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Commit c09fcc4b authored by Marc Zyngier's avatar Marc Zyngier Committed by Thomas Gleixner
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drivers/base: Add MSI domain support for non-PCI devices 



With the msi_list and the msi_domain properties now being at the
generic device level, it is starting to be relatively easy to offer
a generic way of providing non-PCI MSIs.

The two major hurdles with this idea are:

- Lack of global ID that identifies a device: this is worked around by
  having a global ID allocator for each device that gets enrolled in
  the platform MSI subsystem

- Lack of standard way to write the message in the generating device.
  This is solved by mandating driver code to provide a write_msg
  callback, so that everyone can have their own square wheel

Apart from that, the API is fairly straightforward:

- platform_msi_create_irq_domain creates an MSI domain that gets
  tagged with DOMAIN_BUS_PLATFORM_MSI

- platform_msi_domain_alloc_irqs allocate MSIs for a given device,
  populating the msi_list

- platform_msi_domain_free_irqs does what is written on the tin

[ tglx: Created a seperate struct platform_msi_desc and added
  	kerneldoc entries ]

Signed-off-by: default avatarMarc Zyngier <marc.zyngier@arm.com>
Cc: <linux-arm-kernel@lists.infradead.org>
Cc: Yijing Wang <wangyijing@huawei.com>
Cc: Ma Jun <majun258@huawei.com>
Cc: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Cc: Duc Dang <dhdang@apm.com>
Cc: Hanjun Guo <hanjun.guo@linaro.org>
Cc: Bjorn Helgaas <bhelgaas@google.com>
Cc: Jiang Liu <jiang.liu@linux.intel.com>
Cc: Jason Cooper <jason@lakedaemon.net>
Link: http://lkml.kernel.org/r/1438091186-10244-10-git-send-email-marc.zyngier@arm.com


Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
parent c706c239

drivers/base/Makefile

+1 −0
Original line number Diff line number Diff line
@@ -22,6 +22,7 @@ obj-$(CONFIG_REGMAP) += regmap/ 
obj-$(CONFIG_SOC_BUS) += soc.o

obj-$(CONFIG_PINCTRL) += pinctrl.o

obj-$(CONFIG_DEV_COREDUMP) += devcoredump.o

obj-$(CONFIG_GENERIC_MSI_IRQ_DOMAIN) += platform-msi.o



ccflags-$(CONFIG_DEBUG_DRIVER) := -DDEBUG

drivers/base/platform-msi.c

0 → 100644
+282 −0
Original line number Diff line number Diff line 
/*

 * MSI framework for platform devices

 *

 * Copyright (C) 2015 ARM Limited, All Rights Reserved.

 * Author: Marc Zyngier <marc.zyngier@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.

 *

 * This program is distributed in the hope that it will be useful,

 * but WITHOUT ANY WARRANTY; without even the implied warranty of

 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

 * GNU General Public License for more details.

 *

 * You should have received a copy of the GNU General Public License

 * along with this program.  If not, see <http://www.gnu.org/licenses/>.

 */



#include <linux/device.h>

#include <linux/idr.h>

#include <linux/irq.h>

#include <linux/irqdomain.h>

#include <linux/msi.h>

#include <linux/slab.h>



#define DEV_ID_SHIFT	24



/*

 * Internal data structure containing a (made up, but unique) devid

 * and the callback to write the MSI message.

 */

struct platform_msi_priv_data {

	irq_write_msi_msg_t	write_msg;

	int			devid;

};



/* The devid allocator */

static DEFINE_IDA(platform_msi_devid_ida);



#ifdef GENERIC_MSI_DOMAIN_OPS

/*

 * Convert an msi_desc to a globaly unique identifier (per-device

 * devid + msi_desc position in the msi_list).

 */

static irq_hw_number_t platform_msi_calc_hwirq(struct msi_desc *desc)

{

	u32 devid;



	devid = desc->platform.msi_priv_data->devid;



	return (devid << (32 - DEV_ID_SHIFT)) | desc->platform.msi_index;

}



static void platform_msi_set_desc(msi_alloc_info_t *arg, struct msi_desc *desc)

{

	arg->desc = desc;

	arg->hwirq = platform_msi_calc_hwirq(desc);

}



static int platform_msi_init(struct irq_domain *domain,

			     struct msi_domain_info *info,

			     unsigned int virq, irq_hw_number_t hwirq,

			     msi_alloc_info_t *arg)

{

	struct irq_data *data;



	irq_domain_set_hwirq_and_chip(domain, virq, hwirq,

				      info->chip, info->chip_data);



	/*

	 * Save the MSI descriptor in handler_data so that the

	 * irq_write_msi_msg callback can retrieve it (and the

	 * associated device).

	 */

	data = irq_domain_get_irq_data(domain, virq);

	data->handler_data = arg->desc;



	return 0;

}

#else

#define platform_msi_set_desc		NULL

#define platform_msi_init		NULL

#endif



static void platform_msi_update_dom_ops(struct msi_domain_info *info)

{

	struct msi_domain_ops *ops = info->ops;



	BUG_ON(!ops);



	if (ops->msi_init == NULL)

		ops->msi_init = platform_msi_init;

	if (ops->set_desc == NULL)

		ops->set_desc = platform_msi_set_desc;

}



static void platform_msi_write_msg(struct irq_data *data, struct msi_msg *msg)

{

	struct msi_desc *desc = irq_data_get_irq_handler_data(data);

	struct platform_msi_priv_data *priv_data;



	priv_data = desc->platform.msi_priv_data;



	priv_data->write_msg(desc, msg);

}



static void platform_msi_update_chip_ops(struct msi_domain_info *info)

{

	struct irq_chip *chip = info->chip;



	BUG_ON(!chip);

	if (!chip->irq_mask)

		chip->irq_mask = irq_chip_mask_parent;

	if (!chip->irq_unmask)

		chip->irq_unmask = irq_chip_unmask_parent;

	if (!chip->irq_eoi)

		chip->irq_eoi = irq_chip_eoi_parent;

	if (!chip->irq_set_affinity)

		chip->irq_set_affinity = msi_domain_set_affinity;

	if (!chip->irq_write_msi_msg)

		chip->irq_write_msi_msg = platform_msi_write_msg;

}



static void platform_msi_free_descs(struct device *dev)

{

	struct msi_desc *desc, *tmp;



	list_for_each_entry_safe(desc, tmp, dev_to_msi_list(dev), list) {

		list_del(&desc->list);

		free_msi_entry(desc);

	}

}



static int platform_msi_alloc_descs(struct device *dev, int nvec,

				    struct platform_msi_priv_data *data)



{

	int i;



	for (i = 0; i < nvec; i++) {

		struct msi_desc *desc;



		desc = alloc_msi_entry(dev);

		if (!desc)

			break;



		desc->platform.msi_priv_data = data;

		desc->platform.msi_index = i;

		desc->nvec_used = 1;



		list_add_tail(&desc->list, dev_to_msi_list(dev));

	}



	if (i != nvec) {

		/* Clean up the mess */

		platform_msi_free_descs(dev);



		return -ENOMEM;

	}



	return 0;

}



/**

 * platform_msi_create_irq_domain - Create a platform MSI interrupt domain

 * @np:		Optional device-tree node of the interrupt controller

 * @info:	MSI domain info

 * @parent:	Parent irq domain

 *

 * Updates the domain and chip ops and creates a platform MSI

 * interrupt domain.

 *

 * Returns:

 * A domain pointer or NULL in case of failure.

 */

struct irq_domain *platform_msi_create_irq_domain(struct device_node *np,

						  struct msi_domain_info *info,

						  struct irq_domain *parent)

{

	struct irq_domain *domain;



	if (info->flags & MSI_FLAG_USE_DEF_DOM_OPS)

		platform_msi_update_dom_ops(info);

	if (info->flags & MSI_FLAG_USE_DEF_CHIP_OPS)

		platform_msi_update_chip_ops(info);



	domain = msi_create_irq_domain(np, info, parent);

	if (domain)

		domain->bus_token = DOMAIN_BUS_PLATFORM_MSI;



	return domain;

}



/**

 * platform_msi_domain_alloc_irqs - Allocate MSI interrupts for @dev

 * @dev:		The device for which to allocate interrupts

 * @nvec:		The number of interrupts to allocate

 * @write_msi_msg:	Callback to write an interrupt message for @dev

 *

 * Returns:

 * Zero for success, or an error code in case of failure

 */

int platform_msi_domain_alloc_irqs(struct device *dev, unsigned int nvec,

				   irq_write_msi_msg_t write_msi_msg)

{

	struct platform_msi_priv_data *priv_data;

	int err;



	/*

	 * Limit the number of interrupts to 256 per device. Should we

	 * need to bump this up, DEV_ID_SHIFT should be adjusted

	 * accordingly (which would impact the max number of MSI

	 * capable devices).

	 */

	if (!dev->msi_domain || !write_msi_msg || !nvec ||

	    nvec > (1 << (32 - DEV_ID_SHIFT)))

		return -EINVAL;



	if (dev->msi_domain->bus_token != DOMAIN_BUS_PLATFORM_MSI) {

		dev_err(dev, "Incompatible msi_domain, giving up\n");

		return -EINVAL;

	}



	/* Already had a helping of MSI? Greed... */

	if (!list_empty(dev_to_msi_list(dev)))

		return -EBUSY;



	priv_data = kzalloc(sizeof(*priv_data), GFP_KERNEL);

	if (!priv_data)

		return -ENOMEM;



	priv_data->devid = ida_simple_get(&platform_msi_devid_ida,

					  0, 1 << DEV_ID_SHIFT, GFP_KERNEL);

	if (priv_data->devid < 0) {

		err = priv_data->devid;

		goto out_free_data;

	}



	priv_data->write_msg = write_msi_msg;



	err = platform_msi_alloc_descs(dev, nvec, priv_data);

	if (err)

		goto out_free_id;



	err = msi_domain_alloc_irqs(dev->msi_domain, dev, nvec);

	if (err)

		goto out_free_desc;



	return 0;



out_free_desc:

	platform_msi_free_descs(dev);

out_free_id:

	ida_simple_remove(&platform_msi_devid_ida, priv_data->devid);

out_free_data:

	kfree(priv_data);



	return err;

}



/**

 * platform_msi_domain_free_irqs - Free MSI interrupts for @dev

 * @dev:	The device for which to free interrupts

 */

void platform_msi_domain_free_irqs(struct device *dev)

{

	struct msi_desc *desc;



	desc = first_msi_entry(dev);

	if (desc) {

		struct platform_msi_priv_data *data;



		data = desc->platform.msi_priv_data;



		ida_simple_remove(&platform_msi_devid_ida, data->devid);

		kfree(data);

	}



	msi_domain_free_irqs(dev->msi_domain, dev);

	platform_msi_free_descs(dev);

}

include/linux/msi.h

+22 −0
Original line number Diff line number Diff line
@@ -15,9 +15,23 @@ extern int pci_msi_ignore_mask; 
struct irq_data;

struct msi_desc;

struct pci_dev;

struct platform_msi_priv_data;

void __get_cached_msi_msg(struct msi_desc *entry, struct msi_msg *msg);

void get_cached_msi_msg(unsigned int irq, struct msi_msg *msg);



typedef void (*irq_write_msi_msg_t)(struct msi_desc *desc,

				    struct msi_msg *msg);



/**

 * platform_msi_desc - Platform device specific msi descriptor data

 * @msi_priv_data:	Pointer to platform private data

 * @msi_index:		The index of the MSI descriptor for multi MSI

 */

struct platform_msi_desc {

	struct platform_msi_priv_data	*msi_priv_data;

	u16				msi_index;

};



/**

 * struct msi_desc - Descriptor structure for MSI based interrupts

 * @list:	List head for management
@@ -36,6 +50,7 @@ void get_cached_msi_msg(unsigned int irq, struct msi_msg *msg); 
 * @default_irq:[PCI MSI/X] The default pre-assigned non-MSI irq

 * @mask_pos:	[PCI MSI]   Mask register position

 * @mask_base:	[PCI MSI-X] Mask register base address

 * @platform:	[platform]  Platform device specific msi descriptor data

 */

struct msi_desc {

	/* Shared device/bus type independent data */
@@ -71,6 +86,7 @@ struct msi_desc { 
		 * anonymous for now as it would require an immediate

		 * tree wide cleanup.

		 */

		struct platform_msi_desc platform;

	};

};
@@ -257,6 +273,12 @@ int msi_domain_alloc_irqs(struct irq_domain *domain, struct device *dev, 
void msi_domain_free_irqs(struct irq_domain *domain, struct device *dev);

struct msi_domain_info *msi_get_domain_info(struct irq_domain *domain);



struct irq_domain *platform_msi_create_irq_domain(struct device_node *np,

						  struct msi_domain_info *info,

						  struct irq_domain *parent);

int platform_msi_domain_alloc_irqs(struct device *dev, unsigned int nvec,

				   irq_write_msi_msg_t write_msi_msg);

void platform_msi_domain_free_irqs(struct device *dev);

#endif /* CONFIG_GENERIC_MSI_IRQ_DOMAIN */



#ifdef CONFIG_PCI_MSI_IRQ_DOMAIN