Re: [PATCHv3 3/6] irqchip/irq-pruss-intc: Add support for shared and invalid interrupts

From: Marc Zyngier
Date: Fri Jul 17 2020 - 07:02:45 EST

Next message: Gene Chen: "[PATCH v2 0/9] mfd: mt6360: Merge different sub-devices i2c read/write"
Previous message: Ulf Hansson: "Re: [RFC PATCH V3 01/21] mmc: add UHS-II related definitions in public headers"
Messages sorted by: [ date ] [ thread ] [ subject ] [ author ]

On Fri, 10 Jul 2020 21:59:17 +0100,
Suman Anna <s-anna@xxxxxx> wrote:

Hi Suman,

[...]

>
> Hi Marc,
>
> On 7/2/20 12:44 PM, Marc Zyngier wrote:
> > On 2020-07-02 15:17, Grzegorz Jaszczyk wrote:
> >> From: Suman Anna <s-anna@xxxxxx>
> >>
> >> The PRUSS INTC has a fixed number of output interrupt lines that are
> >> connected to a number of processors or other PRUSS instances or other
> >> devices (like DMA) on the SoC. The output interrupt lines 2 through 9
> >> are usually connected to the main Arm host processor and are referred
> >> to as host interrupts 0 through 7 from ARM/MPU perspective.
> >>
> >> All of these 8 host interrupts are not always exclusively connected
> >> to the Arm interrupt controller. Some SoCs have some interrupt lines
> >> not connected to the Arm interrupt controller at all, while a few others
> >> have the interrupt lines connected to multiple processors in which they
> >> need to be partitioned as per SoC integration needs. For example, AM437x
> >> and 66AK2G SoCs have 2 PRUSS instances each and have the host interrupt 5
> >> connected to the other PRUSS, while AM335x has host interrupt 0 shared
> >> between MPU and TSC_ADC and host interrupts 6 & 7 shared between MPU and
> >> a DMA controller.
> >>
> >> Add support to the PRUSS INTC driver to allow both these shared and
> >> invalid interrupts by not returning a failure if any of these interrupts
> >> are skipped from the corresponding INTC DT node.
> >
> > That's not exactly "adding support", is it? It really is "ignore these
> > interrupts because they are useless from the main CPU's perspective",
> > right?
>
> Correct. We can rephrase this to something like
> "Add logic to the PRUSS INTC driver to ignore.."
>
> >
> >>
> >> Signed-off-by: Suman Anna <s-anna@xxxxxx>
> >> Signed-off-by: Grzegorz Jaszczyk <grzegorz.jaszczyk@xxxxxxxxxx>
> >> ---
> >> v2->v3:
> >> - Extra checks for (intc->irqs[i]) in error/remove path was moved from
> >> Â "irqchip/irq-pruss-intc: Add a PRUSS irqchip driver for PRUSS
> >> Â interrupts" to this patch
> >> v1->v2:
> >> - https://patchwork.kernel.org/patch/11069757/
> >> ---
> >> Âdrivers/irqchip/irq-pruss-intc.c | 73
> >> +++++++++++++++++++++++++++++++++++++---
> >> Â1 file changed, 68 insertions(+), 5 deletions(-)
> >>
> >> diff --git a/drivers/irqchip/irq-pruss-intc.c
> >> b/drivers/irqchip/irq-pruss-intc.c
> >> index fb3dda3..49c936f 100644
> >> --- a/drivers/irqchip/irq-pruss-intc.c
> >> +++ b/drivers/irqchip/irq-pruss-intc.c
> >> @@ -65,11 +65,15 @@
> >> Â * @irqs: kernel irq numbers corresponding to PRUSS host interrupts
> >> Â * @base: base virtual address of INTC register space
> >> Â * @domain: irq domain for this interrupt controller
> >> + * @shared_intr: bit-map denoting if the MPU host interrupt is shared
> >
> > nit: bitmap
>
> ok
>
> >
> >> + * @invalid_intr: bit-map denoting if host interrupt is not
> >> connected to MPU
> >> Â */
> >> Âstruct pruss_intc {
> >> ÂÂÂÂ unsigned int irqs[MAX_NUM_HOST_IRQS];
> >> ÂÂÂÂ void __iomem *base;
> >> ÂÂÂÂ struct irq_domain *domain;
> >> +ÂÂÂ u16 shared_intr;
> >> +ÂÂÂ u16 invalid_intr;
> >
> > Please represent bitmaps as an unsigned long.
>
> ok. We have atmost 8 interrupts coming in, but agree on the change
> since we are using the BIT() macro below.
>
> >
> >> Â};
> >>
> >> Âstatic inline u32 pruss_intc_read_reg(struct pruss_intc *intc,
> >> unsigned int reg)
> >> @@ -222,7 +226,8 @@ static int pruss_intc_probe(struct
> >> platform_device *pdev)
> >> ÂÂÂÂÂÂÂÂ "host_intr4", "host_intr5", "host_intr6", "host_intr7", };
> >> ÂÂÂÂ struct device *dev = &pdev->dev;
> >> ÂÂÂÂ struct pruss_intc *intc;
> >> -ÂÂÂ int i, irq;
> >> +ÂÂÂ int i, irq, count;
> >> +ÂÂÂ u8 temp_intr[MAX_NUM_HOST_IRQS] = { 0 };
> >>
> >> ÂÂÂÂ intc = devm_kzalloc(dev, sizeof(*intc), GFP_KERNEL);
> >> ÂÂÂÂ if (!intc)
> >> @@ -235,6 +240,52 @@ static int pruss_intc_probe(struct
> >> platform_device *pdev)
> >> ÂÂÂÂÂÂÂÂ return PTR_ERR(intc->base);
> >> ÂÂÂÂ }
> >>
> >> +ÂÂÂ count = of_property_read_variable_u8_array(dev->of_node,
> >> +ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ "ti,irqs-reserved",
> >> +ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ temp_intr, 0,
> >> +ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ MAX_NUM_HOST_IRQS);
> >> +ÂÂÂ /*
> >> +ÂÂÂÂ * The irqs-reserved is used only for some SoC's therefore not
> >> having
> >> +ÂÂÂÂ * this property is still valid
> >> +ÂÂÂÂ */
> >> +ÂÂÂ if (count == -EINVAL)
> >> +ÂÂÂÂÂÂÂ count = 0;
> >> +ÂÂÂ if (count < 0)
> >> +ÂÂÂÂÂÂÂ return count;
> >> +
> >> +ÂÂÂ for (i = 0; i < count; i++) {
> >> +ÂÂÂÂÂÂÂ if (temp_intr[i] >= MAX_NUM_HOST_IRQS) {
> >> +ÂÂÂÂÂÂÂÂÂÂÂ dev_warn(dev, "ignoring invalid reserved irq %d\n",
> >> +ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ temp_intr[i]);
> >> +ÂÂÂÂÂÂÂÂÂÂÂ continue;
> >> +ÂÂÂÂÂÂÂ }
> >> +
> >> +ÂÂÂÂÂÂÂ intc->invalid_intr |= BIT(temp_intr[i]);
> >> +ÂÂÂ }
> >> +
> >> +ÂÂÂ count = of_property_read_variable_u8_array(dev->of_node,
> >> +ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ "ti,irqs-shared",
> >> +ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ temp_intr, 0,
> >> +ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ MAX_NUM_HOST_IRQS);
> >> +ÂÂÂ /*
> >> +ÂÂÂÂ * The irqs-shared is used only for some SoC's therefore not having
> >> +ÂÂÂÂ * this property is still valid
> >> +ÂÂÂÂ */
> >> +ÂÂÂ if (count == -EINVAL)
> >> +ÂÂÂÂÂÂÂ count = 0;
> >> +ÂÂÂ if (count < 0)
> >> +ÂÂÂÂÂÂÂ return count;
> >> +
> >> +ÂÂÂ for (i = 0; i < count; i++) {
> >> +ÂÂÂÂÂÂÂ if (temp_intr[i] >= MAX_NUM_HOST_IRQS) {
> >> +ÂÂÂÂÂÂÂÂÂÂÂ dev_warn(dev, "ignoring invalid shared irq %d\n",
> >> +ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ temp_intr[i]);
> >> +ÂÂÂÂÂÂÂÂÂÂÂ continue;
> >> +ÂÂÂÂÂÂÂ }
> >> +
> >> +ÂÂÂÂÂÂÂ intc->shared_intr |= BIT(temp_intr[i]);
> >> +ÂÂÂ }
> >> +
> >
> > You probably want to move this in a separate function, since you populate a
> > common structure.
> >
> >> ÂÂÂÂ pruss_intc_init(intc);
> >>
> >> ÂÂÂÂ /* always 64 events */
> >> @@ -244,8 +295,14 @@ static int pruss_intc_probe(struct
> >> platform_device *pdev)
> >> ÂÂÂÂÂÂÂÂ return -ENOMEM;
> >>
> >> ÂÂÂÂ for (i = 0; i < MAX_NUM_HOST_IRQS; i++) {
> >> +ÂÂÂÂÂÂÂ if (intc->invalid_intr & BIT(i))
> >> +ÂÂÂÂÂÂÂÂÂÂÂ continue;
> >> +
> >> ÂÂÂÂÂÂÂÂ irq = platform_get_irq_byname(pdev, irq_names[i]);
> >> ÂÂÂÂÂÂÂÂ if (irq <= 0) {
> >> +ÂÂÂÂÂÂÂÂÂÂÂ if (intc->shared_intr & BIT(i))
> >> +ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ continue;
> >
> > I don't really understand why you are treating these "shared" interrupts
> > differently from the invalid ones. In all cases, they shouldn't be used.
>
> The behavior is the same in how we handle it, but the difference is
> that an "invalid" one is never even connected to the ARM interrupt
> controller, while the "shared" one is a choice. So, unless this
> interrupt is being used/handled by a different processor/entity, you
> would not see this skipped from the dts node.

And I'm saying that all that matters is that you are discarding these
interrupts. Whether they are flagged invalid or shared, they are not
available to Linux. So the difference in handling is pointless and
only makes it harder to understand what you are doing.

Thanks,

M.

--
Without deviation from the norm, progress is not possible.

Next message: Gene Chen: "[PATCH v2 0/9] mfd: mt6360: Merge different sub-devices i2c read/write"
Previous message: Ulf Hansson: "Re: [RFC PATCH V3 01/21] mmc: add UHS-II related definitions in public headers"
Messages sorted by: [ date ] [ thread ] [ subject ] [ author ]