1 /* 2 * miscellaneous 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/delay.h> 9 #include <linux/device.h> 10 #include <linux/firewire.h> 11 #include <linux/module.h> 12 #include <linux/slab.h> 13 #include "lib.h" 14 15 #define ERROR_RETRY_DELAY_MS 20 16 17 /** 18 * snd_fw_transaction - send a request and wait for its completion 19 * @unit: the driver's unit on the target device 20 * @tcode: the transaction code 21 * @offset: the address in the target's address space 22 * @buffer: input/output data 23 * @length: length of @buffer 24 * @flags: use %FW_FIXED_GENERATION and add the generation value to attempt the 25 * request only in that generation; use %FW_QUIET to suppress error 26 * messages 27 * 28 * Submits an asynchronous request to the target device, and waits for the 29 * response. The node ID and the current generation are derived from @unit. 30 * On a bus reset or an error, the transaction is retried a few times. 31 * Returns zero on success, or a negative error code. 32 */ 33 int snd_fw_transaction(struct fw_unit *unit, int tcode, 34 u64 offset, void *buffer, size_t length, 35 unsigned int flags) 36 { 37 struct fw_device *device = fw_parent_device(unit); 38 int generation, rcode, tries = 0; 39 40 generation = flags & FW_GENERATION_MASK; 41 for (;;) { 42 if (!(flags & FW_FIXED_GENERATION)) { 43 generation = device->generation; 44 smp_rmb(); /* node_id vs. generation */ 45 } 46 rcode = fw_run_transaction(device->card, tcode, 47 device->node_id, generation, 48 device->max_speed, offset, 49 buffer, length); 50 51 if (rcode == RCODE_COMPLETE) 52 return 0; 53 54 if (rcode == RCODE_GENERATION && (flags & FW_FIXED_GENERATION)) 55 return -EAGAIN; 56 57 if (rcode_is_permanent_error(rcode) || ++tries >= 3) { 58 if (!(flags & FW_QUIET)) 59 dev_err(&unit->device, 60 "transaction failed: %s\n", 61 fw_rcode_string(rcode)); 62 return -EIO; 63 } 64 65 msleep(ERROR_RETRY_DELAY_MS); 66 } 67 } 68 EXPORT_SYMBOL(snd_fw_transaction); 69 70 #define PROBE_DELAY_MS (2 * MSEC_PER_SEC) 71 72 /** 73 * snd_fw_schedule_registration - schedule work for sound card registration 74 * @unit: an instance for unit on IEEE 1394 bus 75 * @dwork: delayed work with callback function 76 * 77 * This function is not designed for general purposes. When new unit is 78 * connected to IEEE 1394 bus, the bus is under bus-reset state because of 79 * topological change. In this state, units tend to fail both of asynchronous 80 * and isochronous communication. To avoid this problem, this function is used 81 * to postpone sound card registration after the state. The callers must 82 * set up instance of delayed work in advance. 83 */ 84 void snd_fw_schedule_registration(struct fw_unit *unit, 85 struct delayed_work *dwork) 86 { 87 u64 now, delay; 88 89 now = get_jiffies_64(); 90 delay = fw_parent_device(unit)->card->reset_jiffies 91 + msecs_to_jiffies(PROBE_DELAY_MS); 92 93 if (time_after64(delay, now)) 94 delay -= now; 95 else 96 delay = 0; 97 98 mod_delayed_work(system_wq, dwork, delay); 99 } 100 EXPORT_SYMBOL(snd_fw_schedule_registration); 101 102 static void async_midi_port_callback(struct fw_card *card, int rcode, 103 void *data, size_t length, 104 void *callback_data) 105 { 106 struct snd_fw_async_midi_port *port = callback_data; 107 struct snd_rawmidi_substream *substream = ACCESS_ONCE(port->substream); 108 109 /* This port is closed. */ 110 if (substream == NULL) 111 return; 112 113 if (rcode == RCODE_COMPLETE) 114 snd_rawmidi_transmit_ack(substream, port->consume_bytes); 115 else if (!rcode_is_permanent_error(rcode)) 116 /* To start next transaction immediately for recovery. */ 117 port->next_ktime = 0; 118 else 119 /* Don't continue processing. */ 120 port->error = true; 121 122 port->idling = true; 123 124 if (!snd_rawmidi_transmit_empty(substream)) 125 schedule_work(&port->work); 126 } 127 128 static void midi_port_work(struct work_struct *work) 129 { 130 struct snd_fw_async_midi_port *port = 131 container_of(work, struct snd_fw_async_midi_port, work); 132 struct snd_rawmidi_substream *substream = ACCESS_ONCE(port->substream); 133 int generation; 134 int type; 135 136 /* Under transacting or error state. */ 137 if (!port->idling || port->error) 138 return; 139 140 /* Nothing to do. */ 141 if (substream == NULL || snd_rawmidi_transmit_empty(substream)) 142 return; 143 144 /* Do it in next chance. */ 145 if (ktime_after(port->next_ktime, ktime_get())) { 146 schedule_work(&port->work); 147 return; 148 } 149 150 /* 151 * Fill the buffer. The callee must use snd_rawmidi_transmit_peek(). 152 * Later, snd_rawmidi_transmit_ack() is called. 153 */ 154 memset(port->buf, 0, port->len); 155 port->consume_bytes = port->fill(substream, port->buf); 156 if (port->consume_bytes <= 0) { 157 /* Do it in next chance, immediately. */ 158 if (port->consume_bytes == 0) { 159 port->next_ktime = 0; 160 schedule_work(&port->work); 161 } else { 162 /* Fatal error. */ 163 port->error = true; 164 } 165 return; 166 } 167 168 /* Calculate type of transaction. */ 169 if (port->len == 4) 170 type = TCODE_WRITE_QUADLET_REQUEST; 171 else 172 type = TCODE_WRITE_BLOCK_REQUEST; 173 174 /* Set interval to next transaction. */ 175 port->next_ktime = ktime_add_ns(ktime_get(), 176 port->consume_bytes * 8 * NSEC_PER_SEC / 31250); 177 178 /* Start this transaction. */ 179 port->idling = false; 180 181 /* 182 * In Linux FireWire core, when generation is updated with memory 183 * barrier, node id has already been updated. In this module, After 184 * this smp_rmb(), load/store instructions to memory are completed. 185 * Thus, both of generation and node id are available with recent 186 * values. This is a light-serialization solution to handle bus reset 187 * events on IEEE 1394 bus. 188 */ 189 generation = port->parent->generation; 190 smp_rmb(); 191 192 fw_send_request(port->parent->card, &port->transaction, type, 193 port->parent->node_id, generation, 194 port->parent->max_speed, port->addr, 195 port->buf, port->len, async_midi_port_callback, 196 port); 197 } 198 199 /** 200 * snd_fw_async_midi_port_init - initialize asynchronous MIDI port structure 201 * @port: the asynchronous MIDI port to initialize 202 * @unit: the target of the asynchronous transaction 203 * @addr: the address to which transactions are transferred 204 * @len: the length of transaction 205 * @fill: the callback function to fill given buffer, and returns the 206 * number of consumed bytes for MIDI message. 207 * 208 */ 209 int snd_fw_async_midi_port_init(struct snd_fw_async_midi_port *port, 210 struct fw_unit *unit, u64 addr, unsigned int len, 211 snd_fw_async_midi_port_fill fill) 212 { 213 port->len = DIV_ROUND_UP(len, 4) * 4; 214 port->buf = kzalloc(port->len, GFP_KERNEL); 215 if (port->buf == NULL) 216 return -ENOMEM; 217 218 port->parent = fw_parent_device(unit); 219 port->addr = addr; 220 port->fill = fill; 221 port->idling = true; 222 port->next_ktime = 0; 223 port->error = false; 224 225 INIT_WORK(&port->work, midi_port_work); 226 227 return 0; 228 } 229 EXPORT_SYMBOL(snd_fw_async_midi_port_init); 230 231 /** 232 * snd_fw_async_midi_port_destroy - free asynchronous MIDI port structure 233 * @port: the asynchronous MIDI port structure 234 */ 235 void snd_fw_async_midi_port_destroy(struct snd_fw_async_midi_port *port) 236 { 237 snd_fw_async_midi_port_finish(port); 238 cancel_work_sync(&port->work); 239 kfree(port->buf); 240 } 241 EXPORT_SYMBOL(snd_fw_async_midi_port_destroy); 242 243 MODULE_DESCRIPTION("FireWire audio helper functions"); 244 MODULE_AUTHOR("Clemens Ladisch <clemens@ladisch.de>"); 245 MODULE_LICENSE("GPL v2"); 246