Introduce support for registering an IPI IRQ domain suitable for use by
systems using the MIPS MT (multithreading) ASE within a single core.
This will allow for such systems to be supported generically, without
the current kludge of IPI code split between the MIPS arch & the malta
board support code.
Signed-off-by: Paul Burton <paul.burton@xxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: Jason Cooper <jason@xxxxxxxxxxxxxx>
Cc: Marc Zyngier <marc.zyngier@xxxxxxx>
Cc: Ralf Baechle <ralf@xxxxxxxxxxxxxx>
Cc: linux-mips@xxxxxxxxxxxxxx
---
drivers/irqchip/Kconfig | 2 +
drivers/irqchip/irq-mips-cpu.c | 125 ++++++++++++++++++++++++++++++++++++++---
2 files changed, 119 insertions(+), 8 deletions(-)
diff --git a/drivers/irqchip/Kconfig b/drivers/irqchip/Kconfig
index 125528f39e92..cfb33a365081 100644
--- a/drivers/irqchip/Kconfig
+++ b/drivers/irqchip/Kconfig
@@ -128,7 +128,9 @@ config IMGPDC_IRQ
config IRQ_MIPS_CPU
bool
select GENERIC_IRQ_CHIP
+ select GENERIC_IRQ_IPI if SYS_SUPPORTS_MULTITHREADING
select IRQ_DOMAIN
+ select IRQ_DOMAIN_HIERARCHY if GENERIC_IRQ_IPI
config CLPS711X_IRQCHIP
bool
diff --git a/drivers/irqchip/irq-mips-cpu.c b/drivers/irqchip/irq-mips-cpu.c
index 338de924b269..b247f3c743ac 100644
--- a/drivers/irqchip/irq-mips-cpu.c
+++ b/drivers/irqchip/irq-mips-cpu.c
@@ -17,15 +17,14 @@
/*
* Almost all MIPS CPUs define 8 interrupt sources. They are typically
* level triggered (i.e., cannot be cleared from CPU; must be cleared from
- * device). The first two are software interrupts which we don't really
- * use or support. The last one is usually the CPU timer interrupt if
- * counter register is present or, for CPUs with an external FPU, by
- * convention it's the FPU exception interrupt.
+ * device).
*
- * Don't even think about using this on SMP. You have been warned.
+ * The first two are software interrupts (i.e. not exposed as pins) which
+ * may be used for IPIs in multi-threaded single-core systems.
*
- * This file exports one global function:
- * void mips_cpu_irq_init(void);
+ * The last one is usually the CPU timer interrupt if the counter register
+ * is present, or for old CPUs with an external FPU by convention it's the
+ * FPU exception interrupt.
*/
#include <linux/init.h>
#include <linux/interrupt.h>
@@ -40,6 +39,7 @@
#include <asm/setup.h>
static struct irq_domain *irq_domain;
+static struct irq_domain *ipi_domain;
static inline void unmask_mips_irq(struct irq_data *d)
{
@@ -90,6 +90,29 @@ static void mips_mt_cpu_irq_ack(struct irq_data *d)
mask_mips_irq(d);
}
+#ifdef CONFIG_GENERIC_IRQ_IPI
+
+static void mips_mt_send_ipi(struct irq_data *d, unsigned int cpu)
+{
+ irq_hw_number_t hwirq = irqd_to_hwirq(d);
+ unsigned long flags;
+ int vpflags;
+
+ local_irq_save(flags);
+
+ /* We can only send IPIs to VPEs within the local core */
+ WARN_ON(cpu_data[cpu].core != current_cpu_data.core);
+
+ vpflags = dvpe();
+ settc(cpu_vpe_id(&cpu_data[cpu]));
+ write_vpe_c0_cause(read_vpe_c0_cause() | (C_SW0 << hwirq));
+ evpe(vpflags);
+
+ local_irq_restore(flags);
+}
+
+#endif /* CONFIG_GENERIC_IRQ_IPI */
+
static struct irq_chip mips_mt_cpu_irq_controller = {
.name = "MIPS",
.irq_startup = mips_mt_cpu_irq_startup,
@@ -100,6 +123,9 @@ static struct irq_chip mips_mt_cpu_irq_controller = {
.irq_eoi = unmask_mips_irq,
.irq_disable = mask_mips_irq,
.irq_enable = unmask_mips_irq,
+#ifdef CONFIG_GENERIC_IRQ_IPI
+ .ipi_send_single = mips_mt_send_ipi,
+#endif
};
asmlinkage void __weak plat_irq_dispatch(void)
@@ -116,7 +142,10 @@ asmlinkage void __weak plat_irq_dispatch(void)
pending >>= CAUSEB_IP;
while (pending) {
irq = fls(pending) - 1;
- virq = irq_linear_revmap(irq_domain, irq);
+ if (IS_ENABLED(CONFIG_GENERIC_IRQ_IPI) && irq < 2)
+ virq = irq_linear_revmap(ipi_domain, irq);
+ else
+ virq = irq_linear_revmap(irq_domain, irq);
do_IRQ(virq);
pending &= ~BIT(irq);
}
@@ -147,6 +176,79 @@ static const struct irq_domain_ops mips_cpu_intc_irq_domain_ops = {
.xlate = irq_domain_xlate_onecell,
};
+#ifdef CONFIG_GENERIC_IRQ_IPI
+
+struct cpu_ipi_domain_state {
+ DECLARE_BITMAP(allocated, 2);
+};
+
+static int mips_cpu_ipi_alloc(struct irq_domain *domain, unsigned int virq,
+ unsigned int nr_irqs, void *arg)
+{
+ struct cpu_ipi_domain_state *state = domain->host_data;
+ unsigned int i, hwirq;
+ int ret;
+
+ for (i = 0; i < nr_irqs; i++) {
+ hwirq = find_first_zero_bit(state->allocated, 2);
+ if (hwirq == 2)
+ return -EBUSY;
+ bitmap_set(state->allocated, hwirq, 1);
+
+ ret = irq_domain_set_hwirq_and_chip(domain, virq + i, hwirq,
+ &mips_mt_cpu_irq_controller,
+ NULL);
+ if (ret)
+ return ret;
+
+ ret = irq_set_irq_type(virq + i, IRQ_TYPE_LEVEL_HIGH);
+ if (ret)
+ return ret;
+ }
+
+ return 0;
+}
+
+static int mips_cpu_ipi_match(struct irq_domain *d, struct device_node *node,
+ enum irq_domain_bus_token bus_token)
+{
+ bool is_ipi;
+
+ switch (bus_token) {
+ case DOMAIN_BUS_IPI:
+ is_ipi = d->bus_token == bus_token;
+ return (!node || (to_of_node(d->fwnode) == node)) && is_ipi;
+ default:
+ return 0;
+ }
+}
+
+static const struct irq_domain_ops mips_cpu_ipi_chip_ops = {
+ .alloc = mips_cpu_ipi_alloc,
+ .match = mips_cpu_ipi_match,
+};
+
+static void mips_cpu_register_ipi_domain(struct device_node *of_node)
+{
+ struct cpu_ipi_domain_state *ipi_domain_state;
+
+ ipi_domain_state = kzalloc(sizeof(*ipi_domain_state), GFP_KERNEL);
+ ipi_domain = irq_domain_add_hierarchy(irq_domain,
+ IRQ_DOMAIN_FLAG_IPI_SINGLE,
+ 2, of_node,
+ &mips_cpu_ipi_chip_ops,
+ ipi_domain_state);
+ if (!ipi_domain)
+ panic("Failed to add MIPS CPU IPI domain");
+ ipi_domain->bus_token = DOMAIN_BUS_IPI;
+}
+
+#else /* !CONFIG_GENERIC_IRQ_IPI */
+
+static inline void mips_cpu_register_ipi_domain(struct device_node *of_node) {}
+
+#endif /* !CONFIG_GENERIC_IRQ_IPI */
+
static void __init __mips_cpu_irq_init(struct device_node *of_node)
{
/* Mask interrupts. */
@@ -158,6 +260,13 @@ static void __init __mips_cpu_irq_init(struct device_node *of_node)
NULL);
if (!irq_domain)
panic("Failed to add irqdomain for MIPS CPU");
+
+ /*
+ * Only proceed to register the software interrupt IPI implementation
+ * for CPUs which implement the MIPS MT (multi-threading) ASE.
+ */
+ if (cpu_has_mipsmt)
+ mips_cpu_register_ipi_domain(of_node);
}
void __init mips_cpu_irq_init(void)
--
2.12.1
