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 = 0, reserved = 0, entry;
 133         const __be32 *irqsr;
 134         int ret = -ENOMEM;
 135
 136         cb = kzalloc(sizeof(*cb), GFP_KERNEL);
 137
 138         if (!cb)
 139                 return ret;
 140
 141         cb->crossbar_base = of_iomap(node, 0);
 142         if (!cb->crossbar_base)
 143                 goto err1;
 144
 145         of_property_read_u32(node, "ti,max-irqs", &max);
 146         if (!max) {
 147                 pr_err("missing 'ti,max-irqs' property\n");
 148                 ret = -EINVAL;
 149                 goto err2;
 150         }
 151         cb->irq_map = kcalloc(max, sizeof(int), GFP_KERNEL);
 152         if (!cb->irq_map)
 153                 goto err2;
 154
 155         cb->int_max = max;
 156
 157         for (i = 0; i < max; i++)
 158                 cb->irq_map[i] = IRQ_FREE;
 159
 160         /* Get and mark reserved irqs */
 161         irqsr = of_get_property(node, "ti,irqs-reserved", &size);
 162         if (irqsr) {
 163                 size /= sizeof(__be32);
 164
 165                 for (i = 0; i < size; i++) {
 166                         of_property_read_u32_index(node,
 167                                                    "ti,irqs-reserved",
 168                                                    i, &entry);
 169                         if (entry > max) {
 170                                 pr_err("Invalid reserved entry\n");
 171                                 ret = -EINVAL;
 172                                 goto err3;
 173                         }
 174                         cb->irq_map[entry] = IRQ_RESERVED;
 175                 }
 176         }
 177
 178         /* Skip irqs hardwired to bypass the crossbar */
 179         irqsr = of_get_property(node, "ti,irqs-skip", &size);
 180         if (irqsr) {
 181                 size /= sizeof(__be32);
 182
 183                 for (i = 0; i < size; i++) {
 184                         of_property_read_u32_index(node,
 185                                                    "ti,irqs-skip",
 186                                                    i, &entry);
 187                         if (entry > max) {
 188                                 pr_err("Invalid skip entry\n");
 189                                 ret = -EINVAL;
 190                                 goto err3;
 191                         }
 192                         cb->irq_map[entry] = IRQ_SKIP;
 193                 }
 194         }
 195
 196
 197         cb->register_offsets = kcalloc(max, sizeof(int), GFP_KERNEL);
 198         if (!cb->register_offsets)
 199                 goto err3;
 200
 201         of_property_read_u32(node, "ti,reg-size", &size);
 202
 203         switch (size) {
 204         case 1:
 205                 cb->write = crossbar_writeb;
 206                 break;
 207         case 2:
 208                 cb->write = crossbar_writew;
 209                 break;
 210         case 4:
 211                 cb->write = crossbar_writel;
 212                 break;
 213         default:
 214                 pr_err("Invalid reg-size property\n");
 215                 ret = -EINVAL;
 216                 goto err4;
 217                 break;
 218         }
 219
 220         /*
 221          * Register offsets are not linear because of the
 222          * reserved irqs. so find and store the offsets once.
 223          */
 224         for (i = 0; i < max; i++) {
 225                 if (cb->irq_map[i] == IRQ_RESERVED)
 226                         continue;
 227
 228                 cb->register_offsets[i] = reserved;
 229                 reserved += size;
 230         }
 231
 232         of_property_read_u32(node, "ti,irqs-safe-map", &cb->safe_map);
 233
 234         /* Initialize the crossbar with safe map to start with */
 235         for (i = 0; i < max; i++) {
 236                 if (cb->irq_map[i] == IRQ_RESERVED ||
 237                     cb->irq_map[i] == IRQ_SKIP)
 238                         continue;
 239
 240                 cb->write(i, cb->safe_map);
 241         }
 242
 243         register_routable_domain_ops(&routable_irq_domain_ops);
 244         return 0;
 245
 246 err4:
 247         kfree(cb->register_offsets);
 248 err3:
 249         kfree(cb->irq_map);
 250 err2:
 251         iounmap(cb->crossbar_base);
 252 err1:
 253         kfree(cb);
 254         return ret;
 255 }
 256
 257 static const struct of_device_id crossbar_match[] __initconst = {
 258         { .compatible = "ti,irq-crossbar" },
 259         {}
 260 };
 261
 262 int __init irqcrossbar_init(void)
 263 {
 264         struct device_node *np;
 265         np = of_find_matching_node(NULL, crossbar_match);
 266         if (!np)
 267                 return -ENODEV;
 268
 269         crossbar_of_init(np);
 270         return 0;
 271 }