Interrupts

SoC interrupts are bound at build time; there is no runtime handler registration and the vector table is in flash:

PBL_IRQ_CONNECT(I2C1, 5, pbl_i2c_sf32lb_irq_handler, &s_i2c1, 0);

PBL_IRQ_DIRECT(AON, 0, PBL_IRQ_ZERO_LATENCY) {
  /* handler body */
}

A line is named after its PBL_SOC_IRQN_<line> define in the SoC’s checked-in soc_irqs.h, which also gives its number: PBL_IRQN(I2C1) is PBL_SOC_IRQN_I2C1. Binding a line needs no vendor header. The SoC’s line count is CONFIG_NUM_IRQS and its priority bits CONFIG_NUM_IRQ_PRIO_BITS, both set in soc/*/Kconfig.defconfig.

PBL_IRQ_CONNECT() calls isr(arg) with whatever type isr takes (an empty arg calls isr()); PBL_IRQ_DIRECT() takes the handler body instead. Binding a line twice fails to link, and a line without a PBL_SOC_IRQN_<line> fails to compile.

The priority is in controller units (0 is the most urgent) and is programmed for every connected line by pbl_irq_init() at boot, so drivers only call pbl_irq_enable() and pbl_irq_disable(). A priority more urgent than PBL_IRQ_PRIO_MAX_SYSCALL is a build error unless the line is flagged PBL_IRQ_ZERO_LATENCY, in which case the ISR must not call the kernel. An enabled line nobody connected lands in arch_irq_spurious(), which asserts.