1 // SPDX-License-Identifier: GPL-2.0
3 * 16550 serial console support.
5 * Original copied from <file:arch/ppc/boot/common/ns16550.c>
6 * (which had no copyright)
7 * Modifications: 2006 (c) MontaVista Software, Inc.
9 * Modified by: Mark A. Greer <mgreer@mvista.com>
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 */
30 static unsigned char *reg_base;
33 static int ns16550_open(void)
35 out_8(reg_base + (UART_FCR << reg_shift), 0x06);
39 static void ns16550_putc(unsigned char c)
41 while ((in_8(reg_base + (UART_LSR << reg_shift)) & UART_LSR_THRE) == 0);
45 static unsigned char ns16550_getc(void)
47 while ((in_8(reg_base + (UART_LSR << reg_shift)) & UART_LSR_DR) == 0);
48 return in_8(reg_base);
51 static u8 ns16550_tstc(void)
53 return ((in_8(reg_base + (UART_LSR << reg_shift)) & UART_LSR_DR) != 0);
56 int ns16550_console_init(void *devp, struct serial_console_data *scdp)
61 if (dt_get_virtual_reg(devp, (void **)®_base, 1) < 1)
64 n = getprop(devp, "reg-offset", ®_offset, sizeof(reg_offset));
65 if (n == sizeof(reg_offset))
66 reg_base += reg_offset;
68 n = getprop(devp, "reg-shift", ®_shift, sizeof(reg_shift));
69 if (n != sizeof(reg_shift))
72 scdp->open = ns16550_open;
73 scdp->putc = ns16550_putc;
74 scdp->getc = ns16550_getc;
75 scdp->tstc = ns16550_tstc;