From df8d94e067f7f080eb4dc5af33755218e23d506a Mon Sep 17 00:00:00 2001 From: "Gabriel L. Somlo" Date: Fri, 19 Feb 2016 13:20:25 -0500 Subject: fw_cfg: expose control register size in fw_cfg.h MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Expose the size of the control register (FW_CFG_CTL_SIZE) in fw_cfg.h. Add comment to fw_cfg_io_realize() pointing out that since the 8-bit data register is always subsumed by the 16-bit control register in the port I/O case, we use the control register width as the *total* width of the (classic, non-DMA) port I/O region reserved for the device. Cc: Marc Marí Signed-off-by: Gabriel Somlo Reviewed-by: Laszlo Ersek Reviewed-by: Marc Marí Message-id: 1455906029-25565-2-git-send-email-somlo@cmu.edu Signed-off-by: Gerd Hoffmann --- hw/nvram/fw_cfg.c | 4 +++- include/hw/nvram/fw_cfg.h | 3 +++ 2 files changed, 6 insertions(+), 1 deletion(-) diff --git a/hw/nvram/fw_cfg.c b/hw/nvram/fw_cfg.c index f3acb47..7866248 100644 --- a/hw/nvram/fw_cfg.c +++ b/hw/nvram/fw_cfg.c @@ -32,7 +32,6 @@ #include "qemu/error-report.h" #include "qemu/config-file.h" -#define FW_CFG_CTL_SIZE 2 #define FW_CFG_NAME "fw_cfg" #define FW_CFG_PATH "/machine/" FW_CFG_NAME @@ -886,6 +885,9 @@ static void fw_cfg_io_realize(DeviceState *dev, Error **errp) FWCfgIoState *s = FW_CFG_IO(dev); SysBusDevice *sbd = SYS_BUS_DEVICE(dev); + /* when using port i/o, the 8-bit data register ALWAYS overlaps + * with half of the 16-bit control register. Hence, the total size + * of the i/o region used is FW_CFG_CTL_SIZE */ memory_region_init_io(&s->comb_iomem, OBJECT(s), &fw_cfg_comb_mem_ops, FW_CFG(s), "fwcfg", FW_CFG_CTL_SIZE); sysbus_add_io(sbd, s->iobase, &s->comb_iomem); diff --git a/include/hw/nvram/fw_cfg.h b/include/hw/nvram/fw_cfg.h index 5d19975..4315f4e 100644 --- a/include/hw/nvram/fw_cfg.h +++ b/include/hw/nvram/fw_cfg.h @@ -44,6 +44,9 @@ #define FW_CFG_INVALID 0xffff +/* width in bytes of fw_cfg control register */ +#define FW_CFG_CTL_SIZE 0x02 + #define FW_CFG_MAX_FILE_PATH 56 #ifndef NO_QEMU_PROTOS -- cgit v1.1