linux-kernel - [irqchip: irq/irqchip-next] irqchip/gic-v3: Detect LPI invalidation MMIO registers

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Date:   Wed, 04 May 2022 15:15:36 -0000
From:   "irqchip-bot for Marc Zyngier" <tip-bot2@...utronix.de>
To:     linux-kernel@...r.kernel.org
Cc:     Marc Zyngier <maz@...nel.org>, tglx@...utronix.de
Subject: [irqchip: irq/irqchip-next] irqchip/gic-v3: Detect LPI invalidation
 MMIO registers

The following commit has been merged into the irq/irqchip-next branch of irqchip:

Commit-ID:     a837ed362e7070d48b6064138d3b61eb75eb9fd9
Gitweb:        https://git.kernel.org/pub/scm/linux/kernel/git/maz/arm-platforms/a837ed362e7070d48b6064138d3b61eb75eb9fd9
Author:        Marc Zyngier <maz@...nel.org>
AuthorDate:    Tue, 05 Apr 2022 19:38:56 +01:00
Committer:     Marc Zyngier <maz@...nel.org>
CommitterDate: Wed, 04 May 2022 15:38:55 +01:00

irqchip/gic-v3: Detect LPI invalidation MMIO registers

Since GICv4.1, an implementation can offer the same MMIO-based
implementation as DirectLPI, only with an ITS. Given that this
can be hugely beneficial for workloads that are very LPI masking
heavy (although these workloads are admitedly a bit odd).

Interestingly, this is independent of RVPEI, which only *implies*
the functionnality.

So let's detect whether the implementation has GICR_CTLR.IR set,
and propagate this as DirectLPI to the ITS driver.

While we're at it, repaint the GICv3 banner so that we advertise
the various capabilities at boot time to be slightly less invasive.

Signed-off-by: Marc Zyngier <maz@...nel.org>
Link: https://lore.kernel.org/r/20220405183857.205960-3-maz@kernel.org
---
 drivers/irqchip/irq-gic-v3.c | 20 ++++++++++++++++----
 1 file changed, 16 insertions(+), 4 deletions(-)

diff --git a/drivers/irqchip/irq-gic-v3.c b/drivers/irqchip/irq-gic-v3.c
index b252d55..f98651e 100644
--- a/drivers/irqchip/irq-gic-v3.c
+++ b/drivers/irqchip/irq-gic-v3.c
@@ -919,6 +919,7 @@ static int __gic_update_rdist_properties(struct redist_region *region,
 					 void __iomem *ptr)
 {
 	u64 typer = gic_read_typer(ptr + GICR_TYPER);
+	u32 ctlr = readl_relaxed(ptr + GICR_CTLR);
 
 	/* Boot-time cleanip */
 	if ((typer & GICR_TYPER_VLPIS) && (typer & GICR_TYPER_RVPEID)) {
@@ -938,9 +939,18 @@ static int __gic_update_rdist_properties(struct redist_region *region,
 
 	gic_data.rdists.has_vlpis &= !!(typer & GICR_TYPER_VLPIS);
 
-	/* RVPEID implies some form of DirectLPI, no matter what the doc says... :-/ */
+	/*
+	 * TYPER.RVPEID implies some form of DirectLPI, no matter what the
+	 * doc says... :-/ And CTLR.IR implies another subset of DirectLPI
+	 * that the ITS driver can make use of for LPIs (and not VLPIs).
+	 *
+	 * These are 3 different ways to express the same thing, depending
+	 * on the revision of the architecture and its relaxations over
+	 * time. Just group them under the 'direct_lpi' banner.
+	 */
 	gic_data.rdists.has_rvpeid &= !!(typer & GICR_TYPER_RVPEID);
 	gic_data.rdists.has_direct_lpi &= (!!(typer & GICR_TYPER_DirectLPIS) |
+					   !!(ctlr & GICR_CTLR_IR) |
 					   gic_data.rdists.has_rvpeid);
 	gic_data.rdists.has_vpend_valid_dirty &= !!(typer & GICR_TYPER_DIRTY);
 
@@ -962,7 +972,11 @@ static void gic_update_rdist_properties(void)
 	gic_iterate_rdists(__gic_update_rdist_properties);
 	if (WARN_ON(gic_data.ppi_nr == UINT_MAX))
 		gic_data.ppi_nr = 0;
-	pr_info("%d PPIs implemented\n", gic_data.ppi_nr);
+	pr_info("GICv3 features: %d PPIs%s%s\n",
+		gic_data.ppi_nr,
+		gic_data.has_rss ? ", RSS" : "",
+		gic_data.rdists.has_direct_lpi ? ", DirectLPI" : "");
+
 	if (gic_data.rdists.has_vlpis)
 		pr_info("GICv4 features: %s%s%s\n",
 			gic_data.rdists.has_direct_lpi ? "DirectLPI " : "",
@@ -1803,8 +1817,6 @@ static int __init gic_init_bases(void __iomem *dist_base,
 	irq_domain_update_bus_token(gic_data.domain, DOMAIN_BUS_WIRED);
 
 	gic_data.has_rss = !!(typer & GICD_TYPER_RSS);
-	pr_info("Distributor has %sRange Selector support\n",
-		gic_data.has_rss ? "" : "no ");
 
 	if (typer & GICD_TYPER_MBIS) {
 		err = mbi_init(handle, gic_data.domain);