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openwrt-xburst/target/linux/ar71xx/files/drivers/spi/pb44_spi.c

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/*
* Atheros PB44 board SPI controller driver
*
* Copyright (C) 2009 Gabor Juhos <juhosg@openwrt.org>
*
* 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/kernel.h>
#include <linux/init.h>
#include <linux/delay.h>
#include <linux/spinlock.h>
#include <linux/workqueue.h>
#include <linux/platform_device.h>
#include <linux/io.h>
#include <linux/spi/spi.h>
#include <linux/spi/spi_bitbang.h>
#include <linux/bitops.h>
#include <linux/gpio.h>
#include <asm/mach-ar71xx/ar71xx.h>
#include <asm/mach-ar71xx/platform.h>
#define DRV_DESC "Atheros PB44 SPI Controller driver"
#define DRV_VERSION "0.1.0"
#define DRV_NAME "pb44-spi"
#undef PER_BIT_READ
struct ar71xx_spi {
struct spi_bitbang bitbang;
u32 ioc_base;
u32 reg_ctrl;
void __iomem *base;
struct platform_device *pdev;
};
static inline u32 pb44_spi_rr(struct ar71xx_spi *sp, unsigned reg)
{
return __raw_readl(sp->base + reg);
}
static inline void pb44_spi_wr(struct ar71xx_spi *sp, unsigned reg, u32 val)
{
__raw_writel(val, sp->base + reg);
}
static inline struct ar71xx_spi *spidev_to_sp(struct spi_device *spi)
{
return spi_master_get_devdata(spi->master);
}
static void pb44_spi_chipselect(struct spi_device *spi, int is_active)
{
struct ar71xx_spi *sp = spidev_to_sp(spi);
int cs_high = (spi->mode & SPI_CS_HIGH) ? is_active : !is_active;
if (is_active) {
/* set initial clock polarity */
if (spi->mode & SPI_CPOL)
sp->ioc_base |= SPI_IOC_CLK;
else
sp->ioc_base &= ~SPI_IOC_CLK;
pb44_spi_wr(sp, SPI_REG_IOC, sp->ioc_base);
}
if (spi->chip_select) {
unsigned long gpio = (unsigned long) spi->controller_data;
/* SPI is normally active-low */
gpio_set_value(gpio, cs_high);
} else {
if (cs_high)
sp->ioc_base |= SPI_IOC_CS0;
else
sp->ioc_base &= ~SPI_IOC_CS0;
pb44_spi_wr(sp, SPI_REG_IOC, sp->ioc_base);
}
}
static int pb44_spi_setup_cs(struct spi_device *spi)
{
struct ar71xx_spi *sp = spidev_to_sp(spi);
/* enable GPIO mode */
pb44_spi_wr(sp, SPI_REG_FS, SPI_FS_GPIO);
/* save CTRL register */
sp->reg_ctrl = pb44_spi_rr(sp, SPI_REG_CTRL);
sp->ioc_base = pb44_spi_rr(sp, SPI_REG_IOC);
/* TODO: setup speed? */
pb44_spi_wr(sp, SPI_REG_CTRL, 0x43);
if (spi->chip_select) {
unsigned long gpio = (unsigned long) spi->controller_data;
int status = 0;
status = gpio_request(gpio, dev_name(&spi->dev));
if (status)
return status;
status = gpio_direction_output(gpio, spi->mode & SPI_CS_HIGH);
if (status) {
gpio_free(gpio);
return status;
}
} else {
if (spi->mode & SPI_CS_HIGH)
sp->ioc_base |= SPI_IOC_CS0;
else
sp->ioc_base &= ~SPI_IOC_CS0;
pb44_spi_wr(sp, SPI_REG_IOC, sp->ioc_base);
}
return 0;
}
static void pb44_spi_cleanup_cs(struct spi_device *spi)
{
struct ar71xx_spi *sp = spidev_to_sp(spi);
if (spi->chip_select) {
unsigned long gpio = (unsigned long) spi->controller_data;
gpio_free(gpio);
}
/* restore CTRL register */
pb44_spi_wr(sp, SPI_REG_CTRL, sp->reg_ctrl);
/* disable GPIO mode */
pb44_spi_wr(sp, SPI_REG_FS, 0);
}
static int pb44_spi_setup(struct spi_device *spi)
{
int status = 0;
if (spi->bits_per_word > 32)
return -EINVAL;
if (!spi->controller_state) {
status = pb44_spi_setup_cs(spi);
if (status)
return status;
}
status = spi_bitbang_setup(spi);
if (status && !spi->controller_state)
pb44_spi_cleanup_cs(spi);
return status;
}
static void pb44_spi_cleanup(struct spi_device *spi)
{
pb44_spi_cleanup_cs(spi);
spi_bitbang_cleanup(spi);
}
static u32 pb44_spi_txrx_mode0(struct spi_device *spi, unsigned nsecs,
u32 word, u8 bits)
{
struct ar71xx_spi *sp = spidev_to_sp(spi);
u32 ioc = sp->ioc_base;
u32 ret;
/* clock starts at inactive polarity */
for (word <<= (32 - bits); likely(bits); bits--) {
u32 out;
if (word & (1 << 31))
out = ioc | SPI_IOC_DO;
else
out = ioc & ~SPI_IOC_DO;
/* setup MSB (to slave) on trailing edge */
pb44_spi_wr(sp, SPI_REG_IOC, out);
pb44_spi_wr(sp, SPI_REG_IOC, out | SPI_IOC_CLK);
word <<= 1;
#ifdef PER_BIT_READ
/* sample MSB (from slave) on leading edge */
ret = pb44_spi_rr(sp, SPI_REG_RDS);
pb44_spi_wr(sp, SPI_REG_IOC, out);
#endif
}
#ifndef PER_BIT_READ
ret = pb44_spi_rr(sp, SPI_REG_RDS);
#endif
return ret;
}
static int pb44_spi_probe(struct platform_device *pdev)
{
struct spi_master *master;
struct ar71xx_spi *sp;
struct ar71xx_spi_platform_data *pdata;
struct resource *r;
int ret;
master = spi_alloc_master(&pdev->dev, sizeof(*sp));
if (master == NULL) {
dev_err(&pdev->dev, "failed to allocate spi master\n");
return -ENOMEM;
}
sp = spi_master_get_devdata(master);
platform_set_drvdata(pdev, sp);
pdata = pdev->dev.platform_data;
master->setup = pb44_spi_setup;
master->cleanup = pb44_spi_cleanup;
if (pdata) {
master->bus_num = pdata->bus_num;
master->num_chipselect = pdata->num_chipselect;
} else {
master->bus_num = 0;
master->num_chipselect = 1;
}
sp->bitbang.master = spi_master_get(master);
sp->bitbang.chipselect = pb44_spi_chipselect;
sp->bitbang.txrx_word[SPI_MODE_0] = pb44_spi_txrx_mode0;
sp->bitbang.setup_transfer = spi_bitbang_setup_transfer;
sp->bitbang.flags = SPI_CS_HIGH;
r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
if (r == NULL) {
ret = -ENOENT;
goto err1;
}
sp->base = ioremap_nocache(r->start, r->end - r->start + 1);
if (!sp->base) {
ret = -ENXIO;
goto err1;
}
ret = spi_bitbang_start(&sp->bitbang);
if (!ret)
return 0;
iounmap(sp->base);
err1:
platform_set_drvdata(pdev, NULL);
spi_master_put(sp->bitbang.master);
return ret;
}
static int pb44_spi_remove(struct platform_device *pdev)
{
struct ar71xx_spi *sp = platform_get_drvdata(pdev);
spi_bitbang_stop(&sp->bitbang);
iounmap(sp->base);
platform_set_drvdata(pdev, NULL);
spi_master_put(sp->bitbang.master);
return 0;
}
static struct platform_driver pb44_spi_drv = {
.probe = pb44_spi_probe,
.remove = pb44_spi_remove,
.driver = {
.name = DRV_NAME,
.owner = THIS_MODULE,
},
};
static int __init pb44_spi_init(void)
{
return platform_driver_register(&pb44_spi_drv);
}
module_init(pb44_spi_init);
static void __exit pb44_spi_exit(void)
{
platform_driver_unregister(&pb44_spi_drv);
}
module_exit(pb44_spi_exit);
MODULE_ALIAS("platform:" DRV_NAME);
MODULE_DESCRIPTION(DRV_DESC);
MODULE_VERSION(DRV_VERSION);
MODULE_AUTHOR("Gabor Juhos <juhosg@openwrt.org>");
MODULE_LICENSE("GPL v2");