lib: Add generic PIO mapping method

41f8bba ("of/pci: Add pci_register_io_range() and
pci_pio_to_address()") added support for PCI I/O space mapped into CPU
physical memory space.  With that support, the I/O ranges configured for
PCI/PCIe hosts on some architectures can be mapped to logical PIO and
converted easily between CPU address and the corresponding logical PIO.
Based on this, PCI I/O port space can be accessed via in/out accessors that
use memory read/write.

But on some platforms, there are bus hosts that access I/O port space with
host-local I/O port addresses rather than memory addresses.

Add a more generic I/O mapping method to support those devices.  With this
patch, both the CPU addresses and the host-local port can be mapped into
the logical PIO space with different logical/fake PIOs.  After this, all
the I/O accesses to either PCI MMIO devices or host-local I/O peripherals
can be unified into the existing I/O accessors defined in asm-generic/io.h
and be redirected to the right device-specific hooks based on the input
logical PIO.

Tested-by: dann frazier <[email protected]>
Signed-off-by: Zhichang Yuan <[email protected]>
Signed-off-by: Gabriele Paoloni <[email protected]>
Signed-off-by: John Garry <[email protected]>
[bhelgaas: remove -EFAULT return from logic_pio_register_range() per
https://lkml.kernel.org/r/20180403143909.GA21171@ulmo, fix NULL pointer
checking per https://lkml.kernel.org/r/[email protected]]
Signed-off-by: Bjorn Helgaas <[email protected]>
Reviewed-by: Andy Shevchenko <[email protected]>

include/asm-generic/io.h

@@ -351,6 +351,8 @@ static inline void writesq(volatile void __iomem *addr, const void *buffer,
 #define IO_SPACE_LIMIT 0xffff
 #endif
 
+#include <linux/logic_pio.h>
+
 /*
  * {in,out}{b,w,l}() access little endian I/O. {in,out}{b,w,l}_p() can be
  * implemented on hardware that needs an additional delay for I/O accesses to

include/linux/logic_pio.h

@@ -0,0 +1,123 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Copyright (C) 2017 HiSilicon Limited, All Rights Reserved.
+ * Author: Gabriele Paoloni <[email protected]>
+ * Author: Zhichang Yuan <[email protected]>
+ */
+
+#ifndef __LINUX_LOGIC_PIO_H
+#define __LINUX_LOGIC_PIO_H
+
+#include <linux/fwnode.h>
+
+enum {
+	LOGIC_PIO_INDIRECT,		/* Indirect IO flag */
+	LOGIC_PIO_CPU_MMIO,		/* Memory-mapped IO flag */
+};
+
+struct logic_pio_hwaddr {
+	struct list_head list;
+	struct fwnode_handle *fwnode;
+	resource_size_t hw_start;
+	resource_size_t io_start;
+	resource_size_t size; /* range size populated */
+	unsigned long flags;
+
+	void *hostdata;
+	const struct logic_pio_host_ops *ops;
+};
+
+struct logic_pio_host_ops {
+	u32 (*in)(void *hostdata, unsigned long addr, size_t dwidth);
+	void (*out)(void *hostdata, unsigned long addr, u32 val,
+		    size_t dwidth);
+	u32 (*ins)(void *hostdata, unsigned long addr, void *buffer,
+		   size_t dwidth, unsigned int count);
+	void (*outs)(void *hostdata, unsigned long addr, const void *buffer,
+		     size_t dwidth, unsigned int count);
+};
+
+#ifdef CONFIG_INDIRECT_PIO
+u8 logic_inb(unsigned long addr);
+void logic_outb(u8 value, unsigned long addr);
+void logic_outw(u16 value, unsigned long addr);
+void logic_outl(u32 value, unsigned long addr);
+u16 logic_inw(unsigned long addr);
+u32 logic_inl(unsigned long addr);
+void logic_outb(u8 value, unsigned long addr);
+void logic_outw(u16 value, unsigned long addr);
+void logic_outl(u32 value, unsigned long addr);
+void logic_insb(unsigned long addr, void *buffer, unsigned int count);
+void logic_insl(unsigned long addr, void *buffer, unsigned int count);
+void logic_insw(unsigned long addr, void *buffer, unsigned int count);
+void logic_outsb(unsigned long addr, const void *buffer, unsigned int count);
+void logic_outsw(unsigned long addr, const void *buffer, unsigned int count);
+void logic_outsl(unsigned long addr, const void *buffer, unsigned int count);
+
+#ifndef inb
+#define inb logic_inb
+#endif
+
+#ifndef inw
+#define inw logic_inw
+#endif
+
+#ifndef inl
+#define inl logic_inl
+#endif
+
+#ifndef outb
+#define outb logic_outb
+#endif
+
+#ifndef outw
+#define outw logic_outw
+#endif
+
+#ifndef outl
+#define outl logic_outl
+#endif
+
+#ifndef insb
+#define insb logic_insb
+#endif
+
+#ifndef insw
+#define insw logic_insw
+#endif
+
+#ifndef insl
+#define insl logic_insl
+#endif
+
+#ifndef outsb
+#define outsb logic_outsb
+#endif
+
+#ifndef outsw
+#define outsw logic_outsw
+#endif
+
+#ifndef outsl
+#define outsl logic_outsl
+#endif
+
+/*
+ * We reserve 0x4000 bytes for Indirect IO as so far this library is only
+ * used by the HiSilicon LPC Host. If needed, we can reserve a wider IO
+ * area by redefining the macro below.
+ */
+#define PIO_INDIRECT_SIZE 0x4000
+#define MMIO_UPPER_LIMIT (IO_SPACE_LIMIT - PIO_INDIRECT_SIZE)
+#else
+#define MMIO_UPPER_LIMIT IO_SPACE_LIMIT
+#endif /* CONFIG_INDIRECT_PIO */
+
+struct logic_pio_hwaddr *find_io_range_by_fwnode(struct fwnode_handle *fwnode);
+unsigned long logic_pio_trans_hwaddr(struct fwnode_handle *fwnode,
+			resource_size_t hw_addr, resource_size_t size);
+int logic_pio_register_range(struct logic_pio_hwaddr *newrange);
+resource_size_t logic_pio_to_hwaddr(unsigned long pio);
+unsigned long logic_pio_trans_cpuaddr(resource_size_t hw_addr);
+
+#endif /* __LINUX_LOGIC_PIO_H */

lib/Kconfig

@@ -55,6 +55,22 @@ config ARCH_USE_CMPXCHG_LOCKREF
 config ARCH_HAS_FAST_MULTIPLIER
 	bool
 
+config INDIRECT_PIO
+	bool "Access I/O in non-MMIO mode"
+	depends on ARM64
+	help
+	  On some platforms where no separate I/O space exists, there are I/O
+	  hosts which can not be accessed in MMIO mode. Using the logical PIO
+	  mechanism, the host-local I/O resource can be mapped into system
+	  logic PIO space shared with MMIO hosts, such as PCI/PCIe, then the
+	  system can access the I/O devices with the mapped-logic PIO through
+	  I/O accessors.
+
+	  This way has relatively little I/O performance cost. Please make
+	  sure your devices really need this configure item enabled.
+
+	  When in doubt, say N.
+
 config CRC_CCITT
 	tristate "CRC-CCITT functions"
 	help

lib/Makefile

@@ -81,6 +81,8 @@ obj-$(CONFIG_HAS_IOMEM) += iomap_copy.o devres.o
 obj-$(CONFIG_CHECK_SIGNATURE) += check_signature.o
 obj-$(CONFIG_DEBUG_LOCKING_API_SELFTESTS) += locking-selftest.o
 
+obj-y += logic_pio.o
+
 obj-$(CONFIG_GENERIC_HWEIGHT) += hweight.o
 
 obj-$(CONFIG_BTREE) += btree.o