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         }
  98         return virq;
  99
 100 free_descs:
 101         irq_free_descs(virq, nr_irqs);
 102         return 0;
 103 }
 104
 105 /**
 106  * irq_destroy_ipi() - unreserve an IPI that was previously allocated
 107  * @irq:        linux irq number to be destroyed
 108  *
 109  * Return the IPIs allocated with irq_reserve_ipi() to the system destroying
 110  * all virqs associated with them.
 111  */
 112 void irq_destroy_ipi(unsigned int irq)
 113 {
 114         struct irq_data *data = irq_get_irq_data(irq);
 115         struct cpumask *ipimask = data ? irq_data_get_affinity_mask(data) : NULL;
 116         struct irq_domain *domain;
 117         unsigned int nr_irqs;
 118
 119         if (!irq || !data || !ipimask)
 120                 return;
 121
 122         domain = data->domain;
 123         if (WARN_ON(domain == NULL))
 124                 return;
 125
 126         if (!irq_domain_is_ipi(domain)) {
 127                 pr_warn("Trying to destroy a non IPI domain!\n");
 128                 return;
 129         }
 130
 131         if (irq_domain_is_ipi_per_cpu(domain))
 132                 nr_irqs = cpumask_weight(ipimask);
 133         else
 134                 nr_irqs = 1;
 135
 136         irq_domain_free_irqs(irq, nr_irqs);
 137 }
 138
 139 /**
 140  * ipi_get_hwirq - Get the hwirq associated with an IPI to a cpu
 141  * @irq:        linux irq number
 142  * @cpu:        the target cpu
 143  *
 144  * When dealing with coprocessors IPI, we need to inform the coprocessor of
 145  * the hwirq it needs to use to receive and send IPIs.
 146  *
 147  * Returns hwirq value on success and INVALID_HWIRQ on failure.
 148  */
 149 irq_hw_number_t ipi_get_hwirq(unsigned int irq, unsigned int cpu)
 150 {
 151         struct irq_data *data = irq_get_irq_data(irq);
 152         struct cpumask *ipimask = data ? irq_data_get_affinity_mask(data) : NULL;
 153
 154         if (!data || !ipimask || cpu > nr_cpu_ids)
 155                 return INVALID_HWIRQ;
 156
 157         if (!cpumask_test_cpu(cpu, ipimask))
 158                 return INVALID_HWIRQ;
 159
 160         /*
 161          * Get the real hardware irq number if the underlying implementation
 162          * uses a seperate irq per cpu. If the underlying implementation uses
 163          * a single hardware irq for all cpus then the IPI send mechanism
 164          * needs to take care of the cpu destinations.
 165          */
 166         if (irq_domain_is_ipi_per_cpu(data->domain))
 167                 data = irq_get_irq_data(irq + cpu - data->common->ipi_offset);
 168
 169         return data ? irqd_to_hwirq(data) : INVALID_HWIRQ;
 170 }
 171 EXPORT_SYMBOL_GPL(ipi_get_hwirq);
 172
 173 static int ipi_send_verify(struct irq_chip *chip, struct irq_data *data,
 174                            const struct cpumask *dest, unsigned int cpu)
 175 {
 176         struct cpumask *ipimask = irq_data_get_affinity_mask(data);
 177
 178         if (!chip || !ipimask)
 179                 return -EINVAL;
 180
 181         if (!chip->ipi_send_single && !chip->ipi_send_mask)
 182                 return -EINVAL;
 183
 184         if (cpu > nr_cpu_ids)
 185                 return -EINVAL;
 186
 187         if (dest) {
 188                 if (!cpumask_subset(dest, ipimask))
 189                         return -EINVAL;
 190         } else {
 191                 if (!cpumask_test_cpu(cpu, ipimask))
 192                         return -EINVAL;
 193         }
 194         return 0;
 195 }
 196
 197 /**
 198  * __ipi_send_single - send an IPI to a target Linux SMP CPU
 199  * @desc:       pointer to irq_desc of the IRQ
 200  * @cpu:        destination CPU, must in the destination mask passed to
 201  *              irq_reserve_ipi()
 202  *
 203  * This function is for architecture or core code to speed up IPI sending. Not
 204  * usable from driver code.
 205  *
 206  * Returns zero on success and negative error number on failure.
 207  */
 208 int __ipi_send_single(struct irq_desc *desc, unsigned int cpu)
 209 {
 210         struct irq_data *data = irq_desc_get_irq_data(desc);
 211         struct irq_chip *chip = irq_data_get_irq_chip(data);
 212
 213 #ifdef DEBUG
 214         /*
 215          * Minimise the overhead by omitting the checks for Linux SMP IPIs.
 216          * Since the callers should be arch or core code which is generally
 217          * trusted, only check for errors when debugging.
 218          */
 219         if (WARN_ON_ONCE(ipi_send_verify(chip, data, NULL, cpu)))
 220                 return -EINVAL;
 221 #endif
 222         if (!chip->ipi_send_single) {
 223                 chip->ipi_send_mask(data, cpumask_of(cpu));
 224                 return 0;
 225         }
 226
 227         /* FIXME: Store this information in irqdata flags */
 228         if (irq_domain_is_ipi_per_cpu(data->domain) &&
 229             cpu != data->common->ipi_offset) {
 230                 /* use the correct data for that cpu */
 231                 unsigned irq = data->irq + cpu - data->common->ipi_offset;
 232
 233                 data = irq_get_irq_data(irq);
 234         }
 235         chip->ipi_send_single(data, cpu);
 236         return 0;
 237 }
 238
 239 /**
 240  * ipi_send_mask - send an IPI to target Linux SMP CPU(s)
 241  * @desc:       pointer to irq_desc of the IRQ
 242  * @dest:       dest CPU(s), must be a subset of the mask passed to
 243  *              irq_reserve_ipi()
 244  *
 245  * This function is for architecture or core code to speed up IPI sending. Not
 246  * usable from driver code.
 247  *
 248  * Returns zero on success and negative error number on failure.
 249  */
 250 int __ipi_send_mask(struct irq_desc *desc, const struct cpumask *dest)
 251 {
 252         struct irq_data *data = irq_desc_get_irq_data(desc);
 253         struct irq_chip *chip = irq_data_get_irq_chip(data);
 254         unsigned int cpu;
 255
 256 #ifdef DEBUG
 257         /*
 258          * Minimise the overhead by omitting the checks for Linux SMP IPIs.
 259          * Since the callers should be arch or core code which is generally
 260          * trusted, only check for errors when debugging.
 261          */
 262         if (WARN_ON_ONCE(ipi_send_verify(chip, data, dest, 0)))
 263                 return -EINVAL;
 264 #endif
 265         if (chip->ipi_send_mask) {
 266                 chip->ipi_send_mask(data, dest);
 267                 return 0;
 268         }
 269
 270         if (irq_domain_is_ipi_per_cpu(data->domain)) {
 271                 unsigned int base = data->irq;
 272
 273                 for_each_cpu(cpu, dest) {
 274                         unsigned irq = base + cpu - data->common->ipi_offset;
 275
 276                         data = irq_get_irq_data(irq);
 277                         chip->ipi_send_single(data, cpu);
 278                 }
 279         } else {
 280                 for_each_cpu(cpu, dest)
 281                         chip->ipi_send_single(data, cpu);
 282         }
 283         return 0;
 284 }
 285
 286 /**
 287  * ipi_send_single - Send an IPI to a single CPU
 288  * @virq:       linux irq number from irq_reserve_ipi()
 289  * @cpu:        destination CPU, must in the destination mask passed to
 290  *              irq_reserve_ipi()
 291  *
 292  * Returns zero on success and negative error number on failure.
 293  */
 294 int ipi_send_single(unsigned int virq, unsigned int cpu)
 295 {
 296         struct irq_desc *desc = irq_to_desc(virq);
 297         struct irq_data *data = desc ? irq_desc_get_irq_data(desc) : NULL;
 298         struct irq_chip *chip = data ? irq_data_get_irq_chip(data) : NULL;
 299
 300         if (WARN_ON_ONCE(ipi_send_verify(chip, data, NULL, cpu)))
 301                 return -EINVAL;
 302
 303         return __ipi_send_single(desc, cpu);
 304 }
 305 EXPORT_SYMBOL_GPL(ipi_send_single);
 306
 307 /**
 308  * ipi_send_mask - Send an IPI to target CPU(s)
 309  * @virq:       linux irq number from irq_reserve_ipi()
 310  * @dest:       dest CPU(s), must be a subset of the mask passed to
 311  *              irq_reserve_ipi()
 312  *
 313  * Returns zero on success and negative error number on failure.
 314  */
 315 int ipi_send_mask(unsigned int virq, const struct cpumask *dest)
 316 {
 317         struct irq_desc *desc = irq_to_desc(virq);
 318         struct irq_data *data = desc ? irq_desc_get_irq_data(desc) : NULL;
 319         struct irq_chip *chip = data ? irq_data_get_irq_chip(data) : NULL;
 320
 321         if (WARN_ON_ONCE(ipi_send_verify(chip, data, dest, 0)))
 322                 return -EINVAL;
 323
 324         return __ipi_send_mask(desc, dest);
 325 }
 326 EXPORT_SYMBOL_GPL(ipi_send_mask);