Re: [PATCH] irqchip: bcm2835: Add FIQ support

Noralf Trønnes
2015-06-18T13:33:25Z

Den 18.06.2015 04:26, skrev Stephen Warren:
> On 06/12/2015 11:26 AM, Noralf Trønnes wrote:
>> Add a duplicate irq range with an offset on the hwirq's so the
>> driver can detect that enable_fiq() is used.
>> Tested with downstream dwc_otg USB controller driver.
> This basically looks OK, but a few comments/thoughts:
>
> a) Should the Kconfig change be a separate patch since it's a separate
> subsystem?

I can separate it out.

> b) Doesn't the driver need to refuse some operation (handler
> registration, IRQ setup, IRQ enable, ...?) for more than 1 IRQ in the
> FIQ range, since the FIQ control register only allows routing 1 IRQ to FIQ.

claim_fiq() protects the FIQ. See d) answer below.

> c) The DT binding needs updating to describe the extra IRQs:
>
>> Documentation/devicetree/bindings/interrupt-controller/brcm,bcm28armctrl-ic.txt

Ok.

> d) I wonder how the FIQ handler actually gets routed to this controller
> and hooked to its handler etc. I assume there's a separate patch for
> that coming?

set_fiq_handler() sets the handler and enable_fiq() enables it:

if (claim_fiq(&fh))
ERROR;
set_fiq_handler(...)
set_fiq_regs(&regs);
enable_fiq(irq);
local_fiq_enable();

Downstream dwc_otg
------------------

FIQ handler:
https://github.com/raspberrypi/linux/blob/rpi-4.0.y/drivers/usb/host/dwc_otg/dwc_otg_fiq_stub.S

FIQ is set up in hcd_init_fiq():
https://github.com/raspberrypi/linux/blob/rpi-4.0.y/drivers/usb/host/dwc_otg/dwc_otg_hcd_linux.c

This patch is also necessary:
diff --git a/drivers/usb/host/dwc_otg/dwc_otg_driver.c
b/drivers/usb/host/dwc_otg/dwc_otg_driver.c
index 53307f0..95edadf 100644
--- a/drivers/usb/host/dwc_otg/dwc_otg_driver.c
+++ b/drivers/usb/host/dwc_otg/dwc_otg_driver.c
@@ -723,6 +723,7 @@ static int dwc_otg_driver_probe(

memset(dwc_otg_device, 0, sizeof(*dwc_otg_device));
dwc_otg_device->os_dep.reg_offset = 0xFFFFFFFF;
+ dwc_otg_device->os_dep.platformdev = _dev;

/*
* Map the DWC_otg Core memory into virtual address space.
diff --git a/drivers/usb/host/dwc_otg/dwc_otg_hcd_intr.c
b/drivers/usb/host/dwc_otg/dwc_otg_hcd_intr.c
index 8a31562..2961985 100644
--- a/drivers/usb/host/dwc_otg/dwc_otg_hcd_intr.c
+++ b/drivers/usb/host/dwc_otg/dwc_otg_hcd_intr.c
@@ -36,10 +36,8 @@
#include "dwc_otg_regs.h"

#include <linux/jiffies.h>
-#include <mach/hardware.h>
#include <asm/fiq.h>

-
extern bool microframe_schedule;

/** @file
diff --git a/drivers/usb/host/dwc_otg/dwc_otg_hcd_linux.c
b/drivers/usb/host/dwc_otg/dwc_otg_hcd_linux.c
index 6aad9c4..0440c66 100644
--- a/drivers/usb/host/dwc_otg/dwc_otg_hcd_linux.c
+++ b/drivers/usb/host/dwc_otg/dwc_otg_hcd_linux.c
@@ -445,7 +445,11 @@ static void hcd_init_fiq(void *cookie)
DWC_WARN("MPHI periph has NOT been enabled");
#endif
// Enable FIQ interrupt from USB peripheral
+#ifdef CONFIG_ARCH_BCM2835
+ enable_fiq(platform_get_irq(otg_dev->os_dep.platformdev, 1));
+#else
enable_fiq(INTERRUPT_VC_USB);
+#endif
local_fiq_enable();
}

DT node:
usb: usb@7e980000 {
compatible = "brcm,bcm2708-usb";
reg = <0x7e980000 0x10000>,
<0x7e006000 0x1000>;
interrupts = <2 0>,
<1 9>;
};