Date:   Mon, 8 Oct 2018 15:18:29 +0530
From:   Lokesh Vutla <lokeshvutla@...com>
To:     Marc Zyngier <marc.zyngier@....com>
CC:     Nishanth Menon <nm@...com>, Tero Kristo <t-kristo@...com>,
        <tglx@...utronix.de>, <jason@...edaemon.net>,
        Rob Herring <robh+dt@...nel.org>,
        Santosh Shilimkar <ssantosh@...nel.org>,
        Device Tree Mailing List <devicetree@...r.kernel.org>,
        Linux ARM Mailing List <linux-arm-kernel@...ts.infradead.org>,
        <linux-kernel@...r.kernel.org>, Sekhar Nori <nsekhar@...com>
Subject: Re: [PATCH 2/2] irqchip: ti-sci-intr: Add support for Interrupt
 Router driver

Hi Marc,

On 10/6/2018 3:25 PM, Marc Zyngier wrote:
> Hi Lokesh,
> 
> On Sat, 06 Oct 2018 08:28:12 +0100,
> Lokesh Vutla <lokeshvutla@...com> wrote:
>>
>> Texas Instruments' K3 generation SoCs has an IP Interrupt Router
>> that does allows for multiplexing of input interrupts to host
>> interrupt controller. Interrupt Router inputs are either from a
>> peripheral or from an Interrupt Aggregator which is another
>> interrupt controller.
>>
>> Configuration of the interrupt router registers can only be done by
>> a system co-processor and the driver needs to send a message to this
>> co processor over TISCI protocol.
> 
> I assume that this co-processor only deals with the routing itself,
> and doesn't need to be talked to during interrupt processing, right?

Yes, that's right.

> 
>>
>> Add support for Interrupt Router driver over TISCI protocol.
>>
>> Signed-off-by: Lokesh Vutla <lokeshvutla@...com>
>> ---
>>  MAINTAINERS                       |   1 +
>>  drivers/irqchip/Kconfig           |  11 +
>>  drivers/irqchip/Makefile          |   1 +
>>  drivers/irqchip/irq-ti-sci-intr.c | 325 ++++++++++++++++++++++++++++++
>>  4 files changed, 338 insertions(+)
>>  create mode 100644 drivers/irqchip/irq-ti-sci-intr.c
>>
>> diff --git a/MAINTAINERS b/MAINTAINERS
>> index a23778b68d74..cf3c834f8cee 100644
>> --- a/MAINTAINERS
>> +++ b/MAINTAINERS
>> @@ -14626,6 +14626,7 @@ F:	Documentation/devicetree/bindings/clock/ti,sci-clk.txt
>>  F:	drivers/clk/keystone/sci-clk.c
>>  F:	drivers/reset/reset-ti-sci.c
>>  F:	Documentation/devicetree/bindings/interrupt-controller/ti,sci-intr.txt
>> +F:	drivers/irqchip/irq-ti-sci-intr.c
>>  
>>  THANKO'S RAREMONO AM/FM/SW RADIO RECEIVER USB DRIVER
>>  M:	Hans Verkuil <hverkuil@...all.nl>
>> diff --git a/drivers/irqchip/Kconfig b/drivers/irqchip/Kconfig
>> index 96451b581452..9a965fe22043 100644
>> --- a/drivers/irqchip/Kconfig
>> +++ b/drivers/irqchip/Kconfig
>> @@ -374,6 +374,17 @@ config QCOM_PDC
>>  	  Power Domain Controller driver to manage and configure wakeup
>>  	  IRQs for Qualcomm Technologies Inc (QTI) mobile chips.
>>  
>> +config TI_SCI_INTR_IRQCHIP
>> +	tristate "TISCI based Interrupt Router irqchip driver"
>> +	depends on TI_SCI_PROTOCOL && ARCH_K3
>> +	select IRQ_DOMAIN
>> +	select IRQ_DOMAIN_HIERARCHY
>> +	help
>> +	  This enables the irqchip driver support for K3 Interrupt router
>> +	  over TI System Control Interface available on some new TI's SoCs.
>> +	  If you wish to use interrupt router irq resources managed by the
>> +	  TI System Controller, say Y here. Otherwise, say N.
> 
> I don't really see the point of making this user-selectable. If you're
> compiling support for a given platform, this platform configuration
> fragment should itself select the necessary dependencies for the
> system to work as expected. Here, you are leaving the choice to the
> user, with a 50% chance of getting a system that doesn't boot...

There are 2 reasons why I made it tristate:
- Not all interrupts go through this irqchip(At least in the AM6 SoC
using this). Most of the legacy peripherals still are directly connected
to GIC
- TI_SCI_PROTOCOL is defined as tristate.

If you still feel I should not make it user-selectable, I can drop it.

> 
>> +
>>  endmenu
>>  
>>  config SIFIVE_PLIC
>> diff --git a/drivers/irqchip/Makefile b/drivers/irqchip/Makefile
>> index b822199445ff..44bf65606d60 100644
>> --- a/drivers/irqchip/Makefile
>> +++ b/drivers/irqchip/Makefile
>> @@ -89,3 +89,4 @@ obj-$(CONFIG_GOLDFISH_PIC) 		+= irq-goldfish-pic.o
>>  obj-$(CONFIG_NDS32)			+= irq-ativic32.o
>>  obj-$(CONFIG_QCOM_PDC)			+= qcom-pdc.o
>>  obj-$(CONFIG_SIFIVE_PLIC)		+= irq-sifive-plic.o
>> +obj-$(CONFIG_TI_SCI_INTR_IRQCHIP)	+= irq-ti-sci-intr.o
>> diff --git a/drivers/irqchip/irq-ti-sci-intr.c b/drivers/irqchip/irq-ti-sci-intr.c
>> new file mode 100644
>> index 000000000000..f04fe6da1b09
>> --- /dev/null
>> +++ b/drivers/irqchip/irq-ti-sci-intr.c
>> @@ -0,0 +1,325 @@
>> +// SPDX-License-Identifier: GPL-2.0
>> +/*
>> + * Texas Instruments' K3 Interrupt Router irqchip driver
>> + *
>> + * Copyright (C) 2018 Texas Instruments Incorporated - http://www.ti.com/
>> + *	Lokesh Vutla <lokeshvutla@...com>
>> + */
>> +
>> +#include <linux/err.h>
>> +#include <linux/io.h>
>> +#include <linux/irqchip.h>
>> +#include <linux/of_platform.h>
>> +#include <linux/of_address.h>
>> +#include <linux/of_irq.h>
>> +#include <linux/module.h>
>> +#include <linux/moduleparam.h>
>> +#include <linux/irqdomain.h>
>> +#include <linux/soc/ti/ti_sci_protocol.h>
>> +
>> +#define TI_SCI_DEV_ID_MASK	0xffff
>> +#define TI_SCI_DEV_ID_SHIFT	16
>> +#define TI_SCI_IRQ_ID_MASK	0xffff
>> +#define TI_SCI_IRQ_ID_SHIFT	0
>> +#define TI_SCI_IS_EVENT_IRQ	BIT(31)
>> +
>> +#define HWIRQ_TO_DEVID(HWIRQ)	(((HWIRQ) >> (TI_SCI_DEV_ID_SHIFT)) & \
>> +				 (TI_SCI_DEV_ID_MASK))
>> +#define HWIRQ_TO_IRQID(HWIRQ)	((HWIRQ) & (TI_SCI_IRQ_ID_MASK))
> 
> nit: s/(HWIRQ)/(hwirq)/g

okay.

> 
>> +
>> +/**
>> + * struct ti_sci_intr_irq_domain - Structure representing a TISCI based
>> + *				   Interrupt Router IRQ domain.
>> + * @sci:	Pointer to TISCI handle
>> + * @dst_irq:	TISCI resource pointer representing destination irq controller.
>> + * @dst_id:	TISCI device ID of the destination irq controller.
>> + */
>> +struct ti_sci_intr_irq_domain {
>> +	const struct ti_sci_handle *sci;
>> +	struct ti_sci_resource *dst_irq;
>> +	u16 dst_id;
>> +};
>> +
>> +/**
>> + * struct ti_sci_intr_irq_desc - Description of an Interrupt Router IRQ
>> + * @src_id:		TISCI device ID of the IRQ source
>> + * @src_index:		IRQ source index within the device.
>> + * @dst_irq:		Destination host IRQ.
>> + */
>> +struct ti_sci_intr_irq_desc {
>> +	u16 src_id;
>> +	u16 src_index;
>> +	u16 dst_irq;
>> +};
> 
> Oh great. So this is reinventing the GICv3 ITS, only for SPIs. :-(
> 
> Now, this structure seems completely useless, see below.
> 
>> +
>> +static struct irq_chip ti_sci_intr_irq_chip = {
>> +	.name			= "INTR",
>> +	.irq_eoi		= irq_chip_eoi_parent,
>> +	.irq_mask		= irq_chip_mask_parent,
>> +	.irq_unmask		= irq_chip_unmask_parent,
>> +	.irq_retrigger		= irq_chip_retrigger_hierarchy,
>> +	.irq_set_type		= irq_chip_set_type_parent,
>> +	.irq_set_affinity	= irq_chip_set_affinity_parent,
>> +};
>> +
>> +/**
>> + * ti_sci_intr_irq_domain_translate() - Retrieve hwirq and type from
>> + *					IRQ firmware specific handler.
>> + * @domain:	Pointer to IRQ domain
>> + * @fwspec:	Pointer to IRQ specific firmware structure
>> + * @hwirq:	IRQ number identified by hardware
>> + * @type:	IRQ type
>> + *
>> + * Return 0 if all went ok else appropriate error.
>> + */
>> +static int ti_sci_intr_irq_domain_translate(struct irq_domain *domain,
>> +					    struct irq_fwspec *fwspec,
>> +					    unsigned long *hwirq,
>> +					    unsigned int *type)
>> +{
>> +	if (is_of_node(fwspec->fwnode)) {
>> +		if (fwspec->param_count != 3)
>> +			return -EINVAL;
>> +
>> +		*hwirq = ((fwspec->param[0] & TI_SCI_DEV_ID_MASK) <<
>> +			  TI_SCI_DEV_ID_SHIFT) |
>> +			 (fwspec->param[1] & TI_SCI_IRQ_ID_MASK);
> 
> Maybe it would make sense to have a macro that hides this:

okay.

> 
>       	       *hwirq = FWSPEC_TO_HWIRQ(fwspec);
> 
>> +		*type = fwspec->param[2];
>> +
>> +		return 0;
>> +	}
>> +
>> +	return -EINVAL;
>> +}
>> +
>> +static inline void ti_sci_intr_delete_desc(struct ti_sci_intr_irq_domain *intr,
>> +					   struct ti_sci_intr_irq_desc *desc)
>> +{
>> +	intr->sci->ops.rm_irq_ops.free_direct_irq(intr->sci, desc->src_id,
>> +						  desc->src_index,
>> +						  intr->dst_id, desc->dst_irq);
> 
> This looks horrible. Why doesn't your firmware interface have a helper
> functions that hides this? Something like:
> 
> 	ti_sci_free_direct_irq(intr, src_id, src_index, dst_irq);
> 
> and you could even add some error checking.

All existing TISCI users follow the same convention, so I did not bother adding 
any such wrapper. Will update TISCI with these wrappers and see what firmware 
maintainer says.

> 
>> +	pr_debug("%s: IRQ deleted from src = %d, src_index = %d, to dst = %d, dst_irq = %d\n",
>> +		 __func__, desc->src_id, desc->src_index, intr->dst_id,
>> +		desc->dst_irq);
> 
> And put this where it belongs (in the helper function).
> 
>> +}
>> +
>> +/**
>> + * ti_sci_intr_irq_domain_free() - Free the specified IRQs from the domain.
>> + * @domain:	Domain to which the irqs belong
>> + * @virq:	Linux virtual IRQ to be freed.
>> + * @nr_irqs:	Number of continuous irqs to be freed
>> + */
>> +static void ti_sci_intr_irq_domain_free(struct irq_domain *domain,
>> +					unsigned int virq, unsigned int nr_irqs)
>> +{
>> +	struct ti_sci_intr_irq_domain *intr = domain->host_data;
>> +	struct ti_sci_intr_irq_desc *desc;
>> +	struct irq_data *data;
>> +	int i;
>> +
>> +	intr = domain->host_data;
>> +
>> +	for (i = 0; i < nr_irqs; i++) {
>> +		data = irq_domain_get_irq_data(domain, virq + i);
>> +
>> +		desc = irq_data_get_irq_chip_data(data);
>> +
>> +		ti_sci_intr_delete_desc(intr, desc);
>> +		irq_domain_free_irqs_parent(domain, virq, 1);
>> +		irq_domain_reset_irq_data(data);
>> +		ti_sci_release_resource(intr->dst_irq, desc->dst_irq);
>> +		kfree(desc);
>> +	}
>> +}
>> +
>> +/**
>> + * allocate_gic_irq() - Allocate GIC specific IRQ
>> + * @domain:	Point to the interrupt router IRQ domain
>> + * @dev:	TISCI device IRQ generating the IRQ
>> + * @irq:	IRQ offset within the device
>> + * @flags:	Corresponding flags to the IRQ
>> + *
>> + * Returns pointer to irq descriptor if all went well else appropriate
>> + * error pointer.
>> + */
>> +static struct ti_sci_intr_irq_desc *allocate_gic_irq(struct irq_domain *domain,
>> +						     unsigned int virq,
>> +						     u16 dev, u16 irq,
>> +						     u32 flags)
>> +{
>> +	struct ti_sci_intr_irq_domain *intr = domain->host_data;
>> +	struct ti_sci_intr_irq_desc *desc;
>> +	struct irq_fwspec fwspec;
>> +	int err;
>> +
>> +	if (!irq_domain_get_of_node(domain->parent))
>> +		return ERR_PTR(-EINVAL);
>> +
>> +	desc = kzalloc(sizeof(*desc), GFP_KERNEL);
>> +	if (!desc)
>> +		return ERR_PTR(-ENOMEM);
>> +
>> +	desc->src_id = dev;
>> +	desc->src_index = irq;
>> +	desc->dst_irq = ti_sci_get_free_resource(intr->dst_irq);
> 
> I don't think this structure serves any purpose. src_id and src_index
> are just a decomposition of hwirq. dst_irq is the GIC interrupt, which
> is stored... by the GIC driver. Also, it is worth realising that
> you're allocating per-interrupt data, but none of the per-interrupt
> callbacks are using it. In my book, that's a sure sign that this
> structure is pointless.

hmm..you are right, these 3 fields can be dropped completely.

> 
> Am I missing anything here? >
>> +
>> +	fwspec.fwnode = domain->parent->fwnode;
>> +	fwspec.param_count = 3;
>> +	fwspec.param[0] = 0;	/* SPI */
>> +	fwspec.param[1] = desc->dst_irq - 32; /* SPI offset */
>> +	fwspec.param[2] = flags & IRQ_TYPE_SENSE_MASK;
>> +
>> +	err = irq_domain_alloc_irqs_parent(domain, virq, 1, &fwspec);
>> +	if (err)
>> +		goto err_irqs;
>> +
>> +	pr_debug("%s: IRQ requested from src = %d, src_index = %d, to dst = %d, dst_irq = %d\n",
>> +		 __func__, desc->src_id, desc->src_index, intr->dst_id,
>> +		 desc->dst_irq);
>> +
>> +	err = intr->sci->ops.rm_irq_ops.set_direct_irq(intr->sci, desc->src_id,
>> +						       desc->src_index,
>> +						       intr->dst_id,
>> +						       desc->dst_irq);
> 
> Same remarks about the horrible interface.
> 
>> +	if (err) {
>> +		pr_err("%s: IRQ allocation failed from src = %d, src_index = %d to dst_id = %d, dst_irq = %d",
>> +		       __func__, desc->src_id, desc->src_index, intr->dst_id,
>> +		       desc->dst_irq);
>> +		goto err_msg;
>> +	}
>> +
>> +	return desc;
>> +
>> +err_msg:
>> +	irq_domain_free_irqs_parent(domain, virq, 1);
>> +err_irqs:
>> +	ti_sci_release_resource(intr->dst_irq, desc->dst_irq);
>> +	kfree(desc);
>> +	return ERR_PTR(err);
>> +}
>> +
>> +/**
>> + * ti_sci_intr_irq_domain_alloc() - Allocate Interrupt router IRQs
>> + * @domain:	Point to the interrupt router IRQ domain
>> + * @virq:	Corresponding Linux virtual IRQ number
>> + * @nr_irqs:	Continuous irqs to be allocated
>> + * @data:	Pointer to firmware specifier
>> + *
>> + * Return 0 if all went well else appropriate error value.
>> + */
>> +static int ti_sci_intr_irq_domain_alloc(struct irq_domain *domain,
>> +					unsigned int virq, unsigned int nr_irqs,
>> +					void *data)
>> +{
>> +	struct irq_fwspec *fwspec = data;
>> +	struct ti_sci_intr_irq_desc *desc;
>> +	unsigned long hwirq;
>> +	u16 src_id, src_index;
>> +	int i, err;
>> +	u32 type;
>> +
>> +	err = ti_sci_intr_irq_domain_translate(domain, fwspec, &hwirq, &type);
>> +	if (err)
>> +		return err;
>> +
>> +	src_id = HWIRQ_TO_DEVID(hwirq);
>> +	src_index = HWIRQ_TO_IRQID(hwirq);
>> +
>> +	for (i = 0; i < nr_irqs; i++) {
>> +		desc = allocate_gic_irq(domain, virq + i, src_id, src_index + i,
>> +					type);
>> +		if (IS_ERR(desc))
>> +			/* ToDO: Clean already allocated IRQs */
>> +			return PTR_ERR(desc);
> 
> Please address this. But it also worth realising that this code will
> never be called with nr_irqs!=1 (that's only for things like PCI
> Multi-MSI).

will fix it in v2.

> 
>> +
>> +		err = irq_domain_set_hwirq_and_chip(domain, virq + i, hwirq + i,
>> +						    &ti_sci_intr_irq_chip,
>> +						    desc);
>> +		if (err)
>> +			return err;
>> +	}
>> +
>> +	return 0;
>> +}
>> +
>> +static const struct irq_domain_ops ti_sci_intr_irq_domain_ops = {
>> +	.alloc		= ti_sci_intr_irq_domain_alloc,
>> +	.free		= ti_sci_intr_irq_domain_free,
>> +	.translate	= ti_sci_intr_irq_domain_translate,
>> +};
>> +
>> +static int ti_sci_intr_irq_domain_probe(struct platform_device *pdev)
>> +{
>> +	struct irq_domain *parent_domain, *domain;
>> +	struct ti_sci_intr_irq_domain *intr;
>> +	struct device_node *parent_node;
>> +	struct device *dev = &pdev->dev;
>> +	int ret;
>> +
>> +	parent_node = of_irq_find_parent(dev_of_node(dev));
>> +	if (!parent_node) {
>> +		dev_err(dev, "Failed to get IRQ parent node\n");
>> +		return -ENODEV;
>> +	}
>> +
>> +	parent_domain = irq_find_host(parent_node);
>> +	if (!parent_domain) {
>> +		dev_err(dev, "Failed to find IRQ parent domain\n");
>> +		return -ENODEV;
>> +	}
>> +
>> +	intr = devm_kzalloc(dev, sizeof(*intr), GFP_KERNEL);
>> +	if (!intr)
>> +		return -ENOMEM;
>> +
>> +	intr->sci = devm_ti_sci_get_by_phandle(dev, "ti,sci");
>> +	if (IS_ERR(intr->sci)) {
>> +		ret = PTR_ERR(intr->sci);
>> +		if (ret != -EPROBE_DEFER)
>> +			dev_err(dev, "ti,sci read fail %d\n", ret);
>> +		intr->sci = NULL;
>> +		return ret;
>> +	}
>> +
>> +	intr->dst_irq = devm_ti_sci_get_of_resource(intr->sci, dev,
>> +						    "ti,sci-rm-range-girq");
>> +	if (IS_ERR(intr->dst_irq)) {
>> +		dev_err(dev, "Destination irq resource allocation failed\n");
>> +		return PTR_ERR(intr->dst_irq);
>> +	}
>> +
>> +	ret = of_property_read_u32(dev_of_node(dev), "ti,sci-dst-id",
>> +				   (u32 *)&intr->dst_id);
>> +	if (ret) {
>> +		dev_err(dev, "missing 'ti,sci-dst-id' property\n");
>> +		return -EINVAL;
>> +	}
> 
> Do you expect other drivers to require similar resource request? If
> so, It might be worth getting the firmware interface to do that
> work. Specially the "give me my SCI" part.

I tried to consolidate sci resource part under devm_ti_sci_get_of_resource() api 
but dst-id is something that is used by irqchip driver. So couldn't consolidate 
it and had to get it from dt in the driver probe.

Thanks and regards,
Lokesh

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