drivers/serial/serial_arc.c

   1 /*
   2  * Copyright (C) 2013 Synopsys, Inc. (www.synopsys.com)
   3  *
   4  * This program is free software; you can redistribute it and/or modify
   5  * it under the terms of the GNU General Public License version 2 as
   6  * published by the Free Software Foundation.
   7  *
   8  */
   9
  10 #include <common.h>
  11 #include <dm.h>
  12 #include <serial.h>
  13
  14 DECLARE_GLOBAL_DATA_PTR;
  15
  16 struct arc_serial_regs {
  17         unsigned int id0;
  18         unsigned int id1;
  19         unsigned int id2;
  20         unsigned int id3;
  21         unsigned int data;
  22         unsigned int status;
  23         unsigned int baudl;
  24         unsigned int baudh;
  25 };
  26
  27
  28 struct arc_serial_platdata {
  29         struct arc_serial_regs *reg;
  30         unsigned int uartclk;
  31 };
  32
  33 /* Bit definitions of STATUS register */
  34 #define UART_RXEMPTY            (1 << 5)
  35 #define UART_OVERFLOW_ERR       (1 << 1)
  36 #define UART_TXEMPTY            (1 << 7)
  37
  38 static int arc_serial_setbrg(struct udevice *dev, int baudrate)
  39 {
  40         struct arc_serial_platdata *plat = dev->platdata;
  41         struct arc_serial_regs *const regs = plat->reg;
  42         int arc_console_baud = gd->cpu_clk / (baudrate * 4) - 1;
  43
  44         writeb(arc_console_baud & 0xff, &regs->baudl);
  45
  46 #ifdef CONFIG_ARC
  47         /*
  48          * UART ISS(Instruction Set simulator) emulation has a subtle bug:
  49          * A existing value of Baudh = 0 is used as a indication to startup
  50          * it's internal state machine.
  51          * Thus if baudh is set to 0, 2 times, it chokes.
  52          * This happens with BAUD=115200 and the formaula above
  53          * Until that is fixed, when running on ISS, we will set baudh to !0
  54          */
  55         if (gd->arch.running_on_hw)
  56                 writeb((arc_console_baud & 0xff00) >> 8, &regs->baudh);
  57         else
  58                 writeb(1, &regs->baudh);
  59 #else
  60         writeb((arc_console_baud & 0xff00) >> 8, &regs->baudh);
  61 #endif
  62
  63         return 0;
  64 }
  65
  66 static int arc_serial_putc(struct udevice *dev, const char c)
  67 {
  68         struct arc_serial_platdata *plat = dev->platdata;
  69         struct arc_serial_regs *const regs = plat->reg;
  70
  71         while (!(readb(&regs->status) & UART_TXEMPTY))
  72                 ;
  73
  74         writeb(c, &regs->data);
  75
  76         return 0;
  77 }
  78
  79 static int arc_serial_tstc(struct arc_serial_regs *const regs)
  80 {
  81         return !(readb(&regs->status) & UART_RXEMPTY);
  82 }
  83
  84 static int arc_serial_pending(struct udevice *dev, bool input)
  85 {
  86         struct arc_serial_platdata *plat = dev->platdata;
  87         struct arc_serial_regs *const regs = plat->reg;
  88         uint32_t status = readb(&regs->status);
  89
  90         if (input)
  91                 return status & UART_RXEMPTY ? 0 : 1;
  92         else
  93                 return status & UART_TXEMPTY ? 0 : 1;
  94 }
  95
  96 static int arc_serial_getc(struct udevice *dev)
  97 {
  98         struct arc_serial_platdata *plat = dev->platdata;
  99         struct arc_serial_regs *const regs = plat->reg;
 100
 101         while (!arc_serial_tstc(regs))
 102                 ;
 103
 104         /* Check for overflow errors */
 105         if (readb(&regs->status) & UART_OVERFLOW_ERR)
 106                 return 0;
 107
 108         return readb(&regs->data) & 0xFF;
 109 }
 110
 111 static int arc_serial_probe(struct udevice *dev)
 112 {
 113         return 0;
 114 }
 115
 116 static const struct dm_serial_ops arc_serial_ops = {
 117         .putc = arc_serial_putc,
 118         .pending = arc_serial_pending,
 119         .getc = arc_serial_getc,
 120         .setbrg = arc_serial_setbrg,
 121 };
 122
 123 static const struct udevice_id arc_serial_ids[] = {
 124         { .compatible = "snps,arc-uart" },
 125         { }
 126 };
 127
 128 static int arc_serial_ofdata_to_platdata(struct udevice *dev)
 129 {
 130         struct arc_serial_platdata *plat = dev_get_platdata(dev);
 131         DECLARE_GLOBAL_DATA_PTR;
 132
 133         plat->reg = (struct arc_serial_regs *)dev_get_addr(dev);
 134         plat->uartclk = fdtdec_get_int(gd->fdt_blob, dev->of_offset,
 135                                        "clock-frequency", 0);
 136
 137         return 0;
 138 }
 139
 140 U_BOOT_DRIVER(serial_arc) = {
 141         .name   = "serial_arc",
 142         .id     = UCLASS_SERIAL,
 143         .of_match = arc_serial_ids,
 144         .ofdata_to_platdata = arc_serial_ofdata_to_platdata,
 145         .probe = arc_serial_probe,
 146         .ops    = &arc_serial_ops,
 147         .flags = DM_FLAG_PRE_RELOC,
 148 };