On 01/12/2016 08:03 PM, Marc Zyngier wrote:

On 17/12/15 11:52, Tomasz Nowicki wrote:

quoted

On systems supporting GICv3 and above, in MADT GICC structures, the
field of GICR Base Address holds the 64-bit physical address of the
associated Redistributor if the GIC Redistributors are not in the
always-on power domain, so instead of init GICR regions via GIC
redistributor structure(s), init it with GICR base address in GICC
structures in that case.

Signed-off-by: Hanjun Guo <redacted>
Signed-off-by: Tomasz Nowicki <redacted>
---
  drivers/irqchip/irq-gic-v3.c | 98 ++++++++++++++++++++++++++++++++++++++++----
  1 file changed, 89 insertions(+), 9 deletions(-)

diff --git a/drivers/irqchip/irq-gic-v3.c b/drivers/irqchip/irq-gic-v3.c
index c4b929c..0528e82 100644
--- a/drivers/irqchip/irq-gic-v3.c
+++ b/drivers/irqchip/irq-gic-v3.c

@@ -39,6 +39,7 @@
  struct redist_region {
  	void __iomem		*redist_base;
  	phys_addr_t		phys_base;
+	bool			single_redist;
  };

  struct gic_chip_data {

@@ -435,6 +436,9 @@ static int gic_populate_rdist(void)
  				return 0;
  			}

+			if (gic_data.redist_regions[i].single_redist)
+				break;
+
  			if (gic_data.redist_stride) {
  				ptr += gic_data.redist_stride;
  			} else {

@@ -965,6 +969,7 @@ IRQCHIP_DECLARE(gic_v3, "arm,gic-v3", gic_of_init);
  #ifdef CONFIG_ACPI
  static struct redist_region *redist_regs __initdata;
  static u32 nr_redist_regions __initdata;
+static bool single_redist;

  static int __init
  gic_acpi_register_redist(phys_addr_t phys_base, u64 size)

@@ -979,7 +984,8 @@ gic_acpi_register_redist(phys_addr_t phys_base, u64 size)
  	}

  	redist_regs[count].phys_base = phys_base;
-	redist_regs[count++].redist_base = redist_base;
+	redist_regs[count].redist_base = redist_base;

nit: move the count++ out of the access in the previous patch, this will
make this series a bit easier to follow.

OK.

quoted

+	redist_regs[count++].single_redist = single_redist;

What is that single_redist for? Is that because you can't rely on
GICR_TYPER.Last?

Yes, there is no GICR_TYPER.Last bit for some redistributors,
as it's valid for redistributor regions.

quoted

  	return 0;
  }

@@ -993,6 +999,48 @@ gic_acpi_parse_madt_redist(struct acpi_subtable_header *header,
  	return gic_acpi_register_redist(redist->base_address, redist->length);
  }

+static int __init
+gic_acpi_parse_madt_gicc(struct acpi_subtable_header *header,
+			 const unsigned long end)
+{
+	struct acpi_madt_generic_interrupt *gicc;
+	void __iomem *redist_base;
+	u64 typer;
+	u32 size;
+
+	gicc = (struct acpi_madt_generic_interrupt *)header;
+	redist_base = ioremap(gicc->gicr_base_address, SZ_64K * 2);
+	if (!redist_base)
+		return -ENOMEM;
+
+	typer = readq_relaxed(redist_base + GICR_TYPER);
+	/* don't map reserved page as it's buggy to access it */
+	size = (typer & GICR_TYPER_VLPIS) ? SZ_64K * 3 : SZ_64K * 2;
+	iounmap(redist_base);

What a mess. If you discover a !VLPIS redistributor, why do you have to
unmap it to remap it again? Also, please map the whole region for the

I think I missed something here, I didn't know it's GICv3 or v4, I need
to check the GICR_TYPER first, then decide map 2 or 4 SZ_64K pages.

redistributor as we have on the DT side (4 64kB pages for VLPIS capable
redistributors).

Also, the spec says:

"On systems supporting GICv3 and above, this field holds the 64-bit
physical address of the associated Redistributor. If all of the GIC
Redistributors are in the always-on power domain, GICR structures should
be used to describe the Redistributors instead, and this field must be
set to 0."

which triggers two questions:
- Can you access always the GICR_TYPER register without waking the
redistributor up?

I missed this part, can you suggest how can we do that? accessing some
register before access to redistributor?

- How do you cope with situations where some redistributors are in the
always-on domain, and some are not?

I'm not sure if there is such hardware, if yes, do we need to fix
the spec first?

quoted

+	return gic_acpi_register_redist(gicc->gicr_base_address, size);
+}
+
+static int __init gic_acpi_collect_gicr_base(void)
+{
+	acpi_tbl_entry_handler redist_parser;
+	enum acpi_madt_type type;
+
+	if (single_redist) {
+		type = ACPI_MADT_TYPE_GENERIC_INTERRUPT;
+		redist_parser = gic_acpi_parse_madt_gicc;
+	} else {
+		type = ACPI_MADT_TYPE_GENERIC_REDISTRIBUTOR;
+		redist_parser = gic_acpi_parse_madt_redist;
+	}
+
+	/* Collect redistributor base addresses in GICR entries */
+	if (acpi_table_parse_madt(type, redist_parser, 0) > 0)
+		return 0;
+
+	pr_info("No valid GICR entries exist\n");
+	return -ENODEV;
+}
+
  static int __init gic_acpi_match_gicr(struct acpi_subtable_header *header,
  				  const unsigned long end)
  {

@@ -1000,6 +1048,42 @@ static int __init gic_acpi_match_gicr(struct acpi_subtable_header *header,
  	return 0;
  }

+static int __init gic_acpi_match_gicc(struct acpi_subtable_header *header,
+				      const unsigned long end)
+{
+	struct acpi_madt_generic_interrupt *gicc =
+				(struct acpi_madt_generic_interrupt *)header;
+
+	/*
+	 * If GICC is enabled and has valid gicr base address, then it means
+	 * GICR base is presented via GICC
+	 */
+	if ((gicc->flags & ACPI_MADT_ENABLED) && gicc->gicr_base_address)
+		return 0;
+
+	return -ENODEV;
+}
+
+static int __init gic_acpi_count_gicr_regions(void)
+{
+	int count;
+
+	/* Count how many redistributor regions we have */
+	count = acpi_table_parse_madt(ACPI_MADT_TYPE_GENERIC_REDISTRIBUTOR,
+				      gic_acpi_match_gicr, 0);
+	if (count > 0) {
+		single_redist = false;
+		return count;
+	}
+
+	count = acpi_table_parse_madt(ACPI_MADT_TYPE_GENERIC_INTERRUPT,
+				      gic_acpi_match_gicc, 0);
+	if (count > 0)
+		single_redist = true;
+
+	return count;
+}
+

Here, you seem to consider GICR and GICC tables to be mutually
exclusive. I don't think the spec says so.

Good question, I will ask Charles first about it.

Thanks
Hanjun