[PATCH] arm: mach-k3: am62: fixup thermal cooling device cpus

[Parth Pancholi]

From: Parth Pancholi <parth.pancholi at toradex.com>

AM62x devices now support CPU throttling based on thermal alerts
with a Linux commit 10e7bfd8114c ("arm64: dts: ti: k3-am62: Enable
CPU freq throttling on thermal alert"). However, this functionality
does not work correctly across all variants of the AM62x SoCs
which have different numbers of Cortex-A CPU cores: AM62x1 (1 core),
AM62x2 (2 cores), and AM62x4 (4 cores). On single-core and dual-core
AM62x devices, the following error is observed in the Linux kernel:

OF: /thermal-zones/main0-thermal/cooling-maps/map0: could not find
    phandle 94
OF: /thermal-zones/main1-thermal/cooling-maps/map0: could not find
    phandle 94

This commit adds a fixup to dynamically adjust the cooling-device
nodes in the thermal zones based on the actual number of CPU cores
available. This resolves the issue of CPU throttling not working
correctly on single-core and dual-core AM62x devices, while
maintaining the functionality for AM62x quad-core devices.

A similar approach is implemented for example on i.MX8MM SoC.

Signed-off-by: Parth Pancholi <parth.pancholi at toradex.com>
---
 arch/arm/mach-k3/am62x/am625_fdt.c | 36 ++++++++++++++++++++++++++++++
 1 file changed, 36 insertions(+)

diff --git a/arch/arm/mach-k3/am62x/am625_fdt.c b/arch/arm/mach-k3/am62x/am625_fdt.c
index 8fe200a42318..ab9b573f3cff 100644
--- a/arch/arm/mach-k3/am62x/am625_fdt.c
+++ b/arch/arm/mach-k3/am62x/am625_fdt.c
@@ -5,6 +5,7 @@
 
 #include <asm/hardware.h>
 #include <fdt_support.h>
+#include <fdtdec.h>
 
 #include "../common_fdt.h"
 
@@ -75,12 +76,47 @@ static void fdt_fixup_thermal_zone_nodes_am625(void *blob, int maxc)
 	}
 }
 
+static void fdt_fixup_thermal_cooling_device_cpus_am625(void *blob, int core_nr)
+{
+	static const char * const thermal_path[] = {
+		"/thermal-zones/main0-thermal/cooling-maps/map0",
+		"/thermal-zones/main1-thermal/cooling-maps/map0"
+	};
+
+	int node, cnt, i, ret;
+	u32 cooling_dev[12];
+
+	for (i = 0; i < ARRAY_SIZE(thermal_path); i++) {
+		int new_count = core_nr * 3;  /* Each CPU has 3 entries */
+		int j;
+
+		node = fdt_path_offset(blob, thermal_path[i]);
+		if (node < 0)
+			continue; /* Not found, skip it */
+
+		cnt = fdtdec_get_int_array_count(blob, node, "cooling-device",
+						 cooling_dev, ARRAY_SIZE(cooling_dev));
+		if (cnt < 0)
+			continue;
+
+		for (j = 0; j < new_count; j++)
+			cooling_dev[j] = cpu_to_fdt32(cooling_dev[j]);
+
+		ret = fdt_setprop(blob, node, "cooling-device", cooling_dev,
+				  new_count * sizeof(u32));
+		if (ret < 0)
+			printf("Error %s, cooling-device setprop failed %d\n",
+			       thermal_path[i], ret);
+	}
+}
+
 int ft_system_setup(void *blob, struct bd_info *bd)
 {
 	fdt_fixup_cores_nodes_am625(blob, k3_get_core_nr());
 	fdt_fixup_gpu_nodes_am625(blob, k3_has_gpu());
 	fdt_fixup_pru_node_am625(blob, k3_has_pru());
 	fdt_fixup_thermal_zone_nodes_am625(blob, k3_get_max_temp());
+	fdt_fixup_thermal_cooling_device_cpus_am625(blob, k3_get_core_nr());
 	fdt_fixup_reserved(blob, "tfa", CONFIG_K3_ATF_LOAD_ADDR, 0x80000);
 	fdt_fixup_reserved(blob, "optee", CONFIG_K3_OPTEE_LOAD_ADDR, 0x1800000);
 
-- 
2.34.1