/*
 * OMAP7xx SPI 100k controller driver
 * Author: Fabrice Crohas <fcrohas@gmail.com>
 * from original omap1_mcspi driver
 *
 * Copyright (C) 2005, 2006 Nokia Corporation
 * Author:      Samuel Ortiz <samuel.ortiz@nokia.com> and
 *              Juha Yrj�l� <juha.yrjola@nokia.com>
 *
 * 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., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
 *
 */
#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/interrupt.h>
#include <linux/module.h>
#include <linux/device.h>
#include <linux/delay.h>
#include <linux/platform_device.h>
#include <linux/err.h>
#include <linux/clk.h>
#include <linux/io.h>
#include <linux/gpio.h>
#include <linux/slab.h>

#include <linux/spi/spi.h>

#include <plat/clock.h>

#define OMAP1_SPI100K_MAX_FREQ          48000000

#define ICR_SPITAS      (OMAP7XX_ICR_BASE + 0x12)

#define SPI_SETUP1      0x00
#define SPI_SETUP2      0x02
#define SPI_CTRL        0x04
#define SPI_STATUS      0x06
#define SPI_TX_LSB      0x08
#define SPI_TX_MSB      0x0a
#define SPI_RX_LSB      0x0c
#define SPI_RX_MSB      0x0e

#define SPI_SETUP1_INT_READ_ENABLE      (1UL << 5)
#define SPI_SETUP1_INT_WRITE_ENABLE     (1UL << 4)
#define SPI_SETUP1_CLOCK_DIVISOR(x)     ((x) << 1)
#define SPI_SETUP1_CLOCK_ENABLE         (1UL << 0)

#define SPI_SETUP2_ACTIVE_EDGE_FALLING  (0UL << 0)
#define SPI_SETUP2_ACTIVE_EDGE_RISING   (1UL << 0)
#define SPI_SETUP2_NEGATIVE_LEVEL       (0UL << 5)
#define SPI_SETUP2_POSITIVE_LEVEL       (1UL << 5)
#define SPI_SETUP2_LEVEL_TRIGGER        (0UL << 10)
#define SPI_SETUP2_EDGE_TRIGGER         (1UL << 10)

#define SPI_CTRL_SEN(x)                 ((x) << 7)
#define SPI_CTRL_WORD_SIZE(x)           (((x) - 1) << 2)
#define SPI_CTRL_WR                     (1UL << 1)
#define SPI_CTRL_RD                     (1UL << 0)

#define SPI_STATUS_WE                   (1UL << 1)
#define SPI_STATUS_RD                   (1UL << 0)

#define WRITE 0
#define READ  1


/* use PIO for small transfers, avoiding DMA setup/teardown overhead and
 * cache operations; better heuristics consider wordsize and bitrate.
 */
#define DMA_MIN_BYTES                   8

#define SPI_RUNNING     0
#define SPI_SHUTDOWN    1

struct omap1_spi100k {
        struct work_struct      work;

        /* lock protects queue and registers */
        spinlock_t              lock;
        struct list_head        msg_queue;
        struct spi_master       *master;
        struct clk              *ick;
        struct clk              *fck;

        /* Virtual base address of the controller */
        void __iomem            *base;

        /* State of the SPI */
        unsigned int            state;
};

struct omap1_spi100k_cs {
        void __iomem            *base;
        int                     word_len;
};

static struct workqueue_struct *omap1_spi100k_wq;

#define MOD_REG_BIT(val, mask, set) do { \
        if (set) \
                val |= mask; \
        else \
                val &= ~mask; \
} while (0)

static void spi100k_enable_clock(struct spi_master *master)
{
        unsigned int val;
        struct omap1_spi100k *spi100k = spi_master_get_devdata(master);

        /* enable SPI */
        val = readw(spi100k->base + SPI_SETUP1);
        val |= SPI_SETUP1_CLOCK_ENABLE;
        writew(val, spi100k->base + SPI_SETUP1);
}

static void spi100k_disable_clock(struct spi_master *master)
{
        unsigned int val;
        struct omap1_spi100k *spi100k = spi_master_get_devdata(master);

        /* disable SPI */
        val = readw(spi100k->base + SPI_SETUP1);
        val &= ~SPI_SETUP1_CLOCK_ENABLE;
        writew(val, spi100k->base + SPI_SETUP1);
}

static void spi100k_write_data(struct spi_master *master, int len, int data)
{
        struct omap1_spi100k *spi100k = spi_master_get_devdata(master);

        /* write 16-bit word, shifting 8-bit data if necessary */
        if (len <= 8) {
                data <<= 8;
                len = 16;
        }

        spi100k_enable_clock(master);
        writew( data , spi100k->base + SPI_TX_MSB);

        writew(SPI_CTRL_SEN(0) |
               SPI_CTRL_WORD_SIZE(len) |
               SPI_CTRL_WR,
               spi100k->base + SPI_CTRL);

        /* Wait for bit ack send change */
        while((readw(spi100k->base + SPI_STATUS) & SPI_STATUS_WE) != SPI_STATUS_WE);
        udelay(1000);

        spi100k_disable_clock(master);
}

static int spi100k_read_data(struct spi_master *master, int len)
{
        int dataH,dataL;
        struct omap1_spi100k *spi100k = spi_master_get_devdata(master);

        /* Always do at least 16 bits */
        if (len <= 8)
                len = 16;

        spi100k_enable_clock(master);
        writew(SPI_CTRL_SEN(0) |
               SPI_CTRL_WORD_SIZE(len) |
               SPI_CTRL_RD,
               spi100k->base + SPI_CTRL);

        while((readw(spi100k->base + SPI_STATUS) & SPI_STATUS_RD) != SPI_STATUS_RD);
        udelay(1000);

        dataL = readw(spi100k->base + SPI_RX_LSB);
        dataH = readw(spi100k->base + SPI_RX_MSB);
        spi100k_disable_clock(master);

        return dataL;
}

static void spi100k_open(struct spi_master *master)
{
        /* get control of SPI */
        struct omap1_spi100k *spi100k = spi_master_get_devdata(master);

        writew(SPI_SETUP1_INT_READ_ENABLE |
               SPI_SETUP1_INT_WRITE_ENABLE |
               SPI_SETUP1_CLOCK_DIVISOR(0), spi100k->base + SPI_SETUP1);

        /* configure clock and interrupts */
        writew(SPI_SETUP2_ACTIVE_EDGE_FALLING |
               SPI_SETUP2_NEGATIVE_LEVEL |
               SPI_SETUP2_LEVEL_TRIGGER, spi100k->base + SPI_SETUP2);
}

static void omap1_spi100k_force_cs(struct omap1_spi100k *spi100k, int enable)
{
        if (enable)
                writew(0x05fc, spi100k->base + SPI_CTRL);
        else
                writew(0x05fd, spi100k->base + SPI_CTRL);
}

static unsigned
omap1_spi100k_txrx_pio(struct spi_device *spi, struct spi_transfer *xfer)
{
        struct omap1_spi100k    *spi100k;
        struct omap1_spi100k_cs *cs = spi->controller_state;
        unsigned int            count, c;
        int                     word_len;

        spi100k = spi_master_get_devdata(spi->master);
        count = xfer->len;
        c = count;
        word_len = cs->word_len;

        if (word_len <= 8) {
                u8              *rx;
                const u8        *tx;

                rx = xfer->rx_buf;
                tx = xfer->tx_buf;
                do {
                        c-=1;
                        if (xfer->tx_buf != NULL)
                                spi100k_write_data(spi->master, word_len, *tx++);
                        if (xfer->rx_buf != NULL)
                                *rx++ = spi100k_read_data(spi->master, word_len);
                } while(c);
        } else if (word_len <= 16) {
                u16             *rx;
                const u16       *tx;

                rx = xfer->rx_buf;
                tx = xfer->tx_buf;
                do {
                        c-=2;
                        if (xfer->tx_buf != NULL)
                                spi100k_write_data(spi->master,word_len, *tx++);
                        if (xfer->rx_buf != NULL)
                                *rx++ = spi100k_read_data(spi->master,word_len);
                } while(c);
        } else if (word_len <= 32) {
                u32             *rx;
                const u32       *tx;

                rx = xfer->rx_buf;
                tx = xfer->tx_buf;
                do {
                        c-=4;
                        if (xfer->tx_buf != NULL)
                                spi100k_write_data(spi->master,word_len, *tx);
                        if (xfer->rx_buf != NULL)
                                *rx = spi100k_read_data(spi->master,word_len);
                } while(c);
        }
        return count - c;
}

/* called only when no transfer is active to this device */
static int omap1_spi100k_setup_transfer(struct spi_device *spi,
                struct spi_transfer *t)
{
        struct omap1_spi100k *spi100k = spi_master_get_devdata(spi->master);
        struct omap1_spi100k_cs *cs = spi->controller_state;
        u8 word_len = spi->bits_per_word;

        if (t != NULL && t->bits_per_word)
                word_len = t->bits_per_word;
        if (!word_len)
                word_len = 8;

        if (spi->bits_per_word > 32)
                return -EINVAL;
        cs->word_len = word_len;

        /* SPI init before transfer */
        writew(0x3e , spi100k->base + SPI_SETUP1);
        writew(0x00 , spi100k->base + SPI_STATUS);
        writew(0x3e , spi100k->base + SPI_CTRL);

        return 0;
}

/* the spi->mode bits understood by this driver: */
#define MODEBITS (SPI_CPOL | SPI_CPHA | SPI_CS_HIGH)

static int omap1_spi100k_setup(struct spi_device *spi)
{
        int                     ret;
        struct omap1_spi100k    *spi100k;
        struct omap1_spi100k_cs *cs = spi->controller_state;

        if (spi->bits_per_word < 4 || spi->bits_per_word > 32) {
                 dev_dbg(&spi->dev, "setup: unsupported %d bit words\n",
                        spi->bits_per_word);
                 return -EINVAL;
        }

        spi100k = spi_master_get_devdata(spi->master);

        if (!cs) {
                cs = kzalloc(sizeof *cs, GFP_KERNEL);
                if (!cs)
                        return -ENOMEM;
                cs->base = spi100k->base + spi->chip_select * 0x14;
                spi->controller_state = cs;
        }

        spi100k_open(spi->master);

        clk_enable(spi100k->ick);
        clk_enable(spi100k->fck);

        ret = omap1_spi100k_setup_transfer(spi, NULL);

        clk_disable(spi100k->ick);
        clk_disable(spi100k->fck);

        return ret;
}

static void omap1_spi100k_work(struct work_struct *work)
{
        struct omap1_spi100k    *spi100k;
        int status = 0;

        spi100k = container_of(work, struct omap1_spi100k, work);
        spin_lock_irq(&spi100k->lock);

        clk_enable(spi100k->ick);
        clk_enable(spi100k->fck);

        /* We only enable one channel at a time -- the one whose message is
         * at the head of the queue -- although this controller would gladly
         * arbitrate among multiple channels.  This corresponds to "single
         * channel" master mode.  As a side effect, we need to manage the
         * chipselect with the FORCE bit ... CS != channel enable.
         */
         while (!list_empty(&spi100k->msg_queue)) {
                struct spi_message              *m;
                struct spi_device               *spi;
                struct spi_transfer             *t = NULL;
                int                             cs_active = 0;
                struct omap1_spi100k_cs         *cs;
                int                             par_override = 0;

                m = container_of(spi100k->msg_queue.next, struct spi_message,
                                 queue);

                list_del_init(&m->queue);
                spin_unlock_irq(&spi100k->lock);

                spi = m->spi;
                cs = spi->controller_state;

                list_for_each_entry(t, &m->transfers, transfer_list) {
                        if (t->tx_buf == NULL && t->rx_buf == NULL && t->len) {
                                status = -EINVAL;
                                break;
                        }
                        if (par_override || t->speed_hz || t->bits_per_word) {
                                par_override = 1;
                                status = omap1_spi100k_setup_transfer(spi, t);
                                if (status < 0)
                                        break;
                                if (!t->speed_hz && !t->bits_per_word)
                                        par_override = 0;
                        }

                        if (!cs_active) {
                                omap1_spi100k_force_cs(spi100k, 1);
                                cs_active = 1;
                        }

                        if (t->len) {
                                unsigned count;

                                count = omap1_spi100k_txrx_pio(spi, t);
                                m->actual_length += count;

                                if (count != t->len) {
                                        status = -EIO;
                                        break;
                                }
                        }

                        if (t->delay_usecs)
                                udelay(t->delay_usecs);

                        /* ignore the "leave it on after last xfer" hint */

                        if (t->cs_change) {
                                omap1_spi100k_force_cs(spi100k, 0);
                                cs_active = 0;
                        }
                }

                /* Restore defaults if they were overriden */
                if (par_override) {
                        par_override = 0;
                        status = omap1_spi100k_setup_transfer(spi, NULL);
                }

                if (cs_active)
                        omap1_spi100k_force_cs(spi100k, 0);

                m->status = status;
                m->complete(m->context);

                spin_lock_irq(&spi100k->lock);
        }

        clk_disable(spi100k->ick);
        clk_disable(spi100k->fck);
        spin_unlock_irq(&spi100k->lock);

        if (status < 0)
                printk(KERN_WARNING "spi transfer failed with %d\n", status);
}

static int omap1_spi100k_transfer(struct spi_device *spi, struct spi_message *m)
{
        struct omap1_spi100k    *spi100k;
        unsigned long           flags;
        struct spi_transfer     *t;

        m->actual_length = 0;
        m->status = -EINPROGRESS;

        spi100k = spi_master_get_devdata(spi->master);

        /* Don't accept new work if we're shutting down */
        if (spi100k->state == SPI_SHUTDOWN)
                return -ESHUTDOWN;

        /* reject invalid messages and transfers */
        if (list_empty(&m->transfers) || !m->complete)
                return -EINVAL;

        list_for_each_entry(t, &m->transfers, transfer_list) {
                const void      *tx_buf = t->tx_buf;
                void            *rx_buf = t->rx_buf;
                unsigned        len = t->len;

                if (t->speed_hz > OMAP1_SPI100K_MAX_FREQ
                                || (len && !(rx_buf || tx_buf))
                                || (t->bits_per_word &&
                                        (  t->bits_per_word < 4
                                        || t->bits_per_word > 32))) {
                        dev_dbg(&spi->dev, "transfer: %d Hz, %d %s%s, %d bpw\n",
                                        t->speed_hz,
                                        len,
                                        tx_buf ? "tx" : "",
                                        rx_buf ? "rx" : "",
                                        t->bits_per_word);
                        return -EINVAL;
                }

                if (t->speed_hz && t->speed_hz < OMAP1_SPI100K_MAX_FREQ/(1<<16)) {
                        dev_dbg(&spi->dev, "%d Hz max exceeds %d\n",
                                        t->speed_hz,
                                        OMAP1_SPI100K_MAX_FREQ/(1<<16));
                        return -EINVAL;
                }

        }

        spin_lock_irqsave(&spi100k->lock, flags);
        list_add_tail(&m->queue, &spi100k->msg_queue);
        queue_work(omap1_spi100k_wq, &spi100k->work);
        spin_unlock_irqrestore(&spi100k->lock, flags);

        return 0;
}

static int __init omap1_spi100k_reset(struct omap1_spi100k *spi100k)
{
        return 0;
}

static int __devinit omap1_spi100k_probe(struct platform_device *pdev)
{
        struct spi_master       *master;
        struct omap1_spi100k    *spi100k;
        int                     status = 0;

        if (!pdev->id)
                return -EINVAL;

        master = spi_alloc_master(&pdev->dev, sizeof *spi100k);
        if (master == NULL) {
                dev_dbg(&pdev->dev, "master allocation failed\n");
                return -ENOMEM;
        }

        if (pdev->id != -1)
               master->bus_num = pdev->id;

        master->setup = omap1_spi100k_setup;
        master->transfer = omap1_spi100k_transfer;
        master->cleanup = NULL;
        master->num_chipselect = 2;
        master->mode_bits = MODEBITS;

        dev_set_drvdata(&pdev->dev, master);

        spi100k = spi_master_get_devdata(master);
        spi100k->master = master;

        /*
         * The memory region base address is taken as the platform_data.
         * You should allocate this with ioremap() before initializing
         * the SPI.
         */
        spi100k->base = (void __iomem *) pdev->dev.platform_data;

        INIT_WORK(&spi100k->work, omap1_spi100k_work);

        spin_lock_init(&spi100k->lock);
        INIT_LIST_HEAD(&spi100k->msg_queue);
        spi100k->ick = clk_get(&pdev->dev, "ick");
        if (IS_ERR(spi100k->ick)) {
                dev_dbg(&pdev->dev, "can't get spi100k_ick\n");
                status = PTR_ERR(spi100k->ick);
                goto err1;
        }

        spi100k->fck = clk_get(&pdev->dev, "fck");
        if (IS_ERR(spi100k->fck)) {
                dev_dbg(&pdev->dev, "can't get spi100k_fck\n");
                status = PTR_ERR(spi100k->fck);
                goto err2;
        }

        if (omap1_spi100k_reset(spi100k) < 0)
                goto err3;

        status = spi_register_master(master);
        if (status < 0)
                goto err3;

        spi100k->state = SPI_RUNNING;

        return status;

err3:
        clk_put(spi100k->fck);
err2:
        clk_put(spi100k->ick);
err1:
        spi_master_put(master);
        return status;
}

static int __exit omap1_spi100k_remove(struct platform_device *pdev)
{
        struct spi_master       *master;
        struct omap1_spi100k    *spi100k;
        struct resource         *r;
        unsigned                limit = 500;
        unsigned long           flags;
        int                     status = 0;

        master = dev_get_drvdata(&pdev->dev);
        spi100k = spi_master_get_devdata(master);

        spin_lock_irqsave(&spi100k->lock, flags);

        spi100k->state = SPI_SHUTDOWN;
        while (!list_empty(&spi100k->msg_queue) && limit--) {
                spin_unlock_irqrestore(&spi100k->lock, flags);
                msleep(10);
                spin_lock_irqsave(&spi100k->lock, flags);
        }

        if (!list_empty(&spi100k->msg_queue))
                status = -EBUSY;

        spin_unlock_irqrestore(&spi100k->lock, flags);

        if (status != 0)
                return status;

        clk_put(spi100k->fck);
        clk_put(spi100k->ick);

        r = platform_get_resource(pdev, IORESOURCE_MEM, 0);

        spi_unregister_master(master);

        return 0;
}

static struct platform_driver omap1_spi100k_driver = {
        .driver = {
                .name           = "omap1_spi100k",
                .owner          = THIS_MODULE,
        },
        .remove         = __exit_p(omap1_spi100k_remove),
};


static int __init omap1_spi100k_init(void)
{
        omap1_spi100k_wq = create_singlethread_workqueue(
                        omap1_spi100k_driver.driver.name);

        if (omap1_spi100k_wq == NULL)
                return -1;

        return platform_driver_probe(&omap1_spi100k_driver, omap1_spi100k_probe);
}

static void __exit omap1_spi100k_exit(void)
{
        platform_driver_unregister(&omap1_spi100k_driver);

        destroy_workqueue(omap1_spi100k_wq);
}

module_init(omap1_spi100k_init);
module_exit(omap1_spi100k_exit);

MODULE_DESCRIPTION("OMAP7xx SPI 100k controller driver");
MODULE_AUTHOR("Fabrice Crohas <fcrohas@gmail.com>");
MODULE_LICENSE("GPL");