drivers/serial/lpc32xx_hsuart.c

   1 /*
   2  * Copyright (C) 2011 Vladimir Zapolskiy <vz@mleia.com>
   3  *
   4  * SPDX-License-Identifier:     GPL-2.0+
   5  */
   6
   7 #include <common.h>
   8 #include <asm/arch/cpu.h>
   9 #include <asm/arch/clk.h>
  10 #include <asm/arch/uart.h>
  11 #include <asm/io.h>
  12 #include <serial.h>
  13 #include <linux/compiler.h>
  14
  15 DECLARE_GLOBAL_DATA_PTR;
  16
  17 static struct hsuart_regs *hsuart = (struct hsuart_regs *)HS_UART_BASE;
  18
  19 static void lpc32xx_serial_setbrg(void)
  20 {
  21         u32 div;
  22
  23         /* UART rate = PERIPH_CLK / ((HSU_RATE + 1) x 14) */
  24         div = (get_serial_clock() / 14 + gd->baudrate / 2) / gd->baudrate - 1;
  25         if (div > 255)
  26                 div = 255;
  27
  28         writel(div, &hsuart->rate);
  29 }
  30
  31 static int lpc32xx_serial_getc(void)
  32 {
  33         while (!(readl(&hsuart->level) & HSUART_LEVEL_RX))
  34                 /* NOP */;
  35
  36         return readl(&hsuart->rx) & HSUART_RX_DATA;
  37 }
  38
  39 static void lpc32xx_serial_putc(const char c)
  40 {
  41         writel(c, &hsuart->tx);
  42
  43         /* Wait for character to be sent */
  44         while (readl(&hsuart->level) & HSUART_LEVEL_TX)
  45                 /* NOP */;
  46 }
  47
  48 static int lpc32xx_serial_tstc(void)
  49 {
  50         if (readl(&hsuart->level) & HSUART_LEVEL_RX)
  51                 return 1;
  52
  53         return 0;
  54 }
  55
  56 static int lpc32xx_serial_init(void)
  57 {
  58         lpc32xx_serial_setbrg();
  59
  60         /* Disable hardware RTS and CTS flow control, set up RX and TX FIFO */
  61         writel(HSUART_CTRL_TMO_16 | HSUART_CTRL_HSU_OFFSET(20) |
  62                HSUART_CTRL_HSU_RX_TRIG_32 | HSUART_CTRL_HSU_TX_TRIG_0,
  63                &hsuart->ctrl);
  64         return 0;
  65 }
  66
  67 static struct serial_device lpc32xx_serial_drv = {
  68         .name   = "lpc32xx_serial",
  69         .start  = lpc32xx_serial_init,
  70         .stop   = NULL,
  71         .setbrg = lpc32xx_serial_setbrg,
  72         .putc   = lpc32xx_serial_putc,
  73         .puts   = default_serial_puts,
  74         .getc   = lpc32xx_serial_getc,
  75         .tstc   = lpc32xx_serial_tstc,
  76 };
  77
  78 void lpc32xx_serial_initialize(void)
  79 {
  80         serial_register(&lpc32xx_serial_drv);
  81 }
  82
  83 __weak struct serial_device *default_serial_console(void)
  84 {
  85         return &lpc32xx_serial_drv;
  86 }