forked from mirrors/linux
615c164da0
Introduces a concept of external buffers, which is a mechanism for creating trace sinks that would receive trace data from MSC buffers and transfer it elsewhere. A external buffer can implement its own window allocation/deallocation if it has to. It must provide a callback that's used to notify it when a window fills up, so that it can then start a DMA transaction from that window 'elsewhere'. This window remains in a 'locked' state and won't be used for storing new trace data until the buffer 'unlocks' it with a provided API call, at which point the window can be used again for storing trace data. This relies on a functional "last block" interrupt, so not all versions of Trace Hub can use this feature, which does not reflect on existing users. Signed-off-by: Alexander Shishkin <alexander.shishkin@linux.intel.com> Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com> Link: https://lore.kernel.org/r/20190705141425.19894-2-alexander.shishkin@linux.intel.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
79 lines
2.4 KiB
C
79 lines
2.4 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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/*
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* Intel(R) Trace Hub data structures for implementing buffer sinks.
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*
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* Copyright (C) 2019 Intel Corporation.
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*/
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#ifndef _INTEL_TH_H_
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#define _INTEL_TH_H_
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#include <linux/scatterlist.h>
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/* MSC operating modes (MSC_MODE) */
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enum {
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MSC_MODE_SINGLE = 0,
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MSC_MODE_MULTI,
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MSC_MODE_EXI,
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MSC_MODE_DEBUG,
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};
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struct msu_buffer {
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const char *name;
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/*
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* ->assign() called when buffer 'mode' is set to this driver
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* (aka mode_store())
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* @device: struct device * of the msc
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* @mode: allows the driver to set HW mode (see the enum above)
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* Returns: a pointer to a private structure associated with this
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* msc or NULL in case of error. This private structure
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* will then be passed into all other callbacks.
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*/
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void *(*assign)(struct device *dev, int *mode);
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/* ->unassign(): some other mode is selected, clean up */
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void (*unassign)(void *priv);
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/*
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* ->alloc_window(): allocate memory for the window of a given
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* size
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* @sgt: pointer to sg_table, can be overridden by the buffer
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* driver, or kept intact
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* Returns: number of sg table entries <= number of pages;
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* 0 is treated as an allocation failure.
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*/
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int (*alloc_window)(void *priv, struct sg_table **sgt,
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size_t size);
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void (*free_window)(void *priv, struct sg_table *sgt);
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/* ->activate(): trace has started */
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void (*activate)(void *priv);
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/* ->deactivate(): trace is about to stop */
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void (*deactivate)(void *priv);
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/*
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* ->ready(): window @sgt is filled up to the last block OR
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* tracing is stopped by the user; this window contains
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* @bytes data. The window in question transitions into
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* the "LOCKED" state, indicating that it can't be used
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* by hardware. To clear this state and make the window
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* available to the hardware again, call
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* intel_th_msc_window_unlock().
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*/
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int (*ready)(void *priv, struct sg_table *sgt, size_t bytes);
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};
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int intel_th_msu_buffer_register(const struct msu_buffer *mbuf,
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struct module *owner);
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void intel_th_msu_buffer_unregister(const struct msu_buffer *mbuf);
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void intel_th_msc_window_unlock(struct device *dev, struct sg_table *sgt);
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#define module_intel_th_msu_buffer(__buffer) \
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static int __init __buffer##_init(void) \
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{ \
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return intel_th_msu_buffer_register(&(__buffer), THIS_MODULE); \
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} \
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module_init(__buffer##_init); \
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static void __exit __buffer##_exit(void) \
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{ \
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intel_th_msu_buffer_unregister(&(__buffer)); \
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} \
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module_exit(__buffer##_exit);
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#endif /* _INTEL_TH_H_ */
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