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