lib: Add generic PIO mapping method

41f8bba7f555 ("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 <dann.frazier@canonical.com>
Signed-off-by: Zhichang Yuan <yuanzhichang@hisilicon.com>
Signed-off-by: Gabriele Paoloni <gabriele.paoloni@huawei.com>
Signed-off-by: John Garry <john.garry@huawei.com>
[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/20180403211505.GA29612@embeddedor.com]
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>

5 files changed, 423 insertions, 0 deletions

diff --git a/include/asm-generic/io.h b/include/asm-generic/io.h
index b4531e3b2120..b7996a79d64b 100644
--- a/include/asm-generic/io.h
+++ b/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
diff --git a/include/linux/logic_pio.h b/include/linux/logic_pio.h
new file mode 100644
index 000000000000..cbd9d8495690
--- /dev/null
+++ b/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 <gabriele.paoloni@huawei.com>
+ * Author: Zhichang Yuan <yuanzhichang@hisilicon.com>
+ */
+
+#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 */
diff --git a/lib/Kconfig b/lib/Kconfig
index e96089499371..5fe577673b98 100644
--- a/lib/Kconfig
+++ b/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
diff --git a/lib/Makefile b/lib/Makefile
index a90d4fcd748f..4a9eacda3c8b 100644
--- a/lib/Makefile
+++ b/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
diff --git a/lib/logic_pio.c b/lib/logic_pio.c
new file mode 100644
index 000000000000..feea48fd1a0d
--- /dev/null
+++ b/lib/logic_pio.c
@@ -0,0 +1,280 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Copyright (C) 2017 HiSilicon Limited, All Rights Reserved.
+ * Author: Gabriele Paoloni <gabriele.paoloni@huawei.com>
+ * Author: Zhichang Yuan <yuanzhichang@hisilicon.com>
+ */
+
+#define pr_fmt(fmt)     "LOGIC PIO: " fmt
+
+#include <linux/of.h>
+#include <linux/io.h>
+#include <linux/logic_pio.h>
+#include <linux/mm.h>
+#include <linux/rculist.h>
+#include <linux/sizes.h>
+#include <linux/slab.h>
+
+/* The unique hardware address list */
+static LIST_HEAD(io_range_list);
+static DEFINE_MUTEX(io_range_mutex);
+
+/* Consider a kernel general helper for this */
+#define in_range(b, first, len)        ((b) >= (first) && (b) < (first) + (len))
+
+/**
+ * logic_pio_register_range - register logical PIO range for a host
+ * @new_range: pointer to the IO range to be registered.
+ *
+ * Returns 0 on success, the error code in case of failure.
+ *
+ * Register a new IO range node in the IO range list.
+ */
+int logic_pio_register_range(struct logic_pio_hwaddr *new_range)
+{
+        struct logic_pio_hwaddr *range;
+        resource_size_t start;
+        resource_size_t end;
+        resource_size_t mmio_sz = 0;
+        resource_size_t iio_sz = MMIO_UPPER_LIMIT;
+        int ret = 0;
+
+        if (!new_range || !new_range->fwnode || !new_range->size)
+                return -EINVAL;
+
+        start = new_range->hw_start;
+        end = new_range->hw_start + new_range->size;
+
+        mutex_lock(&io_range_mutex);
+        list_for_each_entry_rcu(range, &io_range_list, list) {
+                if (range->fwnode == new_range->fwnode) {
+                        /* range already there */
+                        goto end_register;
+                }
+                if (range->flags == LOGIC_PIO_CPU_MMIO &&
+                    new_range->flags == LOGIC_PIO_CPU_MMIO) {
+                        /* for MMIO ranges we need to check for overlap */
+                        if (start >= range->hw_start + range->size ||
+                            end < range->hw_start) {
+                                mmio_sz += range->size;
+                        } else {
+                                ret = -EFAULT;
+                                goto end_register;
+                        }
+                } else if (range->flags == LOGIC_PIO_INDIRECT &&
+                           new_range->flags == LOGIC_PIO_INDIRECT) {
+                        iio_sz += range->size;
+                }
+        }
+
+        /* range not registered yet, check for available space */
+        if (new_range->flags == LOGIC_PIO_CPU_MMIO) {
+                if (mmio_sz + new_range->size - 1 > MMIO_UPPER_LIMIT) {
+                        /* if it's too big check if 64K space can be reserved */
+                        if (mmio_sz + SZ_64K - 1 > MMIO_UPPER_LIMIT) {
+                                ret = -E2BIG;
+                                goto end_register;
+                        }
+                        new_range->size = SZ_64K;
+                        pr_warn("Requested IO range too big, new size set to 64K\n");
+                }
+                new_range->io_start = mmio_sz;
+        } else if (new_range->flags == LOGIC_PIO_INDIRECT) {
+                if (iio_sz + new_range->size - 1 > IO_SPACE_LIMIT) {
+                        ret = -E2BIG;
+                        goto end_register;
+                }
+                new_range->io_start = iio_sz;
+        } else {
+                /* invalid flag */
+                ret = -EINVAL;
+                goto end_register;
+        }
+
+        list_add_tail_rcu(&new_range->list, &io_range_list);
+
+end_register:
+        mutex_unlock(&io_range_mutex);
+        return ret;
+}
+
+/**
+ * find_io_range_by_fwnode - find logical PIO range for given FW node
+ * @fwnode: FW node handle associated with logical PIO range
+ *
+ * Returns pointer to node on success, NULL otherwise.
+ *
+ * Traverse the io_range_list to find the registered node for @fwnode.
+ */
+struct logic_pio_hwaddr *find_io_range_by_fwnode(struct fwnode_handle *fwnode)
+{
+        struct logic_pio_hwaddr *range;
+
+        list_for_each_entry_rcu(range, &io_range_list, list) {
+                if (range->fwnode == fwnode)
+                        return range;
+        }
+        return NULL;
+}
+
+/* Return a registered range given an input PIO token */
+static struct logic_pio_hwaddr *find_io_range(unsigned long pio)
+{
+        struct logic_pio_hwaddr *range;
+
+        list_for_each_entry_rcu(range, &io_range_list, list) {
+                if (in_range(pio, range->io_start, range->size))
+                        return range;
+        }
+        pr_err("PIO entry token %lx invalid\n", pio);
+        return NULL;
+}
+
+/**
+ * logic_pio_to_hwaddr - translate logical PIO to HW address
+ * @pio: logical PIO value
+ *
+ * Returns HW address if valid, ~0 otherwise.
+ *
+ * Translate the input logical PIO to the corresponding hardware address.
+ * The input PIO should be unique in the whole logical PIO space.
+ */
+resource_size_t logic_pio_to_hwaddr(unsigned long pio)
+{
+        struct logic_pio_hwaddr *range;
+
+        range = find_io_range(pio);
+        if (range)
+                return range->hw_start + pio - range->io_start;
+
+        return (resource_size_t)~0;
+}
+
+/**
+ * logic_pio_trans_hwaddr - translate HW address to logical PIO
+ * @fwnode: FW node reference for the host
+ * @addr: Host-relative HW address
+ * @size: size to translate
+ *
+ * Returns Logical PIO value if successful, ~0UL otherwise
+ */
+unsigned long logic_pio_trans_hwaddr(struct fwnode_handle *fwnode,
+                                     resource_size_t addr, resource_size_t size)
+{
+        struct logic_pio_hwaddr *range;
+
+        range = find_io_range_by_fwnode(fwnode);
+        if (!range || range->flags == LOGIC_PIO_CPU_MMIO) {
+                pr_err("IO range not found or invalid\n");
+                return ~0UL;
+        }
+        if (range->size < size) {
+                pr_err("resource size %pa cannot fit in IO range size %pa\n",
+                       &size, &range->size);
+                return ~0UL;
+        }
+        return addr - range->hw_start + range->io_start;
+}
+
+unsigned long logic_pio_trans_cpuaddr(resource_size_t addr)
+{
+        struct logic_pio_hwaddr *range;
+
+        list_for_each_entry_rcu(range, &io_range_list, list) {
+                if (range->flags != LOGIC_PIO_CPU_MMIO)
+                        continue;
+                if (in_range(addr, range->hw_start, range->size))
+                        return addr - range->hw_start + range->io_start;
+        }
+        pr_err("addr %llx not registered in io_range_list\n",
+               (unsigned long long) addr);
+        return ~0UL;
+}
+
+#if defined(CONFIG_INDIRECT_PIO) && defined(PCI_IOBASE)
+#define BUILD_LOGIC_IO(bw, type)                                        \
+type logic_in##bw(unsigned long addr)                                   \
+{                                                                       \
+        type ret = (type)~0;                                            \
+                                                                        \
+        if (addr < MMIO_UPPER_LIMIT) {                                  \
+                ret = read##bw(PCI_IOBASE + addr);                      \
+        } else if (addr >= MMIO_UPPER_LIMIT && addr < IO_SPACE_LIMIT) { \
+                struct logic_pio_hwaddr *entry = find_io_range(addr);   \
+                                                                        \
+                if (entry && entry->ops)                                \
+                        ret = entry->ops->in(entry->hostdata,           \
+                                        addr, sizeof(type));            \
+                else                                                    \
+                        WARN_ON_ONCE(1);                                \
+        }                                                               \
+        return ret;                                                     \
+}                                                                       \
+                                                                        \
+void logic_out##bw(type value, unsigned long addr)                      \
+{                                                                       \
+        if (addr < MMIO_UPPER_LIMIT) {                                  \
+                write##bw(value, PCI_IOBASE + addr);                    \
+        } else if (addr >= MMIO_UPPER_LIMIT && addr < IO_SPACE_LIMIT) { \
+                struct logic_pio_hwaddr *entry = find_io_range(addr);   \
+                                                                        \
+                if (entry && entry->ops)                                \
+                        entry->ops->out(entry->hostdata,                \
+                                        addr, value, sizeof(type));     \
+                else                                                    \
+                        WARN_ON_ONCE(1);                                \
+        }                                                               \
+}                                                                       \
+                                                                        \
+void logic_ins##bw(unsigned long addr, void *buffer,            \
+                   unsigned int count)                                  \
+{                                                                       \
+        if (addr < MMIO_UPPER_LIMIT) {                                  \
+                reads##bw(PCI_IOBASE + addr, buffer, count);            \
+        } else if (addr >= MMIO_UPPER_LIMIT && addr < IO_SPACE_LIMIT) { \
+                struct logic_pio_hwaddr *entry = find_io_range(addr);   \
+                                                                        \
+                if (entry && entry->ops)                                \
+                        entry->ops->ins(entry->hostdata,                \
+                                addr, buffer, sizeof(type), count);     \
+                else                                                    \
+                        WARN_ON_ONCE(1);                                \
+        }                                                               \
+                                                                        \
+}                                                                       \
+                                                                        \
+void logic_outs##bw(unsigned long addr, const void *buffer,             \
+                    unsigned int count)                                 \
+{                                                                       \
+        if (addr < MMIO_UPPER_LIMIT) {                                  \
+                writes##bw(PCI_IOBASE + addr, buffer, count);           \
+        } else if (addr >= MMIO_UPPER_LIMIT && addr < IO_SPACE_LIMIT) { \
+                struct logic_pio_hwaddr *entry = find_io_range(addr);   \
+                                                                        \
+                if (entry && entry->ops)                                \
+                        entry->ops->outs(entry->hostdata,               \
+                                addr, buffer, sizeof(type), count);     \
+                else                                                    \
+                        WARN_ON_ONCE(1);                                \
+        }                                                               \
+}
+
+BUILD_LOGIC_IO(b, u8)
+EXPORT_SYMBOL(logic_inb);
+EXPORT_SYMBOL(logic_insb);
+EXPORT_SYMBOL(logic_outb);
+EXPORT_SYMBOL(logic_outsb);
+
+BUILD_LOGIC_IO(w, u16)
+EXPORT_SYMBOL(logic_inw);
+EXPORT_SYMBOL(logic_insw);
+EXPORT_SYMBOL(logic_outw);
+EXPORT_SYMBOL(logic_outsw);
+
+BUILD_LOGIC_IO(l, u32)
+EXPORT_SYMBOL(logic_inl);
+EXPORT_SYMBOL(logic_insl);
+EXPORT_SYMBOL(logic_outl);
+EXPORT_SYMBOL(logic_outsl);
+
+#endif /* CONFIG_INDIRECT_PIO && PCI_IOBASE */