deleted file mode 100644
@@ -1,220 +0,0 @@
-==========================================================
-How to access I/O mapped memory from within device drivers
-==========================================================
-
-:Author: Linus
-
-.. warning::
-
- The virt_to_bus() and bus_to_virt() functions have been
- superseded by the functionality provided by the PCI DMA interface
- (see Documentation/core-api/dma-api-howto.rst). They continue
- to be documented below for historical purposes, but new code
- must not use them. --davidm 00/12/12
-
-::
-
- [ This is a mail message in response to a query on IO mapping, thus the
- strange format for a "document" ]
-
-The AHA-1542 is a bus-master device, and your patch makes the driver give the
-controller the physical address of the buffers, which is correct on x86
-(because all bus master devices see the physical memory mappings directly).
-
-However, on many setups, there are actually **three** different ways of looking
-at memory addresses, and in this case we actually want the third, the
-so-called "bus address".
-
-Essentially, the three ways of addressing memory are (this is "real memory",
-that is, normal RAM--see later about other details):
-
- - CPU untranslated. This is the "physical" address. Physical address
- 0 is what the CPU sees when it drives zeroes on the memory bus.
-
- - CPU translated address. This is the "virtual" address, and is
- completely internal to the CPU itself with the CPU doing the appropriate
- translations into "CPU untranslated".
-
- - bus address. This is the address of memory as seen by OTHER devices,
- not the CPU. Now, in theory there could be many different bus
- addresses, with each device seeing memory in some device-specific way, but
- happily most hardware designers aren't actually actively trying to make
- things any more complex than necessary, so you can assume that all
- external hardware sees the memory the same way.
-
-Now, on normal PCs the bus address is exactly the same as the physical
-address, and things are very simple indeed. However, they are that simple
-because the memory and the devices share the same address space, and that is
-not generally necessarily true on other PCI/ISA setups.
-
-Now, just as an example, on the PReP (PowerPC Reference Platform), the
-CPU sees a memory map something like this (this is from memory)::
-
- 0-2 GB "real memory"
- 2 GB-3 GB "system IO" (inb/out and similar accesses on x86)
- 3 GB-4 GB "IO memory" (shared memory over the IO bus)
-
-Now, that looks simple enough. However, when you look at the same thing from
-the viewpoint of the devices, you have the reverse, and the physical memory
-address 0 actually shows up as address 2 GB for any IO master.
-
-So when the CPU wants any bus master to write to physical memory 0, it
-has to give the master address 0x80000000 as the memory address.
-
-So, for example, depending on how the kernel is actually mapped on the
-PPC, you can end up with a setup like this::
-
- physical address: 0
- virtual address: 0xC0000000
- bus address: 0x80000000
-
-where all the addresses actually point to the same thing. It's just seen
-through different translations..
-
-Similarly, on the Alpha, the normal translation is::
-
- physical address: 0
- virtual address: 0xfffffc0000000000
- bus address: 0x40000000
-
-(but there are also Alphas where the physical address and the bus address
-are the same).
-
-Anyway, the way to look up all these translations, you do::
-
- #include <asm/io.h>
-
- phys_addr = virt_to_phys(virt_addr);
- virt_addr = phys_to_virt(phys_addr);
- bus_addr = virt_to_bus(virt_addr);
- virt_addr = bus_to_virt(bus_addr);
-
-Now, when do you need these?
-
-You want the **virtual** address when you are actually going to access that
-pointer from the kernel. So you can have something like this::
-
- /*
- * this is the hardware "mailbox" we use to communicate with
- * the controller. The controller sees this directly.
- */
- struct mailbox {
- __u32 status;
- __u32 bufstart;
- __u32 buflen;
- ..
- } mbox;
-
- unsigned char * retbuffer;
-
- /* get the address from the controller */
- retbuffer = bus_to_virt(mbox.bufstart);
- switch (retbuffer[0]) {
- case STATUS_OK:
- ...
-
-on the other hand, you want the bus address when you have a buffer that
-you want to give to the controller::
-
- /* ask the controller to read the sense status into "sense_buffer" */
- mbox.bufstart = virt_to_bus(&sense_buffer);
- mbox.buflen = sizeof(sense_buffer);
- mbox.status = 0;
- notify_controller(&mbox);
-
-And you generally **never** want to use the physical address, because you can't
-use that from the CPU (the CPU only uses translated virtual addresses), and
-you can't use it from the bus master.
-
-So why do we care about the physical address at all? We do need the physical
-address in some cases, it's just not very often in normal code. The physical
-address is needed if you use memory mappings, for example, because the
-"remap_pfn_range()" mm function wants the physical address of the memory to
-be remapped as measured in units of pages, a.k.a. the pfn (the memory
-management layer doesn't know about devices outside the CPU, so it
-shouldn't need to know about "bus addresses" etc).
-
-.. note::
-
- The above is only one part of the whole equation. The above
- only talks about "real memory", that is, CPU memory (RAM).
-
-There is a completely different type of memory too, and that's the "shared
-memory" on the PCI or ISA bus. That's generally not RAM (although in the case
-of a video graphics card it can be normal DRAM that is just used for a frame
-buffer), but can be things like a packet buffer in a network card etc.
-
-This memory is called "PCI memory" or "shared memory" or "IO memory" or
-whatever, and there is only one way to access it: the readb/writeb and
-related functions. You should never take the address of such memory, because
-there is really nothing you can do with such an address: it's not
-conceptually in the same memory space as "real memory" at all, so you cannot
-just dereference a pointer. (Sadly, on x86 it **is** in the same memory space,
-so on x86 it actually works to just deference a pointer, but it's not
-portable).
-
-For such memory, you can do things like:
-
- - reading::
-
- /*
- * read first 32 bits from ISA memory at 0xC0000, aka
- * C000:0000 in DOS terms
- */
- unsigned int signature = isa_readl(0xC0000);
-
- - remapping and writing::
-
- /*
- * remap framebuffer PCI memory area at 0xFC000000,
- * size 1MB, so that we can access it: We can directly
- * access only the 640k-1MB area, so anything else
- * has to be remapped.
- */
- void __iomem *baseptr = ioremap(0xFC000000, 1024*1024);
-
- /* write a 'A' to the offset 10 of the area */
- writeb('A',baseptr+10);
-
- /* unmap when we unload the driver */
- iounmap(baseptr);
-
- - copying and clearing::
-
- /* get the 6-byte Ethernet address at ISA address E000:0040 */
- memcpy_fromio(kernel_buffer, 0xE0040, 6);
- /* write a packet to the driver */
- memcpy_toio(0xE1000, skb->data, skb->len);
- /* clear the frame buffer */
- memset_io(0xA0000, 0, 0x10000);
-
-OK, that just about covers the basics of accessing IO portably. Questions?
-Comments? You may think that all the above is overly complex, but one day you
-might find yourself with a 500 MHz Alpha in front of you, and then you'll be
-happy that your driver works ;)
-
-Note that kernel versions 2.0.x (and earlier) mistakenly called the
-ioremap() function "vremap()". ioremap() is the proper name, but I
-didn't think straight when I wrote it originally. People who have to
-support both can do something like::
-
- /* support old naming silliness */
- #if LINUX_VERSION_CODE < 0x020100
- #define ioremap vremap
- #define iounmap vfree
- #endif
-
-at the top of their source files, and then they can use the right names
-even on 2.0.x systems.
-
-And the above sounds worse than it really is. Most real drivers really
-don't do all that complex things (or rather: the complexity is not so
-much in the actual IO accesses as in error handling and timeouts etc).
-It's generally not hard to fix drivers, and in many cases the code
-actually looks better afterwards::
-
- unsigned long signature = *(unsigned int *) 0xC0000;
- vs
- unsigned long signature = readl(0xC0000);
-
-I think the second version actually is more readable, no?
@@ -707,20 +707,6 @@ to use the dma_sync_*() interfaces::
}
}
-Drivers converted fully to this interface should not use virt_to_bus() any
-longer, nor should they use bus_to_virt(). Some drivers have to be changed a
-little bit, because there is no longer an equivalent to bus_to_virt() in the
-dynamic DMA mapping scheme - you have to always store the DMA addresses
-returned by the dma_alloc_coherent(), dma_pool_alloc(), and dma_map_single()
-calls (dma_map_sg() stores them in the scatterlist itself if the platform
-supports dynamic DMA mapping in hardware) in your driver structures and/or
-in the card registers.
-
-All drivers should be using these interfaces with no exceptions. It
-is planned to completely remove virt_to_bus() and bus_to_virt() as
-they are entirely deprecated. Some ports already do not provide these
-as it is impossible to correctly support them.
-
Handling Errors
===============
@@ -39,7 +39,6 @@ Library functionality that is used throughout the kernel.
rbtree
generic-radix-tree
packing
- bus-virt-phys-mapping
this_cpu_ops
timekeeping
errseq
@@ -52,7 +52,6 @@ Todolist:
circular-buffers
generic-radix-tree
packing
- bus-virt-phys-mapping
this_cpu_ops
timekeeping
errseq
@@ -17,7 +17,6 @@ config ALPHA
select HAVE_PERF_EVENTS
select NEED_DMA_MAP_STATE
select NEED_SG_DMA_LENGTH
- select VIRT_TO_BUS
select GENERIC_IRQ_PROBE
select GENERIC_PCI_IOMAP
select AUTO_IRQ_AFFINITY if SMP
@@ -20,7 +20,7 @@
#define fd_free_dma() free_dma(FLOPPY_DMA)
#define fd_clear_dma_ff() clear_dma_ff(FLOPPY_DMA)
#define fd_set_dma_mode(mode) set_dma_mode(FLOPPY_DMA,mode)
-#define fd_set_dma_addr(addr) set_dma_addr(FLOPPY_DMA,virt_to_bus(addr))
+#define fd_set_dma_addr(addr) set_dma_addr(FLOPPY_DMA,isa_virt_to_bus(addr))
#define fd_set_dma_count(count) set_dma_count(FLOPPY_DMA,count)
#define fd_enable_irq() enable_irq(FLOPPY_IRQ)
#define fd_disable_irq() disable_irq(FLOPPY_IRQ)
@@ -106,15 +106,15 @@ static inline void * phys_to_virt(unsigned long address)
extern unsigned long __direct_map_base;
extern unsigned long __direct_map_size;
-static inline unsigned long __deprecated virt_to_bus(volatile void *address)
+static inline unsigned long __deprecated isa_virt_to_bus(volatile void *address)
{
unsigned long phys = virt_to_phys(address);
unsigned long bus = phys + __direct_map_base;
return phys <= __direct_map_size ? bus : 0;
}
-#define isa_virt_to_bus virt_to_bus
+#define isa_virt_to_bus isa_virt_to_bus
-static inline void * __deprecated bus_to_virt(unsigned long address)
+static inline void * __deprecated isa_bus_to_virt(unsigned long address)
{
void *virt;
@@ -125,7 +125,7 @@ static inline void * __deprecated bus_to_virt(unsigned long address)
virt = phys_to_virt(address);
return (long)address <= 0 ? NULL : virt;
}
-#define isa_bus_to_virt bus_to_virt
+#define isa_bus_to_virt isa_bus_to_virt
/*
* There are different chipsets to interface the Alpha CPUs to the world.
@@ -39,7 +39,6 @@ config IA64
select HAVE_FUNCTION_DESCRIPTORS
select HAVE_VIRT_CPU_ACCOUNTING
select HUGETLB_PAGE_SIZE_VARIABLE if HUGETLB_PAGE
- select VIRT_TO_BUS
select GENERIC_IRQ_PROBE
select GENERIC_PENDING_IRQ if SMP
select GENERIC_IRQ_SHOW
@@ -96,14 +96,6 @@ extern u64 kern_mem_attribute (unsigned long phys_addr, unsigned long size);
extern int valid_phys_addr_range (phys_addr_t addr, size_t count); /* efi.c */
extern int valid_mmap_phys_addr_range (unsigned long pfn, size_t count);
-/*
- * The following two macros are deprecated and scheduled for removal.
- * Please use the PCI-DMA interface defined in <asm/pci.h> instead.
- */
-#define bus_to_virt phys_to_virt
-#define virt_to_bus virt_to_phys
-#define page_to_bus page_to_phys
-
# endif /* KERNEL */
/*
@@ -30,7 +30,6 @@ config M68K
select OLD_SIGACTION
select OLD_SIGSUSPEND3
select UACCESS_MEMCPY if !MMU
- select VIRT_TO_BUS
select ZONE_DMA
config CPU_BIG_ENDIAN
@@ -33,9 +33,11 @@ static inline void *phys_to_virt(unsigned long address)
/*
* IO bus memory addresses are 1:1 with the physical address,
+ * deprecated globally but still used on two machines.
*/
+#if defined(CONFIG_AMIGA) || defined(CONFIG_VME)
#define virt_to_bus virt_to_phys
-#define bus_to_virt phys_to_virt
+#endif
#endif
#endif
@@ -38,7 +38,6 @@ config MICROBLAZE
select OF_EARLY_FLATTREE
select PCI_DOMAINS_GENERIC if PCI
select PCI_SYSCALL if PCI
- select VIRT_TO_BUS
select CPU_NO_EFFICIENT_FFS
select MMU_GATHER_NO_RANGE
select SPARSE_IRQ
@@ -30,8 +30,6 @@ extern resource_size_t isa_mem_base;
#define PCI_IOBASE ((void __iomem *)_IO_BASE)
#define IO_SPACE_LIMIT (0xFFFFFFFF)
-#define page_to_bus(page) (page_to_phys(page))
-
extern void iounmap(volatile void __iomem *addr);
extern void __iomem *ioremap(phys_addr_t address, unsigned long size);
@@ -100,7 +100,6 @@ config MIPS
select RTC_LIB
select SYSCTL_EXCEPTION_TRACE
select TRACE_IRQFLAGS_SUPPORT
- select VIRT_TO_BUS
select ARCH_HAS_ELFCORE_COMPAT
select HAVE_ARCH_KCSAN if 64BIT
@@ -147,15 +147,6 @@ static inline void *isa_bus_to_virt(unsigned long address)
return phys_to_virt(address);
}
-/*
- * However PCI ones are not necessarily 1:1 and therefore these interfaces
- * are forbidden in portable PCI drivers.
- *
- * Allow them for x86 for legacy drivers, though.
- */
-#define virt_to_bus virt_to_phys
-#define bus_to_virt phys_to_virt
-
/*
* Change "struct page" to physical address.
*/
@@ -43,7 +43,6 @@ config PARISC
select SYSCTL_ARCH_UNALIGN_ALLOW
select SYSCTL_EXCEPTION_TRACE
select HAVE_MOD_ARCH_SPECIFIC
- select VIRT_TO_BUS
select MODULES_USE_ELF_RELA
select CLONE_BACKWARDS
select TTY # Needed for pdc_cons.c
@@ -179,7 +179,7 @@ static void _fd_chose_dma_mode(char *addr, unsigned long size)
{
if(can_use_virtual_dma == 2) {
if((unsigned int) addr >= (unsigned int) high_memory ||
- virt_to_bus(addr) >= 0x1000000 ||
+ virt_to_phys(addr) >= 0x1000000 ||
_CROSS_64KB(addr, size, 0))
use_virtual_dma = 1;
else
@@ -215,7 +215,7 @@ static int hard_dma_setup(char *addr, unsigned long size, int mode, int io)
doing_pdma = 0;
clear_dma_ff(FLOPPY_DMA);
set_dma_mode(FLOPPY_DMA,mode);
- set_dma_addr(FLOPPY_DMA,virt_to_bus(addr));
+ set_dma_addr(FLOPPY_DMA,virt_to_phys(addr));
set_dma_count(FLOPPY_DMA,size);
enable_dma(FLOPPY_DMA);
return 0;
@@ -7,8 +7,6 @@
#define virt_to_phys(a) ((unsigned long)__pa(a))
#define phys_to_virt(a) __va(a)
-#define virt_to_bus virt_to_phys
-#define bus_to_virt phys_to_virt
static inline unsigned long isa_bus_to_virt(unsigned long addr) {
BUG();
@@ -272,7 +272,6 @@ config PPC
select SYSCTL_EXCEPTION_TRACE
select THREAD_INFO_IN_TASK
select TRACE_IRQFLAGS_SUPPORT
- select VIRT_TO_BUS if !PPC64
#
# Please keep this list sorted alphabetically.
#
@@ -987,8 +987,6 @@ static inline void * bus_to_virt(unsigned long address)
}
#define bus_to_virt bus_to_virt
-#define page_to_bus(page) (page_to_phys(page) + PCI_DRAM_OFFSET)
-
#endif /* CONFIG_PPC32 */
/* access ports */
@@ -167,7 +167,6 @@ extern phys_addr_t __phys_addr_symbol(unsigned long x);
#define page_to_virt(page) (pfn_to_virt(page_to_pfn(page)))
#define page_to_phys(page) (pfn_to_phys(page_to_pfn(page)))
-#define page_to_bus(page) (page_to_phys(page))
#define phys_to_page(paddr) (pfn_to_page(phys_to_pfn(paddr)))
#define sym_to_pfn(x) __phys_to_pfn(__pa_symbol(x))
@@ -273,7 +273,6 @@ config X86
select THREAD_INFO_IN_TASK
select TRACE_IRQFLAGS_SUPPORT
select USER_STACKTRACE_SUPPORT
- select VIRT_TO_BUS
select HAVE_ARCH_KCSAN if X86_64
select X86_FEATURE_NAMES if PROC_FS
select PROC_PID_ARCH_STATUS if PROC_FS
@@ -168,15 +168,6 @@ static inline unsigned int isa_virt_to_bus(volatile void *address)
}
#define isa_bus_to_virt phys_to_virt
-/*
- * However PCI ones are not necessarily 1:1 and therefore these interfaces
- * are forbidden in portable PCI drivers.
- *
- * Allow them on x86 for legacy drivers, though.
- */
-#define virt_to_bus virt_to_phys
-#define bus_to_virt phys_to_virt
-
/*
* The default ioremap() behavior is non-cached; if you need something
* else, you probably want one of the following.
@@ -46,7 +46,6 @@ config XTENSA
select MODULES_USE_ELF_RELA
select PERF_USE_VMALLOC
select TRACE_IRQFLAGS_SUPPORT
- select VIRT_TO_BUS
help
Xtensa processors are 32-bit RISC machines designed by Tensilica
primarily for embedded systems. These processors are both
@@ -63,9 +63,6 @@ static inline void iounmap(volatile void __iomem *addr)
xtensa_iounmap(addr);
}
-#define virt_to_bus virt_to_phys
-#define bus_to_virt phys_to_virt
-
#endif /* CONFIG_MMU */
#include <asm-generic/io.h>
@@ -1059,20 +1059,6 @@ static inline void unxlate_dev_mem_ptr(phys_addr_t phys, void *addr)
}
#endif
-#ifdef CONFIG_VIRT_TO_BUS
-#ifndef virt_to_bus
-static inline unsigned long virt_to_bus(void *address)
-{
- return (unsigned long)address;
-}
-
-static inline void *bus_to_virt(unsigned long address)
-{
- return (void *)address;
-}
-#endif
-#endif
-
#ifndef memset_io
#define memset_io memset_io
/**
@@ -283,14 +283,6 @@ config BOUNCE
memory available to the CPU. Enabled by default when HIGHMEM is
selected, but you may say n to override this.
-config VIRT_TO_BUS
- bool
- help
- An architecture should select this if it implements the
- deprecated interface virt_to_bus(). All new architectures
- should probably not select this.
-
-
config MMU_NOTIFIER
bool
select SRCU