[U-Boot] [PATCH 36/38] x86: Add support for booting from Fast SPI

[Simon Glass]

Most x86 CPUs use a mechanism where the SPI flash is mapped into the very
top of 32-bit address space, so that it can be executed in place and read
simply by copying from memory. For an 8MB ROM the mapping starts at
0xff800000.

However some recent Intel CPUs do not use a simple 1:1 memory map. Instead
the map starts at a different address and not all of the SPI flash is
accessible through the map. This 'Fast SPI' feature requires that U-Boot
check the location of the map. It is also possible (optionally) to read
from the SPI flash using a driver.

Add support for booting from Fast SPI. The memory-mapped version is used
by both TPL and SPL on apollolake.

Signed-off-by: Simon Glass <sjg at chromium.org>
---

 arch/x86/cpu/intel_common/Makefile   |  1 +
 arch/x86/cpu/intel_common/fast_spi.c | 48 ++++++++++++++++++++++++++++
 arch/x86/include/asm/spl.h           |  1 +
 3 files changed, 50 insertions(+)
 create mode 100644 arch/x86/cpu/intel_common/fast_spi.c

diff --git a/arch/x86/cpu/intel_common/Makefile b/arch/x86/cpu/intel_common/Makefile
index 07f27c29ec..2de567dd9f 100644
--- a/arch/x86/cpu/intel_common/Makefile
+++ b/arch/x86/cpu/intel_common/Makefile
@@ -9,6 +9,7 @@ obj-$(CONFIG_$(SPL_TPL_)X86_32BIT_INIT) += report_platform.o
 obj-$(CONFIG_$(SPL_TPL_)X86_32BIT_INIT) += mrc.o
 endif
 obj-y += cpu.o
+obj-$(CONFIG_SPI_FLASH_INTEL_FAST) += fast_spi.o
 obj-y += lpc.o
 ifndef CONFIG_TARGET_EFI_APP
 obj-$(CONFIG_$(SPL_TPL_)X86_32BIT_INIT) += microcode.o
diff --git a/arch/x86/cpu/intel_common/fast_spi.c b/arch/x86/cpu/intel_common/fast_spi.c
new file mode 100644
index 0000000000..dce3d61b07
--- /dev/null
+++ b/arch/x86/cpu/intel_common/fast_spi.c
@@ -0,0 +1,48 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright 2019 Google LLC
+ */
+
+#include <common.h>
+#include <asm/io.h>
+#include <asm/pci.h>
+#include <asm/arch/fast_spi_def.h>
+#include <asm/arch/pch.h>
+
+/*
+ * Returns bios_start and fills in size of the BIOS region.
+ */
+ulong fast_spi_get_bios_region(struct fast_spi_regs *regs, size_t *bios_size)
+{
+	ulong bios_start, bios_end;
+
+	/*
+	 * BIOS_BFPREG provides info about BIOS-Flash Primary Region Base and
+	 * Limit. Base and Limit fields are in units of 4K.
+	 */
+	u32 val = readl(&regs->bfp);
+
+	bios_start = (val & SPIBAR_BFPREG_PRB_MASK) << 12;
+	bios_end = (((val & SPIBAR_BFPREG_PRL_MASK) >>
+		     SPIBAR_BFPREG_PRL_SHIFT) + 1) << 12;
+	*bios_size = bios_end - bios_start;
+
+	return bios_start;
+}
+
+int fast_spi_get_bios_mmap(ulong *map_basep, size_t *map_sizep, uint *offsetp)
+{
+	struct fast_spi_regs *regs;
+	ulong bar, base, mmio_base;
+
+	/* Special case to find mapping without probing the device */
+	pci_x86_read_config(NULL, PCH_DEV_SPI, PCI_BASE_ADDRESS_0, &bar,
+			    PCI_SIZE_32);
+	mmio_base = bar & PCI_BASE_ADDRESS_MEM_MASK;
+	regs = (struct fast_spi_regs *)mmio_base;
+	base = fast_spi_get_bios_region(regs, map_sizep);
+	*map_basep = (u32)-*map_sizep - base;
+	*offsetp = base;
+
+	return 0;
+}
diff --git a/arch/x86/include/asm/spl.h b/arch/x86/include/asm/spl.h
index 1bef4877eb..cc6cac08f2 100644
--- a/arch/x86/include/asm/spl.h
+++ b/arch/x86/include/asm/spl.h
@@ -11,6 +11,7 @@
 
 enum {
 	BOOT_DEVICE_SPI_MMAP	= 10,
+	BOOT_DEVICE_FAST_SPI,
 	BOOT_DEVICE_CROS_VBOOT,
 };
 
-- 
2.23.0.187.g17f5b7556c-goog