arch/ppc/boot/simple/mpc52xx_tty.c

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