2011-08-24 10:19:23 +00:00
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/*
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* (C) Copyright 2011 - Franck JULLIEN <elec4fun@gmail.com>
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License as
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* published by the Free Software Foundation; either version 2 of
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* the License, or (at your option) any later version.
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*
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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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*
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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,
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* MA 02111-1307 USA
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*
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*/
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#include <common.h>
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#include <init.h>
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#include <driver.h>
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#include <spi/spi.h>
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2011-09-22 17:02:57 +00:00
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#include <io.h>
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2011-08-24 10:19:23 +00:00
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#include <asm/spi.h>
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#include <asm/nios2-io.h>
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2011-11-24 20:46:34 +00:00
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#include <clock.h>
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static void altera_spi_cs_inactive(struct spi_device *spi);
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2011-08-24 10:19:23 +00:00
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static int altera_spi_setup(struct spi_device *spi)
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{
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struct spi_master *master = spi->master;
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struct device_d spi_dev = spi->dev;
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struct altera_spi *altera_spi = container_of(master, struct altera_spi, master);
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if (spi->bits_per_word != altera_spi->databits) {
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dev_err(master->dev, " master doesn't support %d bits per word requested by %s\n",
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spi->bits_per_word, spi_dev.name);
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return -1;
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}
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if ((spi->mode & (SPI_CPHA | SPI_CPOL)) != altera_spi->mode) {
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dev_err(master->dev, " master doesn't support SPI_MODE%d requested by %s\n",
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spi->mode & (SPI_CPHA | SPI_CPOL), spi_dev.name);
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return -1;
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}
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if (spi->max_speed_hz < altera_spi->speed) {
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dev_err(master->dev, " frequency is too high for %s\n", spi_dev.name);
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return -1;
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}
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2011-11-24 20:46:34 +00:00
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altera_spi_cs_inactive(spi);
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2011-08-24 10:19:23 +00:00
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dev_dbg(master->dev, " mode 0x%08x, bits_per_word: %d, speed: %d\n",
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spi->mode, spi->bits_per_word, altera_spi->speed);
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return 0;
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}
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static unsigned int altera_spi_xchg_single(struct altera_spi *altera_spi, unsigned int data)
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{
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struct nios_spi *nios_spi = altera_spi->regs;
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while (!(readl(&nios_spi->status) & NIOS_SPI_TRDY));
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writel(data, &nios_spi->txdata);
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while (!(readl(&nios_spi->status) & NIOS_SPI_RRDY));
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return readl(&nios_spi->rxdata);
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}
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/*
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* When using SPI_CS_HIGH devices, only one device is allowed to be
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* connected to the Altera SPI master. This limitation is due to the
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* emulation of an active high CS by writing 0 to the slaveselect register
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* (this produce a '1' to all CS pins).
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*/
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static void altera_spi_cs_active(struct spi_device *spi)
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{
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struct altera_spi *altera_spi = container_of(spi->master, struct altera_spi, master);
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struct nios_spi *nios_spi = altera_spi->regs;
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uint32_t tmp;
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if (spi->mode & SPI_CS_HIGH) {
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tmp = readw(&nios_spi->control);
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writew(tmp & ~NIOS_SPI_SSO, &nios_spi->control);
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writel(0, &nios_spi->slaveselect);
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} else {
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writel(1 << spi->chip_select, &nios_spi->slaveselect);
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tmp = readl(&nios_spi->control);
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writel(tmp | NIOS_SPI_SSO, &nios_spi->control);
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}
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}
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static void altera_spi_cs_inactive(struct spi_device *spi)
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{
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struct altera_spi *altera_spi = container_of(spi->master, struct altera_spi, master);
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struct nios_spi *nios_spi = altera_spi->regs;
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uint32_t tmp;
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if (spi->mode & SPI_CS_HIGH) {
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writel(1 << spi->chip_select, &nios_spi->slaveselect);
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tmp = readl(&nios_spi->control);
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writel(tmp | NIOS_SPI_SSO, &nios_spi->control);
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} else {
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tmp = readw(&nios_spi->control);
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writew(tmp & ~NIOS_SPI_SSO, &nios_spi->control);
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}
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}
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static unsigned altera_spi_do_xfer(struct spi_device *spi, struct spi_transfer *t)
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{
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struct altera_spi *altera_spi = container_of(spi->master, struct altera_spi, master);
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int word_len = spi->bits_per_word;
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unsigned retval = 0;
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u32 txval;
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u32 rxval;
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word_len = spi->bits_per_word;
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if (word_len <= 8) {
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const u8 *txbuf = t->tx_buf;
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u8 *rxbuf = t->rx_buf;
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int i = 0;
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while (i < t->len) {
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txval = txbuf ? txbuf[i] : 0;
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rxval = altera_spi_xchg_single(altera_spi, txval);
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if (rxbuf)
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rxbuf[i] = rxval;
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i++;
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retval++;
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}
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} else if (word_len <= 16) {
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const u16 *txbuf = t->tx_buf;
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u16 *rxbuf = t->rx_buf;
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int i = 0;
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while (i < t->len >> 1) {
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txval = txbuf ? txbuf[i] : 0;
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rxval = altera_spi_xchg_single(altera_spi, txval);
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if (rxbuf)
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rxbuf[i] = rxval;
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i++;
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retval += 2;
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}
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} else if (word_len <= 32) {
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const u32 *txbuf = t->tx_buf;
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u32 *rxbuf = t->rx_buf;
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int i = 0;
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while (i < t->len >> 2) {
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txval = txbuf ? txbuf[i] : 0;
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rxval = altera_spi_xchg_single(altera_spi, txval);
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if (rxbuf)
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rxbuf[i] = rxval;
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i++;
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retval += 4;
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}
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}
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return retval;
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}
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static int altera_spi_transfer(struct spi_device *spi, struct spi_message *mesg)
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{
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struct altera_spi *altera_spi = container_of(spi->master, struct altera_spi, master);
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struct nios_spi *nios_spi = altera_spi->regs;
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struct spi_transfer *t;
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2011-11-24 20:46:34 +00:00
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unsigned int cs_change;
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const int nsecs = 50;
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2011-08-24 10:19:23 +00:00
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altera_spi_cs_active(spi);
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2011-11-24 20:46:34 +00:00
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cs_change = 0;
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2011-08-24 10:19:23 +00:00
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mesg->actual_length = 0;
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list_for_each_entry(t, &mesg->transfers, transfer_list) {
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2011-11-24 20:46:34 +00:00
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if (cs_change) {
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ndelay(nsecs);
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altera_spi_cs_inactive(spi);
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ndelay(nsecs);
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altera_spi_cs_active(spi);
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}
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cs_change = t->cs_change;
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2011-08-24 10:19:23 +00:00
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mesg->actual_length += altera_spi_do_xfer(spi, t);
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2011-11-24 20:46:34 +00:00
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if (cs_change) {
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altera_spi_cs_active(spi);
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}
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2011-08-24 10:19:23 +00:00
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}
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/* Wait the end of any pending transfer */
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while ((readl(&nios_spi->status) & NIOS_SPI_TMT) == 0);
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2011-11-24 20:46:34 +00:00
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if (!cs_change)
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altera_spi_cs_inactive(spi);
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2011-08-24 10:19:23 +00:00
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return 0;
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}
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static int altera_spi_probe(struct device_d *dev)
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{
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struct spi_master *master;
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struct altera_spi *altera_spi;
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struct spi_altera_master *pdata = dev->platform_data;
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struct nios_spi *nios_spi;
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altera_spi = xzalloc(sizeof(*altera_spi));
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master = &altera_spi->master;
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master->dev = dev;
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master->setup = altera_spi_setup;
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master->transfer = altera_spi_transfer;
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master->num_chipselect = pdata->num_chipselect;
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2011-11-24 20:46:34 +00:00
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master->bus_num = pdata->bus_num;
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2011-08-24 10:19:23 +00:00
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altera_spi->regs = dev_request_mem_region(dev, 0);
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altera_spi->databits = pdata->databits;
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altera_spi->speed = pdata->speed;
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altera_spi->mode = pdata->spi_mode;
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nios_spi = altera_spi->regs;
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writel(0, &nios_spi->slaveselect);
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writel(0, &nios_spi->control);
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spi_register_master(master);
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return 0;
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}
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static struct driver_d altera_spi_driver = {
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.name = "altera_spi",
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.probe = altera_spi_probe,
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};
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static int altera_spi_driver_init(void)
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{
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return register_driver(&altera_spi_driver);
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}
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device_initcall(altera_spi_driver_init);
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