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  * @irq_map: array of interrupts to crossbar number mapping
  30  * @crossbar_base: crossbar base address
  31  * @register_offsets: offsets for each irq number
  32  * @write: register write function pointer
  33  */
  34 struct crossbar_device {
  35         uint int_max;
  36         uint safe_map;
  37         uint *irq_map;
  38         void __iomem *crossbar_base;
  39         int *register_offsets;
  40         void (*write)(int, int);
  41 };
  42
  43 static struct crossbar_device *cb;
  44
  45 static inline void crossbar_writel(int irq_no, int cb_no)
  46 {
  47         writel(cb_no, cb->crossbar_base + cb->register_offsets[irq_no]);
  48 }
  49
  50 static inline void crossbar_writew(int irq_no, int cb_no)
  51 {
  52         writew(cb_no, cb->crossbar_base + cb->register_offsets[irq_no]);
  53 }
  54
  55 static inline void crossbar_writeb(int irq_no, int cb_no)
  56 {
  57         writeb(cb_no, cb->crossbar_base + cb->register_offsets[irq_no]);
  58 }
  59
  60 static inline int get_prev_map_irq(int cb_no)
  61 {
  62         int i;
  63
  64         for (i = cb->int_max - 1; i >= 0; i--)
  65                 if (cb->irq_map[i] == cb_no)
  66                         return i;
  67
  68         return -ENODEV;
  69 }
  70
  71 static inline int allocate_free_irq(int cb_no)
  72 {
  73         int i;
  74
  75         for (i = cb->int_max - 1; i >= 0; i--) {
  76                 if (cb->irq_map[i] == IRQ_FREE) {
  77                         cb->irq_map[i] = cb_no;
  78                         return i;
  79                 }
  80         }
  81
  82         return -ENODEV;
  83 }
  84
  85 static int crossbar_domain_map(struct irq_domain *d, unsigned int irq,
  86                                irq_hw_number_t hw)
  87 {
  88         cb->write(hw - GIC_IRQ_START, cb->irq_map[hw - GIC_IRQ_START]);
  89         return 0;
  90 }
  91
  92 static void crossbar_domain_unmap(struct irq_domain *d, unsigned int irq)
  93 {
  94         irq_hw_number_t hw = irq_get_irq_data(irq)->hwirq;
  95
  96         if (hw > GIC_IRQ_START) {
  97                 cb->irq_map[hw - GIC_IRQ_START] = IRQ_FREE;
  98                 cb->write(hw - GIC_IRQ_START, cb->safe_map);
  99         }
 100 }
 101
 102 static int crossbar_domain_xlate(struct irq_domain *d,
 103                                  struct device_node *controller,
 104                                  const u32 *intspec, unsigned int intsize,
 105                                  unsigned long *out_hwirq,
 106                                  unsigned int *out_type)
 107 {
 108         int ret;
 109
 110         ret = get_prev_map_irq(intspec[1]);
 111         if (ret >= 0)
 112                 goto found;
 113
 114         ret = allocate_free_irq(intspec[1]);
 115
 116         if (ret < 0)
 117                 return ret;
 118
 119 found:
 120         *out_hwirq = ret + GIC_IRQ_START;
 121         return 0;
 122 }
 123
 124 static const struct irq_domain_ops routable_irq_domain_ops = {
 125         .map = crossbar_domain_map,
 126         .unmap = crossbar_domain_unmap,
 127         .xlate = crossbar_domain_xlate
 128 };
 129
 130 static int __init crossbar_of_init(struct device_node *node)
 131 {
 132         int i, size, max, reserved = 0, entry;
 133         const __be32 *irqsr;
 134
 135         cb = kzalloc(sizeof(*cb), GFP_KERNEL);
 136
 137         if (!cb)
 138                 return -ENOMEM;
 139
 140         cb->crossbar_base = of_iomap(node, 0);
 141         if (!cb->crossbar_base)
 142                 goto err1;
 143
 144         of_property_read_u32(node, "ti,max-irqs", &max);
 145         cb->irq_map = kcalloc(max, sizeof(int), GFP_KERNEL);
 146         if (!cb->irq_map)
 147                 goto err2;
 148
 149         cb->int_max = max;
 150
 151         for (i = 0; i < max; i++)
 152                 cb->irq_map[i] = IRQ_FREE;
 153
 154         /* Get and mark reserved irqs */
 155         irqsr = of_get_property(node, "ti,irqs-reserved", &size);
 156         if (irqsr) {
 157                 size /= sizeof(__be32);
 158
 159                 for (i = 0; i < size; i++) {
 160                         of_property_read_u32_index(node,
 161                                                    "ti,irqs-reserved",
 162                                                    i, &entry);
 163                         if (entry > max) {
 164                                 pr_err("Invalid reserved entry\n");
 165                                 goto err3;
 166                         }
 167                         cb->irq_map[entry] = IRQ_RESERVED;
 168                 }
 169         }
 170
 171         /* Skip irqs hardwired to bypass the crossbar */
 172         irqsr = of_get_property(node, "ti,irqs-skip", &size);
 173         if (irqsr) {
 174                 size /= sizeof(__be32);
 175
 176                 for (i = 0; i < size; i++) {
 177                         of_property_read_u32_index(node,
 178                                                    "ti,irqs-skip",
 179                                                    i, &entry);
 180                         if (entry > max) {
 181                                 pr_err("Invalid skip entry\n");
 182                                 ret = -EINVAL;
 183                                 goto err3;
 184                         }
 185                         cb->irq_map[entry] = IRQ_SKIP;
 186                 }
 187         }
 188
 189
 190         cb->register_offsets = kcalloc(max, sizeof(int), GFP_KERNEL);
 191         if (!cb->register_offsets)
 192                 goto err3;
 193
 194         of_property_read_u32(node, "ti,reg-size", &size);
 195
 196         switch (size) {
 197         case 1:
 198                 cb->write = crossbar_writeb;
 199                 break;
 200         case 2:
 201                 cb->write = crossbar_writew;
 202                 break;
 203         case 4:
 204                 cb->write = crossbar_writel;
 205                 break;
 206         default:
 207                 pr_err("Invalid reg-size property\n");
 208                 goto err4;
 209                 break;
 210         }
 211
 212         /*
 213          * Register offsets are not linear because of the
 214          * reserved irqs. so find and store the offsets once.
 215          */
 216         for (i = 0; i < max; i++) {
 217                 if (cb->irq_map[i] == IRQ_RESERVED)
 218                         continue;
 219
 220                 cb->register_offsets[i] = reserved;
 221                 reserved += size;
 222         }
 223
 224         of_property_read_u32(node, "ti,irqs-safe-map", &cb->safe_map);
 225
 226         /* Initialize the crossbar with safe map to start with */
 227         for (i = 0; i < max; i++) {
 228                 if (cb->irq_map[i] == IRQ_RESERVED ||
 229                     cb->irq_map[i] == IRQ_SKIP)
 230                         continue;
 231
 232                 cb->write(i, cb->safe_map);
 233         }
 234
 235         register_routable_domain_ops(&routable_irq_domain_ops);
 236         return 0;
 237
 238 err4:
 239         kfree(cb->register_offsets);
 240 err3:
 241         kfree(cb->irq_map);
 242 err2:
 243         iounmap(cb->crossbar_base);
 244 err1:
 245         kfree(cb);
 246         return -ENOMEM;
 247 }
 248
 249 static const struct of_device_id crossbar_match[] __initconst = {
 250         { .compatible = "ti,irq-crossbar" },
 251         {}
 252 };
 253
 254 int __init irqcrossbar_init(void)
 255 {
 256         struct device_node *np;
 257         np = of_find_matching_node(NULL, crossbar_match);
 258         if (!np)
 259                 return -ENODEV;
 260
 261         crossbar_of_init(np);
 262         return 0;
 263 }