kernel/irq/ipi.c

   1 /*
   2  * linux/kernel/irq/ipi.c
   3  *
   4  * Copyright (C) 2015 Imagination Technologies Ltd
   5  * Author: Qais Yousef <qais.yousef@imgtec.com>
   6  *
   7  * This file contains driver APIs to the IPI subsystem.
   8  */
   9
  10 #define pr_fmt(fmt) "genirq/ipi: " fmt
  11
  12 #include <linux/irqdomain.h>
  13 #include <linux/irq.h>
  14
  15 /**
  16  * irq_reserve_ipi() - Setup an IPI to destination cpumask
  17  * @domain:     IPI domain
  18  * @dest:       cpumask of cpus which can receive the IPI
  19  *
  20  * Allocate a virq that can be used to send IPI to any CPU in dest mask.
  21  *
  22  * On success it'll return linux irq number and 0 on failure
  23  */
  24 unsigned int irq_reserve_ipi(struct irq_domain *domain,
  25                              const struct cpumask *dest)
  26 {
  27         unsigned int nr_irqs, offset;
  28         struct irq_data *data;
  29         int virq, i;
  30
  31         if (!domain ||!irq_domain_is_ipi(domain)) {
  32                 pr_warn("Reservation on a non IPI domain\n");
  33                 return 0;
  34         }
  35
  36         if (!cpumask_subset(dest, cpu_possible_mask)) {
  37                 pr_warn("Reservation is not in possible_cpu_mask\n");
  38                 return 0;
  39         }
  40
  41         nr_irqs = cpumask_weight(dest);
  42         if (!nr_irqs) {
  43                 pr_warn("Reservation for empty destination mask\n");
  44                 return 0;
  45         }
  46
  47         if (irq_domain_is_ipi_single(domain)) {
  48                 /*
  49                  * If the underlying implementation uses a single HW irq on
  50                  * all cpus then we only need a single Linux irq number for
  51                  * it. We have no restrictions vs. the destination mask. The
  52                  * underlying implementation can deal with holes nicely.
  53                  */
  54                 nr_irqs = 1;
  55                 offset = 0;
  56         } else {
  57                 unsigned int next;
  58
  59                 /*
  60                  * The IPI requires a seperate HW irq on each CPU. We require
  61                  * that the destination mask is consecutive. If an
  62                  * implementation needs to support holes, it can reserve
  63                  * several IPI ranges.
  64                  */
  65                 offset = cpumask_first(dest);
  66                 /*
  67                  * Find a hole and if found look for another set bit after the
  68                  * hole. For now we don't support this scenario.
  69                  */
  70                 next = cpumask_next_zero(offset, dest);
  71                 if (next < nr_cpu_ids)
  72                         next = cpumask_next(next, dest);
  73                 if (next < nr_cpu_ids) {
  74                         pr_warn("Destination mask has holes\n");
  75                         return 0;
  76                 }
  77         }
  78
  79         virq = irq_domain_alloc_descs(-1, nr_irqs, 0, NUMA_NO_NODE);
  80         if (virq <= 0) {
  81                 pr_warn("Can't reserve IPI, failed to alloc descs\n");
  82                 return 0;
  83         }
  84
  85         virq = __irq_domain_alloc_irqs(domain, virq, nr_irqs, NUMA_NO_NODE,
  86                                        (void *) dest, true);
  87
  88         if (virq <= 0) {
  89                 pr_warn("Can't reserve IPI, failed to alloc hw irqs\n");
  90                 goto free_descs;
  91         }
  92
  93         for (i = 0; i < nr_irqs; i++) {
  94                 data = irq_get_irq_data(virq + i);
  95                 cpumask_copy(data->common->affinity, dest);
  96                 data->common->ipi_offset = offset;
  97                 irq_set_status_flags(virq + i, IRQ_NO_BALANCING);
  98         }
  99         return virq;
 100
 101 free_descs:
 102         irq_free_descs(virq, nr_irqs);
 103         return 0;
 104 }
 105
 106 /**
 107  * irq_destroy_ipi() - unreserve an IPI that was previously allocated
 108  * @irq:        linux irq number to be destroyed
 109  *
 110  * Return the IPIs allocated with irq_reserve_ipi() to the system destroying
 111  * all virqs associated with them.
 112  */
 113 void irq_destroy_ipi(unsigned int irq)
 114 {
 115         struct irq_data *data = irq_get_irq_data(irq);
 116         struct cpumask *ipimask = data ? irq_data_get_affinity_mask(data) : NULL;
 117         struct irq_domain *domain;
 118         unsigned int nr_irqs;
 119
 120         if (!irq || !data || !ipimask)
 121                 return;
 122
 123         domain = data->domain;
 124         if (WARN_ON(domain == NULL))
 125                 return;
 126
 127         if (!irq_domain_is_ipi(domain)) {
 128                 pr_warn("Trying to destroy a non IPI domain!\n");
 129                 return;
 130         }
 131
 132         if (irq_domain_is_ipi_per_cpu(domain))
 133                 nr_irqs = cpumask_weight(ipimask);
 134         else
 135                 nr_irqs = 1;
 136
 137         irq_domain_free_irqs(irq, nr_irqs);
 138 }
 139
 140 /**
 141  * ipi_get_hwirq - Get the hwirq associated with an IPI to a cpu
 142  * @irq:        linux irq number
 143  * @cpu:        the target cpu
 144  *
 145  * When dealing with coprocessors IPI, we need to inform the coprocessor of
 146  * the hwirq it needs to use to receive and send IPIs.
 147  *
 148  * Returns hwirq value on success and INVALID_HWIRQ on failure.
 149  */
 150 irq_hw_number_t ipi_get_hwirq(unsigned int irq, unsigned int cpu)
 151 {
 152         struct irq_data *data = irq_get_irq_data(irq);
 153         struct cpumask *ipimask = data ? irq_data_get_affinity_mask(data) : NULL;
 154
 155         if (!data || !ipimask || cpu > nr_cpu_ids)
 156                 return INVALID_HWIRQ;
 157
 158         if (!cpumask_test_cpu(cpu, ipimask))
 159                 return INVALID_HWIRQ;
 160
 161         /*
 162          * Get the real hardware irq number if the underlying implementation
 163          * uses a seperate irq per cpu. If the underlying implementation uses
 164          * a single hardware irq for all cpus then the IPI send mechanism
 165          * needs to take care of the cpu destinations.
 166          */
 167         if (irq_domain_is_ipi_per_cpu(data->domain))
 168                 data = irq_get_irq_data(irq + cpu - data->common->ipi_offset);
 169
 170         return data ? irqd_to_hwirq(data) : INVALID_HWIRQ;
 171 }
 172 EXPORT_SYMBOL_GPL(ipi_get_hwirq);
 173
 174 static int ipi_send_verify(struct irq_chip *chip, struct irq_data *data,
 175                            const struct cpumask *dest, unsigned int cpu)
 176 {
 177         struct cpumask *ipimask = irq_data_get_affinity_mask(data);
 178
 179         if (!chip || !ipimask)
 180                 return -EINVAL;
 181
 182         if (!chip->ipi_send_single && !chip->ipi_send_mask)
 183                 return -EINVAL;
 184
 185         if (cpu > nr_cpu_ids)
 186                 return -EINVAL;
 187
 188         if (dest) {
 189                 if (!cpumask_subset(dest, ipimask))
 190                         return -EINVAL;
 191         } else {
 192                 if (!cpumask_test_cpu(cpu, ipimask))
 193                         return -EINVAL;
 194         }
 195         return 0;
 196 }
 197
 198 /**
 199  * __ipi_send_single - send an IPI to a target Linux SMP CPU
 200  * @desc:       pointer to irq_desc of the IRQ
 201  * @cpu:        destination CPU, must in the destination mask passed to
 202  *              irq_reserve_ipi()
 203  *
 204  * This function is for architecture or core code to speed up IPI sending. Not
 205  * usable from driver code.
 206  *
 207  * Returns zero on success and negative error number on failure.
 208  */
 209 int __ipi_send_single(struct irq_desc *desc, unsigned int cpu)
 210 {
 211         struct irq_data *data = irq_desc_get_irq_data(desc);
 212         struct irq_chip *chip = irq_data_get_irq_chip(data);
 213
 214 #ifdef DEBUG
 215         /*
 216          * Minimise the overhead by omitting the checks for Linux SMP IPIs.
 217          * Since the callers should be arch or core code which is generally
 218          * trusted, only check for errors when debugging.
 219          */
 220         if (WARN_ON_ONCE(ipi_send_verify(chip, data, NULL, cpu)))
 221                 return -EINVAL;
 222 #endif
 223         if (!chip->ipi_send_single) {
 224                 chip->ipi_send_mask(data, cpumask_of(cpu));
 225                 return 0;
 226         }
 227
 228         /* FIXME: Store this information in irqdata flags */
 229         if (irq_domain_is_ipi_per_cpu(data->domain) &&
 230             cpu != data->common->ipi_offset) {
 231                 /* use the correct data for that cpu */
 232                 unsigned irq = data->irq + cpu - data->common->ipi_offset;
 233
 234                 data = irq_get_irq_data(irq);
 235         }
 236         chip->ipi_send_single(data, cpu);
 237         return 0;
 238 }
 239
 240 /**
 241  * ipi_send_mask - send an IPI to target Linux SMP CPU(s)
 242  * @desc:       pointer to irq_desc of the IRQ
 243  * @dest:       dest CPU(s), must be a subset of the mask passed to
 244  *              irq_reserve_ipi()
 245  *
 246  * This function is for architecture or core code to speed up IPI sending. Not
 247  * usable from driver code.
 248  *
 249  * Returns zero on success and negative error number on failure.
 250  */
 251 int __ipi_send_mask(struct irq_desc *desc, const struct cpumask *dest)
 252 {
 253         struct irq_data *data = irq_desc_get_irq_data(desc);
 254         struct irq_chip *chip = irq_data_get_irq_chip(data);
 255         unsigned int cpu;
 256
 257 #ifdef DEBUG
 258         /*
 259          * Minimise the overhead by omitting the checks for Linux SMP IPIs.
 260          * Since the callers should be arch or core code which is generally
 261          * trusted, only check for errors when debugging.
 262          */
 263         if (WARN_ON_ONCE(ipi_send_verify(chip, data, dest, 0)))
 264                 return -EINVAL;
 265 #endif
 266         if (chip->ipi_send_mask) {
 267                 chip->ipi_send_mask(data, dest);
 268                 return 0;
 269         }
 270
 271         if (irq_domain_is_ipi_per_cpu(data->domain)) {
 272                 unsigned int base = data->irq;
 273
 274                 for_each_cpu(cpu, dest) {
 275                         unsigned irq = base + cpu - data->common->ipi_offset;
 276
 277                         data = irq_get_irq_data(irq);
 278                         chip->ipi_send_single(data, cpu);
 279                 }
 280         } else {
 281                 for_each_cpu(cpu, dest)
 282                         chip->ipi_send_single(data, cpu);
 283         }
 284         return 0;
 285 }
 286
 287 /**
 288  * ipi_send_single - Send an IPI to a single CPU
 289  * @virq:       linux irq number from irq_reserve_ipi()
 290  * @cpu:        destination CPU, must in the destination mask passed to
 291  *              irq_reserve_ipi()
 292  *
 293  * Returns zero on success and negative error number on failure.
 294  */
 295 int ipi_send_single(unsigned int virq, unsigned int cpu)
 296 {
 297         struct irq_desc *desc = irq_to_desc(virq);
 298         struct irq_data *data = desc ? irq_desc_get_irq_data(desc) : NULL;
 299         struct irq_chip *chip = data ? irq_data_get_irq_chip(data) : NULL;
 300
 301         if (WARN_ON_ONCE(ipi_send_verify(chip, data, NULL, cpu)))
 302                 return -EINVAL;
 303
 304         return __ipi_send_single(desc, cpu);
 305 }
 306 EXPORT_SYMBOL_GPL(ipi_send_single);
 307
 308 /**
 309  * ipi_send_mask - Send an IPI to target CPU(s)
 310  * @virq:       linux irq number from irq_reserve_ipi()
 311  * @dest:       dest CPU(s), must be a subset of the mask passed to
 312  *              irq_reserve_ipi()
 313  *
 314  * Returns zero on success and negative error number on failure.
 315  */
 316 int ipi_send_mask(unsigned int virq, const struct cpumask *dest)
 317 {
 318         struct irq_desc *desc = irq_to_desc(virq);
 319         struct irq_data *data = desc ? irq_desc_get_irq_data(desc) : NULL;
 320         struct irq_chip *chip = data ? irq_data_get_irq_chip(data) : NULL;
 321
 322         if (WARN_ON_ONCE(ipi_send_verify(chip, data, dest, 0)))
 323                 return -EINVAL;
 324
 325         return __ipi_send_mask(desc, dest);
 326 }
 327 EXPORT_SYMBOL_GPL(ipi_send_mask);