drivers/irqchip/irq-msi-lib.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 // Copyright (C) 2022 Linutronix GmbH
   3 // Copyright (C) 2022 Intel
   4
   5 #include <linux/export.h>
   6
   7 #include "irq-msi-lib.h"
   8
   9 /**
  10  * msi_lib_init_dev_msi_info - Domain info setup for MSI domains
  11  * @dev:                The device for which the domain is created for
  12  * @domain:             The domain providing this callback
  13  * @real_parent:        The real parent domain of the domain to be initialized
  14  *                      which might be a domain built on top of @domain or
  15  *                      @domain itself
  16  * @info:               The domain info for the domain to be initialize
  17  *
  18  * This function is to be used for all types of MSI domains above the root
  19  * parent domain and any intermediates. The topmost parent domain specific
  20  * functionality is determined via @real_parent.
  21  *
  22  * All intermediate domains between the root and the device domain must
  23  * have either msi_parent_ops.init_dev_msi_info = msi_parent_init_dev_msi_info
  24  * or invoke it down the line.
  25  */
  26 bool msi_lib_init_dev_msi_info(struct device *dev, struct irq_domain *domain,
  27                                struct irq_domain *real_parent,
  28                                struct msi_domain_info *info)
  29 {
  30         const struct msi_parent_ops *pops = real_parent->msi_parent_ops;
  31         u32 required_flags;
  32
  33         /* Parent ops available? */
  34         if (WARN_ON_ONCE(!pops))
  35                 return false;
  36
  37         /*
  38          * MSI parent domain specific settings. For now there is only the
  39          * root parent domain, e.g. NEXUS, acting as a MSI parent, but it is
  40          * possible to stack MSI parents. See x86 vector -> irq remapping
  41          */
  42         if (domain->bus_token == pops->bus_select_token) {
  43                 if (WARN_ON_ONCE(domain != real_parent))
  44                         return false;
  45         } else {
  46                 WARN_ON_ONCE(1);
  47                 return false;
  48         }
  49
  50         required_flags = pops->required_flags;
  51
  52         /* Is the target domain bus token supported? */
  53         switch(info->bus_token) {
  54         case DOMAIN_BUS_PCI_DEVICE_MSI:
  55         case DOMAIN_BUS_PCI_DEVICE_MSIX:
  56                 if (WARN_ON_ONCE(!IS_ENABLED(CONFIG_PCI_MSI)))
  57                         return false;
  58
  59                 break;
  60         case DOMAIN_BUS_DEVICE_MSI:
  61                 /*
  62                  * Per device MSI should never have any MSI feature bits
  63                  * set. It's sole purpose is to create a dumb interrupt
  64                  * chip which has a device specific irq_write_msi_msg()
  65                  * callback.
  66                  */
  67                 if (WARN_ON_ONCE(info->flags))
  68                         return false;
  69
  70                 /* Core managed MSI descriptors */
  71                 info->flags = MSI_FLAG_ALLOC_SIMPLE_MSI_DESCS | MSI_FLAG_FREE_MSI_DESCS;
  72                 fallthrough;
  73         case DOMAIN_BUS_WIRED_TO_MSI:
  74                 /* Remove PCI specific flags */
  75                 required_flags &= ~MSI_FLAG_PCI_MSI_MASK_PARENT;
  76                 break;
  77         default:
  78                 /*
  79                  * This should never be reached. See
  80                  * msi_lib_irq_domain_select()
  81                  */
  82                 WARN_ON_ONCE(1);
  83                 return false;
  84         }
  85
  86         /*
  87          * Mask out the domain specific MSI feature flags which are not
  88          * supported by the real parent.
  89          */
  90         info->flags                     &= pops->supported_flags;
  91         /* Enforce the required flags */
  92         info->flags                     |= required_flags;
  93
  94         /* Chip updates for all child bus types */
  95         if (!info->chip->irq_eoi)
  96                 info->chip->irq_eoi     = irq_chip_eoi_parent;
  97         if (!info->chip->irq_ack)
  98                 info->chip->irq_ack     = irq_chip_ack_parent;
  99
 100         /*
 101          * The device MSI domain can never have a set affinity callback. It
 102          * always has to rely on the parent domain to handle affinity
 103          * settings. The device MSI domain just has to write the resulting
 104          * MSI message into the hardware which is the whole purpose of the
 105          * device MSI domain aside of mask/unmask which is provided e.g. by
 106          * PCI/MSI device domains.
 107          */
 108         info->chip->irq_set_affinity    = msi_domain_set_affinity;
 109         return true;
 110 }
 111 EXPORT_SYMBOL_GPL(msi_lib_init_dev_msi_info);
 112
 113 /**
 114  * msi_lib_irq_domain_select - Shared select function for NEXUS domains
 115  * @d:          Pointer to the irq domain on which select is invoked
 116  * @fwspec:     Firmware spec describing what is searched
 117  * @bus_token:  The bus token for which a matching irq domain is looked up
 118  *
 119  * Returns:     %0 if @d is not what is being looked for
 120  *
 121  *              %1 if @d is either the domain which is directly searched for or
 122  *                 if @d is providing the parent MSI domain for the functionality
 123  *                       requested with @bus_token.
 124  */
 125 int msi_lib_irq_domain_select(struct irq_domain *d, struct irq_fwspec *fwspec,
 126                               enum irq_domain_bus_token bus_token)
 127 {
 128         const struct msi_parent_ops *ops = d->msi_parent_ops;
 129         u32 busmask = BIT(bus_token);
 130
 131         if (!ops)
 132                 return 0;
 133
 134         if (fwspec->fwnode != d->fwnode || fwspec->param_count != 0)
 135                 return 0;
 136
 137         /* Handle pure domain searches */
 138         if (bus_token == ops->bus_select_token)
 139                 return 1;
 140
 141         return !!(ops->bus_select_mask & busmask);
 142 }
 143 EXPORT_SYMBOL_GPL(msi_lib_irq_domain_select);