kernel/arch/powerpc/boot/uartlite.c

   1 /*
   2  * Xilinx UARTLITE bootloader driver
   3  *
   4  * Copyright (C) 2007 Secret Lab Technologies Ltd.
   5  *
   6  * This file is licensed under the terms of the GNU General Public License
   7  * version 2. This program is licensed "as is" without any warranty of any
   8  * kind, whether express or implied.
   9  */
  10
  11 #include <stdarg.h>
  12 #include <stddef.h>
  13 #include "types.h"
  14 #include "string.h"
  15 #include "stdio.h"
  16 #include "io.h"
  17 #include "ops.h"
  18
  19 #define ULITE_RX                0x00
  20 #define ULITE_TX                0x04
  21 #define ULITE_STATUS            0x08
  22 #define ULITE_CONTROL           0x0c
  23
  24 #define ULITE_STATUS_RXVALID    0x01
  25 #define ULITE_STATUS_TXFULL     0x08
  26
  27 #define ULITE_CONTROL_RST_RX    0x02
  28
  29 static void * reg_base;
  30
  31 static int uartlite_open(void)
  32 {
  33         /* Clear the RX FIFO */
  34         out_be32(reg_base + ULITE_CONTROL, ULITE_CONTROL_RST_RX);
  35         return 0;
  36 }
  37
  38 static void uartlite_putc(unsigned char c)
  39 {
  40         u32 reg = ULITE_STATUS_TXFULL;
  41         while (reg & ULITE_STATUS_TXFULL) /* spin on TXFULL bit */
  42                 reg = in_be32(reg_base + ULITE_STATUS);
  43         out_be32(reg_base + ULITE_TX, c);
  44 }
  45
  46 static unsigned char uartlite_getc(void)
  47 {
  48         u32 reg = 0;
  49         while (!(reg & ULITE_STATUS_RXVALID)) /* spin waiting for RXVALID bit */
  50                 reg = in_be32(reg_base + ULITE_STATUS);
  51         return in_be32(reg_base + ULITE_RX);
  52 }
  53
  54 static u8 uartlite_tstc(void)
  55 {
  56         u32 reg = in_be32(reg_base + ULITE_STATUS);
  57         return reg & ULITE_STATUS_RXVALID;
  58 }
  59
  60 int uartlite_console_init(void *devp, struct serial_console_data *scdp)
  61 {
  62         int n;
  63         unsigned long reg_phys;
  64
  65         n = getprop(devp, "virtual-reg", &reg_base, sizeof(reg_base));
  66         if (n != sizeof(reg_base)) {
  67                 if (!dt_xlate_reg(devp, 0, &reg_phys, NULL))
  68                         return -1;
  69
  70                 reg_base = (void *)reg_phys;
  71         }
  72
  73         scdp->open = uartlite_open;
  74         scdp->putc = uartlite_putc;
  75         scdp->getc = uartlite_getc;
  76         scdp->tstc = uartlite_tstc;
  77         scdp->close = NULL;
  78         return 0;
  79 }