1 // SPDX-License-Identifier: GPL-2.0 2 /* 3 * 16550 serial console support. 4 * 5 * Original copied from <file:arch/ppc/boot/common/ns16550.c> 6 * (which had no copyright) 7 * Modifications: 2006 (c) MontaVista Software, Inc. 8 * 9 * Modified by: Mark A. Greer <mgreer@mvista.com> 10 */ 11 #include <stdarg.h> 12 #include <stddef.h> 13 #include "types.h" 14 #include "string.h" 15 #include "stdio.h" 16 #include "io.h" 17 #include "ops.h" 18 19 #define UART_DLL 0 /* Out: Divisor Latch Low */ 20 #define UART_DLM 1 /* Out: Divisor Latch High */ 21 #define UART_FCR 2 /* Out: FIFO Control Register */ 22 #define UART_LCR 3 /* Out: Line Control Register */ 23 #define UART_MCR 4 /* Out: Modem Control Register */ 24 #define UART_LSR 5 /* In: Line Status Register */ 25 #define UART_LSR_THRE 0x20 /* Transmit-hold-register empty */ 26 #define UART_LSR_DR 0x01 /* Receiver data ready */ 27 #define UART_MSR 6 /* In: Modem Status Register */ 28 #define UART_SCR 7 /* I/O: Scratch Register */ 29 30 static unsigned char *reg_base; 31 static u32 reg_shift; 32 33 static int ns16550_open(void) 34 { 35 out_8(reg_base + (UART_FCR << reg_shift), 0x06); 36 return 0; 37 } 38 39 static void ns16550_putc(unsigned char c) 40 { 41 while ((in_8(reg_base + (UART_LSR << reg_shift)) & UART_LSR_THRE) == 0); 42 out_8(reg_base, c); 43 } 44 45 static unsigned char ns16550_getc(void) 46 { 47 while ((in_8(reg_base + (UART_LSR << reg_shift)) & UART_LSR_DR) == 0); 48 return in_8(reg_base); 49 } 50 51 static u8 ns16550_tstc(void) 52 { 53 return ((in_8(reg_base + (UART_LSR << reg_shift)) & UART_LSR_DR) != 0); 54 } 55 56 int ns16550_console_init(void *devp, struct serial_console_data *scdp) 57 { 58 int n; 59 u32 reg_offset; 60 61 if (dt_get_virtual_reg(devp, (void **)®_base, 1) < 1) 62 return -1; 63 64 n = getprop(devp, "reg-offset", ®_offset, sizeof(reg_offset)); 65 if (n == sizeof(reg_offset)) 66 reg_base += reg_offset; 67 68 n = getprop(devp, "reg-shift", ®_shift, sizeof(reg_shift)); 69 if (n != sizeof(reg_shift)) 70 reg_shift = 0; 71 72 scdp->open = ns16550_open; 73 scdp->putc = ns16550_putc; 74 scdp->getc = ns16550_getc; 75 scdp->tstc = ns16550_tstc; 76 scdp->close = NULL; 77 78 return 0; 79 } 80