Re: [PATCH v4 06/10] irqchip / GICv3: Add ACPI support for GICv3+ initialization

[Marc Zyngier]

On 29/07/15 11:08, Hanjun Guo wrote:
> From: Tomasz Nowicki <tomasz.nowicki@xxxxxxxxxx>
> 
> With the refator of gic_of_init(), GICv3/4 can be initialized
> by gic_init_bases() with gic distributor base address and gic
> redistributor region(s).
> 
> So get the redistributor region base addresses from MADT GIC
> redistributor subtable, and the distributor base address from
> GICD subtable to init GICv3 irqchip in ACPI way.
> 
> Note: GIC redistributor base address may also be provided in
> GICC structures on systems supporting GICv3 and above if the GIC
> Redistributors are not in the always-on power domain, this
> patch didn't implement such feature yet.
> 
> Signed-off-by: Tomasz Nowicki <tomasz.nowicki@xxxxxxxxxx>
> [hj: Rework this patch and fix multi issues]
> Signed-off-by: Hanjun Guo <hanjun.guo@xxxxxxxxxx>
> ---
>  drivers/irqchip/irq-gic-v3.c | 174 +++++++++++++++++++++++++++++++++++++++++--
>  1 file changed, 169 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/irqchip/irq-gic-v3.c b/drivers/irqchip/irq-gic-v3.c
> index c0b96c6..ebc5604 100644
> --- a/drivers/irqchip/irq-gic-v3.c
> +++ b/drivers/irqchip/irq-gic-v3.c
> @@ -15,6 +15,7 @@
>   * along with this program.  If not, see <http://www.gnu.org/licenses/>.
>   */
>  
> +#include <linux/acpi.h>
>  #include <linux/cpu.h>
>  #include <linux/cpu_pm.h>
>  #include <linux/delay.h>
> @@ -25,6 +26,7 @@
>  #include <linux/percpu.h>
>  #include <linux/slab.h>
>  
> +#include <linux/irqchip/arm-gic-acpi.h>
>  #include <linux/irqchip/arm-gic-v3.h>
>  
>  #include <asm/cputype.h>
> @@ -802,7 +804,8 @@ static int __init gic_init_bases(void __iomem *dist_base,
>  	set_handle_irq(gic_handle_irq);
>  
>  	if (IS_ENABLED(CONFIG_ARM_GIC_V3_ITS) && gic_dist_supports_lpis())
> -		its_init(domain_token, &gic_data.rdists, gic_data.domain);
> +		its_init(irq_domain_token_to_of_node(domain_token),
> +			 &gic_data.rdists, gic_data.domain);

This doesn't make much sense. The first parameter to its_init is indeed
supposed to be an of_node, but what is the point of calling its_init if
you *know* you don't have the necessary topological information to parse
the firmware tables?

I don't see *any* code that is going to parse the ITS table in this
series, so please don't call its_init passing a NULL pointer to it. This
is just gross.

>  
>  	gic_smp_init();
>  	gic_dist_init();
> @@ -818,6 +821,16 @@ out_free:
>  	return err;
>  }
>  
> +static int __init detect_distributor(void __iomem *dist_base)

We do have a naming convention in this file. All functions start with gic_.

> +{
> +	u32 reg = readl_relaxed(dist_base + GICD_PIDR2) & GIC_PIDR2_ARCH_MASK;
> +
> +	if (reg != GIC_PIDR2_ARCH_GICv3 && reg != GIC_PIDR2_ARCH_GICv4)
> +		return -ENODEV;
> +
> +	return 0;
> +}

This function doesn't detect anything, it validates that we have
something sensible. Please rename it to gic_validate_dist_version, or
something similar.

> +
>  #ifdef CONFIG_OF
>  static int __init gic_of_init(struct device_node *node, struct device_node *parent)
>  {
> @@ -825,7 +838,6 @@ static int __init gic_of_init(struct device_node *node, struct device_node *pare
>  	struct redist_region *rdist_regs;
>  	u64 redist_stride;
>  	u32 nr_redist_regions;
> -	u32 reg;
>  	int err, i;
>  
>  	dist_base = of_iomap(node, 0);
> @@ -835,11 +847,10 @@ static int __init gic_of_init(struct device_node *node, struct device_node *pare
>  		return -ENXIO;
>  	}
>  
> -	reg = readl_relaxed(dist_base + GICD_PIDR2) & GIC_PIDR2_ARCH_MASK;
> -	if (reg != GIC_PIDR2_ARCH_GICv3 && reg != GIC_PIDR2_ARCH_GICv4) {
> +	err = detect_distributor(dist_base);
> +	if (err) {
>  		pr_err("%s: no distributor detected, giving up\n",
>  			node->full_name);
> -		err = -ENODEV;
>  		goto out_unmap_dist;
>  	}
>  
> @@ -887,3 +898,156 @@ out_unmap_dist:
>  
>  IRQCHIP_DECLARE(gic_v3, "arm,gic-v3", gic_of_init);
>  #endif
> +
> +#ifdef CONFIG_ACPI
> +static struct redist_region *redist_regs __initdata;
> +static u32 nr_redist_regions __initdata;
> +static phys_addr_t dist_phys_base __initdata;
> +
> +static int __init
> +gic_acpi_register_redist(u64 phys_base, u64 size)

A physical address must use phys_addr_t.

> +{
> +	struct redist_region *redist_regs_new;
> +	void __iomem *redist_base;
> +
> +	redist_regs_new = krealloc(redist_regs,
> +				   sizeof(*redist_regs) * (nr_redist_regions + 1),
> +				   GFP_KERNEL);

NAK. If you have multiple regions, you count them, you allocate the
right number of regions. This will be far more efficient than doing this
realloc dance. It is not like we're not parsing the tables a zillion
times already. Doing it one more time won't hurt.

> +	if (!redist_regs_new) {
> +		pr_err("Couldn't allocate resource for GICR region\n");
> +		return -ENOMEM;
> +	}
> +
> +	redist_regs = redist_regs_new;
> +
> +	redist_base = ioremap(phys_base, size);
> +	if (!redist_base) {
> +		pr_err("Couldn't map GICR region @%llx\n", phys_base);
> +		return -ENOMEM;
> +	}
> +
> +	redist_regs[nr_redist_regions].phys_base = phys_base;
> +	redist_regs[nr_redist_regions].redist_base = redist_base;
> +	nr_redist_regions++;
> +	return 0;
> +}
> +
> +static int __init
> +gic_acpi_parse_madt_redist(struct acpi_subtable_header *header,
> +			const unsigned long end)
> +{
> +	struct acpi_madt_generic_redistributor *redist;
> +
> +	if (BAD_MADT_ENTRY(header, end))
> +		return -EINVAL;
> +
> +	redist = (struct acpi_madt_generic_redistributor *)header;
> +	if (!redist->base_address)
> +		return -EINVAL;
> +
> +	return gic_acpi_register_redist(redist->base_address, redist->length);
> +}
> +
> +static int __init
> +gic_acpi_parse_madt_distributor(struct acpi_subtable_header *header,
> +				const unsigned long end)
> +{

How many versions of gic_acpi_parse_madt_distributor are we going to
get? Why isn't the ACPI parsing in a common file? Why do I have to read
the same code on and on until my eyes bleed?

> +	struct acpi_madt_generic_distributor *dist;
> +
> +	dist = (struct acpi_madt_generic_distributor *)header;
> +
> +	if (BAD_MADT_ENTRY(dist, end))
> +		return -EINVAL;
> +
> +	dist_phys_base = dist->base_address;
> +	return 0;
> +}
> +
> +static int gic_acpi_gsi_desc_populate(struct acpi_gsi_descriptor *data,
> +				      u32 gsi, unsigned int irq_type)
> +{
> +	/*
> +	 * Encode GSI and triggering information the way the GIC likes
> +	 * them.
> +	 */
> +	if (WARN_ON(gsi < 16))
> +		return -EINVAL;
> +
> +	if (gsi >= 32) {
> +		data->param[0] = 0;		/* SPI */
> +		data->param[1] = gsi - 32;
> +		data->param[2] = irq_type;
> +	} else {
> +		data->param[0] = 1; 		/* PPI */
> +		data->param[1] = gsi - 16;
> +		data->param[2] = 0xff << 4 | irq_type;
> +	}
> +
> +	data->param_count = 3;
> +
> +	return 0;
> +}
> +
> +static int __init
> +gic_acpi_init(struct acpi_table_header *table)
> +{
> +	int count, i, err = 0;
> +	void __iomem *dist_base;
> +
> +	/* Get distributor base address */
> +	count = acpi_parse_entries(ACPI_SIG_MADT,
> +				sizeof(struct acpi_table_madt),
> +				gic_acpi_parse_madt_distributor, table,
> +				ACPI_MADT_TYPE_GENERIC_DISTRIBUTOR, 0);
> +	if (count <= 0) {
> +		pr_err("No valid GICD entry exist\n");
> +		return -EINVAL;
> +	} else if (count > 1) {
> +		pr_err("More than one GICD entry detected\n");
> +		return -EINVAL;
> +	}
> +
> +	dist_base = ioremap(dist_phys_base, ACPI_GICV3_DIST_MEM_SIZE);
> +	if (!dist_base) {
> +		pr_err("Unable to map GICD registers\n");
> +		return -ENOMEM;
> +	}
> +
> +	err = detect_distributor(dist_base);
> +	if (err) {
> +		pr_err("No distributor detected at @%p, giving up", dist_base);
> +		goto out_dist_unmap;
> +	}
> +
> +	/* Collect redistributor base addresses */
> +	count = acpi_parse_entries(ACPI_SIG_MADT,
> +			sizeof(struct acpi_table_madt),
> +			gic_acpi_parse_madt_redist, table,
> +			ACPI_MADT_TYPE_GENERIC_REDISTRIBUTOR, 0);
> +	if (count <= 0) {
> +		pr_info("No valid GICR entries exist\n");
> +		err = -EINVAL;
> +		goto out_redist_unmap;
> +	}
> +
> +	err = gic_init_bases(dist_base, redist_regs, nr_redist_regions, 0,
> +			     (void *)ACPI_IRQ_MODEL_GIC);

There is no other global identifier for GICv3? It feels a bit weird to
use the same ID as GICv2 (though probably not harmful as you can't have
both as the same time). What are you planning to use for the ITS then?
You must make sure you have a global namespace.

> +	if (err)
> +		goto out_redist_unmap;
> +
> +	acpi_set_irq_model(ACPI_IRQ_MODEL_GIC, ACPI_IRQ_MODEL_GIC,
> +			   gic_acpi_gsi_desc_populate);
> +	return 0;
> +
> +out_redist_unmap:
> +	for (i = 0; i < nr_redist_regions; i++)
> +		if (redist_regs[i].redist_base)
> +			iounmap(redist_regs[i].redist_base);
> +	kfree(redist_regs);
> +out_dist_unmap:
> +	iounmap(dist_base);
> +	return err;
> +}
> +IRQCHIP_ACPI_DECLARE(gic_v3, ACPI_MADT_GIC_VERSION_V3, gic_acpi_init);
> +IRQCHIP_ACPI_DECLARE(gic_v4, ACPI_MADT_GIC_VERSION_V4, gic_acpi_init);

As mentioned before, this doesn't work.

> +#endif
> 

Thanks,

	M.
-- 
Jazz is not dead. It just smells funny...
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