bootstd: Add an implementation of distro PXE boot

Add a bootmeth driver which handles distro boot from a network device, so
we can boot a bootflow using this commonly used mechanism.

In effect, this provides the same functionality as the 'pxe' command
and shares the same code. But the interface into it is via a bootmeth.

For now this requires the 'pxe' command be enabled. Future work may tidy
this up so that it can be used without CONFIG_CMDLINE being enabled.

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

boot/Kconfig

@@ -339,6 +339,16 @@ config BOOTMETH_DISTRO
 
 	  This provides a way to try out standard boot on an existing boot flow.
 
+config BOOTMETH_DISTRO_PXE
+	bool "Bootdev support for distro boot over network"
+	depends on CMD_PXE && CMD_NET && DM_ETH
+	default y
+	help
+	  Enables support for distro boot using bootdevs. This makes the
+	  bootdevs look for a 'extlinux/extlinux.conf' on the tftp server.
+
+	  This provides a way to try out standard boot on an existing boot flow.
+
 endif
 
 config LEGACY_IMAGE_FORMAT

boot/Makefile

@@ -25,6 +25,7 @@ obj-$(CONFIG_$(SPL_TPL_)BOOTSTD) += bootmeth-uclass.o
 obj-$(CONFIG_$(SPL_TPL_)BOOTSTD) += bootstd-uclass.o
 
 obj-$(CONFIG_$(SPL_TPL_)BOOTMETH_DISTRO) += bootmeth_distro.o
+obj-$(CONFIG_$(SPL_TPL_)BOOTMETH_DISTRO_PXE) += bootmeth_pxe.o
 
 obj-$(CONFIG_$(SPL_TPL_)OF_LIBFDT) += image-fdt.o
 obj-$(CONFIG_$(SPL_TPL_)FIT_SIGNATURE) += fdt_region.o

boot/bootmeth_pxe.c

@@ -0,0 +1,186 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Bootmethod for distro boot using PXE (network boot)
+ *
+ * Copyright 2021 Google LLC
+ * Written by Simon Glass <sjg@chromium.org>
+ */
+
+#define LOG_CATEGORY UCLASS_BOOTSTD
+
+#include <common.h>
+#include <bootdev.h>
+#include <bootflow.h>
+#include <bootmeth.h>
+#include <command.h>
+#include <distro.h>
+#include <dm.h>
+#include <fs.h>
+#include <log.h>
+#include <malloc.h>
+#include <mapmem.h>
+#include <mmc.h>
+#include <net.h>
+#include <pxe_utils.h>
+
+static int disto_pxe_getfile(struct pxe_context *ctx, const char *file_path,
+			     char *file_addr, ulong *sizep)
+{
+	struct distro_info *info = ctx->userdata;
+	ulong addr;
+	int ret;
+
+	addr = simple_strtoul(file_addr, NULL, 16);
+	ret = bootmeth_read_file(info->dev, info->bflow, file_path, addr,
+				 sizep);
+	if (ret)
+		return log_msg_ret("read", ret);
+
+	return 0;
+}
+
+static int distro_pxe_check(struct udevice *dev, struct bootflow_iter *iter)
+{
+	int ret;
+
+	/* This only works on network devices */
+	ret = bootflow_iter_uses_network(iter);
+	if (ret)
+		return log_msg_ret("net", ret);
+
+	return 0;
+}
+
+static int distro_pxe_read_bootflow(struct udevice *dev, struct bootflow *bflow)
+{
+	const char *addr_str;
+	char fname[200];
+	char *bootdir;
+	ulong addr;
+	ulong size;
+	char *buf;
+	int ret;
+
+	addr_str = env_get("pxefile_addr_r");
+	if (!addr_str)
+		return log_msg_ret("pxeb", -EPERM);
+	addr = simple_strtoul(addr_str, NULL, 16);
+
+	log_debug("calling pxe_get()\n");
+	ret = pxe_get(addr, &bootdir, &size);
+	log_debug("pxe_get() returned %d\n", ret);
+	if (ret)
+		return log_msg_ret("pxeb", ret);
+	bflow->size = size;
+
+	/* Use the directory of the dhcp bootdir as our subdir, if provided */
+	if (bootdir) {
+		const char *last_slash;
+		int path_len;
+
+		last_slash = strrchr(bootdir, '/');
+		if (last_slash) {
+			path_len = (last_slash - bootdir) + 1;
+			bflow->subdir = malloc(path_len + 1);
+			memcpy(bflow->subdir, bootdir, path_len);
+			bflow->subdir[path_len] = '\0';
+		}
+	}
+	snprintf(fname, sizeof(fname), "%s%s",
+		 bflow->subdir ? bflow->subdir : "", DISTRO_FNAME);
+
+	bflow->fname = strdup(fname);
+	if (!bflow->fname)
+		return log_msg_ret("name", -ENOMEM);
+
+	bflow->state = BOOTFLOWST_READY;
+
+	/* Allocate the buffer, including the \0 byte added by get_pxe_file() */
+	buf = malloc(size + 1);
+	if (!buf)
+		return log_msg_ret("buf", -ENOMEM);
+	memcpy(buf, map_sysmem(addr, 0), size + 1);
+	bflow->buf = buf;
+
+	return 0;
+}
+
+static int distro_pxe_read_file(struct udevice *dev, struct bootflow *bflow,
+				const char *file_path, ulong addr, ulong *sizep)
+{
+	char *tftp_argv[] = {"tftp", NULL, NULL, NULL};
+	struct pxe_context *ctx = dev_get_priv(dev);
+	char file_addr[17];
+	ulong size;
+	int ret;
+
+	sprintf(file_addr, "%lx", addr);
+	tftp_argv[1] = file_addr;
+	tftp_argv[2] = (void *)file_path;
+
+	if (do_tftpb(ctx->cmdtp, 0, 3, tftp_argv))
+		return -ENOENT;
+	ret = pxe_get_file_size(&size);
+	if (ret)
+		return log_msg_ret("tftp", ret);
+	if (size > *sizep)
+		return log_msg_ret("spc", -ENOSPC);
+	*sizep = size;
+
+	return 0;
+}
+
+static int distro_pxe_boot(struct udevice *dev, struct bootflow *bflow)
+{
+	struct pxe_context *ctx = dev_get_priv(dev);
+	struct cmd_tbl cmdtp = {};	/* dummy */
+	struct distro_info info;
+	ulong addr;
+	int ret;
+
+	addr = map_to_sysmem(bflow->buf);
+	info.dev = dev;
+	info.bflow = bflow;
+	info.cmdtp = &cmdtp;
+	ret = pxe_setup_ctx(ctx, &cmdtp, disto_pxe_getfile, &info, false,
+			    bflow->subdir);
+	if (ret)
+		return log_msg_ret("ctx", -EINVAL);
+
+	ret = pxe_process(ctx, addr, false);
+	if (ret)
+		return log_msg_ret("bread", -EINVAL);
+
+	return 0;
+}
+
+static int distro_bootmeth_pxe_bind(struct udevice *dev)
+{
+	struct bootmeth_uc_plat *plat = dev_get_uclass_plat(dev);
+
+	plat->desc = IS_ENABLED(CONFIG_BOOTSTD_FULL) ?
+		"PXE boot from a network device" : "PXE";
+
+	return 0;
+}
+
+static struct bootmeth_ops distro_bootmeth_pxe_ops = {
+	.check		= distro_pxe_check,
+	.read_bootflow	= distro_pxe_read_bootflow,
+	.read_file	= distro_pxe_read_file,
+	.boot		= distro_pxe_boot,
+};
+
+static const struct udevice_id distro_bootmeth_pxe_ids[] = {
+	{ .compatible = "u-boot,distro-pxe" },
+	{ }
+};
+
+U_BOOT_DRIVER(bootmeth_pxe) = {
+	.name		= "bootmeth_pxe",
+	.id		= UCLASS_BOOTMETH,
+	.of_match	= distro_bootmeth_pxe_ids,
+	.ops		= &distro_bootmeth_pxe_ops,
+	.bind		= distro_bootmeth_pxe_bind,
+	.priv_auto	= sizeof(struct pxe_context),
+};