lib: add iomem emulation (logic_iomem)
authorJohannes Berg <johannes.berg@intel.com>
Fri, 5 Mar 2021 12:19:52 +0000 (13:19 +0100)
committerRichard Weinberger <richard@nod.at>
Thu, 17 Jun 2021 19:44:51 +0000 (21:44 +0200)
Add IO memory emulation that uses callbacks for read/write to
the allocated regions. The callbacks can be registered by the
users using logic_iomem_alloc().

To use, an architecture must 'select LOGIC_IOMEM' in Kconfig
and then include <asm-generic/logic_io.h> into asm/io.h to get
the __raw_read*/__raw_write* functions.

Optionally, an architecture may 'select LOGIC_IOMEM_FALLBACK'
in which case non-emulated regions will 'fall back' to the
various real_* functions that must then be provided.

Cc: Arnd Bergmann <arnd@kernel.org>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Richard Weinberger <richard@nod.at>
include/asm-generic/logic_io.h [new file with mode: 0644]
include/linux/logic_iomem.h [new file with mode: 0644]
lib/Kconfig
lib/Makefile
lib/logic_iomem.c [new file with mode: 0644]

diff --git a/include/asm-generic/logic_io.h b/include/asm-generic/logic_io.h
new file mode 100644 (file)
index 0000000..a53116b
--- /dev/null
@@ -0,0 +1,78 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Copyright (C) 2021 Intel Corporation
+ * Author: johannes@sipsolutions.net
+ */
+#ifndef _LOGIC_IO_H
+#define _LOGIC_IO_H
+#include <linux/types.h>
+
+/* include this file into asm/io.h */
+
+#ifdef CONFIG_INDIRECT_IOMEM
+
+#ifdef CONFIG_INDIRECT_IOMEM_FALLBACK
+/*
+ * If you want emulated IO memory to fall back to 'normal' IO memory
+ * if a region wasn't registered as emulated, then you need to have
+ * all of the real_* functions implemented.
+ */
+#if !defined(real_ioremap) || !defined(real_iounmap) || \
+    !defined(real_raw_readb) || !defined(real_raw_writeb) || \
+    !defined(real_raw_readw) || !defined(real_raw_writew) || \
+    !defined(real_raw_readl) || !defined(real_raw_writel) || \
+    (defined(CONFIG_64BIT) && \
+     (!defined(real_raw_readq) || !defined(real_raw_writeq))) || \
+    !defined(real_memset_io) || \
+    !defined(real_memcpy_fromio) || \
+    !defined(real_memcpy_toio)
+#error "Must provide fallbacks for real IO memory access"
+#endif /* defined ... */
+#endif /* CONFIG_INDIRECT_IOMEM_FALLBACK */
+
+#define ioremap ioremap
+void __iomem *ioremap(phys_addr_t offset, size_t size);
+
+#define iounmap iounmap
+void iounmap(void __iomem *addr);
+
+#define __raw_readb __raw_readb
+u8 __raw_readb(const volatile void __iomem *addr);
+
+#define __raw_readw __raw_readw
+u16 __raw_readw(const volatile void __iomem *addr);
+
+#define __raw_readl __raw_readl
+u32 __raw_readl(const volatile void __iomem *addr);
+
+#ifdef CONFIG_64BIT
+#define __raw_readq __raw_readq
+u64 __raw_readq(const volatile void __iomem *addr);
+#endif /* CONFIG_64BIT */
+
+#define __raw_writeb __raw_writeb
+void __raw_writeb(u8 value, volatile void __iomem *addr);
+
+#define __raw_writew __raw_writew
+void __raw_writew(u16 value, volatile void __iomem *addr);
+
+#define __raw_writel __raw_writel
+void __raw_writel(u32 value, volatile void __iomem *addr);
+
+#ifdef CONFIG_64BIT
+#define __raw_writeq __raw_writeq
+void __raw_writeq(u64 value, volatile void __iomem *addr);
+#endif /* CONFIG_64BIT */
+
+#define memset_io memset_io
+void memset_io(volatile void __iomem *addr, int value, size_t size);
+
+#define memcpy_fromio memcpy_fromio
+void memcpy_fromio(void *buffer, const volatile void __iomem *addr,
+                  size_t size);
+
+#define memcpy_toio memcpy_toio
+void memcpy_toio(volatile void __iomem *addr, const void *buffer, size_t size);
+
+#endif /* CONFIG_INDIRECT_IOMEM */
+#endif /* _LOGIC_IO_H */
diff --git a/include/linux/logic_iomem.h b/include/linux/logic_iomem.h
new file mode 100644 (file)
index 0000000..3fa65c9
--- /dev/null
@@ -0,0 +1,62 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Copyright (C) 2021 Intel Corporation
+ * Author: johannes@sipsolutions.net
+ */
+#ifndef __LOGIC_IOMEM_H
+#define __LOGIC_IOMEM_H
+#include <linux/types.h>
+#include <linux/ioport.h>
+
+/**
+ * struct logic_iomem_ops - emulated IO memory ops
+ * @read: read an 8, 16, 32 or 64 bit quantity from the given offset,
+ *     size is given in bytes (1, 2, 4 or 8)
+ *     (64-bit only necessary if CONFIG_64BIT is set)
+ * @write: write an 8, 16 32 or 64 bit quantity to the given offset,
+ *     size is given in bytes (1, 2, 4 or 8)
+ *     (64-bit only necessary if CONFIG_64BIT is set)
+ * @set: optional, for memset_io()
+ * @copy_from: optional, for memcpy_fromio()
+ * @copy_to: optional, for memcpy_toio()
+ * @unmap: optional, this region is getting unmapped
+ */
+struct logic_iomem_ops {
+       unsigned long (*read)(void *priv, unsigned int offset, int size);
+       void (*write)(void *priv, unsigned int offset, int size,
+                     unsigned long val);
+
+       void (*set)(void *priv, unsigned int offset, u8 value, int size);
+       void (*copy_from)(void *priv, void *buffer, unsigned int offset,
+                         int size);
+       void (*copy_to)(void *priv, unsigned int offset, const void *buffer,
+                       int size);
+
+       void (*unmap)(void *priv);
+};
+
+/**
+ * struct logic_iomem_region_ops - ops for an IO memory handler
+ * @map: map a range in the registered IO memory region, must
+ *     fill *ops with the ops and may fill *priv to be passed
+ *     to the ops. The offset is given as the offset into the
+ *     registered resource region.
+ *     The return value is negative for errors, or >= 0 for
+ *     success. On success, the return value is added to the
+ *     offset for later ops, to allow for partial mappings.
+ */
+struct logic_iomem_region_ops {
+       long (*map)(unsigned long offset, size_t size,
+                   const struct logic_iomem_ops **ops,
+                   void **priv);
+};
+
+/**
+ * logic_iomem_add_region - register an IO memory region
+ * @resource: the resource description for this region
+ * @ops: the IO memory mapping ops for this resource
+ */
+int logic_iomem_add_region(struct resource *resource,
+                          const struct logic_iomem_region_ops *ops);
+
+#endif /* __LOGIC_IOMEM_H */
index ac3b306..d241fe4 100644 (file)
@@ -102,6 +102,20 @@ config INDIRECT_PIO
 
          When in doubt, say N.
 
+config INDIRECT_IOMEM
+       bool
+       help
+         This is selected by other options/architectures to provide the
+         emulated iomem accessors.
+
+config INDIRECT_IOMEM_FALLBACK
+       bool
+       depends on INDIRECT_IOMEM
+       help
+         If INDIRECT_IOMEM is selected, this enables falling back to plain
+         mmio accesses when the IO memory address is not a registered
+         emulated region.
+
 config CRC_CCITT
        tristate "CRC-CCITT functions"
        help
index 2cc359e..fc38a55 100644 (file)
@@ -147,6 +147,8 @@ obj-$(CONFIG_DEBUG_LOCKING_API_SELFTESTS) += locking-selftest.o
 
 lib-y += logic_pio.o
 
+lib-$(CONFIG_INDIRECT_IOMEM) += logic_iomem.o
+
 obj-$(CONFIG_GENERIC_HWEIGHT) += hweight.o
 
 obj-$(CONFIG_BTREE) += btree.o
diff --git a/lib/logic_iomem.c b/lib/logic_iomem.c
new file mode 100644 (file)
index 0000000..b76b92d
--- /dev/null
@@ -0,0 +1,318 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2021 Intel Corporation
+ * Author: Johannes Berg <johannes@sipsolutions.net>
+ */
+#include <linux/types.h>
+#include <linux/slab.h>
+#include <linux/logic_iomem.h>
+
+struct logic_iomem_region {
+       const struct resource *res;
+       const struct logic_iomem_region_ops *ops;
+       struct list_head list;
+};
+
+struct logic_iomem_area {
+       const struct logic_iomem_ops *ops;
+       void *priv;
+};
+
+#define AREA_SHIFT     24
+#define MAX_AREA_SIZE  (1 << AREA_SHIFT)
+#define MAX_AREAS      ((1ULL<<32) / MAX_AREA_SIZE)
+#define AREA_BITS      ((MAX_AREAS - 1) << AREA_SHIFT)
+#define AREA_MASK      (MAX_AREA_SIZE - 1)
+#ifdef CONFIG_64BIT
+#define IOREMAP_BIAS   0xDEAD000000000000UL
+#define IOREMAP_MASK   0xFFFFFFFF00000000UL
+#else
+#define IOREMAP_BIAS   0
+#define IOREMAP_MASK   0
+#endif
+
+static DEFINE_MUTEX(regions_mtx);
+static LIST_HEAD(regions_list);
+static struct logic_iomem_area mapped_areas[MAX_AREAS];
+
+int logic_iomem_add_region(struct resource *resource,
+                          const struct logic_iomem_region_ops *ops)
+{
+       struct logic_iomem_region *rreg;
+       int err;
+
+       if (WARN_ON(!resource || !ops))
+               return -EINVAL;
+
+       if (WARN_ON((resource->flags & IORESOURCE_TYPE_BITS) != IORESOURCE_MEM))
+               return -EINVAL;
+
+       rreg = kzalloc(sizeof(*rreg), GFP_KERNEL);
+       if (!rreg)
+               return -ENOMEM;
+
+       err = request_resource(&iomem_resource, resource);
+       if (err) {
+               kfree(rreg);
+               return -ENOMEM;
+       }
+
+       mutex_lock(&regions_mtx);
+       rreg->res = resource;
+       rreg->ops = ops;
+       list_add_tail(&rreg->list, &regions_list);
+       mutex_unlock(&regions_mtx);
+
+       return 0;
+}
+EXPORT_SYMBOL(logic_iomem_add_region);
+
+#ifndef CONFIG_LOGIC_IOMEM_FALLBACK
+static void __iomem *real_ioremap(phys_addr_t offset, size_t size)
+{
+       WARN(1, "invalid ioremap(0x%llx, 0x%zx)\n",
+            (unsigned long long)offset, size);
+       return NULL;
+}
+
+static void real_iounmap(void __iomem *addr)
+{
+       WARN(1, "invalid iounmap for addr 0x%llx\n",
+            (unsigned long long)addr);
+}
+#endif /* CONFIG_LOGIC_IOMEM_FALLBACK */
+
+void __iomem *ioremap(phys_addr_t offset, size_t size)
+{
+       void __iomem *ret = NULL;
+       struct logic_iomem_region *rreg, *found = NULL;
+       int i;
+
+       mutex_lock(&regions_mtx);
+       list_for_each_entry(rreg, &regions_list, list) {
+               if (rreg->res->start > offset)
+                       continue;
+               if (rreg->res->end < offset + size - 1)
+                       continue;
+               found = rreg;
+               break;
+       }
+
+       if (!found)
+               goto out;
+
+       for (i = 0; i < MAX_AREAS; i++) {
+               long offs;
+
+               if (mapped_areas[i].ops)
+                       continue;
+
+               offs = rreg->ops->map(offset - found->res->start,
+                                     size, &mapped_areas[i].ops,
+                                     &mapped_areas[i].priv);
+               if (offs < 0) {
+                       mapped_areas[i].ops = NULL;
+                       break;
+               }
+
+               if (WARN_ON(!mapped_areas[i].ops)) {
+                       mapped_areas[i].ops = NULL;
+                       break;
+               }
+
+               ret = (void __iomem *)(IOREMAP_BIAS + (i << AREA_SHIFT) + offs);
+               break;
+       }
+out:
+       mutex_unlock(&regions_mtx);
+       if (ret)
+               return ret;
+       return real_ioremap(offset, size);
+}
+EXPORT_SYMBOL(ioremap);
+
+static inline struct logic_iomem_area *
+get_area(const volatile void __iomem *addr)
+{
+       unsigned long a = (unsigned long)addr;
+       unsigned int idx;
+
+       if (WARN_ON((a & IOREMAP_MASK) != IOREMAP_BIAS))
+               return NULL;
+
+       idx = (a & AREA_BITS) >> AREA_SHIFT;
+
+       if (mapped_areas[idx].ops)
+               return &mapped_areas[idx];
+
+       return NULL;
+}
+
+void iounmap(void __iomem *addr)
+{
+       struct logic_iomem_area *area = get_area(addr);
+
+       if (!area) {
+               real_iounmap(addr);
+               return;
+       }
+
+       if (area->ops->unmap)
+               area->ops->unmap(area->priv);
+
+       mutex_lock(&regions_mtx);
+       area->ops = NULL;
+       area->priv = NULL;
+       mutex_unlock(&regions_mtx);
+}
+EXPORT_SYMBOL(iounmap);
+
+#ifndef CONFIG_LOGIC_IOMEM_FALLBACK
+#define MAKE_FALLBACK(op, sz)                                          \
+static u##sz real_raw_read ## op(const volatile void __iomem *addr)    \
+{                                                                      \
+       WARN(1, "Invalid read" #op " at address %llx\n",                \
+            (unsigned long long)addr);                                 \
+       return (u ## sz)~0ULL;                                          \
+}                                                                      \
+                                                                       \
+void real_raw_write ## op(u ## sz val, volatile void __iomem *addr)    \
+{                                                                      \
+       WARN(1, "Invalid writeq" #op " of 0x%llx at address %llx\n",    \
+            (unsigned long long)val, (unsigned long long)addr);        \
+}                                                                      \
+
+MAKE_FALLBACK(b, 8);
+MAKE_FALLBACK(w, 16);
+MAKE_FALLBACK(l, 32);
+#ifdef CONFIG_64BIT
+MAKE_FALLBACK(q, 64);
+#endif
+
+static void real_memset_io(volatile void __iomem *addr, int value, size_t size)
+{
+       WARN(1, "Invalid memset_io at address 0x%llx\n",
+            (unsigned long long)addr);
+}
+
+static void real_memcpy_fromio(void *buffer, const volatile void __iomem *addr,
+                              size_t size)
+{
+       WARN(1, "Invalid memcpy_fromio at address 0x%llx\n",
+            (unsigned long long)addr);
+
+       memset(buffer, 0xff, size);
+}
+
+static void real_memcpy_toio(volatile void __iomem *addr, const void *buffer,
+                            size_t size)
+{
+       WARN(1, "Invalid memcpy_toio at address 0x%llx\n",
+            (unsigned long long)addr);
+}
+#endif /* CONFIG_LOGIC_IOMEM_FALLBACK */
+
+#define MAKE_OP(op, sz)                                                \
+u##sz __raw_read ## op(const volatile void __iomem *addr)              \
+{                                                                      \
+       struct logic_iomem_area *area = get_area(addr);                 \
+                                                                       \
+       if (!area)                                                      \
+               return real_raw_read ## op(addr);                       \
+                                                                       \
+       return (u ## sz) area->ops->read(area->priv,                    \
+                                        (unsigned long)addr & AREA_MASK,\
+                                        sz / 8);                       \
+}                                                                      \
+EXPORT_SYMBOL(__raw_read ## op);                                       \
+                                                                       \
+void __raw_write ## op(u ## sz val, volatile void __iomem *addr)       \
+{                                                                      \
+       struct logic_iomem_area *area = get_area(addr);                 \
+                                                                       \
+       if (!area) {                                                    \
+               real_raw_write ## op(val, addr);                        \
+               return;                                                 \
+       }                                                               \
+                                                                       \
+       area->ops->write(area->priv,                                    \
+                        (unsigned long)addr & AREA_MASK,               \
+                        sz / 8, val);                                  \
+}                                                                      \
+EXPORT_SYMBOL(__raw_write ## op)
+
+MAKE_OP(b, 8);
+MAKE_OP(w, 16);
+MAKE_OP(l, 32);
+#ifdef CONFIG_64BIT
+MAKE_OP(q, 64);
+#endif
+
+void memset_io(volatile void __iomem *addr, int value, size_t size)
+{
+       struct logic_iomem_area *area = get_area(addr);
+       unsigned long offs, start;
+
+       if (!area) {
+               real_memset_io(addr, value, size);
+               return;
+       }
+
+       start = (unsigned long)addr & AREA_MASK;
+
+       if (area->ops->set) {
+               area->ops->set(area->priv, start, value, size);
+               return;
+       }
+
+       for (offs = 0; offs < size; offs++)
+               area->ops->write(area->priv, start + offs, 1, value);
+}
+EXPORT_SYMBOL(memset_io);
+
+void memcpy_fromio(void *buffer, const volatile void __iomem *addr,
+                   size_t size)
+{
+       struct logic_iomem_area *area = get_area(addr);
+       u8 *buf = buffer;
+       unsigned long offs, start;
+
+       if (!area) {
+               real_memcpy_fromio(buffer, addr, size);
+               return;
+       }
+
+       start = (unsigned long)addr & AREA_MASK;
+
+       if (area->ops->copy_from) {
+               area->ops->copy_from(area->priv, buffer, start, size);
+               return;
+       }
+
+       for (offs = 0; offs < size; offs++)
+               buf[offs] = area->ops->read(area->priv, start + offs, 1);
+}
+EXPORT_SYMBOL(memcpy_fromio);
+
+void memcpy_toio(volatile void __iomem *addr, const void *buffer, size_t size)
+{
+       struct logic_iomem_area *area = get_area(addr);
+       const u8 *buf = buffer;
+       unsigned long offs, start;
+
+       if (!area) {
+               real_memcpy_toio(addr, buffer, size);
+               return;
+       }
+
+       start = (unsigned long)addr & AREA_MASK;
+
+       if (area->ops->copy_to) {
+               area->ops->copy_to(area->priv, start, buffer, size);
+               return;
+       }
+
+       for (offs = 0; offs < size; offs++)
+               area->ops->write(area->priv, start + offs, 1, buf[offs]);
+}
+EXPORT_SYMBOL(memcpy_toio);