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Merge request <a href="https://gitlab.rtems.org/rtems/rtos/rtems/-/merge_requests/1499">!1499</a> was reviewed by <a href="https://gitlab.rtems.org/c-mauderer">Christian Mauderer</a>
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<p style="color: #777777;">
<a href="https://gitlab.rtems.org/c-mauderer">Christian Mauderer</a>
commented on a
discussion on <a href="https://gitlab.rtems.org/rtems/rtos/rtems/-/merge_requests/1499#note_159813">cpukit/include/dev/gpio/gpio.h</a>:
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<td class="new_line diff-line-num new" data-linenumber="132" style="width: 35px; color: rgba(5,5,6,.24); border-right-width: 1px; border-right-color: #c7f0d2; border-right-style: solid; padding: inherit;" align="right" bgcolor="#ddfbe6">
132
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<td class="line_content new" style="padding: inherit;" bgcolor="#ecfdf0"><pre style="display: block; font-size: 14px; color: #3a383f; position: relative; font-family: "GitLab Mono", "JetBrains Mono", "Menlo", "DejaVu Sans Mono", "Liberation Mono", "Consolas", "Ubuntu Mono", "Courier New", "andale mono", "lucida console", monospace; font-variant-ligatures: none; word-break: break-all; word-wrap: break-word; background-color: inherit; border-radius: 2px; margin: 0; padding: 0; border: inherit solid #dcdcde;">+<span class="line" data-lang="c"><span class="cm" style="color: #999988; font-style: italic;"> */</span></span>
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<td class="new_line diff-line-num new" data-linenumber="133" style="width: 35px; color: rgba(5,5,6,.24); border-right-width: 1px; border-right-color: #c7f0d2; border-right-style: solid; padding: inherit;" align="right" bgcolor="#ddfbe6">
133
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<td class="line_content new" style="padding: inherit;" bgcolor="#ecfdf0"><pre style="display: block; font-size: 14px; color: #3a383f; position: relative; font-family: "GitLab Mono", "JetBrains Mono", "Menlo", "DejaVu Sans Mono", "Liberation Mono", "Consolas", "Ubuntu Mono", "Courier New", "andale mono", "lucida console", monospace; font-variant-ligatures: none; word-break: break-all; word-wrap: break-word; background-color: inherit; border-radius: 2px; margin: 0; padding: 0; border: inherit solid #dcdcde;">+<span class="line" data-lang="c"> <span class="n" style="color: #333333;">RTEMS_GPIO_DIRECTION_OUTPUT</span></span>
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<td class="new_line diff-line-num new" data-linenumber="134" style="width: 35px; color: rgba(5,5,6,.24); border-right-width: 1px; border-right-color: #c7f0d2; border-right-style: solid; padding: inherit;" align="right" bgcolor="#ddfbe6">
134
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<td class="line_content new" style="padding: inherit;" bgcolor="#ecfdf0"><pre style="display: block; font-size: 14px; color: #3a383f; position: relative; font-family: "GitLab Mono", "JetBrains Mono", "Menlo", "DejaVu Sans Mono", "Liberation Mono", "Consolas", "Ubuntu Mono", "Courier New", "andale mono", "lucida console", monospace; font-variant-ligatures: none; word-break: break-all; word-wrap: break-word; background-color: inherit; border-radius: 2px; margin: 0; padding: 0; border: inherit solid #dcdcde;">+<span class="line" data-lang="c"><span class="p">}</span> <span class="n" style="color: #333333;">rtems_gpio_direction</span><span class="p">;</span></span>
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<p dir="auto" style="color: #3a383f; margin: 0px;" align="initial">Two values would make it possible to distinguish between not yet initialized pins and pins explicitly set to low power mode. But I haven't found a sensible use case for that yet.</p>
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<p style="color: #777777;">
<a href="https://gitlab.rtems.org/c-mauderer">Christian Mauderer</a>
commented on a
discussion on <a href="https://gitlab.rtems.org/rtems/rtos/rtems/-/merge_requests/1499#note_159814">cpukit/include/dev/gpio/gpio.h</a>:
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<td class="new_line diff-line-num new" data-linenumber="1168" style="width: 35px; color: rgba(5,5,6,.24); border-right-width: 1px; border-right-color: #c7f0d2; border-right-style: solid; padding: inherit;" align="right" bgcolor="#ddfbe6">
1168
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<td class="line_content new" style="padding: inherit;" bgcolor="#ecfdf0"><pre style="display: block; font-size: 14px; color: #3a383f; position: relative; font-family: "GitLab Mono", "JetBrains Mono", "Menlo", "DejaVu Sans Mono", "Liberation Mono", "Consolas", "Ubuntu Mono", "Courier New", "andale mono", "lucida console", monospace; font-variant-ligatures: none; word-break: break-all; word-wrap: break-word; background-color: inherit; border-radius: 2px; margin: 0; padding: 0; border: inherit solid #dcdcde;">+<span class="line" data-lang="c"><span class="cm" style="color: #999988; font-style: italic;"> * @retval -1 An error occurred. The errno is set to indicate the error.</span></span>
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<td class="new_line diff-line-num new" data-linenumber="1169" style="width: 35px; color: rgba(5,5,6,.24); border-right-width: 1px; border-right-color: #c7f0d2; border-right-style: solid; padding: inherit;" align="right" bgcolor="#ddfbe6">
1169
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<td class="line_content new" style="padding: inherit;" bgcolor="#ecfdf0"><pre style="display: block; font-size: 14px; color: #3a383f; position: relative; font-family: "GitLab Mono", "JetBrains Mono", "Menlo", "DejaVu Sans Mono", "Liberation Mono", "Consolas", "Ubuntu Mono", "Courier New", "andale mono", "lucida console", monospace; font-variant-ligatures: none; word-break: break-all; word-wrap: break-word; background-color: inherit; border-radius: 2px; margin: 0; padding: 0; border: inherit solid #dcdcde;">+<span class="line" data-lang="c"><span class="cm" style="color: #999988; font-style: italic;"> */</span></span>
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<td class="new_line diff-line-num new" data-linenumber="1170" style="width: 35px; color: rgba(5,5,6,.24); border-right-width: 1px; border-right-color: #c7f0d2; border-right-style: solid; padding: inherit;" align="right" bgcolor="#ddfbe6">
1170
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<td class="line_content new" style="padding: inherit;" bgcolor="#ecfdf0"><pre style="display: block; font-size: 14px; color: #3a383f; position: relative; font-family: "GitLab Mono", "JetBrains Mono", "Menlo", "DejaVu Sans Mono", "Liberation Mono", "Consolas", "Ubuntu Mono", "Courier New", "andale mono", "lucida console", monospace; font-variant-ligatures: none; word-break: break-all; word-wrap: break-word; background-color: inherit; border-radius: 2px; margin: 0; padding: 0; border: inherit solid #dcdcde;">+<span class="line" data-lang="c"><span class="kt" style="color: #445588; font-weight: 600;">int</span> <span class="n" style="color: #333333;">rtems_gpio_pin_irq_enable</span><span class="p">(</span><span class="kt" style="color: #445588; font-weight: 600;">int</span> <span class="n" style="color: #333333;">fd</span><span class="p">,</span> <span class="kt" style="color: #445588; font-weight: 600;">uint32_t</span> <span class="n" style="color: #333333;">pin</span><span class="p">,</span></span>
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<p dir="auto" style="color: #3a383f; margin: 0px 0px 1rem;" align="initial">An interrupt API is quite useful for GPIO pins if you ask me. It makes it simpler to have drivers for peripherals which are either directly connected to a normal interrupt or to some GPIO construction. For slow GPIOs (connected via I2C or SPI), it would most likely be a call that is executed from within an interrupt server.</p>
<p dir="auto" style="color: #3a383f; margin: 0px 0px 1rem;" align="initial">It would be even simpler if the interrupts would use the default RTEMS interrupt API. That would be a model that is more similar to Linux or FreeBSD where most interrupt capable GPIO controllers are also interrupt controllers. For example the controller in the Beagle has a device tree binding for that:</p>
<p dir="auto" style="color: #3a383f; margin: 0px 0px 1rem;" align="initial"><a href="https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/Documentation/devicetree/bindings/gpio/ti,omap-gpio.yaml#n37" rel="nofollow noreferrer noopener" target="_blank" style="margin-top: 0px;">https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/Documentation/devicetree/bindings/gpio/ti,omap-gpio.yaml#n37</a></p>
<p dir="auto" style="color: #3a383f; margin: 0px;" align="initial">But I think it's a bit tricky to add additional interrupt controllers (maybe even dynamically) to our interrupt API. Therefore, I would just go for a similar but separate API in the GPIO drivers.</p>
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