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/*
* Copyright (C) 2011-12 Synopsys, Inc. (www.synopsys.com)
*
* 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/interrupt.h>
#include <linux/module.h>
#include <linux/of.h>
#include <linux/irqdomain.h>
#include <linux/irqchip.h>
#include <asm/irq.h>
/*
* Early Hardware specific Interrupt setup
* -Platform independent, needed for each CPU (not foldable into init_IRQ)
* -Called very early (start_kernel -> setup_arch -> setup_processor)
*
* what it does ?
* -Optionally, setup the High priority Interrupts as Level 2 IRQs
*/
void arc_init_IRQ(void)
{
int level_mask = 0;
/* setup any high priority Interrupts (Level2 in ARCompact jargon) */
level_mask |= IS_ENABLED(CONFIG_ARC_IRQ3_LV2) << 3;
level_mask |= IS_ENABLED(CONFIG_ARC_IRQ5_LV2) << 5;
level_mask |= IS_ENABLED(CONFIG_ARC_IRQ6_LV2) << 6;
/*
* Write to register, even if no LV2 IRQs configured to reset it
* in case bootloader had mucked with it
*/
write_aux_reg(AUX_IRQ_LEV, level_mask);
if (level_mask)
pr_info("Level-2 interrupts bitset %x\n", level_mask);
}
/*
* ARC700 core includes a simple on-chip intc supporting
* -per IRQ enable/disable
* -2 levels of interrupts (high/low)
* -all interrupts being level triggered
*
* To reduce platform code, we assume all IRQs directly hooked-up into intc.
* Platforms with external intc, hence cascaded IRQs, are free to over-ride
* below, per IRQ.
*/
static void arc_irq_mask(struct irq_data *data)
{
unsigned int ienb;
ienb = read_aux_reg(AUX_IENABLE);
ienb &= ~(1 << data->irq);
write_aux_reg(AUX_IENABLE, ienb);
}
static void arc_irq_unmask(struct irq_data *data)
{
unsigned int ienb;
ienb = read_aux_reg(AUX_IENABLE);
ienb |= (1 << data->irq);
write_aux_reg(AUX_IENABLE, ienb);
}
static struct irq_chip onchip_intc = {
.name = "ARC In-core Intc",
.irq_mask = arc_irq_mask,
.irq_unmask = arc_irq_unmask,
};
static int arc_intc_domain_map(struct irq_domain *d, unsigned int irq,
irq_hw_number_t hw)
{
/*
* XXX: the IPI IRQ needs to be handled like TIMER too. However ARC core
* code doesn't own it (like TIMER0). ISS IDU / ezchip define it
* in platform header which can't be included here as it goes
* against multi-platform image philisophy
*/
if (irq == TIMER0_IRQ)
irq_set_chip_and_handler(irq, &onchip_intc, handle_percpu_irq);
else
irq_set_chip_and_handler(irq, &onchip_intc, handle_level_irq);
return 0;
}
static const struct irq_domain_ops arc_intc_domain_ops = {
.xlate = irq_domain_xlate_onecell,
.map = arc_intc_domain_map,
};
static struct irq_domain *root_domain;
static int __init
init_onchip_IRQ(struct device_node *intc, struct device_node *parent)
{
if (parent)
panic("DeviceTree incore intc not a root irq controller\n");
root_domain = irq_domain_add_legacy(intc, NR_CPU_IRQS, 0, 0,
&arc_intc_domain_ops, NULL);
if (!root_domain)
panic("root irq domain not avail\n");
/* with this we don't need to export root_domain */
irq_set_default_host(root_domain);
return 0;
}
IRQCHIP_DECLARE(arc_intc, "snps,arc700-intc", init_onchip_IRQ);
/*
* arch_local_irq_enable - Enable interrupts.
*
* 1. Explicitly called to re-enable interrupts
* 2. Implicitly called from spin_unlock_irq, write_unlock_irq etc
* which maybe in hard ISR itself
*
* Semantics of this function change depending on where it is called from:
*
* -If called from hard-ISR, it must not invert interrupt priorities
* e.g. suppose TIMER is high priority (Level 2) IRQ
* Time hard-ISR, timer_interrupt( ) calls spin_unlock_irq several times.
* Here local_irq_enable( ) shd not re-enable lower priority interrupts
* -If called from soft-ISR, it must re-enable all interrupts
* soft ISR are low prioity jobs which can be very slow, thus all IRQs
* must be enabled while they run.
* Now hardware context wise we may still be in L2 ISR (not done rtie)
* still we must re-enable both L1 and L2 IRQs
* Another twist is prev scenario with flow being
* L1 ISR ==> interrupted by L2 ISR ==> L2 soft ISR
* here we must not re-enable Ll as prev Ll Interrupt's h/w context will get
* over-written (this is deficiency in ARC700 Interrupt mechanism)
*/
#ifdef CONFIG_ARC_COMPACT_IRQ_LEVELS /* Complex version for 2 IRQ levels */
void arch_local_irq_enable(void)
{
unsigned long flags = arch_local_save_flags();
/* Allow both L1 and L2 at the onset */
flags |= (STATUS_E1_MASK | STATUS_E2_MASK);
/* Called from hard ISR (between irq_enter and irq_exit) */
if (in_irq()) {
/* If in L2 ISR, don't re-enable any further IRQs as this can
* cause IRQ priorities to get upside down. e.g. it could allow
* L1 be taken while in L2 hard ISR which is wrong not only in
* theory, it can also cause the dreaded L1-L2-L1 scenario
*/
if (flags & STATUS_A2_MASK)
flags &= ~(STATUS_E1_MASK | STATUS_E2_MASK);
/* Even if in L1 ISR, allowe Higher prio L2 IRQs */
else if (flags & STATUS_A1_MASK)
flags &= ~(STATUS_E1_MASK);
}
/* called from soft IRQ, ideally we want to re-enable all levels */
else if (in_softirq()) {
/* However if this is case of L1 interrupted by L2,
* re-enabling both may cause whaco L1-L2-L1 scenario
* because ARC700 allows level 1 to interrupt an active L2 ISR
* Thus we disable both
* However some code, executing in soft ISR wants some IRQs
* to be enabled so we re-enable L2 only
*
* How do we determine L1 intr by L2
* -A2 is set (means in L2 ISR)
* -E1 is set in this ISR's pt_regs->status32 which is
* saved copy of status32_l2 when l2 ISR happened
*/
struct pt_regs *pt = get_irq_regs();
if ((flags & STATUS_A2_MASK) && pt &&
(pt->status32 & STATUS_A1_MASK)) {
/*flags &= ~(STATUS_E1_MASK | STATUS_E2_MASK); */
flags &= ~(STATUS_E1_MASK);
}
}
arch_local_irq_restore(flags);
}
#else /* ! CONFIG_ARC_COMPACT_IRQ_LEVELS */
/*
* Simpler version for only 1 level of interrupt
* Here we only Worry about Level 1 Bits
*/
void arch_local_irq_enable(void)
{
unsigned long flags;
/*
* ARC IDE Drivers tries to re-enable interrupts from hard-isr
* context which is simply wrong
*/
if (in_irq()) {
WARN_ONCE(1, "IRQ enabled from hard-isr");
return;
}
flags = arch_local_save_flags();
flags |= (STATUS_E1_MASK | STATUS_E2_MASK);
arch_local_irq_restore(flags);
}
#endif
EXPORT_SYMBOL(arch_local_irq_enable);
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