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         writeb((arc_console_baud & 0xff00) >> 8, &regs->baudh);
  46
  47         return 0;
  48 }
  49
  50 static int arc_serial_putc(struct udevice *dev, const char c)
  51 {
  52         struct arc_serial_platdata *plat = dev->platdata;
  53         struct arc_serial_regs *const regs = plat->reg;
  54
  55         while (!(readb(&regs->status) & UART_TXEMPTY))
  56                 ;
  57
  58         writeb(c, &regs->data);
  59
  60         return 0;
  61 }
  62
  63 static int arc_serial_tstc(struct arc_serial_regs *const regs)
  64 {
  65         return !(readb(&regs->status) & UART_RXEMPTY);
  66 }
  67
  68 static int arc_serial_pending(struct udevice *dev, bool input)
  69 {
  70         struct arc_serial_platdata *plat = dev->platdata;
  71         struct arc_serial_regs *const regs = plat->reg;
  72         uint32_t status = readb(&regs->status);
  73
  74         if (input)
  75                 return status & UART_RXEMPTY ? 0 : 1;
  76         else
  77                 return status & UART_TXEMPTY ? 0 : 1;
  78 }
  79
  80 static int arc_serial_getc(struct udevice *dev)
  81 {
  82         struct arc_serial_platdata *plat = dev->platdata;
  83         struct arc_serial_regs *const regs = plat->reg;
  84
  85         while (!arc_serial_tstc(regs))
  86                 ;
  87
  88         /* Check for overflow errors */
  89         if (readb(&regs->status) & UART_OVERFLOW_ERR)
  90                 return 0;
  91
  92         return readb(&regs->data) & 0xFF;
  93 }
  94
  95 static int arc_serial_probe(struct udevice *dev)
  96 {
  97         return 0;
  98 }
  99
 100 static const struct dm_serial_ops arc_serial_ops = {
 101         .putc = arc_serial_putc,
 102         .pending = arc_serial_pending,
 103         .getc = arc_serial_getc,
 104         .setbrg = arc_serial_setbrg,
 105 };
 106
 107 static const struct udevice_id arc_serial_ids[] = {
 108         { .compatible = "snps,arc-uart" },
 109         { }
 110 };
 111
 112 static int arc_serial_ofdata_to_platdata(struct udevice *dev)
 113 {
 114         struct arc_serial_platdata *plat = dev_get_platdata(dev);
 115         DECLARE_GLOBAL_DATA_PTR;
 116
 117         plat->reg = (struct arc_serial_regs *)dev_get_addr(dev);
 118         plat->uartclk = fdtdec_get_int(gd->fdt_blob, dev->of_offset,
 119                                        "clock-frequency", 0);
 120
 121         return 0;
 122 }
 123
 124 U_BOOT_DRIVER(serial_arc) = {
 125         .name   = "serial_arc",
 126         .id     = UCLASS_SERIAL,
 127         .of_match = arc_serial_ids,
 128         .ofdata_to_platdata = arc_serial_ofdata_to_platdata,
 129         .probe = arc_serial_probe,
 130         .ops    = &arc_serial_ops,
 131         .flags = DM_FLAG_PRE_RELOC,
 132 };