sound/firewire/cmp.c

   1 /*
   2  * Connection Management Procedures (IEC 61883-1) helper functions
   3  *
   4  * Copyright (c) Clemens Ladisch <clemens@ladisch.de>
   5  * Licensed under the terms of the GNU General Public License, version 2.
   6  */
   7
   8 #include <linux/device.h>
   9 #include <linux/firewire.h>
  10 #include <linux/firewire-constants.h>
  11 #include <linux/module.h>
  12 #include <linux/sched.h>
  13 #include "lib.h"
  14 #include "iso-resources.h"
  15 #include "cmp.h"
  16
  17 #define IMPR_SPEED_MASK         0xc0000000
  18 #define IMPR_SPEED_SHIFT        30
  19 #define IMPR_XSPEED_MASK        0x00000060
  20 #define IMPR_XSPEED_SHIFT       5
  21 #define IMPR_PLUGS_MASK         0x0000001f
  22
  23 #define IPCR_ONLINE             0x80000000
  24 #define IPCR_BCAST_CONN         0x40000000
  25 #define IPCR_P2P_CONN_MASK      0x3f000000
  26 #define IPCR_P2P_CONN_SHIFT     24
  27 #define IPCR_CHANNEL_MASK       0x003f0000
  28 #define IPCR_CHANNEL_SHIFT      16
  29
  30 enum bus_reset_handling {
  31         ABORT_ON_BUS_RESET,
  32         SUCCEED_ON_BUS_RESET,
  33 };
  34
  35 static __printf(2, 3)
  36 void cmp_error(struct cmp_connection *c, const char *fmt, ...)
  37 {
  38         va_list va;
  39
  40         va_start(va, fmt);
  41         dev_err(&c->resources.unit->device, "%cPCR%u: %pV",
  42                 'i', c->pcr_index, &(struct va_format){ fmt, &va });
  43         va_end(va);
  44 }
  45
  46 static int pcr_modify(struct cmp_connection *c,
  47                       __be32 (*modify)(struct cmp_connection *c, __be32 old),
  48                       int (*check)(struct cmp_connection *c, __be32 pcr),
  49                       enum bus_reset_handling bus_reset_handling)
  50 {
  51         struct fw_device *device = fw_parent_device(c->resources.unit);
  52         int generation = c->resources.generation;
  53         int rcode, errors = 0;
  54         __be32 old_arg, buffer[2];
  55         int err;
  56
  57         buffer[0] = c->last_pcr_value;
  58         for (;;) {
  59                 old_arg = buffer[0];
  60                 buffer[1] = modify(c, buffer[0]);
  61
  62                 rcode = fw_run_transaction(
  63                                 device->card, TCODE_LOCK_COMPARE_SWAP,
  64                                 device->node_id, generation, device->max_speed,
  65                                 CSR_REGISTER_BASE + CSR_IPCR(c->pcr_index),
  66                                 buffer, 8);
  67
  68                 if (rcode == RCODE_COMPLETE) {
  69                         if (buffer[0] == old_arg) /* success? */
  70                                 break;
  71
  72                         if (check) {
  73                                 err = check(c, buffer[0]);
  74                                 if (err < 0)
  75                                         return err;
  76                         }
  77                 } else if (rcode == RCODE_GENERATION)
  78                         goto bus_reset;
  79                 else if (rcode_is_permanent_error(rcode) || ++errors >= 3)
  80                         goto io_error;
  81         }
  82         c->last_pcr_value = buffer[1];
  83
  84         return 0;
  85
  86 io_error:
  87         cmp_error(c, "transaction failed: %s\n", fw_rcode_string(rcode));
  88         return -EIO;
  89
  90 bus_reset:
  91         return bus_reset_handling == ABORT_ON_BUS_RESET ? -EAGAIN : 0;
  92 }
  93
  94
  95 /**
  96  * cmp_connection_init - initializes a connection manager
  97  * @c: the connection manager to initialize
  98  * @unit: a unit of the target device
  99  * @ipcr_index: the index of the iPCR on the target device
 100  */
 101 int cmp_connection_init(struct cmp_connection *c,
 102                         struct fw_unit *unit,
 103                         unsigned int ipcr_index)
 104 {
 105         __be32 impr_be;
 106         u32 impr;
 107         int err;
 108
 109         err = snd_fw_transaction(unit, TCODE_READ_QUADLET_REQUEST,
 110                                  CSR_REGISTER_BASE + CSR_IMPR,
 111                                  &impr_be, 4);
 112         if (err < 0)
 113                 return err;
 114         impr = be32_to_cpu(impr_be);
 115
 116         if (ipcr_index >= (impr & IMPR_PLUGS_MASK))
 117                 return -EINVAL;
 118
 119         err = fw_iso_resources_init(&c->resources, unit);
 120         if (err < 0)
 121                 return err;
 122
 123         c->connected = false;
 124         mutex_init(&c->mutex);
 125         c->last_pcr_value = cpu_to_be32(0x80000000);
 126         c->pcr_index = ipcr_index;
 127         c->max_speed = (impr & IMPR_SPEED_MASK) >> IMPR_SPEED_SHIFT;
 128         if (c->max_speed == SCODE_BETA)
 129                 c->max_speed += (impr & IMPR_XSPEED_MASK) >> IMPR_XSPEED_SHIFT;
 130
 131         return 0;
 132 }
 133 EXPORT_SYMBOL(cmp_connection_init);
 134
 135 /**
 136  * cmp_connection_destroy - free connection manager resources
 137  * @c: the connection manager
 138  */
 139 void cmp_connection_destroy(struct cmp_connection *c)
 140 {
 141         WARN_ON(c->connected);
 142         mutex_destroy(&c->mutex);
 143         fw_iso_resources_destroy(&c->resources);
 144 }
 145 EXPORT_SYMBOL(cmp_connection_destroy);
 146
 147
 148 static __be32 ipcr_set_modify(struct cmp_connection *c, __be32 ipcr)
 149 {
 150         ipcr &= ~cpu_to_be32(IPCR_BCAST_CONN |
 151                              IPCR_P2P_CONN_MASK |
 152                              IPCR_CHANNEL_MASK);
 153         ipcr |= cpu_to_be32(1 << IPCR_P2P_CONN_SHIFT);
 154         ipcr |= cpu_to_be32(c->resources.channel << IPCR_CHANNEL_SHIFT);
 155
 156         return ipcr;
 157 }
 158
 159 static int ipcr_set_check(struct cmp_connection *c, __be32 ipcr)
 160 {
 161         if (ipcr & cpu_to_be32(IPCR_BCAST_CONN |
 162                                IPCR_P2P_CONN_MASK)) {
 163                 cmp_error(c, "plug is already in use\n");
 164                 return -EBUSY;
 165         }
 166         if (!(ipcr & cpu_to_be32(IPCR_ONLINE))) {
 167                 cmp_error(c, "plug is not on-line\n");
 168                 return -ECONNREFUSED;
 169         }
 170
 171         return 0;
 172 }
 173
 174 /**
 175  * cmp_connection_establish - establish a connection to the target
 176  * @c: the connection manager
 177  * @max_payload_bytes: the amount of data (including CIP headers) per packet
 178  *
 179  * This function establishes a point-to-point connection from the local
 180  * computer to the target by allocating isochronous resources (channel and
 181  * bandwidth) and setting the target's input plug control register.  When this
 182  * function succeeds, the caller is responsible for starting transmitting
 183  * packets.
 184  */
 185 int cmp_connection_establish(struct cmp_connection *c,
 186                              unsigned int max_payload_bytes)
 187 {
 188         int err;
 189
 190         if (WARN_ON(c->connected))
 191                 return -EISCONN;
 192
 193         c->speed = min(c->max_speed,
 194                        fw_parent_device(c->resources.unit)->max_speed);
 195
 196         mutex_lock(&c->mutex);
 197
 198 retry_after_bus_reset:
 199         err = fw_iso_resources_allocate(&c->resources,
 200                                         max_payload_bytes, c->speed);
 201         if (err < 0)
 202                 goto err_mutex;
 203
 204         err = pcr_modify(c, ipcr_set_modify, ipcr_set_check,
 205                          ABORT_ON_BUS_RESET);
 206         if (err == -EAGAIN) {
 207                 fw_iso_resources_free(&c->resources);
 208                 goto retry_after_bus_reset;
 209         }
 210         if (err < 0)
 211                 goto err_resources;
 212
 213         c->connected = true;
 214
 215         mutex_unlock(&c->mutex);
 216
 217         return 0;
 218
 219 err_resources:
 220         fw_iso_resources_free(&c->resources);
 221 err_mutex:
 222         mutex_unlock(&c->mutex);
 223
 224         return err;
 225 }
 226 EXPORT_SYMBOL(cmp_connection_establish);
 227
 228 /**
 229  * cmp_connection_update - update the connection after a bus reset
 230  * @c: the connection manager
 231  *
 232  * This function must be called from the driver's .update handler to reestablish
 233  * any connection that might have been active.
 234  *
 235  * Returns zero on success, or a negative error code.  On an error, the
 236  * connection is broken and the caller must stop transmitting iso packets.
 237  */
 238 int cmp_connection_update(struct cmp_connection *c)
 239 {
 240         int err;
 241
 242         mutex_lock(&c->mutex);
 243
 244         if (!c->connected) {
 245                 mutex_unlock(&c->mutex);
 246                 return 0;
 247         }
 248
 249         err = fw_iso_resources_update(&c->resources);
 250         if (err < 0)
 251                 goto err_unconnect;
 252
 253         err = pcr_modify(c, ipcr_set_modify, ipcr_set_check,
 254                          SUCCEED_ON_BUS_RESET);
 255         if (err < 0)
 256                 goto err_resources;
 257
 258         mutex_unlock(&c->mutex);
 259
 260         return 0;
 261
 262 err_resources:
 263         fw_iso_resources_free(&c->resources);
 264 err_unconnect:
 265         c->connected = false;
 266         mutex_unlock(&c->mutex);
 267
 268         return err;
 269 }
 270 EXPORT_SYMBOL(cmp_connection_update);
 271
 272
 273 static __be32 ipcr_break_modify(struct cmp_connection *c, __be32 ipcr)
 274 {
 275         return ipcr & ~cpu_to_be32(IPCR_BCAST_CONN | IPCR_P2P_CONN_MASK);
 276 }
 277
 278 /**
 279  * cmp_connection_break - break the connection to the target
 280  * @c: the connection manager
 281  *
 282  * This function deactives the connection in the target's input plug control
 283  * register, and frees the isochronous resources of the connection.  Before
 284  * calling this function, the caller should cease transmitting packets.
 285  */
 286 void cmp_connection_break(struct cmp_connection *c)
 287 {
 288         int err;
 289
 290         mutex_lock(&c->mutex);
 291
 292         if (!c->connected) {
 293                 mutex_unlock(&c->mutex);
 294                 return;
 295         }
 296
 297         err = pcr_modify(c, ipcr_break_modify, NULL, SUCCEED_ON_BUS_RESET);
 298         if (err < 0)
 299                 cmp_error(c, "plug is still connected\n");
 300
 301         fw_iso_resources_free(&c->resources);
 302
 303         c->connected = false;
 304
 305         mutex_unlock(&c->mutex);
 306 }
 307 EXPORT_SYMBOL(cmp_connection_break);