[RFC PATCH 3/5] RISC-V: Define fixmap bindings for generic early ioremap support

[Atish Patra <atish.patra@wdc.com>]

UEFI uses early IO or memory mappings for runtime services before
normal ioremap() is usable. This patch only adds minimum necessary
fixmap bindings and headers for generic ioremap support to work.

Signed-off-by: Atish Patra <atish.patra@wdc.com>
---
 arch/riscv/Kconfig              |  1 +
 arch/riscv/include/asm/Kbuild   |  1 +
 arch/riscv/include/asm/fixmap.h | 21 ++++++++++++++++++++-
 arch/riscv/include/asm/io.h     |  1 +
 4 files changed, 23 insertions(+), 1 deletion(-)

diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
index 27bfc7947e44..42c122170cfd 100644
--- a/arch/riscv/Kconfig
+++ b/arch/riscv/Kconfig
@@ -65,6 +65,7 @@ config RISCV
 	select ARCH_HAS_GCOV_PROFILE_ALL
 	select HAVE_COPY_THREAD_TLS
 	select HAVE_ARCH_KASAN if MMU && 64BIT
+	select GENERIC_EARLY_IOREMAP
 
 config ARCH_MMAP_RND_BITS_MIN
 	default 18 if 64BIT
diff --git a/arch/riscv/include/asm/Kbuild b/arch/riscv/include/asm/Kbuild
index ec0ca8c6ab64..517394390106 100644
--- a/arch/riscv/include/asm/Kbuild
+++ b/arch/riscv/include/asm/Kbuild
@@ -4,6 +4,7 @@ generic-y += checksum.h
 generic-y += compat.h
 generic-y += device.h
 generic-y += div64.h
+generic-y += early_ioremap.h
 generic-y += extable.h
 generic-y += flat.h
 generic-y += dma.h
diff --git a/arch/riscv/include/asm/fixmap.h b/arch/riscv/include/asm/fixmap.h
index 42d2c42f3cc9..7a4beb7e29a3 100644
--- a/arch/riscv/include/asm/fixmap.h
+++ b/arch/riscv/include/asm/fixmap.h
@@ -25,9 +25,28 @@ enum fixed_addresses {
 #define FIX_FDT_SIZE	SZ_1M
 	FIX_FDT_END,
 	FIX_FDT = FIX_FDT_END + FIX_FDT_SIZE / PAGE_SIZE - 1,
+	FIX_EARLYCON_MEM_BASE,
+
 	FIX_PTE,
 	FIX_PMD,
-	FIX_EARLYCON_MEM_BASE,
+	/*
+	 * Make sure that it is 2MB aligned.
+	 */
+#define NR_FIX_SZ_2M	(SZ_2M / PAGE_SIZE)
+	FIX_THOLE = NR_FIX_SZ_2M - FIX_PMD - 1,
+
+	__end_of_permanent_fixed_addresses,
+	/*
+	 * Temporary boot-time mappings, used by early_ioremap(),
+	 * before ioremap() is functional.
+	 */
+#define NR_FIX_BTMAPS		(SZ_256K / PAGE_SIZE)
+#define FIX_BTMAPS_SLOTS	7
+#define TOTAL_FIX_BTMAPS	(NR_FIX_BTMAPS * FIX_BTMAPS_SLOTS)
+
+	FIX_BTMAP_END = __end_of_permanent_fixed_addresses,
+	FIX_BTMAP_BEGIN = FIX_BTMAP_END + TOTAL_FIX_BTMAPS - 1,
+
 	__end_of_fixed_addresses
 };
 
diff --git a/arch/riscv/include/asm/io.h b/arch/riscv/include/asm/io.h
index 0f477206a4ed..047f414b6948 100644
--- a/arch/riscv/include/asm/io.h
+++ b/arch/riscv/include/asm/io.h
@@ -14,6 +14,7 @@
 #include <linux/types.h>
 #include <asm/mmiowb.h>
 #include <asm/pgtable.h>
+#include <asm/early_ioremap.h>
 
 /*
  * MMIO access functions are separated out to break dependency cycles
-- 
2.24.0