From 2ab908bcf2c7ad31a051cbdc47b346aa92aba0e5 Mon Sep 17 00:00:00 2001
From: Tim Lin <tim2.lin@ite.corp-partner.google.com>
Date: Mon, 1 Jul 2024 17:24:34 +0800
Subject: [PATCH] soc: it8xxx2: linker: Move kernel library to RAM to enhance
 performance

Place kernel library in ILM. This can improve performance.

test:
Print the message 10000 times with 1ms sleep interval to compare the
time difference before and after adding RAM code on the it82002bw evb.

                         RAM code size    save time
original:                1954 bytes
libkernel.a:            +8941 bytes      -649ms

Signed-off-by: Tim Lin <tim2.lin@ite.corp-partner.google.com>
---
 soc/ite/ec/it8xxx2/Kconfig   |  7 +++++++
 soc/ite/ec/it8xxx2/linker.ld | 11 +++++++++++
 2 files changed, 18 insertions(+)

diff --git a/soc/ite/ec/it8xxx2/Kconfig b/soc/ite/ec/it8xxx2/Kconfig
index 2dfe2d5afc9..6ddf099d026 100644
--- a/soc/ite/ec/it8xxx2/Kconfig
+++ b/soc/ite/ec/it8xxx2/Kconfig
@@ -197,6 +197,13 @@ config SOC_IT8XXX2_SERIAL_IN_RAM
 	  Place serial handling (Include uart_ns16550.c and uart_ite_it8xxx2.c) code
 	  in ILM. This can improve performance.
 
+config SOC_IT8XXX2_KERNEL_IN_RAM
+	bool "Place kernel handling code in RAM"
+	select SOC_IT8XXX2_USE_ILM
+	select SOC_IT8XXX2_LIBRARY_TO_RAM
+	help
+	  Place kernel handling code in ILM. This can significantly improve performance.
+
 config SOC_IT8XXX2_SHA256_HW_ACCELERATE
 	bool "HW SHA256 calculation"
 	help
diff --git a/soc/ite/ec/it8xxx2/linker.ld b/soc/ite/ec/it8xxx2/linker.ld
index 0c4e3d483dd..6f1577a7930 100644
--- a/soc/ite/ec/it8xxx2/linker.ld
+++ b/soc/ite/ec/it8xxx2/linker.ld
@@ -176,6 +176,9 @@ SECTIONS
 #ifdef CONFIG_SOC_IT8XXX2_SERIAL_IN_RAM
 			*libdrivers__serial.a:*
 #endif
+#ifdef CONFIG_SOC_IT8XXX2_KERNEL_IN_RAM
+			*libkernel.a:*
+#endif
 #ifdef CONFIG_SOC_IT8XXX2_LIBRARY_TO_RAM
 		)
 			.text
@@ -188,6 +191,9 @@ SECTIONS
 #ifdef CONFIG_SOC_IT8XXX2_SERIAL_IN_RAM
 			*libdrivers__serial.a:*
 #endif
+#ifdef CONFIG_SOC_IT8XXX2_KERNEL_IN_RAM
+			*libkernel.a:*
+#endif
 #ifdef CONFIG_SOC_IT8XXX2_LIBRARY_TO_RAM
 		)
 			.text.*
@@ -219,6 +225,11 @@ SECTIONS
 		*libdrivers__serial.a:*(.text .text.*)
 		*libdrivers__serial.a:*(.rodata .rodata.*)
 		*libdrivers__serial.a:*(.srodata .srodata.*)
+#endif
+#ifdef CONFIG_SOC_IT8XXX2_KERNEL_IN_RAM
+		*libkernel.a:*(.text .text.*)
+		*libkernel.a:*(.rodata .rodata.*)
+		*libkernel.a:*(.srodata .srodata.*)
 #endif
 		__ilm_flash_end = .;
 		/* ILM mapping is always a multiple of 4k size; ensure following