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/*
* linux/arch/arm/mach-sa1100/ssp.c
*
* Copyright (C) 2003 Russell King.
*
* 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.
*
* Generic SSP driver. This provides the generic core for simple
* IO-based SSP applications.
*/
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/sched.h>
#include <linux/errno.h>
#include <linux/interrupt.h>
#include <linux/ioport.h>
#include <linux/init.h>
#include <asm/io.h>
#include <asm/irq.h>
#include <asm/hardware.h>
#include <asm/hardware/ssp.h>
#define TIMEOUT 100000
static irqreturn_t ssp_interrupt(int irq, void *dev_id, struct pt_regs *regs)
{
unsigned int status = Ser4SSSR;
if (status & SSSR_ROR) {
printk(KERN_WARNING "SSP: receiver overrun\n");
}
Ser4SSSR = SSSR_ROR;
return status ? IRQ_HANDLED : IRQ_NONE;
}
/**
* ssp_write_word - write a word to the SSP port
* @data: 16-bit, MSB justified data to write.
*
* Wait for a free entry in the SSP transmit FIFO, and write a data
* word to the SSP port. Wait for the SSP port to start sending
* the data.
*
* The caller is expected to perform the necessary locking.
*
* Returns:
* %-ETIMEDOUT timeout occurred
* 0 success
*/
int ssp_write_word(u16 data)
{
int timeout = TIMEOUT;
while (!(Ser4SSSR & SSSR_TNF)) {
if (!--timeout)
return -ETIMEDOUT;
cpu_relax();
}
Ser4SSDR = data;
timeout = TIMEOUT;
while (!(Ser4SSSR & SSSR_BSY)) {
if (!--timeout)
return -ETIMEDOUT;
cpu_relax();
}
return 0;
}
/**
* ssp_read_word - read a word from the SSP port
*
* Wait for a data word in the SSP receive FIFO, and return the
* received data. Data is LSB justified.
*
* Note: Currently, if data is not expected to be received, this
* function will wait for ever.
*
* The caller is expected to perform the necessary locking.
*
* Returns:
* %-ETIMEDOUT timeout occurred
* 16-bit data success
*/
int ssp_read_word(u16 *data)
{
int timeout = TIMEOUT;
while (!(Ser4SSSR & SSSR_RNE)) {
if (!--timeout)
return -ETIMEDOUT;
cpu_relax();
}
*data = (u16)Ser4SSDR;
return 0;
}
/**
* ssp_flush - flush the transmit and receive FIFOs
*
* Wait for the SSP to idle, and ensure that the receive FIFO
* is empty.
*
* The caller is expected to perform the necessary locking.
*
* Returns:
* %-ETIMEDOUT timeout occurred
* 0 success
*/
int ssp_flush(void)
{
int timeout = TIMEOUT * 2;
do {
while (Ser4SSSR & SSSR_RNE) {
if (!--timeout)
return -ETIMEDOUT;
(void) Ser4SSDR;
}
if (!--timeout)
return -ETIMEDOUT;
} while (Ser4SSSR & SSSR_BSY);
return 0;
}
/**
* ssp_enable - enable the SSP port
*
* Turn on the SSP port.
*/
void ssp_enable(void)
{
Ser4SSCR0 |= SSCR0_SSE;
}
/**
* ssp_disable - shut down the SSP port
*
* Turn off the SSP port, optionally powering it down.
*/
void ssp_disable(void)
{
Ser4SSCR0 &= ~SSCR0_SSE;
}
/**
* ssp_save_state - save the SSP configuration
* @ssp: pointer to structure to save SSP configuration
*
* Save the configured SSP state for suspend.
*/
void ssp_save_state(struct ssp_state *ssp)
{
ssp->cr0 = Ser4SSCR0;
ssp->cr1 = Ser4SSCR1;
Ser4SSCR0 &= ~SSCR0_SSE;
}
/**
* ssp_restore_state - restore a previously saved SSP configuration
* @ssp: pointer to configuration saved by ssp_save_state
*
* Restore the SSP configuration saved previously by ssp_save_state.
*/
void ssp_restore_state(struct ssp_state *ssp)
{
Ser4SSSR = SSSR_ROR;
Ser4SSCR0 = ssp->cr0 & ~SSCR0_SSE;
Ser4SSCR1 = ssp->cr1;
Ser4SSCR0 = ssp->cr0;
}
/**
* ssp_init - setup the SSP port
*
* initialise and claim resources for the SSP port.
*
* Returns:
* %-ENODEV if the SSP port is unavailable
* %-EBUSY if the resources are already in use
* %0 on success
*/
int ssp_init(void)
{
int ret;
if (!(PPAR & PPAR_SPR) && (Ser4MCCR0 & MCCR0_MCE))
return -ENODEV;
if (!request_mem_region(__PREG(Ser4SSCR0), 0x18, "SSP")) {
return -EBUSY;
}
Ser4SSSR = SSSR_ROR;
ret = request_irq(IRQ_Ser4SSP, ssp_interrupt, 0, "SSP", NULL);
if (ret)
goto out_region;
return 0;
out_region:
release_mem_region(__PREG(Ser4SSCR0), 0x18);
return ret;
}
/**
* ssp_exit - undo the effects of ssp_init
*
* release and free resources for the SSP port.
*/
void ssp_exit(void)
{
Ser4SSCR0 &= ~SSCR0_SSE;
free_irq(IRQ_Ser4SSP, NULL);
release_mem_region(__PREG(Ser4SSCR0), 0x18);
}
MODULE_AUTHOR("Russell King");
MODULE_DESCRIPTION("SA11x0 SSP PIO driver");
MODULE_LICENSE("GPL");
EXPORT_SYMBOL(ssp_write_word);
EXPORT_SYMBOL(ssp_read_word);
EXPORT_SYMBOL(ssp_flush);
EXPORT_SYMBOL(ssp_enable);
EXPORT_SYMBOL(ssp_disable);
EXPORT_SYMBOL(ssp_save_state);
EXPORT_SYMBOL(ssp_restore_state);
EXPORT_SYMBOL(ssp_init);
EXPORT_SYMBOL(ssp_exit);
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