[gpio] Add a framework for GPIO controllers

Signed-off-by: Michael Brown <mcb30@ipxe.org>

src/core/gpio.c

@@ -0,0 +1,165 @@
+/*
+ * Copyright (C) 2025 Michael Brown <mbrown@fensystems.co.uk>.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation; either version 2 of the
+ * License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
+ * 02110-1301, USA.
+ *
+ * You can also choose to distribute this program under the terms of
+ * the Unmodified Binary Distribution Licence (as given in the file
+ * COPYING.UBDL), provided that you have satisfied its requirements.
+ */
+
+FILE_LICENCE ( GPL2_OR_LATER_OR_UBDL );
+
+#include <stdlib.h>
+#include <errno.h>
+#include <ipxe/gpio.h>
+
+/** @file
+ *
+ * General purpose I/O
+ *
+ */
+
+/** List of GPIO controllers */
+static LIST_HEAD ( all_gpios );
+
+/**
+ * Allocate GPIO controller
+ *
+ * @v count		Number of GPIO pins
+ * @v priv_len		Size of driver-private data
+ * @ret gpios		GPIO controller, or NULL
+ */
+struct gpios * alloc_gpios ( unsigned int count, size_t priv_len ) {
+	struct gpios *gpios;
+	struct gpio *gpio;
+	size_t len;
+	unsigned int i;
+
+	/* Allocate and initialise structure */
+	len = ( sizeof ( *gpios ) + ( count * sizeof ( *gpio ) ) + priv_len );
+	gpios = zalloc ( len );
+	if ( ! gpios )
+		return NULL;
+	gpios->count = count;
+	gpios->gpio = ( ( ( void * ) gpios ) + sizeof ( *gpios ) );
+	gpios->priv = ( ( ( void * ) gpios ) + sizeof ( *gpios ) +
+			( count * sizeof ( *gpio ) ) );
+
+	/* Initialise GPIO pins */
+	for ( i = 0 ; i < count ; i++ ) {
+		gpio = &gpios->gpio[i];
+		gpio->gpios = gpios;
+		gpio->index = i;
+	}
+
+	return gpios;
+}
+
+/**
+ * Register GPIO controller
+ *
+ * @v gpios		GPIO controller
+ * @ret rc		Return status code
+ */
+int gpios_register ( struct gpios *gpios ) {
+
+	/* Add to list of GPIO controllers */
+	gpios_get ( gpios );
+	list_add_tail ( &gpios->list, &all_gpios );
+	DBGC ( gpios, "GPIO %s registered with %d GPIOs\n",
+	       gpios->dev->name, gpios->count );
+
+	return 0;
+}
+
+/**
+ * Unregister GPIO controller
+ *
+ * @v gpios		GPIO controller
+ */
+void gpios_unregister ( struct gpios *gpios ) {
+
+	/* Remove from list of GPIO controllers */
+	DBGC ( gpios, "GPIO %s unregistered\n", gpios->dev->name );
+	list_del ( &gpios->list );
+	gpios_put ( gpios );
+}
+
+/**
+ * Find GPIO controller
+ *
+ * @v bus_type		Bus type
+ * @v location		Bus location
+ * @ret gpios		GPIO controller, or NULL
+ */
+struct gpios * gpios_find ( unsigned int bus_type, unsigned int location ) {
+	struct gpios *gpios;
+
+	/* Scan through list of registered GPIO controllers */
+	list_for_each_entry ( gpios, &all_gpios, list ) {
+		if ( ( gpios->dev->desc.bus_type == bus_type ) &&
+		     ( gpios->dev->desc.location == location ) )
+			return gpios;
+	}
+
+	return NULL;
+}
+
+/**
+ * Get null GPIO input value
+ *
+ * @v gpios		GPIO controller
+ * @v gpio		GPIO pin
+ * @ret active		Pin is in the active state
+ */
+static int null_gpio_in ( struct gpios *gpios __unused,
+			  struct gpio *gpio __unused ) {
+	return 0;
+}
+
+/**
+ * Set null GPIO output value
+ *
+ * @v gpios		GPIO controller
+ * @v gpio		GPIO pin
+ * @v active		Set pin to active state
+ */
+static void null_gpio_out ( struct gpios *gpios __unused,
+			    struct gpio *gpio __unused, int active __unused ) {
+	/* Nothing to do */
+}
+
+/**
+ * Configure null GPIO pin
+ *
+ * @v gpios		GPIO controller
+ * @v gpio		GPIO pin
+ * @v config		Configuration
+ * @ret rc		Return status code
+ */
+static int null_gpio_config ( struct gpios *gpios __unused,
+			      struct gpio *gpio __unused,
+			      unsigned int config __unused ) {
+	return -ENODEV;
+}
+
+/** Null GPIO operations */
+struct gpio_operations null_gpio_operations = {
+	.in = null_gpio_in,
+	.out = null_gpio_out,
+	.config = null_gpio_config,
+};