cache: stm32: add cortex-m33 peripheral driver

STM32 Cortex-M33, such as the L5/H5/U5 series, have a cache peripheral for
instruction and data caches, which are not present in the C-M33
architecture spec.

The driver defaults to direct mapped cache as it uses less power than the
alternative set associative mapping [1]. This has also been the default in
stm32 soc initialization code for chips that have the ICACHE peripheral,
which makes it the safest choice for backward compatibility. The exception
to the rule is STM32L5, which has the n-way cache mode selected in SOC
code.

[1]: https://en.wikipedia.org/wiki/Cache_placement_policies

Signed-off-by: Henrik Lindblom <[email protected]>

Author: Henrik Lindblom

drivers/cache/CMakeLists.txt

@@ -10,3 +10,4 @@ zephyr_library_sources_ifdef(CONFIG_CACHE_ANDES 	cache_andes.c)
 zephyr_library_sources_ifdef(CONFIG_USERSPACE		cache_handlers.c)
 zephyr_library_sources_ifdef(CONFIG_CACHE_NRF_CACHE	cache_nrf.c)
 zephyr_library_sources_ifdef(CONFIG_CACHE_NXP_XCACHE	cache_nxp_xcache.c)
+zephyr_library_sources_ifdef(CONFIG_CACHE_STM32	cache_stm32.c)

drivers/cache/Kconfig

@@ -22,5 +22,6 @@ source "drivers/cache/Kconfig.aspeed"
 source "drivers/cache/Kconfig.nrf"
 source "drivers/cache/Kconfig.andes"
 source "drivers/cache/Kconfig.nxp_xcache"
+source "drivers/cache/Kconfig.stm32"
 
 endif # CACHE

drivers/cache/Kconfig.stm32

@@ -0,0 +1,24 @@
+# Copyright (c) 2025 Henrik Lindblom <[email protected]>
+# SPDX-License-Identifier: Apache-2.0
+
+menuconfig CACHE_STM32
+	bool "STM32 cache driver"
+	select CACHE_HAS_DRIVER
+	depends on CACHE_MANAGEMENT
+	help
+	  Enable support for the STM32 ICACHE / DCACHE peripheral present in some STM32 chips.
+
+if CACHE_STM32
+
+# "default n" for L5 is legacy - could be removed?
+config CACHE_STM32_ICACHE_DIRECT_MAPPING
+	bool "Use 1-way associative mapping for ICACHE"
+	default n if SOC_SERIES_STM32L5X
+	default y
+	help
+	  Use ICACHE in direct mapping (1-way associative) mode instead of the default n-way
+	  associative cache mode.
+
+	  This option reduces power consumption but slightly reduces cache's performance.
+
+endif # CACHE_STM32

drivers/cache/cache_stm32.c

@@ -0,0 +1,182 @@
+/*
+ * Copyright (c) 2025 Henrik Lindblom <[email protected]>
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+#include <zephyr/kernel.h>
+#include <zephyr/drivers/cache.h>
+#include <zephyr/logging/log.h>
+#include <zephyr/sys/math_extras.h>
+#include <stm32_ll_dcache.h>
+#include <stm32_ll_icache.h>
+
+LOG_MODULE_REGISTER(cache_stm32, CONFIG_CACHE_LOG_LEVEL);
+
+#ifdef CONFIG_DCACHE
+
+void cache_data_enable(void)
+{
+	LL_DCACHE_Enable(DCACHE1);
+#if defined(DCACHE2)
+	LL_DCACHE_Enable(DCACHE2);
+#endif
+}
+
+void cache_data_disable(void)
+{
+	cache_data_flush_all();
+
+	while (LL_DCACHE_IsActiveFlag_BUSYCMD(DCACHE1)) {
+	}
+
+	LL_DCACHE_Disable(DCACHE1);
+	LL_DCACHE_ClearFlag_BSYEND(DCACHE1);
+
+#if defined(DCACHE2)
+	while (LL_DCACHE_IsActiveFlag_BUSYCMD(DCACHE2)) {
+	}
+
+	LL_DCACHE_Disable(DCACHE2);
+	LL_DCACHE_ClearFlag_BSYEND(DCACHE2);
+#endif
+}
+
+static int cache_data_manage_range(void *addr, size_t size, uint32_t command)
+{
+	/*
+	 * This is a simple approach to invalidate the range. The address might be in either DCACHE1
+	 * or DCACHE2 (if present). The cache invalidation algorithm checks the TAG memory for the
+	 * specified address range so there's little harm in just checking both caches.
+	 */
+	uint32_t start = (uint32_t)addr;
+	uint32_t end;
+
+	if (u32_add_overflow(start, size, &end)) {
+		return -EOVERFLOW;
+	}
+
+	LL_DCACHE_SetStartAddress(DCACHE1, start);
+	LL_DCACHE_SetEndAddress(DCACHE1, end);
+	LL_DCACHE_SetCommand(DCACHE1, command);
+	LL_DCACHE_StartCommand(DCACHE1);
+#if defined(DCACHE2)
+	LL_DCACHE_SetStartAddress(DCACHE2, start);
+	LL_DCACHE_SetEndAddress(DCACHE2, end);
+	LL_DCACHE_SetCommand(DCACHE2, command);
+	LL_DCACHE_StartCommand(DCACHE2);
+#endif
+	return 0;
+}
+
+int cache_data_flush_range(void *addr, size_t size)
+{
+	return cache_data_manage_range(addr, size, LL_DCACHE_COMMAND_CLEAN_BY_ADDR);
+}
+
+int cache_data_invd_range(void *addr, size_t size)
+{
+	return cache_data_manage_range(addr, size, LL_DCACHE_COMMAND_INVALIDATE_BY_ADDR);
+}
+
+int cache_data_flush_and_invd_range(void *addr, size_t size)
+{
+	return cache_data_manage_range(addr, size, LL_DCACHE_COMMAND_CLEAN_INVALIDATE_BY_ADDR);
+}
+
+int cache_data_flush_all(void)
+{
+	return cache_data_flush_range(0, UINT32_MAX);
+}
+
+int cache_data_invd_all(void)
+{
+	LL_DCACHE_Invalidate(DCACHE1);
+#if defined(DCACHE2)
+	LL_DCACHE_Invalidate(DCACHE2);
+#endif
+	return 0;
+}
+
+int cache_data_flush_and_invd_all(void)
+{
+	return cache_data_flush_and_invd_range(0, UINT32_MAX);
+}
+
+#endif /* CONFIG_DCACHE */
+
+static inline void wait_for_icache(void)
+{
+	while (LL_ICACHE_IsActiveFlag_BUSY()) {
+	}
+
+	/* Clear BSYEND to avoid an extra interrupt if somebody enables them. */
+	LL_ICACHE_ClearFlag_BSYEND();
+}
+
+void cache_instr_enable(void)
+{
+	if (IS_ENABLED(CONFIG_CACHE_STM32_ICACHE_DIRECT_MAPPING)) {
+		LL_ICACHE_SetMode(LL_ICACHE_1WAY);
+	}
+
+	/*
+	 * Need to wait until any pending cache invalidation operations finish. This is recommended
+	 * in the reference manual to ensure execution timing determinism.
+	 */
+	wait_for_icache();
+	LL_ICACHE_Enable();
+}
+
+void cache_instr_disable(void)
+{
+	LL_ICACHE_Disable();
+
+	while (LL_ICACHE_IsEnabled()) {
+		/**
+		 * Wait until the ICACHE is disabled (CR.EN=0), at which point
+		 * all requests bypass the cache and are forwarded directly
+		 * from the ICACHE slave port to the ICACHE master port(s).
+		 *
+		 * The cache invalidation will start once disabled, but we allow
+		 * it to proceed in the background since it doesn't need to be
+		 * complete for requests to bypass the ICACHE.
+		 */
+	}
+}
+
+int cache_instr_flush_all(void)
+{
+	return -ENOTSUP;
+}
+
+int cache_instr_invd_all(void)
+{
+	LL_ICACHE_Invalidate();
+	return 0;
+}
+
+int cache_instr_flush_and_invd_all(void)
+{
+	return -ENOTSUP;
+}
+
+int cache_instr_flush_range(void *addr, size_t size)
+{
+	ARG_UNUSED(addr);
+	ARG_UNUSED(size);
+	return -ENOTSUP;
+}
+
+int cache_instr_invd_range(void *addr, size_t size)
+{
+	ARG_UNUSED(addr);
+	ARG_UNUSED(size);
+	return -ENOTSUP;
+}
+
+int cache_instr_flush_and_invd_range(void *addr, size_t size)
+{
+	ARG_UNUSED(addr);
+	ARG_UNUSED(size);
+	return -ENOTSUP;
+}