drivers/serial/atmel_usart.c

   1 /*
   2  * Copyright (C) 2004-2006 Atmel Corporation
   3  *
   4  * Modified to support C structur SoC access by
   5  * Andreas Bießmann <biessmann@corscience.de>
   6  *
   7  * This program is free software; you can redistribute it and/or modify
   8  * it under the terms of the GNU General Public License as published by
   9  * the Free Software Foundation; either version 2 of the License, or
  10  * (at your option) any later version.
  11  *
  12  * This program is distributed in the hope that it will be useful,
  13  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15  * GNU General Public License for more details.
  16  *
  17  * You should have received a copy of the GNU General Public License
  18  * along with this program; if not, write to the Free Software
  19  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  20  */
  21 #include <common.h>
  22 #include <watchdog.h>
  23 #include <serial.h>
  24 #include <linux/compiler.h>
  25
  26 #include <asm/io.h>
  27 #include <asm/arch/clk.h>
  28 #include <asm/arch/hardware.h>
  29
  30 #include "atmel_usart.h"
  31
  32 DECLARE_GLOBAL_DATA_PTR;
  33
  34 static void atmel_serial_setbrg(void)
  35 {
  36         atmel_usart3_t *usart = (atmel_usart3_t *)CONFIG_USART_BASE;
  37         unsigned long divisor;
  38         unsigned long usart_hz;
  39
  40         /*
  41          *              Master Clock
  42          * Baud Rate = --------------
  43          *                16 * CD
  44          */
  45         usart_hz = get_usart_clk_rate(CONFIG_USART_ID);
  46         divisor = (usart_hz / 16 + gd->baudrate / 2) / gd->baudrate;
  47         writel(USART3_BF(CD, divisor), &usart->brgr);
  48 }
  49
  50 static int atmel_serial_init(void)
  51 {
  52         atmel_usart3_t *usart = (atmel_usart3_t *)CONFIG_USART_BASE;
  53
  54         /*
  55          * Just in case: drain transmitter register
  56          * 1000us is enough for baudrate >= 9600
  57          */
  58         if (!(readl(&usart->csr) & USART3_BIT(TXEMPTY)))
  59                 __udelay(1000);
  60
  61         writel(USART3_BIT(RSTRX) | USART3_BIT(RSTTX), &usart->cr);
  62
  63         serial_setbrg();
  64
  65         writel((USART3_BF(USART_MODE, USART3_USART_MODE_NORMAL)
  66                            | USART3_BF(USCLKS, USART3_USCLKS_MCK)
  67                            | USART3_BF(CHRL, USART3_CHRL_8)
  68                            | USART3_BF(PAR, USART3_PAR_NONE)
  69                            | USART3_BF(NBSTOP, USART3_NBSTOP_1)),
  70                            &usart->mr);
  71         writel(USART3_BIT(RXEN) | USART3_BIT(TXEN), &usart->cr);
  72         /* 100us is enough for the new settings to be settled */
  73         __udelay(100);
  74
  75         return 0;
  76 }
  77
  78 static void atmel_serial_putc(char c)
  79 {
  80         atmel_usart3_t *usart = (atmel_usart3_t *)CONFIG_USART_BASE;
  81
  82         if (c == '\n')
  83                 serial_putc('\r');
  84
  85         while (!(readl(&usart->csr) & USART3_BIT(TXRDY)));
  86         writel(c, &usart->thr);
  87 }
  88
  89 static int atmel_serial_getc(void)
  90 {
  91         atmel_usart3_t *usart = (atmel_usart3_t *)CONFIG_USART_BASE;
  92
  93         while (!(readl(&usart->csr) & USART3_BIT(RXRDY)))
  94                  WATCHDOG_RESET();
  95         return readl(&usart->rhr);
  96 }
  97
  98 static int atmel_serial_tstc(void)
  99 {
 100         atmel_usart3_t *usart = (atmel_usart3_t *)CONFIG_USART_BASE;
 101         return (readl(&usart->csr) & USART3_BIT(RXRDY)) != 0;
 102 }
 103
 104 static struct serial_device atmel_serial_drv = {
 105         .name   = "atmel_serial",
 106         .start  = atmel_serial_init,
 107         .stop   = NULL,
 108         .setbrg = atmel_serial_setbrg,
 109         .putc   = atmel_serial_putc,
 110         .puts   = default_serial_puts,
 111         .getc   = atmel_serial_getc,
 112         .tstc   = atmel_serial_tstc,
 113 };
 114
 115 void atmel_serial_initialize(void)
 116 {
 117         serial_register(&atmel_serial_drv);
 118 }
 119
 120 __weak struct serial_device *default_serial_console(void)
 121 {
 122         return &atmel_serial_drv;
 123 }