text: /*
   * Renesas Emma Mobile 8250 driver
   *
   *  Copyright (C) 2012 Magnus Damm
   *
   * This program is free software; you can redistribute it and/or modify
   * it under the terms of the GNU General Public License as published by
   * the Free Software Foundation; either version 2 of the License
   *
   * This program is distributed in the hope that it will be useful,
   * but WITHOUT ANY WARRANTY; without even the implied warranty of
   * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   * GNU General Public License for more details.
   *
   * You should have received a copy of the GNU General Public License
   * along with this program; if not, write to the Free Software
   * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
   */
  
  #include <linux/device.h>
  #include <linux/init.h>
  #include <linux/io.h>
  #include <linux/module.h>
  #include <linux/serial_8250.h>
  #include <linux/serial_core.h>
  #include <linux/serial_reg.h>
  #include <linux/platform_device.h>
  #include <linux/clk.h>
  #include <linux/slab.h>
  
  #include "8250.h"
  
  #define UART_DLL_EM 9
  #define UART_DLM_EM 10
  
  struct serial8250_em_priv {
  	struct clk *sclk;
  	int line;
  };
  
  static void serial8250_em_serial_out(struct uart_port *p, int offset, int value)
  {
  	switch (offset) {
  	case UART_TX: /* TX @ 0x00 */
  		writeb(value, p->membase);
  		break;
  	case UART_FCR: /* FCR @ 0x0c (+1) */
  	case UART_LCR: /* LCR @ 0x10 (+1) */
  	case UART_MCR: /* MCR @ 0x14 (+1) */
  	case UART_SCR: /* SCR @ 0x20 (+1) */
  		writel(value, p->membase + ((offset + 1) << 2));
  		break;
  	case UART_IER: /* IER @ 0x04 */
  		value &= 0x0f; /* only 4 valid bits - not Xscale */
  		/* fall-through */
  	case UART_DLL_EM: /* DLL @ 0x24 (+9) */
  	case UART_DLM_EM: /* DLM @ 0x28 (+9) */
  		writel(value, p->membase + (offset << 2));
  	}
  }
  
  static unsigned int serial8250_em_serial_in(struct uart_port *p, int offset)
  {
  	switch (offset) {
  	case UART_RX: /* RX @ 0x00 */
  		return readb(p->membase);
  	case UART_MCR: /* MCR @ 0x14 (+1) */
  	case UART_LSR: /* LSR @ 0x18 (+1) */
  	case UART_MSR: /* MSR @ 0x1c (+1) */
  	case UART_SCR: /* SCR @ 0x20 (+1) */
  		return readl(p->membase + ((offset + 1) << 2));
  	case UART_IER: /* IER @ 0x04 */
  	case UART_IIR: /* IIR @ 0x08 */
  	case UART_DLL_EM: /* DLL @ 0x24 (+9) */
  	case UART_DLM_EM: /* DLM @ 0x28 (+9) */
  		return readl(p->membase + (offset << 2));
  	}
  	return 0;
  }
  
  static int serial8250_em_serial_dl_read(struct uart_8250_port *up)
  {
  	return serial_in(up, UART_DLL_EM) | serial_in(up, UART_DLM_EM) << 8;
  }
  
  static void serial8250_em_serial_dl_write(struct uart_8250_port *up, int value)
  {
  	serial_out(up, UART_DLL_EM, value & 0xff);
  	serial_out(up, UART_DLM_EM, value >> 8 & 0xff);
  }
  
  static int serial8250_em_probe(struct platform_device *pdev)
  {
  	struct resource *regs = platform_get_resource(pdev, IORESOURCE_MEM, 0);
  	struct resource *irq = platform_get_resource(pdev, IORESOURCE_IRQ, 0);
  	struct serial8250_em_priv *priv;
  	struct uart_8250_port up;
  	int ret;
  
  	if (!regs || !irq) {
  		dev_err(&pdev->dev, "missing registers or irq\n");
  		return -EINVAL;
  	}
  
  	priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL);
  	if (!priv) {
  		dev_err(&pdev->dev, "unable to allocate private data\n");
  		return -ENOMEM;
  	}
  
  	priv->sclk = devm_clk_get(&pdev->dev, "sclk");
  	if (IS_ERR(priv->sclk)) {
  		dev_err(&pdev->dev, "unable to get clock\n");
  		return PTR_ERR(priv->sclk);
  	}
  
  	memset(&up, 0, sizeof(up));
  	up.port.mapbase = regs->start;
  	up.port.irq = irq->start;
  	up.port.type = PORT_UNKNOWN;
  	up.port.flags = UPF_BOOT_AUTOCONF | UPF_FIXED_PORT | UPF_IOREMAP;
  	up.port.dev = &pdev->dev;
  	up.port.private_data = priv;
  
  	clk_prepare_enable(priv->sclk);
  	up.port.uartclk = clk_get_rate(priv->sclk);
  
  	up.port.iotype = UPIO_MEM32;
  	up.port.serial_in = serial8250_em_serial_in;
  	up.port.serial_out = serial8250_em_serial_out;
  	up.dl_read = serial8250_em_serial_dl_read;
  	up.dl_write = serial8250_em_serial_dl_write;
  
  	ret = serial8250_register_8250_port(&up);
  	if (ret < 0) {
  		dev_err(&pdev->dev, "unable to register 8250 port\n");
  		clk_disable_unprepare(priv->sclk);
  		return ret;
  	}
  
  	priv->line = ret;
  	platform_set_drvdata(pdev, priv);
  	return 0;
  }
  
  static int serial8250_em_remove(struct platform_device *pdev)
  {
  	struct serial8250_em_priv *priv = platform_get_drvdata(pdev);
  
  	serial8250_unregister_port(priv->line);
  	clk_disable_unprepare(priv->sclk);
  	return 0;
  }
  
  static const struct of_device_id serial8250_em_dt_ids[] = {
  	{ .compatible = "renesas,em-uart", },
  	{},
  };
  MODULE_DEVICE_TABLE(of, serial8250_em_dt_ids);
  
  static struct platform_driver serial8250_em_platform_driver = {
  	.driver = {
  		.name		= "serial8250-em",
  		.of_match_table = serial8250_em_dt_ids,
  		.owner		= THIS_MODULE,
  	},
  	.probe			= serial8250_em_probe,
  	.remove			= serial8250_em_remove,
  };
  
  module_platform_driver(serial8250_em_platform_driver);
  
  MODULE_AUTHOR("Magnus Damm");
  MODULE_DESCRIPTION("Renesas Emma Mobile 8250 Driver");
  MODULE_LICENSE("GPL v2");
  