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msi.c

/*
 * Copyright 2006 Jake Moilanen <moilanen@austin.ibm.com>, IBM Corp.
 * Copyright 2006-2007 Michael Ellerman, IBM Corp.
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; version 2 of the
 * License.
 *
 */

#include <linux/device.h>
#include <linux/irq.h>
#include <linux/msi.h>

#include <asm/rtas.h>
#include <asm/hw_irq.h>
#include <asm/ppc-pci.h>

static int query_token, change_token;

#define RTAS_QUERY_FN         0
#define RTAS_CHANGE_FN        1
#define RTAS_RESET_FN         2
#define RTAS_CHANGE_MSI_FN    3
#define RTAS_CHANGE_MSIX_FN   4

static struct pci_dn *get_pdn(struct pci_dev *pdev)
{
      struct device_node *dn;
      struct pci_dn *pdn;

      dn = pci_device_to_OF_node(pdev);
      if (!dn) {
            dev_dbg(&pdev->dev, "rtas_msi: No OF device node\n");
            return NULL;
      }

      pdn = PCI_DN(dn);
      if (!pdn) {
            dev_dbg(&pdev->dev, "rtas_msi: No PCI DN\n");
            return NULL;
      }

      return pdn;
}

/* RTAS Helpers */

static int rtas_change_msi(struct pci_dn *pdn, u32 func, u32 num_irqs)
{
      u32 addr, seq_num, rtas_ret[3];
      unsigned long buid;
      int rc;

      addr = rtas_config_addr(pdn->busno, pdn->devfn, 0);
      buid = pdn->phb->buid;

      seq_num = 1;
      do {
            if (func == RTAS_CHANGE_MSI_FN || func == RTAS_CHANGE_MSIX_FN)
                  rc = rtas_call(change_token, 6, 4, rtas_ret, addr,
                              BUID_HI(buid), BUID_LO(buid),
                              func, num_irqs, seq_num);
            else
                  rc = rtas_call(change_token, 6, 3, rtas_ret, addr,
                              BUID_HI(buid), BUID_LO(buid),
                              func, num_irqs, seq_num);

            seq_num = rtas_ret[1];
      } while (rtas_busy_delay(rc));

      /*
       * If the RTAS call succeeded, check the number of irqs is actually
       * what we asked for. If not, return an error.
       */
      if (rc == 0 && rtas_ret[0] != num_irqs)
            rc = -ENOSPC;

      pr_debug("rtas_msi: ibm,change_msi(func=%d,num=%d), got %d rc = %d\n",
             func, num_irqs, rtas_ret[0], rc);

      return rc;
}

static void rtas_disable_msi(struct pci_dev *pdev)
{
      struct pci_dn *pdn;

      pdn = get_pdn(pdev);
      if (!pdn)
            return;

      if (rtas_change_msi(pdn, RTAS_CHANGE_FN, 0))
            pr_debug("rtas_msi: Setting MSIs to 0 failed!\n");
}

static int rtas_query_irq_number(struct pci_dn *pdn, int offset)
{
      u32 addr, rtas_ret[2];
      unsigned long buid;
      int rc;

      addr = rtas_config_addr(pdn->busno, pdn->devfn, 0);
      buid = pdn->phb->buid;

      do {
            rc = rtas_call(query_token, 4, 3, rtas_ret, addr,
                         BUID_HI(buid), BUID_LO(buid), offset);
      } while (rtas_busy_delay(rc));

      if (rc) {
            pr_debug("rtas_msi: error (%d) querying source number\n", rc);
            return rc;
      }

      return rtas_ret[0];
}

static void rtas_teardown_msi_irqs(struct pci_dev *pdev)
{
      struct msi_desc *entry;

      list_for_each_entry(entry, &pdev->msi_list, list) {
            if (entry->irq == NO_IRQ)
                  continue;

            set_irq_msi(entry->irq, NULL);
            irq_dispose_mapping(entry->irq);
      }

      rtas_disable_msi(pdev);
}

static int check_req_msi(struct pci_dev *pdev, int nvec)
{
      struct device_node *dn;
      struct pci_dn *pdn;
      const u32 *req_msi;

      pdn = get_pdn(pdev);
      if (!pdn)
            return -ENODEV;

      dn = pdn->node;

      req_msi = of_get_property(dn, "ibm,req#msi", NULL);
      if (!req_msi) {
            pr_debug("rtas_msi: No ibm,req#msi on %s\n", dn->full_name);
            return -ENOENT;
      }

      if (*req_msi < nvec) {
            pr_debug("rtas_msi: ibm,req#msi requests < %d MSIs\n", nvec);
            return -ENOSPC;
      }

      return 0;
}

static int rtas_msi_check_device(struct pci_dev *pdev, int nvec, int type)
{
      if (type == PCI_CAP_ID_MSIX)
            pr_debug("rtas_msi: MSI-X untested, trying anyway.\n");

      return check_req_msi(pdev, nvec);
}

static int rtas_setup_msi_irqs(struct pci_dev *pdev, int nvec, int type)
{
      struct pci_dn *pdn;
      int hwirq, virq, i, rc;
      struct msi_desc *entry;
      struct msi_msg msg;

      pdn = get_pdn(pdev);
      if (!pdn)
            return -ENODEV;

      /*
       * Try the new more explicit firmware interface, if that fails fall
       * back to the old interface. The old interface is known to never
       * return MSI-Xs.
       */
      if (type == PCI_CAP_ID_MSI) {
            rc = rtas_change_msi(pdn, RTAS_CHANGE_MSI_FN, nvec);

            if (rc) {
                  pr_debug("rtas_msi: trying the old firmware call.\n");
                  rc = rtas_change_msi(pdn, RTAS_CHANGE_FN, nvec);
            }
      } else
            rc = rtas_change_msi(pdn, RTAS_CHANGE_MSIX_FN, nvec);

      if (rc) {
            pr_debug("rtas_msi: rtas_change_msi() failed\n");
            return rc;
      }

      i = 0;
      list_for_each_entry(entry, &pdev->msi_list, list) {
            hwirq = rtas_query_irq_number(pdn, i);
            if (hwirq < 0) {
                  pr_debug("rtas_msi: error (%d) getting hwirq\n", rc);
                  return hwirq;
            }

            virq = irq_create_mapping(NULL, hwirq);

            if (virq == NO_IRQ) {
                  pr_debug("rtas_msi: Failed mapping hwirq %d\n", hwirq);
                  return -ENOSPC;
            }

            dev_dbg(&pdev->dev, "rtas_msi: allocated virq %d\n", virq);
            set_irq_msi(virq, entry);

            /* Read config space back so we can restore after reset */
            read_msi_msg(virq, &msg);
            entry->msg = msg;

            unmask_msi_irq(virq);
      }

      return 0;
}

static void rtas_msi_pci_irq_fixup(struct pci_dev *pdev)
{
      /* No LSI -> leave MSIs (if any) configured */
      if (pdev->irq == NO_IRQ) {
            dev_dbg(&pdev->dev, "rtas_msi: no LSI, nothing to do.\n");
            return;
      }

      /* No MSI -> MSIs can't have been assigned by fw, leave LSI */
      if (check_req_msi(pdev, 1)) {
            dev_dbg(&pdev->dev, "rtas_msi: no req#msi, nothing to do.\n");
            return;
      }

      dev_dbg(&pdev->dev, "rtas_msi: disabling existing MSI.\n");
      rtas_disable_msi(pdev);
}

static int rtas_msi_init(void)
{
      query_token  = rtas_token("ibm,query-interrupt-source-number");
      change_token = rtas_token("ibm,change-msi");

      if ((query_token == RTAS_UNKNOWN_SERVICE) ||
                  (change_token == RTAS_UNKNOWN_SERVICE)) {
            pr_debug("rtas_msi: no RTAS tokens, no MSI support.\n");
            return -1;
      }

      pr_debug("rtas_msi: Registering RTAS MSI callbacks.\n");

      WARN_ON(ppc_md.setup_msi_irqs);
      ppc_md.setup_msi_irqs = rtas_setup_msi_irqs;
      ppc_md.teardown_msi_irqs = rtas_teardown_msi_irqs;
      ppc_md.msi_check_device = rtas_msi_check_device;

      WARN_ON(ppc_md.pci_irq_fixup);
      ppc_md.pci_irq_fixup = rtas_msi_pci_irq_fixup;

      return 0;
}
arch_initcall(rtas_msi_init);

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