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From:   Christophe Leroy <christophe.leroy@c-s.fr>
Subject: [PATCH v1 02/10] powerpc/mm: rework io-workaround invocation.
To:     Benjamin Herrenschmidt <benh@kernel.crashing.org>,
        Paul Mackerras <paulus@samba.org>,
        Michael Ellerman <mpe@ellerman.id.au>, npiggin@gmail.com
Cc:     linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org
Date:   Tue, 13 Aug 2019 20:11:34 +0000 (UTC)
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

ppc_md.ioremap() is only used for I/O workaround on CELL platform,
so indirect function call can be avoided.

This patch reworks the io-workaround and ioremap() functions to
use static keys for the activation of io-workaround.

When CONFIG_PPC_IO_WORKAROUNDS or CONFIG_PPC_INDIRECT_MMIO are not
selected, the I/O workaround ioremap() voids and the static key is
not used at all.

Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
---
 arch/powerpc/include/asm/io-workarounds.h | 19 +++++++++++++++++++
 arch/powerpc/include/asm/machdep.h        |  2 --
 arch/powerpc/kernel/io-workarounds.c      | 11 ++++++-----
 arch/powerpc/mm/pgtable_64.c              | 17 +++++++++--------
 4 files changed, 34 insertions(+), 15 deletions(-)

diff --git a/arch/powerpc/include/asm/io-workarounds.h b/arch/powerpc/include/asm/io-workarounds.h
index 01567ea4ceaf..ce337d17ac40 100644
--- a/arch/powerpc/include/asm/io-workarounds.h
+++ b/arch/powerpc/include/asm/io-workarounds.h
@@ -8,6 +8,7 @@
 #ifndef _IO_WORKAROUNDS_H
 #define _IO_WORKAROUNDS_H
 
+#ifdef CONFIG_PPC_IO_WORKAROUNDS
 #include <linux/io.h>
 #include <asm/pci-bridge.h>
 
@@ -32,4 +33,22 @@ extern int spiderpci_iowa_init(struct iowa_bus *, void *);
 #define SPIDER_PCI_DUMMY_READ		0x0810
 #define SPIDER_PCI_DUMMY_READ_BASE	0x0814
 
+#endif
+
+#if defined(CONFIG_PPC_IO_WORKAROUNDS) && defined(CONFIG_PPC_INDIRECT_MMIO)
+DECLARE_STATIC_KEY_FALSE(iowa_key);
+static inline bool iowa_is_active(void)
+{
+	return static_branch_unlikely(&iowa_key);
+}
+#else
+static inline bool iowa_is_active(void)
+{
+	return false;
+}
+#endif
+
+void __iomem *iowa_ioremap(phys_addr_t addr, unsigned long size,
+			   pgprot_t prot, void *caller);
+
 #endif /* _IO_WORKAROUNDS_H */
diff --git a/arch/powerpc/include/asm/machdep.h b/arch/powerpc/include/asm/machdep.h
index 3370df4bdaa0..657ec893bdcb 100644
--- a/arch/powerpc/include/asm/machdep.h
+++ b/arch/powerpc/include/asm/machdep.h
@@ -31,8 +31,6 @@ struct pci_host_bridge;
 struct machdep_calls {
 	char		*name;
 #ifdef CONFIG_PPC64
-	void __iomem *	(*ioremap)(phys_addr_t addr, unsigned long size,
-				   pgprot_t prot, void *caller);
 #ifdef CONFIG_PM
 	void		(*iommu_save)(void);
 	void		(*iommu_restore)(void);
diff --git a/arch/powerpc/kernel/io-workarounds.c b/arch/powerpc/kernel/io-workarounds.c
index fbd2d0007c52..8b5b2aa70840 100644
--- a/arch/powerpc/kernel/io-workarounds.c
+++ b/arch/powerpc/kernel/io-workarounds.c
@@ -18,6 +18,7 @@
 #include <asm/io-workarounds.h>
 #include <asm/pte-walk.h>
 
+DEFINE_STATIC_KEY_FALSE(iowa_key);
 
 #define IOWA_MAX_BUS	8
 
@@ -149,8 +150,8 @@ static const struct ppc_pci_io iowa_pci_io = {
 };
 
 #ifdef CONFIG_PPC_INDIRECT_MMIO
-static void __iomem *iowa_ioremap(phys_addr_t addr, unsigned long size,
-				  pgprot_t prot, void *caller)
+void __iomem *iowa_ioremap(phys_addr_t addr, unsigned long size,
+			   pgprot_t prot, void *caller)
 {
 	struct iowa_bus *bus;
 	void __iomem *res = __ioremap_caller(addr, size, prot, caller);
@@ -163,8 +164,6 @@ static void __iomem *iowa_ioremap(phys_addr_t addr, unsigned long size,
 	}
 	return res;
 }
-#else /* CONFIG_PPC_INDIRECT_MMIO */
-#define iowa_ioremap NULL
 #endif /* !CONFIG_PPC_INDIRECT_MMIO */
 
 /* Enable IO workaround */
@@ -175,7 +174,9 @@ static void io_workaround_init(void)
 	if (io_workaround_inited)
 		return;
 	ppc_pci_io = iowa_pci_io;
-	ppc_md.ioremap = iowa_ioremap;
+#ifdef CONFIG_PPC_INDIRECT_MMIO
+	static_branch_enable(&iowa_key);
+#endif
 	io_workaround_inited = 1;
 }
 
diff --git a/arch/powerpc/mm/pgtable_64.c b/arch/powerpc/mm/pgtable_64.c
index 11eb90ea2d4f..194efc6f39fb 100644
--- a/arch/powerpc/mm/pgtable_64.c
+++ b/arch/powerpc/mm/pgtable_64.c
@@ -35,6 +35,7 @@
 #include <asm/page.h>
 #include <asm/prom.h>
 #include <asm/io.h>
+#include <asm/io-workarounds.h>
 #include <asm/mmu_context.h>
 #include <asm/pgtable.h>
 #include <asm/mmu.h>
@@ -214,8 +215,8 @@ void __iomem * ioremap(phys_addr_t addr, unsigned long size)
 	pgprot_t prot = pgprot_noncached(PAGE_KERNEL);
 	void *caller = __builtin_return_address(0);
 
-	if (ppc_md.ioremap)
-		return ppc_md.ioremap(addr, size, prot, caller);
+	if (iowa_is_active())
+		return iowa_ioremap(addr, size, prot, caller);
 	return __ioremap_caller(addr, size, prot, caller);
 }
 
@@ -224,8 +225,8 @@ void __iomem * ioremap_wc(phys_addr_t addr, unsigned long size)
 	pgprot_t prot = pgprot_noncached_wc(PAGE_KERNEL);
 	void *caller = __builtin_return_address(0);
 
-	if (ppc_md.ioremap)
-		return ppc_md.ioremap(addr, size, prot, caller);
+	if (iowa_is_active())
+		return iowa_ioremap(addr, size, prot, caller);
 	return __ioremap_caller(addr, size, prot, caller);
 }
 
@@ -234,8 +235,8 @@ void __iomem *ioremap_coherent(phys_addr_t addr, unsigned long size)
 	pgprot_t prot = pgprot_cached(PAGE_KERNEL);
 	void *caller = __builtin_return_address(0);
 
-	if (ppc_md.ioremap)
-		return ppc_md.ioremap(addr, size, prot, caller);
+	if (iowa_is_active())
+		return iowa_ioremap(addr, size, prot, caller);
 	return __ioremap_caller(addr, size, prot, caller);
 }
 
@@ -256,8 +257,8 @@ void __iomem * ioremap_prot(phys_addr_t addr, unsigned long size,
 	 */
 	pte = pte_mkprivileged(pte);
 
-	if (ppc_md.ioremap)
-		return ppc_md.ioremap(addr, size, pte_pgprot(pte), caller);
+	if (iowa_is_active())
+		return iowa_ioremap(addr, size, pte_pgprot(pte), caller);
 	return __ioremap_caller(addr, size, pte_pgprot(pte), caller);
 }
 
-- 
2.13.3