mb/qemu-i440fx: refactor fw_cfg logic as separate driver

The fw_cfg device can be used by other qemu boards outside i440fx (and
q35, which manually includes the code). Factor out the fw_cfg code as a
separate driver that qemu mainboards can enable.

Change-Id: I8c5c4cb5f5478abd21aab8e8d0b503db41d81d40
Signed-off-by: Carlos López <carlos.lopez@openchip.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/85673
Reviewed-by: Nicholas Chin <nic.c3.14@gmail.com>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>

src/include/device/fw_cfg.h

@@ -0,0 +1,12 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+#ifndef FW_CFG_H
+#define FW_CFG_H
+#include "fw_cfg_if.h"
+
+void fw_cfg_get(uint16_t entry, void *dst, int dstlen);
+int fw_cfg_check_file(FWCfgFile *file, const char *name);
+int fw_cfg_max_cpus(void);
+unsigned long fw_cfg_smbios_tables(int *handle, unsigned long *current);
+uintptr_t fw_cfg_tolud(void);
+
+#endif /* FW_CFG_H */

src/include/device/fw_cfg_if.h

@@ -0,0 +1,118 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+
+/*
+ * These are the qemu firmware config interface defines and structs.
+ * Copied over from qemu source tree,
+ * include/standard-headers/linux/qemu_fw_cfg.h and modified accordingly.
+ */
+#ifndef FW_CFG_IF_H
+#define FW_CFG_IF_H
+
+#include <stdint.h>
+
+enum fw_cfg_enum {
+	FW_CFG_SIGNATURE,
+	FW_CFG_ID,
+	FW_CFG_UUID,
+	FW_CFG_RAM_SIZE,
+	FW_CFG_NOGRAPHIC,
+	FW_CFG_NB_CPUS,
+	FW_CFG_MACHINE_ID,
+	FW_CFG_KERNEL_ADDR,
+	FW_CFG_KERNEL_SIZE,
+	FW_CFG_KERNEL_CMDLINE,
+	FW_CFG_INITRD_ADDR,
+	FW_CFG_INITRD_SIZE,
+	FW_CFG_BOOT_DEVICE,
+	FW_CFG_NUMA,
+	FW_CFG_BOOT_MENU,
+	FW_CFG_MAX_CPUS,
+	FW_CFG_KERNEL_ENTRY,
+	FW_CFG_KERNEL_DATA,
+	FW_CFG_INITRD_DATA,
+	FW_CFG_CMDLINE_ADDR,
+	FW_CFG_CMDLINE_SIZE,
+	FW_CFG_CMDLINE_DATA,
+	FW_CFG_SETUP_ADDR,
+	FW_CFG_SETUP_SIZE,
+	FW_CFG_SETUP_DATA,
+	FW_CFG_FILE_DIR
+};
+
+#define FW_CFG_FILE_FIRST       0x20
+#define FW_CFG_FILE_SLOTS       0x10
+#define FW_CFG_MAX_ENTRY        (FW_CFG_FILE_FIRST+FW_CFG_FILE_SLOTS)
+
+#define FW_CFG_WRITE_CHANNEL    0x4000
+#define FW_CFG_ARCH_LOCAL       0x8000
+#define FW_CFG_ENTRY_MASK       ~(FW_CFG_WRITE_CHANNEL | FW_CFG_ARCH_LOCAL)
+
+#define FW_CFG_ACPI_TABLES      (FW_CFG_ARCH_LOCAL + 0)
+#define FW_CFG_SMBIOS_ENTRIES   (FW_CFG_ARCH_LOCAL + 1)
+#define FW_CFG_IRQ0_OVERRIDE    (FW_CFG_ARCH_LOCAL + 2)
+#define FW_CFG_E820_TABLE       (FW_CFG_ARCH_LOCAL + 3)
+#define FW_CFG_HPET             (FW_CFG_ARCH_LOCAL + 4)
+
+#define FW_CFG_INVALID          0xffff
+
+/* width in bytes of fw_cfg control register */
+#define FW_CFG_CTL_SIZE         0x02
+
+/* fw_cfg "file name" is up to 56 characters (including terminating nul) */
+#define FW_CFG_MAX_FILE_PATH    56
+
+/* size in bytes of fw_cfg signature */
+#define FW_CFG_SIG_SIZE         4
+
+typedef struct FWCfgFile {
+    uint32_t  size;        /* file size */
+    uint16_t  select;      /* write this to 0x510 to read it */
+    uint16_t  reserved;
+    char      name[FW_CFG_MAX_FILE_PATH];
+} __packed FWCfgFile;
+
+typedef struct FWCfgFiles {
+    uint32_t  count;
+    FWCfgFile f[];
+} __packed FWCfgFiles;
+
+typedef struct FwCfgE820Entry {
+    uint64_t address;
+    uint64_t length;
+    uint32_t type;
+} __packed FwCfgE820Entry __attribute((__aligned__(4)));
+
+
+#define SMBIOS_FIELD_ENTRY 0
+#define SMBIOS_TABLE_ENTRY 1
+
+typedef struct FwCfgSmbios {
+	uint16_t length;
+	uint8_t  headertype;
+	uint8_t  tabletype;
+	uint16_t fieldoffset;
+} __packed FwCfgSmbios;
+
+/* FW_CFG_ID bits */
+#define FW_CFG_VERSION          0x01
+#define FW_CFG_VERSION_DMA      0x02
+
+/* FW_CFG_DMA_CONTROL bits */
+#define FW_CFG_DMA_CTL_ERROR    0x01
+#define FW_CFG_DMA_CTL_READ     0x02
+#define FW_CFG_DMA_CTL_SKIP     0x04
+#define FW_CFG_DMA_CTL_SELECT   0x08
+#define FW_CFG_DMA_CTL_WRITE    0x10
+
+#define FW_CFG_DMA_SIGNATURE    0x51454d5520434647ULL /* "QEMU CFG" */
+
+/* Control as first field allows for different structures selected by this
+ * field, which might be useful in the future
+ */
+typedef struct FwCfgDmaAccess {
+	uint32_t control;
+	uint32_t length;
+	uint64_t address;
+} __packed FwCfgDmaAccess;
+
+#endif /* FW_CFG_IF_H */