linux-kernel - [RFC PATCH] irqchip/gic-v3: Claim iomem resources

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Date:   Tue, 12 Apr 2022 16:28:15 +0100
From:   Robin Murphy <robin.murphy@....com>
To:     maz@...nel.org, tglx@...utronix.de
Cc:     linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: [RFC PATCH] irqchip/gic-v3: Claim iomem resources

As a simple quality-of-life tweak, claim our MMIO regions when mapping
them, such that the GIC shows up in /proc/iomem. No effort is spent on
trying to release them, since frankly if the GIC fails to probe then
it's never getting a second try anyway.

Signed-off-by: Robin Murphy <robin.murphy@....com>

---

I briefly looked at doing the same for GICv2, but quickly decided that
GICv2 isn't interesting enough to be worth the (greater) bother...

Lightly tested with ACPI.
---
 drivers/irqchip/irq-gic-v3.c | 15 +++++++++------
 1 file changed, 9 insertions(+), 6 deletions(-)

diff --git a/drivers/irqchip/irq-gic-v3.c b/drivers/irqchip/irq-gic-v3.c
index b252d5534547..9815b692a47a 100644
--- a/drivers/irqchip/irq-gic-v3.c
+++ b/drivers/irqchip/irq-gic-v3.c
@@ -1980,10 +1980,10 @@ static int __init gic_of_init(struct device_node *node, struct device_node *pare
 	u32 nr_redist_regions;
 	int err, i;
 
-	dist_base = of_iomap(node, 0);
-	if (!dist_base) {
+	dist_base = of_io_request_and_map(node, 0, "GICD");
+	if (IS_ERR(dist_base)) {
 		pr_err("%pOF: unable to map gic dist registers\n", node);
-		return -ENXIO;
+		return PTR_ERR(dist_base);
 	}
 
 	err = gic_validate_dist_version(dist_base);
@@ -2007,8 +2007,8 @@ static int __init gic_of_init(struct device_node *node, struct device_node *pare
 		int ret;
 
 		ret = of_address_to_resource(node, 1 + i, &res);
-		rdist_regs[i].redist_base = of_iomap(node, 1 + i);
-		if (ret || !rdist_regs[i].redist_base) {
+		rdist_regs[i].redist_base = of_io_request_and_map(node, 1 + i, "GICR");
+		if (ret || IS_ERR(rdist_regs[i].redist_base)) {
 			pr_err("%pOF: couldn't map region %d\n", node, i);
 			err = -ENODEV;
 			goto out_unmap_rdist;
@@ -2034,7 +2034,7 @@ static int __init gic_of_init(struct device_node *node, struct device_node *pare
 
 out_unmap_rdist:
 	for (i = 0; i < nr_redist_regions; i++)
-		if (rdist_regs[i].redist_base)
+		if (rdist_regs[i].redist_base && !IS_ERR(rdist_regs[i].redist_base))
 			iounmap(rdist_regs[i].redist_base);
 	kfree(rdist_regs);
 out_unmap_dist:
@@ -2081,6 +2081,7 @@ gic_acpi_parse_madt_redist(union acpi_subtable_headers *header,
 		pr_err("Couldn't map GICR region @%llx\n", redist->base_address);
 		return -ENOMEM;
 	}
+	request_mem_region(redist->base_address, redist->length, "GICR");
 
 	gic_acpi_register_redist(redist->base_address, redist_base);
 	return 0;
@@ -2103,6 +2104,7 @@ gic_acpi_parse_madt_gicc(union acpi_subtable_headers *header,
 	redist_base = ioremap(gicc->gicr_base_address, size);
 	if (!redist_base)
 		return -ENOMEM;
+	request_mem_region(gicc->gicr_base_address, size, "GICR");
 
 	gic_acpi_register_redist(gicc->gicr_base_address, redist_base);
 	return 0;
@@ -2304,6 +2306,7 @@ gic_acpi_init(union acpi_subtable_headers *header, const unsigned long end)
 		pr_err("Unable to map GICD registers\n");
 		return -ENOMEM;
 	}
+	request_mem_region(dist->base_address, ACPI_GICV3_DIST_MEM_SIZE, "GICD");
 
 	err = gic_validate_dist_version(acpi_data.dist_base);
 	if (err) {
-- 
2.28.0.dirty