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 Signed-off-by: Marc Zyngier <marc.zyngier@xxxxxxx> --- drivers/base/Makefile | 1 + drivers/base/platform-msi.c | 282 ++++++++++++++++++++++++++++++++++++++++++++ include/linux/msi.h | 15 +++ 3 files changed, 298 insertions(+) create mode 100644 drivers/base/platform-msi.c diff --git a/drivers/base/Makefile b/drivers/base/Makefile index 527d291..6b2a84e 100644 --- a/drivers/base/Makefile +++ b/drivers/base/Makefile @@ -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 diff --git a/drivers/base/platform-msi.c b/drivers/base/platform-msi.c new file mode 100644 index 0000000..e35be99 --- /dev/null +++ b/drivers/base/platform-msi.c @@ -0,0 +1,282 @@ +/* + * MSI framework for platform devices + * + * Copyright (C) 2015 ARM Limited, All Rights Reserved. + * Author: Marc Zyngier <marc.zyngier@xxxxxxx> + * + * 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->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->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); +} diff --git a/include/linux/msi.h b/include/linux/msi.h index c10ec56..b55cf63 100644 --- a/include/linux/msi.h +++ b/include/linux/msi.h @@ -18,6 +18,11 @@ struct pci_dev; 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); + +struct platform_msi_priv_data; + struct msi_desc { struct list_head list; unsigned int irq; @@ -42,6 +47,10 @@ struct msi_desc { void __iomem *mask_base; }; }; + struct { + struct platform_msi_priv_data *platform_msi_priv_data; + u16 msi_index; + }; }; }; @@ -228,6 +237,12 @@ 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 -- 2.1.4 -- To unsubscribe from this list: send the line "unsubscribe linux-pci" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
