Re: [PATCH v6 20/31] irqchip/gic-v5: Add GICv5 PPI support

[Lorenzo Pieralisi <lpieralisi@kernel.org>]

On Wed, Jul 02, 2025 at 12:40:19PM +0100, Jonathan Cameron wrote:
> On Thu, 26 Jun 2025 12:26:11 +0200
> Lorenzo Pieralisi <lpieralisi@kernel.org> wrote:
> 
> > The GICv5 CPU interface implements support for PE-Private Peripheral
> > Interrupts (PPI), that are handled (enabled/prioritized/delivered)
> > entirely within the CPU interface hardware.
> 
> I can't remember where I got to last time so if I repeat stuff that
> you already responded to, feel free to just ignore me this time ;)
> 
> All superficial stuff. Feel free to completely ignore if you like.

We are at v6.16-rc4, series has been on the lists for 3 months, it has
been reviewed and we would like to get it into v6.17 if possible and
deemed reasonable, I am asking you folks please, what should I do ?

I can send a v7 with the changes requested below (no bug fixes there)
- it is fine by me - but I need to know please asap if we have a
plan to get this upstream this cycle.

Thanks,
Lorenzo

> > diff --git a/drivers/irqchip/irq-gic-v5.c b/drivers/irqchip/irq-gic-v5.c
> > new file mode 100644
> > index 000000000000..a08daa562d21
> > --- /dev/null
> > +++ b/drivers/irqchip/irq-gic-v5.c
> > @@ -0,0 +1,461 @@
> > +// SPDX-License-Identifier: GPL-2.0-only
> > +/*
> > + * Copyright (C) 2024-2025 ARM Limited, All Rights Reserved.
> > + */
> > +
> > +#define pr_fmt(fmt)	"GICv5: " fmt
> > +
> > +#include <linux/irqdomain.h>
> > +#include <linux/wordpart.h>
> > +
> > +#include <linux/irqchip.h>
> > +#include <linux/irqchip/arm-gic-v5.h>
> > +
> > +#include <asm/cpufeature.h>
> > +#include <asm/exception.h>
> > +
> > +static u8 pri_bits __ro_after_init = 5;
> > +
> > +#define GICV5_IRQ_PRI_MASK	0x1f
> > +#define GICV5_IRQ_PRI_MI	(GICV5_IRQ_PRI_MASK & GENMASK(4, 5 - pri_bits))
> > +
> > +#define PPI_NR	128
> > +
> > +static bool gicv5_cpuif_has_gcie(void)
> > +{
> > +	return this_cpu_has_cap(ARM64_HAS_GICV5_CPUIF);
> > +}
> > +
> > +struct gicv5_chip_data {
> > +	struct fwnode_handle	*fwnode;
> > +	struct irq_domain	*ppi_domain;
> > +};
> > +
> > +static struct gicv5_chip_data gicv5_global_data __read_mostly;
> 
> > +static void gicv5_hwirq_eoi(u32 hwirq_id, u8 hwirq_type)
> > +{
> > +	u64 cddi = hwirq_id | FIELD_PREP(GICV5_GIC_CDDI_TYPE_MASK, hwirq_type);
> 
> Slight preference for not needing to care where hwirq_id goes in CDDI or how big
> it is (other than when I checked the header defines).
>  
> 	u64 cddi = FIELD_PREP(GICV5_GIC_CDDI_ID_MASK, hwirq_id) |
>         	   FIELD_PREP(GICV5_GIC_CDDI_TYPE_MASK, hwirq_type);
> 
> 
> > +
> > +	gic_insn(cddi, CDDI);
> > +
> > +	gic_insn(0, CDEOI);
> > +}
> 
> > +static int gicv5_ppi_irq_get_irqchip_state(struct irq_data *d,
> > +					   enum irqchip_irq_state which,
> > +					   bool *state)
> > +{
> > +	u64 hwirq_id_bit = BIT_ULL(d->hwirq % 64);
> > +
> > +	switch (which) {
> > +	case IRQCHIP_STATE_PENDING:
> > +		*state = !!(read_ppi_sysreg_s(d->hwirq, PPI_PENDING) & hwirq_id_bit);
> 
> Technically don't need the !! but if you really like it I don't mind that much.
> 
> > +		return 0;
> > +	case IRQCHIP_STATE_ACTIVE:
> > +		*state = !!(read_ppi_sysreg_s(d->hwirq, PPI_ACTIVE) & hwirq_id_bit);
> > +		return 0;
> > +	default:
> > +		pr_debug("Unexpected PPI irqchip state\n");
> > +		return -EINVAL;
> > +	}
> > +}
> 
> 
> > +static int gicv5_irq_ppi_domain_translate(struct irq_domain *d,
> > +					  struct irq_fwspec *fwspec,
> > +					  irq_hw_number_t *hwirq,
> > +					  unsigned int *type)
> > +{
> > +	if (!is_of_node(fwspec->fwnode))
> > +		return -EINVAL;
> > +
> > +	if (fwspec->param_count < 3)
> 
> I don't care that much, but could relax this seeing as fwspec->param[2]
> isn't used anyway? Maybe a tiny comment on why it matters?
> 
> > +		return -EINVAL;
> > +
> > +	if (fwspec->param[0] != GICV5_HWIRQ_TYPE_PPI)
> > +		return -EINVAL;
> > +
> > +	*hwirq = fwspec->param[1];
> > +
> > +	/*
> > +	 * Handling mode is hardcoded for PPIs, set the type using
> > +	 * HW reported value.
> > +	 */
> > +	*type = gicv5_ppi_irq_is_level(*hwirq) ? IRQ_TYPE_LEVEL_LOW : IRQ_TYPE_EDGE_RISING;
> > +
> > +	return 0;
> 
> 
> > +static int __init gicv5_of_init(struct device_node *node, struct device_node *parent)
> > +{
> > +	int ret = gicv5_init_domains(of_fwnode_handle(node));
> > +	if (ret)
> > +		return ret;
> > +
> > +	gicv5_set_cpuif_pribits();
> > +
> > +	ret = gicv5_starting_cpu(smp_processor_id());
> > +	if (ret)
> > +		goto out_dom;
> > +
> > +	ret = set_handle_irq(gicv5_handle_irq);
> > +	if (ret)
> > +		goto out_int;
> > +
> > +	return 0;
> > +
> > +out_int:
> > +	gicv5_cpu_disable_interrupts();
> > +out_dom:
> > +	gicv5_free_domains();
> 
> Naming is always tricky but I'd not really expect gicv5_free_domains() as the
> pair of gicv5_init_domains() (which is doing creation rather than just initializing).
> 
> Ah well, names are never prefect and I don't really mind.
> 
> > +
> > +	return ret;
> > +}
> > +IRQCHIP_DECLARE(gic_v5, "arm,gic-v5", gicv5_of_init);
>