drivers/serial/altera_uart.c

   1 /*
   2  * (C) Copyright 2004, Psyent Corporation <www.psyent.com>
   3  * Scott McNutt <smcnutt@psyent.com>
   4  *
   5  * SPDX-License-Identifier:     GPL-2.0+
   6  */
   7
   8 #include <common.h>
   9 #include <dm.h>
  10 #include <errno.h>
  11 #include <asm/io.h>
  12 #include <linux/compiler.h>
  13 #include <serial.h>
  14
  15 struct altera_uart_regs {
  16         u32     rxdata;         /* Rx data reg */
  17         u32     txdata;         /* Tx data reg */
  18         u32     status;         /* Status reg */
  19         u32     control;        /* Control reg */
  20         u32     divisor;        /* Baud rate divisor reg */
  21         u32     endofpacket;    /* End-of-packet reg */
  22 };
  23
  24 struct altera_uart_platdata {
  25         struct altera_uart_regs *regs;
  26         unsigned int uartclk;
  27 };
  28
  29 /* status register */
  30 #define ALTERA_UART_TMT         (1 << 5)        /* tx empty */
  31 #define ALTERA_UART_TRDY        (1 << 6)        /* tx ready */
  32 #define ALTERA_UART_RRDY        (1 << 7)        /* rx ready */
  33
  34 DECLARE_GLOBAL_DATA_PTR;
  35
  36 static int altera_uart_setbrg(struct udevice *dev, int baudrate)
  37 {
  38         struct altera_uart_platdata *plat = dev->platdata;
  39         struct altera_uart_regs *const regs = plat->regs;
  40         u32 div;
  41
  42         div = (plat->uartclk / baudrate) - 1;
  43         writel(div, &regs->divisor);
  44
  45         return 0;
  46 }
  47
  48 static int altera_uart_putc(struct udevice *dev, const char ch)
  49 {
  50         struct altera_uart_platdata *plat = dev->platdata;
  51         struct altera_uart_regs *const regs = plat->regs;
  52
  53         if (!(readl(&regs->status) & ALTERA_UART_TRDY))
  54                 return -EAGAIN;
  55
  56         writel(ch, &regs->txdata);
  57
  58         return 0;
  59 }
  60
  61 static int altera_uart_pending(struct udevice *dev, bool input)
  62 {
  63         struct altera_uart_platdata *plat = dev->platdata;
  64         struct altera_uart_regs *const regs = plat->regs;
  65         u32 st = readl(&regs->status);
  66
  67         if (input)
  68                 return st & ALTERA_UART_RRDY ? 1 : 0;
  69         else
  70                 return !(st & ALTERA_UART_TMT);
  71 }
  72
  73 static int altera_uart_getc(struct udevice *dev)
  74 {
  75         struct altera_uart_platdata *plat = dev->platdata;
  76         struct altera_uart_regs *const regs = plat->regs;
  77
  78         if (!(readl(&regs->status) & ALTERA_UART_RRDY))
  79                 return -EAGAIN;
  80
  81         return readl(&regs->rxdata) & 0xff;
  82 }
  83
  84 static int altera_uart_probe(struct udevice *dev)
  85 {
  86         return 0;
  87 }
  88
  89 static int altera_uart_ofdata_to_platdata(struct udevice *dev)
  90 {
  91         struct altera_uart_platdata *plat = dev_get_platdata(dev);
  92
  93         plat->regs = ioremap(dev_get_addr(dev),
  94                 sizeof(struct altera_uart_regs));
  95         plat->uartclk = fdtdec_get_int(gd->fdt_blob, dev->of_offset,
  96                 "clock-frequency", 0);
  97
  98         return 0;
  99 }
 100
 101 static const struct dm_serial_ops altera_uart_ops = {
 102         .putc = altera_uart_putc,
 103         .pending = altera_uart_pending,
 104         .getc = altera_uart_getc,
 105         .setbrg = altera_uart_setbrg,
 106 };
 107
 108 static const struct udevice_id altera_uart_ids[] = {
 109         { .compatible = "altr,uart-1.0", },
 110         { }
 111 };
 112
 113 U_BOOT_DRIVER(altera_uart) = {
 114         .name   = "altera_uart",
 115         .id     = UCLASS_SERIAL,
 116         .of_match = altera_uart_ids,
 117         .ofdata_to_platdata = altera_uart_ofdata_to_platdata,
 118         .platdata_auto_alloc_size = sizeof(struct altera_uart_platdata),
 119         .probe = altera_uart_probe,
 120         .ops    = &altera_uart_ops,
 121         .flags = DM_FLAG_PRE_RELOC,
 122 };
 123
 124 #ifdef CONFIG_DEBUG_UART_ALTERA_UART
 125
 126 #include <debug_uart.h>
 127
 128 void debug_uart_init(void)
 129 {
 130         struct altera_uart_regs *regs = (void *)CONFIG_DEBUG_UART_BASE;
 131         u32 div;
 132
 133         div = (CONFIG_DEBUG_UART_CLOCK / CONFIG_BAUDRATE) - 1;
 134         writel(div, &regs->divisor);
 135 }
 136
 137 static inline void _debug_uart_putc(int ch)
 138 {
 139         struct altera_uart_regs *regs = (void *)CONFIG_DEBUG_UART_BASE;
 140
 141         while (1) {
 142                 u32 st = readl(&regs->status);
 143
 144                 if (st & ALTERA_UART_TRDY)
 145                         break;
 146         }
 147
 148         writel(ch, &regs->txdata);
 149 }
 150
 151 DEBUG_UART_FUNCS
 152
 153 #endif