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 #include <asm/byteorder.h>
14
_write_litex_subregister(u32 val,void __iomem * addr)15 static inline void _write_litex_subregister(u32 val, void __iomem *addr)
16 {
17 writel((u32 __force)cpu_to_le32(val), addr);
18 }
19
_read_litex_subregister(void __iomem * addr)20 static inline u32 _read_litex_subregister(void __iomem *addr)
21 {
22 return le32_to_cpu((__le32 __force)readl(addr));
23 }
24
25 /*
26 * LiteX SoC Generator, depending on the configuration, can split a single
27 * logical CSR (Control&Status Register) into a series of consecutive physical
28 * registers.
29 *
30 * For example, in the configuration with 8-bit CSR Bus, a 32-bit aligned,
31 * 32-bit wide logical CSR will be laid out as four 32-bit physical
32 * subregisters, each one containing one byte of meaningful data.
33 *
34 * For Linux support, upstream LiteX enforces a 32-bit wide CSR bus, which
35 * means that only larger-than-32-bit CSRs will be split across multiple
36 * subregisters (e.g., a 64-bit CSR will be spread across two consecutive
37 * 32-bit subregisters).
38 *
39 * For details see: https://github.com/enjoy-digital/litex/wiki/CSR-Bus
40 */
41
litex_write8(void __iomem * reg,u8 val)42 static inline void litex_write8(void __iomem *reg, u8 val)
43 {
44 _write_litex_subregister(val, reg);
45 }
46
litex_write16(void __iomem * reg,u16 val)47 static inline void litex_write16(void __iomem *reg, u16 val)
48 {
49 _write_litex_subregister(val, reg);
50 }
51
litex_write32(void __iomem * reg,u32 val)52 static inline void litex_write32(void __iomem *reg, u32 val)
53 {
54 _write_litex_subregister(val, reg);
55 }
56
litex_write64(void __iomem * reg,u64 val)57 static inline void litex_write64(void __iomem *reg, u64 val)
58 {
59 _write_litex_subregister(val >> 32, reg);
60 _write_litex_subregister(val, reg + 4);
61 }
62
litex_read8(void __iomem * reg)63 static inline u8 litex_read8(void __iomem *reg)
64 {
65 return _read_litex_subregister(reg);
66 }
67
litex_read16(void __iomem * reg)68 static inline u16 litex_read16(void __iomem *reg)
69 {
70 return _read_litex_subregister(reg);
71 }
72
litex_read32(void __iomem * reg)73 static inline u32 litex_read32(void __iomem *reg)
74 {
75 return _read_litex_subregister(reg);
76 }
77
litex_read64(void __iomem * reg)78 static inline u64 litex_read64(void __iomem *reg)
79 {
80 return ((u64)_read_litex_subregister(reg) << 32) |
81 _read_litex_subregister(reg + 4);
82 }
83
84 #endif /* _LINUX_LITEX_H */
85