[v4, PATCH 0/2] add Ethernet driver support for mt2712

[v4, PATCH 0/2] add Ethernet driver support for mt2712

[Biao Huang]

Changes in v4:
modifications according to comments from Rob and Sean:
1. call clk_bulk api to simplify clk settings.
2. add prefix for mediatek specified properties
3. evolution to a more general driver

[v4, PATCH 1/2] net:stmmac: dwmac-mediatek: add support for mt2712

[Biao Huang]

Add Ethernet support for MediaTek SoCs from the mt2712 family

Signed-off-by: Biao Huang <biao.huang@mediatek.com>
---
 drivers/net/ethernet/stmicro/stmmac/Kconfig        |    8 +
 drivers/net/ethernet/stmicro/stmmac/Makefile       |    1 +
 .../net/ethernet/stmicro/stmmac/dwmac-mediatek.c   |  361 ++++++++++++++++++++
 3 files changed, 370 insertions(+)
 create mode 100644 drivers/net/ethernet/stmicro/stmmac/dwmac-mediatek.c

diff --git a/drivers/net/ethernet/stmicro/stmmac/Kconfig b/drivers/net/ethernet/stmicro/stmmac/Kconfig
index 324049e..6209cc1 100644
--- a/drivers/net/ethernet/stmicro/stmmac/Kconfig
+++ b/drivers/net/ethernet/stmicro/stmmac/Kconfig
@@ -75,6 +75,14 @@ config DWMAC_LPC18XX
 	---help---
 	  Support for NXP LPC18xx/43xx DWMAC Ethernet.
 
+config DWMAC_MEDIATEK
+	tristate "MediaTek MT27xx GMAC support"
+	depends on OF && (ARCH_MEDIATEK || COMPILE_TEST)
+	help
+	  Support for MediaTek GMAC Ethernet controller.
+
+	  This selects the MT2712 SoC support for the stmmac driver.
+
 config DWMAC_MESON
 	tristate "Amlogic Meson dwmac support"
 	default ARCH_MESON
diff --git a/drivers/net/ethernet/stmicro/stmmac/Makefile b/drivers/net/ethernet/stmicro/stmmac/Makefile
index 99967a8..bf09701 100644
--- a/drivers/net/ethernet/stmicro/stmmac/Makefile
+++ b/drivers/net/ethernet/stmicro/stmmac/Makefile
@@ -13,6 +13,7 @@ obj-$(CONFIG_STMMAC_PLATFORM)	+= stmmac-platform.o
 obj-$(CONFIG_DWMAC_ANARION)	+= dwmac-anarion.o
 obj-$(CONFIG_DWMAC_IPQ806X)	+= dwmac-ipq806x.o
 obj-$(CONFIG_DWMAC_LPC18XX)	+= dwmac-lpc18xx.o
+obj-$(CONFIG_DWMAC_MEDIATEK)	+= dwmac-mediatek.o
 obj-$(CONFIG_DWMAC_MESON)	+= dwmac-meson.o dwmac-meson8b.o
 obj-$(CONFIG_DWMAC_OXNAS)	+= dwmac-oxnas.o
 obj-$(CONFIG_DWMAC_ROCKCHIP)	+= dwmac-rk.o
diff --git a/drivers/net/ethernet/stmicro/stmmac/dwmac-mediatek.c b/drivers/net/ethernet/stmicro/stmmac/dwmac-mediatek.c
new file mode 100644
index 0000000..684b2f1
--- /dev/null
+++ b/drivers/net/ethernet/stmicro/stmmac/dwmac-mediatek.c
@@ -0,0 +1,361 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (c) 2018 MediaTek Inc.
+ */
+#include <linux/io.h>
+#include <linux/mfd/syscon.h>
+#include <linux/of.h>
+#include <linux/of_device.h>
+#include <linux/of_net.h>
+#include <linux/regmap.h>
+#include <linux/stmmac.h>
+
+#include "stmmac.h"
+#include "stmmac_platform.h"
+
+/* Peri Configuration register for mt2712 */
+#define PERI_ETH_PHY_INTF_SEL	0x418
+#define PHY_INTF_MII_GMII	0
+#define PHY_INTF_RGMII		1
+#define PHY_INTF_RMII		4
+#define RMII_CLK_SRC_RXC	BIT(4)
+#define RMII_CLK_SRC_INTERNAL	BIT(5)
+
+#define PERI_ETH_PHY_DLY	0x428
+#define PHY_DLY_GTXC_INV	BIT(6)
+#define PHY_DLY_GTXC_ENABLE	BIT(5)
+#define PHY_DLY_GTXC_STAGES	GENMASK(4, 0)
+#define PHY_DLY_TXC_INV		BIT(20)
+#define PHY_DLY_TXC_ENABLE	BIT(19)
+#define PHY_DLY_TXC_STAGES	GENMASK(18, 14)
+#define PHY_DLY_TXC_SHIFT	14
+#define PHY_DLY_RXC_INV		BIT(13)
+#define PHY_DLY_RXC_ENABLE	BIT(12)
+#define PHY_DLY_RXC_STAGES	GENMASK(11, 7)
+#define PHY_DLY_RXC_SHIFT	7
+
+#define PERI_ETH_DLY_FINE	0x800
+#define ETH_RMII_DLY_TX_INV	BIT(2)
+#define ETH_FINE_DLY_GTXC	BIT(1)
+#define ETH_FINE_DLY_RXC	BIT(0)
+
+struct mac_delay_struct {
+	u32 tx_delay;
+	u32 rx_delay;
+	u32 tx_inv;
+	u32 rx_inv;
+};
+
+struct mediatek_dwmac_plat_data {
+	const struct mediatek_dwmac_variant *variant;
+	struct mac_delay_struct mac_delay;
+	struct clk_bulk_data *clks;
+	struct device_node *np;
+	struct regmap *peri_regmap;
+	struct device *dev;
+	int fine_tune;
+	int phy_mode;
+	int rmii_rxc;
+};
+
+struct mediatek_dwmac_variant {
+	int (*dwmac_set_phy_interface)(struct mediatek_dwmac_plat_data *plat);
+	int (*dwmac_set_delay)(struct mediatek_dwmac_plat_data *plat);
+
+	/* clock ids to be requested */
+	const char * const *clk_list;
+	int num_clks;
+
+	u32 dma_bit_mask;
+	u32 rx_delay_max;
+	u32 tx_delay_max;
+};
+
+/* list of clocks required for mac */
+static const char * const mt2712_dwmac_clk_l[] = {
+	"axi", "apb", "mac_main", "ptp_ref"
+};
+
+static int mt2712_set_interface(struct mediatek_dwmac_plat_data *plat)
+{
+	int rmii_rxc = plat->rmii_rxc ? RMII_CLK_SRC_RXC : 0;
+	u32 intf_val = 0;
+
+	/* select phy interface in top control domain */
+	switch (plat->phy_mode) {
+	case PHY_INTERFACE_MODE_MII:
+		intf_val |= PHY_INTF_MII_GMII;
+		break;
+	case PHY_INTERFACE_MODE_RMII:
+		intf_val |= PHY_INTF_RMII;
+		intf_val |= rmii_rxc;
+		break;
+	case PHY_INTERFACE_MODE_RGMII:
+	case PHY_INTERFACE_MODE_RGMII_TXID:
+	case PHY_INTERFACE_MODE_RGMII_RXID:
+	case PHY_INTERFACE_MODE_RGMII_ID:
+		intf_val |= PHY_INTF_RGMII;
+		break;
+	default:
+		dev_err(plat->dev, "phy interface not supported\n");
+		return -EINVAL;
+	}
+
+	regmap_write(plat->peri_regmap, PERI_ETH_PHY_INTF_SEL, intf_val);
+
+	return 0;
+}
+
+static int mt2712_set_delay(struct mediatek_dwmac_plat_data *plat)
+{
+	struct mac_delay_struct *mac_delay = &plat->mac_delay;
+	u32 delay_val = 0;
+	u32 fine_val = 0;
+
+	switch (plat->phy_mode) {
+	case PHY_INTERFACE_MODE_MII:
+		delay_val |= mac_delay->tx_delay ? PHY_DLY_TXC_ENABLE : 0;
+		delay_val |= (mac_delay->tx_delay << PHY_DLY_TXC_SHIFT) &
+			     PHY_DLY_TXC_STAGES;
+		delay_val |= mac_delay->tx_inv ? PHY_DLY_TXC_INV : 0;
+		delay_val |= mac_delay->rx_delay ? PHY_DLY_RXC_ENABLE : 0;
+		delay_val |= (mac_delay->rx_delay << PHY_DLY_RXC_SHIFT) &
+			     PHY_DLY_RXC_STAGES;
+		delay_val |= mac_delay->rx_inv ? PHY_DLY_RXC_INV : 0;
+		break;
+	case PHY_INTERFACE_MODE_RMII:
+		if (plat->rmii_rxc) {
+			delay_val |= mac_delay->rx_delay ?
+				     PHY_DLY_RXC_ENABLE : 0;
+			delay_val |= (mac_delay->rx_delay <<
+				      PHY_DLY_RXC_SHIFT) & PHY_DLY_RXC_STAGES;
+			delay_val |= mac_delay->rx_inv ? PHY_DLY_RXC_INV : 0;
+			fine_val |= mac_delay->tx_inv ?
+				     ETH_RMII_DLY_TX_INV : 0;
+		} else {
+			delay_val |= mac_delay->rx_delay ?
+				     PHY_DLY_TXC_ENABLE : 0;
+			delay_val |= (mac_delay->rx_delay <<
+				     PHY_DLY_TXC_SHIFT) & PHY_DLY_TXC_STAGES;
+			delay_val |= mac_delay->rx_inv ? PHY_DLY_TXC_INV : 0;
+			fine_val |= mac_delay->tx_inv ?
+				     ETH_RMII_DLY_TX_INV : 0;
+		}
+		break;
+	case PHY_INTERFACE_MODE_RGMII:
+		fine_val = plat->fine_tune ?
+			    (ETH_FINE_DLY_GTXC | ETH_FINE_DLY_RXC) : 0;
+		delay_val |= mac_delay->tx_delay ? PHY_DLY_GTXC_ENABLE : 0;
+		delay_val |= mac_delay->tx_delay & PHY_DLY_GTXC_STAGES;
+		delay_val |= mac_delay->tx_inv ? PHY_DLY_GTXC_INV : 0;
+		delay_val |= mac_delay->rx_delay ? PHY_DLY_RXC_ENABLE : 0;
+		delay_val |= (mac_delay->rx_delay << PHY_DLY_RXC_SHIFT) &
+			     PHY_DLY_RXC_STAGES;
+		delay_val |= mac_delay->rx_inv ? PHY_DLY_RXC_INV : 0;
+		break;
+	case PHY_INTERFACE_MODE_RGMII_TXID:
+		fine_val = plat->fine_tune ? ETH_FINE_DLY_RXC : 0;
+		delay_val |= mac_delay->rx_delay ? PHY_DLY_RXC_ENABLE : 0;
+		delay_val |= (mac_delay->rx_delay << PHY_DLY_RXC_SHIFT) &
+			     PHY_DLY_RXC_STAGES;
+		delay_val |= mac_delay->rx_inv ? PHY_DLY_RXC_INV : 0;
+		break;
+	case PHY_INTERFACE_MODE_RGMII_RXID:
+		fine_val = plat->fine_tune ? ETH_FINE_DLY_GTXC : 0;
+		delay_val |= mac_delay->tx_delay ? PHY_DLY_GTXC_ENABLE : 0;
+		delay_val |= mac_delay->tx_delay & PHY_DLY_GTXC_STAGES;
+		delay_val |= mac_delay->tx_inv ? PHY_DLY_GTXC_INV : 0;
+		break;
+	case PHY_INTERFACE_MODE_RGMII_ID:
+		break;
+	default:
+		dev_err(plat->dev, "phy interface not supported\n");
+		return -EINVAL;
+	}
+	regmap_write(plat->peri_regmap, PERI_ETH_PHY_DLY, delay_val);
+	regmap_write(plat->peri_regmap, PERI_ETH_DLY_FINE, fine_val);
+
+	return 0;
+}
+
+static const struct mediatek_dwmac_variant mt2712_gmac_variant = {
+		.dwmac_set_phy_interface = mt2712_set_interface,
+		.dwmac_set_delay = mt2712_set_delay,
+		.clk_list = mt2712_dwmac_clk_l,
+		.num_clks = ARRAY_SIZE(mt2712_dwmac_clk_l),
+		.dma_bit_mask = 33,
+		.rx_delay_max = 32,
+		.tx_delay_max = 32,
+};
+
+static int mediatek_dwmac_config_dt(struct mediatek_dwmac_plat_data *plat)
+{
+	u32 tx_delay, rx_delay;
+
+	plat->peri_regmap = syscon_regmap_lookup_by_phandle(plat->np, "mediatek,pericfg");
+	if (IS_ERR(plat->peri_regmap)) {
+		dev_err(plat->dev, "Failed to get pericfg syscon\n");
+		return PTR_ERR(plat->peri_regmap);
+	}
+
+	plat->phy_mode = of_get_phy_mode(plat->np);
+	if (plat->phy_mode < 0) {
+		dev_err(plat->dev, "not find phy-mode\n");
+		return -EINVAL;
+	}
+
+	if (!of_property_read_u32(plat->np, "mediatek,tx-delay", &tx_delay)) {
+		if (tx_delay < plat->variant->tx_delay_max) {
+			plat->mac_delay.tx_delay = tx_delay;
+		} else {
+			dev_err(plat->dev, "Invalid TX clock delay: %d\n", tx_delay);
+			return -EINVAL;
+		}
+	}
+
+	if (!of_property_read_u32(plat->np, "mediatek,rx-delay", &rx_delay)) {
+		if (rx_delay < plat->variant->rx_delay_max) {
+			plat->mac_delay.rx_delay = rx_delay;
+		} else {
+			dev_err(plat->dev, "Invalid RX clock delay: %d\n", rx_delay);
+			return -EINVAL;
+		}
+	}
+
+	plat->mac_delay.tx_inv = of_property_read_bool(plat->np, "mediatek,txc-inverse");
+	plat->mac_delay.rx_inv = of_property_read_bool(plat->np, "mediatek,rxc-inverse");
+	plat->fine_tune = of_property_read_bool(plat->np, "mediatek,fine-tune");
+	plat->rmii_rxc = of_property_read_bool(plat->np, "mediatek,rmii-rxc");
+
+	return 0;
+}
+
+static int mediatek_dwmac_clk_init(struct mediatek_dwmac_plat_data *plat)
+{
+	const struct mediatek_dwmac_variant *variant = plat->variant;
+	int num = variant->num_clks;
+	int i;
+
+	plat->clks = devm_kcalloc(plat->dev, num, sizeof(*plat->clks), GFP_KERNEL);
+	if (!plat->clks)
+		return -ENOMEM;
+
+	for (i = 0; i < num; i++)
+		plat->clks[i].id = variant->clk_list[i];
+
+	return devm_clk_bulk_get(plat->dev, num, plat->clks);
+}
+
+static int mediatek_dwmac_init(struct platform_device *pdev, void *priv)
+{
+	struct mediatek_dwmac_plat_data *plat = priv;
+	const struct mediatek_dwmac_variant *variant = plat->variant;
+	int ret = 0;
+
+	/* Set the DMA mask, 4GB mode enabled */
+	dma_set_mask_and_coherent(plat->dev, variant->dma_bit_mask);
+
+	ret = variant->dwmac_set_phy_interface(plat);
+	if (ret) {
+		dev_err(plat->dev, "failed to set phy interface, err = %d\n", ret);
+		return ret;
+	} 
+
+	ret = variant->dwmac_set_delay(plat);
+	if (ret) {
+		dev_err(plat->dev, "failed to set delay value, err = %d\n", ret);
+		return ret;
+	}
+
+	ret = clk_bulk_prepare_enable(variant->num_clks, plat->clks);
+	if (ret) {
+		dev_err(plat->dev, "failed to enable clks, err = %d\n", ret);
+		return ret;
+	}
+
+	return 0;
+}
+
+static void mediatek_dwmac_exit(struct platform_device *pdev, void *priv)
+{
+	struct mediatek_dwmac_plat_data *plat = priv;
+	const struct mediatek_dwmac_variant *variant = plat->variant;
+
+	clk_bulk_disable_unprepare(variant->num_clks, plat->clks);
+}
+
+static int mediatek_dwmac_probe(struct platform_device *pdev)
+{
+	struct mediatek_dwmac_plat_data *priv_plat;
+	struct plat_stmmacenet_data *plat_dat;
+	struct stmmac_resources stmmac_res;
+	int ret = 0;
+
+	priv_plat = devm_kzalloc(&pdev->dev, sizeof(*priv_plat), GFP_KERNEL);
+	if (!priv_plat)
+		return -ENOMEM;
+
+	priv_plat->variant = of_device_get_match_data(&pdev->dev);
+	if (!priv_plat->variant) {
+		dev_err(&pdev->dev, "Missing dwmac-mediatek variant\n");
+		return -EINVAL;
+	}
+
+	priv_plat->dev = &pdev->dev;
+	priv_plat->np = pdev->dev.of_node;
+
+	ret = mediatek_dwmac_config_dt(priv_plat);
+	if (ret)
+		return ret;
+
+	ret = mediatek_dwmac_clk_init(priv_plat);
+	if (ret)
+		return ret;
+
+	ret = stmmac_get_platform_resources(pdev, &stmmac_res);
+	if (ret)
+		return ret;
+
+	plat_dat = stmmac_probe_config_dt(pdev, &stmmac_res.mac);
+	if (IS_ERR(plat_dat))
+		return PTR_ERR(plat_dat);
+
+	plat_dat->interface = priv_plat->phy_mode;
+	/* clk_csr_i = 250-300MHz & MDC = clk_csr_i/124 */
+	plat_dat->clk_csr = 5;
+	plat_dat->has_gmac4 = 1;
+	plat_dat->has_gmac = 0;
+	plat_dat->pmt = 0;
+	plat_dat->maxmtu = ETH_DATA_LEN;
+	plat_dat->bsp_priv = priv_plat;
+	plat_dat->init = mediatek_dwmac_init;
+	plat_dat->exit = mediatek_dwmac_exit;
+	mediatek_dwmac_init(pdev, priv_plat);
+
+	ret = stmmac_dvr_probe(&pdev->dev, plat_dat, &stmmac_res);
+	if (ret) {
+		stmmac_remove_config_dt(pdev, plat_dat);
+		return ret;
+	}
+
+	return 0;
+}
+
+static const struct of_device_id mediatek_dwmac_match[] = {
+	{ .compatible = "mediatek,mt2712-gmac",
+	  .data = &mt2712_gmac_variant },
+	{ }
+};
+
+MODULE_DEVICE_TABLE(of, mediatek_dwmac_match);
+
+static struct platform_driver mediatek_dwmac_driver = {
+	.probe  = mediatek_dwmac_probe,
+	.remove = stmmac_pltfr_remove,
+	.driver = {
+		.name           = "dwmac-mediatek",
+		.pm		= &stmmac_pltfr_pm_ops,
+		.of_match_table = mediatek_dwmac_match,
+	},
+};
+module_platform_driver(mediatek_dwmac_driver);
-- 
1.7.9.5

[v4, PATCH 2/2] dt-binding: mediatek-dwmac: add binding document for MediaTek MT2712 DWMAC

[Biao Huang]

The commit adds the device tree binding documentation for the MediaTek DWMAC
found on MediaTek MT2712.

Signed-off-by: Biao Huang <biao.huang@mediatek.com>
---
 .../devicetree/bindings/net/mediatek-dwmac.txt     |   78 ++++++++++++++++++++
 1 file changed, 78 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/net/mediatek-dwmac.txt

diff --git a/Documentation/devicetree/bindings/net/mediatek-dwmac.txt b/Documentation/devicetree/bindings/net/mediatek-dwmac.txt
new file mode 100644
index 0000000..0f8a915
--- /dev/null
+++ b/Documentation/devicetree/bindings/net/mediatek-dwmac.txt
@@ -0,0 +1,78 @@
+MediaTek DWMAC glue layer controller
+
+This file documents platform glue layer for stmmac.
+Please see stmmac.txt for the other unchanged properties.
+
+The device node has following properties.
+
+Required properties:
+- compatible:  Should be "mediatek,mt2712-gmac" for MT2712 SoC
+- reg:  Address and length of the register set for the device
+- interrupts:  Should contain the MAC interrupts
+- interrupt-names: Should contain a list of interrupt names corresponding to
+	the interrupts in the interrupts property, if available.
+	Should be "macirq" for the main MAC IRQ
+- clocks: Must contain a phandle for each entry in clock-names.
+- clock-names: The name of the clock listed in the clocks property. These are
+	"axi", "apb", "mac_main", "ptp_ref" for MT2712 SoC
+- mac-address: See ethernet.txt in the same directory
+- phy-mode: See ethernet.txt in the same directory
+
+Optional properties:
+- mediatek,tx-delay: TX clock delay macro value. Range is 0~31. Default is 0.
+	It should be defined for rgmii/rgmii-rxid/mii interface.
+- mediatek,rx-delay: RX clock delay macro value. Range is 0~31. Default is 0.
+	It should be defined for rgmii/rgmii-txid/mii/rmii interface.
+- mediatek,fine-tune: boolean property, if present indicates that fine delay
+	is selected for rgmii interface.
+	If present, tx-delay/rx-delay is 170+/-50ps per stage.
+	Else tx-delay/rx-delay of coarse delay macro is 0.55+/-0.2ns per stage.
+	This property do not apply to non-rgmii PHYs.
+	Only coarse-tune delay is supported for mii/rmii PHYs.
+- mediatek,rmii-rxc: boolean property, if present indicates that the rmii
+	reference clock, which is from external PHYs, is connected to RXC pin
+	on MT2712 SoC.
+	Otherwise, is connected to TXC pin.
+- mediatek,txc-inverse: boolean property, if present indicates that
+	1. tx clock will be inversed in mii/rgmii case,
+	2. tx clock inside MAC will be inversed relative to reference clock
+	   which is from external PHYs in rmii case, and it rarely happen.
+- mediatek,rxc-inverse: boolean property, if present indicates that
+	1. rx clock will be inversed in mii/rgmii case.
+	2. reference clock will be inversed when arrived at MAC in rmii case.
+- assigned-clocks: mac_main and ptp_ref clocks
+- assigned-clock-parents: parent clocks of the assigned clocks
+
+Example:
+	eth: ethernet@1101c000 {
+		compatible = "mediatek,mt2712-gmac";
+		reg = <0 0x1101c000 0 0x1300>;
+		interrupts = <GIC_SPI 237 IRQ_TYPE_LEVEL_LOW>;
+		interrupt-names = "macirq";
+		phy-mode ="rgmii-id";
+		mac-address = [00 55 7b b5 7d f7];
+		clock-names = "axi",
+			      "apb",
+			      "mac_main",
+			      "ptp_ref",
+			      "ptp_top";
+		clocks = <&pericfg CLK_PERI_GMAC>,
+			 <&pericfg CLK_PERI_GMAC_PCLK>,
+			 <&topckgen CLK_TOP_ETHER_125M_SEL>,
+			 <&topckgen CLK_TOP_ETHER_50M_SEL>;
+		assigned-clocks = <&topckgen CLK_TOP_ETHER_125M_SEL>,
+				  <&topckgen CLK_TOP_ETHER_50M_SEL>;
+		assigned-clock-parents = <&topckgen CLK_TOP_ETHERPLL_125M>,
+					 <&topckgen CLK_TOP_APLL1_D3>;
+		mediatek,pericfg = <&pericfg>;
+		mediatek,tx-delay = <9>;
+		mediatek,rx-delay = <9>;
+		mediatek,fine-tune;
+		mediatek,rmii-rxc;
+		mediatek,txc-inverse;
+		mediatek,rxc-inverse;
+		snps,txpbl = <32>;
+		snps,rxpbl = <32>;
+		snps,reset-gpio = <&pio 87 GPIO_ACTIVE_LOW>;
+		snps,reset-active-low;
+	};
-- 
1.7.9.5

Re: [v4, PATCH 2/2] dt-binding: mediatek-dwmac: add binding document for MediaTek MT2712 DWMAC

[Andrew Lunn]

> +Optional properties:
> +- mediatek,tx-delay: TX clock delay macro value. Range is 0~31. Default is 0.
> +	It should be defined for rgmii/rgmii-rxid/mii interface.
> +- mediatek,rx-delay: RX clock delay macro value. Range is 0~31. Default is 0.
> +	It should be defined for rgmii/rgmii-txid/mii/rmii interface.
> +- mediatek,fine-tune: boolean property, if present indicates that fine delay
> +	is selected for rgmii interface.
> +	If present, tx-delay/rx-delay is 170+/-50ps per stage.
> +	Else tx-delay/rx-delay of coarse delay macro is 0.55+/-0.2ns per stage.
> +	This property do not apply to non-rgmii PHYs.
> +	Only coarse-tune delay is supported for mii/rmii PHYs.

Didn't Rob say to express the delay in pS, and have the driver convert
that to values to put into registers. That is what i would prefer.

     Andrew