define LPDDR2_MANID_HYNIX				6
+#define LPDDR2_MANID_MOSEL				7
+#define LPDDR2_MANID_WINBOND				8
+#define LPDDR2_MANID_ESMT				9
+#define LPDDR2_MANID_SPANSION				11
+#define LPDDR2_MANID_SST				12
+#define LPDDR2_MANID_ZMOS				13
+#define LPDDR2_MANID_INTEL				14
+#define LPDDR2_MANID_NUMONYX				254
+#define LPDDR2_MANID_MICRON				255
+
+#define LPDDR2_TYPE_S4					0
+#define LPDDR2_TYPE_S2					1
+#define LPDDR2_TYPE_NVM					2
+
 /* Structure for DDR addressing info from the JEDEC spec */
 struct lpddr2_addressing {
 	u32 num_banks;
···
 extern const struct lpddr2_timings
 	lpddr2_jedec_timings[NUM_DDR_TIMING_TABLE_ENTRIES];
 extern const struct lpddr2_min_tck lpddr2_jedec_min_tck;
+
+/* Structure of MR8 */
+union lpddr2_basic_config4 {
+	u32 value;
+
+	struct {
+		unsigned int arch_type : 2;
+		unsigned int density : 4;
+		unsigned int io_width : 2;
+	} __packed;
+};
+
+/*
+ * Structure for information about LPDDR2 chip. All parameters are
+ * matching raw values of standard mode register bitfields or set to
+ * -ENOENT if info unavailable.
+ */
+struct lpddr2_info {
+	int arch_type;
+	int density;
+	int io_width;
+	int manufacturer_id;
+	int revision_id1;
+	int revision_id2;
+};
+
+const char *lpddr2_jedec_manufacturer(unsigned int manufacturer_id);
 
 /*
  * Structure for timings for LPDDR3 based on LPDDR2 plus additional fields.

drivers/memory/jedec_ddr_data.c

···
 	.tFAW		= 8
 };
 EXPORT_SYMBOL_GPL(lpddr2_jedec_min_tck);
+
+const char *lpddr2_jedec_manufacturer(unsigned int manufacturer_id)
+{
+	switch (manufacturer_id) {
+	case LPDDR2_MANID_SAMSUNG:
+		return "Samsung";
+	case LPDDR2_MANID_QIMONDA:
+		return "Qimonda";
+	case LPDDR2_MANID_ELPIDA:
+		return "Elpida";
+	case LPDDR2_MANID_ETRON:
+		return "Etron";
+	case LPDDR2_MANID_NANYA:
+		return "Nanya";
+	case LPDDR2_MANID_HYNIX:
+		return "Hynix";
+	case LPDDR2_MANID_MOSEL:
+		return "Mosel";
+	case LPDDR2_MANID_WINBOND:
+		return "Winbond";
+	case LPDDR2_MANID_ESMT:
+		return "ESMT";
+	case LPDDR2_MANID_SPANSION:
+		return "Spansion";
+	case LPDDR2_MANID_SST:
+		return "SST";
+	case LPDDR2_MANID_ZMOS:
+		return "ZMOS";
+	case LPDDR2_MANID_INTEL:
+		return "Intel";
+	case LPDDR2_MANID_NUMONYX:
+		return "Numonyx";
+	case LPDDR2_MANID_MICRON:
+		return "Micron";
+	default:
+		break;
+	}
+
+	return "invalid";
+}
+EXPORT_SYMBOL_GPL(lpddr2_jedec_manufacturer);

drivers/memory/of_memory.c

···
 	return NULL;
 }
 EXPORT_SYMBOL(of_lpddr3_get_ddr_timings);
+
+/**
+ * of_lpddr2_get_info() - extracts information about the lpddr2 chip.
+ * @np: Pointer to device tree node containing lpddr2 info
+ * @dev: Device requesting info
+ *
+ * Populates lpddr2_info structure by extracting data from device
+ * tree node. Returns pointer to populated structure. If error
+ * happened while populating, returns NULL. If property is missing
+ * in a device-tree, then the corresponding value is set to -ENOENT.
+ */
+const struct lpddr2_info
+*of_lpddr2_get_info(struct device_node *np, struct device *dev)
+{
+	struct lpddr2_info *ret_info, info = {};
+	struct property *prop;
+	const char *cp;
+	int err;
+
+	err = of_property_read_u32(np, "revision-id1", &info.revision_id1);
+	if (err)
+		info.revision_id1 = -ENOENT;
+
+	err = of_property_read_u32(np, "revision-id2", &info.revision_id2);
+	if (err)
+		info.revision_id2 = -ENOENT;
+
+	err = of_property_read_u32(np, "io-width", &info.io_width);
+	if (err)
+		return NULL;
+
+	info.io_width = 32 / info.io_width - 1;
+
+	err = of_property_read_u32(np, "density", &info.density);
+	if (err)
+		return NULL;
+
+	info.density = ffs(info.density) - 7;
+
+	if (of_device_is_compatible(np, "jedec,lpddr2-s4"))
+		info.arch_type = LPDDR2_TYPE_S4;
+	else if (of_device_is_compatible(np, "jedec,lpddr2-s2"))
+		info.arch_type = LPDDR2_TYPE_S2;
+	else if (of_device_is_compatible(np, "jedec,lpddr2-nvm"))
+		info.arch_type = LPDDR2_TYPE_NVM;
+	else
+		return NULL;
+
+	prop = of_find_property(np, "compatible", NULL);
+	for (cp = of_prop_next_string(prop, NULL); cp;
+	     cp = of_prop_next_string(prop, cp)) {
+
+#define OF_LPDDR2_VENDOR_CMP(compat, ID) \
+		if (!of_compat_cmp(cp, compat ",", strlen(compat ","))) { \
+			info.manufacturer_id = LPDDR2_MANID_##ID; \
+			break; \
+		}
+
+		OF_LPDDR2_VENDOR_CMP("samsung", SAMSUNG)
+		OF_LPDDR2_VENDOR_CMP("qimonda", QIMONDA)
+		OF_LPDDR2_VENDOR_CMP("elpida", ELPIDA)
+		OF_LPDDR2_VENDOR_CMP("etron", ETRON)
+		OF_LPDDR2_VENDOR_CMP("nanya", NANYA)
+		OF_LPDDR2_VENDOR_CMP("hynix", HYNIX)
+		OF_LPDDR2_VENDOR_CMP("mosel", MOSEL)
+		OF_LPDDR2_VENDOR_CMP("winbond", WINBOND)
+		OF_LPDDR2_VENDOR_CMP("esmt", ESMT)
+		OF_LPDDR2_VENDOR_CMP("spansion", SPANSION)
+		OF_LPDDR2_VENDOR_CMP("sst", SST)
+		OF_LPDDR2_VENDOR_CMP("zmos", ZMOS)
+		OF_LPDDR2_VENDOR_CMP("intel", INTEL)
+		OF_LPDDR2_VENDOR_CMP("numonyx", NUMONYX)
+		OF_LPDDR2_VENDOR_CMP("micron", MICRON)
+
+#undef OF_LPDDR2_VENDOR_CMP
+	}
+
+	if (!info.manufacturer_id)
+		info.manufacturer_id = -ENOENT;
+
+	ret_info = devm_kzalloc(dev, sizeof(*ret_info), GFP_KERNEL);
+	if (ret_info)
+		*ret_info = info;
+
+	return ret_info;
+}
+EXPORT_SYMBOL(of_lpddr2_get_info);

drivers/memory/of_memory.h

···
 const struct lpddr3_timings *
 of_lpddr3_get_ddr_timings(struct device_node *np_ddr,
 			  struct device *dev, u32 device_type, u32 *nr_frequencies);
+
+const struct lpddr2_info *of_lpddr2_get_info(struct device_node *np,
+					     struct device *dev);
 #else
 static inline const struct lpddr2_min_tck
 	*of_get_min_tck(struct device_node *np, struct device *dev)
···
 static inline const struct lpddr3_timings
 	*of_lpddr3_get_ddr_timings(struct device_node *np_ddr,
 	struct device *dev, u32 device_type, u32 *nr_frequencies)
+{
+	return NULL;
+}
+
+static inline const struct lpddr2_info
+	*of_lpddr2_get_info(struct device_node *np, struct device *dev)
 {
 	return NULL;
 }

drivers/memory/tegra/Kconfig

···
 	depends on ARCH_TEGRA_2x_SOC || COMPILE_TEST
 	select DEVFREQ_GOV_SIMPLE_ONDEMAND
 	select PM_DEVFREQ
+	select DDR
 	help
 	  This driver is for the External Memory Controller (EMC) found on
 	  Tegra20 chips. The EMC controls the external DRAM on the board.

drivers/memory/tegra/tegra20-emc.c

···
  * Author: Dmitry Osipenko <[e-mail]>
  */
 
+#include <linux/bitfield.h>
 #include <linux/clk.h>
 #include <linux/clk/tegra.h>
 #include <linux/debugfs.h>
···
 #include <soc/tegra/common.h>
 #include <soc/tegra/fuse.h>
 
+#include "../jedec_ddr.h"
+#include "../of_memory.h"
+
 #include "mc.h"
 
 #define EMC_INTSTATUS				0x000
 #define EMC_INTMASK				0x004
 #define EMC_DBG					0x008
+#define EMC_ADR_CFG_0				0x010
 #define EMC_TIMING_CONTROL			0x028
 #define EMC_RC					0x02c
 #define EMC_RFC					0x030
···
 #define EMC_QUSE_EXTRA				0x0ac
 #define EMC_ODT_WRITE				0x0b0
 #define EMC_ODT_READ				0x0b4
+#define EMC_MRR					0x0ec
 #define EMC_FBIO_CFG5				0x104
 #define EMC_FBIO_CFG6				0x114
 #define EMC_STAT_CONTROL			0x160
···
 
 #define EMC_REFRESH_OVERFLOW_INT		BIT(3)
 #define EMC_CLKCHANGE_COMPLETE_INT		BIT(4)
+#define EMC_MRR_DIVLD_INT			BIT(5)
 
 #define EMC_DBG_READ_MUX_ASSEMBLY		BIT(0)
 #define EMC_DBG_WRITE_MUX_ACTIVE		BIT(1)
···
 #define EMC_DBG_CFG_PRIORITY			BIT(24)
 
 #define EMC_FBIO_CFG5_DRAM_WIDTH_X16		BIT(4)
+#define EMC_FBIO_CFG5_DRAM_TYPE			GENMASK(1, 0)
+
+#define EMC_MRR_DEV_SELECTN			GENMASK(31, 30)
+#define EMC_MRR_MRR_MA				GENMASK(23, 16)
+#define EMC_MRR_MRR_DATA			GENMASK(15, 0)
+
+#define EMC_ADR_CFG_0_EMEM_NUMDEV		GENMASK(25, 24)
 
 #define EMC_PWR_GATHER_CLEAR			(1 << 8)
 #define EMC_PWR_GATHER_DISABLE			(2 << 8)
 #define EMC_PWR_GATHER_ENABLE			(3 << 8)
+
+enum emc_dram_type {
+	DRAM_TYPE_RESERVED,
+	DRAM_TYPE_DDR1,
+	DRAM_TYPE_LPDDR2,
+	DRAM_TYPE_DDR2,
+};
 
 static const u16 emc_timing_registers[] = {
 	EMC_RC,
···
 	struct mutex rate_lock;
 
 	struct devfreq_simple_ondemand_data ondemand_data;
+
+	/* memory chip identity information */
+	union lpddr2_basic_config4 basic_conf4;
+	unsigned int manufacturer_id;
+	unsigned int revision_id1;
+	unsigned int revision_id2;
+
+	bool mrr_error;
 };
 
 static irqreturn_t tegra_emc_isr(int irq, void *data)
···
 	if (!emc->timings)
 		return -ENOMEM;
 
-	emc->num_timings = child_count;
 	timing = emc->timings;
 
 	for_each_child_of_node(node, child) {
+		if (of_node_name_eq(child, "lpddr2"))
+			continue;
+
 		err = load_one_timing_from_dt(emc, timing++, child);
 		if (err) {
 			of_node_put(child);
 			return err;
 		}
+
+		emc->num_timings++;
 	}
 
 	sort(emc->timings, emc->num_timings, sizeof(*timing), cmp_timings,
···
 }
 
 static struct device_node *
-tegra_emc_find_node_by_ram_code(struct device *dev)
+tegra_emc_find_node_by_ram_code(struct tegra_emc *emc)
 {
+	struct device *dev = emc->dev;
 	struct device_node *np;
 	u32 value, ram_code;
 	int err;
+
+	if (emc->mrr_error) {
+		dev_warn(dev, "memory timings skipped due to MRR error\n");
+		return NULL;
+	}
 
 	if (of_get_child_count(dev->of_node) == 0) {
 		dev_info_once(dev, "device-tree doesn't have memory timings\n");
···
 	     np = of_find_node_by_name(np, "emc-tables")) {
 		err = of_property_read_u32(np, "nvidia,ram-code", &value);
 		if (err || value != ram_code) {
-			of_node_put(np);
-			continue;
+			struct device_node *lpddr2_np;
+			bool cfg_mismatches = false;
+
+			lpddr2_np = of_find_node_by_name(np, "lpddr2");
+			if (lpddr2_np) {
+				const struct lpddr2_info *info;
+
+				info = of_lpddr2_get_info(lpddr2_np, dev);
+				if (info) {
+					if (info->manufacturer_id >= 0 &&
+					    info->manufacturer_id != emc->manufacturer_id)
+						cfg_mismatches = true;
+
+					if (info->revision_id1 >= 0 &&
+					    info->revision_id1 != emc->revision_id1)
+						cfg_mismatches = true;
+
+					if (info->revision_id2 >= 0 &&
+					    info->revision_id2 != emc->revision_id2)
+						cfg_mismatches = true;
+
+					if (info->density != emc->basic_conf4.density)
+						cfg_mismatches = true;
+
+					if (info->io_width != emc->basic_conf4.io_width)
+						cfg_mismatches = true;
+
+					if (info->arch_type != emc->basic_conf4.arch_type)
+						cfg_mismatches = true;
+				} else {
+					dev_err(dev, "failed to parse %pOF\n", lpddr2_np);
+					cfg_mismatches = true;
+				}
+
+				of_node_put(lpddr2_np);
+			} else {
+				cfg_mismatches = true;
+			}
+
+			if (cfg_mismatches) {
+				of_node_put(np);
+				continue;
+			}
 		}
 
 		return np;
···
 	return NULL;
 }
 
+static int emc_read_lpddr_mode_register(struct tegra_emc *emc,
+					unsigned int emem_dev,
+					unsigned int register_addr,
+					unsigned int *register_data)
+{
+	u32 memory_dev = emem_dev + 1;
+	u32 val, mr_mask = 0xff;
+	int err;
+
+	/* clear data-valid interrupt status */
+	writel_relaxed(EMC_MRR_DIVLD_INT, emc->regs + EMC_INTSTATUS);
+
+	/* issue mode register read request */
+	val  = FIELD_PREP(EMC_MRR_DEV_SELECTN, memory_dev);
+	val |= FIELD_PREP(EMC_MRR_MRR_MA, register_addr);
+
+	writel_relaxed(val, emc->regs + EMC_MRR);
+
+	/* wait for the LPDDR2 data-valid interrupt */
+	err = readl_relaxed_poll_timeout_atomic(emc->regs + EMC_INTSTATUS, val,
+						val & EMC_MRR_DIVLD_INT,
+						1, 100);
+	if (err) {
+		dev_err(emc->dev, "mode register %u read failed: %d\n",
+			register_addr, err);
+		emc->mrr_error = true;
+		return err;
+	}
+
+	/* read out mode register data */
+	val = readl_relaxed(emc->regs + EMC_MRR);
+	*register_data = FIELD_GET(EMC_MRR_MRR_DATA, val) & mr_mask;
+
+	return 0;
+}
+
+static void emc_read_lpddr_sdram_info(struct tegra_emc *emc,
+				      unsigned int emem_dev,
+				      bool print_out)
+{
+	/* these registers are standard for all LPDDR JEDEC memory chips */
+	emc_read_lpddr_mode_register(emc, emem_dev, 5, &emc->manufacturer_id);
+	emc_read_lpddr_mode_register(emc, emem_dev, 6, &emc->revision_id1);
+	emc_read_lpddr_mode_register(emc, emem_dev, 7, &emc->revision_id2);
+	emc_read_lpddr_mode_register(emc, emem_dev, 8, &emc->basic_conf4.value);
+
+	if (!print_out)
+		return;
+
+	dev_info(emc->dev, "SDRAM[dev%u]: manufacturer: 0x%x (%s) rev1: 0x%x rev2: 0x%x prefetch: S%u density: %uMbit iowidth: %ubit\n",
+		 emem_dev, emc->manufacturer_id,
+		 lpddr2_jedec_manufacturer(emc->manufacturer_id),
+		 emc->revision_id1, emc->revision_id2,
+		 4 >> emc->basic_conf4.arch_type,
+		 64 << emc->basic_conf4.density,
+		 32 >> emc->basic_conf4.io_width);
+}
+
 static int emc_setup_hw(struct tegra_emc *emc)
 {
+	u32 emc_cfg, emc_dbg, emc_fbio, emc_adr_cfg;
 	u32 intmask = EMC_REFRESH_OVERFLOW_INT;
-	u32 emc_cfg, emc_dbg, emc_fbio;
+	static bool print_sdram_info_once;
+	enum emc_dram_type dram_type;
+	const char *dram_type_str;
+	unsigned int emem_numdev;
 
 	emc_cfg = readl_relaxed(emc->regs + EMC_CFG_2);
 
···
 	else
 		emc->dram_bus_width = 32;
 
-	dev_info_once(emc->dev, "%ubit DRAM bus\n", emc->dram_bus_width);
+	dram_type = FIELD_GET(EMC_FBIO_CFG5_DRAM_TYPE, emc_fbio);
+
+	switch (dram_type) {
+	case DRAM_TYPE_RESERVED:
+		dram_type_str = "INVALID";
+		break;
+	case DRAM_TYPE_DDR1:
+		dram_type_str = "DDR1";
+		break;
+	case DRAM_TYPE_LPDDR2:
+		dram_type_str = "LPDDR2";
+		break;
+	case DRAM_TYPE_DDR2:
+		dram_type_str = "DDR2";
+		break;
+	}
+
+	emc_adr_cfg = readl_relaxed(emc->regs + EMC_ADR_CFG_0);
+	emem_numdev = FIELD_GET(EMC_ADR_CFG_0_EMEM_NUMDEV, emc_adr_cfg) + 1;
+
+	dev_info_once(emc->dev, "%ubit DRAM bus, %u %s %s attached\n",
+		      emc->dram_bus_width, emem_numdev, dram_type_str,
+		      emem_numdev == 2 ? "devices" : "device");
+
+	if (dram_type == DRAM_TYPE_LPDDR2) {
+		while (emem_numdev--)
+			emc_read_lpddr_sdram_info(emc, emem_numdev,
+						  !print_sdram_info_once);
+		print_sdram_info_once = true;
+	}
 
 	return 0;
 }
···
 	emc->clk_nb.notifier_call = tegra_emc_clk_change_notify;
 	emc->dev = &pdev->dev;
 
-	np = tegra_emc_find_node_by_ram_code(&pdev->dev);
-	if (np) {
-		err = tegra_emc_load_timings_from_dt(emc, np);
-		of_node_put(np);
-		if (err)
-			return err;
-	}
-
 	emc->regs = devm_platform_ioremap_resource(pdev, 0);
 	if (IS_ERR(emc->regs))
 		return PTR_ERR(emc->regs);
···
 	err = emc_setup_hw(emc);
 	if (err)
 		return err;
+
+	np = tegra_emc_find_node_by_ram_code(emc);
+	if (np) {
+		err = tegra_emc_load_timings_from_dt(emc, np);
+		of_node_put(np);
+		if (err)
+			return err;
+	}
 
 	err = devm_request_irq(&pdev->dev, irq, tegra_emc_isr, 0,
 			       dev_name(&pdev->dev), emc);
···
 
 MODULE_AUTHOR("Dmitry Osipenko <[e-mail]>");
 MODULE_DESCRIPTION("NVIDIA Tegra20 EMC driver");
+MODULE_SOFTDEP("pre: governor_simpleondemand");
 MODULE_LICENSE("GPL v2");