drivers: syscon: Introduce BFLB Efuse driver

This introduces a driver used to access bouffalolab efuses via syscon API

Signed-off-by: Camille BAUD <mail@massdriver.space>

drivers/syscon/CMakeLists.txt

@@ -2,3 +2,4 @@
 
 zephyr_library()
 zephyr_library_sources_ifdef(CONFIG_SYSCON_GENERIC          syscon.c)
+zephyr_library_sources_ifdef(CONFIG_SYSCON_BFLB_EFUSE       syscon_bflb_efuse.c)

drivers/syscon/Kconfig

@@ -38,4 +38,6 @@ config SYSCON_INIT_PRIORITY
 	  initialized earlier in the startup cycle. If unsure, leave at default
 	  value
 
+source "drivers/syscon/Kconfig.bflb_efuse"
+
 endif # SYSCON

drivers/syscon/Kconfig.bflb_efuse

@@ -0,0 +1,9 @@
+# Copyright (c) 2024-2025 MASSDRIVER EI (massdriver.space)
+# SPDX-License-Identifier: Apache-2.0
+
+config SYSCON_BFLB_EFUSE
+	bool "Bouffalolab EFUSEs driver"
+	default y
+	depends on DT_HAS_BFLB_EFUSE_ENABLED
+	help
+	  E-Fuse access via SYSCON API for Bouffalolab platforms.

drivers/syscon/syscon_bflb_efuse.c

@@ -0,0 +1,248 @@
+/*
+ * Copyright (c) 2025 MASSDRIVER EI (massdriver.space)
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+#define DT_DRV_COMPAT bflb_efuse
+
+#include <zephyr/drivers/syscon.h>
+#include <zephyr/kernel.h>
+
+#include <zephyr/logging/log.h>
+LOG_MODULE_REGISTER(efuse_bflb, CONFIG_SYSCON_LOG_LEVEL);
+
+#include <bouffalolab/bl60x/bflb_soc.h>
+#include <bouffalolab/bl60x/hbn_reg.h>
+#include <bouffalolab/bl60x/ef_ctrl_reg.h>
+#include <bouffalolab/bl60x/extra_defines.h>
+
+struct efuse_bflb_data {
+	uint8_t cache[DT_INST_PROP(0, size)];
+	bool cached;
+};
+
+struct efuse_bflb_config {
+	uintptr_t addr;
+	size_t size;
+};
+
+static inline void efuse_bflb_clock_settle(void)
+{
+	__asm__ volatile (".rept 15 ; nop ; .endr");
+}
+
+/* 32 Mhz Oscillator: 0
+ * crystal: 1
+ * PLL and 32M: 2
+ * PLL and crystal: 3
+ */
+static void efuse_bflb_set_root_clock(uint32_t clock)
+{
+	uint32_t tmp;
+
+	/* invalid value, fallback to internal 32M */
+	if (clock > 3) {
+		clock = 0;
+	}
+	tmp = sys_read32(HBN_BASE + HBN_GLB_OFFSET);
+	tmp = (tmp & HBN_ROOT_CLK_SEL_UMSK) | (clock << HBN_ROOT_CLK_SEL_POS);
+	sys_write32(tmp, HBN_BASE + HBN_GLB_OFFSET);
+
+	efuse_bflb_clock_settle();
+}
+
+static void efuse_bflb_clock_delay_32M_ms(uint32_t ms)
+{
+	uint32_t count = 0;
+
+	do {
+		__asm__ volatile (".rept 32 ; nop ; .endr");
+		count++;
+	} while (count < ms);
+}
+
+static uint32_t efuse_bflb_is_pds_busy(const struct device *dev)
+{
+	uint32_t tmp;
+	const struct efuse_bflb_config *config = dev->config;
+
+	tmp = sys_read32(config->addr + EF_CTRL_EF_IF_CTRL_0_OFFSET);
+	if (tmp & EF_CTRL_EF_IF_0_BUSY_MSK) {
+		return 1;
+	}
+	return 0;
+}
+
+/* /!\ only use when running on 32Mhz Oscillator Clock
+ * (system_set_root_clock(0);
+ * system_set_root_clock_dividers(0, 0);
+ * sys_write32(32 * 1000 * 1000, CORECLOCKREGISTER);)
+ * Only Use with IRQs off
+ * returns 0 when error
+ */
+static void efuse_bflb_efuse_read(const struct device *dev)
+{
+	const struct efuse_bflb_config *config = dev->config;
+	uint32_t tmp;
+	uint32_t *pefuse_start = (uint32_t *)(config->addr);
+	uint32_t timeout = 0;
+
+	do {
+		efuse_bflb_clock_delay_32M_ms(1);
+		timeout++;
+	} while (timeout < EF_CTRL_DFT_TIMEOUT_VAL && efuse_bflb_is_pds_busy(dev) > 0);
+
+	/* do a 'ahb clock' setup */
+	tmp =	EF_CTRL_EFUSE_CTRL_PROTECT
+		| (EF_CTRL_OP_MODE_AUTO << EF_CTRL_EF_IF_0_MANUAL_EN_POS)
+		| (EF_CTRL_PARA_DFT << EF_CTRL_EF_IF_0_CYC_MODIFY_POS)
+#if defined(CONFIG_SOC_SERIES_BL60X)
+		| (EF_CTRL_SAHB_CLK << EF_CTRL_EF_CLK_SAHB_DATA_SEL_POS)
+#endif
+		| (1 << EF_CTRL_EF_IF_AUTO_RD_EN_POS)
+		| (0 << EF_CTRL_EF_IF_POR_DIG_POS)
+		| (1 << EF_CTRL_EF_IF_0_INT_CLR_POS)
+		| (0 << EF_CTRL_EF_IF_0_RW_POS)
+		| (0 << EF_CTRL_EF_IF_0_TRIG_POS);
+
+	sys_write32(tmp, config->addr + EF_CTRL_EF_IF_CTRL_0_OFFSET);
+	efuse_bflb_clock_settle();
+
+	/* clear PDS cache registry */
+	for (uint32_t i = 0; i < config->size / 4; i++) {
+		pefuse_start[i] = 0;
+	}
+
+	/* Load efuse region0 */
+	/* not ahb clock setup */
+	tmp =	EF_CTRL_EFUSE_CTRL_PROTECT
+		| (EF_CTRL_OP_MODE_AUTO << EF_CTRL_EF_IF_0_MANUAL_EN_POS)
+		| (EF_CTRL_PARA_DFT << EF_CTRL_EF_IF_0_CYC_MODIFY_POS)
+#if defined(CONFIG_SOC_SERIES_BL60X)
+		| (EF_CTRL_EF_CLK << EF_CTRL_EF_CLK_SAHB_DATA_SEL_POS)
+#endif
+		| (1 << EF_CTRL_EF_IF_AUTO_RD_EN_POS)
+		| (0 << EF_CTRL_EF_IF_POR_DIG_POS)
+		| (1 << EF_CTRL_EF_IF_0_INT_CLR_POS)
+		| (0 << EF_CTRL_EF_IF_0_RW_POS)
+		| (0 << EF_CTRL_EF_IF_0_TRIG_POS);
+	sys_write32(tmp, config->addr + EF_CTRL_EF_IF_CTRL_0_OFFSET);
+
+	/* trigger read */
+	tmp =	EF_CTRL_EFUSE_CTRL_PROTECT
+		| (EF_CTRL_OP_MODE_AUTO << EF_CTRL_EF_IF_0_MANUAL_EN_POS)
+		| (EF_CTRL_PARA_DFT << EF_CTRL_EF_IF_0_CYC_MODIFY_POS)
+#if defined(CONFIG_SOC_SERIES_BL60X)
+		| (EF_CTRL_EF_CLK << EF_CTRL_EF_CLK_SAHB_DATA_SEL_POS)
+#endif
+		| (1 << EF_CTRL_EF_IF_AUTO_RD_EN_POS)
+		| (0 << EF_CTRL_EF_IF_POR_DIG_POS)
+		| (1 << EF_CTRL_EF_IF_0_INT_CLR_POS)
+		| (0 << EF_CTRL_EF_IF_0_RW_POS)
+		| (1 << EF_CTRL_EF_IF_0_TRIG_POS);
+	sys_write32(tmp, config->addr + EF_CTRL_EF_IF_CTRL_0_OFFSET);
+	efuse_bflb_clock_delay_32M_ms(5);
+
+	/* wait for read to complete */
+	do {
+		efuse_bflb_clock_delay_32M_ms(1);
+		tmp = sys_read32(config->addr + EF_CTRL_EF_IF_CTRL_0_OFFSET);
+	} while ((tmp & EF_CTRL_EF_IF_0_BUSY_MSK) ||
+		!(tmp & EF_CTRL_EF_IF_0_AUTOLOAD_DONE_MSK));
+
+	/* do a 'ahb clock' setup */
+	tmp =	EF_CTRL_EFUSE_CTRL_PROTECT
+		| (EF_CTRL_OP_MODE_AUTO << EF_CTRL_EF_IF_0_MANUAL_EN_POS)
+		| (EF_CTRL_PARA_DFT << EF_CTRL_EF_IF_0_CYC_MODIFY_POS)
+#if defined(CONFIG_SOC_SERIES_BL60X)
+		| (EF_CTRL_SAHB_CLK << EF_CTRL_EF_CLK_SAHB_DATA_SEL_POS)
+#endif
+		| (1 << EF_CTRL_EF_IF_AUTO_RD_EN_POS)
+		| (0 << EF_CTRL_EF_IF_POR_DIG_POS)
+		| (1 << EF_CTRL_EF_IF_0_INT_CLR_POS)
+		| (0 << EF_CTRL_EF_IF_0_RW_POS)
+		| (0 << EF_CTRL_EF_IF_0_TRIG_POS);
+
+	sys_write32(tmp, config->addr + EF_CTRL_EF_IF_CTRL_0_OFFSET);
+}
+
+static void efuse_bflb_cache(const struct device *dev)
+{
+	struct efuse_bflb_data *data = dev->data;
+	const struct efuse_bflb_config *config = dev->config;
+	uint32_t tmp;
+	uint8_t old_clock_root;
+
+	tmp = sys_read32(HBN_BASE + HBN_GLB_OFFSET);
+	old_clock_root = (tmp & HBN_ROOT_CLK_SEL_MSK) >> HBN_ROOT_CLK_SEL_POS;
+
+	efuse_bflb_set_root_clock(0);
+	efuse_bflb_clock_settle();
+
+	efuse_bflb_efuse_read(dev);
+	/* reads *must* be 32-bits aligned AND does not work with the method memcpy uses */
+	for (int i = 0; i < config->size / sizeof(uint32_t); i++) {
+		tmp = sys_read32(config->addr + i * 4);
+		data->cache[i * sizeof(uint32_t) + 3] = (tmp & 0xFF000000U) >> 24;
+		data->cache[i * sizeof(uint32_t) + 2] = (tmp & 0x00FF0000U) >> 16;
+		data->cache[i * sizeof(uint32_t) + 1] = (tmp & 0x0000FF00U) >> 8;
+		data->cache[i * sizeof(uint32_t) + 0] = (tmp & 0x000000FFU);
+	}
+
+	efuse_bflb_set_root_clock(old_clock_root);
+	efuse_bflb_clock_settle();
+	data->cached = true;
+}
+
+static int efuse_bflb_read(const struct device *dev, uint16_t reg, uint32_t *val)
+{
+	struct efuse_bflb_data *data = dev->data;
+
+	if (!val) {
+		return -EINVAL;
+	}
+
+	if (!data->cached) {
+		efuse_bflb_cache(dev);
+	}
+
+	*val = *((uint32_t *)&data->cache[reg]);
+	return 0;
+}
+
+static int efuse_bflb_size(const struct device *dev, size_t *size)
+{
+	const struct efuse_bflb_config *config = dev->config;
+
+	*size = config->size;
+	return 0;
+}
+
+static int efuse_bflb_get_base(const struct device *dev, uintptr_t *addr)
+{
+	struct efuse_bflb_data *data = dev->data;
+
+	*addr = (uintptr_t)data->cache;
+	return 0;
+}
+
+static DEVICE_API(syscon, efuse_bflb_api) = {
+	.read = efuse_bflb_read,
+	.get_size = efuse_bflb_size,
+	.get_base = efuse_bflb_get_base,
+};
+
+static const struct efuse_bflb_config efuse_config = {
+	.addr = DT_INST_REG_ADDR(0),
+	.size = DT_INST_PROP(0, size),
+};
+
+static struct efuse_bflb_data efuse_data = {
+	.cached = false,
+	.cache = {0},
+};
+
+
+DEVICE_DT_INST_DEFINE(0, NULL, NULL, &efuse_data, &efuse_config, POST_KERNEL,
+		      CONFIG_SYSCON_INIT_PRIORITY, &efuse_bflb_api);

dts/bindings/syscon/bflb,efuse.yaml

@@ -0,0 +1,17 @@
+# Copyright (c) 2024-2025 MASSDRIVER EI (massdriver.space)
+# SPDX-License-Identifier: Apache-2.0
+
+description: BouffaloLab Efuse
+
+compatible: "bflb,efuse"
+
+include: base.yaml
+
+properties:
+  reg:
+    required: true
+
+  size:
+    required: true
+    type: int
+    description: Size of efuse storage (bytes)