ACPI extended IRQ resources may contain a ResourceSource to specify
an alternate interrupt controller. Introduce acpi_irq_get and use it
to implement ResourceSource/IRQ domain mapping.

The new API is similar to of_irq_get and allows re-initialization
of a platform resource from the ACPI extended IRQ resource, and
provides proper behavior for probe deferral when the domain is not
yet present when called.

Signed-off-by: Agustin Vega-Frias <agust...@codeaurora.org>
---
 drivers/acpi/Makefile   |   2 +-
 drivers/acpi/gsi.c      |  98 -----------------
 drivers/acpi/irq.c      | 282 ++++++++++++++++++++++++++++++++++++++++++++++++
 drivers/base/platform.c |   9 +-
 include/linux/acpi.h    |  10 ++
 5 files changed, 301 insertions(+), 100 deletions(-)
 delete mode 100644 drivers/acpi/gsi.c
 create mode 100644 drivers/acpi/irq.c

diff --git a/drivers/acpi/Makefile b/drivers/acpi/Makefile
index 9ed0878..a391bbc 100644
--- a/drivers/acpi/Makefile
+++ b/drivers/acpi/Makefile
@@ -55,7 +55,7 @@ acpi-$(CONFIG_DEBUG_FS)               += debugfs.o
 acpi-$(CONFIG_ACPI_NUMA)       += numa.o
 acpi-$(CONFIG_ACPI_PROCFS_POWER) += cm_sbs.o
 acpi-y                         += acpi_lpat.o
-acpi-$(CONFIG_ACPI_GENERIC_GSI) += gsi.o
+acpi-$(CONFIG_ACPI_GENERIC_GSI) += irq.o
 acpi-$(CONFIG_ACPI_WATCHDOG)   += acpi_watchdog.o
 
 # These are (potentially) separate modules
diff --git a/drivers/acpi/gsi.c b/drivers/acpi/gsi.c
deleted file mode 100644
index ee9e0f2..0000000
--- a/drivers/acpi/gsi.c
+++ /dev/null
@@ -1,98 +0,0 @@
-/*
- * ACPI GSI IRQ layer
- *
- * Copyright (C) 2015 ARM Ltd.
- * Author: Lorenzo Pieralisi <lorenzo.pieral...@arm.com>
- *
- * This program is free software; you can redistribute it and/or modify
- * it under the terms of the GNU General Public License version 2 as
- * published by the Free Software Foundation.
- */
-#include <linux/acpi.h>
-#include <linux/irq.h>
-#include <linux/irqdomain.h>
-#include <linux/of.h>
-
-enum acpi_irq_model_id acpi_irq_model;
-
-static struct fwnode_handle *acpi_gsi_domain_id;
-
-/**
- * acpi_gsi_to_irq() - Retrieve the linux irq number for a given GSI
- * @gsi: GSI IRQ number to map
- * @irq: pointer where linux IRQ number is stored
- *
- * irq location updated with irq value [>0 on success, 0 on failure]
- *
- * Returns: linux IRQ number on success (>0)
- *          -EINVAL on failure
- */
-int acpi_gsi_to_irq(u32 gsi, unsigned int *irq)
-{
-       struct irq_domain *d = irq_find_matching_fwnode(acpi_gsi_domain_id,
-                                                       DOMAIN_BUS_ANY);
-
-       *irq = irq_find_mapping(d, gsi);
-       /*
-        * *irq == 0 means no mapping, that should
-        * be reported as a failure
-        */
-       return (*irq > 0) ? *irq : -EINVAL;
-}
-EXPORT_SYMBOL_GPL(acpi_gsi_to_irq);
-
-/**
- * acpi_register_gsi() - Map a GSI to a linux IRQ number
- * @dev: device for which IRQ has to be mapped
- * @gsi: GSI IRQ number
- * @trigger: trigger type of the GSI number to be mapped
- * @polarity: polarity of the GSI to be mapped
- *
- * Returns: a valid linux IRQ number on success
- *          -EINVAL on failure
- */
-int acpi_register_gsi(struct device *dev, u32 gsi, int trigger,
-                     int polarity)
-{
-       struct irq_fwspec fwspec;
-
-       if (WARN_ON(!acpi_gsi_domain_id)) {
-               pr_warn("GSI: No registered irqchip, giving up\n");
-               return -EINVAL;
-       }
-
-       fwspec.fwnode = acpi_gsi_domain_id;
-       fwspec.param[0] = gsi;
-       fwspec.param[1] = acpi_dev_get_irq_type(trigger, polarity);
-       fwspec.param_count = 2;
-
-       return irq_create_fwspec_mapping(&fwspec);
-}
-EXPORT_SYMBOL_GPL(acpi_register_gsi);
-
-/**
- * acpi_unregister_gsi() - Free a GSI<->linux IRQ number mapping
- * @gsi: GSI IRQ number
- */
-void acpi_unregister_gsi(u32 gsi)
-{
-       struct irq_domain *d = irq_find_matching_fwnode(acpi_gsi_domain_id,
-                                                       DOMAIN_BUS_ANY);
-       int irq = irq_find_mapping(d, gsi);
-
-       irq_dispose_mapping(irq);
-}
-EXPORT_SYMBOL_GPL(acpi_unregister_gsi);
-
-/**
- * acpi_set_irq_model - Setup the GSI irqdomain information
- * @model: the value assigned to acpi_irq_model
- * @fwnode: the irq_domain identifier for mapping and looking up
- *          GSI interrupts
- */
-void __init acpi_set_irq_model(enum acpi_irq_model_id model,
-                              struct fwnode_handle *fwnode)
-{
-       acpi_irq_model = model;
-       acpi_gsi_domain_id = fwnode;
-}
diff --git a/drivers/acpi/irq.c b/drivers/acpi/irq.c
new file mode 100644
index 0000000..cadc4cdd
--- /dev/null
+++ b/drivers/acpi/irq.c
@@ -0,0 +1,282 @@
+/*
+ * ACPI GSI IRQ layer
+ *
+ * Copyright (C) 2015 ARM Ltd.
+ * Author: Lorenzo Pieralisi <lorenzo.pieral...@arm.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+#include <linux/acpi.h>
+#include <linux/irq.h>
+#include <linux/irqdomain.h>
+#include <linux/of.h>
+
+enum acpi_irq_model_id acpi_irq_model;
+
+static struct fwnode_handle *acpi_gsi_domain_id;
+
+/**
+ * acpi_gsi_to_irq() - Retrieve the linux irq number for a given GSI
+ * @gsi: GSI IRQ number to map
+ * @irq: pointer where linux IRQ number is stored
+ *
+ * irq location updated with irq value [>0 on success, 0 on failure]
+ *
+ * Returns: linux IRQ number on success (>0)
+ *          -EINVAL on failure
+ */
+int acpi_gsi_to_irq(u32 gsi, unsigned int *irq)
+{
+       struct irq_domain *d = irq_find_matching_fwnode(acpi_gsi_domain_id,
+                                                       DOMAIN_BUS_ANY);
+
+       *irq = irq_find_mapping(d, gsi);
+       /*
+        * *irq == 0 means no mapping, that should
+        * be reported as a failure
+        */
+       return (*irq > 0) ? *irq : -EINVAL;
+}
+EXPORT_SYMBOL_GPL(acpi_gsi_to_irq);
+
+/**
+ * acpi_register_gsi() - Map a GSI to a linux IRQ number
+ * @dev: device for which IRQ has to be mapped
+ * @gsi: GSI IRQ number
+ * @trigger: trigger type of the GSI number to be mapped
+ * @polarity: polarity of the GSI to be mapped
+ *
+ * Returns: a valid linux IRQ number on success
+ *          -EINVAL on failure
+ */
+int acpi_register_gsi(struct device *dev, u32 gsi, int trigger,
+                     int polarity)
+{
+       struct irq_fwspec fwspec;
+
+       if (WARN_ON(!acpi_gsi_domain_id)) {
+               pr_warn("GSI: No registered irqchip, giving up\n");
+               return -EINVAL;
+       }
+
+       fwspec.fwnode = acpi_gsi_domain_id;
+       fwspec.param[0] = gsi;
+       fwspec.param[1] = acpi_dev_get_irq_type(trigger, polarity);
+       fwspec.param_count = 2;
+
+       return irq_create_fwspec_mapping(&fwspec);
+}
+EXPORT_SYMBOL_GPL(acpi_register_gsi);
+
+/**
+ * acpi_unregister_gsi() - Free a GSI<->linux IRQ number mapping
+ * @gsi: GSI IRQ number
+ */
+void acpi_unregister_gsi(u32 gsi)
+{
+       struct irq_domain *d = irq_find_matching_fwnode(acpi_gsi_domain_id,
+                                                       DOMAIN_BUS_ANY);
+       int irq = irq_find_mapping(d, gsi);
+
+       irq_dispose_mapping(irq);
+}
+EXPORT_SYMBOL_GPL(acpi_unregister_gsi);
+
+/**
+ * acpi_get_irq_source_fwhandle() - Retrieve the fwhandle of the given
+ *                                  acpi_resource_source which is used
+ *                                  as an IRQ domain id
+ * @source: acpi_resource_source to use for the lookup
+ *
+ * Returns: The appropriate IRQ fwhandle domain id
+ *          NULL on failure
+ */
+static struct fwnode_handle *
+acpi_get_irq_source_fwhandle(const struct acpi_resource_source *source)
+{
+       struct fwnode_handle *result;
+       struct acpi_device *device;
+       acpi_handle handle;
+       acpi_status status;
+
+       if (!source->string_length)
+               return acpi_gsi_domain_id;
+
+       status = acpi_get_handle(NULL, source->string_ptr, &handle);
+       if (ACPI_FAILURE(status)) {
+               pr_warn("Could not find handle for %s\n", source->string_ptr);
+               return NULL;
+       }
+
+       device = acpi_bus_get_acpi_device(handle);
+       if (!device) {
+               pr_warn("Could not get device for %s\n", source->string_ptr);
+               return NULL;
+       }
+
+       result = &device->fwnode;
+       acpi_bus_put_acpi_device(device);
+
+       return result;
+}
+
+/**
+ * Context for the resource walk used to lookup IRQ resources.
+ */
+struct acpi_irq_parse_one_ctx {
+       int rc;
+       unsigned int index;
+       unsigned long *res_flags;
+       struct irq_fwspec *fwspec;
+};
+
+/**
+ * acpi_irq_parse_one_match - Handle a matching IRQ resource
+ */
+static inline void acpi_irq_parse_one_match(struct fwnode_handle *fwnode,
+                                           u32 hwirq, u8 triggering,
+                                           u8 polarity, u8 shareable,
+                                           struct acpi_irq_parse_one_ctx *ctx)
+{
+       ctx->rc = 0;
+       *ctx->res_flags = acpi_dev_irq_flags(triggering, polarity, shareable);
+       ctx->fwspec->fwnode = fwnode;
+       ctx->fwspec->param[0] = hwirq;
+       ctx->fwspec->param[1] = acpi_dev_get_irq_type(triggering, polarity);
+       ctx->fwspec->param_count = 2;
+}
+
+/**
+ * acpi_irq_parse_one_cb - Handle the given resource
+ * @ares: resource to handle
+ * @context: context for the walk, contains the lookup index and references
+ *           to the flags and fwspec where the result is returned
+ *
+ * This is called by acpi_walk_resources passing each resource returned by
+ * the _CRS method. We only inspect IRQ resources. Since IRQ resources
+ * might contain multiple interrupts we check if the index is within this
+ * one's interrupt array, otherwise we subtract the current resource IRQ
+ * count from the lookup index to prepare for the next resource.
+ * Once a match is found we call acpi_irq_parse_one_match to populate
+ * the result and end the walk by returning AE_CTRL_TERMINATE.
+ *
+ * Return AE_OK if the walk should continue, AE_CTRL_TERMINATE if a matching
+ * IRQ resource was found.
+ */
+static acpi_status acpi_irq_parse_one_cb(struct acpi_resource *ares,
+                                        void *context)
+{
+       struct acpi_irq_parse_one_ctx *ctx = context;
+       struct acpi_resource_irq *irq;
+       struct acpi_resource_extended_irq *eirq;
+       struct fwnode_handle *fwnode;
+
+       switch (ares->type) {
+       case ACPI_RESOURCE_TYPE_IRQ:
+               irq = &ares->data.irq;
+               if (ctx->index >= irq->interrupt_count) {
+                       ctx->index -= irq->interrupt_count;
+                       return AE_OK;
+               }
+               fwnode = acpi_gsi_domain_id;
+               acpi_irq_parse_one_match(fwnode, irq->interrupts[ctx->index],
+                                        irq->triggering, irq->polarity,
+                                        irq->sharable, ctx);
+               return AE_CTRL_TERMINATE;
+       case ACPI_RESOURCE_TYPE_EXTENDED_IRQ:
+               eirq = &ares->data.extended_irq;
+               if (eirq->producer_consumer == ACPI_PRODUCER)
+                       return AE_OK;
+               if (ctx->index >= eirq->interrupt_count) {
+                       ctx->index -= eirq->interrupt_count;
+                       return AE_OK;
+               }
+               fwnode = acpi_get_irq_source_fwhandle(&eirq->resource_source);
+               acpi_irq_parse_one_match(fwnode, eirq->interrupts[ctx->index],
+                                        eirq->triggering, eirq->polarity,
+                                        eirq->sharable, ctx);
+               return AE_CTRL_TERMINATE;
+       }
+
+       return AE_OK;
+}
+
+/**
+ * acpi_irq_parse_one - Resolve an interrupt for a device
+ * @handle: the device whose interrupt is to be resolved
+ * @index: index of the interrupt to resolve
+ * @fwspec: structure irq_fwspec filled by this function
+ * @flags: resource flags filled by this function
+ *
+ * This function resolves an interrupt for a device by walking its CRS 
resources
+ * to find the appropriate ACPI IRQ resource and populating the given structure
+ * which can be used to retrieve a Linux IRQ number.
+ *
+ * Returns the result stored in ctx.rc by the callback, or -EINVAL if the given
+ * index is out of range.
+ */
+static int acpi_irq_parse_one(acpi_handle handle, unsigned int index,
+                             struct irq_fwspec *fwspec, unsigned long *flags)
+{
+       struct acpi_irq_parse_one_ctx ctx = { -EINVAL, index, flags, fwspec };
+       acpi_status status;
+
+       status = acpi_walk_resources(handle, METHOD_NAME__CRS,
+                                    acpi_irq_parse_one_cb, &ctx);
+       if (ACPI_FAILURE(status))
+               return -EINVAL;
+       return ctx.rc;
+}
+
+/**
+ * acpi_irq_get - Look for the ACPI IRQ resource with the given index and
+ *                use it to initialize the given Linux IRQ resource.
+ * @handle ACPI device handle
+ * @index  ACPI IRQ resource index to lookup
+ * @res    Linux IRQ resource to initialize
+ *
+ * Return: 0 on success
+ *         -EINVAL if an error occurs
+ *         -EPROBE_DEFER if the IRQ lookup/conversion failed
+ */
+int acpi_irq_get(acpi_handle handle, unsigned int index, struct resource *res)
+{
+       int rc;
+       struct irq_fwspec fwspec;
+       struct irq_domain *domain;
+       unsigned long flags;
+
+       rc = acpi_irq_parse_one(handle, index, &fwspec, &flags);
+       if (rc)
+               return rc;
+
+       domain = irq_find_matching_fwnode(fwspec.fwnode, DOMAIN_BUS_ANY);
+       if (!domain)
+               return -EPROBE_DEFER;
+
+       rc = irq_create_fwspec_mapping(&fwspec);
+       if (rc <= 0)
+               return -EINVAL;
+
+       res->start = rc;
+       res->end = rc;
+       res->flags = flags;
+
+       return 0;
+}
+EXPORT_SYMBOL_GPL(acpi_irq_get);
+
+/**
+ * acpi_set_irq_model - Setup the GSI irqdomain information
+ * @model: the value assigned to acpi_irq_model
+ * @fwnode: the irq_domain identifier for mapping and looking up
+ *          GSI interrupts
+ */
+void __init acpi_set_irq_model(enum acpi_irq_model_id model,
+                              struct fwnode_handle *fwnode)
+{
+       acpi_irq_model = model;
+       acpi_gsi_domain_id = fwnode;
+}
diff --git a/drivers/base/platform.c b/drivers/base/platform.c
index c4af003..61423d2 100644
--- a/drivers/base/platform.c
+++ b/drivers/base/platform.c
@@ -102,6 +102,14 @@ int platform_get_irq(struct platform_device *dev, unsigned 
int num)
        }
 
        r = platform_get_resource(dev, IORESOURCE_IRQ, num);
+       if (r && r->flags & IORESOURCE_DISABLED && ACPI_COMPANION(&dev->dev)) {
+               int ret;
+
+               ret = acpi_irq_get(ACPI_HANDLE(&dev->dev), num, r);
+               if (ret)
+                       return ret;
+       }
+
        /*
         * The resources may pass trigger flags to the irqs that need
         * to be set up. It so happens that the trigger flags for
@@ -1450,4 +1458,3 @@ void __init early_platform_cleanup(void)
                memset(&pd->dev.devres_head, 0, sizeof(pd->dev.devres_head));
        }
 }
-
diff --git a/include/linux/acpi.h b/include/linux/acpi.h
index 5b36974..03a94cd 100644
--- a/include/linux/acpi.h
+++ b/include/linux/acpi.h
@@ -1153,4 +1153,14 @@ static inline void acpi_table_upgrade(void) { }
 static inline int parse_spcr(bool earlycon) { return 0; }
 #endif
 
+#ifdef CONFIG_ACPI_GENERIC_GSI
+int acpi_irq_get(acpi_handle handle, unsigned int index, struct resource *res);
+#else
+static inline int acpi_irq_get(acpi_handle handle, unsigned int index,
+                              struct resource *res)
+{
+       return -EINVAL;
+}
+#endif
+
 #endif /*_LINUX_ACPI_H*/
-- 
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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