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* Sequencer Serial Port (SSP) based SPI master driver
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* Copyright (C) 2010 Texas Instruments Inc
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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#include <linux/kernel.h>
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#include <linux/err.h>
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#include <linux/completion.h>
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#include <linux/delay.h>
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#include <linux/module.h>
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#include <linux/platform_device.h>
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#include <linux/spi/spi.h>
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#include <linux/mfd/ti_ssp.h>
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#define MODE_BITS (SPI_CPHA | SPI_CPOL | SPI_CS_HIGH)
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struct spi_master *master;
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struct list_head msg_queue;
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struct completion complete;
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struct workqueue_struct *workqueue;
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struct work_struct work;
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u32 pc_en, pc_dis, pc_wr, pc_rd;
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void (*select)(int cs);
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static u32 ti_ssp_spi_rx(struct ti_ssp_spi *hw)
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ti_ssp_run(hw->dev, hw->pc_rd, 0, &ret);
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static void ti_ssp_spi_tx(struct ti_ssp_spi *hw, u32 data)
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ti_ssp_run(hw->dev, hw->pc_wr, data << (32 - hw->bpw), NULL);
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static int ti_ssp_spi_txrx(struct ti_ssp_spi *hw, struct spi_message *msg,
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struct spi_transfer *t)
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const u8 *tx = t->tx_buf;
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for (count = 0; count < t->len; count += 1) {
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ti_ssp_spi_tx(hw, *tx++);
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*rx++ = ti_ssp_spi_rx(hw);
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} else if (hw->bpw <= 16) {
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const u16 *tx = t->tx_buf;
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for (count = 0; count < t->len; count += 2) {
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ti_ssp_spi_tx(hw, *tx++);
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*rx++ = ti_ssp_spi_rx(hw);
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const u32 *tx = t->tx_buf;
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for (count = 0; count < t->len; count += 4) {
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ti_ssp_spi_tx(hw, *tx++);
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*rx++ = ti_ssp_spi_rx(hw);
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msg->actual_length += count; /* bytes transferred */
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dev_dbg(&msg->spi->dev, "xfer %s%s, %d bytes, %d bpw, count %d%s\n",
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t->tx_buf ? "tx" : "", t->rx_buf ? "rx" : "", t->len,
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hw->bpw, count, (count < t->len) ? " (under)" : "");
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return (count < t->len) ? -EIO : 0; /* left over data */
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static void ti_ssp_spi_chip_select(struct ti_ssp_spi *hw, int cs_active)
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cs_active = !!cs_active;
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if (cs_active == hw->cs_active)
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ti_ssp_run(hw->dev, cs_active ? hw->pc_en : hw->pc_dis, 0, NULL);
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hw->cs_active = cs_active;
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#define __SHIFT_OUT(bits) (SSP_OPCODE_SHIFT | SSP_OUT_MODE | \
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cs_en | clk | SSP_COUNT((bits) * 2 - 1))
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#define __SHIFT_IN(bits) (SSP_OPCODE_SHIFT | SSP_IN_MODE | \
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cs_en | clk | SSP_COUNT((bits) * 2 - 1))
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static int ti_ssp_spi_setup_transfer(struct ti_ssp_spi *hw, u8 bpw, u8 mode)
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u32 cs_en, cs_dis, clk;
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u32 topbits, botbits;
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if (mode == hw->mode && bpw == hw->bpw)
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cs_en = (mode & SPI_CS_HIGH) ? SSP_CS_HIGH : SSP_CS_LOW;
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cs_dis = (mode & SPI_CS_HIGH) ? SSP_CS_LOW : SSP_CS_HIGH;
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clk = (mode & SPI_CPOL) ? SSP_CLK_HIGH : SSP_CLK_LOW;
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/* Construct instructions */
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/* Disable Chip Select */
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seqram[idx++] = SSP_OPCODE_DIRECT | SSP_OUT_MODE | cs_dis | clk;
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seqram[idx++] = SSP_OPCODE_STOP | SSP_OUT_MODE | cs_dis | clk;
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/* Enable Chip Select */
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seqram[idx++] = SSP_OPCODE_DIRECT | SSP_OUT_MODE | cs_en | clk;
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seqram[idx++] = SSP_OPCODE_STOP | SSP_OUT_MODE | cs_en | clk;
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/* Reads and writes need to be split for bpw > 16 */
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topbits = (bpw > 16) ? 16 : bpw;
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botbits = bpw - topbits;
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seqram[idx++] = __SHIFT_OUT(topbits) | SSP_ADDR_REG;
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seqram[idx++] = __SHIFT_OUT(botbits) | SSP_DATA_REG;
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seqram[idx++] = SSP_OPCODE_STOP | SSP_OUT_MODE | cs_en | clk;
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seqram[idx++] = __SHIFT_IN(botbits) | SSP_ADDR_REG;
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seqram[idx++] = __SHIFT_IN(topbits) | SSP_DATA_REG;
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seqram[idx++] = SSP_OPCODE_STOP | SSP_OUT_MODE | cs_en | clk;
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error = ti_ssp_load(hw->dev, 0, seqram, idx);
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error = ti_ssp_set_mode(hw->dev, ((mode & SPI_CPHA) ?
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static void ti_ssp_spi_work(struct work_struct *work)
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struct ti_ssp_spi *hw = container_of(work, struct ti_ssp_spi, work);
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spin_lock(&hw->lock);
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while (!list_empty(&hw->msg_queue)) {
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struct spi_message *m;
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struct spi_device *spi;
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struct spi_transfer *t = NULL;
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m = container_of(hw->msg_queue.next, struct spi_message,
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list_del_init(&m->queue);
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spin_unlock(&hw->lock);
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hw->select(spi->chip_select);
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list_for_each_entry(t, &m->transfers, transfer_list) {
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int bpw = spi->bits_per_word;
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if (t->bits_per_word)
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bpw = t->bits_per_word;
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if (ti_ssp_spi_setup_transfer(hw, bpw, spi->mode) < 0)
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ti_ssp_spi_chip_select(hw, 1);
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xfer_status = ti_ssp_spi_txrx(hw, m, t);
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status = xfer_status;
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udelay(t->delay_usecs);
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ti_ssp_spi_chip_select(hw, 0);
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ti_ssp_spi_chip_select(hw, 0);
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m->complete(m->context);
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spin_lock(&hw->lock);
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complete(&hw->complete);
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spin_unlock(&hw->lock);
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static int ti_ssp_spi_setup(struct spi_device *spi)
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if (spi->bits_per_word > 32)
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static int ti_ssp_spi_transfer(struct spi_device *spi, struct spi_message *m)
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struct ti_ssp_spi *hw;
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struct spi_transfer *t;
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m->actual_length = 0;
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m->status = -EINPROGRESS;
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hw = spi_master_get_devdata(spi->master);
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if (list_empty(&m->transfers) || !m->complete)
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list_for_each_entry(t, &m->transfers, transfer_list) {
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if (t->len && !(t->rx_buf || t->tx_buf)) {
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dev_err(&spi->dev, "invalid xfer, no buffer\n");
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if (t->len && t->rx_buf && t->tx_buf) {
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dev_err(&spi->dev, "invalid xfer, full duplex\n");
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if (t->bits_per_word > 32) {
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dev_err(&spi->dev, "invalid xfer width %d\n",
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spin_lock(&hw->lock);
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list_add_tail(&m->queue, &hw->msg_queue);
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queue_work(hw->workqueue, &hw->work);
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spin_unlock(&hw->lock);
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static int __devinit ti_ssp_spi_probe(struct platform_device *pdev)
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const struct ti_ssp_spi_data *pdata;
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struct ti_ssp_spi *hw;
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struct spi_master *master;
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struct device *dev = &pdev->dev;
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pdata = dev->platform_data;
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dev_err(dev, "platform data not found\n");
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master = spi_alloc_master(dev, sizeof(struct ti_ssp_spi));
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dev_err(dev, "cannot allocate SPI master\n");
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hw = spi_master_get_devdata(master);
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platform_set_drvdata(pdev, hw);
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hw->select = pdata->select;
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spin_lock_init(&hw->lock);
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init_completion(&hw->complete);
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INIT_LIST_HEAD(&hw->msg_queue);
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INIT_WORK(&hw->work, ti_ssp_spi_work);
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hw->workqueue = create_singlethread_workqueue(dev_name(dev));
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if (!hw->workqueue) {
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dev_err(dev, "work queue creation failed\n");
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error = ti_ssp_set_iosel(hw->dev, pdata->iosel);
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dev_err(dev, "io setup failed\n");
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master->bus_num = pdev->id;
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master->num_chipselect = pdata->num_cs;
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master->mode_bits = MODE_BITS;
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master->flags = SPI_MASTER_HALF_DUPLEX;
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master->setup = ti_ssp_spi_setup;
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master->transfer = ti_ssp_spi_transfer;
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error = spi_register_master(master);
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dev_err(dev, "master registration failed\n");
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destroy_workqueue(hw->workqueue);
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spi_master_put(master);
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static int __devexit ti_ssp_spi_remove(struct platform_device *pdev)
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struct ti_ssp_spi *hw = platform_get_drvdata(pdev);
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while (!list_empty(&hw->msg_queue)) {
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error = wait_for_completion_interruptible(&hw->complete);
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destroy_workqueue(hw->workqueue);
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spi_unregister_master(hw->master);
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static struct platform_driver ti_ssp_spi_driver = {
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.probe = ti_ssp_spi_probe,
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.remove = __devexit_p(ti_ssp_spi_remove),
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.name = "ti-ssp-spi",
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.owner = THIS_MODULE,
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module_platform_driver(ti_ssp_spi_driver);
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MODULE_DESCRIPTION("SSP SPI Master");
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MODULE_AUTHOR("Cyril Chemparathy");
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MODULE_LICENSE("GPL");
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MODULE_ALIAS("platform:ti-ssp-spi");