94b5400e76
This is required for proper functionality on big-endian targets. Memory-mapped registres of ARC UART are not 32-bit words but 8-bit bytes so on little-endian target either acessor (_l or _b) works fine. On big-endian only _b accessors works as expected. Signed-off-by: Alexey Brodkin <abrodkin@synopsys.com> Cc: Vineet Gupta <vgupta@synopsys.com> Cc: Noam Camus <noamc@ezchip.com> Cc: Tom Rini <trini@ti.com>
122 lines
2.5 KiB
C
122 lines
2.5 KiB
C
/*
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* Copyright (C) 2013 Synopsys, Inc. (www.synopsys.com)
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*
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*/
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#include <common.h>
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#include <serial.h>
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DECLARE_GLOBAL_DATA_PTR;
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struct arc_serial_regs {
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unsigned int id0;
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unsigned int id1;
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unsigned int id2;
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unsigned int id3;
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unsigned int data;
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unsigned int status;
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unsigned int baudl;
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unsigned int baudh;
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};
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/* Bit definitions of STATUS register */
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#define UART_RXEMPTY (1 << 5)
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#define UART_OVERFLOW_ERR (1 << 1)
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#define UART_TXEMPTY (1 << 7)
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struct arc_serial_regs *regs;
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static void arc_serial_setbrg(void)
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{
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int arc_console_baud;
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if (!gd->baudrate)
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gd->baudrate = CONFIG_BAUDRATE;
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arc_console_baud = gd->cpu_clk / (gd->baudrate * 4) - 1;
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writeb(arc_console_baud & 0xff, ®s->baudl);
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#ifdef CONFIG_ARC
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/*
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* UART ISS(Instruction Set simulator) emulation has a subtle bug:
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* A existing value of Baudh = 0 is used as a indication to startup
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* it's internal state machine.
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* Thus if baudh is set to 0, 2 times, it chokes.
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* This happens with BAUD=115200 and the formaula above
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* Until that is fixed, when running on ISS, we will set baudh to !0
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*/
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if (gd->arch.running_on_hw)
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writeb((arc_console_baud & 0xff00) >> 8, ®s->baudh);
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else
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writeb(1, ®s->baudh);
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#else
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writeb((arc_console_baud & 0xff00) >> 8, ®s->baudh);
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#endif
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}
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static int arc_serial_init(void)
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{
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regs = (struct arc_serial_regs *)CONFIG_ARC_UART_BASE;
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serial_setbrg();
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return 0;
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}
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static void arc_serial_putc(const char c)
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{
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if (c == '\n')
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arc_serial_putc('\r');
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while (!(readb(®s->status) & UART_TXEMPTY))
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;
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writeb(c, ®s->data);
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}
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static int arc_serial_tstc(void)
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{
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return !(readb(®s->status) & UART_RXEMPTY);
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}
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static int arc_serial_getc(void)
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{
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while (!arc_serial_tstc())
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;
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/* Check for overflow errors */
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if (readb(®s->status) & UART_OVERFLOW_ERR)
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return 0;
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return readb(®s->data) & 0xFF;
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}
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static void arc_serial_puts(const char *s)
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{
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while (*s)
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arc_serial_putc(*s++);
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}
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static struct serial_device arc_serial_drv = {
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.name = "arc_serial",
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.start = arc_serial_init,
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.stop = NULL,
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.setbrg = arc_serial_setbrg,
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.putc = arc_serial_putc,
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.puts = arc_serial_puts,
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.getc = arc_serial_getc,
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.tstc = arc_serial_tstc,
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};
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void arc_serial_initialize(void)
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{
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serial_register(&arc_serial_drv);
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}
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__weak struct serial_device *default_serial_console(void)
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{
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return &arc_serial_drv;
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}
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