text: // SPDX-License-Identifier: GPL-2.0+
  /*
   * (C) Copyright 2004, Psyent Corporation <www.psyent.com>
   * Scott McNutt <smcnutt@psyent.com>
   */
  
  #include <common.h>
  #include <dm.h>
  #include <errno.h>
  #include <serial.h>
  #include <asm/io.h>
  
  DECLARE_GLOBAL_DATA_PTR;
  
  /* status register */
  #define ALTERA_UART_TMT		BIT(5)	/* tx empty */
  #define ALTERA_UART_TRDY	BIT(6)	/* tx ready */
  #define ALTERA_UART_RRDY	BIT(7)	/* rx ready */
  
  struct altera_uart_regs {
  	u32	rxdata;		/* Rx data reg */
  	u32	txdata;		/* Tx data reg */
  	u32	status;		/* Status reg */
  	u32	control;	/* Control reg */
  	u32	divisor;	/* Baud rate divisor reg */
  	u32	endofpacket;	/* End-of-packet reg */
  };
  
  struct altera_uart_platdata {
  	struct altera_uart_regs *regs;
  	unsigned int uartclk;
  };
  
  static int altera_uart_setbrg(struct udevice *dev, int baudrate)
  {
  	struct altera_uart_platdata *plat = dev->platdata;
  	struct altera_uart_regs *const regs = plat->regs;
  	u32 div;
  
  	div = (plat->uartclk / baudrate) - 1;
  	writel(div, &regs->divisor);
  
  	return 0;
  }
  
  static int altera_uart_putc(struct udevice *dev, const char ch)
  {
  	struct altera_uart_platdata *plat = dev->platdata;
  	struct altera_uart_regs *const regs = plat->regs;
  
  	if (!(readl(&regs->status) & ALTERA_UART_TRDY))
  		return -EAGAIN;
  
  	writel(ch, &regs->txdata);
  
  	return 0;
  }
  
  static int altera_uart_pending(struct udevice *dev, bool input)
  {
  	struct altera_uart_platdata *plat = dev->platdata;
  	struct altera_uart_regs *const regs = plat->regs;
  	u32 st = readl(&regs->status);
  
  	if (input)
  		return st & ALTERA_UART_RRDY ? 1 : 0;
  	else
  		return !(st & ALTERA_UART_TMT);
  }
  
  static int altera_uart_getc(struct udevice *dev)
  {
  	struct altera_uart_platdata *plat = dev->platdata;
  	struct altera_uart_regs *const regs = plat->regs;
  
  	if (!(readl(&regs->status) & ALTERA_UART_RRDY))
  		return -EAGAIN;
  
  	return readl(&regs->rxdata) & 0xff;
  }
  
  static int altera_uart_probe(struct udevice *dev)
  {
  	return 0;
  }
  
  static int altera_uart_ofdata_to_platdata(struct udevice *dev)
  {
  	struct altera_uart_platdata *plat = dev_get_platdata(dev);
  
  	plat->regs = map_physmem(devfdt_get_addr(dev),
  				 sizeof(struct altera_uart_regs),
  				 MAP_NOCACHE);
  	plat->uartclk = fdtdec_get_int(gd->fdt_blob, dev_of_offset(dev),
  		"clock-frequency", 0);
  
  	return 0;
  }
  
  static const struct dm_serial_ops altera_uart_ops = {
  	.putc = altera_uart_putc,
  	.pending = altera_uart_pending,
  	.getc = altera_uart_getc,
  	.setbrg = altera_uart_setbrg,
  };
  
  static const struct udevice_id altera_uart_ids[] = {
  	{ .compatible = "altr,uart-1.0" },
  	{}
  };
  
  U_BOOT_DRIVER(altera_uart) = {
  	.name	= "altera_uart",
  	.id	= UCLASS_SERIAL,
  	.of_match = altera_uart_ids,
  	.ofdata_to_platdata = altera_uart_ofdata_to_platdata,
  	.platdata_auto_alloc_size = sizeof(struct altera_uart_platdata),
  	.probe = altera_uart_probe,
  	.ops	= &altera_uart_ops,
  	.flags = DM_FLAG_PRE_RELOC,
  };
  
  #ifdef CONFIG_DEBUG_UART_ALTERA_UART
  
  #include <debug_uart.h>
  
  static inline void _debug_uart_init(void)
  {
  	struct altera_uart_regs *regs = (void *)CONFIG_DEBUG_UART_BASE;
  	u32 div;
  
  	div = (CONFIG_DEBUG_UART_CLOCK / CONFIG_BAUDRATE) - 1;
  	writel(div, &regs->divisor);
  }
  
  static inline void _debug_uart_putc(int ch)
  {
  	struct altera_uart_regs *regs = (void *)CONFIG_DEBUG_UART_BASE;
  
  	while (1) {
  		u32 st = readl(&regs->status);
  
  		if (st & ALTERA_UART_TRDY)
  			break;
  	}
  
  	writel(ch, &regs->txdata);
  }
  
  DEBUG_UART_FUNCS
  
  #endif
  