drivers/serial_pl011.c

   1 /*
   2  * (C) Copyright 2000
   3  * Rob Taylor, Flying Pig Systems. robt@flyingpig.com.
   4  *
   5  * (C) Copyright 2004
   6  * ARM Ltd.
   7  * Philippe Robin, <philippe.robin@arm.com>
   8  *
   9  * See file CREDITS for list of people who contributed to this
  10  * project.
  11  *
  12  * This program is free software; you can redistribute it and/or
  13  * modify it under the terms of the GNU General Public License as
  14  * published by the Free Software Foundation; either version 2 of
  15  * the License, or (at your option) any later version.
  16  *
  17  * This program is distributed in the hope that it will be useful,
  18  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  19  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  20  * GNU General Public License for more details.
  21  *
  22  * You should have received a copy of the GNU General Public License
  23  * along with this program; if not, write to the Free Software
  24  * Foundation, Inc., 59 Temple Place, Suite 330, Boston,
  25  * MA 02111-1307 USA
  26  */
  27
  28 /* Simple U-Boot driver for the PrimeCell PL011 UARTs on the IntegratorCP */
  29 /* Should be fairly simple to make it work with the PL010 as well */
  30
  31 #include <common.h>
  32
  33 #ifdef CFG_PL011_SERIAL
  34
  35 #include "serial_pl011.h"
  36
  37 #define IO_WRITE(addr, val) (*(volatile unsigned int *)(addr) = (val))
  38 #define IO_READ(addr) (*(volatile unsigned int *)(addr))
  39
  40 /*
  41  * IntegratorCP has two UARTs, use the first one, at 38400-8-N-1
  42  * Versatile PB has four UARTs.
  43  */
  44
  45 #define CONSOLE_PORT CONFIG_CONS_INDEX
  46 #define baudRate CONFIG_BAUDRATE
  47 static volatile unsigned char *const port[] = CONFIG_PL01x_PORTS;
  48 #define NUM_PORTS (sizeof(port)/sizeof(port[0]))
  49
  50 static void pl011_putc (int portnum, char c);
  51 static int pl011_getc (int portnum);
  52 static int pl011_tstc (int portnum);
  53
  54
  55 int serial_init (void)
  56 {
  57         unsigned int temp;
  58         unsigned int divider;
  59         unsigned int remainder;
  60         unsigned int fraction;
  61
  62         /*
  63          ** First, disable everything.
  64          */
  65         IO_WRITE (port[CONSOLE_PORT] + UART_PL011_CR, 0x0);
  66
  67         /*
  68          ** Set baud rate
  69          **
  70          ** IBRD = UART_CLK / (16 * BAUD_RATE)
  71          ** FBRD = ROUND((64 * MOD(UART_CLK,(16 * BAUD_RATE))) / (16 * BAUD_RATE))
  72          */
  73         temp = 16 * baudRate;
  74         divider = CONFIG_PL011_CLOCK / temp;
  75         remainder = CONFIG_PL011_CLOCK % temp;
  76         temp = (8 * remainder) / baudRate;
  77         fraction = (temp >> 1) + (temp & 1);
  78
  79         IO_WRITE (port[CONSOLE_PORT] + UART_PL011_IBRD, divider);
  80         IO_WRITE (port[CONSOLE_PORT] + UART_PL011_FBRD, fraction);
  81
  82         /*
  83          ** Set the UART to be 8 bits, 1 stop bit, no parity, fifo enabled.
  84          */
  85         IO_WRITE (port[CONSOLE_PORT] + UART_PL011_LCRH,
  86                   (UART_PL011_LCRH_WLEN_8 | UART_PL011_LCRH_FEN));
  87
  88         /*
  89          ** Finally, enable the UART
  90          */
  91         IO_WRITE (port[CONSOLE_PORT] + UART_PL011_CR,
  92                   (UART_PL011_CR_UARTEN | UART_PL011_CR_TXE |
  93                    UART_PL011_CR_RXE));
  94
  95         return 0;
  96 }
  97
  98 void serial_putc (const char c)
  99 {
 100         if (c == '\n')
 101                 pl011_putc (CONSOLE_PORT, '\r');
 102
 103         pl011_putc (CONSOLE_PORT, c);
 104 }
 105
 106 void serial_puts (const char *s)
 107 {
 108         while (*s) {
 109                 serial_putc (*s++);
 110         }
 111 }
 112
 113 int serial_getc (void)
 114 {
 115         return pl011_getc (CONSOLE_PORT);
 116 }
 117
 118 int serial_tstc (void)
 119 {
 120         return pl011_tstc (CONSOLE_PORT);
 121 }
 122
 123 void serial_setbrg (void)
 124 {
 125 }
 126
 127 static void pl011_putc (int portnum, char c)
 128 {
 129         /* Wait until there is space in the FIFO */
 130         while (IO_READ (port[portnum] + UART_PL01x_FR) & UART_PL01x_FR_TXFF);
 131
 132         /* Send the character */
 133         IO_WRITE (port[portnum] + UART_PL01x_DR, c);
 134 }
 135
 136 static int pl011_getc (int portnum)
 137 {
 138         unsigned int data;
 139
 140         /* Wait until there is data in the FIFO */
 141         while (IO_READ (port[portnum] + UART_PL01x_FR) & UART_PL01x_FR_RXFE);
 142
 143         data = IO_READ (port[portnum] + UART_PL01x_DR);
 144
 145         /* Check for an error flag */
 146         if (data & 0xFFFFFF00) {
 147                 /* Clear the error */
 148                 IO_WRITE (port[portnum] + UART_PL01x_ECR, 0xFFFFFFFF);
 149                 return -1;
 150         }
 151
 152         return (int) data;
 153 }
 154
 155 static int pl011_tstc (int portnum)
 156 {
 157         return !(IO_READ (port[portnum] + UART_PL01x_FR) &
 158                  UART_PL01x_FR_RXFE);
 159 }
 160
 161 #endif