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72 lines
2.1 KiB
72 lines
2.1 KiB
// SPDX-License-Identifier: GPL-2.0-only |
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/* |
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* miscellaneous helper functions |
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* |
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* Copyright (c) Clemens Ladisch <[email protected]> |
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*/ |
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#include <linux/delay.h> |
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#include <linux/device.h> |
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#include <linux/firewire.h> |
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#include <linux/module.h> |
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#include <linux/slab.h> |
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#include "lib.h" |
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#define ERROR_RETRY_DELAY_MS 20 |
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/** |
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* snd_fw_transaction - send a request and wait for its completion |
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* @unit: the driver's unit on the target device |
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* @tcode: the transaction code |
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* @offset: the address in the target's address space |
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* @buffer: input/output data |
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* @length: length of @buffer |
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* @flags: use %FW_FIXED_GENERATION and add the generation value to attempt the |
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* request only in that generation; use %FW_QUIET to suppress error |
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* messages |
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* |
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* Submits an asynchronous request to the target device, and waits for the |
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* response. The node ID and the current generation are derived from @unit. |
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* On a bus reset or an error, the transaction is retried a few times. |
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* Returns zero on success, or a negative error code. |
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*/ |
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int snd_fw_transaction(struct fw_unit *unit, int tcode, |
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u64 offset, void *buffer, size_t length, |
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unsigned int flags) |
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{ |
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struct fw_device *device = fw_parent_device(unit); |
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int generation, rcode, tries = 0; |
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generation = flags & FW_GENERATION_MASK; |
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for (;;) { |
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if (!(flags & FW_FIXED_GENERATION)) { |
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generation = device->generation; |
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smp_rmb(); /* node_id vs. generation */ |
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} |
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rcode = fw_run_transaction(device->card, tcode, |
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device->node_id, generation, |
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device->max_speed, offset, |
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buffer, length); |
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if (rcode == RCODE_COMPLETE) |
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return 0; |
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if (rcode == RCODE_GENERATION && (flags & FW_FIXED_GENERATION)) |
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return -EAGAIN; |
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if (rcode_is_permanent_error(rcode) || ++tries >= 3) { |
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if (!(flags & FW_QUIET)) |
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dev_err(&unit->device, |
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"transaction failed: %s\n", |
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fw_rcode_string(rcode)); |
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return -EIO; |
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} |
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msleep(ERROR_RETRY_DELAY_MS); |
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} |
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} |
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EXPORT_SYMBOL(snd_fw_transaction); |
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MODULE_DESCRIPTION("FireWire audio helper functions"); |
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MODULE_AUTHOR("Clemens Ladisch <[email protected]>"); |
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MODULE_LICENSE("GPL v2");
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