[PATCH v2 2/8] generic: Support ARCH_HAS_CPU_CACHE_INVALIDATE_MEMREGION

[Jonathan Cameron]

From: Yicong Yang <yangyicong at hisilicon.com>

ARCH_HAS_CPU_CACHE_INVALIDATE_MEMREGION provides the mechanism for
invalidate certain memory regions in a cache-incoherent manner.
Currently is used by NVIDMM adn CXL memory. This is mainly done
by the system component and is implementation define per spec.
Provides a method for the platforms register their own invalidate
method and implement ARCH_HAS_CPU_CACHE_INVALIDATE_MEMREGION.

Architectures can opt in for this support via
CONFIG_GENERIC_CPU_CACHE_INVALIDATE_MEMREGION.

Signed-off-by: Yicong Yang <yangyicong at hisilicon.com>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron at huawei.com>
---
 drivers/base/Kconfig             |  3 +++
 drivers/base/Makefile            |  1 +
 drivers/base/cache.c             | 46 ++++++++++++++++++++++++++++++++
 include/asm-generic/cacheflush.h | 12 +++++++++
 4 files changed, 62 insertions(+)

diff --git a/drivers/base/Kconfig b/drivers/base/Kconfig
index 064eb52ff7e2..cc6df87a0a96 100644
--- a/drivers/base/Kconfig
+++ b/drivers/base/Kconfig
@@ -181,6 +181,9 @@ config SYS_HYPERVISOR
 	bool
 	default n
 
+config GENERIC_CPU_CACHE_INVALIDATE_MEMREGION
+	bool
+
 config GENERIC_CPU_DEVICES
 	bool
 	default n
diff --git a/drivers/base/Makefile b/drivers/base/Makefile
index 8074a10183dc..0fbfa4300b98 100644
--- a/drivers/base/Makefile
+++ b/drivers/base/Makefile
@@ -26,6 +26,7 @@ obj-$(CONFIG_DEV_COREDUMP) += devcoredump.o
 obj-$(CONFIG_GENERIC_MSI_IRQ) += platform-msi.o
 obj-$(CONFIG_GENERIC_ARCH_TOPOLOGY) += arch_topology.o
 obj-$(CONFIG_GENERIC_ARCH_NUMA) += arch_numa.o
+obj-$(CONFIG_GENERIC_CPU_CACHE_INVALIDATE_MEMREGION) += cache.o
 obj-$(CONFIG_ACPI) += physical_location.o
 
 obj-y			+= test/
diff --git a/drivers/base/cache.c b/drivers/base/cache.c
new file mode 100644
index 000000000000..8d351657bbef
--- /dev/null
+++ b/drivers/base/cache.c
@@ -0,0 +1,46 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Generic support for CPU Cache Invalidate Memregion
+ */
+
+#include <linux/spinlock.h>
+#include <linux/export.h>
+#include <asm/cacheflush.h>
+
+
+static const struct system_cache_flush_method *scfm_data;
+DEFINE_SPINLOCK(scfm_lock);
+
+void generic_set_sys_cache_flush_method(const struct system_cache_flush_method *method)
+{
+	guard(spinlock_irqsave)(&scfm_lock);
+	if (scfm_data || !method || !method->invalidate_memregion)
+		return;
+
+	scfm_data = method;
+}
+EXPORT_SYMBOL_GPL(generic_set_sys_cache_flush_method);
+
+void generic_clr_sys_cache_flush_method(const struct system_cache_flush_method *method)
+{
+	guard(spinlock_irqsave)(&scfm_lock);
+	if (scfm_data && scfm_data == method)
+		scfm_data = NULL;
+}
+
+int cpu_cache_invalidate_memregion(int res_desc, phys_addr_t start, size_t len)
+{
+	guard(spinlock_irqsave)(&scfm_lock);
+	if (!scfm_data)
+		return -EOPNOTSUPP;
+
+	return scfm_data->invalidate_memregion(res_desc, start, len);
+}
+EXPORT_SYMBOL_NS_GPL(cpu_cache_invalidate_memregion, "DEVMEM");
+
+bool cpu_cache_has_invalidate_memregion(void)
+{
+	guard(spinlock_irqsave)(&scfm_lock);
+	return !!scfm_data;
+}
+EXPORT_SYMBOL_NS_GPL(cpu_cache_has_invalidate_memregion, "DEVMEM");
diff --git a/include/asm-generic/cacheflush.h b/include/asm-generic/cacheflush.h
index 7ee8a179d103..87e64295561e 100644
--- a/include/asm-generic/cacheflush.h
+++ b/include/asm-generic/cacheflush.h
@@ -124,4 +124,16 @@ static inline void flush_cache_vunmap(unsigned long start, unsigned long end)
 	} while (0)
 #endif
 
+#ifdef CONFIG_GENERIC_CPU_CACHE_INVALIDATE_MEMREGION
+
+struct system_cache_flush_method {
+	int (*invalidate_memregion)(int res_desc,
+				    phys_addr_t start, size_t len);
+};
+
+void generic_set_sys_cache_flush_method(const struct system_cache_flush_method *method);
+void generic_clr_sys_cache_flush_method(const struct system_cache_flush_method *method);
+
+#endif /* CONFIG_GENERIC_CPU_CACHE_INVALIDATE_MEMREGION */
+
 #endif /* _ASM_GENERIC_CACHEFLUSH_H */
-- 
2.48.1