/*
 * AVR power-management chip interface for the Buffalo Linkstation /
 * Kurobox Platform.
 *
 * Author: 2006 (c) G. Liakhovetski
 *       g.liakhovetski@gmx.de
 *
 * This file is licensed under the terms of the GNU General Public License
 * version 2.  This program is licensed "as is" without any warranty of
 * any kind, whether express or implied.
 */
#include <linux/workqueue.h>
#include <linux/string.h>
#include <linux/delay.h>
#include <linux/serial_reg.h>
#include <linux/serial_8250.h>
#include <linux/of.h>
#include <linux/of_address.h>
#include <asm/io.h>
#include <asm/termbits.h>

#include "mpc10x.h"

static void __iomem *avr_addr;
static unsigned long avr_clock;

static struct work_struct wd_work;

static void wd_stop(struct work_struct *unused)
{
        const char string[] = "AAAAFFFFJJJJ>>>>VVVV>>>>ZZZZVVVVKKKK";
        int i = 0, rescue = 8;
        int len = strlen(string);

        while (rescue--) {
                int j;
                char lsr = in_8(avr_addr + UART_LSR);

                if (lsr & (UART_LSR_THRE | UART_LSR_TEMT)) {
                        for (j = 0; j < 16 && i < len; j++, i++)
                                out_8(avr_addr + UART_TX, string[i]);
                        if (i == len) {
                                /* Read "OK" back: 4ms for the last "KKKK"
                                   plus a couple bytes back */
                                msleep(7);
                                printk("linkstation: disarming the AVR watchdog: ");
                                while (in_8(avr_addr + UART_LSR) & UART_LSR_DR)
                                        printk("%c", in_8(avr_addr + UART_RX));
                                break;
                        }
                }
                msleep(17);
        }
        printk("\n");
}

#define AVR_QUOT(clock) ((clock) + 8 * 9600) / (16 * 9600)

void avr_uart_configure(void)
{
        unsigned char cval = UART_LCR_WLEN8;
        unsigned int quot = AVR_QUOT(avr_clock);

        if (!avr_addr || !avr_clock)
                return;

        out_8(avr_addr + UART_LCR, cval);                       /* initialise UART */
        out_8(avr_addr + UART_MCR, 0);
        out_8(avr_addr + UART_IER, 0);

        cval |= UART_LCR_STOP | UART_LCR_PARITY | UART_LCR_EPAR;

        out_8(avr_addr + UART_LCR, cval);                       /* Set character format */

        out_8(avr_addr + UART_LCR, cval | UART_LCR_DLAB);       /* set DLAB */
        out_8(avr_addr + UART_DLL, quot & 0xff);                /* LS of divisor */
        out_8(avr_addr + UART_DLM, quot >> 8);                  /* MS of divisor */
        out_8(avr_addr + UART_LCR, cval);                       /* reset DLAB */
        out_8(avr_addr + UART_FCR, UART_FCR_ENABLE_FIFO);       /* enable FIFO */
}

void avr_uart_send(const char c)
{
        if (!avr_addr || !avr_clock)
                return;

        out_8(avr_addr + UART_TX, c);
        out_8(avr_addr + UART_TX, c);
        out_8(avr_addr + UART_TX, c);
        out_8(avr_addr + UART_TX, c);
}

static void __init ls_uart_init(void)
{
        local_irq_disable();

#ifndef CONFIG_SERIAL_8250
        out_8(avr_addr + UART_FCR, UART_FCR_ENABLE_FIFO);       /* enable FIFO */
        out_8(avr_addr + UART_FCR, UART_FCR_ENABLE_FIFO |
              UART_FCR_CLEAR_RCVR | UART_FCR_CLEAR_XMIT);       /* clear FIFOs */
        out_8(avr_addr + UART_FCR, 0);
        out_8(avr_addr + UART_IER, 0);

        /* Clear up interrupts */
        (void) in_8(avr_addr + UART_LSR);
        (void) in_8(avr_addr + UART_RX);
        (void) in_8(avr_addr + UART_IIR);
        (void) in_8(avr_addr + UART_MSR);
#endif
        avr_uart_configure();

        local_irq_enable();
}

static int __init ls_uarts_init(void)
{
        struct device_node *avr;
        struct resource res;
        int len, ret;

        avr = of_find_node_by_path("/soc10x/serial@80004500");
        if (!avr)
                return -EINVAL;

        avr_clock = *(u32*)of_get_property(avr, "clock-frequency", &len);
        if (!avr_clock)
                return -EINVAL;

        ret = of_address_to_resource(avr, 0, &res);
        if (ret)
                return ret;

        of_node_put(avr);

        avr_addr = ioremap(res.start, 32);
        if (!avr_addr)
                return -EFAULT;

        ls_uart_init();

        INIT_WORK(&wd_work, wd_stop);
        schedule_work(&wd_work);

        return 0;
}

machine_late_initcall(linkstation, ls_uarts_init);