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 
_write_litex_subregister(u32 val,void __iomem * addr)14 static inline void _write_litex_subregister(u32 val, void __iomem *addr)
15 {
16 	writel((u32 __force)cpu_to_le32(val), addr);
17 }
18 
_read_litex_subregister(void __iomem * addr)19 static 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 
litex_write8(void __iomem * reg,u8 val)41 static inline void litex_write8(void __iomem *reg, u8 val)
42 {
43 	_write_litex_subregister(val, reg);
44 }
45 
litex_write16(void __iomem * reg,u16 val)46 static inline void litex_write16(void __iomem *reg, u16 val)
47 {
48 	_write_litex_subregister(val, reg);
49 }
50 
litex_write32(void __iomem * reg,u32 val)51 static inline void litex_write32(void __iomem *reg, u32 val)
52 {
53 	_write_litex_subregister(val, reg);
54 }
55 
litex_write64(void __iomem * reg,u64 val)56 static 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 
litex_read8(void __iomem * reg)62 static inline u8 litex_read8(void __iomem *reg)
63 {
64 	return _read_litex_subregister(reg);
65 }
66 
litex_read16(void __iomem * reg)67 static inline u16 litex_read16(void __iomem *reg)
68 {
69 	return _read_litex_subregister(reg);
70 }
71 
litex_read32(void __iomem * reg)72 static inline u32 litex_read32(void __iomem *reg)
73 {
74 	return _read_litex_subregister(reg);
75 }
76 
litex_read64(void __iomem * reg)77 static 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