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/*
* Copyright 2002 Momentum Computer
* Author: mdharm@momenco.com
*
* arch/mips/momentum/ocelot_c/uart-irq.c
* Interrupt routines for UARTs. Interrupt numbers are assigned from
* 80 to 81 (2 interrupt sources).
*
* 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.
*/
#include <linux/module.h>
#include <linux/interrupt.h>
#include <linux/irq.h>
#include <linux/kernel.h>
#include <asm/ptrace.h>
#include <linux/sched.h>
#include <linux/kernel_stat.h>
#include <asm/io.h>
#include <asm/irq.h>
#include "ocelot_c_fpga.h"
static inline int ls1bit8(unsigned int x)
{
int b = 7, s;
s = 4; if (((unsigned char)(x << 4)) == 0) s = 0; b -= s; x <<= s;
s = 2; if (((unsigned char)(x << 2)) == 0) s = 0; b -= s; x <<= s;
s = 1; if (((unsigned char)(x << 1)) == 0) s = 0; b -= s;
return b;
}
/* mask off an interrupt -- 0 is enable, 1 is disable */
static inline void mask_uart_irq(unsigned int irq)
{
uint8_t value;
value = OCELOT_FPGA_READ(UART_INTMASK);
value |= 1 << (irq - 74);
OCELOT_FPGA_WRITE(value, UART_INTMASK);
/* read the value back to assure that it's really been written */
value = OCELOT_FPGA_READ(UART_INTMASK);
}
/* unmask an interrupt -- 0 is enable, 1 is disable */
static inline void unmask_uart_irq(unsigned int irq)
{
uint8_t value;
value = OCELOT_FPGA_READ(UART_INTMASK);
value &= ~(1 << (irq - 74));
OCELOT_FPGA_WRITE(value, UART_INTMASK);
/* read the value back to assure that it's really been written */
value = OCELOT_FPGA_READ(UART_INTMASK);
}
/*
* Enables the IRQ in the FPGA
*/
static void enable_uart_irq(unsigned int irq)
{
unmask_uart_irq(irq);
}
/*
* Initialize the IRQ in the FPGA
*/
static unsigned int startup_uart_irq(unsigned int irq)
{
unmask_uart_irq(irq);
return 0;
}
/*
* Disables the IRQ in the FPGA
*/
static void disable_uart_irq(unsigned int irq)
{
mask_uart_irq(irq);
}
/*
* Masks and ACKs an IRQ
*/
static void mask_and_ack_uart_irq(unsigned int irq)
{
mask_uart_irq(irq);
}
/*
* End IRQ processing
*/
static void end_uart_irq(unsigned int irq)
{
if (!(irq_desc[irq].status & (IRQ_DISABLED|IRQ_INPROGRESS)))
unmask_uart_irq(irq);
}
/*
* Interrupt handler for interrupts coming from the FPGA chip.
*/
void ll_uart_irq(struct pt_regs *regs)
{
unsigned int irq_src, irq_mask;
/* read the interrupt status registers */
irq_src = OCELOT_FPGA_READ(UART_INTSTAT);
irq_mask = OCELOT_FPGA_READ(UART_INTMASK);
/* mask for just the interrupts we want */
irq_src &= ~irq_mask;
do_IRQ(ls1bit8(irq_src) + 74, regs);
}
#define shutdown_uart_irq disable_uart_irq
struct irq_chip uart_irq_type = {
.typename = "UART/FPGA",
.startup = startup_uart_irq,
.shutdown = shutdown_uart_irq,
.enable = enable_uart_irq,
.disable = disable_uart_irq,
.ack = mask_and_ack_uart_irq,
.end = end_uart_irq,
};
void uart_irq_init(void)
{
/* Reset irq handlers pointers to NULL */
irq_desc[80].status = IRQ_DISABLED;
irq_desc[80].action = 0;
irq_desc[80].depth = 2;
irq_desc[80].chip = &uart_irq_type;
irq_desc[81].status = IRQ_DISABLED;
irq_desc[81].action = 0;
irq_desc[81].depth = 2;
irq_desc[81].chip = &uart_irq_type;
}
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