diff options
Diffstat (limited to 'Documentation/spi')
| -rw-r--r-- | Documentation/spi/00-INDEX | 22 | ||||
| -rw-r--r-- | Documentation/spi/spi-summary | 25 | ||||
| -rw-r--r-- | Documentation/spi/spidev | 6 | ||||
| -rw-r--r-- | Documentation/spi/spidev_fdx.c | 8 | ||||
| -rw-r--r-- | Documentation/spi/spidev_test.c | 45 |
5 files changed, 91 insertions, 15 deletions
diff --git a/Documentation/spi/00-INDEX b/Documentation/spi/00-INDEX new file mode 100644 index 00000000000..a128fa83551 --- /dev/null +++ b/Documentation/spi/00-INDEX @@ -0,0 +1,22 @@ +00-INDEX + - this file. +Makefile + - Makefile for the example sourcefiles. +butterfly + - AVR Butterfly SPI driver overview and pin configuration. +ep93xx_spi + - Basic EP93xx SPI driver configuration. +pxa2xx + - PXA2xx SPI master controller build by spi_message fifo wq +spidev + - Intro to the userspace API for spi devices +spidev_fdx.c + - spidev example file +spi-lm70llp + - Connecting an LM70-LLP sensor to the kernel via the SPI subsys. +spi-sc18is602 + - NXP SC18IS602/603 I2C-bus to SPI bridge +spi-summary + - (Linux) SPI overview. If unsure about SPI or SPI in Linux, start here. +spidev_test.c + - SPI testing utility. diff --git a/Documentation/spi/spi-summary b/Documentation/spi/spi-summary index f21edb98341..7982bcc4d15 100644 --- a/Documentation/spi/spi-summary +++ b/Documentation/spi/spi-summary @@ -34,7 +34,7 @@ SPI slave functions are usually not interoperable between vendors - It may also be used to stream data in either direction (half duplex), or both of them at the same time (full duplex). - - Some devices may use eight bit words. Others may different word + - Some devices may use eight bit words. Others may use different word lengths, such as streams of 12-bit or 20-bit digital samples. - Words are usually sent with their most significant bit (MSB) first, @@ -121,7 +121,7 @@ active. So the master must set the clock to inactive before selecting a slave, and the slave can tell the chosen polarity by sampling the clock level when its select line goes active. That's why many devices support for example both modes 0 and 3: they don't care about polarity, -and alway clock data in/out on rising clock edges. +and always clock data in/out on rising clock edges. How do these driver programming interfaces work? @@ -139,7 +139,7 @@ a command and then reading its response. There are two types of SPI driver, here called: - Controller drivers ... controllers may be built in to System-On-Chip + Controller drivers ... controllers may be built into System-On-Chip processors, and often support both Master and Slave roles. These drivers touch hardware registers and may use DMA. Or they can be PIO bitbangers, needing just GPIO pins. @@ -543,12 +543,27 @@ SPI MASTER METHODS queuing transfers that arrive in the meantime. When the driver is finished with this message, it must call spi_finalize_current_message() so the subsystem can issue the next - transfer. This may sleep. + message. This may sleep. + + master->transfer_one(struct spi_master *master, struct spi_device *spi, + struct spi_transfer *transfer) + The subsystem calls the driver to transfer a single transfer while + queuing transfers that arrive in the meantime. When the driver is + finished with this transfer, it must call + spi_finalize_current_transfer() so the subsystem can issue the next + transfer. This may sleep. Note: transfer_one and transfer_one_message + are mutually exclusive; when both are set, the generic subsystem does + not call your transfer_one callback. + + Return values: + negative errno: error + 0: transfer is finished + 1: transfer is still in progress DEPRECATED METHODS master->transfer(struct spi_device *spi, struct spi_message *message) - This must not sleep. Its responsibility is arrange that the + This must not sleep. Its responsibility is to arrange that the transfer happens and its complete() callback is issued. The two will normally happen later, after other transfers complete, and if the controller is idle it will need to be kickstarted. This diff --git a/Documentation/spi/spidev b/Documentation/spi/spidev index ed2da5e5b28..3d14035b176 100644 --- a/Documentation/spi/spidev +++ b/Documentation/spi/spidev @@ -85,6 +85,12 @@ settings for data transfer parameters: SPI_MODE_0..SPI_MODE_3; or if you prefer you can combine SPI_CPOL (clock polarity, idle high iff this is set) or SPI_CPHA (clock phase, sample on trailing edge iff this is set) flags. + Note that this request is limited to SPI mode flags that fit in a + single byte. + + SPI_IOC_RD_MODE32, SPI_IOC_WR_MODE32 ... pass a pointer to a uin32_t + which will return (RD) or assign (WR) the full SPI transfer mode, + not limited to the bits that fit in one byte. SPI_IOC_RD_LSB_FIRST, SPI_IOC_WR_LSB_FIRST ... pass a pointer to a byte which will return (RD) or assign (WR) the bit justification used to diff --git a/Documentation/spi/spidev_fdx.c b/Documentation/spi/spidev_fdx.c index 36ec0774ca0..0ea3e51292f 100644 --- a/Documentation/spi/spidev_fdx.c +++ b/Documentation/spi/spidev_fdx.c @@ -78,10 +78,10 @@ static void do_msg(int fd, int len) static void dumpstat(const char *name, int fd) { - __u8 mode, lsb, bits; - __u32 speed; + __u8 lsb, bits; + __u32 mode, speed; - if (ioctl(fd, SPI_IOC_RD_MODE, &mode) < 0) { + if (ioctl(fd, SPI_IOC_RD_MODE32, &mode) < 0) { perror("SPI rd_mode"); return; } @@ -98,7 +98,7 @@ static void dumpstat(const char *name, int fd) return; } - printf("%s: spi mode %d, %d bits %sper word, %d Hz max\n", + printf("%s: spi mode 0x%x, %d bits %sper word, %d Hz max\n", name, mode, bits, lsb ? "(lsb first) " : "", speed); } diff --git a/Documentation/spi/spidev_test.c b/Documentation/spi/spidev_test.c index 16feda90146..3a2f9d59eda 100644 --- a/Documentation/spi/spidev_test.c +++ b/Documentation/spi/spidev_test.c @@ -30,7 +30,7 @@ static void pabort(const char *s) } static const char *device = "/dev/spidev1.1"; -static uint8_t mode; +static uint32_t mode; static uint8_t bits = 8; static uint32_t speed = 500000; static uint16_t delay; @@ -57,6 +57,21 @@ static void transfer(int fd) .bits_per_word = bits, }; + if (mode & SPI_TX_QUAD) + tr.tx_nbits = 4; + else if (mode & SPI_TX_DUAL) + tr.tx_nbits = 2; + if (mode & SPI_RX_QUAD) + tr.rx_nbits = 4; + else if (mode & SPI_RX_DUAL) + tr.rx_nbits = 2; + if (!(mode & SPI_LOOP)) { + if (mode & (SPI_TX_QUAD | SPI_TX_DUAL)) + tr.rx_buf = 0; + else if (mode & (SPI_RX_QUAD | SPI_RX_DUAL)) + tr.tx_buf = 0; + } + ret = ioctl(fd, SPI_IOC_MESSAGE(1), &tr); if (ret < 1) pabort("can't send spi message"); @@ -81,7 +96,11 @@ static void print_usage(const char *prog) " -O --cpol clock polarity\n" " -L --lsb least significant bit first\n" " -C --cs-high chip select active high\n" - " -3 --3wire SI/SO signals shared\n"); + " -3 --3wire SI/SO signals shared\n" + " -N --no-cs no chip select\n" + " -R --ready slave pulls low to pause\n" + " -2 --dual dual transfer\n" + " -4 --quad quad transfer\n"); exit(1); } @@ -101,11 +120,13 @@ static void parse_opts(int argc, char *argv[]) { "3wire", 0, 0, '3' }, { "no-cs", 0, 0, 'N' }, { "ready", 0, 0, 'R' }, + { "dual", 0, 0, '2' }, + { "quad", 0, 0, '4' }, { NULL, 0, 0, 0 }, }; int c; - c = getopt_long(argc, argv, "D:s:d:b:lHOLC3NR", lopts, NULL); + c = getopt_long(argc, argv, "D:s:d:b:lHOLC3NR24", lopts, NULL); if (c == -1) break; @@ -147,11 +168,23 @@ static void parse_opts(int argc, char *argv[]) case 'R': mode |= SPI_READY; break; + case '2': + mode |= SPI_TX_DUAL; + break; + case '4': + mode |= SPI_TX_QUAD; + break; default: print_usage(argv[0]); break; } } + if (mode & SPI_LOOP) { + if (mode & SPI_TX_DUAL) + mode |= SPI_RX_DUAL; + if (mode & SPI_TX_QUAD) + mode |= SPI_RX_QUAD; + } } int main(int argc, char *argv[]) @@ -168,11 +201,11 @@ int main(int argc, char *argv[]) /* * spi mode */ - ret = ioctl(fd, SPI_IOC_WR_MODE, &mode); + ret = ioctl(fd, SPI_IOC_WR_MODE32, &mode); if (ret == -1) pabort("can't set spi mode"); - ret = ioctl(fd, SPI_IOC_RD_MODE, &mode); + ret = ioctl(fd, SPI_IOC_RD_MODE32, &mode); if (ret == -1) pabort("can't get spi mode"); @@ -198,7 +231,7 @@ int main(int argc, char *argv[]) if (ret == -1) pabort("can't get max speed hz"); - printf("spi mode: %d\n", mode); + printf("spi mode: 0x%x\n", mode); printf("bits per word: %d\n", bits); printf("max speed: %d Hz (%d KHz)\n", speed, speed/1000); |