spi-sh-sci.c
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/*
* SH SCI SPI interface
*
* Copyright (c) 2008 Magnus Damm
*
* Based on S3C24XX GPIO based SPI driver, which is:
* Copyright (c) 2006 Ben Dooks
* Copyright (c) 2006 Simtec Electronics
*
* 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/delay.h>
#include <linux/spinlock.h>
#include <linux/platform_device.h>
#include <linux/spi/spi.h>
#include <linux/spi/spi_bitbang.h>
#include <linux/module.h>
#include <asm/spi.h>
#include <asm/io.h>
struct sh_sci_spi {
struct spi_bitbang bitbang;
void __iomem *membase;
unsigned char val;
struct sh_spi_info *info;
struct platform_device *dev;
};
#define SCSPTR(sp) (sp->membase + 0x1c)
#define PIN_SCK (1 << 2)
#define PIN_TXD (1 << 0)
#define PIN_RXD PIN_TXD
#define PIN_INIT ((1 << 1) | (1 << 3) | PIN_SCK | PIN_TXD)
static inline void setbits(struct sh_sci_spi *sp, int bits, int on)
{
/*
* We are the only user of SCSPTR so no locking is required.
* Reading bit 2 and 0 in SCSPTR gives pin state as input.
* Writing the same bits sets the output value.
* This makes regular read-modify-write difficult so we
* use sp->val to keep track of the latest register value.
*/
if (on)
sp->val |= bits;
else
sp->val &= ~bits;
iowrite8(sp->val, SCSPTR(sp));
}
static inline void setsck(struct spi_device *dev, int on)
{
setbits(spi_master_get_devdata(dev->master), PIN_SCK, on);
}
static inline void setmosi(struct spi_device *dev, int on)
{
setbits(spi_master_get_devdata(dev->master), PIN_TXD, on);
}
static inline u32 getmiso(struct spi_device *dev)
{
struct sh_sci_spi *sp = spi_master_get_devdata(dev->master);
return (ioread8(SCSPTR(sp)) & PIN_RXD) ? 1 : 0;
}
#define spidelay(x) ndelay(x)
#include "spi-bitbang-txrx.h"
static u32 sh_sci_spi_txrx_mode0(struct spi_device *spi,
unsigned nsecs, u32 word, u8 bits)
{
return bitbang_txrx_be_cpha0(spi, nsecs, 0, 0, word, bits);
}
static u32 sh_sci_spi_txrx_mode1(struct spi_device *spi,
unsigned nsecs, u32 word, u8 bits)
{
return bitbang_txrx_be_cpha1(spi, nsecs, 0, 0, word, bits);
}
static u32 sh_sci_spi_txrx_mode2(struct spi_device *spi,
unsigned nsecs, u32 word, u8 bits)
{
return bitbang_txrx_be_cpha0(spi, nsecs, 1, 0, word, bits);
}
static u32 sh_sci_spi_txrx_mode3(struct spi_device *spi,
unsigned nsecs, u32 word, u8 bits)
{
return bitbang_txrx_be_cpha1(spi, nsecs, 1, 0, word, bits);
}
static void sh_sci_spi_chipselect(struct spi_device *dev, int value)
{
struct sh_sci_spi *sp = spi_master_get_devdata(dev->master);
if (sp->info->chip_select)
(sp->info->chip_select)(sp->info, dev->chip_select, value);
}
static int sh_sci_spi_probe(struct platform_device *dev)
{
struct resource *r;
struct spi_master *master;
struct sh_sci_spi *sp;
int ret;
master = spi_alloc_master(&dev->dev, sizeof(struct sh_sci_spi));
if (master == NULL) {
dev_err(&dev->dev, "failed to allocate spi master\n");
ret = -ENOMEM;
goto err0;
}
sp = spi_master_get_devdata(master);
platform_set_drvdata(dev, sp);
sp->info = dev_get_platdata(&dev->dev);
if (!sp->info) {
dev_err(&dev->dev, "platform data is missing\n");
ret = -ENOENT;
goto err1;
}
/* setup spi bitbang adaptor */
sp->bitbang.master = master;
sp->bitbang.master->bus_num = sp->info->bus_num;
sp->bitbang.master->num_chipselect = sp->info->num_chipselect;
sp->bitbang.chipselect = sh_sci_spi_chipselect;
sp->bitbang.txrx_word[SPI_MODE_0] = sh_sci_spi_txrx_mode0;
sp->bitbang.txrx_word[SPI_MODE_1] = sh_sci_spi_txrx_mode1;
sp->bitbang.txrx_word[SPI_MODE_2] = sh_sci_spi_txrx_mode2;
sp->bitbang.txrx_word[SPI_MODE_3] = sh_sci_spi_txrx_mode3;
r = platform_get_resource(dev, IORESOURCE_MEM, 0);
if (r == NULL) {
ret = -ENOENT;
goto err1;
}
sp->membase = ioremap(r->start, resource_size(r));
if (!sp->membase) {
ret = -ENXIO;
goto err1;
}
sp->val = ioread8(SCSPTR(sp));
setbits(sp, PIN_INIT, 1);
ret = spi_bitbang_start(&sp->bitbang);
if (!ret)
return 0;
setbits(sp, PIN_INIT, 0);
iounmap(sp->membase);
err1:
spi_master_put(sp->bitbang.master);
err0:
return ret;
}
static int sh_sci_spi_remove(struct platform_device *dev)
{
struct sh_sci_spi *sp = platform_get_drvdata(dev);
spi_bitbang_stop(&sp->bitbang);
setbits(sp, PIN_INIT, 0);
iounmap(sp->membase);
spi_master_put(sp->bitbang.master);
return 0;
}
static struct platform_driver sh_sci_spi_drv = {
.probe = sh_sci_spi_probe,
.remove = sh_sci_spi_remove,
.driver = {
.name = "spi_sh_sci",
},
};
module_platform_driver(sh_sci_spi_drv);
MODULE_DESCRIPTION("SH SCI SPI Driver");
MODULE_AUTHOR("Magnus Damm <damm@opensource.se>");
MODULE_LICENSE("GPL");
MODULE_ALIAS("platform:spi_sh_sci");