mb/lattepanda: Add support for LattePanda Mu

Add initial support for the LattePanda Mu board, which features:
  - Intel Alder Lake-N N100 processor
  - Samsung K3LK7K70BM-BGCP, 8GB LPDDR5 memory
  - Samsung KLMCG2UCTA-B041, 64GB eMMC storage
  - SO-DIMM 260-pin connector for function expansion

This commit includes:
  - Basic board configuration
  - Memory initialization
  - Essential I/O setup
  - Used UEFITool NE alpha 68 (Nov 4 2023) to extract data.vbt file
    from original BIOS
  - BIOS download link: https://github.com/LattePandaTeam/LattePanda-Mu
    located at "./Softwares/BIOS/DFLT/LP-BS-S70NC1R200-SR-A.bin.zip"

Test Environment:
  - Carrier Board: Lite
  - Payload: mrchromebox/edk2
  - EDK2 Version: uefipayload_202309

Test result
Passed:
  - Windows 11 boot from eMMC
  - Install Ubuntu 24.04 on NVMe SSD
  - Ubuntu 24.04 boot from NVMe SSD
  - USB 3.0/2.0 functionality
  - Realtek RTL8111H-CG-RH Ethernet
  - HDMI Display
    - Audio over HDMI work in Ubuntu 24.04

Known Issues:
  - S3 sleep mode non-functional
  - Power-on after shutdown requires power removal
  - SuperIO UART not detected in Windows 11
  - Audio over HDMI not work in Windows 11
  - Windows 11 BSOD occurs with NVMe SSD installed:
    - Stop code: Machine Check Exception
  - NVMe SSD not working on Windows 11, except when:
    - KDNet Debugging enabled on NIC during boot
    - SSD becomes functional in this scenario

Change-Id: I79696bdd837a221860b32f54629212c3346dca66
Signed-off-by: KunYi Chen <kunyi.chen@gmail.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/83719
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Felix Held <felix-coreboot@felixheld.de>

1 files changed, 32 insertions, 0 deletions

diff --git a/src/mainboard/lattepanda/mu/include/baseboard/variants.h b/src/mainboard/lattepanda/mu/include/baseboard/variants.h
new file mode 100644
index 0000000000..61b0f68887
--- /dev/null
+++ b/src/mainboard/lattepanda/mu/include/baseboard/variants.h
@@ -0,0 +1,32 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+
+#ifndef __BASEBOARD_VARIANTS_H__
+#define __BASEBOARD_VARIANTS_H__
+
+#include <soc/gpio.h>
+#include <soc/meminit.h>
+#include <stdint.h>
+
+/* Functions to configure GPIO as per variant schematics */
+void variant_configure_gpio_pads(void);
+void variant_configure_early_gpio_pads(void);
+
+size_t variant_memory_sku(void);
+const struct mb_cfg *variant_memory_params(void);
+void rpl_memory_params(FSPM_UPD *memupd);
+
+/* Modify devictree settings during ramstage */
+void variant_devtree_update(void);
+struct cpu_power_limits {
+	uint16_t mchid;
+	u8 cpu_tdp;
+	unsigned int pl1_min_power;
+	unsigned int pl1_max_power;
+	unsigned int pl2_min_power;
+	unsigned int pl2_max_power;
+	unsigned int pl4_power;
+};
+/* Modify Power Limit devictree settings during ramstage */
+void variant_update_power_limits(void);
+
+#endif /*__BASEBOARD_VARIANTS_H__ */