On 11/29/2010 02:41 PM, Wolfgang Grandegger wrote:
> Hello,
>
> I hit the send button too early, sorry...
>
> On 11/29/2010 02:23 PM, Wolfgang Grandegger wrote:
>> On 11/29/2010 11:24 AM, tiejun.chen wrote:
>>> Wolfgang Grandegger wrote:
>>>> Hello,
>>>>
>>>> I'm trying to read from mmapped PCI memory space on an alchemy board,
>>>> but I can't get it to work. Here's the lspci output of the PCI card:
>>>>
>>>> bash-3.00# lspci -v
>>>> 00:00.0 Class 0200: 168c:001b (rev 01)
>>>> Subsystem: 168c:2063
>>>> Flags: bus master, medium devsel, latency 168, IRQ 9
>>>> Memory at 0000000040000000 (32-bit, non-prefetchable) [size=64K]
>>>> Capabilities: [44] Power Management version 2
>>>>
>>>> I used mmap on "/dev/mem" and "/sys/bus/pci/.../resource0", but I do not
>>>> read the expected values using "*(volatile u32 *)mmap_addr" from that
>>>> region. The value also changes from read to read. Reading from kernel
>>>> space just work fine. Am I doing something illegal? Any idea why it does
>>>> not work?
>>>
>>> Form here I'm not sure how you did exactly.
>>>
>>> Theoretically, you can mmap() directly that at least from the sys resource. But
>>> I think you have to notice the aligning requirement for a page. I means you
>>> should firstly map one given base_address & ~(PAGE_SIZE - 1). Then access the
>>> last destination address with adding the corresponding offset as you want.
>
> I'm aware of the alignment issue. Anyway, I'm mapping the above address,
> which is already aligned. It must be something else. I'm using the
> ath_info and devmem2 Program for testing.
It's an issue with 64-bit address mapping. Currently mmap tries to map
0x4000'0000 but the physical address of the PCI memory space on my CPU is
0x4'4000'0000. I wonder why this problem has not yet been discovered.
The attached patch below works for my board.
Wolfgang.
>From 97fa0ab2beb1817785d017621ba2b6910006ed25 Mon Sep 17 00:00:00 2001
From: Wolfgang Grandegger <wg@xxxxxxx>
Date: Mon, 13 Dec 2010 21:29:09 +0100
Subject: [PATCH] mips/pci: use pci_resource_to_user to map pci memory space properly
Signed-off-by: Wolfgang Grandegger <wg@xxxxxxx>
---
arch/mips/include/asm/pci.h | 12 ++++++++++++
1 files changed, 12 insertions(+), 0 deletions(-)
diff --git a/arch/mips/include/asm/pci.h b/arch/mips/include/asm/pci.h
index 576397c..f38943b 100644
--- a/arch/mips/include/asm/pci.h
+++ b/arch/mips/include/asm/pci.h
@@ -82,6 +82,18 @@ static inline void pcibios_penalize_isa_irq(int irq, int active)
extern int pci_mmap_page_range(struct pci_dev *dev, struct vm_area_struct *vma,
enum pci_mmap_state mmap_state, int write_combine);
+#define HAVE_ARCH_PCI_RESOURCE_TO_USER
+
+static inline void pci_resource_to_user(const struct pci_dev *dev, int bar,
+ const struct resource *rsrc, resource_size_t *start,
+ resource_size_t *end)
+{
+ phys_t size = resource_size(rsrc);
+
+ *start = fixup_bigphys_addr(rsrc->start, size);
+ *end = rsrc->start + size;
+}
+
/*
* Dynamic DMA mapping stuff.
* MIPS has everything mapped statically.
--
1.7.2.3
