drivers/base/platform-msi.c

   1 /*
   2  * MSI framework for platform devices
   3  *
   4  * Copyright (C) 2015 ARM Limited, All Rights Reserved.
   5  * Author: Marc Zyngier <marc.zyngier@arm.com>
   6  *
   7  * This program is free software; you can redistribute it and/or modify
   8  * it under the terms of the GNU General Public License version 2 as
   9  * published by the Free Software Foundation.
  10  *
  11  * This program is distributed in the hope that it will be useful,
  12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14  * GNU General Public License for more details.
  15  *
  16  * You should have received a copy of the GNU General Public License
  17  * along with this program.  If not, see <http://www.gnu.org/licenses/>.
  18  */
  19
  20 #include <linux/device.h>
  21 #include <linux/idr.h>
  22 #include <linux/irq.h>
  23 #include <linux/irqdomain.h>
  24 #include <linux/msi.h>
  25 #include <linux/slab.h>
  26
  27 #define DEV_ID_SHIFT    24
  28
  29 /*
  30  * Internal data structure containing a (made up, but unique) devid
  31  * and the callback to write the MSI message.
  32  */
  33 struct platform_msi_priv_data {
  34         irq_write_msi_msg_t     write_msg;
  35         int                     devid;
  36 };
  37
  38 /* The devid allocator */
  39 static DEFINE_IDA(platform_msi_devid_ida);
  40
  41 #ifdef GENERIC_MSI_DOMAIN_OPS
  42 /*
  43  * Convert an msi_desc to a globaly unique identifier (per-device
  44  * devid + msi_desc position in the msi_list).
  45  */
  46 static irq_hw_number_t platform_msi_calc_hwirq(struct msi_desc *desc)
  47 {
  48         u32 devid;
  49
  50         devid = desc->platform.msi_priv_data->devid;
  51
  52         return (devid << (32 - DEV_ID_SHIFT)) | desc->platform.msi_index;
  53 }
  54
  55 static void platform_msi_set_desc(msi_alloc_info_t *arg, struct msi_desc *desc)
  56 {
  57         arg->desc = desc;
  58         arg->hwirq = platform_msi_calc_hwirq(desc);
  59 }
  60
  61 static int platform_msi_init(struct irq_domain *domain,
  62                              struct msi_domain_info *info,
  63                              unsigned int virq, irq_hw_number_t hwirq,
  64                              msi_alloc_info_t *arg)
  65 {
  66         return irq_domain_set_hwirq_and_chip(domain, virq, hwirq,
  67                                              info->chip, info->chip_data);
  68 }
  69 #else
  70 #define platform_msi_set_desc           NULL
  71 #define platform_msi_init               NULL
  72 #endif
  73
  74 static void platform_msi_update_dom_ops(struct msi_domain_info *info)
  75 {
  76         struct msi_domain_ops *ops = info->ops;
  77
  78         BUG_ON(!ops);
  79
  80         if (ops->msi_init == NULL)
  81                 ops->msi_init = platform_msi_init;
  82         if (ops->set_desc == NULL)
  83                 ops->set_desc = platform_msi_set_desc;
  84 }
  85
  86 static void platform_msi_write_msg(struct irq_data *data, struct msi_msg *msg)
  87 {
  88         struct msi_desc *desc = irq_data_get_msi_desc(data);
  89         struct platform_msi_priv_data *priv_data;
  90
  91         priv_data = desc->platform.msi_priv_data;
  92
  93         priv_data->write_msg(desc, msg);
  94 }
  95
  96 static void platform_msi_update_chip_ops(struct msi_domain_info *info)
  97 {
  98         struct irq_chip *chip = info->chip;
  99
 100         BUG_ON(!chip);
 101         if (!chip->irq_mask)
 102                 chip->irq_mask = irq_chip_mask_parent;
 103         if (!chip->irq_unmask)
 104                 chip->irq_unmask = irq_chip_unmask_parent;
 105         if (!chip->irq_eoi)
 106                 chip->irq_eoi = irq_chip_eoi_parent;
 107         if (!chip->irq_set_affinity)
 108                 chip->irq_set_affinity = msi_domain_set_affinity;
 109         if (!chip->irq_write_msi_msg)
 110                 chip->irq_write_msi_msg = platform_msi_write_msg;
 111 }
 112
 113 static void platform_msi_free_descs(struct device *dev)
 114 {
 115         struct msi_desc *desc, *tmp;
 116
 117         list_for_each_entry_safe(desc, tmp, dev_to_msi_list(dev), list) {
 118                 list_del(&desc->list);
 119                 free_msi_entry(desc);
 120         }
 121 }
 122
 123 static int platform_msi_alloc_descs(struct device *dev, int nvec,
 124                                     struct platform_msi_priv_data *data)
 125
 126 {
 127         int i;
 128
 129         for (i = 0; i < nvec; i++) {
 130                 struct msi_desc *desc;
 131
 132                 desc = alloc_msi_entry(dev);
 133                 if (!desc)
 134                         break;
 135
 136                 desc->platform.msi_priv_data = data;
 137                 desc->platform.msi_index = i;
 138                 desc->nvec_used = 1;
 139
 140                 list_add_tail(&desc->list, dev_to_msi_list(dev));
 141         }
 142
 143         if (i != nvec) {
 144                 /* Clean up the mess */
 145                 platform_msi_free_descs(dev);
 146
 147                 return -ENOMEM;
 148         }
 149
 150         return 0;
 151 }
 152
 153 /**
 154  * platform_msi_create_irq_domain - Create a platform MSI interrupt domain
 155  * @np:         Optional device-tree node of the interrupt controller
 156  * @info:       MSI domain info
 157  * @parent:     Parent irq domain
 158  *
 159  * Updates the domain and chip ops and creates a platform MSI
 160  * interrupt domain.
 161  *
 162  * Returns:
 163  * A domain pointer or NULL in case of failure.
 164  */
 165 struct irq_domain *platform_msi_create_irq_domain(struct device_node *np,
 166                                                   struct msi_domain_info *info,
 167                                                   struct irq_domain *parent)
 168 {
 169         struct irq_domain *domain;
 170
 171         if (info->flags & MSI_FLAG_USE_DEF_DOM_OPS)
 172                 platform_msi_update_dom_ops(info);
 173         if (info->flags & MSI_FLAG_USE_DEF_CHIP_OPS)
 174                 platform_msi_update_chip_ops(info);
 175
 176         domain = msi_create_irq_domain(np, info, parent);
 177         if (domain)
 178                 domain->bus_token = DOMAIN_BUS_PLATFORM_MSI;
 179
 180         return domain;
 181 }
 182
 183 /**
 184  * platform_msi_domain_alloc_irqs - Allocate MSI interrupts for @dev
 185  * @dev:                The device for which to allocate interrupts
 186  * @nvec:               The number of interrupts to allocate
 187  * @write_msi_msg:      Callback to write an interrupt message for @dev
 188  *
 189  * Returns:
 190  * Zero for success, or an error code in case of failure
 191  */
 192 int platform_msi_domain_alloc_irqs(struct device *dev, unsigned int nvec,
 193                                    irq_write_msi_msg_t write_msi_msg)
 194 {
 195         struct platform_msi_priv_data *priv_data;
 196         int err;
 197
 198         /*
 199          * Limit the number of interrupts to 256 per device. Should we
 200          * need to bump this up, DEV_ID_SHIFT should be adjusted
 201          * accordingly (which would impact the max number of MSI
 202          * capable devices).
 203          */
 204         if (!dev->msi_domain || !write_msi_msg || !nvec ||
 205             nvec > (1 << (32 - DEV_ID_SHIFT)))
 206                 return -EINVAL;
 207
 208         if (dev->msi_domain->bus_token != DOMAIN_BUS_PLATFORM_MSI) {
 209                 dev_err(dev, "Incompatible msi_domain, giving up\n");
 210                 return -EINVAL;
 211         }
 212
 213         /* Already had a helping of MSI? Greed... */
 214         if (!list_empty(dev_to_msi_list(dev)))
 215                 return -EBUSY;
 216
 217         priv_data = kzalloc(sizeof(*priv_data), GFP_KERNEL);
 218         if (!priv_data)
 219                 return -ENOMEM;
 220
 221         priv_data->devid = ida_simple_get(&platform_msi_devid_ida,
 222                                           0, 1 << DEV_ID_SHIFT, GFP_KERNEL);
 223         if (priv_data->devid < 0) {
 224                 err = priv_data->devid;
 225                 goto out_free_data;
 226         }
 227
 228         priv_data->write_msg = write_msi_msg;
 229
 230         err = platform_msi_alloc_descs(dev, nvec, priv_data);
 231         if (err)
 232                 goto out_free_id;
 233
 234         err = msi_domain_alloc_irqs(dev->msi_domain, dev, nvec);
 235         if (err)
 236                 goto out_free_desc;
 237
 238         return 0;
 239
 240 out_free_desc:
 241         platform_msi_free_descs(dev);
 242 out_free_id:
 243         ida_simple_remove(&platform_msi_devid_ida, priv_data->devid);
 244 out_free_data:
 245         kfree(priv_data);
 246
 247         return err;
 248 }
 249
 250 /**
 251  * platform_msi_domain_free_irqs - Free MSI interrupts for @dev
 252  * @dev:        The device for which to free interrupts
 253  */
 254 void platform_msi_domain_free_irqs(struct device *dev)
 255 {
 256         struct msi_desc *desc;
 257
 258         desc = first_msi_entry(dev);
 259         if (desc) {
 260                 struct platform_msi_priv_data *data;
 261
 262                 data = desc->platform.msi_priv_data;
 263
 264                 ida_simple_remove(&platform_msi_devid_ida, data->devid);
 265                 kfree(data);
 266         }
 267
 268         msi_domain_free_irqs(dev->msi_domain, dev);
 269         platform_msi_free_descs(dev);
 270 }