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