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Subject[PATCH v5 2/9] RISC-V: Add early ioremap support
Date
UEFI uses early IO or memory mappings for runtime services before
normal ioremap() is usable. Add the necessary fixmap bindings and
pmd mappings 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 | 13 +++++++++++++
arch/riscv/include/asm/io.h | 1 +
arch/riscv/kernel/setup.c | 1 +
arch/riscv/mm/init.c | 33 +++++++++++++++++++++++++++++++++
6 files changed, 50 insertions(+)

diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
index 7b5905529146..15597f5f504f 100644
--- a/arch/riscv/Kconfig
+++ b/arch/riscv/Kconfig
@@ -37,6 +37,7 @@ config RISCV
select GENERIC_ARCH_TOPOLOGY if SMP
select GENERIC_ATOMIC64 if !64BIT
select GENERIC_CLOCKEVENTS
+ select GENERIC_EARLY_IOREMAP
select GENERIC_GETTIMEOFDAY if HAVE_GENERIC_VDSO
select GENERIC_IOREMAP
select GENERIC_IRQ_MULTI_HANDLER
diff --git a/arch/riscv/include/asm/Kbuild b/arch/riscv/include/asm/Kbuild
index 3d9410bb4de0..59dd7be55005 100644
--- a/arch/riscv/include/asm/Kbuild
+++ b/arch/riscv/include/asm/Kbuild
@@ -1,4 +1,5 @@
# SPDX-License-Identifier: GPL-2.0
+generic-y += early_ioremap.h
generic-y += extable.h
generic-y += flat.h
generic-y += kvm_para.h
diff --git a/arch/riscv/include/asm/fixmap.h b/arch/riscv/include/asm/fixmap.h
index 11613f38228a..54cbf07fb4e9 100644
--- a/arch/riscv/include/asm/fixmap.h
+++ b/arch/riscv/include/asm/fixmap.h
@@ -27,6 +27,19 @@ enum fixed_addresses {
FIX_TEXT_POKE1,
FIX_TEXT_POKE0,
FIX_EARLYCON_MEM_BASE,
+
+ __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 3835c3295dc5..c025a746a148 100644
--- a/arch/riscv/include/asm/io.h
+++ b/arch/riscv/include/asm/io.h
@@ -14,6 +14,7 @@
#include <linux/types.h>
#include <linux/pgtable.h>
#include <asm/mmiowb.h>
+#include <asm/early_ioremap.h>

/*
* MMIO access functions are separated out to break dependency cycles
diff --git a/arch/riscv/kernel/setup.c b/arch/riscv/kernel/setup.c
index 6a0ee2405813..c71788e6aff4 100644
--- a/arch/riscv/kernel/setup.c
+++ b/arch/riscv/kernel/setup.c
@@ -72,6 +72,7 @@ void __init setup_arch(char **cmdline_p)

*cmdline_p = boot_command_line;

+ early_ioremap_setup();
parse_early_param();

setup_bootmem();
diff --git a/arch/riscv/mm/init.c b/arch/riscv/mm/init.c
index 2b651f63f5c4..b75ebe8e7a92 100644
--- a/arch/riscv/mm/init.c
+++ b/arch/riscv/mm/init.c
@@ -403,6 +403,9 @@ asmlinkage void __init setup_vm(uintptr_t dtb_pa)
uintptr_t load_pa = (uintptr_t)(&_start);
uintptr_t load_sz = (uintptr_t)(&_end) - load_pa;
uintptr_t map_size = best_map_size(load_pa, MAX_EARLY_MAPPING_SIZE);
+#ifndef __PAGETABLE_PMD_FOLDED
+ pmd_t fix_bmap_spmd, fix_bmap_epmd;
+#endif

va_pa_offset = PAGE_OFFSET - load_pa;
pfn_base = PFN_DOWN(load_pa);
@@ -456,6 +459,36 @@ asmlinkage void __init setup_vm(uintptr_t dtb_pa)
pa + PGDIR_SIZE, PGDIR_SIZE, PAGE_KERNEL);
dtb_early_va = (void *)DTB_EARLY_BASE_VA + (dtb_pa & (PGDIR_SIZE - 1));
dtb_early_pa = dtb_pa;
+
+ /*
+ * Bootime fixmap only can handle PMD_SIZE mapping. Thus, boot-ioremap
+ * range can not span multiple pmds.
+ */
+ BUILD_BUG_ON((__fix_to_virt(FIX_BTMAP_BEGIN) >> PMD_SHIFT)
+ != (__fix_to_virt(FIX_BTMAP_END) >> PMD_SHIFT));
+
+#ifndef __PAGETABLE_PMD_FOLDED
+ /*
+ * Early ioremap fixmap is already created as it lies within first 2MB
+ * of fixmap region. We always map PMD_SIZE. Thus, both FIX_BTMAP_END
+ * FIX_BTMAP_BEGIN should lie in the same pmd. Verify that and warn
+ * the user if not.
+ */
+ fix_bmap_spmd = fixmap_pmd[pmd_index(__fix_to_virt(FIX_BTMAP_BEGIN))];
+ fix_bmap_epmd = fixmap_pmd[pmd_index(__fix_to_virt(FIX_BTMAP_END))];
+ if (pmd_val(fix_bmap_spmd) != pmd_val(fix_bmap_epmd)) {
+ WARN_ON(1);
+ pr_warn("fixmap btmap start [%08lx] != end [%08lx]\n",
+ pmd_val(fix_bmap_spmd), pmd_val(fix_bmap_epmd));
+ pr_warn("fix_to_virt(FIX_BTMAP_BEGIN): %08lx\n",
+ fix_to_virt(FIX_BTMAP_BEGIN));
+ pr_warn("fix_to_virt(FIX_BTMAP_END): %08lx\n",
+ fix_to_virt(FIX_BTMAP_END));
+
+ pr_warn("FIX_BTMAP_END: %d\n", FIX_BTMAP_END);
+ pr_warn("FIX_BTMAP_BEGIN: %d\n", FIX_BTMAP_BEGIN);
+ }
+#endif
}

static void __init setup_vm_final(void)
--
2.24.0
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