xref: /openbmc/linux/arch/powerpc/boot/mpc52xx-psc.c (revision b2441318)
1 // SPDX-License-Identifier: GPL-2.0
2 /*
3  * MPC5200 PSC serial console support.
4  *
5  * Author: Grant Likely <grant.likely@secretlab.ca>
6  *
7  * Copyright (c) 2007 Secret Lab Technologies Ltd.
8  * Copyright (c) 2007 Freescale Semiconductor, Inc.
9  *
10  * It is assumed that the firmware (or the platform file) has already set
11  * up the port.
12  */
13 
14 #include "types.h"
15 #include "io.h"
16 #include "ops.h"
17 
18 /* Programmable Serial Controller (PSC) status register bits */
19 #define MPC52xx_PSC_SR		0x04
20 #define MPC52xx_PSC_SR_RXRDY		0x0100
21 #define MPC52xx_PSC_SR_RXFULL		0x0200
22 #define MPC52xx_PSC_SR_TXRDY		0x0400
23 #define MPC52xx_PSC_SR_TXEMP		0x0800
24 
25 #define MPC52xx_PSC_BUFFER	0x0C
26 
27 static void *psc;
28 
psc_open(void)29 static int psc_open(void)
30 {
31 	/* Assume the firmware has already configured the PSC into
32 	 * uart mode */
33 	return 0;
34 }
35 
psc_putc(unsigned char c)36 static void psc_putc(unsigned char c)
37 {
38 	while (!(in_be16(psc + MPC52xx_PSC_SR) & MPC52xx_PSC_SR_TXRDY)) ;
39 	out_8(psc + MPC52xx_PSC_BUFFER, c);
40 }
41 
psc_tstc(void)42 static unsigned char psc_tstc(void)
43 {
44 	return (in_be16(psc + MPC52xx_PSC_SR) & MPC52xx_PSC_SR_RXRDY) != 0;
45 }
46 
psc_getc(void)47 static unsigned char psc_getc(void)
48 {
49 	while (!(in_be16(psc + MPC52xx_PSC_SR) & MPC52xx_PSC_SR_RXRDY)) ;
50 	return in_8(psc + MPC52xx_PSC_BUFFER);
51 }
52 
mpc5200_psc_console_init(void * devp,struct serial_console_data * scdp)53 int mpc5200_psc_console_init(void *devp, struct serial_console_data *scdp)
54 {
55 	/* Get the base address of the psc registers */
56 	if (dt_get_virtual_reg(devp, &psc, 1) < 1)
57 		return -1;
58 
59 	scdp->open = psc_open;
60 	scdp->putc = psc_putc;
61 	scdp->getc = psc_getc;
62 	scdp->tstc = psc_tstc;
63 
64 	return 0;
65 }
66