root/arch/powerpc/boot/virtex.c

DEFINITIONS

1. virtex_ns16550_console_init
2. platform_specific_init

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * The platform specific code for virtex devices since a boot loader is not
   4  * always used.
   5  *
   6  * (C) Copyright 2008 Xilinx, Inc.
   7  */
   8 
   9 #include "ops.h"
  10 #include "io.h"
  11 #include "stdio.h"
  12 
  13 #define UART_DLL                0       /* Out: Divisor Latch Low */
  14 #define UART_DLM                1       /* Out: Divisor Latch High */
  15 #define UART_FCR                2       /* Out: FIFO Control Register */
  16 #define UART_FCR_CLEAR_RCVR     0x02    /* Clear the RCVR FIFO */
  17 #define UART_FCR_CLEAR_XMIT     0x04    /* Clear the XMIT FIFO */
  18 #define UART_LCR                3       /* Out: Line Control Register */
  19 #define UART_MCR                4       /* Out: Modem Control Register */
  20 #define UART_MCR_RTS            0x02    /* RTS complement */
  21 #define UART_MCR_DTR            0x01    /* DTR complement */
  22 #define UART_LCR_DLAB           0x80    /* Divisor latch access bit */
  23 #define UART_LCR_WLEN8          0x03    /* Wordlength: 8 bits */
  24 
  25 static int virtex_ns16550_console_init(void *devp)
  26 {
  27         unsigned char *reg_base;
  28         u32 reg_shift, reg_offset, clk, spd;
  29         u16 divisor;
  30         int n;
  31 
  32         if (dt_get_virtual_reg(devp, (void **)&reg_base, 1) < 1)
  33                 return -1;
  34 
  35         n = getprop(devp, "reg-offset", &reg_offset, sizeof(reg_offset));
  36         if (n == sizeof(reg_offset))
  37                 reg_base += reg_offset;
  38 
  39         n = getprop(devp, "reg-shift", &reg_shift, sizeof(reg_shift));
  40         if (n != sizeof(reg_shift))
  41                 reg_shift = 0;
  42 
  43         n = getprop(devp, "current-speed", (void *)&spd, sizeof(spd));
  44         if (n != sizeof(spd))
  45                 spd = 9600;
  46 
  47         /* should there be a default clock rate?*/
  48         n = getprop(devp, "clock-frequency", (void *)&clk, sizeof(clk));
  49         if (n != sizeof(clk))
  50                 return -1;
  51 
  52         divisor = clk / (16 * spd);
  53 
  54         /* Access baud rate */
  55         out_8(reg_base + (UART_LCR << reg_shift), UART_LCR_DLAB);
  56 
  57         /* Baud rate based on input clock */
  58         out_8(reg_base + (UART_DLL << reg_shift), divisor & 0xFF);
  59         out_8(reg_base + (UART_DLM << reg_shift), divisor >> 8);
  60 
  61         /* 8 data, 1 stop, no parity */
  62         out_8(reg_base + (UART_LCR << reg_shift), UART_LCR_WLEN8);
  63 
  64         /* RTS/DTR */
  65         out_8(reg_base + (UART_MCR << reg_shift), UART_MCR_RTS | UART_MCR_DTR);
  66 
  67         /* Clear transmitter and receiver */
  68         out_8(reg_base + (UART_FCR << reg_shift),
  69                                 UART_FCR_CLEAR_XMIT | UART_FCR_CLEAR_RCVR);
  70         return 0;
  71 }
  72 
  73 /* For virtex, the kernel may be loaded without using a bootloader and if so
  74    some UARTs need more setup than is provided in the normal console init
  75 */
  76 int platform_specific_init(void)
  77 {
  78         void *devp;
  79         char devtype[MAX_PROP_LEN];
  80         char path[MAX_PATH_LEN];
  81 
  82         devp = finddevice("/chosen");
  83         if (devp == NULL)
  84                 return -1;
  85 
  86         if (getprop(devp, "linux,stdout-path", path, MAX_PATH_LEN) > 0) {
  87                 devp = finddevice(path);
  88                 if (devp == NULL)
  89                         return -1;
  90 
  91                 if ((getprop(devp, "device_type", devtype, sizeof(devtype)) > 0)
  92                                 && !strcmp(devtype, "serial")
  93                                 && (dt_is_compatible(devp, "ns16550")))
  94                                 virtex_ns16550_console_init(devp);
  95         }
  96         return 0;
  97 }