[RFC PATCH 16/47] lkl tools: host lib: memory mapped I/O helpers

[Hajime Tazaki <thehajime@gmail.com>]

From: Octavian Purdila <tavi.purdila@gmail.com>

This patch adds helpers for implementing the memory mapped I/O host
operations that can be used by code that implements host
devices. Generic host operations for lkl_ioremap and lkl_iomem_access
are provided that allows multiplexing multiple I/O memory mapped
regions.

The host device code can create a new memory mapped I/O region with
register_iomem(). Read and write access functions need to be provided
by the caller.

Signed-off-by: Octavian Purdila <tavi.purdila@gmail.com>
---
 tools/lkl/lib/iomem.c | 88 +++++++++++++++++++++++++++++++++++++++++++
 tools/lkl/lib/iomem.h | 15 ++++++++
 2 files changed, 103 insertions(+)
 create mode 100644 tools/lkl/lib/iomem.c
 create mode 100644 tools/lkl/lib/iomem.h

diff --git a/tools/lkl/lib/iomem.c b/tools/lkl/lib/iomem.c
new file mode 100644
index 000000000000..2301fe4e5ad5
--- /dev/null
+++ b/tools/lkl/lib/iomem.c
@@ -0,0 +1,88 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <string.h>
+#include <stdint.h>
+#include <lkl_host.h>
+
+#include "iomem.h"
+
+#define IOMEM_OFFSET_BITS		24
+#define MAX_IOMEM_REGIONS		256
+
+#define IOMEM_ADDR_TO_INDEX(addr) \
+	(((uintptr_t)addr) >> IOMEM_OFFSET_BITS)
+#define IOMEM_ADDR_TO_OFFSET(addr) \
+	(((uintptr_t)addr) & ((1 << IOMEM_OFFSET_BITS) - 1))
+#define IOMEM_INDEX_TO_ADDR(i) \
+	(void *)(uintptr_t)(i << IOMEM_OFFSET_BITS)
+
+static struct iomem_region {
+	void *data;
+	int size;
+	const struct lkl_iomem_ops *ops;
+} iomem_regions[MAX_IOMEM_REGIONS];
+
+void *register_iomem(void *data, int size, const struct lkl_iomem_ops *ops)
+{
+	int i;
+
+	if (size > (1 << IOMEM_OFFSET_BITS) - 1)
+		return NULL;
+
+	for (i = 1; i < MAX_IOMEM_REGIONS; i++)
+		if (!iomem_regions[i].ops)
+			break;
+
+	if (i >= MAX_IOMEM_REGIONS)
+		return NULL;
+
+	iomem_regions[i].data = data;
+	iomem_regions[i].size = size;
+	iomem_regions[i].ops = ops;
+	return IOMEM_INDEX_TO_ADDR(i);
+}
+
+void unregister_iomem(void *base)
+{
+	unsigned int index = IOMEM_ADDR_TO_INDEX(base);
+
+	if (index >= MAX_IOMEM_REGIONS) {
+		lkl_printf("%s: invalid iomem_addr %p\n", __func__, base);
+		return;
+	}
+
+	iomem_regions[index].size = 0;
+	iomem_regions[index].ops = NULL;
+}
+
+void *lkl_ioremap(long addr, int size)
+{
+	int index = IOMEM_ADDR_TO_INDEX(addr);
+	struct iomem_region *iomem = &iomem_regions[index];
+
+	if (index >= MAX_IOMEM_REGIONS)
+		return NULL;
+
+	if (iomem->ops && size <= iomem->size)
+		return IOMEM_INDEX_TO_ADDR(index);
+
+	return NULL;
+}
+
+int lkl_iomem_access(const volatile void *addr, void *res, int size, int write)
+{
+	int index = IOMEM_ADDR_TO_INDEX(addr);
+	struct iomem_region *iomem = &iomem_regions[index];
+	int offset = IOMEM_ADDR_TO_OFFSET(addr);
+	int ret;
+
+	if (index > MAX_IOMEM_REGIONS || !iomem_regions[index].ops ||
+	    offset + size > iomem_regions[index].size)
+		return -1;
+
+	if (write)
+		ret = iomem->ops->write(iomem->data, offset, res, size);
+	else
+		ret = iomem->ops->read(iomem->data, offset, res, size);
+
+	return ret;
+}
diff --git a/tools/lkl/lib/iomem.h b/tools/lkl/lib/iomem.h
new file mode 100644
index 000000000000..0ad80ccc2626
--- /dev/null
+++ b/tools/lkl/lib/iomem.h
@@ -0,0 +1,15 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _LKL_LIB_IOMEM_H
+#define _LKL_LIB_IOMEM_H
+
+struct lkl_iomem_ops {
+	int (*read)(void *data, int offset, void *res, int size);
+	int (*write)(void *data, int offset, void *value, int size);
+};
+
+void *register_iomem(void *data, int size, const struct lkl_iomem_ops *ops);
+void unregister_iomem(void *iomem_base);
+void *lkl_ioremap(long addr, int size);
+int lkl_iomem_access(const volatile void *addr, void *res, int size, int write);
+
+#endif /* _LKL_LIB_IOMEM_H */
-- 
2.20.1 (Apple Git-117)


_______________________________________________
linux-um mailing list
linux-um@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-um