linux/arch/arm/mach-omap1/fpga.c

// SPDX-License-Identifier: GPL-2.0-only
/*
 * linux/arch/arm/mach-omap1/fpga.c
 *
 * Interrupt handler for OMAP-1510 Innovator FPGA
 *
 * Copyright (C) 2001 RidgeRun, Inc.
 * Author: Greg Lonnon <glonnon@ridgerun.com>
 *
 * Copyright (C) 2002 MontaVista Software, Inc.
 *
 * Separated FPGA interrupts from innovator1510.c and cleaned up for 2.6
 * Copyright (C) 2004 Nokia Corporation by Tony Lindrgen <tony@atomide.com>
 */

#include <linux/types.h>
#include <linux/gpio.h>
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/device.h>
#include <linux/errno.h>
#include <linux/io.h>

#include <asm/irq.h>
#include <asm/mach/irq.h>

#include "hardware.h"
#include "iomap.h"
#include "common.h"
#include "fpga.h"

static void fpga_mask_irq(struct irq_data *d)
{
	unsigned int irq = d->irq - OMAP_FPGA_IRQ_BASE;

	if (irq < 8)
		__raw_writeb((__raw_readb(OMAP1510_FPGA_IMR_LO)
			      & ~(1 << irq)), OMAP1510_FPGA_IMR_LO);
	else if (irq < 16)
		__raw_writeb((__raw_readb(OMAP1510_FPGA_IMR_HI)
			      & ~(1 << (irq - 8))), OMAP1510_FPGA_IMR_HI);
	else
		__raw_writeb((__raw_readb(INNOVATOR_FPGA_IMR2)
			      & ~(1 << (irq - 16))), INNOVATOR_FPGA_IMR2);
}


static inline u32 get_fpga_unmasked_irqs(void)
{
	return
		((__raw_readb(OMAP1510_FPGA_ISR_LO) &
		  __raw_readb(OMAP1510_FPGA_IMR_LO))) |
		((__raw_readb(OMAP1510_FPGA_ISR_HI) &
		  __raw_readb(OMAP1510_FPGA_IMR_HI)) << 8) |
		((__raw_readb(INNOVATOR_FPGA_ISR2) &
		  __raw_readb(INNOVATOR_FPGA_IMR2)) << 16);
}


static void fpga_ack_irq(struct irq_data *d)
{
	/* Don't need to explicitly ACK FPGA interrupts */
}

static void fpga_unmask_irq(struct irq_data *d)
{
	unsigned int irq = d->irq - OMAP_FPGA_IRQ_BASE;

	if (irq < 8)
		__raw_writeb((__raw_readb(OMAP1510_FPGA_IMR_LO) | (1 << irq)),
		     OMAP1510_FPGA_IMR_LO);
	else if (irq < 16)
		__raw_writeb((__raw_readb(OMAP1510_FPGA_IMR_HI)
			      | (1 << (irq - 8))), OMAP1510_FPGA_IMR_HI);
	else
		__raw_writeb((__raw_readb(INNOVATOR_FPGA_IMR2)
			      | (1 << (irq - 16))), INNOVATOR_FPGA_IMR2);
}

static void fpga_mask_ack_irq(struct irq_data *d)
{
	fpga_mask_irq(d);
	fpga_ack_irq(d);
}

static void innovator_fpga_IRQ_demux(struct irq_desc *desc)
{
	u32 stat;
	int fpga_irq;

	stat = get_fpga_unmasked_irqs();

	if (!stat)
		return;

	for (fpga_irq = OMAP_FPGA_IRQ_BASE;
	     (fpga_irq < OMAP_FPGA_IRQ_END) && stat;
	     fpga_irq++, stat >>= 1) {
		if (stat & 1) {
			generic_handle_irq(fpga_irq);
		}
	}
}

static struct irq_chip omap_fpga_irq_ack = {
	.name		= "FPGA-ack",
	.irq_ack	= fpga_mask_ack_irq,
	.irq_mask	= fpga_mask_irq,
	.irq_unmask	= fpga_unmask_irq,
};


static struct irq_chip omap_fpga_irq = {
	.name		= "FPGA",
	.irq_ack	= fpga_ack_irq,
	.irq_mask	= fpga_mask_irq,
	.irq_unmask	= fpga_unmask_irq,
};

/*
 * All of the FPGA interrupt request inputs except for the touchscreen are
 * edge-sensitive; the touchscreen is level-sensitive.  The edge-sensitive
 * interrupts are acknowledged as a side-effect of reading the interrupt
 * status register from the FPGA.  The edge-sensitive interrupt inputs
 * cause a problem with level interrupt requests, such as Ethernet.  The
 * problem occurs when a level interrupt request is asserted while its
 * interrupt input is masked in the FPGA, which results in a missed
 * interrupt.
 *
 * In an attempt to workaround the problem with missed interrupts, the
 * mask_ack routine for all of the FPGA interrupts has been changed from
 * fpga_mask_ack_irq() to fpga_ack_irq() so that the specific FPGA interrupt
 * being serviced is left unmasked.  We can do this because the FPGA cascade
 * interrupt is run with all interrupts masked.
 *
 * Limited testing indicates that this workaround appears to be effective
 * for the smc9194 Ethernet driver used on the Innovator.  It should work
 * on other FPGA interrupts as well, but any drivers that explicitly mask
 * interrupts at the interrupt controller via disable_irq/enable_irq
 * could pose a problem.
 */
void omap1510_fpga_init_irq(void)
{
	int i, res;

	__raw_writeb(0, OMAP1510_FPGA_IMR_LO);
	__raw_writeb(0, OMAP1510_FPGA_IMR_HI);
	__raw_writeb(0, INNOVATOR_FPGA_IMR2);

	for (i = OMAP_FPGA_IRQ_BASE; i < OMAP_FPGA_IRQ_END; i++) {

		if (i == OMAP1510_INT_FPGA_TS) {
			/*
			 * The touchscreen interrupt is level-sensitive, so
			 * we'll use the regular mask_ack routine for it.
			 */
			irq_set_chip(i, &omap_fpga_irq_ack);
		}
		else {
			/*
			 * All FPGA interrupts except the touchscreen are
			 * edge-sensitive, so we won't mask them.
			 */
			irq_set_chip(i, &omap_fpga_irq);
		}

		irq_set_handler(i, handle_edge_irq);
		irq_clear_status_flags(i, IRQ_NOREQUEST);
	}

	/*
	 * The FPGA interrupt line is connected to GPIO13. Claim this pin for
	 * the ARM.
	 *
	 * NOTE: For general GPIO/MPUIO access and interrupts, please see
	 * gpio.[ch]
	 */
	res = gpio_request(13, "FPGA irq");
	if (res) {
		pr_err("%s failed to get gpio\n", __func__);
		return;
	}
	gpio_direction_input(13);
	irq_set_irq_type(gpio_to_irq(13), IRQ_TYPE_EDGE_RISING);
	irq_set_chained_handler(OMAP1510_INT_FPGA, innovator_fpga_IRQ_demux);
}