Commit 64738e8a authored by Taylor Hutt's avatar Taylor Hutt Committed by Tom Rini
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ahci: Use virt_to_phys() to denote physical addresses for DMA

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: default avatarTaylor Hutt <>
Signed-off-by: default avatarSimon Glass <>
parent b4c5bbce
......@@ -431,25 +431,27 @@ static int ahci_port_start(u8 port)
* First item in chunk of DMA memory: 32-slot command table,
* 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);
mem += (AHCI_CMD_SLOT_SZ + 224);
* Second item: Received-FIS area
pp->rx_fis = mem;
pp->rx_fis = virt_to_phys((void *)mem);
mem += AHCI_RX_FIS_SZ;
* Third item: data area for storing a single command
* 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);
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);
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