[libgpiod,v3,07/14] core: add support for SET_CONFIG

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 | 123 +++++++++++++++++++++++++++++++
 lib/core.c      | 187 +++++++++++++++++++++++++++++++++++++++++++++++-
 2 files changed, 307 insertions(+), 3 deletions(-)

pon., 25 lis 2019 o 15:32 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 | 123 +++++++++++++++++++++++++++++++
>  lib/core.c      | 187 +++++++++++++++++++++++++++++++++++++++++++++++-
>  2 files changed, 307 insertions(+), 3 deletions(-)
>
> diff --git a/include/gpiod.h b/include/gpiod.h
> index 86c3ea9..185e2f4 100644
> --- a/include/gpiod.h
> +++ b/include/gpiod.h
> @@ -1246,6 +1246,15 @@ 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.

For consistency: please align this with the beginning of the
description above...

> + * @param line GPIO line object.
> + * @return True if given line was requested for reading/setting values,
> + *         false otherwise.
> + */
> +bool gpiod_line_is_requested_values(struct gpiod_line *line) GPIOD_API;

... but also: why do we need to export this anyway?

> +
>  /**
>   * @brief Check if the calling user has neither requested ownership of this
>   *        line nor configured any event notifications.
> @@ -1296,6 +1305,7 @@ int gpiod_line_set_value(struct gpiod_line *line, int value) GPIOD_API;
>   * @brief Set the values of a set of GPIO lines.
>   * @param bulk Set of GPIO lines to reserve.
>   * @param values An array holding line_bulk->num_lines new values for lines.
> + *               A NULL pointer is interpreted as a logical low for all lines.

This looks like part of a different commit.

>   * @return 0 is the operation succeeds. In case of an error this routine
>   *         returns -1 and sets the last error number.
>   *
> @@ -1305,6 +1315,119 @@ 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.
> + *               A NULL pointer is interpreted as a logical low for all 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_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_input_bulk(struct gpiod_line_bulk *bulk
> +                                       ) GPIOD_API;
> +
> +/**
> + * @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.
> + * @param values An array holding line_bulk->num_lines new logical values
> + *               for lines.  A NULL pointer is interpreted as a logical low
> + *               for all 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_output_bulk(struct gpiod_line_bulk *bulk,
> +                                        const int *values) GPIOD_API;
> +
>  /**
>   * @}
>   *
> diff --git a/lib/core.c b/lib/core.c
> index 0465de9..71bb4fb 100644
> --- a/lib/core.c
> +++ b/lib/core.c
> @@ -34,10 +34,26 @@ struct line_fd_handle {
>
>  struct gpiod_line {
>         unsigned int offset;
> +
> +       /* The GPIOD_LINE_DIRECTION */
>         int direction;
> +
> +       /* The GPIOD_LINE_ACTIVE_STATE */
>         int active_state;
> +
> +       /* The logical value last written to the line. */
> +       int output_value;
> +
> +       /* The GPIOLINE_FLAGs returned by GPIO_GET_LINEINFO_IOCTL */
>         __u32 info_flags;
>
> +       /* The GPIOD_LINE_REQUEST_FLAGs provided to request the line. */
> +       __u32 req_flags;
> +
> +       /*
> +        * Indicator of LINE_FREE, LINE_REQUESTED_VALUES or
> +        *  LINE_REQUESTED_EVENTS
> +        */
>         int state;

Please include the mention on documenting this in the commit message.
Otherwise it looks like it should be part of a different commit.

>
>         struct gpiod_chip *chip;
> @@ -445,6 +461,20 @@ 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;
> @@ -459,6 +489,27 @@ 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;
> +}

Same here: please be a bit more elaborate in the commit message. Say
something like: "while at it: restructure the code by doing this and
that".

> +
> +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;
> @@ -483,7 +534,7 @@ 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;
> @@ -512,7 +563,6 @@ 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;
>
> -

Fixing stray newlines etc should be in separate commits too IMO but
let's let is slip here, this is already a big patch anyway.

>         gpiod_line_bulk_foreach_line_off(bulk, line, i) {
>                 req.lineoffsets[i] = gpiod_line_offset(line);
>                 if (config->request_type ==
> @@ -536,8 +586,12 @@ 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->req_flags = config->flags;
> +               if (config->request_type ==
> +                       GPIOD_LINE_REQUEST_DIRECTION_OUTPUT)

Add another tab here because otherwise there's no indentation
difference between this line and the line below.

> +                       line->output_value = req.default_values[i];
>                 line_set_fd(line, line_fd);
>
>                 rv = gpiod_line_update(line);
> @@ -583,6 +637,7 @@ static int line_request_event_single(struct gpiod_line *line,
>                 return -1;
>
>         line->state = LINE_REQUESTED_EVENTS;
> +       line->req_flags = config->flags;
>         line_set_fd(line, line_fd);
>
>         rv = gpiod_line_update(line);
> @@ -686,6 +741,11 @@ 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 +826,130 @@ 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;
> +
> +       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;
> +
> +       gpiod_line_bulk_foreach_line_off(bulk, line, i) {
> +               line->req_flags = flags;
> +               if (direction == GPIOD_LINE_REQUEST_DIRECTION_OUTPUT)
> +                       line->output_value = hcfg.default_values[i];

Please add a newline here.

> +               rv = gpiod_line_update(line);
> +               if (rv < 0)
> +                       return rv;
> +       }
> +       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->direction == GPIOD_LINE_DIRECTION_OUTPUT) {
> +               gpiod_line_bulk_foreach_line_off(bulk, line, i) {
> +                       values[i] = line->output_value;
> +               }

No need for brackets here.



> +               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->req_flags, 0);
> +}
> +
> +int gpiod_line_set_direction_input_bulk(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->req_flags, 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->req_flags, value);
> +}
> +
> +int gpiod_line_set_direction_output_bulk(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->req_flags, values);
> +}
> +
>  int gpiod_line_event_wait(struct gpiod_line *line,
>                           const struct timespec *timeout)
>  {
> --
> 2.24.0
>