x86: qemu: add fw_cfg support

The QEMU fw_cfg interface allows the guest to retrieve various data
information from QEMU. For example, APCI/SMBios tables, number of online
cpus, kernel data and command line, etc.

This patch adds support for QEMU fw_cfg interface.

Signed-off-by: Miao Yan <yanmiaobest@gmail.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
Tested-by: Bin Meng <bmeng.cn@gmail.com>

arch/x86/cpu/qemu/Makefile

@@ -7,5 +7,5 @@
 ifndef CONFIG_EFI_STUB
 obj-y += car.o dram.o
 endif
-obj-y += qemu.o
+obj-y += fw_cfg.o qemu.o
 obj-$(CONFIG_GENERATE_ACPI_TABLE) += acpi.o dsdt.o

arch/x86/cpu/qemu/fw_cfg.c

@@ -0,0 +1,283 @@
+/*
+ * (C) Copyright 2015 Miao Yan <yanmiaoebst@gmail.com>
+ *
+ * SPDX-License-Identifier:	GPL-2.0+
+ */
+
+#include <common.h>
+#include <command.h>
+#include <errno.h>
+#include <malloc.h>
+#include <asm/io.h>
+#include <asm/fw_cfg.h>
+
+static bool fwcfg_present;
+static bool fwcfg_dma_present;
+
+/* Read configuration item using fw_cfg PIO interface */
+static void qemu_fwcfg_read_entry_pio(uint16_t entry,
+		uint32_t size, void *address)
+{
+	uint32_t i = 0;
+	uint8_t *data = address;
+
+	/*
+	 * writting FW_CFG_INVALID will cause read operation to resume at
+	 * last offset, otherwise read will start at offset 0
+	 */
+	if (entry != FW_CFG_INVALID)
+		outw(entry, FW_CONTROL_PORT);
+	while (size--)
+		data[i++] = inb(FW_DATA_PORT);
+}
+
+/* Read configuration item using fw_cfg DMA interface */
+static void qemu_fwcfg_read_entry_dma(uint16_t entry,
+		uint32_t size, void *address)
+{
+	struct fw_cfg_dma_access dma;
+
+	dma.length = cpu_to_be32(size);
+	dma.address = cpu_to_be64((uintptr_t)address);
+	dma.control = cpu_to_be32(FW_CFG_DMA_READ);
+
+	/*
+	 * writting FW_CFG_INVALID will cause read operation to resume at
+	 * last offset, otherwise read will start at offset 0
+	 */
+	if (entry != FW_CFG_INVALID)
+		dma.control |= cpu_to_be32(FW_CFG_DMA_SELECT | (entry << 16));
+
+	barrier();
+
+	debug("qemu_fwcfg_dma_read_entry: addr %p, length %u control 0x%x\n",
+	      address, size, be32_to_cpu(dma.control));
+
+	outl(cpu_to_be32((uint32_t)&dma), FW_DMA_PORT_HIGH);
+
+	while (be32_to_cpu(dma.control) & ~FW_CFG_DMA_ERROR)
+		__asm__ __volatile__ ("pause");
+}
+
+static bool qemu_fwcfg_present(void)
+{
+	uint32_t qemu;
+
+	qemu_fwcfg_read_entry_pio(FW_CFG_SIGNATURE, 4, &qemu);
+	return be32_to_cpu(qemu) == QEMU_FW_CFG_SIGNATURE;
+}
+
+static bool qemu_fwcfg_dma_present(void)
+{
+	uint8_t dma_enabled;
+
+	qemu_fwcfg_read_entry_pio(FW_CFG_ID, 1, &dma_enabled);
+	if (dma_enabled & FW_CFG_DMA_ENABLED)
+		return true;
+
+	return false;
+}
+
+static void qemu_fwcfg_read_entry(uint16_t entry,
+		uint32_t length, void *address)
+{
+	if (fwcfg_dma_present)
+		qemu_fwcfg_read_entry_dma(entry, length, address);
+	else
+		qemu_fwcfg_read_entry_pio(entry, length, address);
+}
+
+int qemu_fwcfg_online_cpus(void)
+{
+	uint16_t nb_cpus;
+
+	if (!fwcfg_present)
+		return -ENODEV;
+
+	qemu_fwcfg_read_entry(FW_CFG_NB_CPUS, 2, &nb_cpus);
+
+	return le16_to_cpu(nb_cpus);
+}
+
+/*
+ * This function prepares kernel for zboot. It loads kernel data
+ * to 'load_addr', initrd to 'initrd_addr' and kernel command
+ * line using qemu fw_cfg interface.
+ */
+static int qemu_fwcfg_setup_kernel(void *load_addr, void *initrd_addr)
+{
+	char *data_addr;
+	uint32_t setup_size, kernel_size, cmdline_size, initrd_size;
+
+	qemu_fwcfg_read_entry(FW_CFG_SETUP_SIZE, 4, &setup_size);
+	qemu_fwcfg_read_entry(FW_CFG_KERNEL_SIZE, 4, &kernel_size);
+
+	if (setup_size == 0 || kernel_size == 0) {
+		printf("warning: no kernel available\n");
+		return -1;
+	}
+
+	data_addr = load_addr;
+	qemu_fwcfg_read_entry(FW_CFG_SETUP_DATA,
+			      le32_to_cpu(setup_size), data_addr);
+	data_addr += le32_to_cpu(setup_size);
+
+	qemu_fwcfg_read_entry(FW_CFG_KERNEL_DATA,
+			      le32_to_cpu(kernel_size), data_addr);
+	data_addr += le32_to_cpu(kernel_size);
+
+	data_addr = initrd_addr;
+	qemu_fwcfg_read_entry(FW_CFG_INITRD_SIZE, 4, &initrd_size);
+	if (initrd_size == 0) {
+		printf("warning: no initrd available\n");
+	} else {
+		qemu_fwcfg_read_entry(FW_CFG_INITRD_DATA,
+				      le32_to_cpu(initrd_size), data_addr);
+		data_addr += le32_to_cpu(initrd_size);
+	}
+
+	qemu_fwcfg_read_entry(FW_CFG_CMDLINE_SIZE, 4, &cmdline_size);
+	if (cmdline_size) {
+		qemu_fwcfg_read_entry(FW_CFG_CMDLINE_DATA,
+				      le32_to_cpu(cmdline_size), data_addr);
+		/*
+		 * if kernel cmdline only contains '\0', (e.g. no -append
+		 * when invoking qemu), do not update bootargs
+		 */
+		if (*data_addr != '\0') {
+			if (setenv("bootargs", data_addr) < 0)
+				printf("warning: unable to change bootargs\n");
+		}
+	}
+
+	printf("loading kernel to address %p size %x", load_addr,
+	       le32_to_cpu(kernel_size));
+	if (initrd_size)
+		printf(" initrd %p size %x\n",
+		       initrd_addr,
+		       le32_to_cpu(initrd_size));
+	else
+		printf("\n");
+
+	return 0;
+}
+
+static int qemu_fwcfg_list_firmware(void)
+{
+	int i;
+	uint32_t count;
+	struct fw_cfg_files *files;
+
+	qemu_fwcfg_read_entry(FW_CFG_FILE_DIR, 4, &count);
+	if (!count)
+		return 0;
+
+	count = be32_to_cpu(count);
+	files = malloc(count * sizeof(struct fw_cfg_file));
+	if (!files)
+		return -ENOMEM;
+
+	files->count = count;
+	qemu_fwcfg_read_entry(FW_CFG_INVALID,
+			      count * sizeof(struct fw_cfg_file),
+			      files->files);
+
+	for (i = 0; i < files->count; i++)
+		printf("%-56s\n", files->files[i].name);
+	free(files);
+	return 0;
+}
+
+void qemu_fwcfg_init(void)
+{
+	fwcfg_present = qemu_fwcfg_present();
+	if (fwcfg_present)
+		fwcfg_dma_present = qemu_fwcfg_dma_present();
+}
+
+static int qemu_fwcfg_do_list(cmd_tbl_t *cmdtp, int flag,
+		int argc, char * const argv[])
+{
+	if (qemu_fwcfg_list_firmware() < 0)
+		return CMD_RET_FAILURE;
+
+	return 0;
+}
+
+static int qemu_fwcfg_do_cpus(cmd_tbl_t *cmdtp, int flag,
+		int argc, char * const argv[])
+{
+	int ret = qemu_fwcfg_online_cpus();
+	if (ret < 0) {
+		printf("QEMU fw_cfg interface not found\n");
+		return CMD_RET_FAILURE;
+	}
+
+	printf("%d cpu(s) online\n", qemu_fwcfg_online_cpus());
+
+	return 0;
+}
+
+static int qemu_fwcfg_do_load(cmd_tbl_t *cmdtp, int flag,
+		int argc, char * const argv[])
+{
+	char *env;
+	void *load_addr;
+	void *initrd_addr;
+
+	env = getenv("loadaddr");
+	load_addr = env ?
+		(void *)simple_strtoul(env, NULL, 16) :
+		(void *)CONFIG_LOADADDR;
+
+	env = getenv("ramdiskaddr");
+	initrd_addr = env ?
+		(void *)simple_strtoul(env, NULL, 16) :
+		(void *)CONFIG_RAMDISK_ADDR;
+
+	if (argc == 2) {
+		load_addr = (void *)simple_strtoul(argv[0], NULL, 16);
+		initrd_addr = (void *)simple_strtoul(argv[1], NULL, 16);
+	} else if (argc == 1) {
+		load_addr = (void *)simple_strtoul(argv[0], NULL, 16);
+	}
+
+	return qemu_fwcfg_setup_kernel(load_addr, initrd_addr);
+}
+
+static cmd_tbl_t fwcfg_commands[] = {
+	U_BOOT_CMD_MKENT(list, 0, 1, qemu_fwcfg_do_list, "", ""),
+	U_BOOT_CMD_MKENT(cpus, 0, 1, qemu_fwcfg_do_cpus, "", ""),
+	U_BOOT_CMD_MKENT(load, 2, 1, qemu_fwcfg_do_load, "", ""),
+};
+
+static int do_qemu_fw(cmd_tbl_t *cmdtp, int flag, int argc, char * const argv[])
+{
+	int ret;
+	cmd_tbl_t *fwcfg_cmd;
+
+	if (!fwcfg_present) {
+		printf("QEMU fw_cfg interface not found\n");
+		return CMD_RET_USAGE;
+	}
+
+	fwcfg_cmd = find_cmd_tbl(argv[1], fwcfg_commands,
+				 ARRAY_SIZE(fwcfg_commands));
+	argc -= 2;
+	argv += 2;
+	if (!fwcfg_cmd || argc > fwcfg_cmd->maxargs)
+		return CMD_RET_USAGE;
+
+	ret = fwcfg_cmd->cmd(fwcfg_cmd, flag, argc, argv);
+
+	return cmd_process_error(fwcfg_cmd, ret);
+}
+
+U_BOOT_CMD(
+	qfw,	4,	1,	do_qemu_fw,
+	"QEMU firmware interface",
+	"<command>\n"
+	"    - list                             : print firmware(s) currently loaded\n"
+	"    - cpus                             : print online cpu number\n"
+	"    - load <kernel addr> <initrd addr> : load kernel and initrd (if any), and setup for zboot\n"
+)

arch/x86/cpu/qemu/qemu.c

@@ -11,6 +11,7 @@
 #include <asm/processor.h>
 #include <asm/arch/device.h>
 #include <asm/arch/qemu.h>
+#include <asm/fw_cfg.h>
 
 static bool i440fx;
 
@@ -57,6 +58,8 @@ static void qemu_chipset_init(void)
 		x86_pci_write_config32(PCI_BDF(0, 0, 0), PCIEX_BAR,
 				       CONFIG_PCIE_ECAM_BASE | BAR_EN);
 	}
+
+	qemu_fwcfg_init();
 }
 
 int arch_cpu_init(void)

arch/x86/include/asm/fw_cfg.h

@@ -0,0 +1,93 @@
+/*
+ * (C) Copyright 2015 Miao Yan <yanmiaobest@gmail.com>
+ *
+ * SPDX-License-Identifier:	GPL-2.0+
+ */
+
+#ifndef __FW_CFG__
+#define __FW_CFG__
+
+#define FW_CONTROL_PORT	0x510
+#define FW_DATA_PORT		0x511
+#define FW_DMA_PORT_LOW	0x514
+#define FW_DMA_PORT_HIGH	0x518
+
+enum qemu_fwcfg_items {
+	FW_CFG_SIGNATURE	= 0x00,
+	FW_CFG_ID		= 0x01,
+	FW_CFG_UUID		= 0x02,
+	FW_CFG_RAM_SIZE		= 0x03,
+	FW_CFG_NOGRAPHIC	= 0x04,
+	FW_CFG_NB_CPUS		= 0x05,
+	FW_CFG_MACHINE_ID	= 0x06,
+	FW_CFG_KERNEL_ADDR	= 0x07,
+	FW_CFG_KERNEL_SIZE	= 0x08,
+	FW_CFG_KERNEL_CMDLINE   = 0x09,
+	FW_CFG_INITRD_ADDR	= 0x0a,
+	FW_CFG_INITRD_SIZE	= 0x0b,
+	FW_CFG_BOOT_DEVICE	= 0x0c,
+	FW_CFG_NUMA		= 0x0d,
+	FW_CFG_BOOT_MENU	= 0x0e,
+	FW_CFG_MAX_CPUS		= 0x0f,
+	FW_CFG_KERNEL_ENTRY	= 0x10,
+	FW_CFG_KERNEL_DATA	= 0x11,
+	FW_CFG_INITRD_DATA	= 0x12,
+	FW_CFG_CMDLINE_ADDR	= 0x13,
+	FW_CFG_CMDLINE_SIZE	= 0x14,
+	FW_CFG_CMDLINE_DATA	= 0x15,
+	FW_CFG_SETUP_ADDR	= 0x16,
+	FW_CFG_SETUP_SIZE	= 0x17,
+	FW_CFG_SETUP_DATA	= 0x18,
+	FW_CFG_FILE_DIR		= 0x19,
+	FW_CFG_FILE_FIRST	= 0x20,
+	FW_CFG_WRITE_CHANNEL	= 0x4000,
+	FW_CFG_ARCH_LOCAL	= 0x8000,
+	FW_CFG_INVALID		= 0xffff,
+};
+
+#define FW_CFG_FILE_SLOTS	0x10
+#define FW_CFG_MAX_ENTRY	(FW_CFG_FILE_FIRST + FW_CFG_FILE_SLOTS)
+#define FW_CFG_ENTRY_MASK	 ~(FW_CFG_WRITE_CHANNEL | FW_CFG_ARCH_LOCAL)
+
+#define FW_CFG_MAX_FILE_PATH	56
+
+#define QEMU_FW_CFG_SIGNATURE	(('Q' << 24) | ('E' << 16) | ('M' << 8) | 'U')
+
+#define FW_CFG_DMA_ERROR	(1 << 0)
+#define FW_CFG_DMA_READ	(1 << 1)
+#define FW_CFG_DMA_SKIP	(1 << 2)
+#define FW_CFG_DMA_SELECT	(1 << 3)
+
+#define FW_CFG_DMA_ENABLED	(1 << 1)
+
+struct fw_cfg_file {
+	__be32 size;
+	__be16 select;
+	__be16 reserved;
+	char name[FW_CFG_MAX_FILE_PATH];
+};
+
+struct fw_cfg_files {
+	__be32 count;
+	struct fw_cfg_file files[];
+};
+
+struct fw_cfg_dma_access {
+	__be32 control;
+	__be32 length;
+	__be64 address;
+};
+
+/**
+ * Initialize QEMU fw_cfg interface
+ */
+void qemu_fwcfg_init(void);
+
+/**
+ * Get system cpu number
+ *
+ * @return:   cpu number in system
+ */
+int qemu_fwcfg_online_cpus(void);
+
+#endif