powerpc/boot/ns16550.c

0001 // SPDX-License-Identifier: GPL-2.0
0002 /*
0003  * 16550 serial console support.
0004  *
0005  * Original copied from <file:arch/ppc/boot/common/ns16550.c>
0006  * (which had no copyright)
0007  * Modifications: 2006 (c) MontaVista Software, Inc.
0008  *
0009  * Modified by: Mark A. Greer <mgreer@mvista.com>
0010  */
0011 #include <stdarg.h>
0012 #include <stddef.h>
0013 #include "types.h"
0014 #include "string.h"
0015 #include "stdio.h"
0016 #include "io.h"
0017 #include "ops.h"
0018 #include "of.h"
0019
0020 #define UART_DLL    0   /* Out: Divisor Latch Low */
0021 #define UART_DLM    1   /* Out: Divisor Latch High */
0022 #define UART_FCR    2   /* Out: FIFO Control Register */
0023 #define UART_LCR    3   /* Out: Line Control Register */
0024 #define UART_MCR    4   /* Out: Modem Control Register */
0025 #define UART_LSR    5   /* In:  Line Status Register */
0026 #define UART_LSR_THRE   0x20    /* Transmit-hold-register empty */
0027 #define UART_LSR_DR 0x01    /* Receiver data ready */
0028 #define UART_MSR    6   /* In:  Modem Status Register */
0029 #define UART_SCR    7   /* I/O: Scratch Register */
0030
0031 static unsigned char *reg_base;
0032 static u32 reg_shift;
0033
0034 static int ns16550_open(void)
0035 {
0036     out_8(reg_base + (UART_FCR << reg_shift), 0x06);
0037     return 0;
0038 }
0039
0040 static void ns16550_putc(unsigned char c)
0041 {
0042     while ((in_8(reg_base + (UART_LSR << reg_shift)) & UART_LSR_THRE) == 0);
0043     out_8(reg_base, c);
0044 }
0045
0046 static unsigned char ns16550_getc(void)
0047 {
0048     while ((in_8(reg_base + (UART_LSR << reg_shift)) & UART_LSR_DR) == 0);
0049     return in_8(reg_base);
0050 }
0051
0052 static u8 ns16550_tstc(void)
0053 {
0054     return ((in_8(reg_base + (UART_LSR << reg_shift)) & UART_LSR_DR) != 0);
0055 }
0056
0057 int ns16550_console_init(void *devp, struct serial_console_data *scdp)
0058 {
0059     int n;
0060     u32 reg_offset;
0061
0062     if (dt_get_virtual_reg(devp, (void **)&reg_base, 1) < 1) {
0063         printf("virt reg parse fail...\r\n");
0064         return -1;
0065     }
0066
0067     n = getprop(devp, "reg-offset", &reg_offset, sizeof(reg_offset));
0068     if (n == sizeof(reg_offset))
0069         reg_base += be32_to_cpu(reg_offset);
0070
0071     n = getprop(devp, "reg-shift", &reg_shift, sizeof(reg_shift));
0072     if (n != sizeof(reg_shift))
0073         reg_shift = 0;
0074     else
0075         reg_shift = be32_to_cpu(reg_shift);
0076
0077     scdp->open = ns16550_open;
0078     scdp->putc = ns16550_putc;
0079     scdp->getc = ns16550_getc;
0080     scdp->tstc = ns16550_tstc;
0081     scdp->close = NULL;
0082
0083     return 0;
0084 }