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 UC2_TE          (1 << 3)
  18 #define UC2_RE          (1 << 2)
  19
  20 DECLARE_GLOBAL_DATA_PTR;
  21
  22 struct lpuart_fsl *base = (struct lpuart_fsl *)LPUART_BASE;
  23
  24 static void lpuart_serial_setbrg(void)
  25 {
  26         u32 clk = mxc_get_clock(MXC_UART_CLK);
  27         u16 sbr;
  28
  29         if (!gd->baudrate)
  30                 gd->baudrate = CONFIG_BAUDRATE;
  31
  32         sbr = (u16)(clk / (16 * gd->baudrate));
  33         /* place adjustment later - n/32 BRFA */
  34
  35         __raw_writeb(sbr >> 8, &base->ubdh);
  36         __raw_writeb(sbr & 0xff, &base->ubdl);
  37 }
  38
  39 static int lpuart_serial_getc(void)
  40 {
  41         u8 status;
  42
  43         while (!(__raw_readb(&base->us1) & US1_RDRF))
  44                 WATCHDOG_RESET();
  45
  46         status = __raw_readb(&base->us1);
  47         status |= US1_RDRF;
  48         __raw_writeb(status, &base->us1);
  49
  50         return __raw_readb(&base->ud);
  51 }
  52
  53 static void lpuart_serial_putc(const char c)
  54 {
  55         if (c == '\n')
  56                 serial_putc('\r');
  57
  58         while (!(__raw_readb(&base->us1) & US1_TDRE))
  59                 WATCHDOG_RESET();
  60
  61         __raw_writeb(c, &base->ud);
  62 }
  63
  64 /*
  65  * Test whether a character is in the RX buffer
  66  */
  67 static int lpuart_serial_tstc(void)
  68 {
  69         if (__raw_readb(&base->urcfifo) == 0)
  70                 return 0;
  71
  72         return 1;
  73 }
  74
  75 /*
  76  * Initialise the serial port with the given baudrate. The settings
  77  * are always 8 data bits, no parity, 1 stop bit, no start bits.
  78  */
  79 static int lpuart_serial_init(void)
  80 {
  81         u8 ctrl;
  82
  83         ctrl = __raw_readb(&base->uc2);
  84         ctrl &= ~UC2_RE;
  85         ctrl &= ~UC2_TE;
  86         __raw_writeb(ctrl, &base->uc2);
  87
  88         __raw_writeb(0, &base->umodem);
  89         __raw_writeb(0, &base->uc1);
  90
  91         /* provide data bits, parity, stop bit, etc */
  92
  93         serial_setbrg();
  94
  95         __raw_writeb(UC2_RE | UC2_TE, &base->uc2);
  96
  97         return 0;
  98 }
  99
 100 static struct serial_device lpuart_serial_drv = {
 101         .name = "lpuart_serial",
 102         .start = lpuart_serial_init,
 103         .stop = NULL,
 104         .setbrg = lpuart_serial_setbrg,
 105         .putc = lpuart_serial_putc,
 106         .puts = default_serial_puts,
 107         .getc = lpuart_serial_getc,
 108         .tstc = lpuart_serial_tstc,
 109 };
 110
 111 void lpuart_serial_initialize(void)
 112 {
 113         serial_register(&lpuart_serial_drv);
 114 }
 115
 116 __weak struct serial_device *default_serial_console(void)
 117 {
 118         return &lpuart_serial_drv;
 119 }