[PATCH v10 2/5] gpio: sim: new testing module
From: Bartosz Golaszewski
Date: Wed Nov 24 2021 - 06:43:23 EST
Implement a new, modern GPIO testing module controlled by configfs
attributes instead of module parameters. The goal of this driver is
to provide a replacement for gpio-mockup that will be easily extensible
with new features and doesn't require reloading the module to change
the setup.
Signed-off-by: Bartosz Golaszewski <brgl@xxxxxxxx>
---
Documentation/admin-guide/gpio/gpio-sim.rst | 80 ++
drivers/gpio/Kconfig | 8 +
drivers/gpio/Makefile | 1 +
drivers/gpio/gpio-sim.c | 1370 +++++++++++++++++++
4 files changed, 1459 insertions(+)
create mode 100644 Documentation/admin-guide/gpio/gpio-sim.rst
create mode 100644 drivers/gpio/gpio-sim.c
diff --git a/Documentation/admin-guide/gpio/gpio-sim.rst b/Documentation/admin-guide/gpio/gpio-sim.rst
new file mode 100644
index 000000000000..5da24bc698d7
--- /dev/null
+++ b/Documentation/admin-guide/gpio/gpio-sim.rst
@@ -0,0 +1,80 @@
+.. SPDX-License-Identifier: GPL-2.0-or-later
+
+Configfs GPIO Simulator
+=======================
+
+The configfs GPIO Simulator (gpio-sim) provides a way to create simulated GPIO
+chips for testing purposes. The lines exposed by these chips can be accessed
+using the standard GPIO character device interface as well as manipulated
+using sysfs attributes.
+
+Creating simulated chips
+------------------------
+
+The gpio-sim module registers a configfs subsystem called 'gpio-sim'.
+
+In order to instantiate a new simulated chip, the user needs to mkdir() a new
+directory gpio-sim/. Inside each new directory, there's a set of attributes
+that can be used to configure the new chip. Additionally the user can mkdir()
+subdirectories inside the chip's directory that allow to pass additional
+configuration for specific lines. The name of those subdirectories must take
+the form of: 'line<offset>' (e.g. 'line0', 'line20', etc.) as the name will be
+used by the module to assign the config to the specific line at given offset.
+
+Once the confiuration is complete, the 'live' attribute must be set to 1 in
+order to instantiate the chip. It can be set back to 0 to destroy the simulated
+chip. The module will synchronously wait for the new simulated device to be
+successfully probed and if this doesn't happen, writing to 'live' will result
+in an error.
+
+Currently supported chip configuration attributes are:
+
+ num_lines - an unsigned integer value defining the number of GPIO lines to
+ export
+
+ label - a string defining the label for the GPIO chip
+
+Additionally two read-only attributes named 'chip_name' and 'dev_name' are
+exposed in order to provide users with a mapping from configfs directories to
+the actual devices created in the kernel. The former returns the name of the
+GPIO device as assigned by gpiolib (i.e. "gpiochip0", "gpiochip1", etc.). The
+latter returns the parent device name as defined by the gpio-sim driver (i.e.
+"gpio-sim.0", "gpio-sim.1", etc.). This allows user-space to map the configfs
+items both to the correct character device file as well as the associated entry
+in sysfs.
+
+Supported line configuration attributes are:
+
+ name - a string defining the name of this line as used by the
+ "gpio-line-names" device property
+
+Lines can be hogged by creating a new directory under the line's directory. The
+directory must be called 'hog' and there can only be a single instance of it.
+The hog directory also exposes additional attributes:
+
+ name - name of the kernel consumer of this hogged line
+
+ direction - hog direction, must be one of: 'input', 'output-high' and
+ 'output-low'
+
+Simulated GPIO chips can also be defined in device-tree. The compatible string
+must be: "gpio-simulator". Supported properties are:
+
+ "gpio-sim,label" - chip label
+
+Other standard GPIO properties (like "gpio-line-names", "ngpios" or gpio-hog)
+are also supported.
+
+Manipulating simulated lines
+----------------------------
+
+Each simulated GPIO chip creates a separate sysfs group under its device
+directory for each exposed line. The name of each group is of the form:
+'sim_gpioX' where X is the offset of the line. Inside each group there are
+two attibutes:
+
+ pull - allows to read and set the current simulated pull setting for every
+ line, when writing the value must be one of: 'pull-up', 'pull-down'
+
+ value - allows to read the current value of the line which may be different
+ from the pull if the line is being driven from user-space
diff --git a/drivers/gpio/Kconfig b/drivers/gpio/Kconfig
index 60d9374c72c0..9acdb4d1047b 100644
--- a/drivers/gpio/Kconfig
+++ b/drivers/gpio/Kconfig
@@ -1694,6 +1694,14 @@ config GPIO_VIRTIO
These virtual GPIOs can be routed to real GPIOs or attached to
simulators on the host (like QEMU).
+config GPIO_SIM
+ tristate "GPIO Simulator Module"
+ select IRQ_SIM
+ select CONFIGFS_FS
+ help
+ This enables the GPIO simulator - a configfs-based GPIO testing
+ driver.
+
endmenu
endif
diff --git a/drivers/gpio/Makefile b/drivers/gpio/Makefile
index 71ee9fc2ff83..f21577de2474 100644
--- a/drivers/gpio/Makefile
+++ b/drivers/gpio/Makefile
@@ -133,6 +133,7 @@ obj-$(CONFIG_GPIO_SAMA5D2_PIOBU) += gpio-sama5d2-piobu.o
obj-$(CONFIG_GPIO_SCH311X) += gpio-sch311x.o
obj-$(CONFIG_GPIO_SCH) += gpio-sch.o
obj-$(CONFIG_GPIO_SIFIVE) += gpio-sifive.o
+obj-$(CONFIG_GPIO_SIM) += gpio-sim.o
obj-$(CONFIG_GPIO_SIOX) += gpio-siox.o
obj-$(CONFIG_GPIO_SL28CPLD) += gpio-sl28cpld.o
obj-$(CONFIG_GPIO_SODAVILLE) += gpio-sodaville.o
diff --git a/drivers/gpio/gpio-sim.c b/drivers/gpio/gpio-sim.c
new file mode 100644
index 000000000000..d4ddbb4a4e3b
--- /dev/null
+++ b/drivers/gpio/gpio-sim.c
@@ -0,0 +1,1370 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * GPIO testing driver based on configfs.
+ *
+ * Copyright (C) 2021 Bartosz Golaszewski <brgl@xxxxxxxx>
+ */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/bitmap.h>
+#include <linux/completion.h>
+#include <linux/configfs.h>
+#include <linux/device.h>
+#include <linux/gpio/driver.h>
+#include <linux/gpio/machine.h>
+#include <linux/idr.h>
+#include <linux/interrupt.h>
+#include <linux/irq.h>
+#include <linux/irq_sim.h>
+#include <linux/list.h>
+#include <linux/mod_devicetable.h>
+#include <linux/module.h>
+#include <linux/mutex.h>
+#include <linux/notifier.h>
+#include <linux/platform_device.h>
+#include <linux/property.h>
+#include <linux/slab.h>
+#include <linux/string.h>
+#include <linux/string_helpers.h>
+#include <linux/sysfs.h>
+
+#include "gpiolib.h"
+
+static DEFINE_IDA(gpio_sim_ida);
+
+struct gpio_sim_chip {
+ struct gpio_chip gc;
+ unsigned long *direction_map;
+ unsigned long *value_map;
+ unsigned long *pull_map;
+ struct irq_domain *irq_sim;
+ struct mutex lock;
+ const struct attribute_group **attr_groups;
+};
+
+/* value, pull and sentinel */
+#define GPIO_SIM_NUM_ATTRS 3
+
+struct gpio_sim_attribute {
+ struct device_attribute dev_attr;
+ unsigned int offset;
+};
+
+static struct gpio_sim_attribute *
+to_gpio_sim_attr(struct device_attribute *dev_attr)
+{
+ return container_of(dev_attr, struct gpio_sim_attribute, dev_attr);
+}
+
+static int gpio_sim_apply_pull(struct gpio_sim_chip *chip,
+ unsigned int offset, int value)
+{
+ int curr_val, irq, irq_type, ret;
+ struct gpio_desc *desc;
+ struct gpio_chip *gc;
+
+ gc = &chip->gc;
+ desc = &gc->gpiodev->descs[offset];
+
+ mutex_lock(&chip->lock);
+
+ if (test_bit(FLAG_REQUESTED, &desc->flags) &&
+ !test_bit(FLAG_IS_OUT, &desc->flags)) {
+ curr_val = !!test_bit(offset, chip->value_map);
+ if (curr_val == value)
+ goto set_pull;
+
+ /*
+ * This is fine - it just means, nobody is listening
+ * for interrupts on this line, otherwise
+ * irq_create_mapping() would have been called from
+ * the to_irq() callback.
+ */
+ irq = irq_find_mapping(chip->irq_sim, offset);
+ if (!irq)
+ goto set_value;
+
+ irq_type = irq_get_trigger_type(irq);
+
+ if ((value && (irq_type & IRQ_TYPE_EDGE_RISING)) ||
+ (!value && (irq_type & IRQ_TYPE_EDGE_FALLING))) {
+ ret = irq_set_irqchip_state(irq, IRQCHIP_STATE_PENDING,
+ true);
+ if (ret)
+ goto set_pull;
+ }
+ }
+
+set_value:
+ /* Change the value unless we're actively driving the line. */
+ if (!test_bit(FLAG_REQUESTED, &desc->flags) ||
+ !test_bit(FLAG_IS_OUT, &desc->flags))
+ __assign_bit(offset, chip->value_map, value);
+
+set_pull:
+ __assign_bit(offset, chip->pull_map, value);
+ mutex_unlock(&chip->lock);
+ return 0;
+}
+
+static int gpio_sim_get(struct gpio_chip *gc, unsigned int offset)
+{
+ struct gpio_sim_chip *chip = gpiochip_get_data(gc);
+ int ret;
+
+ mutex_lock(&chip->lock);
+ ret = !!test_bit(offset, chip->value_map);
+ mutex_unlock(&chip->lock);
+
+ return ret;
+}
+
+static void gpio_sim_set(struct gpio_chip *gc, unsigned int offset, int value)
+{
+ struct gpio_sim_chip *chip = gpiochip_get_data(gc);
+
+ mutex_lock(&chip->lock);
+ __assign_bit(offset, chip->value_map, value);
+ mutex_unlock(&chip->lock);
+}
+
+static int gpio_sim_get_multiple(struct gpio_chip *gc,
+ unsigned long *mask, unsigned long *bits)
+{
+ struct gpio_sim_chip *chip = gpiochip_get_data(gc);
+
+ mutex_lock(&chip->lock);
+ bitmap_copy(bits, chip->value_map, gc->ngpio);
+ mutex_unlock(&chip->lock);
+
+ return 0;
+}
+
+static void gpio_sim_set_multiple(struct gpio_chip *gc,
+ unsigned long *mask, unsigned long *bits)
+{
+ struct gpio_sim_chip *chip = gpiochip_get_data(gc);
+
+ mutex_lock(&chip->lock);
+ bitmap_copy(chip->value_map, bits, gc->ngpio);
+ mutex_unlock(&chip->lock);
+}
+
+static int gpio_sim_direction_output(struct gpio_chip *gc,
+ unsigned int offset, int value)
+{
+ struct gpio_sim_chip *chip = gpiochip_get_data(gc);
+
+ mutex_lock(&chip->lock);
+ __clear_bit(offset, chip->direction_map);
+ __assign_bit(offset, chip->value_map, value);
+ mutex_unlock(&chip->lock);
+
+ return 0;
+}
+
+static int gpio_sim_direction_input(struct gpio_chip *gc, unsigned int offset)
+{
+ struct gpio_sim_chip *chip = gpiochip_get_data(gc);
+
+ mutex_lock(&chip->lock);
+ __set_bit(offset, chip->direction_map);
+ mutex_unlock(&chip->lock);
+
+ return 0;
+}
+
+static int gpio_sim_get_direction(struct gpio_chip *gc, unsigned int offset)
+{
+ struct gpio_sim_chip *chip = gpiochip_get_data(gc);
+ int direction;
+
+ mutex_lock(&chip->lock);
+ direction = !!test_bit(offset, chip->direction_map);
+ mutex_unlock(&chip->lock);
+
+ return direction ? GPIO_LINE_DIRECTION_IN : GPIO_LINE_DIRECTION_OUT;
+}
+
+static int gpio_sim_set_config(struct gpio_chip *gc,
+ unsigned int offset, unsigned long config)
+{
+ struct gpio_sim_chip *chip = gpiochip_get_data(gc);
+
+ switch (pinconf_to_config_param(config)) {
+ case PIN_CONFIG_BIAS_PULL_UP:
+ return gpio_sim_apply_pull(chip, offset, 1);
+ case PIN_CONFIG_BIAS_PULL_DOWN:
+ return gpio_sim_apply_pull(chip, offset, 0);
+ default:
+ break;
+ }
+
+ return -ENOTSUPP;
+}
+
+static int gpio_sim_to_irq(struct gpio_chip *gc, unsigned int offset)
+{
+ struct gpio_sim_chip *chip = gpiochip_get_data(gc);
+
+ return irq_create_mapping(chip->irq_sim, offset);
+}
+
+static void gpio_sim_free(struct gpio_chip *gc, unsigned int offset)
+{
+ struct gpio_sim_chip *chip = gpiochip_get_data(gc);
+
+ mutex_lock(&chip->lock);
+ __assign_bit(offset, chip->value_map, !!test_bit(offset, chip->pull_map));
+ mutex_unlock(&chip->lock);
+}
+
+static ssize_t gpio_sim_sysfs_val_show(struct device *dev,
+ struct device_attribute *attr, char *buf)
+{
+ struct gpio_sim_attribute *line_attr = to_gpio_sim_attr(attr);
+ struct gpio_sim_chip *chip = dev_get_drvdata(dev);
+ int val;
+
+ mutex_lock(&chip->lock);
+ val = !!test_bit(line_attr->offset, chip->value_map);
+ mutex_unlock(&chip->lock);
+
+ return sysfs_emit(buf, "%d\n", val);
+}
+
+static ssize_t gpio_sim_sysfs_val_store(struct device *dev,
+ struct device_attribute *attr,
+ const char *buf, size_t count)
+{
+ /*
+ * Not assigning this function will result in write() returning -EIO
+ * which is confusing. Return -EPERM explicitly.
+ */
+ return -EPERM;
+}
+
+static ssize_t gpio_sim_sysfs_pull_show(struct device *dev,
+ struct device_attribute *attr,
+ char *buf)
+{
+ struct gpio_sim_attribute *line_attr = to_gpio_sim_attr(attr);
+ struct gpio_sim_chip *chip = dev_get_drvdata(dev);
+ char *repr;
+ int pull;
+
+ mutex_lock(&chip->lock);
+ pull = !!test_bit(line_attr->offset, chip->pull_map);
+ mutex_unlock(&chip->lock);
+
+ if (pull)
+ repr = "pull-up";
+ else
+ repr = "pull-down";
+
+ return sysfs_emit(buf, "%s\n", repr);
+}
+
+static ssize_t gpio_sim_sysfs_pull_store(struct device *dev,
+ struct device_attribute *attr,
+ const char *buf, size_t len)
+{
+ struct gpio_sim_attribute *line_attr = to_gpio_sim_attr(attr);
+ struct gpio_sim_chip *chip = dev_get_drvdata(dev);
+ int ret, pull;
+
+ if (sysfs_streq(buf, "pull-down"))
+ pull = 0;
+ else if (sysfs_streq(buf, "pull-up"))
+ pull = 1;
+ else
+ return -EINVAL;
+
+ ret = gpio_sim_apply_pull(chip, line_attr->offset, pull);
+ if (ret)
+ return ret;
+
+ return len;
+}
+
+static void gpio_sim_mutex_destroy(void *data)
+{
+ struct mutex *lock = data;
+
+ mutex_destroy(lock);
+}
+
+static void gpio_sim_sysfs_remove(void *data)
+{
+ struct gpio_sim_chip *chip = data;
+
+ sysfs_remove_groups(&chip->gc.parent->kobj, chip->attr_groups);
+}
+
+static int gpio_sim_setup_sysfs(struct gpio_sim_chip *chip)
+{
+ struct device_attribute *val_dev_attr, *pull_dev_attr;
+ struct gpio_sim_attribute *val_attr, *pull_attr;
+ unsigned int num_lines = chip->gc.ngpio;
+ struct device *dev = chip->gc.parent;
+ struct attribute_group *attr_group;
+ struct attribute **attrs;
+ int i, ret;
+
+ chip->attr_groups = devm_kcalloc(dev, sizeof(*chip->attr_groups),
+ num_lines + 1, GFP_KERNEL);
+ if (!chip->attr_groups)
+ return -ENOMEM;
+
+ for (i = 0; i < num_lines; i++) {
+ attr_group = devm_kzalloc(dev, sizeof(*attr_group), GFP_KERNEL);
+ attrs = devm_kcalloc(dev, sizeof(*attrs),
+ GPIO_SIM_NUM_ATTRS, GFP_KERNEL);
+ val_attr = devm_kzalloc(dev, sizeof(*val_attr), GFP_KERNEL);
+ pull_attr = devm_kzalloc(dev, sizeof(*pull_attr), GFP_KERNEL);
+ if (!attr_group || !attrs || !val_attr || !pull_attr)
+ return -ENOMEM;
+
+ attr_group->name = devm_kasprintf(dev, GFP_KERNEL,
+ "sim_gpio%u", i);
+ if (!attr_group->name)
+ return -ENOMEM;
+
+ val_attr->offset = pull_attr->offset = i;
+
+ val_dev_attr = &val_attr->dev_attr;
+ pull_dev_attr = &pull_attr->dev_attr;
+
+ sysfs_attr_init(&val_dev_attr->attr);
+ sysfs_attr_init(&pull_dev_attr->attr);
+
+ val_dev_attr->attr.name = "value";
+ pull_dev_attr->attr.name = "pull";
+
+ val_dev_attr->attr.mode = pull_dev_attr->attr.mode = 0644;
+
+ val_dev_attr->show = gpio_sim_sysfs_val_show;
+ val_dev_attr->store = gpio_sim_sysfs_val_store;
+ pull_dev_attr->show = gpio_sim_sysfs_pull_show;
+ pull_dev_attr->store = gpio_sim_sysfs_pull_store;
+
+ attrs[0] = &val_dev_attr->attr;
+ attrs[1] = &pull_dev_attr->attr;
+
+ attr_group->attrs = attrs;
+ chip->attr_groups[i] = attr_group;
+ }
+
+ ret = sysfs_create_groups(&dev->kobj, chip->attr_groups);
+ if (ret)
+ return ret;
+
+ return devm_add_action_or_reset(dev, gpio_sim_sysfs_remove, chip);
+}
+
+static int gpio_sim_probe(struct platform_device *pdev)
+{
+ struct device *dev = &pdev->dev;
+ struct gpio_sim_chip *chip;
+ struct gpio_chip *gc;
+ const char *label;
+ u32 num_lines;
+ int ret;
+
+ ret = device_property_read_u32(dev, "ngpios", &num_lines);
+ if (ret)
+ return ret;
+
+ ret = device_property_read_string(dev, "gpio-sim,label", &label);
+ if (ret)
+ label = dev_name(dev);
+
+ chip = devm_kzalloc(dev, sizeof(*chip), GFP_KERNEL);
+ if (!chip)
+ return -ENOMEM;
+
+ chip->direction_map = devm_bitmap_alloc(dev, num_lines, GFP_KERNEL);
+ if (!chip->direction_map)
+ return -ENOMEM;
+
+ /* Default to input mode. */
+ bitmap_fill(chip->direction_map, num_lines);
+
+ chip->value_map = devm_bitmap_zalloc(dev, num_lines, GFP_KERNEL);
+ if (!chip->value_map)
+ return -ENOMEM;
+
+ chip->pull_map = devm_bitmap_zalloc(dev, num_lines, GFP_KERNEL);
+ if (!chip->pull_map)
+ return -ENOMEM;
+
+ chip->irq_sim = devm_irq_domain_create_sim(dev, NULL, num_lines);
+ if (IS_ERR(chip->irq_sim))
+ return PTR_ERR(chip->irq_sim);
+
+ mutex_init(&chip->lock);
+ ret = devm_add_action_or_reset(dev, gpio_sim_mutex_destroy,
+ &chip->lock);
+ if (ret)
+ return ret;
+
+ gc = &chip->gc;
+ gc->base = -1;
+ gc->ngpio = num_lines;
+ gc->label = label;
+ gc->owner = THIS_MODULE;
+ gc->parent = dev;
+ gc->get = gpio_sim_get;
+ gc->set = gpio_sim_set;
+ gc->get_multiple = gpio_sim_get_multiple;
+ gc->set_multiple = gpio_sim_set_multiple;
+ gc->direction_output = gpio_sim_direction_output;
+ gc->direction_input = gpio_sim_direction_input;
+ gc->get_direction = gpio_sim_get_direction;
+ gc->set_config = gpio_sim_set_config;
+ gc->to_irq = gpio_sim_to_irq;
+ gc->free = gpio_sim_free;
+
+ ret = devm_gpiochip_add_data(dev, gc, chip);
+ if (ret)
+ return ret;
+
+ /* Used by sysfs and configfs callbacks. */
+ dev_set_drvdata(dev, chip);
+
+ return gpio_sim_setup_sysfs(chip);
+}
+
+static const struct of_device_id gpio_sim_of_match[] = {
+ { .compatible = "gpio-simulator" },
+ { }
+};
+MODULE_DEVICE_TABLE(of, gpio_sim_of_match);
+
+static struct platform_driver gpio_sim_driver = {
+ .driver = {
+ .name = "gpio-sim",
+ .of_match_table = gpio_sim_of_match,
+ },
+ .probe = gpio_sim_probe,
+};
+
+struct gpio_sim_chip_ctx {
+ struct config_group group;
+
+ /*
+ * If pdev is NULL, the item is 'pending' (waiting for configuration).
+ * Once the pointer is assigned, the device has been created and the
+ * item is 'live'.
+ */
+ struct platform_device *pdev;
+ int id;
+
+ /*
+ * Each configfs filesystem operation is protected with the subsystem
+ * mutex. Each separate attribute is protected with the buffer mutex.
+ * This structure however can be modified by callbacks of different
+ * attributes so we need another lock.
+ *
+ * We use this lock fo protecting all line context structures owned by
+ * this object too.
+ */
+ struct mutex lock;
+
+ char label[32];
+ unsigned int num_lines;
+
+ struct list_head line_ctx_list;
+
+ struct notifier_block bus_notifier;
+ struct completion probe_completion;
+ bool driver_bound;
+
+ struct gpiod_hog *hogs;
+};
+
+static struct gpio_sim_chip_ctx *
+gpio_sim_item_to_chip_ctx(struct config_item *item)
+{
+ struct config_group *group = to_config_group(item);
+ return container_of(group, struct gpio_sim_chip_ctx, group);
+}
+
+static struct gpio_sim_chip_ctx *
+gpio_sim_nb_to_chip_ctx(struct notifier_block *nb)
+{
+ return container_of(nb, struct gpio_sim_chip_ctx, bus_notifier);
+}
+
+/* This is called with ctx->lock taken. */
+static int gpio_sim_bus_notifier_call(struct notifier_block *nb,
+ unsigned long action, void *data)
+{
+ struct gpio_sim_chip_ctx *ctx = gpio_sim_nb_to_chip_ctx(nb);
+ struct device *dev = data;
+ char devname[32];
+
+ snprintf(devname, sizeof(devname), "gpio-sim.%u", ctx->id);
+
+ if (strcmp(dev_name(dev), devname) == 0) {
+ if (action == BUS_NOTIFY_BOUND_DRIVER)
+ ctx->driver_bound = true;
+ else if (action == BUS_NOTIFY_DRIVER_NOT_BOUND)
+ ctx->driver_bound = false;
+ else
+ return NOTIFY_DONE;
+
+ complete(&ctx->probe_completion);
+ return NOTIFY_OK;
+ }
+
+ return NOTIFY_DONE;
+}
+
+struct gpio_sim_line_ctx {
+ struct config_group group;
+ struct list_head list;
+
+ /*
+ * We could have used the ci_parent field of the config_item but
+ * configfs is stupid and calls the item's release callback after
+ * already having cleared the parent pointer even though the parent
+ * is guaranteed to survive the child...
+ *
+ * So we need to store the pointer to the parent struct here. We can
+ * dereference it anywhere we need with no checks and no locking as
+ * it's guaranteed to survive the childred and protected by configfs
+ * locks.
+ */
+ struct gpio_sim_chip_ctx *parent;
+
+ unsigned int offset;
+ char *name;
+
+ /*
+ * There can only be one hog per line so we're reusing the line context
+ * structure in order to simplify the code and avoid a whole new
+ * allocation and object management.
+ */
+ struct config_item hog_item;
+ bool hogged;
+ char *hog_name;
+ int hog_dir;
+};
+
+static struct gpio_sim_line_ctx *
+gpio_sim_item_to_line_ctx(struct config_item *item)
+{
+ struct config_group *group = to_config_group(item);
+
+ return container_of(group, struct gpio_sim_line_ctx, group);
+}
+
+static struct gpio_sim_line_ctx *
+gpio_sim_hog_item_to_line_ctx(struct config_item *item)
+{
+ return container_of(item, struct gpio_sim_line_ctx, hog_item);
+}
+
+static bool gpio_sim_chip_live(struct gpio_sim_chip_ctx *ctx)
+{
+ return !!ctx->pdev;
+}
+
+static char *gpio_sim_strdup_trimmed(const char *str, size_t count)
+{
+ char *dup, *trimmed, *ret;
+
+ dup = kstrndup(str, count, GFP_KERNEL);
+ if (!dup)
+ return NULL;
+
+ trimmed = strstrip(dup);
+ ret = kstrdup(trimmed, GFP_KERNEL);
+ kfree(dup);
+ return ret;
+}
+
+static ssize_t gpio_sim_config_chip_dev_name_show(struct config_item *item,
+ char *page)
+{
+ struct gpio_sim_chip_ctx *ctx = gpio_sim_item_to_chip_ctx(item);
+ struct platform_device *pdev;
+ int ret;
+
+ mutex_lock(&ctx->lock);
+ pdev = ctx->pdev;
+ if (pdev)
+ ret = sprintf(page, "%s\n", dev_name(&pdev->dev));
+ else
+ ret = sprintf(page, "gpio-sim.%d\n", ctx->id);
+ mutex_unlock(&ctx->lock);
+
+ return ret;
+}
+
+CONFIGFS_ATTR_RO(gpio_sim_config_chip_, dev_name);
+
+static ssize_t gpio_sim_config_chip_chip_name_show(struct config_item *item,
+ char *page)
+{
+ struct gpio_sim_chip_ctx *ctx = gpio_sim_item_to_chip_ctx(item);
+ struct gpio_sim_chip *chip = NULL;
+ int ret;
+
+ mutex_lock(&ctx->lock);
+ if (gpio_sim_chip_live(ctx))
+ chip = dev_get_drvdata(&ctx->pdev->dev);
+
+ if (chip)
+ ret = sprintf(page, "%s\n", dev_name(&chip->gc.gpiodev->dev));
+ else
+ ret = sprintf(page, "none\n");
+ mutex_unlock(&ctx->lock);
+
+ return ret;
+}
+
+CONFIGFS_ATTR_RO(gpio_sim_config_chip_, chip_name);
+
+static ssize_t
+gpio_sim_config_chip_label_show(struct config_item *item, char *page)
+{
+ struct gpio_sim_chip_ctx *ctx = gpio_sim_item_to_chip_ctx(item);
+ int ret;
+
+ mutex_lock(&ctx->lock);
+ ret = sprintf(page, "%s\n", ctx->label);
+ mutex_unlock(&ctx->lock);
+
+ return ret;
+}
+
+static ssize_t gpio_sim_config_chip_label_store(struct config_item *item,
+ const char *page, size_t count)
+{
+ struct gpio_sim_chip_ctx *ctx = gpio_sim_item_to_chip_ctx(item);
+ char *trimmed;
+ int ret;
+
+ mutex_lock(&ctx->lock);
+
+ if (gpio_sim_chip_live(ctx)) {
+ mutex_unlock(&ctx->lock);
+ return -EBUSY;
+ }
+
+ trimmed = gpio_sim_strdup_trimmed(page, count);
+ if (!trimmed) {
+ mutex_unlock(&ctx->lock);
+ return -ENOMEM;
+ }
+
+ ret = snprintf(ctx->label, sizeof(ctx->label), "%s", trimmed);
+ kfree(trimmed);
+ if (ret < 0) {
+ mutex_unlock(&ctx->lock);
+ return ret;
+ }
+
+ mutex_unlock(&ctx->lock);
+ return count;
+}
+
+CONFIGFS_ATTR(gpio_sim_config_chip_, label);
+
+static ssize_t
+gpio_sim_config_chip_num_lines_show(struct config_item *item, char *page)
+{
+ struct gpio_sim_chip_ctx *ctx = gpio_sim_item_to_chip_ctx(item);
+ int ret;
+
+ mutex_lock(&ctx->lock);
+ ret = sprintf(page, "%u\n", ctx->num_lines);
+ mutex_unlock(&ctx->lock);
+
+ return ret;
+}
+
+static ssize_t
+gpio_sim_config_chip_num_lines_store(struct config_item *item,
+ const char *page, size_t count)
+{
+ struct gpio_sim_chip_ctx *ctx = gpio_sim_item_to_chip_ctx(item);
+ unsigned int num_lines;
+ int ret;
+
+ mutex_lock(&ctx->lock);
+
+ if (gpio_sim_chip_live(ctx)) {
+ mutex_unlock(&ctx->lock);
+ return -EBUSY;
+ }
+
+ ret = kstrtouint(page, 10, &num_lines);
+ if (ret) {
+ mutex_unlock(&ctx->lock);
+ return ret;
+ }
+
+ if (num_lines == 0) {
+ mutex_unlock(&ctx->lock);
+ return -EINVAL;
+ }
+
+ ctx->num_lines = num_lines;
+
+ mutex_unlock(&ctx->lock);
+ return count;
+}
+
+CONFIGFS_ATTR(gpio_sim_config_chip_, num_lines);
+
+static ssize_t
+gpio_sim_config_chip_live_show(struct config_item *item, char *page)
+{
+ struct gpio_sim_chip_ctx *ctx = gpio_sim_item_to_chip_ctx(item);
+ int ret;
+
+ mutex_lock(&ctx->lock);
+ ret = sprintf(page, "%c\n", gpio_sim_chip_live(ctx) ? '1' : '0');
+ mutex_unlock(&ctx->lock);
+
+ return ret;
+}
+
+static char **gpio_sim_make_line_names(struct gpio_sim_chip_ctx *chip_ctx,
+ unsigned int *line_names_size)
+{
+ struct gpio_sim_line_ctx *line_ctx;
+ unsigned int max_offset = 0;
+ bool has_line_names = false;
+ char **line_names;
+
+ list_for_each_entry(line_ctx, &chip_ctx->line_ctx_list, list) {
+ if (line_ctx->name) {
+ if (line_ctx->offset > max_offset)
+ max_offset = line_ctx->offset;
+
+ /*
+ * max_offset can stay at 0 so it's not an indicator
+ * of whether line names were configured at all.
+ */
+ has_line_names = true;
+ }
+ }
+
+ if (!has_line_names)
+ /*
+ * This is not an error - NULL means, there are no line
+ * names configured.
+ */
+ return NULL;
+
+ *line_names_size = max_offset + 1;
+
+ line_names = kcalloc(*line_names_size, sizeof(*line_names), GFP_KERNEL);
+ if (!line_names)
+ return ERR_PTR(-ENOMEM);
+
+ list_for_each_entry(line_ctx, &chip_ctx->line_ctx_list, list)
+ line_names[line_ctx->offset] = line_ctx->name;
+
+ return line_names;
+}
+
+static void gpio_sim_remove_hogs(struct gpio_sim_chip_ctx *ctx)
+{
+ struct gpiod_hog *hog;
+
+ if (!ctx->hogs)
+ return;
+
+ gpiod_remove_hogs(ctx->hogs);
+
+ for (hog = ctx->hogs; !hog->chip_label; hog++) {
+ kfree(hog->chip_label);
+ kfree(hog->line_name);
+ }
+
+ kfree(ctx->hogs);
+ ctx->hogs = NULL;
+}
+
+static int gpio_sim_add_hogs(struct gpio_sim_chip_ctx *chip_ctx)
+{
+ struct gpio_sim_line_ctx *line_ctx;
+ unsigned int num_hogs = 0, idx = 0;
+ struct gpiod_hog *hog;
+
+ list_for_each_entry(line_ctx, &chip_ctx->line_ctx_list, list) {
+ if (line_ctx->hogged)
+ num_hogs++;
+ }
+
+ if (!num_hogs)
+ return 0;
+
+ /* Allocate one more for the sentinel. */
+ chip_ctx->hogs = kcalloc(num_hogs + 1,
+ sizeof(*chip_ctx->hogs), GFP_KERNEL);
+ if (!chip_ctx->hogs)
+ return -ENOMEM;
+
+ list_for_each_entry(line_ctx, &chip_ctx->line_ctx_list, list) {
+ hog = &chip_ctx->hogs[idx++];
+
+ /*
+ * We need to make this string manually because at this point
+ * the device doesn't exist yet and so dev_name() is not
+ * available.
+ */
+ hog->chip_label = kasprintf(GFP_KERNEL,
+ "gpio-sim.%u", chip_ctx->id);
+ if (!hog->chip_label) {
+ gpio_sim_remove_hogs(chip_ctx);
+ return -ENOMEM;
+ }
+
+ /*
+ * We need to duplicate this because the hog config item can
+ * be removed at any time (and we can't block it) and gpiolib
+ * doesn't make a deep copy of the hog data.
+ */
+ if (line_ctx->hog_name) {
+ hog->line_name = kstrdup(line_ctx->hog_name,
+ GFP_KERNEL);
+ if (!hog->line_name) {
+ gpio_sim_remove_hogs(chip_ctx);
+ return -ENOMEM;
+ }
+ }
+
+ hog->chip_hwnum = line_ctx->offset;
+ hog->dflags = line_ctx->hog_dir;
+ }
+
+ gpiod_add_hogs(chip_ctx->hogs);
+
+ return 0;
+}
+
+static int gpio_sim_activate_chip_unlocked(struct gpio_sim_chip_ctx *ctx)
+{
+ unsigned int prop_idx = 0, line_names_size = 0;
+ struct platform_device_info pdevinfo;
+ struct property_entry properties[4]; /* Max 3 properties + sentinel. */
+ struct fwnode_handle *fwnode;
+ struct platform_device *pdev;
+ char **line_names;
+ int ret;
+
+ memset(&pdevinfo, 0, sizeof(pdevinfo));
+ memset(properties, 0, sizeof(properties));
+
+ properties[prop_idx++] = PROPERTY_ENTRY_U32("ngpios",
+ ctx->num_lines);
+
+ if (ctx->label[0] != '\0')
+ properties[prop_idx++] = PROPERTY_ENTRY_STRING("gpio-sim,label",
+ ctx->label);
+
+ line_names = gpio_sim_make_line_names(ctx, &line_names_size);
+ if (IS_ERR(line_names))
+ return PTR_ERR(line_names);
+
+ if (line_names)
+ properties[prop_idx++] = PROPERTY_ENTRY_STRING_ARRAY_LEN(
+ "gpio-line-names",
+ line_names, line_names_size);
+
+ fwnode = fwnode_create_software_node(properties, NULL);
+ kfree(line_names);
+ if (IS_ERR(fwnode))
+ return PTR_ERR(fwnode);
+
+ ret = gpio_sim_add_hogs(ctx);
+ if (ret) {
+ fwnode_remove_software_node(fwnode);
+ return ret;
+ }
+
+ pdevinfo.name = "gpio-sim";
+ pdevinfo.fwnode = fwnode;
+ pdevinfo.id = ctx->id;
+
+ reinit_completion(&ctx->probe_completion);
+ ctx->driver_bound = false;
+ bus_register_notifier(&platform_bus_type, &ctx->bus_notifier);
+
+ pdev = platform_device_register_full(&pdevinfo);
+ if (IS_ERR(pdev)) {
+ bus_unregister_notifier(&platform_bus_type, &ctx->bus_notifier);
+ gpio_sim_remove_hogs(ctx);
+ fwnode_remove_software_node(fwnode);
+ return PTR_ERR(pdev);
+ }
+
+ wait_for_completion(&ctx->probe_completion);
+ bus_unregister_notifier(&platform_bus_type, &ctx->bus_notifier);
+
+ if (!ctx->driver_bound) {
+ /* Probe failed, check kernel log. */
+ platform_device_unregister(pdev);
+ gpio_sim_remove_hogs(ctx);
+ fwnode_remove_software_node(fwnode);
+ return -ENXIO;
+ }
+
+ ctx->pdev = pdev;
+
+ return 0;
+}
+
+static void gpio_sim_deactivate_chip_unlocked(struct gpio_sim_chip_ctx *ctx)
+{
+ struct fwnode_handle *fwnode;
+
+ fwnode = dev_fwnode(&ctx->pdev->dev);
+ platform_device_unregister(ctx->pdev);
+ fwnode_remove_software_node(fwnode);
+ ctx->pdev = NULL;
+ gpio_sim_remove_hogs(ctx);
+}
+
+static ssize_t
+gpio_sim_config_chip_live_store(struct config_item *item,
+ const char *page, size_t count)
+{
+ struct gpio_sim_chip_ctx *ctx = gpio_sim_item_to_chip_ctx(item);
+ int live, ret;
+
+ ret = kstrtouint(page, 10, &live);
+ if (ret)
+ return ret;
+
+ mutex_lock(&ctx->lock);
+
+ if ((live == 0 && !gpio_sim_chip_live(ctx)) ||
+ (live == 1 && gpio_sim_chip_live(ctx)))
+ ret = -EPERM;
+ else if (live == 1)
+ ret = gpio_sim_activate_chip_unlocked(ctx);
+ else if (live == 0)
+ gpio_sim_deactivate_chip_unlocked(ctx);
+ else
+ ret = -EINVAL;
+
+ mutex_unlock(&ctx->lock);
+
+ return ret ?: count;
+}
+
+CONFIGFS_ATTR(gpio_sim_config_chip_, live);
+
+static struct configfs_attribute *gpio_sim_config_chip_attrs[] = {
+ &gpio_sim_config_chip_attr_dev_name,
+ &gpio_sim_config_chip_attr_chip_name,
+ &gpio_sim_config_chip_attr_label,
+ &gpio_sim_config_chip_attr_num_lines,
+ &gpio_sim_config_chip_attr_live,
+ NULL
+};
+
+static ssize_t
+gpio_sim_config_line_name_show(struct config_item *item, char *page)
+{
+ struct gpio_sim_line_ctx *ctx = gpio_sim_item_to_line_ctx(item);
+ int ret;
+
+ mutex_lock(&ctx->parent->lock);
+ ret = sprintf(page, "%s\n", ctx->name ?: "");
+ mutex_unlock(&ctx->parent->lock);
+
+ return ret;
+}
+
+static ssize_t gpio_sim_config_line_name_store(struct config_item *item,
+ const char *page, size_t count)
+{
+ struct gpio_sim_line_ctx *ctx = gpio_sim_item_to_line_ctx(item);
+ char *trimmed;
+
+ mutex_lock(&ctx->parent->lock);
+
+ if (gpio_sim_chip_live(ctx->parent)) {
+ mutex_unlock(&ctx->parent->lock);
+ return -EBUSY;
+ }
+
+ trimmed = gpio_sim_strdup_trimmed(page, count);
+ if (!trimmed) {
+ mutex_unlock(&ctx->parent->lock);
+ return -ENOMEM;
+ }
+
+ kfree(ctx->name);
+ ctx->name = trimmed;
+
+ mutex_unlock(&ctx->parent->lock);
+
+ return count;
+}
+
+CONFIGFS_ATTR(gpio_sim_config_line_, name);
+
+static struct configfs_attribute *gpio_sim_config_line_attrs[] = {
+ &gpio_sim_config_line_attr_name,
+ NULL,
+};
+
+static ssize_t gpio_sim_config_hog_name_show(struct config_item *item,
+ char *page)
+{
+ struct gpio_sim_line_ctx *ctx = gpio_sim_hog_item_to_line_ctx(item);
+ int ret;
+
+ mutex_lock(&ctx->parent->lock);
+ ret = sprintf(page, "%s\n", ctx->hog_name ?: "");
+ mutex_unlock(&ctx->parent->lock);
+
+ return ret;
+}
+
+static ssize_t gpio_sim_config_hog_name_store(struct config_item *item,
+ const char *page, size_t count)
+{
+ struct gpio_sim_line_ctx *ctx = gpio_sim_hog_item_to_line_ctx(item);
+ char *trimmed;
+
+ mutex_lock(&ctx->parent->lock);
+
+ if (gpio_sim_chip_live(ctx->parent)) {
+ mutex_unlock(&ctx->parent->lock);
+ return -EBUSY;
+ }
+
+ trimmed = gpio_sim_strdup_trimmed(page, count);
+ if (!trimmed) {
+ mutex_unlock(&ctx->parent->lock);
+ return -ENOMEM;
+ }
+
+ kfree(ctx->hog_name);
+ ctx->hog_name = trimmed;
+
+ mutex_unlock(&ctx->parent->lock);
+
+ return count;
+}
+
+CONFIGFS_ATTR(gpio_sim_config_hog_, name);
+
+static ssize_t gpio_sim_config_hog_direction_show(struct config_item *item,
+ char *page)
+{
+ struct gpio_sim_line_ctx *ctx = gpio_sim_hog_item_to_line_ctx(item);
+ char *repr;
+ int dir;
+
+ mutex_lock(&ctx->parent->lock);
+ dir = ctx->hog_dir;
+ mutex_unlock(&ctx->parent->lock);
+
+ switch (dir) {
+ case GPIOD_IN:
+ repr = "input";
+ break;
+ case GPIOD_OUT_HIGH:
+ repr = "output-high";
+ break;
+ case GPIOD_OUT_LOW:
+ repr = "output-low";
+ break;
+ default:
+ WARN(1, "Unexpected hog direction value: %d", dir);
+ break;
+ }
+
+ return sprintf(page, "%s\n", repr);
+}
+
+static ssize_t
+gpio_sim_config_hog_direction_store(struct config_item *item,
+ const char *page, size_t count)
+{
+ struct gpio_sim_line_ctx *ctx = gpio_sim_hog_item_to_line_ctx(item);
+ char *trimmed;
+ int dir;
+
+ mutex_lock(&ctx->parent->lock);
+
+ if (gpio_sim_chip_live(ctx->parent)) {
+ mutex_unlock(&ctx->parent->lock);
+ return -EBUSY;
+ }
+
+ trimmed = gpio_sim_strdup_trimmed(page, count);
+ if (!trimmed) {
+ mutex_unlock(&ctx->parent->lock);
+ return -ENOMEM;
+ }
+
+ if (strcmp(trimmed, "input") == 0)
+ dir = GPIOD_IN;
+ else if (strcmp(trimmed, "output-high") == 0)
+ dir = GPIOD_OUT_HIGH;
+ else if (strcmp(trimmed, "output-low") == 0)
+ dir = GPIOD_OUT_LOW;
+ else
+ dir = -EINVAL;
+
+ kfree(trimmed);
+
+ if (dir < 0) {
+ mutex_unlock(&ctx->parent->lock);
+ return dir;
+ }
+
+ ctx->hog_dir = dir;
+
+ mutex_unlock(&ctx->parent->lock);
+
+ return count;
+}
+
+CONFIGFS_ATTR(gpio_sim_config_hog_, direction);
+
+static struct configfs_attribute *gpio_sim_config_hog_attrs[] = {
+ &gpio_sim_config_hog_attr_name,
+ &gpio_sim_config_hog_attr_direction,
+ NULL,
+};
+
+static void gpio_sim_config_hog_item_release(struct config_item *item)
+{
+ struct gpio_sim_line_ctx *ctx = gpio_sim_hog_item_to_line_ctx(item);
+
+ mutex_lock(&ctx->parent->lock);
+ ctx->hogged = false;
+ kfree(ctx->hog_name);
+ mutex_unlock(&ctx->parent->lock);
+}
+
+struct configfs_item_operations gpio_sim_config_hog_item_ops = {
+ .release = gpio_sim_config_hog_item_release,
+};
+
+static const struct config_item_type gpio_sim_config_hog_type = {
+ .ct_item_ops = &gpio_sim_config_hog_item_ops,
+ .ct_attrs = gpio_sim_config_hog_attrs,
+ .ct_owner = THIS_MODULE,
+};
+
+static struct config_item *
+gpio_sim_config_make_hog_item(struct config_group *group, const char *name)
+{
+ struct gpio_sim_line_ctx *ctx = gpio_sim_item_to_line_ctx(&group->cg_item);
+
+ mutex_lock(&ctx->parent->lock);
+
+ ctx->hogged = true;
+ ctx->hog_dir = GPIOD_IN;
+ ctx->hog_name = NULL;
+
+ config_item_init_type_name(&ctx->hog_item, name,
+ &gpio_sim_config_hog_type);
+
+ mutex_unlock(&ctx->parent->lock);
+
+ return &ctx->hog_item;
+}
+
+static struct config_item *
+gpio_sim_config_make_line_item(struct config_group *group, const char *name)
+{
+ if (strcmp(name, "hog") == 0)
+ return gpio_sim_config_make_hog_item(group, name);
+
+ return ERR_PTR(-EINVAL);
+}
+
+static void gpio_sim_config_line_group_release(struct config_item *item)
+{
+ struct gpio_sim_line_ctx *ctx = gpio_sim_item_to_line_ctx(item);
+
+ mutex_lock(&ctx->parent->lock);
+ list_del(&ctx->list);
+ mutex_unlock(&ctx->parent->lock);
+
+ kfree(ctx->name);
+ kfree(ctx);
+}
+
+static struct configfs_item_operations gpio_sim_config_line_item_ops = {
+ .release = gpio_sim_config_line_group_release,
+};
+
+static struct configfs_group_operations gpio_sim_config_line_group_ops = {
+ .make_item = gpio_sim_config_make_line_item,
+};
+
+static const struct config_item_type gpio_sim_config_line_type = {
+ .ct_item_ops = &gpio_sim_config_line_item_ops,
+ .ct_group_ops = &gpio_sim_config_line_group_ops,
+ .ct_attrs = gpio_sim_config_line_attrs,
+ .ct_owner = THIS_MODULE,
+};
+
+static struct config_group *
+gpio_sim_config_make_line_group(struct config_group *group, const char *name)
+{
+ struct gpio_sim_chip_ctx *chip_ctx;
+ struct gpio_sim_line_ctx *line_ctx;
+ unsigned int offset;
+ int ret, nchar;
+
+ ret = sscanf(name, "line%u%n", &offset, &nchar);
+ if (ret != 1 || nchar != strlen(name))
+ return ERR_PTR(-EINVAL);
+
+ chip_ctx = gpio_sim_item_to_chip_ctx(&group->cg_item);
+
+ mutex_lock(&chip_ctx->lock);
+
+ if (gpio_sim_chip_live(chip_ctx)) {
+ mutex_unlock(&chip_ctx->lock);
+ return ERR_PTR(-EBUSY);
+ }
+
+ line_ctx = kzalloc(sizeof(*line_ctx), GFP_KERNEL);
+ if (!line_ctx) {
+ mutex_unlock(&chip_ctx->lock);
+ return ERR_PTR(-ENOMEM);
+ }
+
+ config_group_init_type_name(&line_ctx->group, name,
+ &gpio_sim_config_line_type);
+
+ line_ctx->parent = chip_ctx;
+ line_ctx->offset = offset;
+ list_add_tail(&line_ctx->list, &chip_ctx->line_ctx_list);
+
+ mutex_unlock(&chip_ctx->lock);
+
+ return &line_ctx->group;
+}
+
+static void gpio_sim_config_chip_group_release(struct config_item *item)
+{
+ struct gpio_sim_chip_ctx *ctx = gpio_sim_item_to_chip_ctx(item);
+
+ mutex_lock(&ctx->lock);
+ if (gpio_sim_chip_live(ctx))
+ gpio_sim_deactivate_chip_unlocked(ctx);
+ mutex_unlock(&ctx->lock);
+
+ mutex_destroy(&ctx->lock);
+ ida_free(&gpio_sim_ida, ctx->id);
+ kfree(ctx);
+}
+
+static struct configfs_item_operations gpio_sim_config_chip_item_ops = {
+ .release = gpio_sim_config_chip_group_release,
+};
+
+static struct configfs_group_operations gpio_sim_config_chip_group_ops = {
+ .make_group = gpio_sim_config_make_line_group,
+};
+
+static const struct config_item_type gpio_sim_config_chip_group_type = {
+ .ct_item_ops = &gpio_sim_config_chip_item_ops,
+ .ct_group_ops = &gpio_sim_config_chip_group_ops,
+ .ct_attrs = gpio_sim_config_chip_attrs,
+ .ct_owner = THIS_MODULE,
+};
+
+static struct config_group *
+gpio_sim_config_make_chip_group(struct config_group *group, const char *name)
+{
+ struct gpio_sim_chip_ctx *ctx;
+ int id;
+
+ ctx = kzalloc(sizeof(*ctx), GFP_KERNEL);
+ if (!ctx)
+ return ERR_PTR(-ENOMEM);
+
+ id = ida_alloc(&gpio_sim_ida, GFP_KERNEL);
+ if (id < 0) {
+ kfree(ctx);
+ return ERR_PTR(id);
+ }
+
+ config_group_init_type_name(&ctx->group, name,
+ &gpio_sim_config_chip_group_type);
+ ctx->num_lines = 1;
+ ctx->id = id;
+ mutex_init(&ctx->lock);
+ INIT_LIST_HEAD(&ctx->line_ctx_list);
+
+ ctx->bus_notifier.notifier_call = gpio_sim_bus_notifier_call;
+ init_completion(&ctx->probe_completion);
+
+ return &ctx->group;
+}
+
+static struct configfs_group_operations gpio_sim_config_group_ops = {
+ .make_group = gpio_sim_config_make_chip_group,
+};
+
+static const struct config_item_type gpio_sim_config_type = {
+ .ct_group_ops = &gpio_sim_config_group_ops,
+ .ct_owner = THIS_MODULE,
+};
+
+static struct configfs_subsystem gpio_sim_config_subsys = {
+ .su_group = {
+ .cg_item = {
+ .ci_namebuf = "gpio-sim",
+ .ci_type = &gpio_sim_config_type,
+ },
+ },
+};
+
+static int __init gpio_sim_init(void)
+{
+ int ret;
+
+ ret = platform_driver_register(&gpio_sim_driver);
+ if (ret) {
+ pr_err("Error %d while registering the platform driver\n", ret);
+ return ret;
+ }
+
+ config_group_init(&gpio_sim_config_subsys.su_group);
+ mutex_init(&gpio_sim_config_subsys.su_mutex);
+ ret = configfs_register_subsystem(&gpio_sim_config_subsys);
+ if (ret) {
+ pr_err("Error %d while registering the configfs subsystem %s\n",
+ ret, gpio_sim_config_subsys.su_group.cg_item.ci_namebuf);
+ mutex_destroy(&gpio_sim_config_subsys.su_mutex);
+ platform_driver_unregister(&gpio_sim_driver);
+ return ret;
+ }
+
+ return 0;
+}
+module_init(gpio_sim_init);
+
+static void __exit gpio_sim_exit(void)
+{
+ configfs_unregister_subsystem(&gpio_sim_config_subsys);
+ mutex_destroy(&gpio_sim_config_subsys.su_mutex);
+ platform_driver_unregister(&gpio_sim_driver);
+}
+module_exit(gpio_sim_exit);
+
+MODULE_AUTHOR("Bartosz Golaszewski <brgl@xxxxxxxx");
+MODULE_DESCRIPTION("GPIO Simulator Module");
+MODULE_LICENSE("GPL");
--
2.25.1