xref: /openbmc/linux/arch/powerpc/boot/mpc52xx-psc.c (revision 9cfc5c90)
1 /*
2  * MPC5200 PSC serial console support.
3  *
4  * Author: Grant Likely <grant.likely@secretlab.ca>
5  *
6  * Copyright (c) 2007 Secret Lab Technologies Ltd.
7  * Copyright (c) 2007 Freescale Semiconductor, Inc.
8  *
9  * It is assumed that the firmware (or the platform file) has already set
10  * up the port.
11  */
12 
13 #include "types.h"
14 #include "io.h"
15 #include "ops.h"
16 
17 /* Programmable Serial Controller (PSC) status register bits */
18 #define MPC52xx_PSC_SR		0x04
19 #define MPC52xx_PSC_SR_RXRDY		0x0100
20 #define MPC52xx_PSC_SR_RXFULL		0x0200
21 #define MPC52xx_PSC_SR_TXRDY		0x0400
22 #define MPC52xx_PSC_SR_TXEMP		0x0800
23 
24 #define MPC52xx_PSC_BUFFER	0x0C
25 
26 static void *psc;
27 
28 static int psc_open(void)
29 {
30 	/* Assume the firmware has already configured the PSC into
31 	 * uart mode */
32 	return 0;
33 }
34 
35 static void psc_putc(unsigned char c)
36 {
37 	while (!(in_be16(psc + MPC52xx_PSC_SR) & MPC52xx_PSC_SR_TXRDY)) ;
38 	out_8(psc + MPC52xx_PSC_BUFFER, c);
39 }
40 
41 static unsigned char psc_tstc(void)
42 {
43 	return (in_be16(psc + MPC52xx_PSC_SR) & MPC52xx_PSC_SR_RXRDY) != 0;
44 }
45 
46 static unsigned char psc_getc(void)
47 {
48 	while (!(in_be16(psc + MPC52xx_PSC_SR) & MPC52xx_PSC_SR_RXRDY)) ;
49 	return in_8(psc + MPC52xx_PSC_BUFFER);
50 }
51 
52 int mpc5200_psc_console_init(void *devp, struct serial_console_data *scdp)
53 {
54 	/* Get the base address of the psc registers */
55 	if (dt_get_virtual_reg(devp, &psc, 1) < 1)
56 		return -1;
57 
58 	scdp->open = psc_open;
59 	scdp->putc = psc_putc;
60 	scdp->getc = psc_getc;
61 	scdp->tstc = psc_tstc;
62 
63 	return 0;
64 }
65