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>

3 files changed, 298 insertions, 0 deletions

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 */