liteeth: LiteX Ethernet device

LiteX is a soft system-on-chip that targets FPGAs. LiteETH is a basic
network device that is commonly used in LiteX designs.

Signed-off-by: Joel Stanley <joel@jms.id.au>
Reviewed-by: Ramon Fried <rfried.dev@gmail.com>

drivers/net/Kconfig

@@ -438,6 +438,11 @@ config KSZ9477
 	  This driver implements a DSA switch driver for the KSZ9477 family
 	  of GbE switches using the I2C interface.
 
+config LITEETH
+	bool "LiteX LiteEth Ethernet MAC"
+	help
+	 Driver for the LiteEth Ethernet MAC from LiteX.
+
 config MVGBE
 	bool "Marvell Orion5x/Kirkwood network interface support"
 	depends on ARCH_KIRKWOOD || ARCH_ORION5X

drivers/net/Makefile

@@ -47,6 +47,7 @@ obj-$(CONFIG_GMAC_ROCKCHIP) += gmac_rockchip.o
 obj-$(CONFIG_HIGMACV300_ETH) += higmacv300.o
 obj-$(CONFIG_KS8851_MLL) += ks8851_mll.o
 obj-$(CONFIG_KSZ9477) += ksz9477.o
+obj-$(CONFIG_LITEETH) += liteeth.o
 obj-$(CONFIG_MACB) += macb.o
 obj-$(CONFIG_MCFFEC) += mcffec.o mcfmii.o
 obj-$(CONFIG_MDIO_IPQ4019) += mdio-ipq4019.o

drivers/net/liteeth.c

@@ -0,0 +1,214 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * LiteX Liteeth Ethernet
+ *
+ * Copyright 2021 Joel Stanley <joel@jms.id.au>, IBM Corp.
+ */
+
+#include <linux/litex.h>
+
+#include <dm.h>
+#include <dm/device_compat.h>
+#include <net.h>
+
+#define LITEETH_WRITER_SLOT       0x00
+#define LITEETH_WRITER_LENGTH     0x04
+#define LITEETH_WRITER_ERRORS     0x08
+#define LITEETH_WRITER_EV_STATUS  0x0C
+#define LITEETH_WRITER_EV_PENDING 0x10
+#define LITEETH_WRITER_EV_ENABLE  0x14
+#define LITEETH_READER_START      0x18
+#define LITEETH_READER_READY      0x1C
+#define LITEETH_READER_LEVEL      0x20
+#define LITEETH_READER_SLOT       0x24
+#define LITEETH_READER_LENGTH     0x28
+#define LITEETH_READER_EV_STATUS  0x2C
+#define LITEETH_READER_EV_PENDING 0x30
+#define LITEETH_READER_EV_ENABLE  0x34
+#define LITEETH_PREAMBLE_CRC      0x38
+#define LITEETH_PREAMBLE_ERRORS   0x3C
+#define LITEETH_CRC_ERRORS        0x40
+
+struct liteeth {
+	struct udevice *dev;
+
+	void __iomem *base;
+	u32 slot_size;
+
+	/* Tx */
+	u32 tx_slot;
+	u32 num_tx_slots;
+	void __iomem *tx_base;
+
+	/* Rx */
+	u32 rx_slot;
+	u32 num_rx_slots;
+	void __iomem *rx_base;
+};
+
+static int liteeth_recv(struct udevice *dev, int flags, uchar **packetp)
+{
+	struct liteeth *priv = dev_get_priv(dev);
+	u8 rx_slot;
+	int len;
+
+	if (!litex_read8(priv->base + LITEETH_WRITER_EV_PENDING)) {
+		debug("liteeth: No packet ready\n");
+		return -EAGAIN;
+	}
+
+	rx_slot = litex_read8(priv->base + LITEETH_WRITER_SLOT);
+	len = litex_read32(priv->base + LITEETH_WRITER_LENGTH);
+
+	debug("%s: slot %d len 0x%x\n", __func__, rx_slot, len);
+
+	*packetp = priv->rx_base + rx_slot * priv->slot_size;
+
+	return len;
+}
+
+static int liteeth_free_pkt(struct udevice *dev, uchar *packet, int length)
+{
+	struct liteeth *priv = dev_get_priv(dev);
+
+	litex_write8(priv->base + LITEETH_WRITER_EV_PENDING, 1);
+
+	return 0;
+}
+
+static int liteeth_start(struct udevice *dev)
+{
+	struct liteeth *priv = dev_get_priv(dev);
+
+	/* Clear pending events */
+	litex_write8(priv->base + LITEETH_WRITER_EV_PENDING, 1);
+	litex_write8(priv->base + LITEETH_READER_EV_PENDING, 1);
+
+	/* Enable events */
+	litex_write8(priv->base + LITEETH_WRITER_EV_ENABLE, 1);
+	litex_write8(priv->base + LITEETH_READER_EV_ENABLE, 1);
+
+	return 0;
+}
+
+static void liteeth_stop(struct udevice *dev)
+{
+	struct liteeth *priv = dev_get_priv(dev);
+
+	litex_write8(priv->base + LITEETH_WRITER_EV_ENABLE, 0);
+	litex_write8(priv->base + LITEETH_READER_EV_ENABLE, 0);
+}
+
+static int liteeth_send(struct udevice *dev, void *packet, int len)
+{
+	struct liteeth *priv = dev_get_priv(dev);
+	void __iomem *txbuffer;
+
+	if (!litex_read8(priv->base + LITEETH_READER_READY)) {
+		printf("liteeth: reader not ready\n");
+		return -EAGAIN;
+	}
+
+	/* Reject oversize packets */
+	if (unlikely(len > priv->slot_size))
+		return -EMSGSIZE;
+
+	txbuffer = priv->tx_base + priv->tx_slot * priv->slot_size;
+	memcpy_toio(txbuffer, packet, len);
+	litex_write8(priv->base + LITEETH_READER_SLOT, priv->tx_slot);
+	litex_write16(priv->base + LITEETH_READER_LENGTH, len);
+	litex_write8(priv->base + LITEETH_READER_START, 1);
+
+	priv->tx_slot = (priv->tx_slot + 1) % priv->num_tx_slots;
+
+	return 0;
+}
+
+static void liteeth_setup_slots(struct liteeth *priv)
+{
+	int err;
+
+	err = ofnode_read_u32(dev_ofnode(priv->dev), "litex,rx-slots", &priv->num_rx_slots);
+	if (err) {
+		dev_dbg(priv->dev, "unable to get litex,rx-slots, using 2\n");
+		priv->num_rx_slots = 2;
+	}
+
+	err = ofnode_read_u32(dev_ofnode(priv->dev), "litex,tx-slots", &priv->num_tx_slots);
+	if (err) {
+		dev_dbg(priv->dev, "unable to get litex,tx-slots, using 2\n");
+		priv->num_tx_slots = 2;
+	}
+
+	err = ofnode_read_u32(dev_ofnode(priv->dev), "litex,slot-size", &priv->slot_size);
+	if (err) {
+		dev_dbg(priv->dev, "unable to get litex,slot-size, using 0x800\n");
+		priv->slot_size = 0x800;
+	}
+}
+
+static int liteeth_remove(struct udevice *dev)
+{
+	liteeth_stop(dev);
+
+	return 0;
+}
+
+static const struct eth_ops liteeth_ops = {
+	.start = liteeth_start,
+	.stop = liteeth_stop,
+	.send = liteeth_send,
+	.recv = liteeth_recv,
+	.free_pkt = liteeth_free_pkt,
+};
+
+static int liteeth_of_to_plat(struct udevice *dev)
+{
+	struct eth_pdata *pdata = dev_get_plat(dev);
+	struct liteeth *priv = dev_get_priv(dev);
+	void __iomem *buf_base;
+
+	pdata->iobase = dev_read_addr(dev);
+
+	priv->dev = dev;
+
+	priv->base = dev_remap_addr_name(dev, "mac");
+	if (!priv->base) {
+		dev_err(dev, "failed to map registers\n");
+		return -EINVAL;
+	}
+
+	buf_base = dev_remap_addr_name(dev, "buffer");
+	if (!buf_base) {
+		dev_err(dev, "failed to map buffer\n");
+		return -EINVAL;
+	}
+
+	liteeth_setup_slots(priv);
+
+	/* Rx slots */
+	priv->rx_base = buf_base;
+	priv->rx_slot = 0;
+
+	/* Tx slots come after Rx slots */
+	priv->tx_base = buf_base + priv->num_rx_slots * priv->slot_size;
+	priv->tx_slot = 0;
+
+	return 0;
+}
+
+static const struct udevice_id liteeth_ids[] = {
+	{ .compatible = "litex,liteeth" },
+	{}
+};
+
+U_BOOT_DRIVER(liteeth) = {
+	.name = "liteeth",
+	.id = UCLASS_ETH,
+	.of_match = liteeth_ids,
+	.of_to_plat = liteeth_of_to_plat,
+	.plat_auto = sizeof(struct eth_pdata),
+	.remove = liteeth_remove,
+	.ops = &liteeth_ops,
+	.priv_auto = sizeof(struct liteeth),
+};

include/linux/litex.h

@@ -0,0 +1,84 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Common LiteX header providing
+ * helper functions for accessing CSRs.
+ *
+ * Copyright (C) 2019-2020 Antmicro <www.antmicro.com>
+ */
+
+#ifndef _LINUX_LITEX_H
+#define _LINUX_LITEX_H
+
+#include <linux/io.h>
+#include <asm/byteorder.h>
+
+static inline void _write_litex_subregister(u32 val, void __iomem *addr)
+{
+	writel((u32 __force)cpu_to_le32(val), addr);
+}
+
+static inline u32 _read_litex_subregister(void __iomem *addr)
+{
+	return le32_to_cpu((__le32 __force)readl(addr));
+}
+
+/*
+ * LiteX SoC Generator, depending on the configuration, can split a single
+ * logical CSR (Control&Status Register) into a series of consecutive physical
+ * registers.
+ *
+ * For example, in the configuration with 8-bit CSR Bus, a 32-bit aligned,
+ * 32-bit wide logical CSR will be laid out as four 32-bit physical
+ * subregisters, each one containing one byte of meaningful data.
+ *
+ * For Linux support, upstream LiteX enforces a 32-bit wide CSR bus, which
+ * means that only larger-than-32-bit CSRs will be split across multiple
+ * subregisters (e.g., a 64-bit CSR will be spread across two consecutive
+ * 32-bit subregisters).
+ *
+ * For details see: https://github.com/enjoy-digital/litex/wiki/CSR-Bus
+ */
+
+static inline void litex_write8(void __iomem *reg, u8 val)
+{
+	_write_litex_subregister(val, reg);
+}
+
+static inline void litex_write16(void __iomem *reg, u16 val)
+{
+	_write_litex_subregister(val, reg);
+}
+
+static inline void litex_write32(void __iomem *reg, u32 val)
+{
+	_write_litex_subregister(val, reg);
+}
+
+static inline void litex_write64(void __iomem *reg, u64 val)
+{
+	_write_litex_subregister(val >> 32, reg);
+	_write_litex_subregister(val, reg + 4);
+}
+
+static inline u8 litex_read8(void __iomem *reg)
+{
+	return _read_litex_subregister(reg);
+}
+
+static inline u16 litex_read16(void __iomem *reg)
+{
+	return _read_litex_subregister(reg);
+}
+
+static inline u32 litex_read32(void __iomem *reg)
+{
+	return _read_litex_subregister(reg);
+}
+
+static inline u64 litex_read64(void __iomem *reg)
+{
+	return ((u64)_read_litex_subregister(reg) << 32) |
+		_read_litex_subregister(reg + 4);
+}
+
+#endif /* _LINUX_LITEX_H */