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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>
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@ -274,6 +274,36 @@ static int fw_cfg_select(FWCfgState *s, uint16_t key)
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return ret;
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}
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static uint64_t fw_cfg_data_read(void *opaque, hwaddr addr, unsigned size)
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{
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FWCfgState *s = opaque;
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int arch = !!(s->cur_entry & FW_CFG_ARCH_LOCAL);
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FWCfgEntry *e = (s->cur_entry == FW_CFG_INVALID) ? NULL :
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&s->entries[arch][s->cur_entry & FW_CFG_ENTRY_MASK];
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uint64_t value = 0;
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assert(size > 0 && size <= sizeof(value));
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if (s->cur_entry != FW_CFG_INVALID && e->data && s->cur_offset < e->len) {
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/* The least significant 'size' bytes of the return value are
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* expected to contain a string preserving portion of the item
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* data, padded with zeros on the right in case we run out early.
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* In technical terms, we're composing the host-endian representation
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* of the big endian interpretation of the fw_cfg string.
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*/
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do {
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value = (value << 8) | e->data[s->cur_offset++];
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} while (--size && s->cur_offset < e->len);
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/* If size is still not zero, we *did* run out early, so continue
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* left-shifting, to add the appropriate number of padding zeros
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* on the right.
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*/
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value <<= 8 * size;
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}
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trace_fw_cfg_read(s, value);
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return value;
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}
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static uint8_t fw_cfg_read(FWCfgState *s)
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{
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int arch = !!(s->cur_entry & FW_CFG_ARCH_LOCAL);
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@ -291,19 +321,6 @@ static uint8_t fw_cfg_read(FWCfgState *s)
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return ret;
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}
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static uint64_t fw_cfg_data_mem_read(void *opaque, hwaddr addr,
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unsigned size)
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{
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FWCfgState *s = opaque;
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uint64_t value = 0;
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unsigned i;
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for (i = 0; i < size; ++i) {
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value = (value << 8) | fw_cfg_read(s);
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}
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return value;
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}
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static void fw_cfg_data_mem_write(void *opaque, hwaddr addr,
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uint64_t value, unsigned size)
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{
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@ -485,7 +502,7 @@ static const MemoryRegionOps fw_cfg_ctl_mem_ops = {
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};
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static const MemoryRegionOps fw_cfg_data_mem_ops = {
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.read = fw_cfg_data_mem_read,
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.read = fw_cfg_data_read,
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.write = fw_cfg_data_mem_write,
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.endianness = DEVICE_BIG_ENDIAN,
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.valid = {
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@ -196,7 +196,7 @@ ecc_diag_mem_readb(uint64_t addr, uint32_t ret) "Read diagnostic %"PRId64"= %02x
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# hw/nvram/fw_cfg.c
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fw_cfg_select(void *s, uint16_t key, int ret) "%p key %d = %d"
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fw_cfg_read(void *s, uint8_t ret) "%p = %d"
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fw_cfg_read(void *s, uint64_t ret) "%p = %"PRIx64
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fw_cfg_add_file(void *s, int index, char *name, size_t len) "%p #%d: %s (%zd bytes)"
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# hw/block/hd-geometry.c
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