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 */ 84