include/linux/litex.h

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