Message-ID: <20161020164812.GD8731@red-moon>
Date:   Thu, 20 Oct 2016 17:48:12 +0100
From:   Lorenzo Pieralisi <lorenzo.pieralisi@....com>
To:     Agustin Vega-Frias <agustinv@...eaurora.org>
Cc:     linux-kernel@...r.kernel.org, linux-acpi@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org, rjw@...ysocki.net,
        lenb@...nel.org, tglx@...utronix.de, jason@...edaemon.net,
        marc.zyngier@....com, timur@...eaurora.org, cov@...eaurora.org,
        agross@...eaurora.org, harba@...eaurora.org, jcm@...hat.com,
        msalter@...hat.com, mlangsdo@...hat.com, ahs3@...hat.com,
        astone@...hat.com, graeme.gregory@...aro.org, guohanjun@...wei.com,
        charles.garcia-tobin@....com
Subject: Re: [PATCH V5 1/2] ACPI: Add support for ResourceSource/IRQ domain
 mapping

Hi Agustin,

On Tue, Oct 18, 2016 at 01:41:48PM -0400, Agustin Vega-Frias wrote:
> This allows irqchip drivers to associate an ACPI DSDT device to
> an IRQ domain and provides support for using the ResourceSource
> in Extended IRQ Resources to find the domain and map the IRQs
> specified on that domain.
> 
> Signed-off-by: Agustin Vega-Frias <agustinv@...eaurora.org>
> ---
>  drivers/acpi/Makefile             |   1 +
>  drivers/acpi/irqdomain.c          | 141 ++++++++++++++++++++++++++++++++++++++
>  drivers/acpi/resource.c           |  21 +++---
>  include/asm-generic/vmlinux.lds.h |   1 +
>  include/linux/acpi.h              |  71 +++++++++++++++++++
>  include/linux/irqchip.h           |  17 ++++-
>  6 files changed, 240 insertions(+), 12 deletions(-)
>  create mode 100644 drivers/acpi/irqdomain.c
> 
> diff --git a/drivers/acpi/Makefile b/drivers/acpi/Makefile
> index 9ed0878..880401b 100644
> --- a/drivers/acpi/Makefile
> +++ b/drivers/acpi/Makefile
> @@ -57,6 +57,7 @@ acpi-$(CONFIG_ACPI_PROCFS_POWER) += cm_sbs.o
>  acpi-y				+= acpi_lpat.o
>  acpi-$(CONFIG_ACPI_GENERIC_GSI) += gsi.o
>  acpi-$(CONFIG_ACPI_WATCHDOG)	+= acpi_watchdog.o
> +acpi-$(CONFIG_IRQ_DOMAIN)	+= irqdomain.o
>  
>  # These are (potentially) separate modules
>  
> diff --git a/drivers/acpi/irqdomain.c b/drivers/acpi/irqdomain.c
> new file mode 100644
> index 0000000..c53b9f4
> --- /dev/null
> +++ b/drivers/acpi/irqdomain.c
> @@ -0,0 +1,141 @@
> +/*
> + * ACPI ResourceSource/IRQ domain mapping support
> + *
> + * Copyright (c) 2016, The Linux Foundation. All rights reserved.
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License version 2 and
> + * only version 2 as published by the Free Software Foundation.
> + *
> + * This program is distributed in the hope that it will be useful,
> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
> + * GNU General Public License for more details.
> + */
> +#include <linux/acpi.h>
> +#include <linux/irq.h>
> +#include <linux/irqdomain.h>
> +
> +/**
> + * acpi_irq_domain_ensure_probed() - Check if the device has registered
> + *                                   an IRQ domain and probe as necessary
> + *
> + * @device: Device to check and probe
> + *
> + * Returns: 0 on success, -ENODEV otherwise

This is not correct (ie it depends on what

struct acpi_dsdt_probe_entry.probe

returns) and I would like to take this nit as an opportunity
to take a step back and ask you a question below.

> + */
> +static int acpi_irq_domain_ensure_probed(struct acpi_device *device)
> +{
> +	struct acpi_dsdt_probe_entry *entry;
> +
> +	if (irq_find_matching_fwnode(&device->fwnode, DOMAIN_BUS_ANY) != 0)
> +		return 0;
> +
> +	for (entry = &__dsdt_acpi_probe_table;
> +	     entry < &__dsdt_acpi_probe_table_end; entry++)
> +		if (strcmp(entry->_hid, acpi_device_hid(device)) == 0)
> +			return entry->probe(device);

Through this approch we are forcing an irqchip (that by the way it
has a physical node ACPI companion by being a DSDT device object so it
could be managed by a platform driver) to be probed. The question is: is
there a reason (apart from the current ACPI resource parsing API) why
this can't be implemented through deferred probing and the device
dependencies framework Rafael is working on:

http://www.mail-archive.com/linux-kernel@vger.kernel.org/msg1246897.html

The DT layer, through the of_irq_get() API, supports probe deferral
and what I am asking you is if there is any blocking point (again,
apart from the current ACPI API) to implement the same mechanism.

I have not reviewed the previous versions so I am certainly missing
some of the bits and pieces already discussed, apologies for that.

Thanks,
Lorenzo

> +
> +	return -ENODEV;
> +}
> +
> +/**
> + * acpi_irq_domain_register_irq() - Register the mapping for an IRQ produced
> + *                                  by the given acpi_resource_source to a
> + *                                  Linux IRQ number
> + * @source: IRQ source
> + * @hwirq: Hardware IRQ number
> + * @trigger: trigger type of the IRQ number to be mapped
> + * @polarity: polarity of the IRQ to be mapped
> + *
> + * Returns: a valid linux IRQ number on success
> + *          -ENODEV if the given acpi_resource_source cannot be found
> + *          -EPROBE_DEFER if the IRQ domain has not been registered
> + *          -EINVAL for all other errors
> + */
> +int acpi_irq_domain_register_irq(const struct acpi_resource_source *source,
> +				 u32 hwirq, int trigger, int polarity)
> +{
> +	struct irq_fwspec fwspec;
> +	struct acpi_device *device;
> +	acpi_handle handle;
> +	acpi_status status;
> +	int ret;
> +
> +	/* An empty acpi_resource_source means it is a GSI */
> +	if (!source->string_length)
> +		return acpi_register_gsi(NULL, hwirq, trigger, polarity);
> +
> +	status = acpi_get_handle(NULL, source->string_ptr, &handle);
> +	if (ACPI_FAILURE(status))
> +		return -ENODEV;
> +
> +	device = acpi_bus_get_acpi_device(handle);
> +	if (!device)
> +		return -ENODEV;
> +
> +	ret = acpi_irq_domain_ensure_probed(device);
> +	if (ret)
> +		goto out_put_device;
> +
> +	fwspec.fwnode = &device->fwnode;
> +	fwspec.param[0] = hwirq;
> +	fwspec.param[1] = acpi_dev_get_irq_type(trigger, polarity);
> +	fwspec.param_count = 2;
> +
> +	ret = irq_create_fwspec_mapping(&fwspec);
> +
> +out_put_device:
> +	acpi_bus_put_acpi_device(device);
> +
> +	return ret;
> +}
> +EXPORT_SYMBOL_GPL(acpi_irq_domain_register_irq);
> +
> +/**
> + * acpi_irq_domain_unregister_irq() - Delete the mapping for an IRQ produced
> + *                                    by the given acpi_resource_source to a
> + *                                    Linux IRQ number
> + * @source: IRQ source
> + * @hwirq: Hardware IRQ number
> + *
> + * Returns: 0 on success
> + *          -ENODEV if the given acpi_resource_source cannot be found
> + *          -EINVAL for all other errors
> + */
> +int acpi_irq_domain_unregister_irq(const struct acpi_resource_source *source,
> +				   u32 hwirq)
> +{
> +	struct irq_domain *domain;
> +	struct acpi_device *device;
> +	acpi_handle handle;
> +	acpi_status status;
> +	int ret = 0;
> +
> +	if (!source->string_length) {
> +		acpi_unregister_gsi(hwirq);
> +		return 0;
> +	}
> +
> +	status = acpi_get_handle(NULL, source->string_ptr, &handle);
> +	if (ACPI_FAILURE(status))
> +		return -ENODEV;
> +
> +	device = acpi_bus_get_acpi_device(handle);
> +	if (!device)
> +		return -ENODEV;
> +
> +	domain = irq_find_matching_fwnode(&device->fwnode, DOMAIN_BUS_ANY);
> +	if (!domain) {
> +		ret = -EINVAL;
> +		goto out_put_device;
> +	}
> +
> +	irq_dispose_mapping(irq_find_mapping(domain, hwirq));
> +
> +out_put_device:
> +	acpi_bus_put_acpi_device(device);
> +
> +	return ret;
> +}
> +EXPORT_SYMBOL_GPL(acpi_irq_domain_unregister_irq);
> diff --git a/drivers/acpi/resource.c b/drivers/acpi/resource.c
> index 56241eb..3fb7abf 100644
> --- a/drivers/acpi/resource.c
> +++ b/drivers/acpi/resource.c
> @@ -381,14 +381,15 @@ static void acpi_dev_irqresource_disabled(struct resource *res, u32 gsi)
>  	res->flags = IORESOURCE_IRQ | IORESOURCE_DISABLED | IORESOURCE_UNSET;
>  }
>  
> -static void acpi_dev_get_irqresource(struct resource *res, u32 gsi,
> +static void acpi_dev_get_irqresource(struct resource *res, u32 hwirq,
> +				     const struct acpi_resource_source *source,
>  				     u8 triggering, u8 polarity, u8 shareable,
>  				     bool legacy)
>  {
>  	int irq, p, t;
>  
> -	if (!valid_IRQ(gsi)) {
> -		acpi_dev_irqresource_disabled(res, gsi);
> +	if ((source->string_length == 0) && !valid_IRQ(hwirq)) {
> +		acpi_dev_irqresource_disabled(res, hwirq);
>  		return;
>  	}
>  
> @@ -402,25 +403,25 @@ static void acpi_dev_get_irqresource(struct resource *res, u32 gsi,
>  	 * using extended IRQ descriptors we take the IRQ configuration
>  	 * from _CRS directly.
>  	 */
> -	if (legacy && !acpi_get_override_irq(gsi, &t, &p)) {
> +	if (legacy && !acpi_get_override_irq(hwirq, &t, &p)) {
>  		u8 trig = t ? ACPI_LEVEL_SENSITIVE : ACPI_EDGE_SENSITIVE;
>  		u8 pol = p ? ACPI_ACTIVE_LOW : ACPI_ACTIVE_HIGH;
>  
>  		if (triggering != trig || polarity != pol) {
> -			pr_warning("ACPI: IRQ %d override to %s, %s\n", gsi,
> -				   t ? "level" : "edge", p ? "low" : "high");
> +			pr_warn("ACPI: IRQ %d override to %s, %s\n", hwirq,
> +				t ? "level" : "edge", p ? "low" : "high");
>  			triggering = trig;
>  			polarity = pol;
>  		}
>  	}
>  
>  	res->flags = acpi_dev_irq_flags(triggering, polarity, shareable);
> -	irq = acpi_register_gsi(NULL, gsi, triggering, polarity);
> +	irq = acpi_irq_domain_register_irq(source, hwirq, triggering, polarity);
>  	if (irq >= 0) {
>  		res->start = irq;
>  		res->end = irq;
>  	} else {
> -		acpi_dev_irqresource_disabled(res, gsi);
> +		acpi_dev_irqresource_disabled(res, hwirq);
>  	}
>  }
>  
> @@ -446,6 +447,7 @@ static void acpi_dev_get_irqresource(struct resource *res, u32 gsi,
>  bool acpi_dev_resource_interrupt(struct acpi_resource *ares, int index,
>  				 struct resource *res)
>  {
> +	const struct acpi_resource_source dummy = { 0, 0, NULL };
>  	struct acpi_resource_irq *irq;
>  	struct acpi_resource_extended_irq *ext_irq;
>  
> @@ -460,7 +462,7 @@ bool acpi_dev_resource_interrupt(struct acpi_resource *ares, int index,
>  			acpi_dev_irqresource_disabled(res, 0);
>  			return false;
>  		}
> -		acpi_dev_get_irqresource(res, irq->interrupts[index],
> +		acpi_dev_get_irqresource(res, irq->interrupts[index], &dummy,
>  					 irq->triggering, irq->polarity,
>  					 irq->sharable, true);
>  		break;
> @@ -471,6 +473,7 @@ bool acpi_dev_resource_interrupt(struct acpi_resource *ares, int index,
>  			return false;
>  		}
>  		acpi_dev_get_irqresource(res, ext_irq->interrupts[index],
> +					 &ext_irq->resource_source,
>  					 ext_irq->triggering, ext_irq->polarity,
>  					 ext_irq->sharable, false);
>  		break;
> diff --git a/include/asm-generic/vmlinux.lds.h b/include/asm-generic/vmlinux.lds.h
> index 3074796..f808afdc 100644
> --- a/include/asm-generic/vmlinux.lds.h
> +++ b/include/asm-generic/vmlinux.lds.h
> @@ -563,6 +563,7 @@
>  	IRQCHIP_OF_MATCH_TABLE()					\
>  	ACPI_PROBE_TABLE(irqchip)					\
>  	ACPI_PROBE_TABLE(clksrc)					\
> +	ACPI_PROBE_TABLE(dsdt)						\
>  	EARLYCON_TABLE()
>  
>  #define INIT_TEXT							\
> diff --git a/include/linux/acpi.h b/include/linux/acpi.h
> index ddbeda6..bb1a838 100644
> --- a/include/linux/acpi.h
> +++ b/include/linux/acpi.h
> @@ -26,6 +26,7 @@
>  #include <linux/resource_ext.h>
>  #include <linux/device.h>
>  #include <linux/property.h>
> +#include <linux/irqdomain.h>
>  
>  #ifndef _LINUX
>  #define _LINUX
> @@ -321,6 +322,31 @@ void acpi_set_irq_model(enum acpi_irq_model_id model,
>   */
>  void acpi_unregister_gsi (u32 gsi);
>  
> +#ifdef CONFIG_IRQ_DOMAIN
> +
> +int acpi_irq_domain_register_irq(const struct acpi_resource_source *source,
> +				 u32 hwirq, int trigger, int polarity);
> +int acpi_irq_domain_unregister_irq(const struct acpi_resource_source *source,
> +				   u32 hwirq);
> +
> +#else
> +
> +static inline int acpi_irq_domain_register_irq(
> +	const struct acpi_resource_source *source, u32 hwirq, int trigger,
> +	int polarity)
> +{
> +	return acpi_register_gsi(NULL, hwirq, trigger, polarity);
> +}
> +
> +static inline int acpi_irq_domain_unregister_irq(
> +	const struct acpi_resource_source *source,  u32 hwirq)
> +{
> +	acpi_unregister_gsi(hwirq);
> +	return 0;
> +}
> +
> +#endif /* CONFIG_IRQ_DOMAIN */
> +
>  struct pci_dev;
>  
>  int acpi_pci_irq_enable (struct pci_dev *dev);
> @@ -1024,6 +1050,34 @@ struct acpi_probe_entry {
>  					  (&ACPI_PROBE_TABLE_END(t) -	\
>  					   &ACPI_PROBE_TABLE(t)));	\
>  	})
> +
> +/* Length of Hardware ID field in DSDT entries as per ACPI spec */
> +#define ACPI_HID_LEN 9
> +
> +typedef int (*acpi_dsdt_handler)(struct acpi_device *);
> +
> +/**
> + * struct acpi_probe_dsdt_entry - boot-time probing entry for DSDT devices
> + * @hid:		_HID of the device
> + * @fn:		Callback to the driver being probed
> + * @driver_data:	Sideband data provided back to the driver
> + */
> +struct acpi_dsdt_probe_entry {
> +	__u8 _hid[ACPI_HID_LEN];
> +	acpi_dsdt_handler probe;
> +};
> +
> +#define ACPI_DECLARE_DSDT_PROBE_ENTRY(name, hid, fn)			\
> +	static const struct acpi_dsdt_probe_entry __acpi_probe_##name	\
> +		__used __section(__dsdt_acpi_probe_table) =		\
> +		{							\
> +			._hid = hid,					\
> +			.probe = fn,					\
> +		}
> +
> +extern struct acpi_dsdt_probe_entry __dsdt_acpi_probe_table;
> +extern struct acpi_dsdt_probe_entry __dsdt_acpi_probe_table_end;
> +
>  #else
>  static inline int acpi_dev_get_property(struct acpi_device *adev,
>  					const char *name, acpi_object_type type,
> @@ -1101,8 +1155,25 @@ static inline struct fwnode_handle *acpi_get_next_subnode(struct device *dev,
>  		     (void *) data }
>  
>  #define acpi_probe_device_table(t)	({ int __r = 0; __r;})
> +
> +#define ACPI_DECLARE_DSDT_PROBE_ENTRY(name, hid, fn)			\
> +	static const void *__acpi_probe_##name[]			\
> +		__attribute__((unused))				\
> +		 = { (void *) hid,					\
> +		     (void *) fn }
> +
>  #endif
>  
> +#define MADT_IRQCHIP_ACPI_DECLARE(name, subtable, validate, data, fn)	\
> +	ACPI_DECLARE_PROBE_ENTRY(irqchip, name, ACPI_SIG_MADT,		\
> +				 subtable, validate, data, fn)
> +
> +#define DSDT_IRQCHIP_ACPI_DECLARE(name, hid, fn)	\
> +	ACPI_DECLARE_DSDT_PROBE_ENTRY(name, hid, fn)
> +
> +#define __IRQCHIP_ACPI_DECLARE(_a1, _a2, _a3, _a4, _a5, type, ...)	\
> +	type##_IRQCHIP_ACPI_DECLARE
> +
>  #ifdef CONFIG_ACPI_TABLE_UPGRADE
>  void acpi_table_upgrade(void);
>  #else
> diff --git a/include/linux/irqchip.h b/include/linux/irqchip.h
> index 89c34b2..c2d0c12 100644
> --- a/include/linux/irqchip.h
> +++ b/include/linux/irqchip.h
> @@ -29,6 +29,10 @@
>  /*
>   * This macro must be used by the different irqchip drivers to declare
>   * the association between their version and their initialization function.
> + * Two syntaxes are supported depending on the table where the irqchip device
> + * is declared:
> + *
> + * - MADT irqchip syntax, which requires the following five arguments:
>   *
>   * @name: name that must be unique accross all IRQCHIP_ACPI_DECLARE of the
>   * same file.
> @@ -37,10 +41,17 @@
>   *            Can be NULL.
>   * @data: data to be checked by the validate function.
>   * @fn: initialization function
> + *
> + * - DSDT irqchip syntax, which requires the following three arguments:
> + *
> + * @name: name that must be unique across all IRQCHIP_ACPI_DECLARE of the
> + * same file.
> + * @hid: _HID of the DSDT device
> + * @fn: initialization function
>   */
> -#define IRQCHIP_ACPI_DECLARE(name, subtable, validate, data, fn)	\
> -	ACPI_DECLARE_PROBE_ENTRY(irqchip, name, ACPI_SIG_MADT, 		\
> -				 subtable, validate, data, fn)
> +
> +#define IRQCHIP_ACPI_DECLARE(...)					\
> +	__IRQCHIP_ACPI_DECLARE(__VA_ARGS__, MADT, _unused, DSDT)(__VA_ARGS__)
>  
>  #ifdef CONFIG_IRQCHIP
>  void irqchip_init(void);
> -- 
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> Qualcomm Technologies, Inc. is a member of the Code Aurora Forum, a Linux Foundation Collaborative Project.
> 
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