| 1 | |
| 2 | |
| 3 | * miscellaneous helper functions
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| 4 | *
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| 5 | * Copyright (c) Clemens Ladisch <[email protected]>
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| 6 |
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| 7 |
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| 8 | #include <linux/delay.h>
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| 9 | #include <linux/device.h>
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| 10 | #include <linux/firewire.h>
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| 11 | #include <linux/module.h>
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| 12 | #include <linux/slab.h>
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| 13 | #include "lib.h"
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| 14 |
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| 15 | #define ERROR_RETRY_DELAY_MS 20
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| 16 |
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| 17 | |
| 18 | * snd_fw_transaction - send a request and wait for its completion
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| 19 | * @unit: the driver's unit on the target device
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| 20 | * @tcode: the transaction code
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| 21 | * @offset: the address in the target's address space
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| 22 | * @buffer: input/output data
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| 23 | * @length: length of @buffer
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| 24 | * @flags: use %FW_FIXED_GENERATION and add the generation value to attempt the
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| 25 | * request only in that generation; use %FW_QUIET to suppress error
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| 26 | * messages
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| 27 | *
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| 28 | * Submits an asynchronous request to the target device, and waits for the
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| 29 | * response. The node ID and the current generation are derived from @unit.
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| 30 | * On a bus reset or an error, the transaction is retried a few times.
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| 31 | * Returns zero on success, or a negative error code.
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| 32 |
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| 33 | int snd_fw_transaction(struct fw_unit *unit, int tcode,
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| 34 | u64 offset, void *buffer, size_t length,
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| 35 | unsigned int flags)
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| 36 | {
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| 37 | struct fw_device *device = fw_parent_device(unit);
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| 38 | int generation, rcode, tries = 0;
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| 39 |
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| 40 | generation = flags & FW_GENERATION_MASK;
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| 41 | for (;;) {
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| 42 | if (!(flags & FW_FIXED_GENERATION)) {
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| 43 | generation = device->generation;
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| 44 | smp_rmb();
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| 45 | }
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| 46 | rcode = fw_run_transaction(device->card, tcode,
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| 47 | device->node_id, generation,
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| 48 | device->max_speed, offset,
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| 49 | buffer, length);
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| 50 |
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| 51 | if (rcode == RCODE_COMPLETE)
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| 52 | return 0;
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| 53 |
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| 54 | if (rcode == RCODE_GENERATION && (flags & FW_FIXED_GENERATION))
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| 55 | return -EAGAIN;
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| 56 |
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| 57 | if (rcode_is_permanent_error(rcode) || ++tries >= 3) {
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| 58 | if (!(flags & FW_QUIET))
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| 59 | dev_err(&unit->device,
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| 60 | "transaction failed: %s\n",
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| 61 | fw_rcode_string(rcode));
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| 62 | return -EIO;
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| 63 | }
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| 64 |
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| 65 | msleep(ERROR_RETRY_DELAY_MS);
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| 66 | }
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| 67 | }
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| 68 | EXPORT_SYMBOL(snd_fw_transaction);
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| 69 |
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| 70 | MODULE_DESCRIPTION("FireWire audio helper functions");
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| 71 | MODULE_AUTHOR("Clemens Ladisch <[email protected]>");
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| 72 | MODULE_LICENSE("GPL");
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