arch/powerpc/platforms/pseries/msi.c - kernel/msm-4.9 - Gitiles

 /*
  * 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, return the number of irqs allocated.
 	 * If not, make sure we return a negative error code.
 	 */
 	if (rc == 0)
 		rc = rtas_ret[0];
 	else if (rc > 0)
 		rc = -rc;

 	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;

 	/*
 	 * disabling MSI with the explicit interface also disables MSI-X
 	 */
 	if (rtas_change_msi(pdn, RTAS_CHANGE_MSI_FN, 0) != 0) {
 		/*
 		 * may have failed because explicit interface is not
 		 * present
 		 */
 		if (rtas_change_msi(pdn, RTAS_CHANGE_FN, 0) != 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;

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

 	rtas_disable_msi(pdev);
 }

 static int check_req(struct pci_dev *pdev, int nvec, char *prop_name)
 {
 	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, prop_name, NULL);
 	if (!req_msi) {
 		pr_debug("rtas_msi: No %s on %s\n", prop_name, dn->full_name);
 		return -ENOENT;
 	}

 	if (*req_msi < nvec) {
 		pr_debug("rtas_msi: %s requests < %d MSIs\n", prop_name, nvec);

 		if (*req_msi == 0) /* Be paranoid */
 			return -ENOSPC;

 		return *req_msi;
 	}

 	return 0;
 }

 static int check_req_msi(struct pci_dev *pdev, int nvec)
 {
 	return check_req(pdev, nvec, "ibm,req#msi");
 }

 static int check_req_msix(struct pci_dev *pdev, int nvec)
 {
 	return check_req(pdev, nvec, "ibm,req#msi-x");
 }

 /* Quota calculation */

 static struct device_node *find_pe_total_msi(struct pci_dev *dev, int *total)
 {
 	struct device_node *dn;
 	const u32 *p;

 	dn = of_node_get(pci_device_to_OF_node(dev));
 	while (dn) {
 		p = of_get_property(dn, "ibm,pe-total-#msi", NULL);
 		if (p) {
 			pr_debug("rtas_msi: found prop on dn %s\n",
 				dn->full_name);
 			*total = *p;
 			return dn;
 		}

 		dn = of_get_next_parent(dn);
 	}

 	return NULL;
 }

 static struct device_node *find_pe_dn(struct pci_dev *dev, int *total)
 {
 	struct device_node *dn;
 	struct eeh_dev *edev;

 	/* Found our PE and assume 8 at that point. */

 	dn = pci_device_to_OF_node(dev);
 	if (!dn)
 		return NULL;

 	/* Get the top level device in the PE */
 	edev = of_node_to_eeh_dev(dn);
 	edev = list_first_entry(&edev->pe->edevs, struct eeh_dev, list);
 	dn = eeh_dev_to_of_node(edev);
 	if (!dn)
 		return NULL;

 	/* We actually want the parent */
 	dn = of_get_parent(dn);
 	if (!dn)
 		return NULL;

 	/* Hardcode of 8 for old firmwares */
 	*total = 8;
 	pr_debug("rtas_msi: using PE dn %s\n", dn->full_name);

 	return dn;
 }

 struct msi_counts {
 	struct device_node *requestor;
 	int num_devices;
 	int request;
 	int quota;
 	int spare;
 	int over_quota;
 };

 static void *count_non_bridge_devices(struct device_node *dn, void *data)
 {
 	struct msi_counts *counts = data;
 	const u32 *p;
 	u32 class;

 	pr_debug("rtas_msi: counting %s\n", dn->full_name);

 	p = of_get_property(dn, "class-code", NULL);
 	class = p ? *p : 0;

 	if ((class >> 8) != PCI_CLASS_BRIDGE_PCI)
 		counts->num_devices++;

 	return NULL;
 }

 static void *count_spare_msis(struct device_node *dn, void *data)
 {
 	struct msi_counts *counts = data;
 	const u32 *p;
 	int req;

 	if (dn == counts->requestor)
 		req = counts->request;
 	else {
 		/* We don't know if a driver will try to use MSI or MSI-X,
 		 * so we just have to punt and use the larger of the two. */
 		req = 0;
 		p = of_get_property(dn, "ibm,req#msi", NULL);
 		if (p)
 			req = *p;

 		p = of_get_property(dn, "ibm,req#msi-x", NULL);
 		if (p)
 			req = max(req, (int)*p);
 	}

 	if (req < counts->quota)
 		counts->spare += counts->quota - req;
 	else if (req > counts->quota)
 		counts->over_quota++;

 	return NULL;
 }

 static int msi_quota_for_device(struct pci_dev *dev, int request)
 {
 	struct device_node *pe_dn;
 	struct msi_counts counts;
 	int total;

 	pr_debug("rtas_msi: calc quota for %s, request %d\n", pci_name(dev),
 		  request);

 	pe_dn = find_pe_total_msi(dev, &total);
 	if (!pe_dn)
 		pe_dn = find_pe_dn(dev, &total);

 	if (!pe_dn) {
 		pr_err("rtas_msi: couldn't find PE for %s\n", pci_name(dev));
 		goto out;
 	}

 	pr_debug("rtas_msi: found PE %s\n", pe_dn->full_name);

 	memset(&counts, 0, sizeof(struct msi_counts));

 	/* Work out how many devices we have below this PE */
 	traverse_pci_devices(pe_dn, count_non_bridge_devices, &counts);

 	if (counts.num_devices == 0) {
 		pr_err("rtas_msi: found 0 devices under PE for %s\n",
 			pci_name(dev));
 		goto out;
 	}

 	counts.quota = total / counts.num_devices;
 	if (request <= counts.quota)
 		goto out;

 	/* else, we have some more calculating to do */
 	counts.requestor = pci_device_to_OF_node(dev);
 	counts.request = request;
 	traverse_pci_devices(pe_dn, count_spare_msis, &counts);

 	/* If the quota isn't an integer multiple of the total, we can
 	 * use the remainder as spare MSIs for anyone that wants them. */
 	counts.spare += total % counts.num_devices;

 	/* Divide any spare by the number of over-quota requestors */
 	if (counts.over_quota)
 		counts.quota += counts.spare / counts.over_quota;

 	/* And finally clamp the request to the possibly adjusted quota */
 	request = min(counts.quota, request);

 	pr_debug("rtas_msi: request clamped to quota %d\n", request);
 out:
 	of_node_put(pe_dn);

 	return request;
 }

 static int rtas_msi_check_device(struct pci_dev *pdev, int nvec, int type)
 {
 	int quota, rc;

 	if (type == PCI_CAP_ID_MSIX)
 		rc = check_req_msix(pdev, nvec);
 	else
 		rc = check_req_msi(pdev, nvec);

 	if (rc)
 		return rc;

 	quota = msi_quota_for_device(pdev, nvec);

 	if (quota && quota < nvec)
 		return quota;

 	return 0;
 }

 static int check_msix_entries(struct pci_dev *pdev)
 {
 	struct msi_desc *entry;
 	int expected;

 	/* There's no way for us to express to firmware that we want
 	 * a discontiguous, or non-zero based, range of MSI-X entries.
 	 * So we must reject such requests. */

 	expected = 0;
 	list_for_each_entry(entry, &pdev->msi_list, list) {
 		if (entry->msi_attrib.entry_nr != expected) {
 			pr_debug("rtas_msi: bad MSI-X entries.\n");
 			return -EINVAL;
 		}
 		expected++;
 	}

 	return 0;
 }

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

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

 	if (type == PCI_CAP_ID_MSIX && check_msix_entries(pdev))
 		return -EINVAL;

 	/*
 	 * Firmware currently refuse any non power of two allocation
 	 * so we round up if the quota will allow it.
 	 */
 	if (type == PCI_CAP_ID_MSIX) {
 		int m = roundup_pow_of_two(nvec);
 		int quota = msi_quota_for_device(pdev, m);

 		if (quota >= m)
 			nvec = m;
 	}

 	/*
 	 * 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.
 	 */
 again:
 	if (type == PCI_CAP_ID_MSI) {
 		rc = rtas_change_msi(pdn, RTAS_CHANGE_MSI_FN, nvec);

 		if (rc < 0) {
 			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 != nvec) {
 		if (nvec != nvec_in) {
 			nvec = nvec_in;
 			goto again;
 		}
 		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);
 		irq_set_msi_desc(virq, entry);

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

 	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) && check_req_msix(pdev, 1)) {
 		dev_dbg(&pdev->dev, "rtas_msi: no req#msi/x, 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);
	/*
	* 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, return the number of irqs allocated.
	* If not, make sure we return a negative error code.
	*/
	if (rc == 0)
	rc = rtas_ret[0];
	else if (rc > 0)
	rc = -rc;

	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;

	/*
	* disabling MSI with the explicit interface also disables MSI-X
	*/
	if (rtas_change_msi(pdn, RTAS_CHANGE_MSI_FN, 0) != 0) {
	/*
	* may have failed because explicit interface is not
	* present
	*/
	if (rtas_change_msi(pdn, RTAS_CHANGE_FN, 0) != 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;

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

	rtas_disable_msi(pdev);
	}

	static int check_req(struct pci_dev pdev, int nvec, char prop_name)
	{
	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, prop_name, NULL);
	if (!req_msi) {
	pr_debug("rtas_msi: No %s on %s\n", prop_name, dn->full_name);
	return -ENOENT;
	}

	if (*req_msi < nvec) {
	pr_debug("rtas_msi: %s requests < %d MSIs\n", prop_name, nvec);

	if (req_msi == 0) / Be paranoid */
	return -ENOSPC;

	return *req_msi;
	}

	return 0;
	}

	static int check_req_msi(struct pci_dev *pdev, int nvec)
	{
	return check_req(pdev, nvec, "ibm,req#msi");
	}

	static int check_req_msix(struct pci_dev *pdev, int nvec)
	{
	return check_req(pdev, nvec, "ibm,req#msi-x");
	}

	/* Quota calculation */

	static struct device_node find_pe_total_msi(struct pci_dev dev, int *total)
	{
	struct device_node *dn;
	const u32 *p;

	dn = of_node_get(pci_device_to_OF_node(dev));
	while (dn) {
	p = of_get_property(dn, "ibm,pe-total-#msi", NULL);
	if (p) {
	pr_debug("rtas_msi: found prop on dn %s\n",
	dn->full_name);
	total = p;
	return dn;
	}

	dn = of_get_next_parent(dn);
	}

	return NULL;
	}

	static struct device_node find_pe_dn(struct pci_dev dev, int *total)
	{
	struct device_node *dn;
	struct eeh_dev *edev;

	/* Found our PE and assume 8 at that point. */

	dn = pci_device_to_OF_node(dev);
	if (!dn)
	return NULL;

	/* Get the top level device in the PE */
	edev = of_node_to_eeh_dev(dn);
	edev = list_first_entry(&edev->pe->edevs, struct eeh_dev, list);
	dn = eeh_dev_to_of_node(edev);
	if (!dn)
	return NULL;

	/* We actually want the parent */
	dn = of_get_parent(dn);
	if (!dn)
	return NULL;

	/* Hardcode of 8 for old firmwares */
	*total = 8;
	pr_debug("rtas_msi: using PE dn %s\n", dn->full_name);

	return dn;
	}

	struct msi_counts {
	struct device_node *requestor;
	int num_devices;
	int request;
	int quota;
	int spare;
	int over_quota;
	};

	static void count_non_bridge_devices(struct device_node dn, void *data)
	{
	struct msi_counts *counts = data;
	const u32 *p;
	u32 class;

	pr_debug("rtas_msi: counting %s\n", dn->full_name);

	p = of_get_property(dn, "class-code", NULL);
	class = p ? *p : 0;

	if ((class >> 8) != PCI_CLASS_BRIDGE_PCI)
	counts->num_devices++;

	return NULL;
	}

	static void count_spare_msis(struct device_node dn, void *data)
	{
	struct msi_counts *counts = data;
	const u32 *p;
	int req;

	if (dn == counts->requestor)
	req = counts->request;
	else {
	/* We don't know if a driver will try to use MSI or MSI-X,
	* so we just have to punt and use the larger of the two. */
	req = 0;
	p = of_get_property(dn, "ibm,req#msi", NULL);
	if (p)
	req = *p;

	p = of_get_property(dn, "ibm,req#msi-x", NULL);
	if (p)
	req = max(req, (int)*p);
	}

	if (req < counts->quota)
	counts->spare += counts->quota - req;
	else if (req > counts->quota)
	counts->over_quota++;

	return NULL;
	}

	static int msi_quota_for_device(struct pci_dev *dev, int request)
	{
	struct device_node *pe_dn;
	struct msi_counts counts;
	int total;

	pr_debug("rtas_msi: calc quota for %s, request %d\n", pci_name(dev),
	request);

	pe_dn = find_pe_total_msi(dev, &total);
	if (!pe_dn)
	pe_dn = find_pe_dn(dev, &total);

	if (!pe_dn) {
	pr_err("rtas_msi: couldn't find PE for %s\n", pci_name(dev));
	goto out;
	}

	pr_debug("rtas_msi: found PE %s\n", pe_dn->full_name);

	memset(&counts, 0, sizeof(struct msi_counts));

	/* Work out how many devices we have below this PE */
	traverse_pci_devices(pe_dn, count_non_bridge_devices, &counts);

	if (counts.num_devices == 0) {
	pr_err("rtas_msi: found 0 devices under PE for %s\n",
	pci_name(dev));
	goto out;
	}

	counts.quota = total / counts.num_devices;
	if (request <= counts.quota)
	goto out;

	/* else, we have some more calculating to do */
	counts.requestor = pci_device_to_OF_node(dev);
	counts.request = request;
	traverse_pci_devices(pe_dn, count_spare_msis, &counts);

	/* If the quota isn't an integer multiple of the total, we can
	* use the remainder as spare MSIs for anyone that wants them. */
	counts.spare += total % counts.num_devices;

	/* Divide any spare by the number of over-quota requestors */
	if (counts.over_quota)
	counts.quota += counts.spare / counts.over_quota;

	/* And finally clamp the request to the possibly adjusted quota */
	request = min(counts.quota, request);

	pr_debug("rtas_msi: request clamped to quota %d\n", request);
	out:
	of_node_put(pe_dn);

	return request;
	}

	static int rtas_msi_check_device(struct pci_dev *pdev, int nvec, int type)
	{
	int quota, rc;

	if (type == PCI_CAP_ID_MSIX)
	rc = check_req_msix(pdev, nvec);
	else
	rc = check_req_msi(pdev, nvec);

	if (rc)
	return rc;

	quota = msi_quota_for_device(pdev, nvec);

	if (quota && quota < nvec)
	return quota;

	return 0;
	}

	static int check_msix_entries(struct pci_dev *pdev)
	{
	struct msi_desc *entry;
	int expected;

	/* There's no way for us to express to firmware that we want
	* a discontiguous, or non-zero based, range of MSI-X entries.
	* So we must reject such requests. */

	expected = 0;
	list_for_each_entry(entry, &pdev->msi_list, list) {
	if (entry->msi_attrib.entry_nr != expected) {
	pr_debug("rtas_msi: bad MSI-X entries.\n");
	return -EINVAL;
	}
	expected++;
	}

	return 0;
	}

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

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

	if (type == PCI_CAP_ID_MSIX && check_msix_entries(pdev))
	return -EINVAL;

	/*
	* Firmware currently refuse any non power of two allocation
	* so we round up if the quota will allow it.
	*/
	if (type == PCI_CAP_ID_MSIX) {
	int m = roundup_pow_of_two(nvec);
	int quota = msi_quota_for_device(pdev, m);

	if (quota >= m)
	nvec = m;
	}

	/*
	* 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.
	*/
	again:
	if (type == PCI_CAP_ID_MSI) {
	rc = rtas_change_msi(pdn, RTAS_CHANGE_MSI_FN, nvec);

	if (rc < 0) {
	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 != nvec) {
	if (nvec != nvec_in) {
	nvec = nvec_in;
	goto again;
	}
	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);
	irq_set_msi_desc(virq, entry);

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

	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) && check_req_msix(pdev, 1)) {
	dev_dbg(&pdev->dev, "rtas_msi: no req#msi/x, 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);