spi/bitbang: add support for SPI_MASTER_NO_{TX, RX} modes

This patch adds a new flags argument to bitbang_txrx_be_cpha0 and
bitbang_txrx_be_cpha1 transfer functions. This enables support for
SPI_MASTER_NO_{TX,RX} transfer modes. The change should have no impact
on speed of the existing drivers. bitbank_txrx_* functions are usually
inlined into the drivers. When the argument is equal to constant zero,
the optimizer would be able to eliminate the dead code (flags checks)
easily. Tested on ARM and GCC 4.4.x and in all cases the checks were
eliminated in the inlined function.

Reviewed-by: Kyungmin Park <kyungmin.park@samsung.com>
Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
Acked-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Grant Likely <grant.likely@secretlab.ca>

diff --git a/drivers/spi/spi_bitbang_txrx.h b/drivers/spi/spi_bitbang_txrx.h
index fc033bbf9180dc1adbdd20e33b9375e4cfd14fbe..c16bf853c3eb3f3a0c7ab3c3c8731cc179d30a15 100644 (file)
--- a/drivers/spi/spi_bitbang_txrx.h
+++ b/drivers/spi/spi_bitbang_txrx.h
@@ -44,7 +44,7 @@
 
 static inline u32
 bitbang_txrx_be_cpha0(struct spi_device *spi,
-               unsigned nsecs, unsigned cpol,
+               unsigned nsecs, unsigned cpol, unsigned flags,
                u32 word, u8 bits)
 {
        /* if (cpol == 0) this is SPI_MODE_0; else this is SPI_MODE_2 */
@@ -53,7 +53,8 @@ bitbang_txrx_be_cpha0(struct spi_device *spi,
        for (word <<= (32 - bits); likely(bits); bits--) {
 
                /* setup MSB (to slave) on trailing edge */
-               setmosi(spi, word & (1 << 31));
+               if ((flags & SPI_MASTER_NO_TX) == 0)
+                       setmosi(spi, word & (1 << 31));
                spidelay(nsecs);        /* T(setup) */
 
                setsck(spi, !cpol);
@@ -61,7 +62,8 @@ bitbang_txrx_be_cpha0(struct spi_device *spi,
 
                /* sample MSB (from slave) on leading edge */
                word <<= 1;
-               word |= getmiso(spi);
+               if ((flags & SPI_MASTER_NO_RX) == 0)
+                       word |= getmiso(spi);
                setsck(spi, cpol);
        }
        return word;
@@ -69,7 +71,7 @@ bitbang_txrx_be_cpha0(struct spi_device *spi,
 
 static inline u32
 bitbang_txrx_be_cpha1(struct spi_device *spi,
-               unsigned nsecs, unsigned cpol,
+               unsigned nsecs, unsigned cpol, unsigned flags,
                u32 word, u8 bits)
 {
        /* if (cpol == 0) this is SPI_MODE_1; else this is SPI_MODE_3 */
@@ -79,7 +81,8 @@ bitbang_txrx_be_cpha1(struct spi_device *spi,
 
                /* setup MSB (to slave) on leading edge */
                setsck(spi, !cpol);
-               setmosi(spi, word & (1 << 31));
+               if ((flags & SPI_MASTER_NO_TX) == 0)
+                       setmosi(spi, word & (1 << 31));
                spidelay(nsecs); /* T(setup) */
 
                setsck(spi, cpol);
@@ -87,7 +90,8 @@ bitbang_txrx_be_cpha1(struct spi_device *spi,
 
                /* sample MSB (from slave) on trailing edge */
                word <<= 1;
-               word |= getmiso(spi);
+               if ((flags & SPI_MASTER_NO_RX) == 0)
+                       word |= getmiso(spi);
        }
        return word;
 }

diff --git a/drivers/spi/spi_butterfly.c b/drivers/spi/spi_butterfly.c
index 8b52812811110d5a1ff4835813a4f613c5713f0c..0d4ceba3b5900258c071c86ebd1ff02ad50a2cdf 100644 (file)
--- a/drivers/spi/spi_butterfly.c
+++ b/drivers/spi/spi_butterfly.c
@@ -156,7 +156,7 @@ butterfly_txrx_word_mode0(struct spi_device *spi,
                unsigned nsecs,
                u32 word, u8 bits)
 {
-       return bitbang_txrx_be_cpha0(spi, nsecs, 0, word, bits);
+       return bitbang_txrx_be_cpha0(spi, nsecs, 0, 0, word, bits);
 }
 
 /*----------------------------------------------------------------------*/

diff --git a/drivers/spi/spi_gpio.c b/drivers/spi/spi_gpio.c
index 7edbd5807e0eb05e1e72242d0e304c034c4ae11b..82b480cc9637939376bf3b4845ca3bc029d599a7 100644 (file)
--- a/drivers/spi/spi_gpio.c
+++ b/drivers/spi/spi_gpio.c
@@ -146,25 +146,25 @@ static inline int getmiso(const struct spi_device *spi)
 static u32 spi_gpio_txrx_word_mode0(struct spi_device *spi,
                unsigned nsecs, u32 word, u8 bits)
 {
-       return bitbang_txrx_be_cpha0(spi, nsecs, 0, word, bits);
+       return bitbang_txrx_be_cpha0(spi, nsecs, 0, 0, word, bits);
 }
 
 static u32 spi_gpio_txrx_word_mode1(struct spi_device *spi,
                unsigned nsecs, u32 word, u8 bits)
 {
-       return bitbang_txrx_be_cpha1(spi, nsecs, 0, word, bits);
+       return bitbang_txrx_be_cpha1(spi, nsecs, 0, 0, word, bits);
 }
 
 static u32 spi_gpio_txrx_word_mode2(struct spi_device *spi,
                unsigned nsecs, u32 word, u8 bits)
 {
-       return bitbang_txrx_be_cpha0(spi, nsecs, 1, word, bits);
+       return bitbang_txrx_be_cpha0(spi, nsecs, 1, 0, word, bits);
 }
 
 static u32 spi_gpio_txrx_word_mode3(struct spi_device *spi,
                unsigned nsecs, u32 word, u8 bits)
 {
-       return bitbang_txrx_be_cpha1(spi, nsecs, 1, word, bits);
+       return bitbang_txrx_be_cpha1(spi, nsecs, 1, 0, word, bits);
 }
 
 /*----------------------------------------------------------------------*/

diff --git a/drivers/spi/spi_lm70llp.c b/drivers/spi/spi_lm70llp.c
index 86fb7b5993db124a763fb6a3ad52a863f96fb450..7746a41ab6d6dd958f5cf75d8d01e090b76ca12d 100644 (file)
--- a/drivers/spi/spi_lm70llp.c
+++ b/drivers/spi/spi_lm70llp.c
@@ -191,7 +191,7 @@ static void lm70_chipselect(struct spi_device *spi, int value)
  */
 static u32 lm70_txrx(struct spi_device *spi, unsigned nsecs, u32 word, u8 bits)
 {
-       return bitbang_txrx_be_cpha0(spi, nsecs, 0, word, bits);
+       return bitbang_txrx_be_cpha0(spi, nsecs, 0, 0, word, bits);
 }
 
 static void spi_lm70llp_attach(struct parport *p)

diff --git a/drivers/spi/spi_s3c24xx_gpio.c b/drivers/spi/spi_s3c24xx_gpio.c
index 8979a75dbd7b5cc2d0c77459fcab43966f36c03e..be991359bf9282cde5eaaa0eaa7fb0316dcf0d76 100644 (file)
--- a/drivers/spi/spi_s3c24xx_gpio.c
+++ b/drivers/spi/spi_s3c24xx_gpio.c
@@ -64,25 +64,25 @@ static inline u32 getmiso(struct spi_device *dev)
 static u32 s3c2410_spigpio_txrx_mode0(struct spi_device *spi,
                                      unsigned nsecs, u32 word, u8 bits)
 {
-       return bitbang_txrx_be_cpha0(spi, nsecs, 0, word, bits);
+       return bitbang_txrx_be_cpha0(spi, nsecs, 0, 0, word, bits);
 }
 
 static u32 s3c2410_spigpio_txrx_mode1(struct spi_device *spi,
                                      unsigned nsecs, u32 word, u8 bits)
 {
-       return bitbang_txrx_be_cpha1(spi, nsecs, 0, word, bits);
+       return bitbang_txrx_be_cpha1(spi, nsecs, 0, 0, word, bits);
 }
 
 static u32 s3c2410_spigpio_txrx_mode2(struct spi_device *spi,
                                      unsigned nsecs, u32 word, u8 bits)
 {
-       return bitbang_txrx_be_cpha0(spi, nsecs, 1, word, bits);
+       return bitbang_txrx_be_cpha0(spi, nsecs, 1, 0, word, bits);
 }
 
 static u32 s3c2410_spigpio_txrx_mode3(struct spi_device *spi,
                                      unsigned nsecs, u32 word, u8 bits)
 {
-       return bitbang_txrx_be_cpha1(spi, nsecs, 1, word, bits);
+       return bitbang_txrx_be_cpha1(spi, nsecs, 1, 0, word, bits);
 }
 
 

diff --git a/drivers/spi/spi_sh_sci.c b/drivers/spi/spi_sh_sci.c
index a511be7961a0a843f0d46c0b37dfb0c3dfd06175..5c6439161199a8cf604bd3b6bf08cd713d7ea912 100644 (file)
--- a/drivers/spi/spi_sh_sci.c
+++ b/drivers/spi/spi_sh_sci.c
@@ -83,25 +83,25 @@ static inline u32 getmiso(struct spi_device *dev)
 static u32 sh_sci_spi_txrx_mode0(struct spi_device *spi,
                                      unsigned nsecs, u32 word, u8 bits)
 {
-       return bitbang_txrx_be_cpha0(spi, nsecs, 0, word, bits);
+       return bitbang_txrx_be_cpha0(spi, nsecs, 0, 0, word, bits);
 }
 
 static u32 sh_sci_spi_txrx_mode1(struct spi_device *spi,
                                      unsigned nsecs, u32 word, u8 bits)
 {
-       return bitbang_txrx_be_cpha1(spi, nsecs, 0, word, bits);
+       return bitbang_txrx_be_cpha1(spi, nsecs, 0, 0, word, bits);
 }
 
 static u32 sh_sci_spi_txrx_mode2(struct spi_device *spi,
                                      unsigned nsecs, u32 word, u8 bits)
 {
-       return bitbang_txrx_be_cpha0(spi, nsecs, 1, word, bits);
+       return bitbang_txrx_be_cpha0(spi, nsecs, 1, 0, word, bits);
 }
 
 static u32 sh_sci_spi_txrx_mode3(struct spi_device *spi,
                                      unsigned nsecs, u32 word, u8 bits)
 {
-       return bitbang_txrx_be_cpha1(spi, nsecs, 1, word, bits);
+       return bitbang_txrx_be_cpha1(spi, nsecs, 1, 0, word, bits);
 }
 
 static void sh_sci_spi_chipselect(struct spi_device *dev, int value)