riscv: Add opensbi firmware dynamic support

OpenSBI is the default firmware in Qemu and has various firmware loading
options. Currently, qemu loader uses fw_jump which has a compile time
pre-defined address where fdt & kernel image must reside. This puts a
constraint on image size of the Linux kernel depending on the fdt location
and available memory. However, fw_dynamic allows the loader to specify
the next stage location (i.e. Linux kernel/U-Boot) in memory and other
configurable boot options available in OpenSBI.

Add support for OpenSBI dynamic firmware loading support. This doesn't
break existing setup and fw_jump will continue to work as it is. Any
other firmware will continue to work without any issues as long as it
doesn't expect anything specific from loader in "a2" register.

Signed-off-by: Atish Patra <atish.patra@wdc.com>
Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
Reviewed-by: Bin Meng <bin.meng@windriver.com>
Tested-by: Bin Meng <bin.meng@windriver.com>
Message-Id: <20200701183949.398134-4-atish.patra@wdc.com>
Signed-off-by: Alistair Francis <alistair.francis@wdc.com>

1 files changed, 38 insertions, 4 deletions

diff --git a/hw/riscv/boot.c b/hw/riscv/boot.c
index c62f545..feff6e3 100644
--- a/hw/riscv/boot.c
+++ b/hw/riscv/boot.c
@@ -25,6 +25,7 @@
 #include "hw/boards.h"
 #include "hw/loader.h"
 #include "hw/riscv/boot.h"
+#include "hw/riscv/boot_opensbi.h"
 #include "elf.h"
 #include "sysemu/device_tree.h"
 #include "sysemu/qtest.h"
@@ -33,8 +34,10 @@
 
 #if defined(TARGET_RISCV32)
 # define KERNEL_BOOT_ADDRESS 0x80400000
+#define fw_dynamic_info_data(__val)     cpu_to_le32(__val)
 #else
 # define KERNEL_BOOT_ADDRESS 0x80200000
+#define fw_dynamic_info_data(__val)     cpu_to_le64(__val)
 #endif
 
 void riscv_find_and_load_firmware(MachineState *machine,
@@ -189,15 +192,45 @@ uint32_t riscv_load_fdt(hwaddr dram_base, uint64_t mem_size, void *fdt)
     return fdt_addr;
 }
 
+void riscv_rom_copy_firmware_info(hwaddr rom_base, hwaddr rom_size,
+                              uint32_t reset_vec_size, uint64_t kernel_entry)
+{
+    struct fw_dynamic_info dinfo;
+    size_t dinfo_len;
+
+    dinfo.magic = fw_dynamic_info_data(FW_DYNAMIC_INFO_MAGIC_VALUE);
+    dinfo.version = fw_dynamic_info_data(FW_DYNAMIC_INFO_VERSION);
+    dinfo.next_mode = fw_dynamic_info_data(FW_DYNAMIC_INFO_NEXT_MODE_S);
+    dinfo.next_addr = fw_dynamic_info_data(kernel_entry);
+    dinfo.options = 0;
+    dinfo.boot_hart = 0;
+    dinfo_len = sizeof(dinfo);
+
+    /**
+     * copy the dynamic firmware info. This information is specific to
+     * OpenSBI but doesn't break any other firmware as long as they don't
+     * expect any certain value in "a2" register.
+     */
+    if (dinfo_len > (rom_size - reset_vec_size)) {
+        error_report("not enough space to store dynamic firmware info");
+        exit(1);
+    }
+
+    rom_add_blob_fixed_as("mrom.finfo", &dinfo, dinfo_len,
+                           rom_base + reset_vec_size,
+                           &address_space_memory);
+}
+
 void riscv_setup_rom_reset_vec(hwaddr start_addr, hwaddr rom_base,
-                               hwaddr rom_size,
+                               hwaddr rom_size, uint64_t kernel_entry,
                                uint32_t fdt_load_addr, void *fdt)
 {
     int i;
 
     /* reset vector */
     uint32_t reset_vec[10] = {
-        0x00000297,                  /* 1:  auipc  t0, %pcrel_hi(dtb) */
+        0x00000297,                  /* 1:  auipc  t0, %pcrel_hi(fw_dyn) */
+        0x02828613,                  /*     addi   a2, t0, %pcrel_lo(1b) */
         0xf1402573,                  /*     csrr   a0, mhartid  */
 #if defined(TARGET_RISCV32)
         0x0202a583,                  /*     lw     a1, 32(t0) */
@@ -207,12 +240,11 @@ void riscv_setup_rom_reset_vec(hwaddr start_addr, hwaddr rom_base,
         0x0182b283,                  /*     ld     t0, 24(t0) */
 #endif
         0x00028067,                  /*     jr     t0 */
-        0x00000000,
         start_addr,                  /* start: .dword */
         0x00000000,
         fdt_load_addr,               /* fdt_laddr: .dword */
         0x00000000,
-                                     /* dtb: */
+                                     /* fw_dyn: */
     };
 
     /* copy in the reset vector in little_endian byte order */
@@ -221,6 +253,8 @@ void riscv_setup_rom_reset_vec(hwaddr start_addr, hwaddr rom_base,
     }
     rom_add_blob_fixed_as("mrom.reset", reset_vec, sizeof(reset_vec),
                           rom_base, &address_space_memory);
+    riscv_rom_copy_firmware_info(rom_base, rom_size, sizeof(reset_vec),
+                                 kernel_entry);
 
     return;
 }