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         __be32 old_arg, buffer[2];
  52         int err;
  53
  54         buffer[0] = c->last_pcr_value;
  55         for (;;) {
  56                 old_arg = buffer[0];
  57                 buffer[1] = modify(c, buffer[0]);
  58
  59                 err = snd_fw_transaction(
  60                                 c->resources.unit, TCODE_LOCK_COMPARE_SWAP,
  61                                 CSR_REGISTER_BASE + CSR_IPCR(c->pcr_index),
  62                                 buffer, 8,
  63                                 FW_FIXED_GENERATION | c->resources.generation);
  64
  65                 if (err < 0) {
  66                         if (err == -EAGAIN &&
  67                             bus_reset_handling == SUCCEED_ON_BUS_RESET)
  68                                 err = 0;
  69                         return err;
  70                 }
  71
  72                 if (buffer[0] == old_arg) /* success? */
  73                         break;
  74
  75                 if (check) {
  76                         err = check(c, buffer[0]);
  77                         if (err < 0)
  78                                 return err;
  79                 }
  80         }
  81         c->last_pcr_value = buffer[1];
  82
  83         return 0;
  84 }
  85
  86
  87 /**
  88  * cmp_connection_init - initializes a connection manager
  89  * @c: the connection manager to initialize
  90  * @unit: a unit of the target device
  91  * @ipcr_index: the index of the iPCR on the target device
  92  */
  93 int cmp_connection_init(struct cmp_connection *c,
  94                         struct fw_unit *unit,
  95                         unsigned int ipcr_index)
  96 {
  97         __be32 impr_be;
  98         u32 impr;
  99         int err;
 100
 101         err = snd_fw_transaction(unit, TCODE_READ_QUADLET_REQUEST,
 102                                  CSR_REGISTER_BASE + CSR_IMPR,
 103                                  &impr_be, 4, 0);
 104         if (err < 0)
 105                 return err;
 106         impr = be32_to_cpu(impr_be);
 107
 108         if (ipcr_index >= (impr & IMPR_PLUGS_MASK))
 109                 return -EINVAL;
 110
 111         err = fw_iso_resources_init(&c->resources, unit);
 112         if (err < 0)
 113                 return err;
 114
 115         c->connected = false;
 116         mutex_init(&c->mutex);
 117         c->last_pcr_value = cpu_to_be32(0x80000000);
 118         c->pcr_index = ipcr_index;
 119         c->max_speed = (impr & IMPR_SPEED_MASK) >> IMPR_SPEED_SHIFT;
 120         if (c->max_speed == SCODE_BETA)
 121                 c->max_speed += (impr & IMPR_XSPEED_MASK) >> IMPR_XSPEED_SHIFT;
 122
 123         return 0;
 124 }
 125 EXPORT_SYMBOL(cmp_connection_init);
 126
 127 /**
 128  * cmp_connection_destroy - free connection manager resources
 129  * @c: the connection manager
 130  */
 131 void cmp_connection_destroy(struct cmp_connection *c)
 132 {
 133         WARN_ON(c->connected);
 134         mutex_destroy(&c->mutex);
 135         fw_iso_resources_destroy(&c->resources);
 136 }
 137 EXPORT_SYMBOL(cmp_connection_destroy);
 138
 139
 140 static __be32 ipcr_set_modify(struct cmp_connection *c, __be32 ipcr)
 141 {
 142         ipcr &= ~cpu_to_be32(IPCR_BCAST_CONN |
 143                              IPCR_P2P_CONN_MASK |
 144                              IPCR_CHANNEL_MASK);
 145         ipcr |= cpu_to_be32(1 << IPCR_P2P_CONN_SHIFT);
 146         ipcr |= cpu_to_be32(c->resources.channel << IPCR_CHANNEL_SHIFT);
 147
 148         return ipcr;
 149 }
 150
 151 static int ipcr_set_check(struct cmp_connection *c, __be32 ipcr)
 152 {
 153         if (ipcr & cpu_to_be32(IPCR_BCAST_CONN |
 154                                IPCR_P2P_CONN_MASK)) {
 155                 cmp_error(c, "plug is already in use\n");
 156                 return -EBUSY;
 157         }
 158         if (!(ipcr & cpu_to_be32(IPCR_ONLINE))) {
 159                 cmp_error(c, "plug is not on-line\n");
 160                 return -ECONNREFUSED;
 161         }
 162
 163         return 0;
 164 }
 165
 166 /**
 167  * cmp_connection_establish - establish a connection to the target
 168  * @c: the connection manager
 169  * @max_payload_bytes: the amount of data (including CIP headers) per packet
 170  *
 171  * This function establishes a point-to-point connection from the local
 172  * computer to the target by allocating isochronous resources (channel and
 173  * bandwidth) and setting the target's input plug control register.  When this
 174  * function succeeds, the caller is responsible for starting transmitting
 175  * packets.
 176  */
 177 int cmp_connection_establish(struct cmp_connection *c,
 178                              unsigned int max_payload_bytes)
 179 {
 180         int err;
 181
 182         if (WARN_ON(c->connected))
 183                 return -EISCONN;
 184
 185         c->speed = min(c->max_speed,
 186                        fw_parent_device(c->resources.unit)->max_speed);
 187
 188         mutex_lock(&c->mutex);
 189
 190 retry_after_bus_reset:
 191         err = fw_iso_resources_allocate(&c->resources,
 192                                         max_payload_bytes, c->speed);
 193         if (err < 0)
 194                 goto err_mutex;
 195
 196         err = pcr_modify(c, ipcr_set_modify, ipcr_set_check,
 197                          ABORT_ON_BUS_RESET);
 198         if (err == -EAGAIN) {
 199                 fw_iso_resources_free(&c->resources);
 200                 goto retry_after_bus_reset;
 201         }
 202         if (err < 0)
 203                 goto err_resources;
 204
 205         c->connected = true;
 206
 207         mutex_unlock(&c->mutex);
 208
 209         return 0;
 210
 211 err_resources:
 212         fw_iso_resources_free(&c->resources);
 213 err_mutex:
 214         mutex_unlock(&c->mutex);
 215
 216         return err;
 217 }
 218 EXPORT_SYMBOL(cmp_connection_establish);
 219
 220 /**
 221  * cmp_connection_update - update the connection after a bus reset
 222  * @c: the connection manager
 223  *
 224  * This function must be called from the driver's .update handler to reestablish
 225  * any connection that might have been active.
 226  *
 227  * Returns zero on success, or a negative error code.  On an error, the
 228  * connection is broken and the caller must stop transmitting iso packets.
 229  */
 230 int cmp_connection_update(struct cmp_connection *c)
 231 {
 232         int err;
 233
 234         mutex_lock(&c->mutex);
 235
 236         if (!c->connected) {
 237                 mutex_unlock(&c->mutex);
 238                 return 0;
 239         }
 240
 241         err = fw_iso_resources_update(&c->resources);
 242         if (err < 0)
 243                 goto err_unconnect;
 244
 245         err = pcr_modify(c, ipcr_set_modify, ipcr_set_check,
 246                          SUCCEED_ON_BUS_RESET);
 247         if (err < 0)
 248                 goto err_resources;
 249
 250         mutex_unlock(&c->mutex);
 251
 252         return 0;
 253
 254 err_resources:
 255         fw_iso_resources_free(&c->resources);
 256 err_unconnect:
 257         c->connected = false;
 258         mutex_unlock(&c->mutex);
 259
 260         return err;
 261 }
 262 EXPORT_SYMBOL(cmp_connection_update);
 263
 264
 265 static __be32 ipcr_break_modify(struct cmp_connection *c, __be32 ipcr)
 266 {
 267         return ipcr & ~cpu_to_be32(IPCR_BCAST_CONN | IPCR_P2P_CONN_MASK);
 268 }
 269
 270 /**
 271  * cmp_connection_break - break the connection to the target
 272  * @c: the connection manager
 273  *
 274  * This function deactives the connection in the target's input plug control
 275  * register, and frees the isochronous resources of the connection.  Before
 276  * calling this function, the caller should cease transmitting packets.
 277  */
 278 void cmp_connection_break(struct cmp_connection *c)
 279 {
 280         int err;
 281
 282         mutex_lock(&c->mutex);
 283
 284         if (!c->connected) {
 285                 mutex_unlock(&c->mutex);
 286                 return;
 287         }
 288
 289         err = pcr_modify(c, ipcr_break_modify, NULL, SUCCEED_ON_BUS_RESET);
 290         if (err < 0)
 291                 cmp_error(c, "plug is still connected\n");
 292
 293         fw_iso_resources_free(&c->resources);
 294
 295         c->connected = false;
 296
 297         mutex_unlock(&c->mutex);
 298 }
 299 EXPORT_SYMBOL(cmp_connection_break);