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kfifo: add kfifo_dma_out_prepare_mapped()
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When the kfifo buffer is already dma-mapped, one cannot use the kfifo
API to fill in an SG list.

Add kfifo_dma_in_prepare_mapped() which allows exactly this. A mapped
dma_addr_t is passed and it is filled into provided sgl too. Including
the dma_len.

Signed-off-by: Jiri Slaby (SUSE) <jirislaby@kernel.org>
Cc: Stefani Seibold <stefani@seibold.net>
Cc: Andrew Morton <akpm@linux-foundation.org>
Link: https://lore.kernel.org/r/20240405060826.2521-8-jirislaby@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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Jiri Slaby (SUSE) authored and Greg Kroah-Hartman committed Apr 9, 2024
1 parent fea0dde commit d52b761
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Showing 2 changed files with 47 additions and 24 deletions.
37 changes: 25 additions & 12 deletions include/linux/kfifo.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -36,6 +36,7 @@
* to lock the reader.
*/

#include <linux/dma-mapping.h>
#include <linux/kernel.h>
#include <linux/spinlock.h>
#include <linux/stddef.h>
Expand Down Expand Up @@ -709,19 +710,20 @@ __kfifo_int_must_check_helper( \
)

/**
* kfifo_dma_in_prepare - setup a scatterlist for DMA input
* kfifo_dma_in_prepare_mapped - setup a scatterlist for DMA input
* @fifo: address of the fifo to be used
* @sgl: pointer to the scatterlist array
* @nents: number of entries in the scatterlist array
* @len: number of elements to transfer
* @dma: mapped dma address to fill into @sgl
*
* This macro fills a scatterlist for DMA input.
* It returns the number entries in the scatterlist array.
*
* Note that with only one concurrent reader and one concurrent
* writer, you don't need extra locking to use these macros.
*/
#define kfifo_dma_in_prepare(fifo, sgl, nents, len) \
#define kfifo_dma_in_prepare_mapped(fifo, sgl, nents, len, dma) \
({ \
typeof((fifo) + 1) __tmp = (fifo); \
struct scatterlist *__sgl = (sgl); \
Expand All @@ -730,10 +732,14 @@ __kfifo_int_must_check_helper( \
const size_t __recsize = sizeof(*__tmp->rectype); \
struct __kfifo *__kfifo = &__tmp->kfifo; \
(__recsize) ? \
__kfifo_dma_in_prepare_r(__kfifo, __sgl, __nents, __len, __recsize) : \
__kfifo_dma_in_prepare(__kfifo, __sgl, __nents, __len); \
__kfifo_dma_in_prepare_r(__kfifo, __sgl, __nents, __len, __recsize, \
dma) : \
__kfifo_dma_in_prepare(__kfifo, __sgl, __nents, __len, dma); \
})

#define kfifo_dma_in_prepare(fifo, sgl, nents, len) \
kfifo_dma_in_prepare_mapped(fifo, sgl, nents, len, DMA_MAPPING_ERROR)

/**
* kfifo_dma_in_finish - finish a DMA IN operation
* @fifo: address of the fifo to be used
Expand All @@ -758,11 +764,12 @@ __kfifo_int_must_check_helper( \
})

/**
* kfifo_dma_out_prepare - setup a scatterlist for DMA output
* kfifo_dma_out_prepare_mapped - setup a scatterlist for DMA output
* @fifo: address of the fifo to be used
* @sgl: pointer to the scatterlist array
* @nents: number of entries in the scatterlist array
* @len: number of elements to transfer
* @dma: mapped dma address to fill into @sgl
*
* This macro fills a scatterlist for DMA output which at most @len bytes
* to transfer.
Expand All @@ -772,7 +779,7 @@ __kfifo_int_must_check_helper( \
* Note that with only one concurrent reader and one concurrent
* writer, you don't need extra locking to use these macros.
*/
#define kfifo_dma_out_prepare(fifo, sgl, nents, len) \
#define kfifo_dma_out_prepare_mapped(fifo, sgl, nents, len, dma) \
({ \
typeof((fifo) + 1) __tmp = (fifo); \
struct scatterlist *__sgl = (sgl); \
Expand All @@ -781,10 +788,14 @@ __kfifo_int_must_check_helper( \
const size_t __recsize = sizeof(*__tmp->rectype); \
struct __kfifo *__kfifo = &__tmp->kfifo; \
(__recsize) ? \
__kfifo_dma_out_prepare_r(__kfifo, __sgl, __nents, __len, __recsize) : \
__kfifo_dma_out_prepare(__kfifo, __sgl, __nents, __len); \
__kfifo_dma_out_prepare_r(__kfifo, __sgl, __nents, __len, __recsize, \
dma) : \
__kfifo_dma_out_prepare(__kfifo, __sgl, __nents, __len, dma); \
})

#define kfifo_dma_out_prepare(fifo, sgl, nents, len) \
kfifo_dma_out_prepare_mapped(fifo, sgl, nents, len, DMA_MAPPING_ERROR)

/**
* kfifo_dma_out_finish - finish a DMA OUT operation
* @fifo: address of the fifo to be used
Expand Down Expand Up @@ -905,10 +916,10 @@ extern int __kfifo_to_user(struct __kfifo *fifo,
void __user *to, unsigned long len, unsigned int *copied);

extern unsigned int __kfifo_dma_in_prepare(struct __kfifo *fifo,
struct scatterlist *sgl, int nents, unsigned int len);
struct scatterlist *sgl, int nents, unsigned int len, dma_addr_t dma);

extern unsigned int __kfifo_dma_out_prepare(struct __kfifo *fifo,
struct scatterlist *sgl, int nents, unsigned int len);
struct scatterlist *sgl, int nents, unsigned int len, dma_addr_t dma);

extern unsigned int __kfifo_out_peek(struct __kfifo *fifo,
void *buf, unsigned int len);
Expand All @@ -930,13 +941,15 @@ extern int __kfifo_to_user_r(struct __kfifo *fifo, void __user *to,
unsigned long len, unsigned int *copied, size_t recsize);

extern unsigned int __kfifo_dma_in_prepare_r(struct __kfifo *fifo,
struct scatterlist *sgl, int nents, unsigned int len, size_t recsize);
struct scatterlist *sgl, int nents, unsigned int len, size_t recsize,
dma_addr_t dma);

extern void __kfifo_dma_in_finish_r(struct __kfifo *fifo,
unsigned int len, size_t recsize);

extern unsigned int __kfifo_dma_out_prepare_r(struct __kfifo *fifo,
struct scatterlist *sgl, int nents, unsigned int len, size_t recsize);
struct scatterlist *sgl, int nents, unsigned int len, size_t recsize,
dma_addr_t dma);

extern unsigned int __kfifo_len_r(struct __kfifo *fifo, size_t recsize);

Expand Down
34 changes: 22 additions & 12 deletions lib/kfifo.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -6,6 +6,7 @@
*/

#include <linux/kernel.h>
#include <linux/dma-mapping.h>
#include <linux/export.h>
#include <linux/slab.h>
#include <linux/err.h>
Expand Down Expand Up @@ -307,7 +308,7 @@ EXPORT_SYMBOL(__kfifo_to_user);

static unsigned int setup_sgl_buf(struct __kfifo *fifo, struct scatterlist *sgl,
unsigned int data_offset, int nents,
unsigned int len)
unsigned int len, dma_addr_t dma)
{
const void *buf = fifo->data + data_offset;

Expand All @@ -316,11 +317,16 @@ static unsigned int setup_sgl_buf(struct __kfifo *fifo, struct scatterlist *sgl,

sg_set_buf(sgl, buf, len);

if (dma != DMA_MAPPING_ERROR) {
sg_dma_address(sgl) = dma + data_offset;
sg_dma_len(sgl) = len;
}

return 1;
}

static unsigned int setup_sgl(struct __kfifo *fifo, struct scatterlist *sgl,
int nents, unsigned int len, unsigned int off)
int nents, unsigned int len, unsigned int off, dma_addr_t dma)
{
unsigned int size = fifo->mask + 1;
unsigned int esize = fifo->esize;
Expand All @@ -335,35 +341,37 @@ static unsigned int setup_sgl(struct __kfifo *fifo, struct scatterlist *sgl,
}
len_to_end = min(len, size - off);

n = setup_sgl_buf(fifo, sgl, off, nents, len_to_end);
n += setup_sgl_buf(fifo, sgl + n, 0, nents - n, len - len_to_end);
n = setup_sgl_buf(fifo, sgl, off, nents, len_to_end, dma);
n += setup_sgl_buf(fifo, sgl + n, 0, nents - n, len - len_to_end, dma);

return n;
}

unsigned int __kfifo_dma_in_prepare(struct __kfifo *fifo,
struct scatterlist *sgl, int nents, unsigned int len)
struct scatterlist *sgl, int nents, unsigned int len,
dma_addr_t dma)
{
unsigned int l;

l = kfifo_unused(fifo);
if (len > l)
len = l;

return setup_sgl(fifo, sgl, nents, len, fifo->in);
return setup_sgl(fifo, sgl, nents, len, fifo->in, dma);
}
EXPORT_SYMBOL(__kfifo_dma_in_prepare);

unsigned int __kfifo_dma_out_prepare(struct __kfifo *fifo,
struct scatterlist *sgl, int nents, unsigned int len)
struct scatterlist *sgl, int nents, unsigned int len,
dma_addr_t dma)
{
unsigned int l;

l = fifo->in - fifo->out;
if (len > l)
len = l;

return setup_sgl(fifo, sgl, nents, len, fifo->out);
return setup_sgl(fifo, sgl, nents, len, fifo->out, dma);
}
EXPORT_SYMBOL(__kfifo_dma_out_prepare);

Expand Down Expand Up @@ -547,7 +555,8 @@ int __kfifo_to_user_r(struct __kfifo *fifo, void __user *to,
EXPORT_SYMBOL(__kfifo_to_user_r);

unsigned int __kfifo_dma_in_prepare_r(struct __kfifo *fifo,
struct scatterlist *sgl, int nents, unsigned int len, size_t recsize)
struct scatterlist *sgl, int nents, unsigned int len, size_t recsize,
dma_addr_t dma)
{
BUG_ON(!nents);

Expand All @@ -556,7 +565,7 @@ unsigned int __kfifo_dma_in_prepare_r(struct __kfifo *fifo,
if (len + recsize > kfifo_unused(fifo))
return 0;

return setup_sgl(fifo, sgl, nents, len, fifo->in + recsize);
return setup_sgl(fifo, sgl, nents, len, fifo->in + recsize, dma);
}
EXPORT_SYMBOL(__kfifo_dma_in_prepare_r);

Expand All @@ -570,7 +579,8 @@ void __kfifo_dma_in_finish_r(struct __kfifo *fifo,
EXPORT_SYMBOL(__kfifo_dma_in_finish_r);

unsigned int __kfifo_dma_out_prepare_r(struct __kfifo *fifo,
struct scatterlist *sgl, int nents, unsigned int len, size_t recsize)
struct scatterlist *sgl, int nents, unsigned int len, size_t recsize,
dma_addr_t dma)
{
BUG_ON(!nents);

Expand All @@ -579,7 +589,7 @@ unsigned int __kfifo_dma_out_prepare_r(struct __kfifo *fifo,
if (len + recsize > fifo->in - fifo->out)
return 0;

return setup_sgl(fifo, sgl, nents, len, fifo->out + recsize);
return setup_sgl(fifo, sgl, nents, len, fifo->out + recsize, dma);
}
EXPORT_SYMBOL(__kfifo_dma_out_prepare_r);

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