drivers/serial/serial_lpuart.c

   1 /*
   2  * Copyright 2013 Freescale Semiconductor, Inc.
   3  *
   4  * SPDX-License-Identifier:     GPL-2.0+
   5  */
   6
   7 #include <common.h>
   8 #include <watchdog.h>
   9 #include <asm/io.h>
  10 #include <serial.h>
  11 #include <linux/compiler.h>
  12 #include <asm/arch/imx-regs.h>
  13 #include <asm/arch/clock.h>
  14
  15 #define US1_TDRE        (1 << 7)
  16 #define US1_RDRF        (1 << 5)
  17 #define US1_OR          (1 << 3)
  18 #define UC2_TE          (1 << 3)
  19 #define UC2_RE          (1 << 2)
  20
  21 DECLARE_GLOBAL_DATA_PTR;
  22
  23 struct lpuart_fsl *base = (struct lpuart_fsl *)LPUART_BASE;
  24
  25 static void lpuart_serial_setbrg(void)
  26 {
  27         u32 clk = mxc_get_clock(MXC_UART_CLK);
  28         u16 sbr;
  29
  30         if (!gd->baudrate)
  31                 gd->baudrate = CONFIG_BAUDRATE;
  32
  33         sbr = (u16)(clk / (16 * gd->baudrate));
  34         /* place adjustment later - n/32 BRFA */
  35
  36         __raw_writeb(sbr >> 8, &base->ubdh);
  37         __raw_writeb(sbr & 0xff, &base->ubdl);
  38 }
  39
  40 static int lpuart_serial_getc(void)
  41 {
  42         while (!(__raw_readb(&base->us1) & (US1_RDRF | US1_OR)))
  43                 WATCHDOG_RESET();
  44
  45         barrier();
  46
  47         return __raw_readb(&base->ud);
  48 }
  49
  50 static void lpuart_serial_putc(const char c)
  51 {
  52         if (c == '\n')
  53                 serial_putc('\r');
  54
  55         while (!(__raw_readb(&base->us1) & US1_TDRE))
  56                 WATCHDOG_RESET();
  57
  58         __raw_writeb(c, &base->ud);
  59 }
  60
  61 /*
  62  * Test whether a character is in the RX buffer
  63  */
  64 static int lpuart_serial_tstc(void)
  65 {
  66         if (__raw_readb(&base->urcfifo) == 0)
  67                 return 0;
  68
  69         return 1;
  70 }
  71
  72 /*
  73  * Initialise the serial port with the given baudrate. The settings
  74  * are always 8 data bits, no parity, 1 stop bit, no start bits.
  75  */
  76 static int lpuart_serial_init(void)
  77 {
  78         u8 ctrl;
  79
  80         ctrl = __raw_readb(&base->uc2);
  81         ctrl &= ~UC2_RE;
  82         ctrl &= ~UC2_TE;
  83         __raw_writeb(ctrl, &base->uc2);
  84
  85         __raw_writeb(0, &base->umodem);
  86         __raw_writeb(0, &base->uc1);
  87
  88         /* provide data bits, parity, stop bit, etc */
  89
  90         serial_setbrg();
  91
  92         __raw_writeb(UC2_RE | UC2_TE, &base->uc2);
  93
  94         return 0;
  95 }
  96
  97 static struct serial_device lpuart_serial_drv = {
  98         .name = "lpuart_serial",
  99         .start = lpuart_serial_init,
 100         .stop = NULL,
 101         .setbrg = lpuart_serial_setbrg,
 102         .putc = lpuart_serial_putc,
 103         .puts = default_serial_puts,
 104         .getc = lpuart_serial_getc,
 105         .tstc = lpuart_serial_tstc,
 106 };
 107
 108 void lpuart_serial_initialize(void)
 109 {
 110         serial_register(&lpuart_serial_drv);
 111 }
 112
 113 __weak struct serial_device *default_serial_console(void)
 114 {
 115         return &lpuart_serial_drv;
 116 }