serial.c

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/*
 * TI DaVinci serial driver
 *
 * Copyright (C) 2006 Texas Instruments.
 *
 * 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, or
 * (at your option) any later version.
 *
 * 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., 675 Mass Ave, Cambridge, MA 02139, USA.
 *
 */

#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/serial_8250.h>
#include <linux/serial_reg.h>
#include <linux/platform_device.h>
#include <linux/delay.h>
#include <linux/clk.h>
#include <linux/io.h>

#include <mach/serial.h>
#include <mach/cputype.h>

static inline unsigned int serial_read_reg(struct plat_serial8250_port *up,
                       int offset)
{
    offset <<= up->regshift;

    WARN_ONCE(!up->membase, "unmapped read: uart[%d]\n", offset);

    return (unsigned int)__raw_readl(up->membase + offset);
}

static inline void serial_write_reg(struct plat_serial8250_port *p, int offset,
                    int value)
{
    offset <<= p->regshift;

    WARN_ONCE(!p->membase, "unmapped write: uart[%d]\n", offset);

    __raw_writel(value, p->membase + offset);
}

static void __init davinci_serial_reset(struct plat_serial8250_port *p)
{
    unsigned int pwremu = 0;

    serial_write_reg(p, UART_IER, 0);  /* disable all interrupts */

    /* reset both transmitter and receiver: bits 14,13 = UTRST, URRST */
    serial_write_reg(p, UART_DAVINCI_PWREMU, pwremu);
    mdelay(10);

    pwremu |= (0x3 << 13);
    pwremu |= 0x1;
    serial_write_reg(p, UART_DAVINCI_PWREMU, pwremu);

    if (cpu_is_davinci_dm646x())
        serial_write_reg(p, UART_DM646X_SCR,
                 UART_DM646X_SCR_TX_WATERMARK);
}

int __init davinci_serial_init(struct davinci_uart_config *info)
{
    int i;
    char name[16];
    struct clk *uart_clk;
    struct davinci_soc_info *soc_info = &davinci_soc_info;
    struct device *dev = &soc_info->serial_dev->dev;
    struct plat_serial8250_port *p = dev->platform_data;

    /*
     * Make sure the serial ports are muxed on at this point.
     * You have to mux them off in device drivers later on if not needed.
     */
    for (i = 0; p->flags; i++, p++) {
        if (!(info->enabled_uarts & (1 << i)))
            continue;

        sprintf(name, "uart%d", i);
        uart_clk = clk_get(dev, name);
        if (IS_ERR(uart_clk)) {
            printk(KERN_ERR "%s:%d: failed to get UART%d clock\n",
                    __func__, __LINE__, i);
            continue;
        }

        clk_enable(uart_clk);
        p->uartclk = clk_get_rate(uart_clk);

        if (!p->membase && p->mapbase) {
            p->membase = ioremap(p->mapbase, SZ_4K);

            if (p->membase)
                p->flags &= ~UPF_IOREMAP;
            else
                pr_err("uart regs ioremap failed\n");
        }

        if (p->membase && p->type != PORT_AR7)
            davinci_serial_reset(p);
    }

    return platform_device_register(soc_info->serial_dev);
}