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/of_address.h>
  15 #include <linux/of_irq.h>
  16 #include <linux/slab.h>
  17 #include <linux/irqchip/arm-gic.h>
  18 #include <linux/irqchip/irq-crossbar.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  * @int_max: maximum number of supported interrupts
  28  * @safe_map: safe default value to initialize the crossbar
  29  * @max_crossbar_sources: Maximum number of crossbar sources
  30  * @irq_map: array of interrupts to crossbar number mapping
  31  * @crossbar_base: crossbar base address
  32  * @register_offsets: offsets for each irq number
  33  * @write: register write function pointer
  34  */
  35 struct crossbar_device {
  36         uint int_max;
  37         uint safe_map;
  38         uint max_crossbar_sources;
  39         uint *irq_map;
  40         void __iomem *crossbar_base;
  41         int *register_offsets;
  42         void (*write)(int, int);
  43 };
  44
  45 static struct crossbar_device *cb;
  46
  47 static inline void crossbar_writel(int irq_no, int cb_no)
  48 {
  49         writel(cb_no, cb->crossbar_base + cb->register_offsets[irq_no]);
  50 }
  51
  52 static inline void crossbar_writew(int irq_no, int cb_no)
  53 {
  54         writew(cb_no, cb->crossbar_base + cb->register_offsets[irq_no]);
  55 }
  56
  57 static inline void crossbar_writeb(int irq_no, int cb_no)
  58 {
  59         writeb(cb_no, cb->crossbar_base + cb->register_offsets[irq_no]);
  60 }
  61
  62 static inline int get_prev_map_irq(int cb_no)
  63 {
  64         int i;
  65
  66         for (i = cb->int_max - 1; i >= 0; i--)
  67                 if (cb->irq_map[i] == cb_no)
  68                         return i;
  69
  70         return -ENODEV;
  71 }
  72
  73 static inline int allocate_free_irq(int cb_no)
  74 {
  75         int i;
  76
  77         for (i = cb->int_max - 1; i >= 0; i--) {
  78                 if (cb->irq_map[i] == IRQ_FREE) {
  79                         cb->irq_map[i] = cb_no;
  80                         return i;
  81                 }
  82         }
  83
  84         return -ENODEV;
  85 }
  86
  87 static inline bool needs_crossbar_write(irq_hw_number_t hw)
  88 {
  89         int cb_no;
  90
  91         if (hw > GIC_IRQ_START) {
  92                 cb_no = cb->irq_map[hw - GIC_IRQ_START];
  93                 if (cb_no != IRQ_RESERVED && cb_no != IRQ_SKIP)
  94                         return true;
  95         }
  96
  97         return false;
  98 }
  99
 100 static int crossbar_domain_map(struct irq_domain *d, unsigned int irq,
 101                                irq_hw_number_t hw)
 102 {
 103         if (needs_crossbar_write(hw))
 104                 cb->write(hw - GIC_IRQ_START, cb->irq_map[hw - GIC_IRQ_START]);
 105
 106         return 0;
 107 }
 108
 109 /**
 110  * crossbar_domain_unmap - unmap a crossbar<->irq connection
 111  * @d: domain of irq to unmap
 112  * @irq: virq number
 113  *
 114  * We do not maintain a use count of total number of map/unmap
 115  * calls for a particular irq to find out if a irq can be really
 116  * unmapped. This is because unmap is called during irq_dispose_mapping(irq),
 117  * after which irq is anyways unusable. So an explicit map has to be called
 118  * after that.
 119  */
 120 static void crossbar_domain_unmap(struct irq_domain *d, unsigned int irq)
 121 {
 122         irq_hw_number_t hw = irq_get_irq_data(irq)->hwirq;
 123
 124         if (needs_crossbar_write(hw)) {
 125                 cb->irq_map[hw - GIC_IRQ_START] = IRQ_FREE;
 126                 cb->write(hw - GIC_IRQ_START, cb->safe_map);
 127         }
 128 }
 129
 130 static int crossbar_domain_xlate(struct irq_domain *d,
 131                                  struct device_node *controller,
 132                                  const u32 *intspec, unsigned int intsize,
 133                                  unsigned long *out_hwirq,
 134                                  unsigned int *out_type)
 135 {
 136         int ret;
 137         int req_num = intspec[1];
 138         int direct_map_num;
 139
 140         if (req_num >= cb->max_crossbar_sources) {
 141                 direct_map_num = req_num - cb->max_crossbar_sources;
 142                 if (direct_map_num < cb->int_max) {
 143                         ret = cb->irq_map[direct_map_num];
 144                         if (ret == IRQ_RESERVED || ret == IRQ_SKIP) {
 145                                 /* We use the interrupt num as h/w irq num */
 146                                 ret = direct_map_num;
 147                                 goto found;
 148                         }
 149                 }
 150
 151                 pr_err("%s: requested crossbar number %d > max %d\n",
 152                        __func__, req_num, cb->max_crossbar_sources);
 153                 return -EINVAL;
 154         }
 155
 156         ret = get_prev_map_irq(req_num);
 157         if (ret >= 0)
 158                 goto found;
 159
 160         ret = allocate_free_irq(req_num);
 161
 162         if (ret < 0)
 163                 return ret;
 164
 165 found:
 166         *out_hwirq = ret + GIC_IRQ_START;
 167         return 0;
 168 }
 169
 170 static const struct irq_domain_ops routable_irq_domain_ops = {
 171         .map = crossbar_domain_map,
 172         .unmap = crossbar_domain_unmap,
 173         .xlate = crossbar_domain_xlate
 174 };
 175
 176 static int __init crossbar_of_init(struct device_node *node)
 177 {
 178         int i, size, max = 0, reserved = 0, entry;
 179         const __be32 *irqsr;
 180         int ret = -ENOMEM;
 181
 182         cb = kzalloc(sizeof(*cb), GFP_KERNEL);
 183
 184         if (!cb)
 185                 return ret;
 186
 187         cb->crossbar_base = of_iomap(node, 0);
 188         if (!cb->crossbar_base)
 189                 goto err_cb;
 190
 191         of_property_read_u32(node, "ti,max-crossbar-sources",
 192                              &cb->max_crossbar_sources);
 193         if (!cb->max_crossbar_sources) {
 194                 pr_err("missing 'ti,max-crossbar-sources' property\n");
 195                 ret = -EINVAL;
 196                 goto err_base;
 197         }
 198
 199         of_property_read_u32(node, "ti,max-irqs", &max);
 200         if (!max) {
 201                 pr_err("missing 'ti,max-irqs' property\n");
 202                 ret = -EINVAL;
 203                 goto err_base;
 204         }
 205         cb->irq_map = kcalloc(max, sizeof(int), GFP_KERNEL);
 206         if (!cb->irq_map)
 207                 goto err_base;
 208
 209         cb->int_max = max;
 210
 211         for (i = 0; i < max; i++)
 212                 cb->irq_map[i] = IRQ_FREE;
 213
 214         /* Get and mark reserved irqs */
 215         irqsr = of_get_property(node, "ti,irqs-reserved", &size);
 216         if (irqsr) {
 217                 size /= sizeof(__be32);
 218
 219                 for (i = 0; i < size; i++) {
 220                         of_property_read_u32_index(node,
 221                                                    "ti,irqs-reserved",
 222                                                    i, &entry);
 223                         if (entry >= max) {
 224                                 pr_err("Invalid reserved entry\n");
 225                                 ret = -EINVAL;
 226                                 goto err_irq_map;
 227                         }
 228                         cb->irq_map[entry] = IRQ_RESERVED;
 229                 }
 230         }
 231
 232         /* Skip irqs hardwired to bypass the crossbar */
 233         irqsr = of_get_property(node, "ti,irqs-skip", &size);
 234         if (irqsr) {
 235                 size /= sizeof(__be32);
 236
 237                 for (i = 0; i < size; i++) {
 238                         of_property_read_u32_index(node,
 239                                                    "ti,irqs-skip",
 240                                                    i, &entry);
 241                         if (entry >= max) {
 242                                 pr_err("Invalid skip entry\n");
 243                                 ret = -EINVAL;
 244                                 goto err_irq_map;
 245                         }
 246                         cb->irq_map[entry] = IRQ_SKIP;
 247                 }
 248         }
 249
 250
 251         cb->register_offsets = kcalloc(max, sizeof(int), GFP_KERNEL);
 252         if (!cb->register_offsets)
 253                 goto err_irq_map;
 254
 255         of_property_read_u32(node, "ti,reg-size", &size);
 256
 257         switch (size) {
 258         case 1:
 259                 cb->write = crossbar_writeb;
 260                 break;
 261         case 2:
 262                 cb->write = crossbar_writew;
 263                 break;
 264         case 4:
 265                 cb->write = crossbar_writel;
 266                 break;
 267         default:
 268                 pr_err("Invalid reg-size property\n");
 269                 ret = -EINVAL;
 270                 goto err_reg_offset;
 271                 break;
 272         }
 273
 274         /*
 275          * Register offsets are not linear because of the
 276          * reserved irqs. so find and store the offsets once.
 277          */
 278         for (i = 0; i < max; i++) {
 279                 if (cb->irq_map[i] == IRQ_RESERVED)
 280                         continue;
 281
 282                 cb->register_offsets[i] = reserved;
 283                 reserved += size;
 284         }
 285
 286         of_property_read_u32(node, "ti,irqs-safe-map", &cb->safe_map);
 287         /* Initialize the crossbar with safe map to start with */
 288         for (i = 0; i < max; i++) {
 289                 if (cb->irq_map[i] == IRQ_RESERVED ||
 290                     cb->irq_map[i] == IRQ_SKIP)
 291                         continue;
 292
 293                 cb->write(i, cb->safe_map);
 294         }
 295
 296         register_routable_domain_ops(&routable_irq_domain_ops);
 297         return 0;
 298
 299 err_reg_offset:
 300         kfree(cb->register_offsets);
 301 err_irq_map:
 302         kfree(cb->irq_map);
 303 err_base:
 304         iounmap(cb->crossbar_base);
 305 err_cb:
 306         kfree(cb);
 307
 308         cb = NULL;
 309         return ret;
 310 }
 311
 312 static const struct of_device_id crossbar_match[] __initconst = {
 313         { .compatible = "ti,irq-crossbar" },
 314         {}
 315 };
 316
 317 int __init irqcrossbar_init(void)
 318 {
 319         struct device_node *np;
 320         np = of_find_matching_node(NULL, crossbar_match);
 321         if (!np)
 322                 return -ENODEV;
 323
 324         crossbar_of_init(np);
 325         return 0;
 326 }