powerpc: Add support for GENERIC_EARLY_IOREMAP

Add support for GENERIC_EARLY_IOREMAP.

Let's define 16 slots of 256Kbytes each for early ioremap.
Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/412c7eaa6a373d8f82a3c3ee01e6a65a1a6589de.1568295907.git.christophe.leroy@c-s.fr

arch/powerpc/Kconfig

@@ -161,6 +161,7 @@ config PPC
 	select GENERIC_CMOS_UPDATE
 	select GENERIC_CPU_AUTOPROBE
 	select GENERIC_CPU_VULNERABILITIES	if PPC_BARRIER_NOSPEC
+	select GENERIC_EARLY_IOREMAP
 	select GENERIC_IRQ_SHOW
 	select GENERIC_IRQ_SHOW_LEVEL
 	select GENERIC_PCI_IOMAP		if PCI

arch/powerpc/include/asm/Kbuild

@@ -12,3 +12,4 @@ generic-y += mcs_spinlock.h
 generic-y += preempt.h
 generic-y += vtime.h
 generic-y += msi.h
+generic-y += early_ioremap.h

arch/powerpc/include/asm/fixmap.h

@@ -15,6 +15,7 @@
 #define _ASM_FIXMAP_H
 
 #ifndef __ASSEMBLY__
+#include <linux/sizes.h>
 #include <asm/page.h>
 #include <asm/pgtable.h>
 #ifdef CONFIG_HIGHMEM
@@ -64,6 +65,14 @@ enum fixed_addresses {
 		       FIX_IMMR_SIZE,
 #endif
 	/* FIX_PCIE_MCFG, */
+	__end_of_permanent_fixed_addresses,
+
+#define NR_FIX_BTMAPS		(SZ_256K / PAGE_SIZE)
+#define FIX_BTMAPS_SLOTS	16
+#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
 };
 
@@ -71,6 +80,7 @@ enum fixed_addresses {
 #define FIXADDR_START		(FIXADDR_TOP - __FIXADDR_SIZE)
 
 #define FIXMAP_PAGE_NOCACHE PAGE_KERNEL_NCG
+#define FIXMAP_PAGE_IO	PAGE_KERNEL_NCG
 
 #include <asm-generic/fixmap.h>
 
@@ -85,5 +95,7 @@ static inline void __set_fixmap(enum fixed_addresses idx,
 	map_kernel_page(__fix_to_virt(idx), phys, flags);
 }
 
+#define __early_set_fixmap	__set_fixmap
+
 #endif /* !__ASSEMBLY__ */
 #endif

arch/powerpc/kernel/setup_32.c

@@ -44,6 +44,7 @@
 #include <asm/asm-prototypes.h>
 #include <asm/kdump.h>
 #include <asm/feature-fixups.h>
+#include <asm/early_ioremap.h>
 
 #include "setup.h"
 
@@ -80,6 +81,8 @@ notrace void __init machine_init(u64 dt_ptr)
 	/* Configure static keys first, now that we're relocated. */
 	setup_feature_keys();
 
+	early_ioremap_setup();
+
 	/* Enable early debugging if any specified (see udbg.h) */
 	udbg_early_init();
 

arch/powerpc/kernel/setup_64.c

@@ -65,6 +65,7 @@
 #include <asm/hw_irq.h>
 #include <asm/feature-fixups.h>
 #include <asm/kup.h>
+#include <asm/early_ioremap.h>
 
 #include "setup.h"
 
@@ -332,6 +333,8 @@ void __init early_setup(unsigned long dt_ptr)
 	apply_feature_fixups();
 	setup_feature_keys();
 
+	early_ioremap_setup();
+
 	/* Initialize the hash table or TLB handling */
 	early_init_mmu();