Mirrors/u-boot
2
0
Fork 0
mirror of https://github.com/AsahiLinux/u-boot synced 2024-11-29 08:01:08 +00:00
Code Issues Projects Releases Packages Wiki Activity

ahci: Use virt_to_phys() to denote physical addresses for DMA

Browse source 
Update the assignment of various physical memory buffers used by the
SATA controller to explicitly be denoted as physical addresses.

The memory is identity-mapped, so these function calls are a nop, but
they provide good semantic documentation for any maintainers.

The return value of virt_to_phys() is 'unsigned long'.  On machines
where sizeof(unsigned long) != sizeof(pointer), a cast through
(uintptr_t) is needed to appease the compiler due to the potential of
losing the upper 32 bits of the address.

In compilation this scenario, a physical address could be 64-bits, yet
the C pointer environment only allows 32-bit addresses; the constraint
is that pointers cannot address more than 4Gb of memory and if
virt_to_phys() ever returns an out-of-range value for the physical
address, there are issues with emmory mapping which must be solved.
However, since the memory is identify mappeed, there is no problem
introducing the cast: the original pointer will reside in 32-bits, so
the physical address will also be within in 32-bits.

Signed-off-by: Taylor Hutt <thutt@chromium.org>
Signed-off-by: Simon Glass <sjg@chromium.org>
This commit is contained in:
Taylor Hutt 2012-10-29 05:23:58 +00:00 committed by Tom Rini
parent b4c5bbce49
commit 64738e8ae8
1 changed files with 6 additions and 4 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

10
drivers/block/ahci.c
View file

@ -431,25 +431,27 @@ static int ahci_port_start(u8 port)
* First item in chunk of DMA memory: 32-slot command table, * First item in chunk of DMA memory: 32-slot command table,
* 32 bytes each in size * 32 bytes each in size
*/ */
pp->cmd_slot = (struct ahci_cmd_hdr *)mem; pp->cmd_slot =
(struct ahci_cmd_hdr *)(uintptr_t)virt_to_phys((void *)mem);
debug("cmd_slot = 0x%x\n", (unsigned)pp->cmd_slot); debug("cmd_slot = 0x%x\n", (unsigned)pp->cmd_slot);
mem += (AHCI_CMD_SLOT_SZ + 224); mem += (AHCI_CMD_SLOT_SZ + 224);
/* /*
* Second item: Received-FIS area * Second item: Received-FIS area
*/ */
pp->rx_fis = mem; pp->rx_fis = virt_to_phys((void *)mem);
mem += AHCI_RX_FIS_SZ; mem += AHCI_RX_FIS_SZ;
/* /*
* Third item: data area for storing a single command * Third item: data area for storing a single command
* and its scatter-gather table * and its scatter-gather table
*/ */
pp->cmd_tbl = mem; pp->cmd_tbl = virt_to_phys((void *)mem);
debug("cmd_tbl_dma = 0x%x\n", pp->cmd_tbl); debug("cmd_tbl_dma = 0x%x\n", pp->cmd_tbl);
mem += AHCI_CMD_TBL_HDR; mem += AHCI_CMD_TBL_HDR;
pp->cmd_tbl_sg = (struct ahci_sg *)mem; pp->cmd_tbl_sg =
(struct ahci_sg *)(uintptr_t)virt_to_phys((void *)mem);
writel_with_flush((u32) pp->cmd_slot, port_mmio + PORT_LST_ADDR); writel_with_flush((u32) pp->cmd_slot, port_mmio + PORT_LST_ADDR);