[Arm-dev] [PATCH v1 16/87] irqchip, gicv3: Add HW revision detection and configuration

[Vadim Lomovtsev]

From: Robert Richter <rrichter at cavium.com>

Some GIC revisions require an individual configuration to esp. add
workarounds for HW bugs. This patch implements generic code to parse
the hw revision provided by an IIDR register value and runs specific
code if hw matches. There are functions that read the IIDR registers
for GICV3 and ITS (GICD_IIDR/GITS_IIDR) and then go through a list of
init functions to be called for specific versions.

The patch is needed to implement workarounds for HW errata in Cavium's
ThunderX GICV3.

Signed-off-by: Robert Richter <rrichter at cavium.com>
Signed-off-by: Vadim Lomovtsev <Vadim.Lomovtsev at caviumnetworks.com>
---
 drivers/irqchip/irq-gic-common.c | 11 +++++++++++
 drivers/irqchip/irq-gic-common.h |  9 +++++++++
 drivers/irqchip/irq-gic-v3-its.c | 15 +++++++++++++++
 drivers/irqchip/irq-gic-v3.c     | 14 ++++++++++++++
 4 files changed, 49 insertions(+)

diff --git a/drivers/irqchip/irq-gic-common.c b/drivers/irqchip/irq-gic-common.c
index 9448e39..a55a609 100644
--- a/drivers/irqchip/irq-gic-common.c
+++ b/drivers/irqchip/irq-gic-common.c
@@ -21,6 +21,17 @@
 
 #include "irq-gic-common.h"
 
+void gic_check_capabilities(u32 iidr, const struct gic_capabilities *cap,
+			void *data)
+{
+	for (; cap->desc; cap++) {
+		if ((iidr & cap->mask) != cap->id)
+			continue;
+		cap->init(data);
+		pr_info("%s\n", cap->desc);
+	}
+}
+
 int gic_configure_irq(unsigned int irq, unsigned int type,
 		       void __iomem *base, void (*sync_access)(void))
 {
diff --git a/drivers/irqchip/irq-gic-common.h b/drivers/irqchip/irq-gic-common.h
index 35a9884..90d55b9 100644
--- a/drivers/irqchip/irq-gic-common.h
+++ b/drivers/irqchip/irq-gic-common.h
@@ -20,10 +20,19 @@
 #include <linux/of.h>
 #include <linux/irqdomain.h>
 
+struct gic_capabilities {
+	const char *desc;
+	void (*init)(void *data);
+	u32 id;
+	u32 mask;
+};
+
 int gic_configure_irq(unsigned int irq, unsigned int type,
                        void __iomem *base, void (*sync_access)(void));
 void gic_dist_config(void __iomem *base, int gic_irqs,
 		     void (*sync_access)(void));
 void gic_cpu_config(void __iomem *base, void (*sync_access)(void));
+void gic_check_capabilities(u32 iidr, const struct gic_capabilities *cap,
+			void *data);
 
 #endif /* _IRQ_GIC_COMMON_H */
diff --git a/drivers/irqchip/irq-gic-v3-its.c b/drivers/irqchip/irq-gic-v3-its.c
index 3542c75..47a9595 100644
--- a/drivers/irqchip/irq-gic-v3-its.c
+++ b/drivers/irqchip/irq-gic-v3-its.c
@@ -36,6 +36,7 @@
 #include <asm/cputype.h>
 #include <asm/exception.h>
 
+#include "irq-gic-common.h"
 #include "irqchip.h"
 
 #define ITS_FLAGS_CMDQ_NEEDS_FLUSHING		(1 << 0)
@@ -1432,6 +1433,18 @@ static int its_force_quiescent(void __iomem *base)
 	}
 }
 
+static const struct gic_capabilities its_errata[] = {
+	{
+	}
+};
+
+static void its_check_capabilities(struct its_node *its)
+{
+	u32 iidr = readl_relaxed(its->base + GITS_IIDR);
+
+	gic_check_capabilities(iidr, its_errata, its);
+}
+
 static int its_probe(struct device_node *node, struct irq_domain *parent)
 {
 	struct resource res;
@@ -1490,6 +1503,8 @@ static int its_probe(struct device_node *node, struct irq_domain *parent)
 	}
 	its->cmd_write = its->cmd_base;
 
+	its_check_capabilities(its);
+
 	err = its_alloc_tables(its);
 	if (err)
 		goto out_free_cmd;
diff --git a/drivers/irqchip/irq-gic-v3.c b/drivers/irqchip/irq-gic-v3.c
index 0019fed..7857943 100644
--- a/drivers/irqchip/irq-gic-v3.c
+++ b/drivers/irqchip/irq-gic-v3.c
@@ -771,6 +771,18 @@ static const struct irq_domain_ops gic_irq_domain_ops = {
 	.free = gic_irq_domain_free,
 };
 
+static const struct gic_capabilities gicv3_errata[] = {
+	{
+	}
+};
+
+static void gicv3_check_capabilities(void)
+{
+	u32 iidr = readl_relaxed(gic_data.dist_base + GICD_IIDR);
+
+	gic_check_capabilities(iidr, gicv3_errata, NULL);
+}
+
 static int __init gic_of_init(struct device_node *node, struct device_node *parent)
 {
 	void __iomem *dist_base;
@@ -830,6 +842,8 @@ static int __init gic_of_init(struct device_node *node, struct device_node *pare
 	gic_data.nr_redist_regions = nr_redist_regions;
 	gic_data.redist_stride = redist_stride;
 
+	gicv3_check_capabilities();
+
 	/*
 	 * Find out how many interrupts are supported.
 	 * The GIC only supports up to 1020 interrupt sources (SGI+PPI+SPI)
-- 
2.4.3