bootstd: ethernet: Add a bootdev driver

Add a bootdev driver for Ethernet. It can use the PXE boot mechanism to
locate a file, added later.

Signed-off-by: Simon Glass <sjg@chromium.org>

MAINTAINERS

@@ -707,6 +707,7 @@ F:	include/bootdev.h
 F:	include/bootflow.h
 F:	include/bootmeth.h
 F:	include/bootstd.h
+F:	net/eth_bootdevice.c
 
 BTRFS
 M:	Marek Behun <marek.behun@nic.cz>

net/Kconfig

@@ -25,6 +25,15 @@ config PROT_UDP
 	  Enable a generic udp framework that allows defining a custom
 	  handler for udp protocol.
 
+config BOOTDEV_ETH
+	bool "Enable bootdev for ethernet"
+	depends on BOOTSTD
+	default y
+	help
+	  Provide a bootdev for ethernet so that is it possible to boot
+	  an operationg system over the network, using the PXE (Preboot
+	  Execution Environment) protocol.
+
 config BOOTP_SEND_HOSTNAME
 	bool "Send hostname to DNS server"
 	help

net/Makefile

@@ -12,6 +12,7 @@ obj-$(CONFIG_CMD_DNS)  += dns.o
 obj-$(CONFIG_DM_DSA)   += dsa-uclass.o
 ifdef CONFIG_DM_ETH
 obj-$(CONFIG_NET)      += eth-uclass.o
+obj-$(CONFIG_$(SPL_TPL_)BOOTDEV_ETH) += eth_bootdev.o
 else
 obj-$(CONFIG_NET)      += eth_legacy.o
 endif

net/eth-uclass.c

@@ -8,6 +8,7 @@
 #define LOG_CATEGORY UCLASS_ETH
 
 #include <common.h>
+#include <bootdev.h>
 #include <bootstage.h>
 #include <dm.h>
 #include <env.h>
@@ -473,6 +474,8 @@ int eth_initialize(void)
 
 static int eth_post_bind(struct udevice *dev)
 {
+	int ret;
+
 	if (strchr(dev->name, ' ')) {
 		printf("\nError: eth device name \"%s\" has a space!\n",
 		       dev->name);
@@ -482,6 +485,11 @@ static int eth_post_bind(struct udevice *dev)
 #ifdef CONFIG_DM_ETH_PHY
 	eth_phy_binds_nodes(dev);
 #endif
+	if (CONFIG_IS_ENABLED(BOOTDEV_ETH)) {
+		ret = bootdev_setup_for_dev(dev, "eth_bootdev");
+		if (ret)
+			return log_msg_ret("bootdev", ret);
+	}
 
 	return 0;
 }

net/eth_bootdev.c

+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Bootdevice for ethernet (uses PXE)
+ *
+ * Copyright 2021 Google LLC
+ * Written by Simon Glass <sjg@chromium.org>
+ */
+
+#include <common.h>
+#include <bootdev.h>
+#include <bootflow.h>
+#include <command.h>
+#include <bootmeth.h>
+#include <distro.h>
+#include <dm.h>
+#include <log.h>
+#include <net.h>
+
+static int eth_get_bootflow(struct udevice *dev, struct bootflow_iter *iter,
+			    struct bootflow *bflow)
+{
+	char name[60];
+	int ret;
+
+	/* Must be an Ethernet device */
+	ret = bootflow_iter_uses_network(iter);
+	if (ret)
+		return log_msg_ret("net", ret);
+
+	ret = bootmeth_check(bflow->method, iter);
+	if (ret)
+		return log_msg_ret("check", ret);
+
+	/*
+	 * Like distro boot, this assumes there is only one Ethernet device.
+	 * In this case, that means that @eth is ignored
+	 */
+
+	snprintf(name, sizeof(name), "%s.%d", dev->name, iter->part);
+	bflow->name = strdup(name);
+	if (!bflow->name)
+		return log_msg_ret("name", -ENOMEM);
+
+	/*
+	 * There is not a direct interface to the network stack so run
+	 * everything through the command-line interpreter for now.
+	 *
+	 * Don't bother checking the result of dhcp. It can fail with:
+	 *
+	 * DHCP client bound to address 192.168.4.50 (4 ms)
+	 * *** Warning: no boot file name; using 'C0A80432.img'
+	 * Using smsc95xx_eth device
+	 * TFTP from server 192.168.4.1; our IP address is 192.168.4.50
+	 * Filename 'C0A80432.img'.
+	 * Load address: 0x200000
+	 * Loading: *
+	 * TFTP error: 'File not found' (1)
+	 *
+	 * This is not a real failure, since we don't actually care if the
+	 * boot file exists.
+	 */
+	log_debug("running dhcp\n");
+	run_command("dhcp", 0);
+	bflow->state = BOOTFLOWST_MEDIA;
+
+	/* See distro_pxe_read_bootflow() for the standard impl of this */
+	log_debug("dhcp complete - reading bootflow with method %s\n",
+		  bflow->method->name);
+	ret = bootmeth_read_bootflow(bflow->method, bflow);
+	log_debug("reading bootflow returned %d\n", ret);
+	if (ret)
+		return log_msg_ret("method", ret);
+
+	return 0;
+}
+
+static int eth_bootdev_bind(struct udevice *dev)
+{
+	struct bootdev_uc_plat *ucp = dev_get_uclass_plat(dev);
+
+	ucp->prio = BOOTDEVP_4_NET_BASE;
+
+	return 0;
+}
+
+struct bootdev_ops eth_bootdev_ops = {
+	.get_bootflow	= eth_get_bootflow,
+};
+
+static const struct udevice_id eth_bootdev_ids[] = {
+	{ .compatible = "u-boot,bootdev-eth" },
+	{ }
+};
+
+U_BOOT_DRIVER(eth_bootdev) = {
+	.name		= "eth_bootdev",
+	.id		= UCLASS_BOOTDEV,
+	.ops		= &eth_bootdev_ops,
+	.bind		= eth_bootdev_bind,
+	.of_match	= eth_bootdev_ids,
+};