1/* SPDX-License-Identifier: GPL-2.0 */
2/*
3 * Common LiteX header providing
4 * helper functions for accessing CSRs.
5 *
6 * Copyright (C) 2019-2020 Antmicro <www.antmicro.com>
7 */
8
9#ifndef _LINUX_LITEX_H
10#define _LINUX_LITEX_H
11
12#include <linux/io.h>
13
14static inline void _write_litex_subregister(u32 val, void __iomem *addr)
15{
16	writel((u32 __force)cpu_to_le32(val), addr);
17}
18
19static inline u32 _read_litex_subregister(void __iomem *addr)
20{
21	return le32_to_cpu((__le32 __force)readl(addr));
22}
23
24/*
25 * LiteX SoC Generator, depending on the configuration, can split a single
26 * logical CSR (Control&Status Register) into a series of consecutive physical
27 * registers.
28 *
29 * For example, in the configuration with 8-bit CSR Bus, a 32-bit aligned,
30 * 32-bit wide logical CSR will be laid out as four 32-bit physical
31 * subregisters, each one containing one byte of meaningful data.
32 *
33 * For Linux support, upstream LiteX enforces a 32-bit wide CSR bus, which
34 * means that only larger-than-32-bit CSRs will be split across multiple
35 * subregisters (e.g., a 64-bit CSR will be spread across two consecutive
36 * 32-bit subregisters).
37 *
38 * For details see: https://github.com/enjoy-digital/litex/wiki/CSR-Bus
39 */
40
41static inline void litex_write8(void __iomem *reg, u8 val)
42{
43	_write_litex_subregister(val, reg);
44}
45
46static inline void litex_write16(void __iomem *reg, u16 val)
47{
48	_write_litex_subregister(val, reg);
49}
50
51static inline void litex_write32(void __iomem *reg, u32 val)
52{
53	_write_litex_subregister(val, reg);
54}
55
56static inline void litex_write64(void __iomem *reg, u64 val)
57{
58	_write_litex_subregister(val >> 32, reg);
59	_write_litex_subregister(val, reg + 4);
60}
61
62static inline u8 litex_read8(void __iomem *reg)
63{
64	return _read_litex_subregister(reg);
65}
66
67static inline u16 litex_read16(void __iomem *reg)
68{
69	return _read_litex_subregister(reg);
70}
71
72static inline u32 litex_read32(void __iomem *reg)
73{
74	return _read_litex_subregister(reg);
75}
76
77static inline u64 litex_read64(void __iomem *reg)
78{
79	return ((u64)_read_litex_subregister(reg) << 32) |
80		_read_litex_subregister(reg + 4);
81}
82
83#endif /* _LINUX_LITEX_H */
84