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 static void async_midi_port_callback(struct fw_card *card, int rcode, 71 void *data, size_t length, 72 void *callback_data) 73 { 74 struct snd_fw_async_midi_port *port = callback_data; 75 struct snd_rawmidi_substream *substream = ACCESS_ONCE(port->substream); 76 77 /* This port is closed. */ 78 if (substream == NULL) 79 return; 80 81 if (rcode == RCODE_COMPLETE) 82 snd_rawmidi_transmit_ack(substream, port->consume_bytes); 83 else if (!rcode_is_permanent_error(rcode)) 84 /* To start next transaction immediately for recovery. */ 85 port->next_ktime = ktime_set(0, 0); 86 else 87 /* Don't continue processing. */ 88 port->error = true; 89 90 port->idling = true; 91 92 if (!snd_rawmidi_transmit_empty(substream)) 93 schedule_work(&port->work); 94 } 95 96 static void midi_port_work(struct work_struct *work) 97 { 98 struct snd_fw_async_midi_port *port = 99 container_of(work, struct snd_fw_async_midi_port, work); 100 struct snd_rawmidi_substream *substream = ACCESS_ONCE(port->substream); 101 int generation; 102 int type; 103 104 /* Under transacting or error state. */ 105 if (!port->idling || port->error) 106 return; 107 108 /* Nothing to do. */ 109 if (substream == NULL || snd_rawmidi_transmit_empty(substream)) 110 return; 111 112 /* Do it in next chance. */ 113 if (ktime_after(port->next_ktime, ktime_get())) { 114 schedule_work(&port->work); 115 return; 116 } 117 118 /* 119 * Fill the buffer. The callee must use snd_rawmidi_transmit_peek(). 120 * Later, snd_rawmidi_transmit_ack() is called. 121 */ 122 memset(port->buf, 0, port->len); 123 port->consume_bytes = port->fill(substream, port->buf); 124 if (port->consume_bytes <= 0) { 125 /* Do it in next chance, immediately. */ 126 if (port->consume_bytes == 0) { 127 port->next_ktime = ktime_set(0, 0); 128 schedule_work(&port->work); 129 } else { 130 /* Fatal error. */ 131 port->error = true; 132 } 133 return; 134 } 135 136 /* Calculate type of transaction. */ 137 if (port->len == 4) 138 type = TCODE_WRITE_QUADLET_REQUEST; 139 else 140 type = TCODE_WRITE_BLOCK_REQUEST; 141 142 /* Set interval to next transaction. */ 143 port->next_ktime = ktime_add_ns(ktime_get(), 144 port->consume_bytes * 8 * NSEC_PER_SEC / 31250); 145 146 /* Start this transaction. */ 147 port->idling = false; 148 149 /* 150 * In Linux FireWire core, when generation is updated with memory 151 * barrier, node id has already been updated. In this module, After 152 * this smp_rmb(), load/store instructions to memory are completed. 153 * Thus, both of generation and node id are available with recent 154 * values. This is a light-serialization solution to handle bus reset 155 * events on IEEE 1394 bus. 156 */ 157 generation = port->parent->generation; 158 smp_rmb(); 159 160 fw_send_request(port->parent->card, &port->transaction, type, 161 port->parent->node_id, generation, 162 port->parent->max_speed, port->addr, 163 port->buf, port->len, async_midi_port_callback, 164 port); 165 } 166 167 /** 168 * snd_fw_async_midi_port_init - initialize asynchronous MIDI port structure 169 * @port: the asynchronous MIDI port to initialize 170 * @unit: the target of the asynchronous transaction 171 * @addr: the address to which transactions are transferred 172 * @len: the length of transaction 173 * @fill: the callback function to fill given buffer, and returns the 174 * number of consumed bytes for MIDI message. 175 * 176 */ 177 int snd_fw_async_midi_port_init(struct snd_fw_async_midi_port *port, 178 struct fw_unit *unit, u64 addr, unsigned int len, 179 snd_fw_async_midi_port_fill fill) 180 { 181 port->len = DIV_ROUND_UP(len, 4) * 4; 182 port->buf = kzalloc(port->len, GFP_KERNEL); 183 if (port->buf == NULL) 184 return -ENOMEM; 185 186 port->parent = fw_parent_device(unit); 187 port->addr = addr; 188 port->fill = fill; 189 port->idling = true; 190 port->next_ktime = ktime_set(0, 0); 191 port->error = false; 192 193 INIT_WORK(&port->work, midi_port_work); 194 195 return 0; 196 } 197 EXPORT_SYMBOL(snd_fw_async_midi_port_init); 198 199 /** 200 * snd_fw_async_midi_port_destroy - free asynchronous MIDI port structure 201 * @port: the asynchronous MIDI port structure 202 */ 203 void snd_fw_async_midi_port_destroy(struct snd_fw_async_midi_port *port) 204 { 205 snd_fw_async_midi_port_finish(port); 206 cancel_work_sync(&port->work); 207 kfree(port->buf); 208 } 209 EXPORT_SYMBOL(snd_fw_async_midi_port_destroy); 210 211 MODULE_DESCRIPTION("FireWire audio helper functions"); 212 MODULE_AUTHOR("Clemens Ladisch <clemens@ladisch.de>"); 213 MODULE_LICENSE("GPL v2"); 214