[PATCH] riscv: Split SiFive CLINT support between SPL and U-Boot proper

[Bin Meng]

At present there is only one Kconfig option CONFIG_SIFIVE_CLINT to
control the enabling of SiFive CLINT support in both SPL (M-mode)
and U-Boot proper (S-mode). So for a typical SPL config that the
SiFive CLINT driver is enabled in both SPL and U-Boot proper, that
means the S-mode U-Boot tries to access the memory-mapped CLINT
registers directly, instead of the normal 'rdtime' instruction.

This was not a problem before, as the hardware does not forbid the
access from S-mode. However this becomes an issue now with OpenSBI
commit 8b569803475e ("lib: utils/sys: Add CLINT memregion in the root domain")
that the SiFive CLINT register space is protected by PMP for M-mode
access only. U-Boot proper does not boot any more with the latest
OpenSBI, that access exceptions are fired forever from U-Boot when
trying to read the timer value via the SiFive CLINT driver in U-Boot.

To solve this, we need to split current SiFive CLINT support between
SPL and U-Boot proper, using 2 separate Kconfig options.

Signed-off-by: Bin Meng <bmeng.cn at gmail.com>
---

 arch/riscv/Kconfig                   | 9 ++++++++-
 arch/riscv/cpu/fu540/Kconfig         | 2 +-
 arch/riscv/cpu/generic/Kconfig       | 3 ++-
 arch/riscv/include/asm/global_data.h | 2 +-
 arch/riscv/lib/Makefile              | 2 +-
 drivers/timer/Makefile               | 2 +-
 6 files changed, 14 insertions(+), 6 deletions(-)

diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
index 3f221dccdb..82e10da11e 100644
--- a/arch/riscv/Kconfig
+++ b/arch/riscv/Kconfig
@@ -158,7 +158,14 @@ config DMA_ADDR_T_64BIT
 
 config SIFIVE_CLINT
 	bool
-	depends on RISCV_MMODE || SPL_RISCV_MMODE
+	depends on RISCV_MMODE
+	help
+	  The SiFive CLINT block holds memory-mapped control and status registers
+	  associated with software and timer interrupts.
+
+config SPL_SIFIVE_CLINT
+	bool
+	depends on SPL_RISCV_MMODE
 	help
 	  The SiFive CLINT block holds memory-mapped control and status registers
 	  associated with software and timer interrupts.
diff --git a/arch/riscv/cpu/fu540/Kconfig b/arch/riscv/cpu/fu540/Kconfig
index 616b25650f..dcf099447b 100644
--- a/arch/riscv/cpu/fu540/Kconfig
+++ b/arch/riscv/cpu/fu540/Kconfig
@@ -11,7 +11,7 @@ config SIFIVE_FU540
 	imply CPU
 	imply CPU_RISCV
 	imply RISCV_TIMER if (RISCV_SMODE || SPL_RISCV_SMODE)
-	imply SIFIVE_CLINT if (RISCV_MMODE || SPL_RISCV_MMODE)
+	imply SPL_SIFIVE_CLINT
 	imply CMD_CPU
 	imply SPL_CPU
 	imply SPL_OPENSBI
diff --git a/arch/riscv/cpu/generic/Kconfig b/arch/riscv/cpu/generic/Kconfig
index a4934bb957..e025134b23 100644
--- a/arch/riscv/cpu/generic/Kconfig
+++ b/arch/riscv/cpu/generic/Kconfig
@@ -9,7 +9,8 @@ config GENERIC_RISCV
 	imply CPU
 	imply CPU_RISCV
 	imply RISCV_TIMER if (RISCV_SMODE || SPL_RISCV_SMODE)
-	imply SIFIVE_CLINT if (RISCV_MMODE || SPL_RISCV_MMODE)
+	imply SIFIVE_CLINT if RISCV_MMODE
+	imply SPL_SIFIVE_CLINT if SPL_RISCV_MMODE
 	imply CMD_CPU
 	imply SPL_CPU
 	imply SPL_OPENSBI
diff --git a/arch/riscv/include/asm/global_data.h b/arch/riscv/include/asm/global_data.h
index d3a0b1d221..095484a635 100644
--- a/arch/riscv/include/asm/global_data.h
+++ b/arch/riscv/include/asm/global_data.h
@@ -18,7 +18,7 @@
 struct arch_global_data {
 	long boot_hart;		/* boot hart id */
 	phys_addr_t firmware_fdt_addr;
-#ifdef CONFIG_SIFIVE_CLINT
+#if CONFIG_IS_ENABLED(SIFIVE_CLINT)
 	void __iomem *clint;	/* clint base address */
 #endif
 #ifdef CONFIG_ANDES_PLIC
diff --git a/arch/riscv/lib/Makefile b/arch/riscv/lib/Makefile
index d08cbe9b79..c4cc41434b 100644
--- a/arch/riscv/lib/Makefile
+++ b/arch/riscv/lib/Makefile
@@ -11,7 +11,7 @@ obj-$(CONFIG_CMD_BOOTI) += bootm.o image.o
 obj-$(CONFIG_CMD_GO) += boot.o
 obj-y	+= cache.o
 ifeq ($(CONFIG_$(SPL_)RISCV_MMODE),y)
-obj-$(CONFIG_SIFIVE_CLINT) += sifive_clint.o
+obj-$(CONFIG_$(SPL_)SIFIVE_CLINT) += sifive_clint.o
 obj-$(CONFIG_ANDES_PLIC) += andes_plic.o
 else
 obj-$(CONFIG_SBI) += sbi.o
diff --git a/drivers/timer/Makefile b/drivers/timer/Makefile
index eb5c48cc6c..2ebdeab0ce 100644
--- a/drivers/timer/Makefile
+++ b/drivers/timer/Makefile
@@ -19,7 +19,7 @@ obj-$(CONFIG_RENESAS_OSTM_TIMER) += ostm_timer.o
 obj-$(CONFIG_RISCV_TIMER) += riscv_timer.o
 obj-$(CONFIG_ROCKCHIP_TIMER) += rockchip_timer.o
 obj-$(CONFIG_SANDBOX_TIMER)	+= sandbox_timer.o
-obj-$(CONFIG_SIFIVE_CLINT) += sifive_clint_timer.o
+obj-$(CONFIG_$(SPL_)SIFIVE_CLINT) += sifive_clint_timer.o
 obj-$(CONFIG_STI_TIMER)		+= sti-timer.o
 obj-$(CONFIG_STM32_TIMER)	+= stm32_timer.o
 obj-$(CONFIG_X86_TSC_TIMER)	+= tsc_timer.o
-- 
2.25.1