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path: root/drivers/gpio/gpiolib-swnode.c
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Diffstat (limited to 'drivers/gpio/gpiolib-swnode.c')
-rw-r--r--drivers/gpio/gpiolib-swnode.c124
1 files changed, 124 insertions, 0 deletions
diff --git a/drivers/gpio/gpiolib-swnode.c b/drivers/gpio/gpiolib-swnode.c
new file mode 100644
index 0000000000..b5a6eaf372
--- /dev/null
+++ b/drivers/gpio/gpiolib-swnode.c
@@ -0,0 +1,124 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Software Node helpers for the GPIO API
+ *
+ * Copyright 2022 Google LLC
+ */
+#include <linux/err.h>
+#include <linux/errno.h>
+#include <linux/kernel.h>
+#include <linux/printk.h>
+#include <linux/property.h>
+#include <linux/string.h>
+
+#include <linux/gpio/consumer.h>
+#include <linux/gpio/driver.h>
+
+#include "gpiolib.h"
+#include "gpiolib-swnode.h"
+
+static void swnode_format_propname(const char *con_id, char *propname,
+ size_t max_size)
+{
+ /*
+ * Note we do not need to try both -gpios and -gpio suffixes,
+ * as, unlike OF and ACPI, we can fix software nodes to conform
+ * to the proper binding.
+ */
+ if (con_id)
+ snprintf(propname, max_size, "%s-gpios", con_id);
+ else
+ strscpy(propname, "gpios", max_size);
+}
+
+static int swnode_gpiochip_match_name(struct gpio_chip *chip, void *data)
+{
+ return !strcmp(chip->label, data);
+}
+
+static struct gpio_chip *swnode_get_chip(struct fwnode_handle *fwnode)
+{
+ const struct software_node *chip_node;
+ struct gpio_chip *chip;
+
+ chip_node = to_software_node(fwnode);
+ if (!chip_node || !chip_node->name)
+ return ERR_PTR(-EINVAL);
+
+ chip = gpiochip_find((void *)chip_node->name, swnode_gpiochip_match_name);
+ return chip ?: ERR_PTR(-EPROBE_DEFER);
+}
+
+struct gpio_desc *swnode_find_gpio(struct fwnode_handle *fwnode,
+ const char *con_id, unsigned int idx,
+ unsigned long *flags)
+{
+ const struct software_node *swnode;
+ struct fwnode_reference_args args;
+ struct gpio_chip *chip;
+ struct gpio_desc *desc;
+ char propname[32]; /* 32 is max size of property name */
+ int error;
+
+ swnode = to_software_node(fwnode);
+ if (!swnode)
+ return ERR_PTR(-EINVAL);
+
+ swnode_format_propname(con_id, propname, sizeof(propname));
+
+ /*
+ * We expect all swnode-described GPIOs have GPIO number and
+ * polarity arguments, hence nargs is set to 2.
+ */
+ error = fwnode_property_get_reference_args(fwnode, propname, NULL, 2, idx, &args);
+ if (error) {
+ pr_debug("%s: can't parse '%s' property of node '%pfwP[%d]'\n",
+ __func__, propname, fwnode, idx);
+ return ERR_PTR(error);
+ }
+
+ chip = swnode_get_chip(args.fwnode);
+ fwnode_handle_put(args.fwnode);
+ if (IS_ERR(chip))
+ return ERR_CAST(chip);
+
+ desc = gpiochip_get_desc(chip, args.args[0]);
+ *flags = args.args[1]; /* We expect native GPIO flags */
+
+ pr_debug("%s: parsed '%s' property of node '%pfwP[%d]' - status (%d)\n",
+ __func__, propname, fwnode, idx, PTR_ERR_OR_ZERO(desc));
+
+ return desc;
+}
+
+/**
+ * swnode_gpio_count - count the GPIOs associated with a device / function
+ * @fwnode: firmware node of the GPIO consumer, can be %NULL for
+ * system-global GPIOs
+ * @con_id: function within the GPIO consumer
+ *
+ * Return:
+ * The number of GPIOs associated with a device / function or %-ENOENT,
+ * if no GPIO has been assigned to the requested function.
+ */
+int swnode_gpio_count(const struct fwnode_handle *fwnode, const char *con_id)
+{
+ struct fwnode_reference_args args;
+ char propname[32];
+ int count;
+
+ swnode_format_propname(con_id, propname, sizeof(propname));
+
+ /*
+ * This is not very efficient, but GPIO lists usually have only
+ * 1 or 2 entries.
+ */
+ count = 0;
+ while (fwnode_property_get_reference_args(fwnode, propname, NULL, 0,
+ count, &args) == 0) {
+ fwnode_handle_put(args.fwnode);
+ count++;
+ }
+
+ return count ?: -ENOENT;
+}