irqchip: Provide irq-msi-lib

All irqdomains which provide MSI parent domain functionality for per device
MSI domains need to provide a select() callback for the irqdomain and a
function to initialize the child domain.

Most of these functions would just be copy&paste with minimal
modifications, so provide a library function which implements the required
functionality and is customizable via parent_domain::msi_parent_ops. The
check for the supported bus tokens in msi_lib_init_dev_msi_info() is
expanded step by step within the next patches.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Anna-Maria Behnsen <anna-maria@linutronix.de>
Signed-off-by: Shivamurthy Shastri <shivamurthy.shastri@linutronix.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/r/20240623142234.840975799@linutronix.de

diff --git a/drivers/irqchip/Kconfig b/drivers/irqchip/Kconfig
index 14464716bacbb7a7b154a07e19174da213e99210..2bf8d940504c53a5ea2bf5644dd8edb8cca1cf89 100644 (file)
--- a/drivers/irqchip/Kconfig
+++ b/drivers/irqchip/Kconfig
@@ -74,6 +74,9 @@ config ARM_VIC_NR
          The maximum number of VICs available in the system, for
          power management.
 
+config IRQ_MSI_LIB
+       bool
+
 config ARMADA_370_XP_IRQ
        bool
        select GENERIC_IRQ_CHIP

diff --git a/drivers/irqchip/Makefile b/drivers/irqchip/Makefile
index d9dc3d99aaa863faffcfeb568581405265d80ccd..72c7f62894110525b40731dad40508a55bbf4192 100644 (file)
--- a/drivers/irqchip/Makefile
+++ b/drivers/irqchip/Makefile
@@ -29,6 +29,7 @@ obj-$(CONFIG_ARCH_SPEAR3XX)           += spear-shirq.o
 obj-$(CONFIG_ARM_GIC)                  += irq-gic.o irq-gic-common.o
 obj-$(CONFIG_ARM_GIC_PM)               += irq-gic-pm.o
 obj-$(CONFIG_ARCH_REALVIEW)            += irq-gic-realview.o
+obj-$(CONFIG_IRQ_MSI_LIB)              += irq-msi-lib.o
 obj-$(CONFIG_ARM_GIC_V2M)              += irq-gic-v2m.o
 obj-$(CONFIG_ARM_GIC_V3)               += irq-gic-v3.o irq-gic-v3-mbi.o irq-gic-common.o
 obj-$(CONFIG_ARM_GIC_V3_ITS)           += irq-gic-v3-its.o irq-gic-v3-its-platform-msi.o irq-gic-v4.o

diff --git a/drivers/irqchip/irq-msi-lib.c b/drivers/irqchip/irq-msi-lib.c
new file mode 100644 (file)
index 0000000..ec1a10f
--- /dev/null
+++ b/drivers/irqchip/irq-msi-lib.c
@@ -0,0 +1,112 @@
+// SPDX-License-Identifier: GPL-2.0-only
+// Copyright (C) 2022 Linutronix GmbH
+// Copyright (C) 2022 Intel
+
+#include <linux/export.h>
+
+#include "irq-msi-lib.h"
+
+/**
+ * msi_lib_init_dev_msi_info - Domain info setup for MSI domains
+ * @dev:               The device for which the domain is created for
+ * @domain:            The domain providing this callback
+ * @real_parent:       The real parent domain of the domain to be initialized
+ *                     which might be a domain built on top of @domain or
+ *                     @domain itself
+ * @info:              The domain info for the domain to be initialize
+ *
+ * This function is to be used for all types of MSI domains above the root
+ * parent domain and any intermediates. The topmost parent domain specific
+ * functionality is determined via @real_parent.
+ *
+ * All intermediate domains between the root and the device domain must
+ * have either msi_parent_ops.init_dev_msi_info = msi_parent_init_dev_msi_info
+ * or invoke it down the line.
+ */
+bool msi_lib_init_dev_msi_info(struct device *dev, struct irq_domain *domain,
+                              struct irq_domain *real_parent,
+                              struct msi_domain_info *info)
+{
+       const struct msi_parent_ops *pops = real_parent->msi_parent_ops;
+
+       /* Parent ops available? */
+       if (WARN_ON_ONCE(!pops))
+               return false;
+
+       /*
+        * MSI parent domain specific settings. For now there is only the
+        * root parent domain, e.g. NEXUS, acting as a MSI parent, but it is
+        * possible to stack MSI parents. See x86 vector -> irq remapping
+        */
+       if (domain->bus_token == pops->bus_select_token) {
+               if (WARN_ON_ONCE(domain != real_parent))
+                       return false;
+       } else {
+               WARN_ON_ONCE(1);
+               return false;
+       }
+
+       /* Is the target domain bus token supported? */
+       switch(info->bus_token) {
+       default:
+               /*
+                * This should never be reached. See
+                * msi_lib_irq_domain_select()
+                */
+               WARN_ON_ONCE(1);
+               return false;
+       }
+
+       /*
+        * Mask out the domain specific MSI feature flags which are not
+        * supported by the real parent.
+        */
+       info->flags                     &= pops->supported_flags;
+       /* Enforce the required flags */
+       info->flags                     |= pops->required_flags;
+
+       /* Chip updates for all child bus types */
+       if (!info->chip->irq_eoi)
+               info->chip->irq_eoi     = irq_chip_eoi_parent;
+
+       /*
+        * The device MSI domain can never have a set affinity callback. It
+        * always has to rely on the parent domain to handle affinity
+        * settings. The device MSI domain just has to write the resulting
+        * MSI message into the hardware which is the whole purpose of the
+        * device MSI domain aside of mask/unmask which is provided e.g. by
+        * PCI/MSI device domains.
+        */
+       info->chip->irq_set_affinity    = msi_domain_set_affinity;
+       return true;
+}
+EXPORT_SYMBOL_GPL(msi_lib_init_dev_msi_info);
+
+/**
+ * msi_lib_irq_domain_select - Shared select function for NEXUS domains
+ * @d:         Pointer to the irq domain on which select is invoked
+ * @fwspec:    Firmware spec describing what is searched
+ * @bus_token: The bus token for which a matching irq domain is looked up
+ *
+ * Returns:    %0 if @d is not what is being looked for
+ *
+ *             %1 if @d is either the domain which is directly searched for or
+ *                if @d is providing the parent MSI domain for the functionality
+ *                      requested with @bus_token.
+ */
+int msi_lib_irq_domain_select(struct irq_domain *d, struct irq_fwspec *fwspec,
+                             enum irq_domain_bus_token bus_token)
+{
+       const struct msi_parent_ops *ops = d->msi_parent_ops;
+       u32 busmask = BIT(bus_token);
+
+       if (fwspec->fwnode != d->fwnode || fwspec->param_count != 0)
+               return 0;
+
+       /* Handle pure domain searches */
+       if (bus_token == ops->bus_select_token)
+               return 1;
+
+       return ops && !!(ops->bus_select_mask & busmask);
+}
+EXPORT_SYMBOL_GPL(msi_lib_irq_domain_select);

diff --git a/drivers/irqchip/irq-msi-lib.h b/drivers/irqchip/irq-msi-lib.h
new file mode 100644 (file)
index 0000000..f0706cc
--- /dev/null
+++ b/drivers/irqchip/irq-msi-lib.h
@@ -0,0 +1,19 @@
+// SPDX-License-Identifier: GPL-2.0-only
+// Copyright (C) 2022 Linutronix GmbH
+// Copyright (C) 2022 Intel
+
+#ifndef _DRIVERS_IRQCHIP_IRQ_MSI_LIB_H
+#define _DRIVERS_IRQCHIP_IRQ_MSI_LIB_H
+
+#include <linux/bits.h>
+#include <linux/irqdomain.h>
+#include <linux/msi.h>
+
+int msi_lib_irq_domain_select(struct irq_domain *d, struct irq_fwspec *fwspec,
+                             enum irq_domain_bus_token bus_token);
+
+bool msi_lib_init_dev_msi_info(struct device *dev, struct irq_domain *domain,
+                              struct irq_domain *real_parent,
+                              struct msi_domain_info *info);
+
+#endif /* _DRIVERS_IRQCHIP_IRQ_MSI_LIB_H */