x86: fsp: Configure SPI opcode registers before SPI is locked down

Some Intel FSP (like Braswell) does SPI lock-down during the call
to fsp_notify(INIT_PHASE_BOOT). But before SPI lock-down is done,
it's bootloader's responsibility to configure the SPI controller's
opcode registers properly otherwise SPI controller driver doesn't
know how to communicate with the SPI flash device.

This introduces a Kconfig option CONFIG_FSP_LOCKDOWN_SPI for such
FSPs. When it is on, U-Boot will configure the SPI opcode registers
before the lock-down.

Signed-off-by: Bin Meng <bmeng.cn@gmail.com>
Reviewed-by: Stefan Roese <sr@denx.de>

arch/x86/Kconfig

@@ -401,6 +401,15 @@ config FSP_BROKEN_HOB
 	  do not overwrite the important boot service data which is used by
 	  FSP, otherwise the subsequent call to fsp_notify() will fail.
 
+config FSP_LOCKDOWN_SPI
+	bool
+	depends on HAVE_FSP
+	help
+	  Some Intel FSP (like Braswell) does SPI lock-down during the call
+	  to fsp_notify(INIT_PHASE_BOOT). This option should be turned on
+	  for such FSP and U-Boot will configure the SPI opcode registers
+	  before the lock-down.
+
 config ENABLE_MRC_CACHE
 	bool "Enable MRC cache"
 	depends on !EFI && !SYS_COREBOOT

arch/x86/lib/fsp/fsp_common.c

@@ -19,6 +19,8 @@
 
 DECLARE_GLOBAL_DATA_PTR;
 
+extern void ich_spi_config_opcode(struct udevice *dev);
+
 int checkcpu(void)
 {
 	return 0;
@@ -49,6 +51,28 @@ void board_final_cleanup(void)
 {
 	u32 status;
 
+#ifdef CONFIG_FSP_LOCKDOWN_SPI
+	struct udevice *dev;
+
+	/*
+	 * Some Intel FSP (like Braswell) does SPI lock-down during the call
+	 * to fsp_notify(INIT_PHASE_BOOT). But before SPI lock-down is done,
+	 * it's bootloader's responsibility to configure the SPI controller's
+	 * opcode registers properly otherwise SPI controller driver doesn't
+	 * know how to communicate with the SPI flash device.
+	 *
+	 * Note we cannot do such configuration elsewhere (eg: during the SPI
+	 * controller driver's probe() routine), because:
+	 *
+	 * 1). U-Boot SPI controller driver does not set the lock-down bit
+	 * 2). Any SPI transfer will corrupt the contents of these registers
+	 *
+	 * Hence we have to do it right here before SPI lock-down bit is set.
+	 */
+	if (!uclass_first_device_err(UCLASS_SPI, &dev))
+		ich_spi_config_opcode(dev);
+#endif
+
 	/* call into FspNotify */
 	debug("Calling into FSP (notify phase INIT_PHASE_BOOT): ");
 	status = fsp_notify(NULL, INIT_PHASE_BOOT);