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spi: Add support to handle kmap'd buffers in spi_map_buf() 

JFFS2 FS might sometime provide kmap'd buffers as destination
buffers to read data from flash. Update spi_map_buf() function to
generate sg_list for such buffers, so that SPI controllers drivers can
use DMA to read data into such buffers.

Signed-off-by: Vignesh R <vigneshr@ti.com>
Signed-off-by: Mark Brown <broonie@kernel.org>
This commit is contained in:
Vignesh R 2016-08-17 15:22:36 +05:30 committed by Mark Brown
parent 29b4817d40
commit b1b8153cf0
1 changed files with 14 additions and 3 deletions
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17
drivers/spi/spi.c
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@ -37,6 +37,7 @@
#include <linux/kthread.h>
#include <linux/ioport.h>
#include <linux/acpi.h>
#include <linux/highmem.h>
#define CREATE_TRACE_POINTS
#include <trace/events/spi.h>
@ -709,6 +710,13 @@ static int spi_map_buf(struct spi_master *master, struct device *dev,
{
const bool vmalloced_buf = is_vmalloc_addr(buf);
unsigned int max_seg_size = dma_get_max_seg_size(dev);
#ifdef CONFIG_HIGHMEM
const bool kmap_buf = ((unsigned long)buf >= PKMAP_BASE &&
(unsigned long)buf < (PKMAP_BASE +
(LAST_PKMAP * PAGE_SIZE)));
#else
const bool kmap_buf = false;
#endif
int desc_len;
int sgs;
struct page *vm_page;
@ -716,7 +724,7 @@ static int spi_map_buf(struct spi_master *master, struct device *dev,
size_t min;
int i, ret;
if (vmalloced_buf) {
if (vmalloced_buf || kmap_buf) {
desc_len = min_t(int, max_seg_size, PAGE_SIZE);
sgs = DIV_ROUND_UP(len + offset_in_page(buf), desc_len);
} else if (virt_addr_valid(buf)) {
@ -732,10 +740,13 @@ static int spi_map_buf(struct spi_master *master, struct device *dev,
for (i = 0; i < sgs; i++) {
if (vmalloced_buf) {
if (vmalloced_buf || kmap_buf) {
min = min_t(size_t,
len, desc_len - offset_in_page(buf));
vm_page = vmalloc_to_page(buf);
if (vmalloced_buf)
vm_page = vmalloc_to_page(buf);
else
vm_page = kmap_to_page(buf);
if (!vm_page) {
sg_free_table(sgt);
return -ENOMEM;