[PATCH v2] riscv: andesv5: Prefer using the generic RISC-V timer driver in S-mode

[Yu Chien Peter Lin]

The Andes PLMT driver directly accesses the mtime MMIO region,
indicating its intended use in the M-mode boot stage. However,
since U-Boot proper (S-mode) also uses the PLMT driver, we need
to specifically mark the region as readable through PMPCFGx (or
S/U-mode read-only shared data region for Smepmp) in OpenSBI.

Granting permission for this case doesn't make sense. Instead,
we should use the generic RISC-V timer driver to read the mtime
through the TIME CSR. Therefore, we add the SPL_ANDES_PLMT_TIMER
config, which ensures that the PLMT driver is linked exclusively
against M-mode U-Boot or U-Boot SPL binaries.

Signed-off-by: Yu Chien Peter Lin <peterlin at andestech.com>
Reviewed-by: Samuel Holland <samuel at sholland.org>
---
Changes v1 -> v2:
- Drop imply conditions for *ANDES_PLMT_TIMER
- Add Samuel's RB-tag
---
 arch/riscv/cpu/andesv5/Kconfig | 3 ++-
 drivers/timer/Kconfig          | 9 ++++++++-
 drivers/timer/Makefile         | 2 +-
 3 files changed, 11 insertions(+), 3 deletions(-)

diff --git a/arch/riscv/cpu/andesv5/Kconfig b/arch/riscv/cpu/andesv5/Kconfig
index 82bb5a2a53..57177b7b64 100644
--- a/arch/riscv/cpu/andesv5/Kconfig
+++ b/arch/riscv/cpu/andesv5/Kconfig
@@ -4,8 +4,9 @@ config RISCV_NDS
 	imply CPU
 	imply CPU_RISCV
 	imply RISCV_TIMER if (RISCV_SMODE || SPL_RISCV_SMODE)
+	imply ANDES_PLMT_TIMER
+	imply SPL_ANDES_PLMT_TIMER
 	imply ANDES_PLICSW if (RISCV_MMODE || SPL_RISCV_MMODE)
-	imply ANDES_PLMT_TIMER if (RISCV_MMODE || SPL_RISCV_MMODE)
 	imply V5L2_CACHE
 	imply SPL_CPU
 	imply SPL_OPENSBI
diff --git a/drivers/timer/Kconfig b/drivers/timer/Kconfig
index 915b2af160..157298a941 100644
--- a/drivers/timer/Kconfig
+++ b/drivers/timer/Kconfig
@@ -59,7 +59,14 @@ config ALTERA_TIMER
 
 config ANDES_PLMT_TIMER
 	bool
-	depends on RISCV_MMODE || SPL_RISCV_MMODE
+	depends on RISCV_MMODE
+	help
+	  The Andes PLMT block holds memory-mapped mtime register
+	  associated with timer tick.
+
+config SPL_ANDES_PLMT_TIMER
+	bool
+	depends on SPL_RISCV_MMODE
 	help
 	  The Andes PLMT block holds memory-mapped mtime register
 	  associated with timer tick.
diff --git a/drivers/timer/Makefile b/drivers/timer/Makefile
index 1ca74805fd..1f5c16fdf3 100644
--- a/drivers/timer/Makefile
+++ b/drivers/timer/Makefile
@@ -4,7 +4,7 @@
 
 obj-y += timer-uclass.o
 obj-$(CONFIG_ALTERA_TIMER)	+= altera_timer.o
-obj-$(CONFIG_ANDES_PLMT_TIMER) += andes_plmt_timer.o
+obj-$(CONFIG_$(SPL_)ANDES_PLMT_TIMER) += andes_plmt_timer.o
 obj-$(CONFIG_ARC_TIMER)	+= arc_timer.o
 obj-$(CONFIG_ARM_TWD_TIMER)	+= arm_twd_timer.o
 obj-$(CONFIG_AST_TIMER)	+= ast_timer.o
-- 
2.40.1