xen: pvblock: Add initial support for para-virtualized block driver

Add initial infrastructure for Xen para-virtualized block device.
This includes compile-time configuration and the skeleton for
the future driver implementation.
Add new class UCLASS_PVBLOCK which is going to be a parent for
virtual block devices.
Add new interface type IF_TYPE_PVBLOCK.

Implement basic driver setup by reading XenStore configuration.

Signed-off-by: Andrii Anisov <andrii_anisov@epam.com>
Signed-off-by: Anastasiia Lukianenko <anastasiia_lukianenko@epam.com>
Signed-off-by: Oleksandr Andrushchenko <oleksandr_andrushchenko@epam.com>

cmd/Kconfig

@@ -1370,6 +1370,13 @@ config CMD_USB_MASS_STORAGE
 	help
 	  USB mass storage support
 
+config CMD_PVBLOCK
+	bool "Xen para-virtualized block device"
+	depends on XEN
+	select PVBLOCK
+	help
+	  Xen para-virtualized block device support
+
 config CMD_VIRTIO
 	bool "virtio"
 	depends on VIRTIO

cmd/Makefile

@@ -174,6 +174,7 @@ obj-$(CONFIG_CMD_DFU) += dfu.o
 obj-$(CONFIG_CMD_GPT) += gpt.o
 obj-$(CONFIG_CMD_ETHSW) += ethsw.o
 obj-$(CONFIG_CMD_AXI) += axi.o
+obj-$(CONFIG_CMD_PVBLOCK) += pvblock.o
 
 # Power
 obj-$(CONFIG_CMD_PMIC) += pmic.o

cmd/pvblock.c

@@ -0,0 +1,30 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * (C) Copyright 2020 EPAM Systems Inc.
+ *
+ * XEN para-virtualized block device support
+ */
+
+#include <blk.h>
+#include <common.h>
+#include <command.h>
+
+/* Current I/O Device */
+static int pvblock_curr_device;
+
+int do_pvblock(struct cmd_tbl *cmdtp, int flag, int argc, char *const argv[])
+{
+	return blk_common_cmd(argc, argv, IF_TYPE_PVBLOCK,
+			      &pvblock_curr_device);
+}
+
+U_BOOT_CMD(pvblock, 5, 1, do_pvblock,
+	   "Xen para-virtualized block device",
+	   "info  - show available block devices\n"
+	   "pvblock device [dev] - show or set current device\n"
+	   "pvblock part [dev] - print partition table of one or all devices\n"
+	   "pvblock read  addr blk# cnt\n"
+	   "pvblock write addr blk# cnt - read/write `cnt'"
+	   " blocks starting at block `blk#'\n"
+	   "    to/from memory address `addr'");
+

common/board_r.c

@@ -49,6 +49,7 @@
 #include <nand.h>
 #include <of_live.h>
 #include <onenand_uboot.h>
+#include <pvblock.h>
 #include <scsi.h>
 #include <serial.h>
 #include <status_led.h>
@@ -475,6 +476,16 @@ static int initr_xen(void)
 	return 0;
 }
 #endif
+
+#ifdef CONFIG_PVBLOCK
+static int initr_pvblock(void)
+{
+	puts("PVBLOCK: ");
+	pvblock_init();
+	return 0;
+}
+#endif
+
 /*
  * Tell if it's OK to load the environment early in boot.
  *
@@ -774,6 +785,9 @@ static init_fnc_t init_sequence_r[] = {
 #endif
 #ifdef CONFIG_XEN
 	initr_xen,
+#endif
+#ifdef CONFIG_PVBLOCK
+	initr_pvblock,
 #endif
 	initr_env,
 #ifdef CONFIG_SYS_BOOTPARAMS_LEN

configs/xenguest_arm64_defconfig

@@ -14,6 +14,8 @@ CONFIG_CMD_BOOTD=n
 CONFIG_CMD_BOOTEFI=n
 CONFIG_CMD_BOOTEFI_HELLO_COMPILE=n
 CONFIG_CMD_ELF=n
+CONFIG_CMD_EXT4=y
+CONFIG_CMD_FAT=y
 CONFIG_CMD_GO=n
 CONFIG_CMD_RUN=n
 CONFIG_CMD_IMI=n
@@ -41,6 +43,8 @@ CONFIG_CMD_LZMADEC=n
 CONFIG_CMD_SAVEENV=n
 CONFIG_CMD_UMS=n
 
+CONFIG_CMD_PVBLOCK=y
+
 #CONFIG_USB=n
 # CONFIG_ISO_PARTITION is not set
 

disk/part.c

@@ -149,6 +149,7 @@ void dev_print (struct blk_desc *dev_desc)
 	case IF_TYPE_MMC:
 	case IF_TYPE_USB:
 	case IF_TYPE_NVME:
+	case IF_TYPE_PVBLOCK:
 		printf ("Vendor: %s Rev: %s Prod: %s\n",
 			dev_desc->vendor,
 			dev_desc->revision,
@@ -288,6 +289,9 @@ static void print_part_header(const char *type, struct blk_desc *dev_desc)
 	case IF_TYPE_NVME:
 		puts ("NVMe");
 		break;
+	case IF_TYPE_PVBLOCK:
+		puts("PV BLOCK");
+		break;
 	case IF_TYPE_VIRTIO:
 		puts("VirtIO");
 		break;

drivers/Kconfig

@@ -136,6 +136,8 @@ source "drivers/w1-eeprom/Kconfig"
 
 source "drivers/watchdog/Kconfig"
 
+source "drivers/xen/Kconfig"
+
 config PHYS_TO_BUS
 	bool "Custom physical to bus address mapping"
 	help

drivers/block/blk-uclass.c

@@ -28,6 +28,7 @@ static const char *if_typename_str[IF_TYPE_COUNT] = {
 	[IF_TYPE_NVME]		= "nvme",
 	[IF_TYPE_EFI]		= "efi",
 	[IF_TYPE_VIRTIO]	= "virtio",
+	[IF_TYPE_PVBLOCK]	= "pvblock",
 };
 
 static enum uclass_id if_type_uclass_id[IF_TYPE_COUNT] = {
@@ -43,6 +44,7 @@ static enum uclass_id if_type_uclass_id[IF_TYPE_COUNT] = {
 	[IF_TYPE_NVME]		= UCLASS_NVME,
 	[IF_TYPE_EFI]		= UCLASS_EFI,
 	[IF_TYPE_VIRTIO]	= UCLASS_VIRTIO,
+	[IF_TYPE_PVBLOCK]	= UCLASS_PVBLOCK,
 };
 
 static enum if_type if_typename_to_iftype(const char *if_typename)

drivers/xen/Kconfig

@@ -0,0 +1,10 @@
+config PVBLOCK
+	bool "Xen para-virtualized block device"
+	depends on DM
+	select BLK
+	select HAVE_BLOCK_DEVICE
+	help
+	  This driver implements the front-end of the Xen virtual
+	  block device driver. It communicates with a back-end driver
+	  in another domain which drives the actual block device.
+

drivers/xen/Makefile

@@ -6,3 +6,5 @@ obj-y += hypervisor.o
 obj-y += events.o
 obj-y += xenbus.o
 obj-y += gnttab.o
+
+obj-$(CONFIG_PVBLOCK) += pvblock.o

drivers/xen/pvblock.c

@@ -0,0 +1,120 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * (C) Copyright 2020 EPAM Systems Inc.
+ */
+#include <blk.h>
+#include <common.h>
+#include <dm.h>
+#include <dm/device-internal.h>
+
+#define DRV_NAME	"pvblock"
+#define DRV_NAME_BLK	"pvblock_blk"
+
+struct blkfront_dev {
+	char dummy;
+};
+
+static int init_blkfront(unsigned int devid, struct blkfront_dev *dev)
+{
+	return 0;
+}
+
+static void shutdown_blkfront(struct blkfront_dev *dev)
+{
+}
+
+ulong pvblock_blk_read(struct udevice *udev, lbaint_t blknr, lbaint_t blkcnt,
+		       void *buffer)
+{
+	return 0;
+}
+
+ulong pvblock_blk_write(struct udevice *udev, lbaint_t blknr, lbaint_t blkcnt,
+			const void *buffer)
+{
+	return 0;
+}
+
+static int pvblock_blk_bind(struct udevice *udev)
+{
+	return 0;
+}
+
+static int pvblock_blk_probe(struct udevice *udev)
+{
+	struct blkfront_dev *blk_dev = dev_get_priv(udev);
+	int ret;
+
+	ret = init_blkfront(0, blk_dev);
+	if (ret < 0)
+		return ret;
+	return 0;
+}
+
+static int pvblock_blk_remove(struct udevice *udev)
+{
+	struct blkfront_dev *blk_dev = dev_get_priv(udev);
+
+	shutdown_blkfront(blk_dev);
+	return 0;
+}
+
+static const struct blk_ops pvblock_blk_ops = {
+	.read	= pvblock_blk_read,
+	.write	= pvblock_blk_write,
+};
+
+U_BOOT_DRIVER(pvblock_blk) = {
+	.name			= DRV_NAME_BLK,
+	.id			= UCLASS_BLK,
+	.ops			= &pvblock_blk_ops,
+	.bind			= pvblock_blk_bind,
+	.probe			= pvblock_blk_probe,
+	.remove			= pvblock_blk_remove,
+	.priv_auto_alloc_size	= sizeof(struct blkfront_dev),
+	.flags			= DM_FLAG_OS_PREPARE,
+};
+
+/*******************************************************************************
+ * Para-virtual block device class
+ *******************************************************************************/
+
+void pvblock_init(void)
+{
+	struct driver_info info;
+	struct udevice *udev;
+	struct uclass *uc;
+	int ret;
+
+	/*
+	 * At this point Xen drivers have already initialized,
+	 * so we can instantiate the class driver and enumerate
+	 * virtual block devices.
+	 */
+	info.name = DRV_NAME;
+	ret = device_bind_by_name(gd->dm_root, false, &info, &udev);
+	if (ret < 0)
+		printf("Failed to bind " DRV_NAME ", ret: %d\n", ret);
+
+	/* Bootstrap virtual block devices class driver */
+	ret = uclass_get(UCLASS_PVBLOCK, &uc);
+	if (ret)
+		return;
+	uclass_foreach_dev_probe(UCLASS_PVBLOCK, udev);
+}
+
+static int pvblock_probe(struct udevice *udev)
+{
+	return 0;
+}
+
+U_BOOT_DRIVER(pvblock_drv) = {
+	.name		= DRV_NAME,
+	.id		= UCLASS_PVBLOCK,
+	.probe		= pvblock_probe,
+};
+
+UCLASS_DRIVER(pvblock) = {
+	.name		= DRV_NAME,
+	.id		= UCLASS_PVBLOCK,
+};

include/blk.h

@@ -33,6 +33,7 @@ enum if_type {
 	IF_TYPE_HOST,
 	IF_TYPE_NVME,
 	IF_TYPE_EFI,
+	IF_TYPE_PVBLOCK,
 	IF_TYPE_VIRTIO,
 
 	IF_TYPE_COUNT,			/* Number of interface types */

include/configs/xenguest_arm64.h

@@ -41,4 +41,12 @@
 #define CONFIG_CMDLINE_TAG            1
 #define CONFIG_INITRD_TAG             1
 
+#define CONFIG_CMD_RUN
+
+#undef CONFIG_EXTRA_ENV_SETTINGS
+#define CONFIG_EXTRA_ENV_SETTINGS	\
+	"loadimage=ext4load pvblock 0 0x90000000 /boot/Image;\0" \
+	"pvblockboot=run loadimage;" \
+		"booti 0x90000000 - 0x88000000;\0"
+
 #endif /* __XENGUEST_ARM64_H */

include/dm/uclass-id.h

@@ -123,6 +123,7 @@ enum uclass_id {
 	UCLASS_W1,		/* Dallas 1-Wire bus */
 	UCLASS_W1_EEPROM,	/* one-wire EEPROMs */
 	UCLASS_WDT,		/* Watchdog Timer driver */
+	UCLASS_PVBLOCK,		/* Xen virtual block device */
 
 	UCLASS_COUNT,
 	UCLASS_INVALID = -1,

include/pvblock.h

@@ -0,0 +1,17 @@
+/* SPDX-License-Identifier: GPL-2.0+
+ *
+ * (C) 2020 EPAM Systems Inc.
+ */
+
+#ifndef _PVBLOCK_H
+#define _PVBLOCK_H
+
+/**
+ * pvblock_init() - Initialize para-virtual block device class driver
+ *
+ * Bind PV block to UCLASS_ROOT device and probe all UCLASS_PVBLOCK
+ * virtual block devices.
+ */
+void pvblock_init(void);
+
+#endif /* _PVBLOCK_H */