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Subject[PATCH] irqchip/gicv3: Add support for Range Selector (RS) feature
Date
A new feature Range Selector (RS) has been added to GIC specification
in order to support more than 16 CPUs at affinity level 0. New fields
are introduced in SGI system registers (ICC_SGI0R_EL1, ICC_SGI1R_EL1
and ICC_ASGI1R_EL1) to relax an artificial limit of 16 at level 0.

- A new RSS field in ICC_CTLR_EL3, ICC_CTLR_EL1 and ICV_CTLR_EL1:
[18] - Range Selector Support (RSS)
0b0 = Targeted SGIs with affinity level 0 values of 0-15 are supported.
0b1 = Targeted SGIs with affinity level 0 values of 0-255 are supported.

- A new RS field in ICC_SGI0R_EL1, ICC_SGI1R_EL1 and ICC_ASGI1R_EL1:
[47:44] - RangeSelector (RS) which group of 16 TargetList[n] field
TargetList[n] represents aff0 value ((RS*16)+n)
When ICC_CTLR_EL3.RSS==0 or ICC_CTLR_EL1.RSS==0, RS is RES0.

- A new RSS field in GICD_TYPER:
[26] - Range Selector Support (RSS)
0b0 = Targeted SGIs with affinity level 0 values of 0-15 are supported.
0b1 = Targeted SGIs with affinity level 0 values of 0-255 are supported.

Signed-off-by: Shanker Donthineni <shankerd@codeaurora.org>
---
drivers/irqchip/irq-gic-v3.c | 79 ++++++++++++++++++++------------------
include/linux/irqchip/arm-gic-v3.h | 4 ++
2 files changed, 46 insertions(+), 37 deletions(-)

diff --git a/drivers/irqchip/irq-gic-v3.c b/drivers/irqchip/irq-gic-v3.c
index 984c3ec..ba98c94 100644
--- a/drivers/irqchip/irq-gic-v3.c
+++ b/drivers/irqchip/irq-gic-v3.c
@@ -56,6 +56,7 @@ struct gic_chip_data {
u64 redist_stride;
u32 nr_redist_regions;
unsigned int irq_nr;
+ bool has_rss;
struct partition_desc *ppi_descs[16];
};

@@ -483,6 +484,9 @@ static int gic_populate_rdist(void)

static void gic_cpu_sys_reg_init(void)
{
+ int cpu = smp_processor_id();
+ bool rss;
+
/*
* Need to check that the SRE bit has actually been set. If
* not, it means that SRE is disabled at EL2. We're going to
@@ -514,6 +518,15 @@ static void gic_cpu_sys_reg_init(void)

/* ... and let's hit the road... */
gic_write_grpen1(1);
+
+ /* GIC CPU interface has RSS capability? */
+ rss = !!(read_sysreg_s(SYS_ICC_CTLR_EL1) & ICC_CTLR_EL1_RSS);
+
+ if (gic_data.has_rss != rss)
+ pr_info("Broken hardware, mismatch RSS, SGIs may not work\n");
+ else if ((cpu_logical_map(cpu) & 0xf0) && (!rss))
+ pr_crit("MPIDR bits[7..4] must be zero, cpu=%d\n", cpu);
+
}

static int gic_dist_supports_lpis(void)
@@ -554,43 +567,13 @@ static int gic_starting_cpu(unsigned int cpu)
return 0;
}

-static u16 gic_compute_target_list(int *base_cpu, const struct cpumask *mask,
- unsigned long cluster_id)
-{
- int next_cpu, cpu = *base_cpu;
- unsigned long mpidr = cpu_logical_map(cpu);
- u16 tlist = 0;
-
- while (cpu < nr_cpu_ids) {
- /*
- * If we ever get a cluster of more than 16 CPUs, just
- * scream and skip that CPU.
- */
- if (WARN_ON((mpidr & 0xff) >= 16))
- goto out;
-
- tlist |= 1 << (mpidr & 0xf);
-
- next_cpu = cpumask_next(cpu, mask);
- if (next_cpu >= nr_cpu_ids)
- goto out;
- cpu = next_cpu;
-
- mpidr = cpu_logical_map(cpu);
-
- if (cluster_id != (mpidr & ~0xffUL)) {
- cpu--;
- goto out;
- }
- }
-out:
- *base_cpu = cpu;
- return tlist;
-}
-
#define MPIDR_TO_SGI_AFFINITY(cluster_id, level) \
(MPIDR_AFFINITY_LEVEL(cluster_id, level) \
<< ICC_SGI1R_AFFINITY_## level ##_SHIFT)
+#define MPIDR_RS(mpidr) (((mpidr) & 0xF0) >> 4)
+#define MPIDR_TO_SGI_TARGETLIST(mpidr) (1 << ((mpidr) & 0xF))
+#define MPIDR_TO_SGI_CLUSTER_ID(mpidr) (mpidr & ~0xF)
+#define MPIDR_TO_SGI_RS(mpidr) (MPIDR_RS(mpidr) << ICC_SGI1R_RS_SHIFT)

static void gic_send_sgi(u64 cluster_id, u16 tlist, unsigned int irq)
{
@@ -600,6 +583,7 @@ static void gic_send_sgi(u64 cluster_id, u16 tlist, unsigned int irq)
MPIDR_TO_SGI_AFFINITY(cluster_id, 2) |
irq << ICC_SGI1R_SGI_ID_SHIFT |
MPIDR_TO_SGI_AFFINITY(cluster_id, 1) |
+ MPIDR_TO_SGI_RS(cluster_id) |
tlist << ICC_SGI1R_TARGET_LIST_SHIFT);

pr_debug("CPU%d: ICC_SGI1R_EL1 %llx\n", smp_processor_id(), val);
@@ -620,10 +604,27 @@ static void gic_raise_softirq(const struct cpumask *mask, unsigned int irq)
smp_wmb();

for_each_cpu(cpu, mask) {
- unsigned long cluster_id = cpu_logical_map(cpu) & ~0xffUL;
- u16 tlist;
+ u64 mpidr = cpu_logical_map(cpu);
+ u64 cluster_id = MPIDR_TO_SGI_CLUSTER_ID(mpidr);
+ u16 tlist = 0;
+ int next_cpu;
+
+ if (WARN_ON((!gic_data.has_rss) && MPIDR_RS(mpidr)))
+ continue;
+
+ /* Prepare TARGETLIST which have the same cluster_id */
+ do {
+ tlist |= MPIDR_TO_SGI_TARGETLIST(mpidr);
+ next_cpu = cpumask_next(cpu, mask);
+ if (next_cpu >= nr_cpu_ids)
+ break;
+
+ mpidr = cpu_logical_map(next_cpu);
+ if (cluster_id != MPIDR_TO_SGI_CLUSTER_ID(mpidr))
+ break;
+ cpu = next_cpu;
+ } while (true);

- tlist = gic_compute_target_list(&cpu, mask, cluster_id);
gic_send_sgi(cluster_id, tlist, irq);
}

@@ -959,6 +960,10 @@ static int __init gic_init_bases(void __iomem *dist_base,
goto out_free;
}

+ gic_data.has_rss = !!(typer & GICD_TYPER_RSS);
+ pr_info("Distributor has %s Range Selector support\n",
+ gic_data.has_rss ? "" : "no");
+
set_handle_irq(gic_handle_irq);

if (IS_ENABLED(CONFIG_ARM_GIC_V3_ITS) && gic_dist_supports_lpis())
diff --git a/include/linux/irqchip/arm-gic-v3.h b/include/linux/irqchip/arm-gic-v3.h
index 6a1f87f..eb9ff9b 100644
--- a/include/linux/irqchip/arm-gic-v3.h
+++ b/include/linux/irqchip/arm-gic-v3.h
@@ -68,6 +68,7 @@
#define GICD_CTLR_ENABLE_SS_G1 (1U << 1)
#define GICD_CTLR_ENABLE_SS_G0 (1U << 0)

+#define GICD_TYPER_RSS (1U << 26)
#define GICD_TYPER_LPIS (1U << 17)
#define GICD_TYPER_MBIS (1U << 16)

@@ -377,6 +378,7 @@
#define ICC_CTLR_EL1_SEIS_MASK (0x1 << ICC_CTLR_EL1_SEIS_SHIFT)
#define ICC_CTLR_EL1_A3V_SHIFT 15
#define ICC_CTLR_EL1_A3V_MASK (0x1 << ICC_CTLR_EL1_A3V_SHIFT)
+#define ICC_CTLR_EL1_RSS (0x1 << 18)
#define ICC_PMR_EL1_SHIFT 0
#define ICC_PMR_EL1_MASK (0xff << ICC_PMR_EL1_SHIFT)
#define ICC_BPR0_EL1_SHIFT 0
@@ -465,6 +467,8 @@
#define ICC_SGI1R_AFFINITY_2_SHIFT 32
#define ICC_SGI1R_AFFINITY_2_MASK (0xffULL << ICC_SGI1R_AFFINITY_2_SHIFT)
#define ICC_SGI1R_IRQ_ROUTING_MODE_BIT 40
+#define ICC_SGI1R_RS_SHIFT 44
+#define ICC_SGI1R_RS_MASK (0xfULL << ICC_SGI1R_RS_SHIFT)
#define ICC_SGI1R_AFFINITY_3_SHIFT 48
#define ICC_SGI1R_AFFINITY_3_MASK (0xffULL << ICC_SGI1R_AFFINITY_3_SHIFT)

--
Qualcomm Datacenter Technologies, Inc. on behalf of the Qualcomm Technologies, Inc.
Qualcomm Technologies, Inc. is a member of the Code Aurora Forum, a Linux Foundation Collaborative Project.
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