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// SPDX-License-Identifier: GPL-2.0-only
/*
* 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>
*/
#include <linux/errno.h>
#include <linux/module.h>
#include <linux/platform_device.h>
#include <linux/spi/altera.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
static int altr_spi_writel(struct altera_spi *hw, unsigned int reg,
unsigned int val)
{
int ret;
ret = regmap_write(hw->regmap, hw->regoff + reg, val);
if (ret)
dev_err(hw->dev, "fail to write reg 0x%x val 0x%x: %d\n",
reg, val, ret);
return ret;
}
static int altr_spi_readl(struct altera_spi *hw, unsigned int reg,
unsigned int *val)
{
int ret;
ret = regmap_read(hw->regmap, hw->regoff + reg, val);
if (ret)
dev_err(hw->dev, "fail to read reg 0x%x: %d\n", reg, ret);
return ret;
}
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;
altr_spi_writel(hw, ALTERA_SPI_CONTROL, hw->imr);
altr_spi_writel(hw, ALTERA_SPI_SLAVE_SEL, 0);
} else {
altr_spi_writel(hw, ALTERA_SPI_SLAVE_SEL,
BIT(spi->chip_select));
hw->imr |= ALTERA_SPI_CONTROL_SSO_MSK;
altr_spi_writel(hw, ALTERA_SPI_CONTROL, hw->imr);
}
}
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;
case 4:
txd = (hw->tx[hw->count * 4]
| (hw->tx[hw->count * 4 + 1] << 8)
| (hw->tx[hw->count * 4 + 2] << 16)
| (hw->tx[hw->count * 4 + 3] << 24));
break;
}
}
altr_spi_writel(hw, ALTERA_SPI_TXDATA, txd);
}
static void altera_spi_rx_word(struct altera_spi *hw)
{
unsigned int rxd;
altr_spi_readl(hw, ALTERA_SPI_RXDATA, &rxd);
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;
case 4:
hw->rx[hw->count * 4] = rxd;
hw->rx[hw->count * 4 + 1] = rxd >> 8;
hw->rx[hw->count * 4 + 2] = rxd >> 16;
hw->rx[hw->count * 4 + 3] = rxd >> 24;
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);
u32 val;
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;
altr_spi_writel(hw, ALTERA_SPI_CONTROL, hw->imr);
/* send the first byte */
altera_spi_tx_word(hw);
return 1;
}
while (hw->count < hw->len) {
altera_spi_tx_word(hw);
for (;;) {
altr_spi_readl(hw, ALTERA_SPI_STATUS, &val);
if (val & ALTERA_SPI_STATUS_RRDY_MSK)
break;
cpu_relax();
}
altera_spi_rx_word(hw);
}
spi_finalize_current_transfer(master);
return 0;
}
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;
altr_spi_writel(hw, ALTERA_SPI_CONTROL, hw->imr);
spi_finalize_current_transfer(master);
}
return IRQ_HANDLED;
}
EXPORT_SYMBOL_GPL(altera_spi_irq);
void altera_spi_init_master(struct spi_master *master)
{
struct altera_spi *hw = spi_master_get_devdata(master);
u32 val;
master->transfer_one = altera_spi_txrx;
master->set_cs = altera_spi_set_cs;
/* program defaults into the registers */
hw->imr = 0; /* disable spi interrupts */
altr_spi_writel(hw, ALTERA_SPI_CONTROL, hw->imr);
altr_spi_writel(hw, ALTERA_SPI_STATUS, 0); /* clear status reg */
altr_spi_readl(hw, ALTERA_SPI_STATUS, &val);
if (val & ALTERA_SPI_STATUS_RRDY_MSK)
altr_spi_readl(hw, ALTERA_SPI_RXDATA, &val); /* flush rxdata */
}
EXPORT_SYMBOL_GPL(altera_spi_init_master);
MODULE_LICENSE("GPL");
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