diff options
| author | Guennadi Liakhovetski <g.liakhovetski@gmx.de> | 2011-01-21 16:56:42 +0100 |
|---|---|---|
| committer | Grant Likely <grant.likely@secretlab.ca> | 2011-01-21 10:02:35 -0700 |
| commit | 9dabb3f3269d042908bf1f4e685413c39cc8c373 (patch) | |
| tree | a6913470397af37729670966b9683aec48edb525 /drivers/spi | |
| parent | e2dbf5ebcc983b0349ab507bf7dd5562cf88dd24 (diff) | |
| download | linux-9dabb3f3269d042908bf1f4e685413c39cc8c373.tar.bz2 | |
spi/spi_sh_msiof: consolidate data in 8-bit mode into 32-bit words
Instead of sending data 8 bits at a time in 8-bit SPI mode, swap bytes
and send and receive them 32 bits at a time. Tested with an SD-card,
with which this patch reduced the number of interrupts by 50%, when
reading 5MiB of data (there are also small service packets, the number
of interrupts, produced by 512-byte sectors should, of course, drop by
75%), and improved throughput by more than 40%.
Signed-off-by: Guennadi Liakhovetski <g.liakhovetski@gmx.de>
Signed-off-by: Grant Likely <grant.likely@secretlab.ca>
Diffstat (limited to 'drivers/spi')
| -rw-r--r-- | drivers/spi/spi_sh_msiof.c | 59 |
1 files changed, 59 insertions, 0 deletions
diff --git a/drivers/spi/spi_sh_msiof.c b/drivers/spi/spi_sh_msiof.c index d220cb287874..da6e42ec856e 100644 --- a/drivers/spi/spi_sh_msiof.c +++ b/drivers/spi/spi_sh_msiof.c @@ -267,6 +267,26 @@ static void sh_msiof_spi_write_fifo_32u(struct sh_msiof_spi_priv *p, sh_msiof_write(p, TFDR, get_unaligned(&buf_32[k]) << fs); } +static void sh_msiof_spi_write_fifo_s32(struct sh_msiof_spi_priv *p, + const void *tx_buf, int words, int fs) +{ + const u32 *buf_32 = tx_buf; + int k; + + for (k = 0; k < words; k++) + sh_msiof_write(p, TFDR, swab32(buf_32[k] << fs)); +} + +static void sh_msiof_spi_write_fifo_s32u(struct sh_msiof_spi_priv *p, + const void *tx_buf, int words, int fs) +{ + const u32 *buf_32 = tx_buf; + int k; + + for (k = 0; k < words; k++) + sh_msiof_write(p, TFDR, swab32(get_unaligned(&buf_32[k]) << fs)); +} + static void sh_msiof_spi_read_fifo_8(struct sh_msiof_spi_priv *p, void *rx_buf, int words, int fs) { @@ -317,6 +337,26 @@ static void sh_msiof_spi_read_fifo_32u(struct sh_msiof_spi_priv *p, put_unaligned(sh_msiof_read(p, RFDR) >> fs, &buf_32[k]); } +static void sh_msiof_spi_read_fifo_s32(struct sh_msiof_spi_priv *p, + void *rx_buf, int words, int fs) +{ + u32 *buf_32 = rx_buf; + int k; + + for (k = 0; k < words; k++) + buf_32[k] = swab32(sh_msiof_read(p, RFDR) >> fs); +} + +static void sh_msiof_spi_read_fifo_s32u(struct sh_msiof_spi_priv *p, + void *rx_buf, int words, int fs) +{ + u32 *buf_32 = rx_buf; + int k; + + for (k = 0; k < words; k++) + put_unaligned(swab32(sh_msiof_read(p, RFDR) >> fs), &buf_32[k]); +} + static int sh_msiof_spi_bits(struct spi_device *spi, struct spi_transfer *t) { int bits; @@ -468,9 +508,17 @@ static int sh_msiof_spi_txrx(struct spi_device *spi, struct spi_transfer *t) int bytes_done; int words; int n; + bool swab; bits = sh_msiof_spi_bits(spi, t); + if (bits <= 8 && t->len > 15 && !(t->len & 3)) { + bits = 32; + swab = true; + } else { + swab = false; + } + /* setup bytes per word and fifo read/write functions */ if (bits <= 8) { bytes_per_word = 1; @@ -487,6 +535,17 @@ static int sh_msiof_spi_txrx(struct spi_device *spi, struct spi_transfer *t) rx_fifo = sh_msiof_spi_read_fifo_16u; else rx_fifo = sh_msiof_spi_read_fifo_16; + } else if (swab) { + bytes_per_word = 4; + if ((unsigned long)t->tx_buf & 0x03) + tx_fifo = sh_msiof_spi_write_fifo_s32u; + else + tx_fifo = sh_msiof_spi_write_fifo_s32; + + if ((unsigned long)t->rx_buf & 0x03) + rx_fifo = sh_msiof_spi_read_fifo_s32u; + else + rx_fifo = sh_msiof_spi_read_fifo_s32; } else { bytes_per_word = 4; if ((unsigned long)t->tx_buf & 0x03) |