summaryrefslogtreecommitdiffstats
path: root/drivers/firmware/efi/libstub/riscv-stub.c
diff options
context:
space:
mode:
Diffstat (limited to 'drivers/firmware/efi/libstub/riscv-stub.c')
-rw-r--r--drivers/firmware/efi/libstub/riscv-stub.c109
1 files changed, 109 insertions, 0 deletions
diff --git a/drivers/firmware/efi/libstub/riscv-stub.c b/drivers/firmware/efi/libstub/riscv-stub.c
new file mode 100644
index 000000000000..380e4e251399
--- /dev/null
+++ b/drivers/firmware/efi/libstub/riscv-stub.c
@@ -0,0 +1,109 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2020 Western Digital Corporation or its affiliates.
+ */
+
+#include <linux/efi.h>
+#include <linux/libfdt.h>
+
+#include <asm/efi.h>
+#include <asm/sections.h>
+
+#include "efistub.h"
+
+/*
+ * RISC-V requires the kernel image to placed 2 MB aligned base for 64 bit and
+ * 4MB for 32 bit.
+ */
+#ifdef CONFIG_64BIT
+#define MIN_KIMG_ALIGN SZ_2M
+#else
+#define MIN_KIMG_ALIGN SZ_4M
+#endif
+
+typedef void __noreturn (*jump_kernel_func)(unsigned int, unsigned long);
+
+static u32 hartid;
+
+static u32 get_boot_hartid_from_fdt(void)
+{
+ const void *fdt;
+ int chosen_node, len;
+ const fdt32_t *prop;
+
+ fdt = get_efi_config_table(DEVICE_TREE_GUID);
+ if (!fdt)
+ return U32_MAX;
+
+ chosen_node = fdt_path_offset(fdt, "/chosen");
+ if (chosen_node < 0)
+ return U32_MAX;
+
+ prop = fdt_getprop((void *)fdt, chosen_node, "boot-hartid", &len);
+ if (!prop || len != sizeof(u32))
+ return U32_MAX;
+
+ return fdt32_to_cpu(*prop);
+}
+
+efi_status_t check_platform_features(void)
+{
+ hartid = get_boot_hartid_from_fdt();
+ if (hartid == U32_MAX) {
+ efi_err("/chosen/boot-hartid missing or invalid!\n");
+ return EFI_UNSUPPORTED;
+ }
+ return EFI_SUCCESS;
+}
+
+void __noreturn efi_enter_kernel(unsigned long entrypoint, unsigned long fdt,
+ unsigned long fdt_size)
+{
+ unsigned long stext_offset = _start_kernel - _start;
+ unsigned long kernel_entry = entrypoint + stext_offset;
+ jump_kernel_func jump_kernel = (jump_kernel_func)kernel_entry;
+
+ /*
+ * Jump to real kernel here with following constraints.
+ * 1. MMU should be disabled.
+ * 2. a0 should contain hartid
+ * 3. a1 should DT address
+ */
+ csr_write(CSR_SATP, 0);
+ jump_kernel(hartid, fdt);
+}
+
+efi_status_t handle_kernel_image(unsigned long *image_addr,
+ unsigned long *image_size,
+ unsigned long *reserve_addr,
+ unsigned long *reserve_size,
+ efi_loaded_image_t *image)
+{
+ unsigned long kernel_size = 0;
+ unsigned long preferred_addr;
+ efi_status_t status;
+
+ kernel_size = _edata - _start;
+ *image_addr = (unsigned long)_start;
+ *image_size = kernel_size + (_end - _edata);
+
+ /*
+ * RISC-V kernel maps PAGE_OFFSET virtual address to the same physical
+ * address where kernel is booted. That's why kernel should boot from
+ * as low as possible to avoid wastage of memory. Currently, dram_base
+ * is occupied by the firmware. So the preferred address for kernel to
+ * boot is next aligned address. If preferred address is not available,
+ * relocate_kernel will fall back to efi_low_alloc_above to allocate
+ * lowest possible memory region as long as the address and size meets
+ * the alignment constraints.
+ */
+ preferred_addr = MIN_KIMG_ALIGN;
+ status = efi_relocate_kernel(image_addr, kernel_size, *image_size,
+ preferred_addr, MIN_KIMG_ALIGN, 0x0);
+
+ if (status != EFI_SUCCESS) {
+ efi_err("Failed to relocate kernel\n");
+ *image_size = 0;
+ }
+ return status;
+}