[PATCH 10/11] irqchip/bcm2836: Configure mailbox interrupts as standard interrupts

Marc Zyngier
2020-05-19T16:33:30Z

In order to switch the bcm2836 driver to privide standard interrupts
for IPIs, it first needs to stop lying about the way things work.

The mailbox interrupt is actually a multiplexer, with enough
bits to store 32 pending interrupts per CPU. So let's turn it
into a chained irqchip.

Once this is done, we can instanciate the corresponding IPIs,
and pass them to the architecture code.

Signed-off-by: Marc Zyngier <maz@kernel.org>
---
drivers/irqchip/irq-bcm2836.c | 151 ++++++++++++++++++++++++++++------
1 file changed, 125 insertions(+), 26 deletions(-)

diff --git a/drivers/irqchip/irq-bcm2836.c b/drivers/irqchip/irq-bcm2836.c
index 2038693f074c..85df6ddad9be 100644
--- a/drivers/irqchip/irq-bcm2836.c
+++ b/drivers/irqchip/irq-bcm2836.c
@@ -10,6 +10,7 @@
#include <linux/of_irq.h>
#include <linux/irqchip.h>
#include <linux/irqdomain.h>
+#include <linux/irqchip/chained_irq.h>
#include <linux/irqchip/irq-bcm2836.h>

#include <asm/exception.h>
@@ -89,12 +90,24 @@ static struct irq_chip bcm2836_arm_irqchip_gpu = {
.irq_unmask = bcm2836_arm_irqchip_unmask_gpu_irq,
};

+static void bcm2836_arm_irqchip_dummy_op(struct irq_data *d)
+{
+}
+
+static struct irq_chip bcm2836_arm_irqchip_dummy = {
+ .name = "bcm2836-dummy",
+ .irq_eoi = bcm2836_arm_irqchip_dummy_op,
+};
+
static int bcm2836_map(struct irq_domain *d, unsigned int irq,
irq_hw_number_t hw)
{
struct irq_chip *chip;

switch (hw) {
+ case LOCAL_IRQ_MAILBOX0:
+ chip = &bcm2836_arm_irqchip_dummy;
+ break;
case LOCAL_IRQ_CNTPSIRQ:
case LOCAL_IRQ_CNTPNSIRQ:
case LOCAL_IRQ_CNTHPIRQ:
@@ -127,17 +140,7 @@ __exception_irq_entry bcm2836_arm_irqchip_handle_irq(struct pt_regs *regs)
u32 stat;

stat = readl_relaxed(intc.base + LOCAL_IRQ_PENDING0 + 4 * cpu);
- if (stat & BIT(LOCAL_IRQ_MAILBOX0)) {
-#ifdef CONFIG_SMP
- void __iomem *mailbox0 = (intc.base +
- LOCAL_MAILBOX0_CLR0 + 16 * cpu);
- u32 mbox_val = readl(mailbox0);
- u32 ipi = ffs(mbox_val) - 1;
-
- writel(1 << ipi, mailbox0);
- handle_IPI(ipi, regs);
-#endif
- } else if (stat) {
+ if (stat) {
u32 hwirq = ffs(stat) - 1;

handle_domain_irq(intc.domain, hwirq, regs);
@@ -145,8 +148,35 @@ __exception_irq_entry bcm2836_arm_irqchip_handle_irq(struct pt_regs *regs)
}

#ifdef CONFIG_SMP
-static void bcm2836_arm_irqchip_send_ipi(const struct cpumask *mask,
- unsigned int ipi)
+static struct irq_domain *ipi_domain;
+
+static void bcm2836_arm_irqchip_handle_ipi(struct irq_desc *desc)
+{
+ struct irq_chip *chip = irq_desc_get_chip(desc);
+ int cpu = smp_processor_id();
+ u32 mbox_val;
+
+ chained_irq_enter(chip, desc);
+
+ mbox_val = readl_relaxed(intc.base + LOCAL_MAILBOX0_CLR0 + 16 * cpu);
+ if (mbox_val) {
+ int hwirq = ffs(mbox_val) - 1;
+ generic_handle_irq(irq_find_mapping(ipi_domain, hwirq));
+ }
+
+ chained_irq_exit(chip, desc);
+}
+
+static void bcm2836_arm_irqchip_ipi_eoi(struct irq_data *d)
+{
+ int cpu = smp_processor_id();
+
+ writel_relaxed(BIT(d->hwirq),
+ intc.base + LOCAL_MAILBOX0_CLR0 + 16 * cpu);
+}
+
+static void bcm2836_arm_irqchip_ipi_send_mask(struct irq_data *d,
+ const struct cpumask *mask)
{
int cpu;
void __iomem *mailbox0_base = intc.base + LOCAL_MAILBOX0_SET0;
@@ -157,11 +187,45 @@ static void bcm2836_arm_irqchip_send_ipi(const struct cpumask *mask,
*/
smp_wmb();

- for_each_cpu(cpu, mask) {
- writel(1 << ipi, mailbox0_base + 16 * cpu);
+ for_each_cpu(cpu, mask)
+ writel_relaxed(BIT(d->hwirq), mailbox0_base + 16 * cpu);
+}
+
+static struct irq_chip bcm2836_arm_irqchip_ipi = {
+ .name = "IPI",
+ .irq_eoi = bcm2836_arm_irqchip_ipi_eoi,
+ .ipi_send_mask = bcm2836_arm_irqchip_ipi_send_mask,
+};
+
+static int bcm2836_arm_irqchip_ipi_alloc(struct irq_domain *d,
+ unsigned int virq,
+ unsigned int nr_irqs, void *args)
+{
+ int i;
+
+ for (i = 0; i < nr_irqs; i++) {
+ irq_set_percpu_devid(virq + i);
+ irq_domain_set_info(d, virq + i, i, &bcm2836_arm_irqchip_ipi,
+ d->host_data,
+ handle_percpu_devid_fasteoi_ipi,
+ NULL, NULL);
}
+
+ return 0;
}

+static void bcm2836_arm_irqchip_ipi_free(struct irq_domain *d,
+ unsigned int virq,
+ unsigned int nr_irqs)
+{
+ /* Not freeing IPIs */
+}
+
+static const struct irq_domain_ops ipi_domain_ops = {
+ .alloc = bcm2836_arm_irqchip_ipi_alloc,
+ .free = bcm2836_arm_irqchip_ipi_free,
+};
+
static int bcm2836_cpu_starting(unsigned int cpu)
{
bcm2836_arm_irqchip_unmask_per_cpu_irq(LOCAL_MAILBOX_INT_CONTROL0, 0,
@@ -175,25 +239,58 @@ static int bcm2836_cpu_dying(unsigned int cpu)
cpu);
return 0;
}
-#endif

-static const struct irq_domain_ops bcm2836_arm_irqchip_intc_ops = {
- .xlate = irq_domain_xlate_onetwocell,
- .map = bcm2836_map,
-};
+#define BITS_PER_MBOX 32

-static void
-bcm2836_arm_irqchip_smp_init(void)
+static void bcm2836_arm_irqchip_smp_init(void)
{
-#ifdef CONFIG_SMP
+ struct irq_fwspec ipi_fwspec = {
+ .fwnode = intc.domain->fwnode,
+ .param_count = 1,
+ .param = {
+ [0] = LOCAL_IRQ_MAILBOX0,
+ },
+ };
+ int base_ipi, mux_irq;
+
+ mux_irq = irq_create_fwspec_mapping(&ipi_fwspec);
+ if (WARN_ON(mux_irq <= 0))
+ return;
+
+ ipi_domain = irq_domain_create_linear(intc.domain->fwnode,
+ BITS_PER_MBOX, &ipi_domain_ops,
+ NULL);
+ if (WARN_ON(!ipi_domain))
+ return;
+
+ ipi_domain->flags |= IRQ_DOMAIN_FLAG_IPI_SINGLE;
+ irq_domain_update_bus_token(ipi_domain, DOMAIN_BUS_IPI);
+
+ base_ipi = __irq_domain_alloc_irqs(ipi_domain, -1, BITS_PER_MBOX,
+ NUMA_NO_NODE, NULL,
+ false, NULL);
+
+ if (WARN_ON(!base_ipi))
+ return;
+
+ set_smp_ipi_range(base_ipi, BITS_PER_MBOX);
+
+ irq_set_chained_handler_and_data(mux_irq,
+ bcm2836_arm_irqchip_handle_ipi, NULL);
+
/* Unmask IPIs to the boot CPU. */
cpuhp_setup_state(CPUHP_AP_IRQ_BCM2836_STARTING,
"irqchip/bcm2836:starting", bcm2836_cpu_starting,
bcm2836_cpu_dying);
-
- set_smp_cross_call(bcm2836_arm_irqchip_send_ipi);
-#endif
}
+#else
+#define bcm2836_arm_irqchip_smp_init() do { } while(0)
+#endif
+
+static const struct irq_domain_ops bcm2836_arm_irqchip_intc_ops = {
+ .xlate = irq_domain_xlate_onetwocell,
+ .map = bcm2836_map,
+};

/*
* The LOCAL_IRQ_CNT* timer firings are based off of the external
@@ -232,6 +329,8 @@ static int __init bcm2836_arm_irqchip_l1_intc_of_init(struct device_node *node,
if (!intc.domain)
panic("%pOF: unable to create IRQ domain\n", node);

+ irq_domain_update_bus_token(intc.domain, DOMAIN_BUS_WIRED);
+
bcm2836_arm_irqchip_smp_init();

set_handle_irq(bcm2836_arm_irqchip_handle_irq);
--
2.26.2