1 // SPDX-License-Identifier: GPL-2.0-only 2 /* 3 * 4 * Copyright (C) 2011-2012 Gabor Juhos <juhosg@openwrt.org> 5 */ 6 7 #include <linux/io.h> 8 #include <linux/serial_reg.h> 9 10 #include <asm/addrspace.h> 11 #include <asm/setup.h> 12 13 #ifdef CONFIG_SOC_RT288X 14 #define EARLY_UART_BASE 0x300c00 15 #define CHIPID_BASE 0x300004 16 #elif defined(CONFIG_SOC_MT7621) 17 #define EARLY_UART_BASE 0x1E000c00 18 #define CHIPID_BASE 0x1E000004 19 #else 20 #define EARLY_UART_BASE 0x10000c00 21 #define CHIPID_BASE 0x10000004 22 #endif 23 24 #define MT7628_CHIP_NAME1 0x20203832 25 26 #define UART_REG_TX 0x04 27 #define UART_REG_LCR 0x0c 28 #define UART_REG_LSR 0x14 29 #define UART_REG_LSR_RT2880 0x1c 30 31 static __iomem void *uart_membase = (__iomem void *) KSEG1ADDR(EARLY_UART_BASE); 32 static __iomem void *chipid_membase = (__iomem void *) KSEG1ADDR(CHIPID_BASE); 33 static int init_complete; 34 35 static inline void uart_w32(u32 val, unsigned reg) 36 { 37 __raw_writel(val, uart_membase + reg); 38 } 39 40 static inline u32 uart_r32(unsigned reg) 41 { 42 return __raw_readl(uart_membase + reg); 43 } 44 45 static inline int soc_is_mt7628(void) 46 { 47 return IS_ENABLED(CONFIG_SOC_MT7620) && 48 (__raw_readl(chipid_membase) == MT7628_CHIP_NAME1); 49 } 50 51 static void find_uart_base(void) 52 { 53 int i; 54 55 if (!soc_is_mt7628()) 56 return; 57 58 for (i = 0; i < 3; i++) { 59 u32 reg = uart_r32(UART_REG_LCR + (0x100 * i)); 60 61 if (!reg) 62 continue; 63 64 uart_membase = (__iomem void *) KSEG1ADDR(EARLY_UART_BASE + 65 (0x100 * i)); 66 break; 67 } 68 } 69 70 void prom_putchar(char ch) 71 { 72 if (!init_complete) { 73 find_uart_base(); 74 init_complete = 1; 75 } 76 77 if (IS_ENABLED(CONFIG_SOC_MT7621) || soc_is_mt7628()) { 78 uart_w32((unsigned char)ch, UART_TX); 79 while ((uart_r32(UART_REG_LSR) & UART_LSR_THRE) == 0) 80 ; 81 } else { 82 while ((uart_r32(UART_REG_LSR_RT2880) & UART_LSR_THRE) == 0) 83 ; 84 uart_w32((unsigned char)ch, UART_REG_TX); 85 while ((uart_r32(UART_REG_LSR_RT2880) & UART_LSR_THRE) == 0) 86 ; 87 } 88 } 89