drivers/irqchip/irq-crossbar.c

   1 /*
   2  *  drivers/irqchip/irq-crossbar.c
   3  *
   4  *  Copyright (C) 2013 Texas Instruments Incorporated - http://www.ti.com
   5  *  Author: Sricharan R <r.sricharan@ti.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  */
  12 #include <linux/err.h>
  13 #include <linux/io.h>
  14 #include <linux/irqchip.h>
  15 #include <linux/irqdomain.h>
  16 #include <linux/of_address.h>
  17 #include <linux/of_irq.h>
  18 #include <linux/slab.h>
  19
  20 #define IRQ_FREE        -1
  21 #define IRQ_RESERVED    -2
  22 #define IRQ_SKIP        -3
  23 #define GIC_IRQ_START   32
  24
  25 /**
  26  * struct crossbar_device - crossbar device description
  27  * @lock: spinlock serializing access to @irq_map
  28  * @int_max: maximum number of supported interrupts
  29  * @safe_map: safe default value to initialize the crossbar
  30  * @max_crossbar_sources: Maximum number of crossbar sources
  31  * @irq_map: array of interrupts to crossbar number mapping
  32  * @crossbar_base: crossbar base address
  33  * @register_offsets: offsets for each irq number
  34  * @write: register write function pointer
  35  */
  36 struct crossbar_device {
  37         raw_spinlock_t lock;
  38         uint int_max;
  39         uint safe_map;
  40         uint max_crossbar_sources;
  41         uint *irq_map;
  42         void __iomem *crossbar_base;
  43         int *register_offsets;
  44         void (*write)(int, int);
  45 };
  46
  47 static struct crossbar_device *cb;
  48
  49 static void crossbar_writel(int irq_no, int cb_no)
  50 {
  51         writel(cb_no, cb->crossbar_base + cb->register_offsets[irq_no]);
  52 }
  53
  54 static void crossbar_writew(int irq_no, int cb_no)
  55 {
  56         writew(cb_no, cb->crossbar_base + cb->register_offsets[irq_no]);
  57 }
  58
  59 static void crossbar_writeb(int irq_no, int cb_no)
  60 {
  61         writeb(cb_no, cb->crossbar_base + cb->register_offsets[irq_no]);
  62 }
  63
  64 static struct irq_chip crossbar_chip = {
  65         .name                   = "CBAR",
  66         .irq_eoi                = irq_chip_eoi_parent,
  67         .irq_mask               = irq_chip_mask_parent,
  68         .irq_unmask             = irq_chip_unmask_parent,
  69         .irq_retrigger          = irq_chip_retrigger_hierarchy,
  70         .irq_set_type           = irq_chip_set_type_parent,
  71         .flags                  = IRQCHIP_MASK_ON_SUSPEND |
  72                                   IRQCHIP_SKIP_SET_WAKE,
  73 #ifdef CONFIG_SMP
  74         .irq_set_affinity       = irq_chip_set_affinity_parent,
  75 #endif
  76 };
  77
  78 static int allocate_gic_irq(struct irq_domain *domain, unsigned virq,
  79                             irq_hw_number_t hwirq)
  80 {
  81         struct irq_fwspec fwspec;
  82         int i;
  83         int err;
  84
  85         if (!irq_domain_get_of_node(domain->parent))
  86                 return -EINVAL;
  87
  88         raw_spin_lock(&cb->lock);
  89         for (i = cb->int_max - 1; i >= 0; i--) {
  90                 if (cb->irq_map[i] == IRQ_FREE) {
  91                         cb->irq_map[i] = hwirq;
  92                         break;
  93                 }
  94         }
  95         raw_spin_unlock(&cb->lock);
  96
  97         if (i < 0)
  98                 return -ENODEV;
  99
 100         fwspec.fwnode = domain->parent->fwnode;
 101         fwspec.param_count = 3;
 102         fwspec.param[0] = 0;    /* SPI */
 103         fwspec.param[1] = i;
 104         fwspec.param[2] = IRQ_TYPE_LEVEL_HIGH;
 105
 106         err = irq_domain_alloc_irqs_parent(domain, virq, 1, &fwspec);
 107         if (err)
 108                 cb->irq_map[i] = IRQ_FREE;
 109         else
 110                 cb->write(i, hwirq);
 111
 112         return err;
 113 }
 114
 115 static int crossbar_domain_alloc(struct irq_domain *d, unsigned int virq,
 116                                  unsigned int nr_irqs, void *data)
 117 {
 118         struct irq_fwspec *fwspec = data;
 119         irq_hw_number_t hwirq;
 120         int i;
 121
 122         if (fwspec->param_count != 3)
 123                 return -EINVAL; /* Not GIC compliant */
 124         if (fwspec->param[0] != 0)
 125                 return -EINVAL; /* No PPI should point to this domain */
 126
 127         hwirq = fwspec->param[1];
 128         if ((hwirq + nr_irqs) > cb->max_crossbar_sources)
 129                 return -EINVAL; /* Can't deal with this */
 130
 131         for (i = 0; i < nr_irqs; i++) {
 132                 int err = allocate_gic_irq(d, virq + i, hwirq + i);
 133
 134                 if (err)
 135                         return err;
 136
 137                 irq_domain_set_hwirq_and_chip(d, virq + i, hwirq + i,
 138                                               &crossbar_chip, NULL);
 139         }
 140
 141         return 0;
 142 }
 143
 144 /**
 145  * crossbar_domain_free - unmap/free a crossbar<->irq connection
 146  * @domain: domain of irq to unmap
 147  * @virq: virq number
 148  * @nr_irqs: number of irqs to free
 149  *
 150  * We do not maintain a use count of total number of map/unmap
 151  * calls for a particular irq to find out if a irq can be really
 152  * unmapped. This is because unmap is called during irq_dispose_mapping(irq),
 153  * after which irq is anyways unusable. So an explicit map has to be called
 154  * after that.
 155  */
 156 static void crossbar_domain_free(struct irq_domain *domain, unsigned int virq,
 157                                  unsigned int nr_irqs)
 158 {
 159         int i;
 160
 161         raw_spin_lock(&cb->lock);
 162         for (i = 0; i < nr_irqs; i++) {
 163                 struct irq_data *d = irq_domain_get_irq_data(domain, virq + i);
 164
 165                 irq_domain_reset_irq_data(d);
 166                 cb->irq_map[d->hwirq] = IRQ_FREE;
 167                 cb->write(d->hwirq, cb->safe_map);
 168         }
 169         raw_spin_unlock(&cb->lock);
 170 }
 171
 172 static int crossbar_domain_translate(struct irq_domain *d,
 173                                      struct irq_fwspec *fwspec,
 174                                      unsigned long *hwirq,
 175                                      unsigned int *type)
 176 {
 177         if (is_of_node(fwspec->fwnode)) {
 178                 if (fwspec->param_count != 3)
 179                         return -EINVAL;
 180
 181                 /* No PPI should point to this domain */
 182                 if (fwspec->param[0] != 0)
 183                         return -EINVAL;
 184
 185                 *hwirq = fwspec->param[1];
 186                 *type = fwspec->param[2];
 187                 return 0;
 188         }
 189
 190         return -EINVAL;
 191 }
 192
 193 static const struct irq_domain_ops crossbar_domain_ops = {
 194         .alloc          = crossbar_domain_alloc,
 195         .free           = crossbar_domain_free,
 196         .translate      = crossbar_domain_translate,
 197 };
 198
 199 static int __init crossbar_of_init(struct device_node *node)
 200 {
 201         int i, size, reserved = 0;
 202         u32 max = 0, entry, reg_size;
 203         const __be32 *irqsr;
 204         int ret = -ENOMEM;
 205
 206         cb = kzalloc(sizeof(*cb), GFP_KERNEL);
 207
 208         if (!cb)
 209                 return ret;
 210
 211         cb->crossbar_base = of_iomap(node, 0);
 212         if (!cb->crossbar_base)
 213                 goto err_cb;
 214
 215         of_property_read_u32(node, "ti,max-crossbar-sources",
 216                              &cb->max_crossbar_sources);
 217         if (!cb->max_crossbar_sources) {
 218                 pr_err("missing 'ti,max-crossbar-sources' property\n");
 219                 ret = -EINVAL;
 220                 goto err_base;
 221         }
 222
 223         of_property_read_u32(node, "ti,max-irqs", &max);
 224         if (!max) {
 225                 pr_err("missing 'ti,max-irqs' property\n");
 226                 ret = -EINVAL;
 227                 goto err_base;
 228         }
 229         cb->irq_map = kcalloc(max, sizeof(int), GFP_KERNEL);
 230         if (!cb->irq_map)
 231                 goto err_base;
 232
 233         cb->int_max = max;
 234
 235         for (i = 0; i < max; i++)
 236                 cb->irq_map[i] = IRQ_FREE;
 237
 238         /* Get and mark reserved irqs */
 239         irqsr = of_get_property(node, "ti,irqs-reserved", &size);
 240         if (irqsr) {
 241                 size /= sizeof(__be32);
 242
 243                 for (i = 0; i < size; i++) {
 244                         of_property_read_u32_index(node,
 245                                                    "ti,irqs-reserved",
 246                                                    i, &entry);
 247                         if (entry >= max) {
 248                                 pr_err("Invalid reserved entry\n");
 249                                 ret = -EINVAL;
 250                                 goto err_irq_map;
 251                         }
 252                         cb->irq_map[entry] = IRQ_RESERVED;
 253                 }
 254         }
 255
 256         /* Skip irqs hardwired to bypass the crossbar */
 257         irqsr = of_get_property(node, "ti,irqs-skip", &size);
 258         if (irqsr) {
 259                 size /= sizeof(__be32);
 260
 261                 for (i = 0; i < size; i++) {
 262                         of_property_read_u32_index(node,
 263                                                    "ti,irqs-skip",
 264                                                    i, &entry);
 265                         if (entry >= max) {
 266                                 pr_err("Invalid skip entry\n");
 267                                 ret = -EINVAL;
 268                                 goto err_irq_map;
 269                         }
 270                         cb->irq_map[entry] = IRQ_SKIP;
 271                 }
 272         }
 273
 274
 275         cb->register_offsets = kcalloc(max, sizeof(int), GFP_KERNEL);
 276         if (!cb->register_offsets)
 277                 goto err_irq_map;
 278
 279         of_property_read_u32(node, "ti,reg-size", &reg_size);
 280
 281         switch (reg_size) {
 282         case 1:
 283                 cb->write = crossbar_writeb;
 284                 break;
 285         case 2:
 286                 cb->write = crossbar_writew;
 287                 break;
 288         case 4:
 289                 cb->write = crossbar_writel;
 290                 break;
 291         default:
 292                 pr_err("Invalid reg-size property\n");
 293                 ret = -EINVAL;
 294                 goto err_reg_offset;
 295                 break;
 296         }
 297
 298         /*
 299          * Register offsets are not linear because of the
 300          * reserved irqs. so find and store the offsets once.
 301          */
 302         for (i = 0; i < max; i++) {
 303                 if (cb->irq_map[i] == IRQ_RESERVED)
 304                         continue;
 305
 306                 cb->register_offsets[i] = reserved;
 307                 reserved += reg_size;
 308         }
 309
 310         of_property_read_u32(node, "ti,irqs-safe-map", &cb->safe_map);
 311         /* Initialize the crossbar with safe map to start with */
 312         for (i = 0; i < max; i++) {
 313                 if (cb->irq_map[i] == IRQ_RESERVED ||
 314                     cb->irq_map[i] == IRQ_SKIP)
 315                         continue;
 316
 317                 cb->write(i, cb->safe_map);
 318         }
 319
 320         raw_spin_lock_init(&cb->lock);
 321
 322         return 0;
 323
 324 err_reg_offset:
 325         kfree(cb->register_offsets);
 326 err_irq_map:
 327         kfree(cb->irq_map);
 328 err_base:
 329         iounmap(cb->crossbar_base);
 330 err_cb:
 331         kfree(cb);
 332
 333         cb = NULL;
 334         return ret;
 335 }
 336
 337 static int __init irqcrossbar_init(struct device_node *node,
 338                                    struct device_node *parent)
 339 {
 340         struct irq_domain *parent_domain, *domain;
 341         int err;
 342
 343         if (!parent) {
 344                 pr_err("%s: no parent, giving up\n", node->full_name);
 345                 return -ENODEV;
 346         }
 347
 348         parent_domain = irq_find_host(parent);
 349         if (!parent_domain) {
 350                 pr_err("%s: unable to obtain parent domain\n", node->full_name);
 351                 return -ENXIO;
 352         }
 353
 354         err = crossbar_of_init(node);
 355         if (err)
 356                 return err;
 357
 358         domain = irq_domain_add_hierarchy(parent_domain, 0,
 359                                           cb->max_crossbar_sources,
 360                                           node, &crossbar_domain_ops,
 361                                           NULL);
 362         if (!domain) {
 363                 pr_err("%s: failed to allocated domain\n", node->full_name);
 364                 return -ENOMEM;
 365         }
 366
 367         return 0;
 368 }
 369
 370 IRQCHIP_DECLARE(ti_irqcrossbar, "ti,irq-crossbar", irqcrossbar_init);