Re: [PATCH 1/3] arm: mach-k3: am62a: Fixup CPU core, DSS, CAN-FD and Video-codec nodes in fdt

[Daniel Schultz]

On 5/1/25 14:28, Nishanth Menon wrote:
On 16:12-20250430, Aparna Patra wrote:
AM62A SOC is available in multiple variants:
-CPU cores (Cortex-A) AM62Ax1 (1 core),
  AM62Ax2 (2 cores), AM62Ax4 (4 cores)
-With and without DSS, CAN-FD & Video-codec support

Remove the relevant FDT nodes by reading the actual configuration
from the SoC registers, with that change it is possible to have a single
dts/dtb file handling the different variants at runtime.

Signed-off-by: Aparna Patra <a-pa...@ti.com>
---
  arch/arm/mach-k3/am62ax/am62a7_fdt.c          | 41 +++++++++++++++++++
  .../arm/mach-k3/include/mach/am62a_hardware.h | 40 ++++++++++++++++++
  2 files changed, 81 insertions(+)

diff --git a/arch/arm/mach-k3/am62ax/am62a7_fdt.c 
b/arch/arm/mach-k3/am62ax/am62a7_fdt.c
index 7f764ab36b..56fd658202 100644
--- a/arch/arm/mach-k3/am62ax/am62a7_fdt.c
+++ b/arch/arm/mach-k3/am62ax/am62a7_fdt.c
@@ -8,8 +8,49 @@
  
  #include "../common_fdt.h"
  
+static void fdt_fixup_cores_wdt_nodes_am62a(void *blob, int core_nr)
+{
+       char node_path[32];
+
+       if (core_nr < 1)
+               return;
+
+       for (; core_nr < 4; core_nr++) {
+               snprintf(node_path, sizeof(node_path), "/cpus/cpu@%d", core_nr);
+               fdt_del_node_path(blob, node_path);
+               snprintf(node_path, sizeof(node_path), 
"/cpus/cpu-map/cluster0/core%d", core_nr);
+               fdt_del_node_path(blob, node_path);
+               snprintf(node_path, sizeof(node_path), 
"/bus@f0000/watchdog@e0%d0000", core_nr);
+               fdt_del_node_path(blob, node_path);
+       }
+}
+
+static void fdt_fixup_dss_nodes_am62a(void *blob, bool has_dss)
+{
+       if (!has_dss) {
+               fdt_del_node_path(blob, "/bus@f0000/dss@30200000");
+               fdt_del_node_path(blob, 
"/bus@f0000/pinctrl@f4000/main-dss0-default-pins");
+       }
+}
+
+static void fdt_fixup_video_codec_nodes_am62a(void *blob, bool has_video_codec)
+{
+       if (!has_video_codec)
+               fdt_del_node_path(blob, "/bus@f0000/video-codec@30210000");
+}
+
+static void fdt_fixup_canfd_nodes_am62a(void *blob, bool has_canfd)
+{
+       if (!has_canfd)
+               fdt_del_node_path(blob, "/bus@f0000/can@20701000");
+}
+
  int ft_system_setup(void *blob, struct bd_info *bd)
  {
+       fdt_fixup_cores_wdt_nodes_am62a(blob, k3_get_core_nr());
+       fdt_fixup_dss_nodes_am62a(blob, k3_has_dss());
+       fdt_fixup_video_codec_nodes_am62a(blob, k3_has_video_codec());
+       fdt_fixup_canfd_nodes_am62a(blob, k3_has_canfd());
        fdt_fixup_reserved(blob, "tfa", CONFIG_K3_ATF_LOAD_ADDR, 0x80000);
        fdt_fixup_reserved(blob, "optee", CONFIG_K3_OPTEE_LOAD_ADDR, 0x1800000);
  
diff --git a/arch/arm/mach-k3/include/mach/am62a_hardware.h b/arch/arm/mach-k3/include/mach/am62a_hardware.h
index cd61abe018..ab281129d7 100644
--- a/arch/arm/mach-k3/include/mach/am62a_hardware.h
+++ b/arch/arm/mach-k3/include/mach/am62a_hardware.h
@@ -19,6 +19,18 @@
  #define MCU_CTRL_MMR0_BASE                    0x04500000
  #define WKUP_CTRL_MMR0_BASE                   0x43000000
  
+#define CTRLMMR_WKUP_JTAG_DEVICE_ID		(WKUP_CTRL_MMR0_BASE + 0x18)
+#define JTAG_DEV_CORE_NR_MASK                  GENMASK(19, 18)
+#define JTAG_DEV_CORE_NR_SHIFT                 18
+#define JTAG_DEV_CANFD_MASK                    BIT(15)
+#define JTAG_DEV_CANFD_SHIFT                   15
+#define JTAG_DEV_VIDEO_CODEC_MASK                      BIT(14)
+#define JTAG_DEV_VIDEO_CODEC_SHIFT                     14
+#define JTAG_DEV_DSS_MASK                      GENMASK(16, 13)
+#define JTAG_DEV_DSS_SHIFT                     13
+
+#define JTAG_DEV_HAS_DSS_VALUE                 0xD
+
  #define CTRLMMR_MAIN_DEVSTAT                  (WKUP_CTRL_MMR0_BASE + 0x30)
  #define MAIN_DEVSTAT_PRIMARY_BOOTMODE_MASK    GENMASK(6, 3)
  #define MAIN_DEVSTAT_PRIMARY_BOOTMODE_SHIFT   3
@@ -86,6 +98,34 @@
  #define TI_SRAM_SCRATCH_BOARD_EEPROM_START    0x70000001
  #endif /* CONFIG_CPU_V7R */
  
+static inline int k3_get_core_nr(void)
+{
+       u32 dev_id = readl(CTRLMMR_WKUP_JTAG_DEVICE_ID);
+
+       return ((dev_id & JTAG_DEV_CORE_NR_MASK) >> JTAG_DEV_CORE_NR_SHIFT) + 1;
+}
+

I can see these three following components are optional but I don't see 
any silicon devices without them. The AM62A processor data sheet only 
lists devices with different A53 and C7 options.

BTW: C7x fixup is missing in this series ;)

+static inline int k3_has_dss(void)
+{
+       u32 dev_id = readl(CTRLMMR_WKUP_JTAG_DEVICE_ID);
+
+       return (JTAG_DEV_HAS_DSS_VALUE == ((dev_id & JTAG_DEV_DSS_MASK) >> 
JTAG_DEV_DSS_SHIFT));
+}
+
+static inline int k3_has_video_codec(void)
+{
+       u32 dev_id = readl(CTRLMMR_WKUP_JTAG_DEVICE_ID);
+
+       return !((dev_id & JTAG_DEV_VIDEO_CODEC_MASK) >> 
JTAG_DEV_VIDEO_CODEC_SHIFT);
+}
+
+static inline int k3_has_canfd(void)
+{
+       u32 dev_id = readl(CTRLMMR_WKUP_JTAG_DEVICE_ID);
+
+       return (dev_id & JTAG_DEV_CANFD_MASK) >> JTAG_DEV_CANFD_SHIFT;
+}
+
  #if defined(CONFIG_SYS_K3_SPL_ATF) && !defined(__ASSEMBLY__)
  
  static const u32 put_device_ids[] = {};
--
2.34.1

We should do a proper framework for this that scales multiple devices.

I agree, this should be reworked afterwards and moved into a framework. 
We have literally the same logic for AM62 and AM62Ax. I also have 
temperature fixup patches for the AM64 which are identical again. Would 
be nice to move most of this logic into a common part.

Thanks for sending those patches!

- Daniel