[PATCH v2] spl: introduce SPL_XIP to config

[Nikita Shubin <nikita.shubin@maquefel.me>]

From: Nikita Shubin <n.shubin@yadro.com>

U-Boot and SPL don't necessary share the same location, so we might end
with U-Boot SPL in read-only memory (XIP) and U-Boot in read-write memory.

In case of non XIP boot mode, we rely on such variables as "hart_lottery"
and "available_harts_lock" which we use as atomics.

The problem is that CONFIG_XIP also propagate to main U-Boot, not only SPL,
so we need CONFIG_SPL_XIP to distinguish SPL XIP from other XIP modes.

This adds an option special for SPL to behave it in XIP manner and we don't
use hart_lottery and available_harts_lock, during start proccess.

Signed-off-by: Nikita Shubin <n.shubin@yadro.com>
---
v1->v2:
Sean Anderson:
	- used Kconfig description suggested by Sean - indeed more cleaner and understandable
---
 arch/riscv/cpu/cpu.c                 | 2 +-
 arch/riscv/cpu/start.S               | 4 ++--
 arch/riscv/include/asm/global_data.h | 2 +-
 arch/riscv/lib/asm-offsets.c         | 2 +-
 arch/riscv/lib/smp.c                 | 2 +-
 common/spl/Kconfig                   | 7 +++++++
 6 files changed, 13 insertions(+), 6 deletions(-)

diff --git a/arch/riscv/cpu/cpu.c b/arch/riscv/cpu/cpu.c
index 9f5fa0bcb3..5d8163b19f 100644
--- a/arch/riscv/cpu/cpu.c
+++ b/arch/riscv/cpu/cpu.c
@@ -19,7 +19,7 @@
  * The variables here must be stored in the data section since they are used
  * before the bss section is available.
  */
-#ifndef CONFIG_XIP
+#if !CONFIG_IS_ENABLED(XIP)
 u32 hart_lottery __section(".data") = 0;
 
 /*
diff --git a/arch/riscv/cpu/start.S b/arch/riscv/cpu/start.S
index ac81783a90..c3c859e667 100644
--- a/arch/riscv/cpu/start.S
+++ b/arch/riscv/cpu/start.S
@@ -122,7 +122,7 @@ call_board_init_f_0:
 call_harts_early_init:
 	jal	harts_early_init
 
-#ifndef CONFIG_XIP
+#if !CONFIG_IS_ENABLED(XIP)
 	/*
 	 * Pick hart to initialize global data and run U-Boot. The other harts
 	 * wait for initialization to complete.
@@ -150,7 +150,7 @@ call_harts_early_init:
 	/* save the boot hart id to global_data */
 	SREG	tp, GD_BOOT_HART(gp)
 
-#ifndef CONFIG_XIP
+#if !CONFIG_IS_ENABLED(XIP)
 	la	t0, available_harts_lock
 	amoswap.w.rl zero, zero, 0(t0)
 
diff --git a/arch/riscv/include/asm/global_data.h b/arch/riscv/include/asm/global_data.h
index 9a146d1d49..a4d3cf430b 100644
--- a/arch/riscv/include/asm/global_data.h
+++ b/arch/riscv/include/asm/global_data.h
@@ -30,7 +30,7 @@ int iccm[CONFIG_NR_CPUS];
 #if CONFIG_IS_ENABLED(SMP)
 	struct ipi_data ipi[CONFIG_NR_CPUS];
 #endif
-#ifndef CONFIG_XIP
+#if !CONFIG_IS_ENABLED(XIP)
 	ulong available_harts;
 #endif
 };
diff --git a/arch/riscv/lib/asm-offsets.c b/arch/riscv/lib/asm-offsets.c
index f1fe089b3d..c4f48c8373 100644
--- a/arch/riscv/lib/asm-offsets.c
+++ b/arch/riscv/lib/asm-offsets.c
@@ -16,7 +16,7 @@ int main(void)
 {
 	DEFINE(GD_BOOT_HART, offsetof(gd_t, arch.boot_hart));
 	DEFINE(GD_FIRMWARE_FDT_ADDR, offsetof(gd_t, arch.firmware_fdt_addr));
-#ifndef CONFIG_XIP
+#if !CONFIG_IS_ENABLED(XIP)
 	DEFINE(GD_AVAILABLE_HARTS, offsetof(gd_t, arch.available_harts));
 #endif
 
diff --git a/arch/riscv/lib/smp.c b/arch/riscv/lib/smp.c
index ba992100ad..f8b756291f 100644
--- a/arch/riscv/lib/smp.c
+++ b/arch/riscv/lib/smp.c
@@ -45,7 +45,7 @@ static int send_ipi_many(struct ipi_data *ipi, int wait)
 			continue;
 		}
 
-#ifndef CONFIG_XIP
+#if !CONFIG_IS_ENABLED(XIP)
 		/* skip if hart is not available */
 		if (!(gd->arch.available_harts & (1 << reg)))
 			continue;
diff --git a/common/spl/Kconfig b/common/spl/Kconfig
index 07c03d611d..777eff5e47 100644
--- a/common/spl/Kconfig
+++ b/common/spl/Kconfig
@@ -27,6 +27,13 @@ config SPL_FRAMEWORK
 	  supports MMC, NAND and YMODEM and other methods loading of U-Boot
 	  and the Linux Kernel.  If unsure, say Y.
 
+config SPL_XIP
+	bool "Enable XIP mode for SPL"
+	help
+	  Support booting SPL from read-only memory (such as XIP). Don't rely on
+	  lock variables (for example hart_lottery and available_harts_lock)
+	  since they cannot be modified.
+
 config SPL_FRAMEWORK_BOARD_INIT_F
 	bool "Define a generic function board_init_f"
 	depends on SPL_FRAMEWORK
-- 
2.35.1