asm-generic: architecture independent readq/writeq for 32bit environment

This provides unified readq()/writeq() helper functions for 32-bit
drivers.

For some cases, readq/writeq without atomicity is harmful, and order of
io access has to be specified explicitly.  So in this patch, new two
header files which contain non-atomic readq/writeq are added.

 - <asm-generic/io-64-nonatomic-lo-hi.h> provides non-atomic readq/
   writeq with the order of lower address -> higher address

 - <asm-generic/io-64-nonatomic-hi-lo.h> provides non-atomic readq/
   writeq with reversed order

This allows us to remove some readq()s that were added drivers when the
default non-atomic ones were removed in commit dbee8a0affd5 ("x86:
remove 32-bit versions of readq()/writeq()")

The drivers which need readq/writeq but can do with the non-atomic ones
must add the line:

  #include <asm-generic/io-64-nonatomic-lo-hi.h> /* or hi-lo.h */

But this will be nop in 64-bit environments, and no other #ifdefs are
required.  So I believe that this patch can solve the problem of
 1. driver-specific readq/writeq
 2. atomicity and order of io access

This patch is tested with building allyesconfig and allmodconfig as
ARCH=x86 and ARCH=i386 on top of tip/master.

Cc: Kashyap Desai <Kashyap.Desai@lsi.com>
Cc: Len Brown <lenb@kernel.org>
Cc: Ravi Anand <ravi.anand@qlogic.com>
Cc: Vikas Chaudhary <vikas.chaudhary@qlogic.com>
Cc: Matthew Garrett <mjg@redhat.com>
Cc: Jason Uhlenkott <juhlenko@akamai.com>
Cc: James Bottomley <James.Bottomley@parallels.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Roland Dreier <roland@purestorage.com>
Cc: James Bottomley <jbottomley@parallels.com>
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>
Cc: Matthew Wilcox <matthew.r.wilcox@intel.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Hitoshi Mitake <h.mitake@gmail.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

drivers/block/nvme.c

@@ -41,6 +41,8 @@
 #include <linux/types.h>
 #include <linux/version.h>
 
+#include <asm-generic/io-64-nonatomic-lo-hi.h>
+
 #define NVME_Q_DEPTH 1024
 #define SQ_SIZE(depth)		(depth * sizeof(struct nvme_command))
 #define CQ_SIZE(depth)		(depth * sizeof(struct nvme_completion))

drivers/edac/i3200_edac.c

@@ -15,6 +15,8 @@
 #include <linux/io.h>
 #include "edac_core.h"
 
+#include <asm-generic/io-64-nonatomic-lo-hi.h>
+
 #define I3200_REVISION        "1.1"
 
 #define EDAC_MOD_STR        "i3200_edac"
@@ -101,19 +103,6 @@ struct i3200_priv {
 
 static int nr_channels;
 
-#ifndef readq
-static inline __u64 readq(const volatile void __iomem *addr)
-{
-	const volatile u32 __iomem *p = addr;
-	u32 low, high;
-
-	low = readl(p);
-	high = readl(p + 1);
-
-	return low + ((u64)high << 32);
-}
-#endif
-
 static int how_many_channels(struct pci_dev *pdev)
 {
 	unsigned char capid0_8b; /* 8th byte of CAPID0 */

drivers/platform/x86/ibm_rtl.c

@@ -33,6 +33,8 @@
 #include <linux/mutex.h>
 #include <asm/bios_ebda.h>
 
+#include <asm-generic/io-64-nonatomic-lo-hi.h>
+
 static bool force;
 module_param(force, bool, 0);
 MODULE_PARM_DESC(force, "Force driver load, ignore DMI data");
@@ -83,19 +85,6 @@ static void __iomem *rtl_cmd_addr;
 static u8 rtl_cmd_type;
 static u8 rtl_cmd_width;
 
-#ifndef readq
-static inline __u64 readq(const volatile void __iomem *addr)
-{
-	const volatile u32 __iomem *p = addr;
-	u32 low, high;
-
-	low = readl(p);
-	high = readl(p + 1);
-
-	return low + ((u64)high << 32);
-}
-#endif
-
 static void __iomem *rtl_port_map(phys_addr_t addr, unsigned long len)
 {
 	if (rtl_cmd_type == RTL_ADDR_TYPE_MMIO)

drivers/platform/x86/intel_ips.c

@@ -77,6 +77,8 @@
 #include <asm/processor.h>
 #include "intel_ips.h"
 
+#include <asm-generic/io-64-nonatomic-lo-hi.h>
+
 #define PCI_DEVICE_ID_INTEL_THERMAL_SENSOR 0x3b32
 
 /*
@@ -344,19 +346,6 @@ struct ips_driver {
 static bool
 ips_gpu_turbo_enabled(struct ips_driver *ips);
 
-#ifndef readq
-static inline __u64 readq(const volatile void __iomem *addr)
-{
-	const volatile u32 __iomem *p = addr;
-	u32 low, high;
-
-	low = readl(p);
-	high = readl(p + 1);
-
-	return low + ((u64)high << 32);
-}
-#endif
-
 /**
  * ips_cpu_busy - is CPU busy?
  * @ips: IPS driver struct

drivers/scsi/qla4xxx/ql4_nx.c

@@ -10,6 +10,8 @@
 #include "ql4_def.h"
 #include "ql4_glbl.h"
 
+#include <asm-generic/io-64-nonatomic-lo-hi.h>
+
 #define MASK(n)		DMA_BIT_MASK(n)
 #define MN_WIN(addr)	(((addr & 0x1fc0000) >> 1) | ((addr >> 25) & 0x3ff))
 #define OCM_WIN(addr)	(((addr & 0x1ff0000) >> 1) | ((addr >> 25) & 0x3ff))
@@ -655,27 +657,6 @@ static int qla4_8xxx_pci_is_same_window(struct scsi_qla_host *ha,
 	return 0;
 }
 
-#ifndef readq
-static inline __u64 readq(const volatile void __iomem *addr)
-{
-	const volatile u32 __iomem *p = addr;
-	u32 low, high;
-
-	low = readl(p);
-	high = readl(p + 1);
-
-	return low + ((u64)high << 32);
-}
-#endif
-
-#ifndef writeq
-static inline void writeq(__u64 val, volatile void __iomem *addr)
-{
-	writel(val, addr);
-	writel(val >> 32, addr+4);
-}
-#endif
-
 static int qla4_8xxx_pci_mem_read_direct(struct scsi_qla_host *ha,
 		u64 off, void *data, int size)
 {

include/asm-generic/io-64-nonatomic-hi-lo.h

@@ -0,0 +1,28 @@
+#ifndef _ASM_IO_64_NONATOMIC_HI_LO_H_
+#define _ASM_IO_64_NONATOMIC_HI_LO_H_
+
+#include <linux/io.h>
+#include <asm-generic/int-ll64.h>
+
+#ifndef readq
+static inline __u64 readq(const volatile void __iomem *addr)
+{
+	const volatile u32 __iomem *p = addr;
+	u32 low, high;
+
+	high = readl(p + 1);
+	low = readl(p);
+
+	return low + ((u64)high << 32);
+}
+#endif
+
+#ifndef writeq
+static inline void writeq(__u64 val, volatile void __iomem *addr)
+{
+	writel(val >> 32, addr + 4);
+	writel(val, addr);
+}
+#endif
+
+#endif	/* _ASM_IO_64_NONATOMIC_HI_LO_H_ */

include/asm-generic/io-64-nonatomic-lo-hi.h

@@ -0,0 +1,28 @@
+#ifndef _ASM_IO_64_NONATOMIC_LO_HI_H_
+#define _ASM_IO_64_NONATOMIC_LO_HI_H_
+
+#include <linux/io.h>
+#include <asm-generic/int-ll64.h>
+
+#ifndef readq
+static inline __u64 readq(const volatile void __iomem *addr)
+{
+	const volatile u32 __iomem *p = addr;
+	u32 low, high;
+
+	low = readl(p);
+	high = readl(p + 1);
+
+	return low + ((u64)high << 32);
+}
+#endif
+
+#ifndef writeq
+static inline void writeq(__u64 val, volatile void __iomem *addr)
+{
+	writel(val, addr);
+	writel(val >> 32, addr + 4);
+}
+#endif
+
+#endif	/* _ASM_IO_64_NONATOMIC_LO_HI_H_ */