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/*
* Altera SPI driver
*
* Copyright (C) 2008 Thomas Chou <thomas@wytron.com.tw>
*
* Based on spi_s3c24xx.c, which is:
* Copyright (c) 2006 Ben Dooks
* Copyright (c) 2006 Simtec Electronics
* Ben Dooks <ben@simtec.co.uk>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*/
#include <linux/interrupt.h>
#include <linux/errno.h>
#include <linux/module.h>
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#include <linux/platform_device.h>
#include <linux/spi/spi.h>
#include <linux/spi/spi_bitbang.h>
#include <linux/io.h>
#include <linux/of.h>
#define DRV_NAME "spi_altera"
#define ALTERA_SPI_RXDATA 0
#define ALTERA_SPI_TXDATA 4
#define ALTERA_SPI_STATUS 8
#define ALTERA_SPI_CONTROL 12
#define ALTERA_SPI_SLAVE_SEL 20
#define ALTERA_SPI_STATUS_ROE_MSK 0x8
#define ALTERA_SPI_STATUS_TOE_MSK 0x10
#define ALTERA_SPI_STATUS_TMT_MSK 0x20
#define ALTERA_SPI_STATUS_TRDY_MSK 0x40
#define ALTERA_SPI_STATUS_RRDY_MSK 0x80
#define ALTERA_SPI_STATUS_E_MSK 0x100
#define ALTERA_SPI_CONTROL_IROE_MSK 0x8
#define ALTERA_SPI_CONTROL_ITOE_MSK 0x10
#define ALTERA_SPI_CONTROL_ITRDY_MSK 0x40
#define ALTERA_SPI_CONTROL_IRRDY_MSK 0x80
#define ALTERA_SPI_CONTROL_IE_MSK 0x100
#define ALTERA_SPI_CONTROL_SSO_MSK 0x400
struct altera_spi {
/* bitbang has to be first */
struct spi_bitbang bitbang;
struct completion done;
void __iomem *base;
int irq;
int len;
int count;
int bytes_per_word;
unsigned long imr;
/* data buffers */
const unsigned char *tx;
unsigned char *rx;
};
static inline struct altera_spi *altera_spi_to_hw(struct spi_device *sdev)
{
return spi_master_get_devdata(sdev->master);
}
static void altera_spi_chipsel(struct spi_device *spi, int value)
{
struct altera_spi *hw = altera_spi_to_hw(spi);
if (spi->mode & SPI_CS_HIGH) {
switch (value) {
case BITBANG_CS_INACTIVE:
writel(1 << spi->chip_select,
hw->base + ALTERA_SPI_SLAVE_SEL);
hw->imr |= ALTERA_SPI_CONTROL_SSO_MSK;
writel(hw->imr, hw->base + ALTERA_SPI_CONTROL);
break;
case BITBANG_CS_ACTIVE:
hw->imr &= ~ALTERA_SPI_CONTROL_SSO_MSK;
writel(hw->imr, hw->base + ALTERA_SPI_CONTROL);
writel(0, hw->base + ALTERA_SPI_SLAVE_SEL);
break;
}
} else {
switch (value) {
case BITBANG_CS_INACTIVE:
hw->imr &= ~ALTERA_SPI_CONTROL_SSO_MSK;
writel(hw->imr, hw->base + ALTERA_SPI_CONTROL);
break;
case BITBANG_CS_ACTIVE:
writel(1 << spi->chip_select,
hw->base + ALTERA_SPI_SLAVE_SEL);
hw->imr |= ALTERA_SPI_CONTROL_SSO_MSK;
writel(hw->imr, hw->base + ALTERA_SPI_CONTROL);
break;
}
}
}
static inline unsigned int hw_txbyte(struct altera_spi *hw, int count)
{
if (hw->tx) {
switch (hw->bytes_per_word) {
case 1:
return hw->tx[count];
case 2:
return (hw->tx[count * 2]
| (hw->tx[count * 2 + 1] << 8));
}
}
return 0;
}
static int altera_spi_txrx(struct spi_device *spi, struct spi_transfer *t)
{
struct altera_spi *hw = altera_spi_to_hw(spi);
hw->tx = t->tx_buf;
hw->rx = t->rx_buf;
hw->count = 0;
hw->bytes_per_word = DIV_ROUND_UP(t->bits_per_word, 8);
hw->len = t->len / hw->bytes_per_word;
if (hw->irq >= 0) {
/* enable receive interrupt */
hw->imr |= ALTERA_SPI_CONTROL_IRRDY_MSK;
writel(hw->imr, hw->base + ALTERA_SPI_CONTROL);
/* send the first byte */
writel(hw_txbyte(hw, 0), hw->base + ALTERA_SPI_TXDATA);
wait_for_completion(&hw->done);
/* disable receive interrupt */
hw->imr &= ~ALTERA_SPI_CONTROL_IRRDY_MSK;
writel(hw->imr, hw->base + ALTERA_SPI_CONTROL);
} else {
while (hw->count < hw->len) {
writel(hw_txbyte(hw, hw->count),
hw->base + ALTERA_SPI_TXDATA);
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while (!(readl(hw->base + ALTERA_SPI_STATUS) &
ALTERA_SPI_STATUS_RRDY_MSK))
cpu_relax();
rxd = readl(hw->base + ALTERA_SPI_RXDATA);
if (hw->rx) {
switch (hw->bytes_per_word) {
case 1:
hw->rx[hw->count] = rxd;
break;
case 2:
hw->rx[hw->count * 2] = rxd;
hw->rx[hw->count * 2 + 1] = rxd >> 8;
break;
}
}
hw->count++;
}
}
return hw->count * hw->bytes_per_word;
}
static irqreturn_t altera_spi_irq(int irq, void *dev)
{
struct altera_spi *hw = dev;
unsigned int rxd;
rxd = readl(hw->base + ALTERA_SPI_RXDATA);
if (hw->rx) {
switch (hw->bytes_per_word) {
case 1:
hw->rx[hw->count] = rxd;
break;
case 2:
hw->rx[hw->count * 2] = rxd;
hw->rx[hw->count * 2 + 1] = rxd >> 8;
break;
}
}
hw->count++;
if (hw->count < hw->len)
writel(hw_txbyte(hw, hw->count), hw->base + ALTERA_SPI_TXDATA);
else
complete(&hw->done);
return IRQ_HANDLED;
}
static int altera_spi_probe(struct platform_device *pdev)
{
struct altera_spi *hw;
struct spi_master *master;
struct resource *res;
int err = -ENODEV;
master = spi_alloc_master(&pdev->dev, sizeof(struct altera_spi));
if (!master)
return err;
/* setup the master state. */
master->bus_num = pdev->id;
master->num_chipselect = 16;
master->mode_bits = SPI_CS_HIGH;
master->bits_per_word_mask = SPI_BPW_RANGE_MASK(1, 16);
master->dev.of_node = pdev->dev.of_node;
hw = spi_master_get_devdata(master);
platform_set_drvdata(pdev, hw);
/* setup the state for the bitbang driver */
hw->bitbang.master = master;
hw->bitbang.chipselect = altera_spi_chipsel;
hw->bitbang.txrx_bufs = altera_spi_txrx;
/* find and map our resources */
res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
hw->base = devm_ioremap_resource(&pdev->dev, res);
if (IS_ERR(hw->base)) {
err = PTR_ERR(hw->base);
goto exit;
}
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/* program defaults into the registers */
hw->imr = 0; /* disable spi interrupts */
writel(hw->imr, hw->base + ALTERA_SPI_CONTROL);
writel(0, hw->base + ALTERA_SPI_STATUS); /* clear status reg */
if (readl(hw->base + ALTERA_SPI_STATUS) & ALTERA_SPI_STATUS_RRDY_MSK)
readl(hw->base + ALTERA_SPI_RXDATA); /* flush rxdata */
/* irq is optional */
hw->irq = platform_get_irq(pdev, 0);
if (hw->irq >= 0) {
init_completion(&hw->done);
err = devm_request_irq(&pdev->dev, hw->irq, altera_spi_irq, 0,
pdev->name, hw);
if (err)
goto exit;
}
/* register our spi controller */
err = spi_bitbang_start(&hw->bitbang);
if (err)
goto exit;
dev_info(&pdev->dev, "base %p, irq %d\n", hw->base, hw->irq);
return 0;
exit:
spi_master_put(master);
return err;
}
static int altera_spi_remove(struct platform_device *dev)
{
struct altera_spi *hw = platform_get_drvdata(dev);
struct spi_master *master = hw->bitbang.master;
spi_bitbang_stop(&hw->bitbang);
spi_master_put(master);
return 0;
}
#ifdef CONFIG_OF
static const struct of_device_id altera_spi_match[] = {
{ .compatible = "ALTR,spi-1.0", },
{},
};
MODULE_DEVICE_TABLE(of, altera_spi_match);
#endif /* CONFIG_OF */
static struct platform_driver altera_spi_driver = {
.probe = altera_spi_probe,
.driver = {
.name = DRV_NAME,
.owner = THIS_MODULE,
.pm = NULL,
.of_match_table = of_match_ptr(altera_spi_match),
module_platform_driver(altera_spi_driver);
MODULE_DESCRIPTION("Altera SPI driver");
MODULE_AUTHOR("Thomas Chou <thomas@wytron.com.tw>");
MODULE_LICENSE("GPL");
MODULE_ALIAS("platform:" DRV_NAME);