8250_em.c

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/*
 * 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 __devinit 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 = -EINVAL;

    if (!regs || !irq) {
        dev_err(&pdev->dev, "missing registers or irq\n");
        goto err0;
    }

    priv = kzalloc(sizeof(*priv), GFP_KERNEL);
    if (!priv) {
        dev_err(&pdev->dev, "unable to allocate private data\n");
        ret = -ENOMEM;
        goto err0;
    }

    priv->sclk = clk_get(&pdev->dev, "sclk");
    if (IS_ERR(priv->sclk)) {
        dev_err(&pdev->dev, "unable to get clock\n");
        ret = PTR_ERR(priv->sclk);
        goto err1;
    }

    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_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");
        goto err2;
    }

    priv->line = ret;
    platform_set_drvdata(pdev, priv);
    return 0;

 err2:
    clk_disable(priv->sclk);
    clk_put(priv->sclk);
 err1:
    kfree(priv);
 err0:
    return ret;
}

static int __devexit serial8250_em_remove(struct platform_device *pdev)
{
    struct serial8250_em_priv *priv = platform_get_drvdata(pdev);

    serial8250_unregister_port(priv->line);
    clk_disable(priv->sclk);
    clk_put(priv->sclk);
    kfree(priv);
    return 0;
}

static const struct of_device_id serial8250_em_dt_ids[] __devinitconst = {
    { .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         = __devexit_p(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");