text: /*
   * Copyright (c) 2014 The Chromium OS Authors.
   *
   * SPDX-License-Identifier:	GPL-2.0+
   */
  
  #include <common.h>
  #include <dm.h>
  #include <environment.h>
  #include <errno.h>
  #include <fdtdec.h>
  #include <os.h>
  #include <serial.h>
  #include <stdio_dev.h>
  #include <watchdog.h>
  #include <dm/lists.h>
  #include <dm/device-internal.h>
  
  #include <ns16550.h>
  
  DECLARE_GLOBAL_DATA_PTR;
  
  /*
   * Table with supported baudrates (defined in config_xyz.h)
   */
  static const unsigned long baudrate_table[] = CONFIG_SYS_BAUDRATE_TABLE;
  
  #ifndef CONFIG_SYS_MALLOC_F_LEN
  #error "Serial is required before relocation - define CONFIG_SYS_MALLOC_F_LEN to make this work"
  #endif
  
  static void serial_find_console_or_panic(void)
  {
  	struct udevice *dev;
  
  #ifdef CONFIG_OF_CONTROL
  	int node;
  
  	/* Check for a chosen console */
  	node = fdtdec_get_chosen_node(gd->fdt_blob, "stdout-path");
  	if (node < 0)
  		node = fdt_path_offset(gd->fdt_blob, "console");
  	if (!uclass_get_device_by_of_offset(UCLASS_SERIAL, node, &dev)) {
  		gd->cur_serial_dev = dev;
  		return;
  	}
  
  	/*
  	 * If the console is not marked to be bound before relocation, bind
  	 * it anyway.
  	 */
  	if (node > 0 &&
  	    !lists_bind_fdt(gd->dm_root, gd->fdt_blob, node, &dev)) {
  		if (!device_probe(dev)) {
  			gd->cur_serial_dev = dev;
  			return;
  		}
  	}
  #endif
  	/*
  	 * Try to use CONFIG_CONS_INDEX if available (it is numbered from 1!).
  	 *
  	 * Failing that, get the device with sequence number 0, or in extremis
  	 * just the first serial device we can find. But we insist on having
  	 * a console (even if it is silent).
  	 */
  #ifdef CONFIG_CONS_INDEX
  #define INDEX (CONFIG_CONS_INDEX - 1)
  #else
  #define INDEX 0
  #endif
  	if (uclass_get_device_by_seq(UCLASS_SERIAL, INDEX, &dev) &&
  	    uclass_get_device(UCLASS_SERIAL, INDEX, &dev) &&
  	    (uclass_first_device(UCLASS_SERIAL, &dev) || !dev))
  		panic("No serial driver found");
  #undef INDEX
  	gd->cur_serial_dev = dev;
  }
  
  /* Called prior to relocation */
  int serial_init(void)
  {
  	serial_find_console_or_panic();
  	gd->flags |= GD_FLG_SERIAL_READY;
  
  	return 0;
  }
  
  /* Called after relocation */
  void serial_initialize(void)
  {
  	serial_find_console_or_panic();
  }
  
  static void _serial_putc(struct udevice *dev, char ch)
  {
  	struct dm_serial_ops *ops = serial_get_ops(dev);
  	int err;
  
  	do {
  		err = ops->putc(dev, ch);
  	} while (err == -EAGAIN);
  	if (ch == '\n')
  		_serial_putc(dev, '\r');
  }
  
  static void _serial_puts(struct udevice *dev, const char *str)
  {
  	while (*str)
  		_serial_putc(dev, *str++);
  }
  
  static int _serial_getc(struct udevice *dev)
  {
  	struct dm_serial_ops *ops = serial_get_ops(dev);
  	int err;
  
  	do {
  		err = ops->getc(dev);
  		if (err == -EAGAIN)
  			WATCHDOG_RESET();
  	} while (err == -EAGAIN);
  
  	return err >= 0 ? err : 0;
  }
  
  static int _serial_tstc(struct udevice *dev)
  {
  	struct dm_serial_ops *ops = serial_get_ops(dev);
  
  	if (ops->pending)
  		return ops->pending(dev, true);
  
  	return 1;
  }
  
  void serial_putc(char ch)
  {
  	_serial_putc(gd->cur_serial_dev, ch);
  }
  
  void serial_puts(const char *str)
  {
  	_serial_puts(gd->cur_serial_dev, str);
  }
  
  int serial_getc(void)
  {
  	return _serial_getc(gd->cur_serial_dev);
  }
  
  int serial_tstc(void)
  {
  	return _serial_tstc(gd->cur_serial_dev);
  }
  
  void serial_setbrg(void)
  {
  	struct dm_serial_ops *ops = serial_get_ops(gd->cur_serial_dev);
  
  	if (ops->setbrg)
  		ops->setbrg(gd->cur_serial_dev, gd->baudrate);
  }
  
  void serial_stdio_init(void)
  {
  }
  
  #ifdef CONFIG_DM_STDIO
  static void serial_stub_putc(struct stdio_dev *sdev, const char ch)
  {
  	_serial_putc(sdev->priv, ch);
  }
  #endif
  
  void serial_stub_puts(struct stdio_dev *sdev, const char *str)
  {
  	_serial_puts(sdev->priv, str);
  }
  
  int serial_stub_getc(struct stdio_dev *sdev)
  {
  	return _serial_getc(sdev->priv);
  }
  
  int serial_stub_tstc(struct stdio_dev *sdev)
  {
  	return _serial_tstc(sdev->priv);
  }
  
  /**
   * on_baudrate() - Update the actual baudrate when the env var changes
   *
   * This will check for a valid baudrate and only apply it if valid.
   */
  static int on_baudrate(const char *name, const char *value, enum env_op op,
  	int flags)
  {
  	int i;
  	int baudrate;
  
  	switch (op) {
  	case env_op_create:
  	case env_op_overwrite:
  		/*
  		 * Switch to new baudrate if new baudrate is supported
  		 */
  		baudrate = simple_strtoul(value, NULL, 10);
  
  		/* Not actually changing */
  		if (gd->baudrate == baudrate)
  			return 0;
  
  		for (i = 0; i < ARRAY_SIZE(baudrate_table); ++i) {
  			if (baudrate == baudrate_table[i])
  				break;
  		}
  		if (i == ARRAY_SIZE(baudrate_table)) {
  			if ((flags & H_FORCE) == 0)
  				printf("## Baudrate %d bps not supported\n",
  				       baudrate);
  			return 1;
  		}
  		if ((flags & H_INTERACTIVE) != 0) {
  			printf("## Switch baudrate to %d bps and press ENTER ...\n",
  			       baudrate);
  			udelay(50000);
  		}
  
  		gd->baudrate = baudrate;
  
  		serial_setbrg();
  
  		udelay(50000);
  
  		if ((flags & H_INTERACTIVE) != 0)
  			while (1) {
  				if (getc() == '\r')
  					break;
  			}
  
  		return 0;
  	case env_op_delete:
  		printf("## Baudrate may not be deleted\n");
  		return 1;
  	default:
  		return 0;
  	}
  }
  U_BOOT_ENV_CALLBACK(baudrate, on_baudrate);
  
  static int serial_post_probe(struct udevice *dev)
  {
  	struct dm_serial_ops *ops = serial_get_ops(dev);
  #ifdef CONFIG_DM_STDIO
  	struct serial_dev_priv *upriv = dev->uclass_priv;
  	struct stdio_dev sdev;
  #endif
  	int ret;
  
  	/* Set the baud rate */
  	if (ops->setbrg) {
  		ret = ops->setbrg(dev, gd->baudrate);
  		if (ret)
  			return ret;
  	}
  
  #ifdef CONFIG_DM_STDIO
  	if (!(gd->flags & GD_FLG_RELOC))
  		return 0;
  	memset(&sdev, '\0', sizeof(sdev));
  
  	strncpy(sdev.name, dev->name, sizeof(sdev.name));
  	sdev.flags = DEV_FLAGS_OUTPUT | DEV_FLAGS_INPUT;
  	sdev.priv = dev;
  	sdev.putc = serial_stub_putc;
  	sdev.puts = serial_stub_puts;
  	sdev.getc = serial_stub_getc;
  	sdev.tstc = serial_stub_tstc;
  	stdio_register_dev(&sdev, &upriv->sdev);
  #endif
  	return 0;
  }
  
  static int serial_pre_remove(struct udevice *dev)
  {
  #ifdef CONFIG_SYS_STDIO_DEREGISTER
  	struct serial_dev_priv *upriv = dev->uclass_priv;
  
  	if (stdio_deregister_dev(upriv->sdev, 0))
  		return -EPERM;
  #endif
  
  	return 0;
  }
  
  UCLASS_DRIVER(serial) = {
  	.id		= UCLASS_SERIAL,
  	.name		= "serial",
  	.post_probe	= serial_post_probe,
  	.pre_remove	= serial_pre_remove,
  	.per_device_auto_alloc_size = sizeof(struct serial_dev_priv),
  };
  