[PATCH v2 20/21] mmc: tifm_sd: Make use of the new sg_map helper function

Logan Gunthorpe
2017-04-25T18:21:07Z

This conversion is a bit complicated. We modiy the read_fifo,
write_fifo and copy_page functions to take a scatterlist instead of a
page. Thus we can use sg_map instead of kmap_atomic. There's a bit of
accounting that needed to be done for the offset for this to work.
(Seeing sg_map takes care of the offset but it's already added and
used earlier in the code.)

There's also no error path, so we use SG_MAP_MUST_NOT_FAIL which may
BUG_ON in certain cases in the future.

Signed-off-by: Logan Gunthorpe <logang@deltatee.com>
Cc: Alex Dubov <oakad@yahoo.com>
Cc: Ulf Hansson <ulf.hansson@linaro.org>
---
drivers/mmc/host/tifm_sd.c | 50 +++++++++++++++++++++++++++-------------------
1 file changed, 29 insertions(+), 21 deletions(-)

diff --git a/drivers/mmc/host/tifm_sd.c b/drivers/mmc/host/tifm_sd.c
index 93c4b40..e64345a 100644
--- a/drivers/mmc/host/tifm_sd.c
+++ b/drivers/mmc/host/tifm_sd.c
@@ -111,14 +111,16 @@ struct tifm_sd {
};

/* for some reason, host won't respond correctly to readw/writew */
-static void tifm_sd_read_fifo(struct tifm_sd *host, struct page *pg,
+static void tifm_sd_read_fifo(struct tifm_sd *host, struct scatterlist *sg,
unsigned int off, unsigned int cnt)
{
struct tifm_dev *sock = host->dev;
unsigned char *buf;
unsigned int pos = 0, val;

- buf = kmap_atomic(pg) + off;
+ buf = sg_map(sg, off - sg->offset,
+ SG_KMAP_ATOMIC | SG_MAP_MUST_NOT_FAIL);
+
if (host->cmd_flags & DATA_CARRY) {
buf[pos++] = host->bounce_buf_data[0];
host->cmd_flags &= ~DATA_CARRY;
@@ -134,17 +136,19 @@ static void tifm_sd_read_fifo(struct tifm_sd *host, struct page *pg,
}
buf[pos++] = (val >> 8) & 0xff;
}
- kunmap_atomic(buf - off);
+ sg_unmap(sg, buf, off - sg->offset, SG_KMAP_ATOMIC);
}

-static void tifm_sd_write_fifo(struct tifm_sd *host, struct page *pg,
+static void tifm_sd_write_fifo(struct tifm_sd *host, struct scatterlist *sg,
unsigned int off, unsigned int cnt)
{
struct tifm_dev *sock = host->dev;
unsigned char *buf;
unsigned int pos = 0, val;

- buf = kmap_atomic(pg) + off;
+ buf = sg_map(sg, off - sg->offset,
+ SG_KMAP_ATOMIC | SG_MAP_MUST_NOT_FAIL);
+
if (host->cmd_flags & DATA_CARRY) {
val = host->bounce_buf_data[0] | ((buf[pos++] << 8) & 0xff00);
writel(val, sock->addr + SOCK_MMCSD_DATA);
@@ -161,7 +165,7 @@ static void tifm_sd_write_fifo(struct tifm_sd *host, struct page *pg,
val |= (buf[pos++] << 8) & 0xff00;
writel(val, sock->addr + SOCK_MMCSD_DATA);
}
- kunmap_atomic(buf - off);
+ sg_unmap(sg, buf, off - sg->offset, SG_KMAP_ATOMIC);
}

static void tifm_sd_transfer_data(struct tifm_sd *host)
@@ -170,7 +174,6 @@ static void tifm_sd_transfer_data(struct tifm_sd *host)
struct scatterlist *sg = r_data->sg;
unsigned int off, cnt, t_size = TIFM_MMCSD_FIFO_SIZE * 2;
unsigned int p_off, p_cnt;
- struct page *pg;

if (host->sg_pos == host->sg_len)
return;
@@ -192,33 +195,39 @@ static void tifm_sd_transfer_data(struct tifm_sd *host)
}
off = sg[host->sg_pos].offset + host->block_pos;

- pg = nth_page(sg_page(&sg[host->sg_pos]), off >> PAGE_SHIFT);
p_off = offset_in_page(off);
p_cnt = PAGE_SIZE - p_off;
p_cnt = min(p_cnt, cnt);
p_cnt = min(p_cnt, t_size);

if (r_data->flags & MMC_DATA_READ)
- tifm_sd_read_fifo(host, pg, p_off, p_cnt);
+ tifm_sd_read_fifo(host, &sg[host->sg_pos], p_off,
+ p_cnt);
else if (r_data->flags & MMC_DATA_WRITE)
- tifm_sd_write_fifo(host, pg, p_off, p_cnt);
+ tifm_sd_write_fifo(host, &sg[host->sg_pos], p_off,
+ p_cnt);

t_size -= p_cnt;
host->block_pos += p_cnt;
}
}

-static void tifm_sd_copy_page(struct page *dst, unsigned int dst_off,
- struct page *src, unsigned int src_off,
+static void tifm_sd_copy_page(struct scatterlist *dst, unsigned int dst_off,
+ struct scatterlist *src, unsigned int src_off,
unsigned int count)
{
- unsigned char *src_buf = kmap_atomic(src) + src_off;
- unsigned char *dst_buf = kmap_atomic(dst) + dst_off;
+ unsigned char *src_buf, *dst_buf;
+
+ src_off -= src->offset;
+ dst_off -= dst->offset;
+
+ src_buf = sg_map(src, src_off, SG_KMAP_ATOMIC | SG_MAP_MUST_NOT_FAIL);
+ dst_buf = sg_map(dst, dst_off, SG_KMAP_ATOMIC | SG_MAP_MUST_NOT_FAIL);

memcpy(dst_buf, src_buf, count);

- kunmap_atomic(dst_buf - dst_off);
- kunmap_atomic(src_buf - src_off);
+ sg_unmap(dst, dst_buf, dst_off, SG_KMAP_ATOMIC);
+ sg_unmap(src, src_buf, src_off, SG_KMAP_ATOMIC);
}

static void tifm_sd_bounce_block(struct tifm_sd *host, struct mmc_data *r_data)
@@ -227,7 +236,6 @@ static void tifm_sd_bounce_block(struct tifm_sd *host, struct mmc_data *r_data)
unsigned int t_size = r_data->blksz;
unsigned int off, cnt;
unsigned int p_off, p_cnt;
- struct page *pg;

dev_dbg(&host->dev->dev, "bouncing block\n");
while (t_size) {
@@ -241,18 +249,18 @@ static void tifm_sd_bounce_block(struct tifm_sd *host, struct mmc_data *r_data)
}
off = sg[host->sg_pos].offset + host->block_pos;

- pg = nth_page(sg_page(&sg[host->sg_pos]), off >> PAGE_SHIFT);
p_off = offset_in_page(off);
p_cnt = PAGE_SIZE - p_off;
p_cnt = min(p_cnt, cnt);
p_cnt = min(p_cnt, t_size);

if (r_data->flags & MMC_DATA_WRITE)
- tifm_sd_copy_page(sg_page(&host->bounce_buf),
+ tifm_sd_copy_page(&host->bounce_buf,
r_data->blksz - t_size,
- pg, p_off, p_cnt);
+ &sg[host->sg_pos], p_off, p_cnt);
else if (r_data->flags & MMC_DATA_READ)
- tifm_sd_copy_page(pg, p_off, sg_page(&host->bounce_buf),
+ tifm_sd_copy_page(&sg[host->sg_pos], p_off,
+ &host->bounce_buf,
r_data->blksz - t_size, p_cnt);

t_size -= p_cnt;
--
2.1.4

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