soc/intel/common/fast_spi: Add custom boot media device

This change enables support for a custom boot media device in fast SPI
controller driver if the platform supports additional decode window
for mapping BIOS regions greater than 16MiB. Following new Kconfigs
are added:
1. FAST_SPI_SUPPORTS_EXT_BIOS_WINDOW: SoC can select this to indicate
support for extended BIOS window.
2. EXT_BIOS_WIN_BASE: If FAST_SPI_SUPPORTS_EXT_BIOS_WINDOW is
selected, this provides the base address of the host space that is
reserved for mapping the extended window.
3. EXT_BIOS_WIN_SIZE: If FAST_SPI_SUPPORTS_EXT_BIOS_WINDOW is
selected, this provides the size of the host space reserved for
mapping extended window.

If platform indicates support for extended BIOS decode window,
cbfstool add command is provided additional parameters for the decode
window using --ext-win-base and --ext-win-size.

It is the responsibility of the mainboard fmap author to ensure that
the sections in the BIOS region do not cross 16MiB boundary as the
host space windows are not contiguous. This change adds a build time
check to ensure no sections in FMAP cross the 16MiB boundary.

Even though the platform supports extended window, it depends upon the
size of BIOS region (which in turn depends on SPI flash size) whether
and how much of the additional window is utilized at runtime. This
change also provides helper functions for rest of the coreboot
components to query how much of the extended window is actually
utilized.

BUG=b:171534504

Change-Id: I1b564aed9809cf14b40a3b8e907622266fc782e2
Signed-off-by: Furquan Shaikh <furquan@google.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/47659
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Tim Wawrzynczak <twawrzynczak@chromium.org>

1 files changed, 7 insertions, 0 deletions

diff --git a/src/soc/intel/common/block/include/intelblocks/fast_spi.h b/src/soc/intel/common/block/include/intelblocks/fast_spi.h
index 52ffdb319d..0a7e64dad4 100644
--- a/src/soc/intel/common/block/include/intelblocks/fast_spi.h
+++ b/src/soc/intel/common/block/include/intelblocks/fast_spi.h
@@ -74,4 +74,11 @@ bool fast_spi_wpd_status(void);
  */
 void fast_spi_enable_wp(void);
 
+/*
+ * Get base and size of extended BIOS decode window used at runtime in host address space. If
+ * the BIOS region is not greater than 16MiB, then this function returns 0 for both base and
+ * size.
+ */
+void fast_spi_get_ext_bios_window(uintptr_t *base, size_t *size);
+
 #endif	/* SOC_INTEL_COMMON_BLOCK_FAST_SPI_H */