From 5bb5e013563ed6825aa5ca0c93e1b01db7e721cd Mon Sep 17 00:00:00 2001 From: Christian Mauderer Date: Wed, 26 May 2021 16:33:40 +0200 Subject: i2c: Add non blocking read / write This adds the possibility to open an I2C bus with O_NONBLOCK (or set it later via fcntl) to get non-blocking transmissions. This means that if the bus is busy, a read, write or transfer ioctl will return with a EAGAIN errno. --- cpukit/dev/i2c/i2c-bus.c | 45 +++++++++++++-- cpukit/include/dev/i2c/i2c.h | 44 +++++++++++++- testsuites/libtests/i2c01/init.c | 121 ++++++++++++++++++++++++++++++++++++++- 3 files changed, 203 insertions(+), 7 deletions(-) diff --git a/cpukit/dev/i2c/i2c-bus.c b/cpukit/dev/i2c/i2c-bus.c index 472222c4ab..618a817b1a 100644 --- a/cpukit/dev/i2c/i2c-bus.c +++ b/cpukit/dev/i2c/i2c-bus.c @@ -31,6 +31,11 @@ #include #include +int i2c_bus_try_obtain(i2c_bus *bus) +{ + return rtems_recursive_mutex_try_lock(&bus->mutex); +} + void i2c_bus_obtain(i2c_bus *bus) { rtems_recursive_mutex_lock(&bus->mutex); @@ -41,7 +46,12 @@ void i2c_bus_release(i2c_bus *bus) rtems_recursive_mutex_unlock(&bus->mutex); } -int i2c_bus_transfer(i2c_bus *bus, i2c_msg *msgs, uint32_t msg_count) +int i2c_bus_do_transfer( + i2c_bus *bus, + i2c_msg *msgs, + uint32_t msg_count, + uint32_t flags +) { int err; uint32_t i; @@ -63,13 +73,24 @@ int i2c_bus_transfer(i2c_bus *bus, i2c_msg *msgs, uint32_t msg_count) } } - i2c_bus_obtain(bus); + if ((flags & I2C_BUS_NOBLOCK) != 0) { + if (i2c_bus_try_obtain(bus) != 0) { + return -EAGAIN; + } + } else { + i2c_bus_obtain(bus); + } err = (*bus->transfer)(bus, msgs, msg_count); i2c_bus_release(bus); return err; } +int i2c_bus_transfer(i2c_bus *bus, i2c_msg *msgs, uint32_t msg_count) +{ + return i2c_bus_do_transfer(bus, msgs, msg_count, 0); +} + static ssize_t i2c_bus_read( rtems_libio_t *iop, void *buffer, @@ -84,12 +105,17 @@ static ssize_t i2c_bus_read( .buf = buffer }; int err; + unsigned flags = 0; if (bus->ten_bit_address) { msg.flags |= I2C_M_TEN; } - err = i2c_bus_transfer(bus, &msg, 1); + if (rtems_libio_iop_is_no_delay(iop)) { + flags |= I2C_BUS_NOBLOCK; + } + + err = i2c_bus_do_transfer(bus, &msg, 1, flags); if (err == 0) { return msg.len; } else { @@ -111,12 +137,17 @@ static ssize_t i2c_bus_write( .buf = RTEMS_DECONST(void *, buffer) }; int err; + unsigned flags = 0; if (bus->ten_bit_address) { msg.flags |= I2C_M_TEN; } - err = i2c_bus_transfer(bus, &msg, 1); + if (rtems_libio_iop_is_no_delay(iop)) { + flags |= I2C_BUS_NOBLOCK; + } + + err = i2c_bus_do_transfer(bus, &msg, 1, flags); if (err == 0) { return msg.len; } else { @@ -133,12 +164,16 @@ static int i2c_bus_ioctl( i2c_bus *bus = IMFS_generic_get_context_by_iop(iop); i2c_rdwr_ioctl_data *rdwr; int err; + unsigned flags = 0; switch (command) { case I2C_RDWR: rdwr = arg; if (rdwr->nmsgs > 0) { - err = i2c_bus_transfer(bus, rdwr->msgs, rdwr->nmsgs); + if (rtems_libio_iop_is_no_delay(iop)) { + flags |= I2C_BUS_NOBLOCK; + } + err = i2c_bus_do_transfer(bus, rdwr->msgs, rdwr->nmsgs, flags); } else { err = 0; } diff --git a/cpukit/include/dev/i2c/i2c.h b/cpukit/include/dev/i2c/i2c.h index ac2c369785..5aa45e390c 100644 --- a/cpukit/include/dev/i2c/i2c.h +++ b/cpukit/include/dev/i2c/i2c.h @@ -242,6 +242,16 @@ int i2c_bus_register( const char *bus_path ); +/** + * @brief Try to obtain the bus. + * + * @param[in] bus The bus control. + * + * @retval 0 Successful operation. + * @retval EBUSY if mutex is already locked. + */ +int i2c_bus_try_obtain(i2c_bus *bus); + /** * @brief Obtains the bus. * @@ -259,7 +269,8 @@ void i2c_bus_release(i2c_bus *bus); /** * @brief Transfers I2C messages. * - * The bus is obtained before the transfer and released afterwards. + * The bus is obtained before the transfer and released afterwards. This is the + * same like calling @ref i2c_bus_do_transfer with flags set to 0. * * @param[in] bus The bus control. * @param[in] msgs The messages to transfer. @@ -271,6 +282,37 @@ void i2c_bus_release(i2c_bus *bus); */ int i2c_bus_transfer(i2c_bus *bus, i2c_msg *msgs, uint32_t msg_count); +/** + * @brief Transfers I2C messages with optional flags. + * + * The bus is obtained before the transfer and released afterwards. If the flag + * I2C_BUS_NOBLOCK is set and the bus is already obtained, nothing will be + * transfered and the function returns with an -EAGAIN. + * + * @param[in] bus The bus control. + * @param[in] msgs The messages to transfer. + * @param[in] msg_count The count of messages to transfer. It must be + * positive. + * @param[in] flags Options for the whole transfer. + * + * @retval 0 Successful operation. + * @retval -EAGAIN if @ref I2C_BUS_NOBLOCK is set and the bus is already + * obtained. + * @retval negative Negative error number in case of an error. + */ +int i2c_bus_do_transfer( + i2c_bus *bus, + i2c_msg *msgs, + uint32_t msg_count, + uint32_t flags +); + +/** + * @brief I2C bus transfer flag to indicate that the task should not block if + * the bus is busy on a new transfer. + */ +#define I2C_BUS_NOBLOCK (1u << 0) + /** @} */ /** diff --git a/testsuites/libtests/i2c01/init.c b/testsuites/libtests/i2c01/init.c index 83027ed548..c71b78c275 100644 --- a/testsuites/libtests/i2c01/init.c +++ b/testsuites/libtests/i2c01/init.c @@ -336,6 +336,124 @@ static void test_simple_read_write(test_bus *bus, int fd) rtems_test_assert(memcmp(&buf[0], &abc[0], sizeof(buf)) == 0); } +typedef struct { + rtems_id caller; + int fd; +} bus_obtainer_ctx; + +static void bus_obtainer_task(rtems_task_argument arg) +{ + rtems_event_set e = 0; + bus_obtainer_ctx *c = (bus_obtainer_ctx *) arg; + int rv; + rtems_status_code sc; + + rv = ioctl(c->fd, I2C_BUS_OBTAIN); + rtems_test_assert(rv == 0); + + sc = rtems_event_send(c->caller, RTEMS_EVENT_1); + rtems_test_assert(sc == RTEMS_SUCCESSFUL); + sc = rtems_event_receive( + RTEMS_EVENT_1, + RTEMS_EVENT_ANY | RTEMS_WAIT, + 100, + &e + ); + rtems_test_assert(sc == RTEMS_SUCCESSFUL); + + rv = ioctl(c->fd, I2C_BUS_RELEASE); + rtems_test_assert(rv == 0); + + sc = rtems_event_send(c->caller, RTEMS_EVENT_1); + rtems_test_assert(sc == RTEMS_SUCCESSFUL); +} + +static void test_nonblock_read_write(test_bus *bus, int fd) +{ + int flags; + int rv; + char buf[3]; + ssize_t n; + i2c_msg msgs[] = {{ + .addr = 1, + .flags = I2C_M_STOP, + .len = sizeof(buf), + .buf = (uint8_t *) buf, + }}; + struct i2c_rdwr_ioctl_data payload = { + .msgs = msgs, + .nmsgs = sizeof(msgs)/sizeof(msgs[0]), + }; + rtems_id id; + rtems_event_set e = 0; + bus_obtainer_ctx ctx = { + .caller = rtems_task_self(), + .fd = fd, + }; + rtems_status_code sc; + + flags = fcntl(fd, F_GETFL, 0); + rtems_test_assert(flags > 0); + + rv = fcntl(fd, F_SETFL, flags | O_NONBLOCK); + rtems_test_assert(rv != -1); + + sc = rtems_task_create( + rtems_build_name('O', 'B', 'T', 'A'), + 2, + RTEMS_MINIMUM_STACK_SIZE, + RTEMS_DEFAULT_MODES, + RTEMS_DEFAULT_ATTRIBUTES, + &id + ); + rtems_test_assert(sc == RTEMS_SUCCESSFUL); + + sc = rtems_task_start( + id, + bus_obtainer_task, + (rtems_task_argument) &ctx + ); + rtems_test_assert(sc == RTEMS_SUCCESSFUL); + + sc = rtems_event_receive( + RTEMS_EVENT_1, + RTEMS_EVENT_ANY | RTEMS_WAIT, + 100, + &e + ); + rtems_test_assert(sc == RTEMS_SUCCESSFUL); + + errno = 0; + n = read(fd, &buf[0], sizeof(buf)); + rtems_test_assert(n == -1); + rtems_test_assert(errno == EAGAIN); + + errno = 0; + n = write(fd, &buf[0], sizeof(buf)); + rtems_test_assert(n == -1); + rtems_test_assert(errno == EAGAIN); + + errno = 0; + rv = ioctl(fd, I2C_RDWR, &payload); + rtems_test_assert(rv == -1); + rtems_test_assert(errno == EAGAIN); + + sc = rtems_event_send(id, RTEMS_EVENT_1); + rtems_test_assert(sc == RTEMS_SUCCESSFUL); + sc = rtems_event_receive( + RTEMS_EVENT_1, + RTEMS_EVENT_ANY | RTEMS_WAIT, + 100, + &e + ); + rtems_test_assert(sc == RTEMS_SUCCESSFUL); + sc = rtems_task_delete(id); + rtems_test_assert(sc == RTEMS_SUCCESSFUL); + + rv = fcntl(fd, F_SETFL, flags); + rtems_test_assert(rv != -1); +} + static void test_gpio_nxp_pca9535(void) { int rv; @@ -627,6 +745,7 @@ static void test(void) rtems_test_assert(bus->base.timeout == 0); test_simple_read_write(bus, fd); + test_nonblock_read_write(bus, fd); test_eeprom(bus); test_gpio_nxp_pca9535(); test_switch_nxp_pca9548a(); @@ -657,7 +776,7 @@ static void Init(rtems_task_argument arg) #define CONFIGURE_MAXIMUM_FILE_DESCRIPTORS 7 -#define CONFIGURE_MAXIMUM_TASKS 1 +#define CONFIGURE_MAXIMUM_TASKS 2 #define CONFIGURE_MAXIMUM_SEMAPHORES 1 -- cgit v1.2.3