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|
/*
* MicroWire interface driver for OMAP
*
* Copyright 2003 MontaVista Software Inc. <source@mvista.com>
*
* Ported to 2.6 OMAP uwire interface.
* Copyright (C) 2004 Texas Instruments.
*
* Generalization patches by Juha Yrjola <juha.yrjola@nokia.com>
*
* Copyright (C) 2005 David Brownell (ported to 2.6 SPI interface)
* Copyright (C) 2006 Nokia
*
* Many updates by Imre Deak <imre.deak@nokia.com>
*
* This program is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License as published by the
* Free Software Foundation; either version 2 of the License, or (at your
* option) any later version.
*
* THIS SOFTWARE IS PROVIDED "AS IS" AND ANY EXPRESS OR IMPLIED
* WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
* MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
* USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
* ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/delay.h>
#include <linux/platform_device.h>
#include <linux/interrupt.h>
#include <linux/err.h>
#include <linux/clk.h>
#include <linux/slab.h>
#include <linux/device.h>
#include <linux/spi/spi.h>
#include <linux/spi/spi_bitbang.h>
#include <linux/module.h>
#include <linux/io.h>
#include <mach/hardware.h>
#include <asm/mach-types.h>
#include <mach/mux.h>
#include <mach/omap7xx.h> /* OMAP7XX_IO_CONF registers */
/* FIXME address is now a platform device resource,
* and irqs should show there too...
*/
#define UWIRE_BASE_PHYS 0xFFFB3000
/* uWire Registers: */
#define UWIRE_IO_SIZE 0x20
#define UWIRE_TDR 0x00
#define UWIRE_RDR 0x00
#define UWIRE_CSR 0x01
#define UWIRE_SR1 0x02
#define UWIRE_SR2 0x03
#define UWIRE_SR3 0x04
#define UWIRE_SR4 0x05
#define UWIRE_SR5 0x06
/* CSR bits */
#define RDRB (1 << 15)
#define CSRB (1 << 14)
#define START (1 << 13)
#define CS_CMD (1 << 12)
/* SR1 or SR2 bits */
#define UWIRE_READ_FALLING_EDGE 0x0001
#define UWIRE_READ_RISING_EDGE 0x0000
#define UWIRE_WRITE_FALLING_EDGE 0x0000
#define UWIRE_WRITE_RISING_EDGE 0x0002
#define UWIRE_CS_ACTIVE_LOW 0x0000
#define UWIRE_CS_ACTIVE_HIGH 0x0004
#define UWIRE_FREQ_DIV_2 0x0000
#define UWIRE_FREQ_DIV_4 0x0008
#define UWIRE_FREQ_DIV_8 0x0010
#define UWIRE_CHK_READY 0x0020
#define UWIRE_CLK_INVERTED 0x0040
struct uwire_spi {
struct spi_bitbang bitbang;
struct clk *ck;
};
struct uwire_state {
unsigned div1_idx;
};
/* REVISIT compile time constant for idx_shift? */
/*
* Or, put it in a structure which is used throughout the driver;
* that avoids having to issue two loads for each bit of static data.
*/
static unsigned int uwire_idx_shift;
static void __iomem *uwire_base;
static inline void uwire_write_reg(int idx, u16 val)
{
__raw_writew(val, uwire_base + (idx << uwire_idx_shift));
}
static inline u16 uwire_read_reg(int idx)
{
return __raw_readw(uwire_base + (idx << uwire_idx_shift));
}
static inline void omap_uwire_configure_mode(u8 cs, unsigned long flags)
{
u16 w, val = 0;
int shift, reg;
if (flags & UWIRE_CLK_INVERTED)
val ^= 0x03;
val = flags & 0x3f;
if (cs & 1)
shift = 6;
else
shift = 0;
if (cs <= 1)
reg = UWIRE_SR1;
else
reg = UWIRE_SR2;
w = uwire_read_reg(reg);
w &= ~(0x3f << shift);
w |= val << shift;
uwire_write_reg(reg, w);
}
static int wait_uwire_csr_flag(u16 mask, u16 val, int might_not_catch)
{
u16 w;
int c = 0;
unsigned long max_jiffies = jiffies + HZ;
for (;;) {
w = uwire_read_reg(UWIRE_CSR);
if ((w & mask) == val)
break;
if (time_after(jiffies, max_jiffies)) {
printk(KERN_ERR "%s: timeout. reg=%#06x "
"mask=%#06x val=%#06x\n",
__func__, w, mask, val);
return -1;
}
c++;
if (might_not_catch && c > 64)
break;
}
return 0;
}
static void uwire_set_clk1_div(int div1_idx)
{
u16 w;
w = uwire_read_reg(UWIRE_SR3);
w &= ~(0x03 << 1);
w |= div1_idx << 1;
uwire_write_reg(UWIRE_SR3, w);
}
static void uwire_chipselect(struct spi_device *spi, int value)
{
struct uwire_state *ust = spi->controller_state;
u16 w;
int old_cs;
BUG_ON(wait_uwire_csr_flag(CSRB, 0, 0));
w = uwire_read_reg(UWIRE_CSR);
old_cs = (w >> 10) & 0x03;
if (value == BITBANG_CS_INACTIVE || old_cs != spi->chip_select) {
/* Deselect this CS, or the previous CS */
w &= ~CS_CMD;
uwire_write_reg(UWIRE_CSR, w);
}
/* activate specfied chipselect */
if (value == BITBANG_CS_ACTIVE) {
uwire_set_clk1_div(ust->div1_idx);
/* invert clock? */
if (spi->mode & SPI_CPOL)
uwire_write_reg(UWIRE_SR4, 1);
else
uwire_write_reg(UWIRE_SR4, 0);
w = spi->chip_select << 10;
w |= CS_CMD;
uwire_write_reg(UWIRE_CSR, w);
}
}
static int uwire_txrx(struct spi_device *spi, struct spi_transfer *t)
{
unsigned len = t->len;
unsigned bits = t->bits_per_word;
unsigned bytes;
u16 val, w;
int status = 0;
if (!t->tx_buf && !t->rx_buf)
return 0;
w = spi->chip_select << 10;
w |= CS_CMD;
if (t->tx_buf) {
const u8 *buf = t->tx_buf;
/* NOTE: DMA could be used for TX transfers */
/* write one or two bytes at a time */
while (len >= 1) {
/* tx bit 15 is first sent; we byteswap multibyte words
* (msb-first) on the way out from memory.
*/
val = *buf++;
if (bits > 8) {
bytes = 2;
val |= *buf++ << 8;
} else
bytes = 1;
val <<= 16 - bits;
#ifdef VERBOSE
pr_debug("%s: write-%d =%04x\n",
dev_name(&spi->dev), bits, val);
#endif
if (wait_uwire_csr_flag(CSRB, 0, 0))
goto eio;
uwire_write_reg(UWIRE_TDR, val);
/* start write */
val = START | w | (bits << 5);
uwire_write_reg(UWIRE_CSR, val);
len -= bytes;
/* Wait till write actually starts.
* This is needed with MPU clock 60+ MHz.
* REVISIT: we may not have time to catch it...
*/
if (wait_uwire_csr_flag(CSRB, CSRB, 1))
goto eio;
status += bytes;
}
/* REVISIT: save this for later to get more i/o overlap */
if (wait_uwire_csr_flag(CSRB, 0, 0))
goto eio;
} else if (t->rx_buf) {
u8 *buf = t->rx_buf;
/* read one or two bytes at a time */
while (len) {
if (bits > 8) {
bytes = 2;
} else
bytes = 1;
/* start read */
val = START | w | (bits << 0);
uwire_write_reg(UWIRE_CSR, val);
len -= bytes;
/* Wait till read actually starts */
(void) wait_uwire_csr_flag(CSRB, CSRB, 1);
if (wait_uwire_csr_flag(RDRB | CSRB,
RDRB, 0))
goto eio;
/* rx bit 0 is last received; multibyte words will
* be properly byteswapped on the way to memory.
*/
val = uwire_read_reg(UWIRE_RDR);
val
|