arch/ppc/boot/simple/mpc52xx_tty.c

   1 /*
   2  * arch/ppc/boot/simple/mpc52xx_tty.c
   3  *
   4  * Minimal serial functions needed to send messages out a MPC52xx
   5  * Programmable Serial Controller (PSC).
   6  *
   7  * Author: Dale Farnsworth <dfarnsworth@mvista.com>
   8  *
   9  * 2003-2004 (c) MontaVista, Software, Inc.  This file is licensed under the
  10  * terms of the GNU General Public License version 2.  This program is licensed
  11  * "as is" without any warranty of any kind, whether express or implied.
  12  */
  13
  14 #include <linux/config.h>
  15 #include <linux/types.h>
  16 #include <asm/uaccess.h>
  17 #include <asm/mpc52xx.h>
  18 #include <asm/mpc52xx_psc.h>
  19 #include <asm/serial.h>
  20 #include <asm/io.h>
  21 #include <asm/time.h>
  22
  23
  24 #ifdef MPC52xx_PF_CONSOLE_PORT
  25 #define MPC52xx_CONSOLE MPC52xx_PSCx_OFFSET(MPC52xx_PF_CONSOLE_PORT)
  26 #define MPC52xx_PSC_CONFIG_SHIFT ((MPC52xx_PF_CONSOLE_PORT-1)<<2)
  27 #else
  28 #error "MPC52xx_PF_CONSOLE_PORT not defined"
  29 #endif
  30
  31 static struct mpc52xx_psc __iomem *psc =
  32         (struct mpc52xx_psc __iomem *) MPC52xx_PA(MPC52xx_CONSOLE);
  33
  34 /* The decrementer counts at the system bus clock frequency
  35  * divided by four.  The most accurate time base is connected to the
  36  * rtc.  We read the decrementer change during one rtc tick
  37  * and multiply by 4 to get the system bus clock frequency. Since a
  38  * rtc tick is one seconds, and that's pretty long, we change the rtc
  39  * dividers temporarly to set them 64x faster ;)
  40  */
  41 static int
  42 mpc52xx_ipbfreq(void)
  43 {
  44         struct mpc52xx_rtc __iomem *rtc =
  45                 (struct mpc52xx_rtc __iomem *) MPC52xx_PA(MPC52xx_RTC_OFFSET);
  46         struct mpc52xx_cdm __iomem *cdm =
  47                 (struct mpc52xx_cdm __iomem *) MPC52xx_PA(MPC52xx_CDM_OFFSET);
  48         int current_time, previous_time;
  49         int tbl_start, tbl_end;
  50         int xlbfreq, ipbfreq;
  51
  52         out_be32(&rtc->dividers, 0x8f1f0000);   /* Set RTC 64x faster */
  53         previous_time = in_be32(&rtc->time);
  54         while ((current_time = in_be32(&rtc->time)) == previous_time) ;
  55         tbl_start = get_tbl();
  56         previous_time = current_time;
  57         while ((current_time = in_be32(&rtc->time)) == previous_time) ;
  58         tbl_end = get_tbl();
  59         out_be32(&rtc->dividers, 0xffff0000);   /* Restore RTC */
  60
  61         xlbfreq = (tbl_end - tbl_start) << 8;
  62         ipbfreq = (in_8(&cdm->ipb_clk_sel) & 1) ? xlbfreq / 2 : xlbfreq;
  63
  64         return ipbfreq;
  65 }
  66
  67 unsigned long
  68 serial_init(int ignored, void *ignored2)
  69 {
  70         struct mpc52xx_gpio __iomem *gpio =
  71                 (struct mpc52xx_gpio __iomem *) MPC52xx_PA(MPC52xx_GPIO_OFFSET);
  72         int divisor;
  73         int mode1;
  74         int mode2;
  75         u32 val32;
  76
  77         static int been_here = 0;
  78
  79         if (been_here)
  80                 return 0;
  81
  82         been_here = 1;
  83
  84         val32 = in_be32(&gpio->port_config);
  85         val32 &= ~(0x7 << MPC52xx_PSC_CONFIG_SHIFT);
  86         val32 |= MPC52xx_GPIO_PSC_CONFIG_UART_WITHOUT_CD
  87                                 << MPC52xx_PSC_CONFIG_SHIFT;
  88         out_be32(&gpio->port_config, val32);
  89
  90         out_8(&psc->command, MPC52xx_PSC_RST_TX
  91                         | MPC52xx_PSC_RX_DISABLE | MPC52xx_PSC_TX_ENABLE);
  92         out_8(&psc->command, MPC52xx_PSC_RST_RX);
  93
  94         out_be32(&psc->sicr, 0x0);
  95         out_be16(&psc->mpc52xx_psc_clock_select, 0xdd00);
  96         out_be16(&psc->tfalarm, 0xf8);
  97
  98         out_8(&psc->command, MPC52xx_PSC_SEL_MODE_REG_1
  99                         | MPC52xx_PSC_RX_ENABLE
 100                         | MPC52xx_PSC_TX_ENABLE);
 101
 102         divisor = ((mpc52xx_ipbfreq()
 103                         / (CONFIG_SERIAL_MPC52xx_CONSOLE_BAUD * 16)) + 1) >> 1;
 104
 105         mode1 = MPC52xx_PSC_MODE_8_BITS | MPC52xx_PSC_MODE_PARNONE
 106                         | MPC52xx_PSC_MODE_ERR;
 107         mode2 = MPC52xx_PSC_MODE_ONE_STOP;
 108
 109         out_8(&psc->ctur, divisor>>8);
 110         out_8(&psc->ctlr, divisor);
 111         out_8(&psc->command, MPC52xx_PSC_SEL_MODE_REG_1);
 112         out_8(&psc->mode, mode1);
 113         out_8(&psc->mode, mode2);
 114
 115         return 0;       /* ignored */
 116 }
 117
 118 void
 119 serial_putc(void *ignored, const char c)
 120 {
 121         serial_init(0, NULL);
 122
 123         while (!(in_be16(&psc->mpc52xx_psc_status) & MPC52xx_PSC_SR_TXEMP)) ;
 124         out_8(&psc->mpc52xx_psc_buffer_8, c);
 125         while (!(in_be16(&psc->mpc52xx_psc_status) & MPC52xx_PSC_SR_TXEMP)) ;
 126 }
 127
 128 char
 129 serial_getc(void *ignored)
 130 {
 131         while (!(in_be16(&psc->mpc52xx_psc_status) & MPC52xx_PSC_SR_RXRDY)) ;
 132
 133         return in_8(&psc->mpc52xx_psc_buffer_8);
 134 }
 135
 136 int
 137 serial_tstc(void *ignored)
 138 {
 139         return (in_be16(&psc->mpc52xx_psc_status) & MPC52xx_PSC_SR_RXRDY) != 0;
 140 }