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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>
#include <linux/platform_device.h>
#include <linux/spi/spi.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 {
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_set_cs(struct spi_device *spi, bool is_high)
{
struct altera_spi *hw = altera_spi_to_hw(spi);
if (is_high) {
hw->imr &= ~ALTERA_SPI_CONTROL_SSO_MSK;
writel(hw->imr, hw->base + ALTERA_SPI_CONTROL);
writel(0, hw->base + ALTERA_SPI_SLAVE_SEL);
} else {
writel(BIT(spi->chip_select), hw->base + ALTERA_SPI_SLAVE_SEL);
hw->imr |= ALTERA_SPI_CONTROL_SSO_MSK;
writel(hw->imr, hw->base + ALTERA_SPI_CONTROL);
}
}
static void altera_spi_tx_word(struct altera_spi *hw)
{
unsigned int txd = 0;
if (hw->tx) {
switch (hw->bytes_per_word) {
case 1:
txd = hw->tx[hw->count];
break;
case 2:
txd = (hw->tx[hw->count * 2]
| (hw->tx[hw->count * 2 + 1] << 8));
break;
}
}
writel(txd, hw->base + ALTERA_SPI_TXDATA);
}
static void altera_spi_rx_word(struct altera_spi *hw)
{
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++;
}
static int altera_spi_txrx(struct spi_master *master,
struct spi_device *spi, struct spi_transfer *t)
{
struct altera_spi *hw = spi_master_get_devdata(master);
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 */
altera_spi_tx_word(hw);
} else {
while (hw->count < hw->len) {
altera_spi_tx_word(hw);
while (!(readl(hw->base + ALTERA_SPI_STATUS) &
ALTERA_SPI_STATUS_RRDY_MSK))
cpu_relax();
altera_spi_rx_word(hw);
}
spi_finalize_current_transfer(master);
}
return t->len;
}
static irqreturn_t altera_spi_irq(int irq, void *dev)
{
struct spi_master *master = dev;
struct altera_spi *hw = spi_master_get_devdata(master);
altera_spi_rx_word(hw);
if (hw->count < hw->len) {
altera_spi_tx_word(hw);
} else {
/* disable receive interrupt */
hw->imr &= ~ALTERA_SPI_CONTROL_IRRDY_MSK;
writel(hw->imr, hw->base + ALTERA_SPI_CONTROL);
spi_finalize_current_transfer(master);
}
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;
master->transfer_one = altera_spi_txrx;
master->set_cs = altera_spi_set_cs;
hw = spi_master_get_devdata(master);
/* 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;
}
/* 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) {
err = devm_request_irq(&pdev->dev, hw->irq, altera_spi_irq, 0,
pdev->name, master);
if (err)
goto exit;
}
err = devm_spi_register_master(&pdev->dev, master);
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;
}
#ifdef CONFIG_OF
static const struct of_device_id altera_spi_match[] = {
{ .compatible = "ALTR,spi-1.0", },
{ .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,
.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);
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