fw_cfg: add generic non-DMA read method

Introduce fw_cfg_data_read(), a generic read method which works
on all access widths (1 through 8 bytes, inclusive), and can be
used during both IOPort and MMIO read accesses.

To maintain legibility, only fw_cfg_data_mem_read() (the MMIO
data read method) is replaced by this patch. The new method
essentially unwinds the fw_cfg_data_mem_read() + fw_cfg_read()
combo, but without unnecessarily repeating all the validity
checks performed by the latter on each byte being read.

This patch also modifies the trace_fw_cfg_read prototype to
accept a 64-bit value argument, allowing it to work properly
with the new read method, but also remain backward compatible
with existing call sites.

Cc: Laszlo Ersek <lersek@redhat.com>
Cc: Gerd Hoffmann <kraxel@redhat.com>
Cc: Marc Marí <markmb@redhat.com>
Signed-off-by: Gabriel Somlo <somlo@cmu.edu>
Reviewed-by: Laszlo Ersek <lersek@redhat.com>
Message-id: 1446733972-1602-6-git-send-email-somlo@cmu.edu
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
This commit is contained in:
Gabriel L. Somlo 2015-11-05 09:32:51 -05:00 committed by Gerd Hoffmann
parent 66f8fd9dda
commit 38bf20931a
2 changed files with 32 additions and 15 deletions

View File

@ -274,6 +274,36 @@ static int fw_cfg_select(FWCfgState *s, uint16_t key)
return ret;
}
static uint64_t fw_cfg_data_read(void *opaque, hwaddr addr, unsigned size)
{
FWCfgState *s = opaque;
int arch = !!(s->cur_entry & FW_CFG_ARCH_LOCAL);
FWCfgEntry *e = (s->cur_entry == FW_CFG_INVALID) ? NULL :
&s->entries[arch][s->cur_entry & FW_CFG_ENTRY_MASK];
uint64_t value = 0;
assert(size > 0 && size <= sizeof(value));
if (s->cur_entry != FW_CFG_INVALID && e->data && s->cur_offset < e->len) {
/* The least significant 'size' bytes of the return value are
* expected to contain a string preserving portion of the item
* data, padded with zeros on the right in case we run out early.
* In technical terms, we're composing the host-endian representation
* of the big endian interpretation of the fw_cfg string.
*/
do {
value = (value << 8) | e->data[s->cur_offset++];
} while (--size && s->cur_offset < e->len);
/* If size is still not zero, we *did* run out early, so continue
* left-shifting, to add the appropriate number of padding zeros
* on the right.
*/
value <<= 8 * size;
}
trace_fw_cfg_read(s, value);
return value;
}
static uint8_t fw_cfg_read(FWCfgState *s)
{
int arch = !!(s->cur_entry & FW_CFG_ARCH_LOCAL);
@ -291,19 +321,6 @@ static uint8_t fw_cfg_read(FWCfgState *s)
return ret;
}
static uint64_t fw_cfg_data_mem_read(void *opaque, hwaddr addr,
unsigned size)
{
FWCfgState *s = opaque;
uint64_t value = 0;
unsigned i;
for (i = 0; i < size; ++i) {
value = (value << 8) | fw_cfg_read(s);
}
return value;
}
static void fw_cfg_data_mem_write(void *opaque, hwaddr addr,
uint64_t value, unsigned size)
{
@ -485,7 +502,7 @@ static const MemoryRegionOps fw_cfg_ctl_mem_ops = {
};
static const MemoryRegionOps fw_cfg_data_mem_ops = {
.read = fw_cfg_data_mem_read,
.read = fw_cfg_data_read,
.write = fw_cfg_data_mem_write,
.endianness = DEVICE_BIG_ENDIAN,
.valid = {

View File

@ -196,7 +196,7 @@ ecc_diag_mem_readb(uint64_t addr, uint32_t ret) "Read diagnostic %"PRId64"= %02x
# hw/nvram/fw_cfg.c
fw_cfg_select(void *s, uint16_t key, int ret) "%p key %d = %d"
fw_cfg_read(void *s, uint8_t ret) "%p = %d"
fw_cfg_read(void *s, uint64_t ret) "%p = %"PRIx64
fw_cfg_add_file(void *s, int index, char *name, size_t len) "%p #%d: %s (%zd bytes)"
# hw/block/hd-geometry.c