Re: [libgpiod] [PATCH 11/19] API: add support for SET_CONFIG

[Bartosz Golaszewski <bgolaszewski@baylibre.com>]

pt., 15 lis 2019 o 15:45 Kent Gibson <warthog618@gmail.com> napisał(a):
>
> Extend the libgpiod API to support the setting line configuration using the
> GPIO GPIOHANDLE_SET_CONFIG_IOCTL uAPI ioctl.
>
> The core change is the addition of gpiod_line_set_config, which provides a
> low level wrapper around the ioctl.
>
> Additionally, higher level helper functions, gpiod_line_set_flags,
> gpiod_line_set_direction_input, and gpiod_line_set_direction_output provide
> slightly simplified APIs for common use cases.
>
> Bulk forms of all functions are also provided.
>
> Signed-off-by: Kent Gibson <warthog618@gmail.com>
> ---
>  include/gpiod.h | 115 ++++++++++++++++++++++++++++
>  lib/core.c      | 196 +++++++++++++++++++++++++++++++++++++++++++++---
>  2 files changed, 300 insertions(+), 11 deletions(-)
>
> diff --git a/include/gpiod.h b/include/gpiod.h
> index 159d745..4053fd2 100644
> --- a/include/gpiod.h
> +++ b/include/gpiod.h
> @@ -1252,6 +1252,14 @@ void gpiod_line_release_bulk(struct gpiod_line_bulk *bulk) GPIOD_API;
>   */
>  bool gpiod_line_is_requested(struct gpiod_line *line) GPIOD_API;
>
> +/**
> + * @brief Check if the calling user has ownership of this line for values,
> + * not events.
> + * @param line GPIO line object.
> + * @return True if given line was requested, false otherwise.

I'd clarify: "requested for reading/setting values".

> + */
> +bool gpiod_line_is_requested_values(struct gpiod_line *line) GPIOD_API;
> +
>  /**
>   * @brief Check if the calling user has neither requested ownership of this
>   *        line nor configured any event notifications.
> @@ -1311,6 +1319,113 @@ int gpiod_line_set_value(struct gpiod_line *line, int value) GPIOD_API;
>  int gpiod_line_set_value_bulk(struct gpiod_line_bulk *bulk,
>                               const int *values) GPIOD_API;
>
> +/**
> + * @}
> + *
> + * @defgroup __line_config__ Setting line configuration
> + * @{
> + */
> +
> +/**
> + * @brief Update the configuration of a single GPIO line.
> + * @param line GPIO line object.
> + * @param direction Updated direction which may be one of
> + * GPIOD_LINE_REQUEST_DIRECTION_AS_IS, GPIOD_LINE_REQUEST_DIRECTION_INPUT,
> + * or GPIOD_LINE_REQUEST_DIRECTION_OUTPUT.
> + * @param flags Replacement flags.
> + * @param value The new output value for the line when direction is
> + * GPIOD_LINE_REQUEST_DIRECTION_OUTPUT.
> + * @return 0 is the operation succeeds. In case of an error this routine
> + *         returns -1 and sets the last error number.
> + */
> +int gpiod_line_set_config(struct gpiod_line *line, int direction,
> +                         int flags, int value) GPIOD_API;
> +
> +/**
> + * @brief Update the configuration of a set of GPIO lines.
> + * @param bulk Set of GPIO lines.
> + * @param direction Updated direction which may be one of
> + * GPIOD_LINE_REQUEST_DIRECTION_AS_IS, GPIOD_LINE_REQUEST_DIRECTION_INPUT,
> + * or GPIOD_LINE_REQUEST_DIRECTION_OUTPUT.
> + * @param flags Replacement flags.
> + * @param values An array holding line_bulk->num_lines new logical values
> + * for lines when direction is GPIOD_LINE_REQUEST_DIRECTION_OUTPUT.
> + * @return 0 is the operation succeeds. In case of an error this routine
> + *         returns -1 and sets the last error number.
> + *
> + * If the lines were not previously requested together, the behavior is
> + * undefined.
> + */
> +int gpiod_line_set_config_bulk(struct gpiod_line_bulk *bulk,
> +                              int direction, int flags,
> +                              const int *values) GPIOD_API;
> +
> +
> +/**
> + * @brief Update the configuration flags of a single GPIO line.
> + * @param line GPIO line object.
> + * @param flags Replacement flags.
> + * @return 0 is the operation succeeds. In case of an error this routine
> + *         returns -1 and sets the last error number.
> + */
> +int gpiod_line_set_flags(struct gpiod_line *line, int flags) GPIOD_API;
> +
> +/**
> + * @brief Update the configuration flags of a set of GPIO lines.
> + * @param bulk Set of GPIO lines.
> + * @param flags Replacement flags.
> + * @return 0 is the operation succeeds. In case of an error this routine
> + *         returns -1 and sets the last error number.
> + *
> + * If the lines were not previously requested together, the behavior is
> + * undefined.
> + */
> +int gpiod_line_set_flags_bulk(struct gpiod_line_bulk *bulk,
> +                             int flags) GPIOD_API;
> +
> +/**
> + * @brief Set the direction of a single GPIO line to input.
> + * @param line GPIO line object.
> + * @return 0 is the operation succeeds. In case of an error this routine
> + *         returns -1 and sets the last error number.
> + */
> +int gpiod_line_set_direction_input(struct gpiod_line *line) GPIOD_API;
> +
> +/**
> + * @brief Set the direction of a set of GPIO lines to input.
> + * @param bulk Set of GPIO lines.
> + * @return 0 is the operation succeeds. In case of an error this routine
> + *         returns -1 and sets the last error number.
> + *
> + * If the lines were not previously requested together, the behavior is
> + * undefined.
> + */
> +int gpiod_line_set_direction_bulk_input(struct gpiod_line_bulk *bulk
> +                                       ) GPIOD_API;

Please stick to the current convention of having "_bulk" at the end of
the function name.

> +
> +/**
> + * @brief Set the direction of a single GPIO line to output.
> + * @param line GPIO line object.
> + * @param value The logical value output on the line.
> + * @return 0 is the operation succeeds. In case of an error this routine
> + *         returns -1 and sets the last error number.
> + */
> +int gpiod_line_set_direction_output(struct gpiod_line *line,
> +                                   int value) GPIOD_API;
> +
> +/**
> + * @brief Set the direction of a set of GPIO lines to output.
> + * @param bulk Set of GPIO lines.
> + * @values The logical value to output for each line.
> + * @return 0 is the operation succeeds. In case of an error this routine
> + *         returns -1 and sets the last error number.
> + *
> + * If the lines were not previously requested together, the behavior is
> + * undefined.
> + */
> +int gpiod_line_set_direction_bulk_output(struct gpiod_line_bulk *bulk,
> +                                        const int *values) GPIOD_API;
> +
>  /**
>   * @}
>   *
> diff --git a/lib/core.c b/lib/core.c
> index 9b7d88f..c42cda5 100644
> --- a/lib/core.c
> +++ b/lib/core.c
> @@ -36,10 +36,13 @@ struct gpiod_line {
>         unsigned int offset;
>         int direction;
>         int active_state;
> -       __u32 flags;
> +       int output_value;
> +       __u32 lflags;
> +       __u32 cflags;

Ugh, these aren't very fortunate names - at first glance I have no
idea what they mean. Either document those or change the names to
something more obvious.

>
>         int state;
>         bool needs_update;
> +       bool as_is;
>
>         struct gpiod_chip *chip;
>         struct line_fd_handle *fd_handle;
> @@ -359,11 +362,11 @@ int gpiod_line_active_state(struct gpiod_line *line)
>
>  int gpiod_line_bias(struct gpiod_line *line)
>  {
> -       if (line->flags & GPIOLINE_FLAG_BIAS_DISABLE)
> +       if (line->lflags & GPIOLINE_FLAG_BIAS_DISABLE)
>                 return GPIOD_LINE_BIAS_DISABLE;
> -       if (line->flags & GPIOLINE_FLAG_BIAS_PULL_UP)
> +       if (line->lflags & GPIOLINE_FLAG_BIAS_PULL_UP)
>                 return GPIOD_LINE_BIAS_PULL_UP;
> -       if (line->flags & GPIOLINE_FLAG_BIAS_PULL_DOWN)
> +       if (line->lflags & GPIOLINE_FLAG_BIAS_PULL_DOWN)
>                 return GPIOD_LINE_BIAS_PULL_DOWN;
>
>         return GPIOD_LINE_BIAS_AS_IS;
> @@ -371,17 +374,17 @@ int gpiod_line_bias(struct gpiod_line *line)
>
>  bool gpiod_line_is_used(struct gpiod_line *line)
>  {
> -       return line->flags & GPIOLINE_FLAG_KERNEL;
> +       return line->lflags & GPIOLINE_FLAG_KERNEL;
>  }
>
>  bool gpiod_line_is_open_drain(struct gpiod_line *line)
>  {
> -       return line->flags & GPIOLINE_FLAG_OPEN_DRAIN;
> +       return line->lflags & GPIOLINE_FLAG_OPEN_DRAIN;
>  }
>
>  bool gpiod_line_is_open_source(struct gpiod_line *line)
>  {
> -       return line->flags & GPIOLINE_FLAG_OPEN_SOURCE;
> +       return line->lflags & GPIOLINE_FLAG_OPEN_SOURCE;
>  }
>
>  bool gpiod_line_needs_update(struct gpiod_line *line)
> @@ -408,7 +411,7 @@ int gpiod_line_update(struct gpiod_line *line)
>                                                 ? GPIOD_LINE_ACTIVE_STATE_LOW
>                                                 : GPIOD_LINE_ACTIVE_STATE_HIGH;
>
> -       line->flags = info.flags;
> +       line->lflags = info.flags;
>
>         strncpy(line->name, info.name, sizeof(line->name));
>         strncpy(line->consumer, info.consumer, sizeof(line->consumer));
> @@ -457,6 +460,20 @@ static bool line_bulk_all_requested(struct gpiod_line_bulk *bulk)
>         return true;
>  }
>
> +static bool line_bulk_all_requested_values(struct gpiod_line_bulk *bulk)
> +{
> +       struct gpiod_line *line, **lineptr;
> +
> +       gpiod_line_bulk_foreach_line(bulk, line, lineptr) {
> +               if (!gpiod_line_is_requested_values(line)) {
> +                       errno = EPERM;
> +                       return false;
> +               }
> +       }
> +
> +       return true;
> +}
> +
>  static bool line_bulk_all_free(struct gpiod_line_bulk *bulk)
>  {
>         struct gpiod_line *line, **lineptr;
> @@ -471,6 +488,27 @@ static bool line_bulk_all_free(struct gpiod_line_bulk *bulk)
>         return true;
>  }
>
> +static bool line_request_direction_is_valid(int direction)
> +{
> +       if ((direction == GPIOD_LINE_REQUEST_DIRECTION_AS_IS) ||
> +           (direction == GPIOD_LINE_REQUEST_DIRECTION_INPUT) ||
> +           (direction == GPIOD_LINE_REQUEST_DIRECTION_OUTPUT))
> +               return true;
> +
> +       errno = EINVAL;
> +       return false;
> +}
> +
> +static __u32 line_request_direction_to_gpio_handleflag(int direction)
> +{
> +       if (direction == GPIOD_LINE_REQUEST_DIRECTION_INPUT)
> +               return GPIOHANDLE_REQUEST_INPUT;
> +       if (direction == GPIOD_LINE_REQUEST_DIRECTION_OUTPUT)
> +               return GPIOHANDLE_REQUEST_OUTPUT;
> +
> +       return 0;
> +}
> +
>  static __u32 line_request_flag_to_gpio_handleflag(int flags)
>  {
>         int hflags = 0;
> @@ -495,7 +533,7 @@ static int line_request_values(struct gpiod_line_bulk *bulk,
>                                const struct gpiod_line_request_config *config,
>                                const int *default_vals)
>  {
> -       struct gpiod_line *line, **lineptr;
> +       struct gpiod_line *line;
>         struct line_fd_handle *line_fd;
>         struct gpiohandle_request req;
>         unsigned int i;
> @@ -524,7 +562,6 @@ static int line_request_values(struct gpiod_line_bulk *bulk,
>         else if (config->request_type == GPIOD_LINE_REQUEST_DIRECTION_OUTPUT)
>                 req.flags |= GPIOHANDLE_REQUEST_OUTPUT;
>
> -
>         gpiod_line_bulk_foreach_line_off(bulk, line, i) {
>                 req.lineoffsets[i] = gpiod_line_offset(line);
>                 if (config->request_type ==
> @@ -548,8 +585,14 @@ static int line_request_values(struct gpiod_line_bulk *bulk,
>         if (!line_fd)
>                 return -1;
>
> -       gpiod_line_bulk_foreach_line(bulk, line, lineptr) {
> +       gpiod_line_bulk_foreach_line_off(bulk, line, i) {
>                 line->state = LINE_REQUESTED_VALUES;
> +               line->cflags = config->flags;
> +               if (config->request_type ==
> +                       GPIOD_LINE_REQUEST_DIRECTION_OUTPUT)
> +                       line->output_value = req.default_values[i];
> +               if (config->request_type == GPIOD_LINE_REQUEST_DIRECTION_AS_IS)
> +                       line->as_is = true;
>                 line_set_fd(line, line_fd);
>                 line_maybe_update(line);
>         }
> @@ -590,6 +633,7 @@ static int line_request_event_single(struct gpiod_line *line,
>                 return -1;
>
>         line->state = LINE_REQUESTED_EVENTS;
> +       line->cflags = config->flags;
>         line_set_fd(line, line_fd);
>         line_maybe_update(line);
>
> @@ -688,6 +732,11 @@ bool gpiod_line_is_requested(struct gpiod_line *line)
>                 line->state == LINE_REQUESTED_EVENTS);
>  }
>
> +bool gpiod_line_is_requested_values(struct gpiod_line *line)
> +{
> +       return (line->state == LINE_REQUESTED_VALUES);
> +}
> +
>  bool gpiod_line_is_free(struct gpiod_line *line)
>  {
>         return line->state == LINE_FREE;
> @@ -766,9 +815,134 @@ int gpiod_line_set_value_bulk(struct gpiod_line_bulk *bulk, const int *values)
>         if (rv < 0)
>                 return -1;
>
> +       gpiod_line_bulk_foreach_line_off(bulk, line, i)
> +               line->output_value = data.values[i];
> +
> +       return 0;
> +}
> +
> +int gpiod_line_set_config(struct gpiod_line *line, int direction,
> +                         int flags, int value)
> +{
> +       struct gpiod_line_bulk bulk;
> +
> +       gpiod_line_bulk_init(&bulk);
> +       gpiod_line_bulk_add(&bulk, line);
> +
> +       return gpiod_line_set_config_bulk(&bulk, direction, flags, &value);
> +}
> +
> +int gpiod_line_set_config_bulk(struct gpiod_line_bulk *bulk,
> +                              int direction, int flags,
> +                              const int *values)
> +{
> +       struct gpiohandle_config hcfg;
> +       struct gpiod_line *line;
> +       unsigned int i;
> +       int rv, fd;
> +       bool as_is;
> +
> +       if (!line_bulk_same_chip(bulk) ||
> +           !line_bulk_all_requested_values(bulk))
> +               return -1;
> +
> +       if (!line_request_direction_is_valid(direction))
> +               return -1;
> +
> +       memset(&hcfg, 0, sizeof(hcfg));
> +
> +       hcfg.flags = line_request_flag_to_gpio_handleflag(flags);
> +       hcfg.flags |= line_request_direction_to_gpio_handleflag(direction);
> +       if (direction == GPIOD_LINE_REQUEST_DIRECTION_OUTPUT && values) {
> +               for (i = 0; i < gpiod_line_bulk_num_lines(bulk); i++)
> +                       hcfg.default_values[i] = (uint8_t)!!values[i];
> +       }
> +
> +       line = gpiod_line_bulk_get_line(bulk, 0);
> +       fd = line_get_fd(line);
> +
> +       rv = ioctl(fd, GPIOHANDLE_SET_CONFIG_IOCTL, &hcfg);
> +       if (rv < 0)
> +               return -1;
> +
> +       as_is = line->as_is && direction == GPIOD_LINE_REQUEST_DIRECTION_AS_IS;
> +       gpiod_line_bulk_foreach_line_off(bulk, line, i) {
> +               line->cflags = flags;
> +               if (direction == GPIOD_LINE_REQUEST_DIRECTION_OUTPUT)
> +                       line->output_value = hcfg.default_values[i];
> +               line->as_is = as_is;
> +               line_maybe_update(line);
> +       }
>         return 0;
>  }
>
> +int gpiod_line_set_flags(struct gpiod_line *line, int flags)
> +{
> +       struct gpiod_line_bulk bulk;
> +
> +       gpiod_line_bulk_init(&bulk);
> +       gpiod_line_bulk_add(&bulk, line);
> +
> +       return gpiod_line_set_flags_bulk(&bulk, flags);
> +}
> +
> +int gpiod_line_set_flags_bulk(struct gpiod_line_bulk *bulk, int flags)
> +{
> +       struct gpiod_line *line;
> +       int values[GPIOD_LINE_BULK_MAX_LINES];
> +       unsigned int i;
> +       int direction;
> +
> +       line = gpiod_line_bulk_get_line(bulk, 0);
> +       if (line->as_is) {

Can you explain the purpose of this as_is field? I'm not sure this is
really needed.

Bart


> +               errno = EPERM;
> +               return -1;
> +       }
> +       if (line->direction == GPIOD_LINE_DIRECTION_OUTPUT) {
> +               gpiod_line_bulk_foreach_line_off(bulk, line, i) {
> +                       values[i] = line->output_value;
> +               }
> +               direction = GPIOD_LINE_REQUEST_DIRECTION_OUTPUT;
> +       } else
> +               direction = GPIOD_LINE_REQUEST_DIRECTION_INPUT;
> +
> +       return gpiod_line_set_config_bulk(bulk, direction,
> +                                         flags, values);
> +}
> +
> +int gpiod_line_set_direction_input(struct gpiod_line *line)
> +{
> +       return gpiod_line_set_config(line, GPIOD_LINE_REQUEST_DIRECTION_INPUT,
> +                                    line->cflags, 0);
> +}
> +
> +int gpiod_line_set_direction_bulk_input(struct gpiod_line_bulk *bulk)
> +{
> +       struct gpiod_line *line;
> +
> +       line = gpiod_line_bulk_get_line(bulk, 0);
> +       return gpiod_line_set_config_bulk(bulk,
> +                                         GPIOD_LINE_REQUEST_DIRECTION_INPUT,
> +                                         line->cflags, NULL);
> +}
> +
> +int gpiod_line_set_direction_output(struct gpiod_line *line, int value)
> +{
> +       return gpiod_line_set_config(line, GPIOD_LINE_REQUEST_DIRECTION_OUTPUT,
> +                                    line->cflags, value);
> +}
> +
> +int gpiod_line_set_direction_bulk_output(struct gpiod_line_bulk *bulk,
> +                                       const int *values)
> +{
> +       struct gpiod_line *line;
> +
> +       line = gpiod_line_bulk_get_line(bulk, 0);
> +       return gpiod_line_set_config_bulk(bulk,
> +                                         GPIOD_LINE_REQUEST_DIRECTION_OUTPUT,
> +                                         line->cflags, values);
> +}
> +
>  int gpiod_line_event_wait(struct gpiod_line *line,
>                           const struct timespec *timeout)
>  {
> --
> 2.24.0
>