Re: [RFC PATCH 01/33] irqchip/gic-v3: Add redistributor iterator

[Shanker Donthineni]

Hi Marc,


On 01/17/2017 04:20 AM, Marc Zyngier wrote:
> In order to discover the VLPI properties, we need to iterate over
> the redistributor regions. As we already have code that does this,
> let's factor it out and make it slightly more generic.
>
> Signed-off-by: Marc Zyngier <marc.zyngier@xxxxxxx>
> ---
>   drivers/irqchip/irq-gic-v3.c | 77
> ++++++++++++++++++++++++++++++++------------
>   1 file changed, 56 insertions(+), 21 deletions(-)
>
> diff --git a/drivers/irqchip/irq-gic-v3.c b/drivers/irqchip/irq-gic-v3.c
> index c132f29..5cadec0 100644
> --- a/drivers/irqchip/irq-gic-v3.c
> +++ b/drivers/irqchip/irq-gic-v3.c
> @@ -421,24 +421,15 @@ static void __init gic_dist_init(void)
>   		gic_write_irouter(affinity, base + GICD_IROUTER + i * 8);
>   }
>   
> -static int gic_populate_rdist(void)
> +static int gic_scan_rdist_properties(int (*fn)(struct redist_region *,
> +					       void __iomem *))
I don't see this function is parsing GICR properties, may be it makes 
readable on changing name to gic_redist_iterator().

>   {
> -	unsigned long mpidr = cpu_logical_map(smp_processor_id());
> -	u64 typer;
> -	u32 aff;
> +	int ret = 0;
For readability purpose set  ret = ENODEV, to cover error case where 
gic_data.nr_redist_regions == 0.
>   	int i;
>   
> -	/*
> -	 * Convert affinity to a 32bit value that can be matched to
> -	 * GICR_TYPER bits [63:32].
> -	 */
> -	aff = (MPIDR_AFFINITY_LEVEL(mpidr, 3) << 24 |
> -	       MPIDR_AFFINITY_LEVEL(mpidr, 2) << 16 |
> -	       MPIDR_AFFINITY_LEVEL(mpidr, 1) << 8 |
> -	       MPIDR_AFFINITY_LEVEL(mpidr, 0));
> -
>   	for (i = 0; i < gic_data.nr_redist_regions; i++) {
>   		void __iomem *ptr =
> gic_data.redist_regions[i].redist_base;
> +		u64 typer;
>   		u32 reg;
>   
>   		reg = readl_relaxed(ptr + GICR_PIDR2) &
> GIC_PIDR2_ARCH_MASK;
> @@ -450,14 +441,14 @@ static int gic_populate_rdist(void)
>   
>   		do {
>   			typer = gic_read_typer(ptr + GICR_TYPER);
> -			if ((typer >> 32) == aff) {
> -				u64 offset = ptr -
> gic_data.redist_regions[i].redist_base;
> -				gic_data_rdist_rd_base() = ptr;
> -				gic_data_rdist()->phys_base =
> gic_data.redist_regions[i].phys_base + offset;
> -				pr_info("CPU%d: found redistributor %lx
> region %d:%pa\n",
> -					smp_processor_id(), mpidr, i,
> -					&gic_data_rdist()->phys_base);
> +			ret = fn(gic_data.redist_regions + i, ptr);
> +			switch (ret) {
> +			case 0:
>   				return 0;
> +			case -1:
> +				break;
> +			default:
> +				ret = 0;
>   			}
>   
>   			if (gic_data.redist_regions[i].single_redist)
> @@ -473,9 +464,53 @@ static int gic_populate_rdist(void)
>   		} while (!(typer & GICR_TYPER_LAST));
>   
>   
> +	if (ret == -1)
> +		ret = -ENODEV;
> +
__gic_populate_rdist() returns 1 to try next entry in the list. We 
should not return value 0 here if no matching entry is found otherwise 
the gic_populate_rdist() assumes that it found the corresponding GICR.

+	return 0;
+}
+
+static int __gic_populate_rdist(struct redist_region *region, void
__iomem *ptr)
+{
+	unsigned long mpidr = cpu_logical_map(smp_processor_id());
+	u64 typer;
+	u32 aff;
+
+	/*
+	 * Convert affinity to a 32bit value that can be matched to
+	 * GICR_TYPER bits [63:32].
+	 */
+	aff = (MPIDR_AFFINITY_LEVEL(mpidr, 3) << 24 |
+	       MPIDR_AFFINITY_LEVEL(mpidr, 2) << 16 |
+	       MPIDR_AFFINITY_LEVEL(mpidr, 1) << 8 |
+	       MPIDR_AFFINITY_LEVEL(mpidr, 0));
+
+	typer = gic_read_typer(ptr + GICR_TYPER);
+	if ((typer >> 32) == aff) {
+		u64 offset = ptr - region->redist_base;
+		gic_data_rdist_rd_base() = ptr;
+		gic_data_rdist()->phys_base = region->phys_base + offset;
+
+		pr_info("CPU%d: found redistributor %lx region %d:%pa\n",
+			smp_processor_id(), mpidr,
+			(int)(region - gic_data.redist_regions),
+			&gic_data_rdist()->phys_base);
+		return 0;
+	}
+
+	/* Try next one */
+	return 1;
+}
+
+static int gic_populate_rdist(void)
+{
+	if (gic_scan_rdist_properties(__gic_populate_rdist) == 0)

what about 'if (!gic_scan_rdist_properties(__gic_populate_rdist))'?
> +		return 0;
> +
>   	/* We couldn't even deal with ourselves... */
>   	WARN(true, "CPU%d: mpidr %lx has no re-distributor!\n",
> -	     smp_processor_id(), mpidr);
> +	     smp_processor_id(),
> +	     (unsigned long)cpu_logical_map(smp_processor_id()));
>   	return -ENODEV;
>   }
>   

--
Shanker Donthineni
Qualcomm Datacenter Technologies, Inc. as an affiliate of Qualcomm Technologies, Inc.
Qualcomm Technologies, Inc. is a member of the Code Aurora Forum, a Linux Foundation Collaborative Project.