[PATCH rtems] i2c: Add non blocking read / write
Christian MAUDERER
christian.mauderer at embedded-brains.de
Mon Jun 21 14:07:53 UTC 2021
Ping.
Am 26.05.21 um 16:39 schrieb Christian Mauderer:
> 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.
> ---
> NOTE: This patch needs
> https://lists.rtems.org/pipermail/devel/2021-May/067462.html applied too.
>
> 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 <stdlib.h>
> #include <string.h>
>
> +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
>
>
--
--------------------------------------------
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