1 files changed, 83 insertions, 0 deletions
diff --git a/include/linux/litex.h b/include/linux/litex.h
new file mode 100644
index 000000000000..f2edb86d5f44
--- /dev/null
+++ b/include/linux/litex.h
@@ -0,0 +1,83 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Common LiteX header providing
+ * helper functions for accessing CSRs.
+ *
+ * Copyright (C) 2019-2020 Antmicro <www.antmicro.com>
+ */
+
+#ifndef _LINUX_LITEX_H
+#define _LINUX_LITEX_H
+
+#include <linux/io.h>
+
+static inline void _write_litex_subregister(u32 val, void __iomem *addr)
+{
+	writel((u32 __force)cpu_to_le32(val), addr);
+}
+
+static inline u32 _read_litex_subregister(void __iomem *addr)
+{
+	return le32_to_cpu((__le32 __force)readl(addr));
+}
+
+/*
+ * LiteX SoC Generator, depending on the configuration, can split a single
+ * logical CSR (Control&Status Register) into a series of consecutive physical
+ * registers.
+ *
+ * For example, in the configuration with 8-bit CSR Bus, a 32-bit aligned,
+ * 32-bit wide logical CSR will be laid out as four 32-bit physical
+ * subregisters, each one containing one byte of meaningful data.
+ *
+ * For Linux support, upstream LiteX enforces a 32-bit wide CSR bus, which
+ * means that only larger-than-32-bit CSRs will be split across multiple
+ * subregisters (e.g., a 64-bit CSR will be spread across two consecutive
+ * 32-bit subregisters).
+ *
+ * For details see: https://github.com/enjoy-digital/litex/wiki/CSR-Bus
+ */
+
+static inline void litex_write8(void __iomem *reg, u8 val)
+{
+	_write_litex_subregister(val, reg);
+}
+
+static inline void litex_write16(void __iomem *reg, u16 val)
+{
+	_write_litex_subregister(val, reg);
+}
+
+static inline void litex_write32(void __iomem *reg, u32 val)
+{
+	_write_litex_subregister(val, reg);
+}
+
+static inline void litex_write64(void __iomem *reg, u64 val)
+{
+	_write_litex_subregister(val >> 32, reg);
+	_write_litex_subregister(val, reg + 4);
+}
+
+static inline u8 litex_read8(void __iomem *reg)
+{
+	return _read_litex_subregister(reg);
+}
+
+static inline u16 litex_read16(void __iomem *reg)
+{
+	return _read_litex_subregister(reg);
+}
+
+static inline u32 litex_read32(void __iomem *reg)
+{
+	return _read_litex_subregister(reg);
+}
+
+static inline u64 litex_read64(void __iomem *reg)
+{
+	return ((u64)_read_litex_subregister(reg) << 32) |
+		_read_litex_subregister(reg + 4);
+}
+
+#endif /* _LINUX_LITEX_H */