diff --git a/Documentation/devicetree/bindings/net/brcm,amac.txt b/Documentation/devicetree/bindings/net/brcm,amac.txt
index 2fefa1a44afd..ad16c1f481f7 100644
--- a/Documentation/devicetree/bindings/net/brcm,amac.txt
+++ b/Documentation/devicetree/bindings/net/brcm,amac.txt
@@ -11,6 +11,7 @@ Required properties:
  - reg-names:	Names of the registers.
 		"amac_base":	Address and length of the GMAC registers
 		"idm_base":	Address and length of the GMAC IDM registers
+				(required for NSP and Northstar2)
 		"nicpm_base":	Address and length of the NIC Port Manager
 				registers (required for Northstar2)
  - interrupts:	Interrupt number
diff --git a/drivers/net/ethernet/broadcom/bgmac-platform.c b/drivers/net/ethernet/broadcom/bgmac-platform.c
index 73aca97a96bc..d937083db9a4 100644
--- a/drivers/net/ethernet/broadcom/bgmac-platform.c
+++ b/drivers/net/ethernet/broadcom/bgmac-platform.c
@@ -50,11 +50,14 @@ static u32 platform_bgmac_idm_read(struct bgmac *bgmac, u16 offset)
 
 static void platform_bgmac_idm_write(struct bgmac *bgmac, u16 offset, u32 value)
 {
-	return writel(value, bgmac->plat.idm_base + offset);
+	writel(value, bgmac->plat.idm_base + offset);
 }
 
 static bool platform_bgmac_clk_enabled(struct bgmac *bgmac)
 {
+	if (!bgmac->plat.idm_base)
+		return true;
+
 	if ((bgmac_idm_read(bgmac, BCMA_IOCTL) & BGMAC_CLK_EN) != BGMAC_CLK_EN)
 		return false;
 	if (bgmac_idm_read(bgmac, BCMA_RESET_CTL) & BCMA_RESET_CTL_RESET)
@@ -66,6 +69,9 @@ static void platform_bgmac_clk_enable(struct bgmac *bgmac, u32 flags)
 {
 	u32 val;
 
+	if (!bgmac->plat.idm_base)
+		return;
+
 	/* The Reset Control register only contains a single bit to show if the
 	 * controller is currently in reset.  Do a sanity check here, just in
 	 * case the bootloader happened to leave the device in reset.
@@ -180,6 +186,7 @@ static int bgmac_probe(struct platform_device *pdev)
 	bgmac->feature_flags |= BGMAC_FEAT_CMDCFG_SR_REV4;
 	bgmac->feature_flags |= BGMAC_FEAT_TX_MASK_SETUP;
 	bgmac->feature_flags |= BGMAC_FEAT_RX_MASK_SETUP;
+	bgmac->feature_flags |= BGMAC_FEAT_IDM_MASK;
 
 	bgmac->dev = &pdev->dev;
 	bgmac->dma_dev = &pdev->dev;
@@ -207,15 +214,13 @@ static int bgmac_probe(struct platform_device *pdev)
 		return PTR_ERR(bgmac->plat.base);
 
 	regs = platform_get_resource_byname(pdev, IORESOURCE_MEM, "idm_base");
-	if (!regs) {
-		dev_err(&pdev->dev, "Unable to obtain idm resource\n");
-		return -EINVAL;
+	if (regs) {
+		bgmac->plat.idm_base = devm_ioremap_resource(&pdev->dev, regs);
+		if (IS_ERR(bgmac->plat.idm_base))
+			return PTR_ERR(bgmac->plat.idm_base);
+		bgmac->feature_flags &= ~BGMAC_FEAT_IDM_MASK;
 	}
 
-	bgmac->plat.idm_base = devm_ioremap_resource(&pdev->dev, regs);
-	if (IS_ERR(bgmac->plat.idm_base))
-		return PTR_ERR(bgmac->plat.idm_base);
-
 	regs = platform_get_resource_byname(pdev, IORESOURCE_MEM, "nicpm_base");
 	if (regs) {
 		bgmac->plat.nicpm_base = devm_ioremap_resource(&pdev->dev,
diff --git a/drivers/net/ethernet/broadcom/bgmac.c b/drivers/net/ethernet/broadcom/bgmac.c
index ba4d2e145bb9..48d672b204a4 100644
--- a/drivers/net/ethernet/broadcom/bgmac.c
+++ b/drivers/net/ethernet/broadcom/bgmac.c
@@ -622,9 +622,11 @@ static int bgmac_dma_alloc(struct bgmac *bgmac)
 	BUILD_BUG_ON(BGMAC_MAX_TX_RINGS > ARRAY_SIZE(ring_base));
 	BUILD_BUG_ON(BGMAC_MAX_RX_RINGS > ARRAY_SIZE(ring_base));
 
-	if (!(bgmac_idm_read(bgmac, BCMA_IOST) & BCMA_IOST_DMA64)) {
-		dev_err(bgmac->dev, "Core does not report 64-bit DMA\n");
-		return -ENOTSUPP;
+	if (!(bgmac->feature_flags & BGMAC_FEAT_IDM_MASK)) {
+		if (!(bgmac_idm_read(bgmac, BCMA_IOST) & BCMA_IOST_DMA64)) {
+			dev_err(bgmac->dev, "Core does not report 64-bit DMA\n");
+			return -ENOTSUPP;
+		}
 	}
 
 	for (i = 0; i < BGMAC_MAX_TX_RINGS; i++) {
@@ -855,9 +857,11 @@ static void bgmac_mac_speed(struct bgmac *bgmac)
 static void bgmac_miiconfig(struct bgmac *bgmac)
 {
 	if (bgmac->feature_flags & BGMAC_FEAT_FORCE_SPEED_2500) {
-		bgmac_idm_write(bgmac, BCMA_IOCTL,
-				bgmac_idm_read(bgmac, BCMA_IOCTL) | 0x40 |
-				BGMAC_BCMA_IOCTL_SW_CLKEN);
+		if (!(bgmac->feature_flags & BGMAC_FEAT_IDM_MASK)) {
+			bgmac_idm_write(bgmac, BCMA_IOCTL,
+					bgmac_idm_read(bgmac, BCMA_IOCTL) |
+					0x40 | BGMAC_BCMA_IOCTL_SW_CLKEN);
+		}
 		bgmac->mac_speed = SPEED_2500;
 		bgmac->mac_duplex = DUPLEX_FULL;
 		bgmac_mac_speed(bgmac);
@@ -874,11 +878,36 @@ static void bgmac_miiconfig(struct bgmac *bgmac)
 	}
 }
 
+static void bgmac_chip_reset_idm_config(struct bgmac *bgmac)
+{
+	u32 iost;
+
+	iost = bgmac_idm_read(bgmac, BCMA_IOST);
+	if (bgmac->feature_flags & BGMAC_FEAT_IOST_ATTACHED)
+		iost &= ~BGMAC_BCMA_IOST_ATTACHED;
+
+	/* 3GMAC: for BCM4707 & BCM47094, only do core reset at bgmac_probe() */
+	if (!(bgmac->feature_flags & BGMAC_FEAT_NO_RESET)) {
+		u32 flags = 0;
+
+		if (iost & BGMAC_BCMA_IOST_ATTACHED) {
+			flags = BGMAC_BCMA_IOCTL_SW_CLKEN;
+			if (!bgmac->has_robosw)
+				flags |= BGMAC_BCMA_IOCTL_SW_RESET;
+		}
+		bgmac_clk_enable(bgmac, flags);
+	}
+
+	if (iost & BGMAC_BCMA_IOST_ATTACHED && !bgmac->has_robosw)
+		bgmac_idm_write(bgmac, BCMA_IOCTL,
+				bgmac_idm_read(bgmac, BCMA_IOCTL) &
+				~BGMAC_BCMA_IOCTL_SW_RESET);
+}
+
 /* http://bcm-v4.sipsolutions.net/mac-gbit/gmac/chipreset */
 static void bgmac_chip_reset(struct bgmac *bgmac)
 {
 	u32 cmdcfg_sr;
-	u32 iost;
 	int i;
 
 	if (bgmac_clk_enabled(bgmac)) {
@@ -899,20 +928,8 @@ static void bgmac_chip_reset(struct bgmac *bgmac)
 		/* TODO: Clear software multicast filter list */
 	}
 
-	iost = bgmac_idm_read(bgmac, BCMA_IOST);
-	if (bgmac->feature_flags & BGMAC_FEAT_IOST_ATTACHED)
-		iost &= ~BGMAC_BCMA_IOST_ATTACHED;
-
-	/* 3GMAC: for BCM4707 & BCM47094, only do core reset at bgmac_probe() */
-	if (!(bgmac->feature_flags & BGMAC_FEAT_NO_RESET)) {
-		u32 flags = 0;
-		if (iost & BGMAC_BCMA_IOST_ATTACHED) {
-			flags = BGMAC_BCMA_IOCTL_SW_CLKEN;
-			if (!bgmac->has_robosw)
-				flags |= BGMAC_BCMA_IOCTL_SW_RESET;
-		}
-		bgmac_clk_enable(bgmac, flags);
-	}
+	if (!(bgmac->feature_flags & BGMAC_FEAT_IDM_MASK))
+		bgmac_chip_reset_idm_config(bgmac);
 
 	/* Request Misc PLL for corerev > 2 */
 	if (bgmac->feature_flags & BGMAC_FEAT_MISC_PLL_REQ) {
@@ -970,11 +987,6 @@ static void bgmac_chip_reset(struct bgmac *bgmac)
 				      BGMAC_CHIPCTL_7_IF_TYPE_RGMII);
 	}
 
-	if (iost & BGMAC_BCMA_IOST_ATTACHED && !bgmac->has_robosw)
-		bgmac_idm_write(bgmac, BCMA_IOCTL,
-				bgmac_idm_read(bgmac, BCMA_IOCTL) &
-				~BGMAC_BCMA_IOCTL_SW_RESET);
-
 	/* http://bcm-v4.sipsolutions.net/mac-gbit/gmac/gmac_reset
 	 * Specs don't say about using BGMAC_CMDCFG_SR, but in this routine
 	 * BGMAC_CMDCFG is read _after_ putting chip in a reset. So it has to
@@ -1497,8 +1509,10 @@ int bgmac_enet_probe(struct bgmac *bgmac)
 	bgmac_clk_enable(bgmac, 0);
 
 	/* This seems to be fixing IRQ by assigning OOB #6 to the core */
-	if (bgmac->feature_flags & BGMAC_FEAT_IRQ_ID_OOB_6)
-		bgmac_idm_write(bgmac, BCMA_OOB_SEL_OUT_A30, 0x86);
+	if (!(bgmac->feature_flags & BGMAC_FEAT_IDM_MASK)) {
+		if (bgmac->feature_flags & BGMAC_FEAT_IRQ_ID_OOB_6)
+			bgmac_idm_write(bgmac, BCMA_OOB_SEL_OUT_A30, 0x86);
+	}
 
 	bgmac_chip_reset(bgmac);
 
diff --git a/drivers/net/ethernet/broadcom/bgmac.h b/drivers/net/ethernet/broadcom/bgmac.h
index c1818766c501..443d57b10264 100644
--- a/drivers/net/ethernet/broadcom/bgmac.h
+++ b/drivers/net/ethernet/broadcom/bgmac.h
@@ -425,6 +425,7 @@
 #define BGMAC_FEAT_CC4_IF_SW_TYPE	BIT(17)
 #define BGMAC_FEAT_CC4_IF_SW_TYPE_RGMII	BIT(18)
 #define BGMAC_FEAT_CC7_IF_TYPE_RGMII	BIT(19)
+#define BGMAC_FEAT_IDM_MASK		BIT(20)
 
 struct bgmac_slot_info {
 	union {