[PATCH v2 1/6] ARM: brcmstb: add infrastructure for ARM-based Broadcom STB SoCs

On Thursday 05 December 2013, Florian Fainelli wrote:

2013/12/3 Arnd Bergmann [off-list ref]:

quoted

quoted

+     addr = ioremap(BPHYSADDR(BCHP_IRQ0_IRQEN), sizeof(u32));
+     writel_relaxed(BCHP_IRQ0_IRQEN_uarta_irqen_MASK
+             | BCHP_IRQ0_IRQEN_uartb_irqen_MASK
+             | BCHP_IRQ0_IRQEN_uartc_irqen_MASK, addr);
+     iounmap(addr);

What does this part do? Isn't that something that should have been set
up by the boot loader?

The bootloader will typically use the UART in busy-looping mode and
not rely on interrupts, also the bootloader currently does not know
much about how many UARTs there are in the system and how they are
going to be used.

Well, it should at least know how many ports are wire up and be able
to set them up to a working state.

One possible way to solve this would be to write a very small irqchip
driver which only implements the "irq_enable" method to allow these
interrupts to be forwarded to the GIC. Somewhere in the Device Tree we
would have an interrupt-map property which describes the mapping
between the bits in BCHP_IRQ0_IRQEN and their corresponding
peripherals (UARTA, B, C).

Would that work?

I think that would work, but it's getting into the overdesign territory.
Can you clarify why this register exists in the first place and what
makes it necessary to set it up? Are there similar registers for all
other IRQs?

	Arnd