diff options
| -rw-r--r-- | drivers/gpio/Kconfig | 2 | ||||
| -rw-r--r-- | drivers/gpio/gpio-aggregator.c | 637 |
2 files changed, 626 insertions, 13 deletions
diff --git a/drivers/gpio/Kconfig b/drivers/gpio/Kconfig index 3244b478d078..688a01ad4d69 100644 --- a/drivers/gpio/Kconfig +++ b/drivers/gpio/Kconfig @@ -1880,6 +1880,8 @@ menu "Virtual GPIO drivers" config GPIO_AGGREGATOR tristate "GPIO Aggregator" + select CONFIGFS_FS + select DEV_SYNC_PROBE help Say yes here to enable the GPIO Aggregator, which provides a way to aggregate existing GPIO lines into a new virtual GPIO chip. diff --git a/drivers/gpio/gpio-aggregator.c b/drivers/gpio/gpio-aggregator.c index 6f933a76b2b9..e5199de2e815 100644 --- a/drivers/gpio/gpio-aggregator.c +++ b/drivers/gpio/gpio-aggregator.c @@ -9,10 +9,13 @@ #include <linux/bitmap.h> #include <linux/bitops.h> +#include <linux/configfs.h> #include <linux/ctype.h> #include <linux/delay.h> #include <linux/idr.h> #include <linux/kernel.h> +#include <linux/list.h> +#include <linux/lockdep.h> #include <linux/mod_devicetable.h> #include <linux/module.h> #include <linux/mutex.h> @@ -27,6 +30,8 @@ #include <linux/gpio/driver.h> #include <linux/gpio/machine.h> +#include "dev-sync-probe.h" + #define AGGREGATOR_MAX_GPIOS 512 /* @@ -34,12 +39,38 @@ */ struct gpio_aggregator { + struct dev_sync_probe_data probe_data; + struct config_group group; struct gpiod_lookup_table *lookups; - struct platform_device *pdev; + struct mutex lock; int id; + + /* List of gpio_aggregator_line. Always added in order */ + struct list_head list_head; + + /* used by legacy sysfs interface only */ + bool init_via_sysfs; char args[]; }; +struct gpio_aggregator_line { + struct config_group group; + struct gpio_aggregator *parent; + struct list_head entry; + + /* Line index within the aggregator device */ + unsigned int idx; + + /* Custom name for the virtual line */ + const char *name; + /* GPIO chip label or line name */ + const char *key; + /* Can be negative to indicate lookup by line name */ + int offset; + + enum gpio_lookup_flags flags; +}; + static DEFINE_MUTEX(gpio_aggregator_lock); /* protects idr */ static DEFINE_IDR(gpio_aggregator_idr); @@ -59,6 +90,8 @@ static int gpio_aggregator_alloc(struct gpio_aggregator **aggr, size_t arg_size) return ret; new->id = ret; + INIT_LIST_HEAD(&new->list_head); + mutex_init(&new->lock); *aggr = no_free_ptr(new); return 0; } @@ -68,6 +101,7 @@ static void gpio_aggregator_free(struct gpio_aggregator *aggr) scoped_guard(mutex, &gpio_aggregator_lock) idr_remove(&gpio_aggregator_idr, aggr->id); + mutex_destroy(&aggr->lock); kfree(aggr); } @@ -90,6 +124,71 @@ static int gpio_aggregator_add_gpio(struct gpio_aggregator *aggr, return 0; } +static bool gpio_aggregator_is_active(struct gpio_aggregator *aggr) +{ + lockdep_assert_held(&aggr->lock); + + return aggr->probe_data.pdev && platform_get_drvdata(aggr->probe_data.pdev); +} + +static size_t gpio_aggregator_count_lines(struct gpio_aggregator *aggr) +{ + lockdep_assert_held(&aggr->lock); + + return list_count_nodes(&aggr->list_head); +} + +static struct gpio_aggregator_line * +gpio_aggregator_line_alloc(struct gpio_aggregator *parent, unsigned int idx, + char *key, int offset) +{ + struct gpio_aggregator_line *line; + + line = kzalloc(sizeof(*line), GFP_KERNEL); + if (!line) + return ERR_PTR(-ENOMEM); + + if (key) { + line->key = kstrdup(key, GFP_KERNEL); + if (!line->key) { + kfree(line); + return ERR_PTR(-ENOMEM); + } + } + + line->flags = GPIO_LOOKUP_FLAGS_DEFAULT; + line->parent = parent; + line->idx = idx; + line->offset = offset; + INIT_LIST_HEAD(&line->entry); + + return line; +} + +static void gpio_aggregator_line_add(struct gpio_aggregator *aggr, + struct gpio_aggregator_line *line) +{ + struct gpio_aggregator_line *tmp; + + lockdep_assert_held(&aggr->lock); + + list_for_each_entry(tmp, &aggr->list_head, entry) { + if (tmp->idx > line->idx) { + list_add_tail(&line->entry, &tmp->entry); + return; + } + } + list_add_tail(&line->entry, &aggr->list_head); +} + +static void gpio_aggregator_line_del(struct gpio_aggregator *aggr, + struct gpio_aggregator_line *line) +{ + lockdep_assert_held(&aggr->lock); + + list_del(&line->entry); +} + /* * GPIO Forwarder @@ -423,6 +522,473 @@ static struct gpiochip_fwd *gpiochip_fwd_create(struct device *dev, return fwd; } +/* + * Configfs interface + */ + +static struct gpio_aggregator * +to_gpio_aggregator(struct config_item *item) +{ + struct config_group *group = to_config_group(item); + + return container_of(group, struct gpio_aggregator, group); +} + +static struct gpio_aggregator_line * +to_gpio_aggregator_line(struct config_item *item) +{ + struct config_group *group = to_config_group(item); + + return container_of(group, struct gpio_aggregator_line, group); +} + +static struct fwnode_handle * +gpio_aggregator_make_device_sw_node(struct gpio_aggregator *aggr) +{ + struct property_entry properties[2]; + struct gpio_aggregator_line *line; + size_t num_lines; + int n = 0; + + memset(properties, 0, sizeof(properties)); + + num_lines = gpio_aggregator_count_lines(aggr); + if (num_lines == 0) + return NULL; + + const char **line_names __free(kfree) = kcalloc( + num_lines, sizeof(*line_names), GFP_KERNEL); + if (!line_names) + return ERR_PTR(-ENOMEM); + + /* The list is always sorted as new elements are inserted in order. */ + list_for_each_entry(line, &aggr->list_head, entry) + line_names[n++] = line->name ?: ""; + + properties[0] = PROPERTY_ENTRY_STRING_ARRAY_LEN( + "gpio-line-names", + line_names, num_lines); + + return fwnode_create_software_node(properties, NULL); +} + +static int gpio_aggregator_activate(struct gpio_aggregator *aggr) +{ + struct platform_device_info pdevinfo; + struct gpio_aggregator_line *line; + struct fwnode_handle *swnode; + unsigned int n = 0; + int ret = 0; + + if (gpio_aggregator_count_lines(aggr) == 0) + return -EINVAL; + + aggr->lookups = kzalloc(struct_size(aggr->lookups, table, 1), + GFP_KERNEL); + if (!aggr->lookups) + return -ENOMEM; + + swnode = gpio_aggregator_make_device_sw_node(aggr); + if (IS_ERR(swnode)) + goto err_remove_lookups; + + memset(&pdevinfo, 0, sizeof(pdevinfo)); + pdevinfo.name = DRV_NAME; + pdevinfo.id = aggr->id; + pdevinfo.fwnode = swnode; + + /* The list is always sorted as new elements are inserted in order. */ + list_for_each_entry(line, &aggr->list_head, entry) { + /* + * - Either GPIO chip label or line name must be configured + * (i.e. line->key must be non-NULL) + * - Line directories must be named with sequential numeric + * suffixes starting from 0. (i.e. ./line0, ./line1, ...) + */ + if (!line->key || line->idx != n) { + ret = -EINVAL; + goto err_remove_swnode; + } + + if (line->offset < 0) + ret = gpio_aggregator_add_gpio(aggr, line->key, + U16_MAX, &n); + else + ret = gpio_aggregator_add_gpio(aggr, line->key, + line->offset, &n); + if (ret) + goto err_remove_swnode; + } + + aggr->lookups->dev_id = kasprintf(GFP_KERNEL, "%s.%d", DRV_NAME, aggr->id); + if (!aggr->lookups->dev_id) { + ret = -ENOMEM; + goto err_remove_swnode; + } + + gpiod_add_lookup_table(aggr->lookups); + + ret = dev_sync_probe_register(&aggr->probe_data, &pdevinfo); + if (ret) + goto err_remove_lookup_table; + + return 0; + +err_remove_lookup_table: + kfree(aggr->lookups->dev_id); + gpiod_remove_lookup_table(aggr->lookups); +err_remove_swnode: + fwnode_remove_software_node(swnode); +err_remove_lookups: + kfree(aggr->lookups); + + return ret; +} + +static void gpio_aggregator_deactivate(struct gpio_aggregator *aggr) +{ + dev_sync_probe_unregister(&aggr->probe_data); + gpiod_remove_lookup_table(aggr->lookups); + kfree(aggr->lookups->dev_id); + kfree(aggr->lookups); +} + +static void gpio_aggregator_lockup_configfs(struct gpio_aggregator *aggr, + bool lock) +{ + struct configfs_subsystem *subsys = aggr->group.cg_subsys; + struct gpio_aggregator_line *line; + + /* + * The device only needs to depend on leaf lines. This is + * sufficient to lock up all the configfs entries that the + * instantiated, alive device depends on. + */ + list_for_each_entry(line, &aggr->list_head, entry) { + if (lock) + configfs_depend_item_unlocked( + subsys, &line->group.cg_item); + else + configfs_undepend_item_unlocked( + &line->group.cg_item); + } +} + +static ssize_t +gpio_aggregator_line_key_show(struct config_item *item, char *page) +{ + struct gpio_aggregator_line *line = to_gpio_aggregator_line(item); + struct gpio_aggregator *aggr = line->parent; + + guard(mutex)(&aggr->lock); + + return sysfs_emit(page, "%s\n", line->key ?: ""); +} + +static ssize_t +gpio_aggregator_line_key_store(struct config_item *item, const char *page, + size_t count) +{ + struct gpio_aggregator_line *line = to_gpio_aggregator_line(item); + struct gpio_aggregator *aggr = line->parent; + + char *key __free(kfree) = kstrndup(skip_spaces(page), count, + GFP_KERNEL); + if (!key) + return -ENOMEM; + + strim(key); + + guard(mutex)(&aggr->lock); + + if (gpio_aggregator_is_active(aggr)) + return -EBUSY; + + kfree(line->key); + line->key = no_free_ptr(key); + + return count; +} +CONFIGFS_ATTR(gpio_aggregator_line_, key); + +static ssize_t +gpio_aggregator_line_name_show(struct config_item *item, char *page) +{ + struct gpio_aggregator_line *line = to_gpio_aggregator_line(item); + struct gpio_aggregator *aggr = line->parent; + + guard(mutex)(&aggr->lock); + + return sysfs_emit(page, "%s\n", line->name ?: ""); +} + +static ssize_t +gpio_aggregator_line_name_store(struct config_item *item, const char *page, + size_t count) +{ + struct gpio_aggregator_line *line = to_gpio_aggregator_line(item); + struct gpio_aggregator *aggr = line->parent; + + char *name __free(kfree) = kstrndup(skip_spaces(page), count, + GFP_KERNEL); + if (!name) + return -ENOMEM; + + strim(name); + + guard(mutex)(&aggr->lock); + + if (gpio_aggregator_is_active(aggr)) + return -EBUSY; + + kfree(line->name); + line->name = no_free_ptr(name); + + return count; +} +CONFIGFS_ATTR(gpio_aggregator_line_, name); + +static ssize_t +gpio_aggregator_line_offset_show(struct config_item *item, char *page) +{ + struct gpio_aggregator_line *line = to_gpio_aggregator_line(item); + struct gpio_aggregator *aggr = line->parent; + + guard(mutex)(&aggr->lock); + + return sysfs_emit(page, "%d\n", line->offset); +} + +static ssize_t +gpio_aggregator_line_offset_store(struct config_item *item, const char *page, + size_t count) +{ + struct gpio_aggregator_line *line = to_gpio_aggregator_line(item); + struct gpio_aggregator *aggr = line->parent; + int offset, ret; + + ret = kstrtoint(page, 0, &offset); + if (ret) + return ret; + + /* + * When offset == -1, 'key' represents a line name to lookup. + * When 0 <= offset < 65535, 'key' represents the label of the chip with + * the 'offset' value representing the line within that chip. + * + * GPIOLIB uses the U16_MAX value to indicate lookup by line name so + * the greatest offset we can accept is (U16_MAX - 1). + */ + if (offset > (U16_MAX - 1) || offset < -1) + return -EINVAL; + + guard(mutex)(&aggr->lock); + + if (gpio_aggregator_is_active(aggr)) + return -EBUSY; + + line->offset = offset; + + return count; +} +CONFIGFS_ATTR(gpio_aggregator_line_, offset); + +static struct configfs_attribute *gpio_aggregator_line_attrs[] = { + &gpio_aggregator_line_attr_key, + &gpio_aggregator_line_attr_name, + &gpio_aggregator_line_attr_offset, + NULL +}; + +static ssize_t +gpio_aggregator_device_dev_name_show(struct config_item *item, char *page) +{ + struct gpio_aggregator *aggr = to_gpio_aggregator(item); + struct platform_device *pdev; + + guard(mutex)(&aggr->lock); + + pdev = aggr->probe_data.pdev; + if (pdev) + return sysfs_emit(page, "%s\n", dev_name(&pdev->dev)); + + return sysfs_emit(page, "%s.%d\n", DRV_NAME, aggr->id); +} +CONFIGFS_ATTR_RO(gpio_aggregator_device_, dev_name); + +static ssize_t +gpio_aggregator_device_live_show(struct config_item *item, char *page) +{ + struct gpio_aggregator *aggr = to_gpio_aggregator(item); + + guard(mutex)(&aggr->lock); + + return sysfs_emit(page, "%c\n", + gpio_aggregator_is_active(aggr) ? '1' : '0'); +} + +static ssize_t +gpio_aggregator_device_live_store(struct config_item *item, const char *page, + size_t count) +{ + struct gpio_aggregator *aggr = to_gpio_aggregator(item); + int ret = 0; + bool live; + + ret = kstrtobool(page, &live); + if (ret) + return ret; + + if (!try_module_get(THIS_MODULE)) + return -ENOENT; + + if (live) + gpio_aggregator_lockup_configfs(aggr, true); + + scoped_guard(mutex, &aggr->lock) { + if (live == gpio_aggregator_is_active(aggr)) + ret = -EPERM; + else if (live) + ret = gpio_aggregator_activate(aggr); + else + gpio_aggregator_deactivate(aggr); + } + + /* + * Undepend is required only if device disablement (live == 0) + * succeeds or if device enablement (live == 1) fails. + */ + if (live == !!ret) + gpio_aggregator_lockup_configfs(aggr, false); + + module_put(THIS_MODULE); + + return ret ?: count; +} +CONFIGFS_ATTR(gpio_aggregator_device_, live); + +static struct configfs_attribute *gpio_aggregator_device_attrs[] = { + &gpio_aggregator_device_attr_dev_name, + &gpio_aggregator_device_attr_live, + NULL +}; + +static void +gpio_aggregator_line_release(struct config_item *item) +{ + struct gpio_aggregator_line *line = to_gpio_aggregator_line(item); + struct gpio_aggregator *aggr = line->parent; + + guard(mutex)(&aggr->lock); + + gpio_aggregator_line_del(aggr, line); + kfree(line->key); + kfree(line->name); + kfree(line); +} + +static struct configfs_item_operations gpio_aggregator_line_item_ops = { + .release = gpio_aggregator_line_release, +}; + +static const struct config_item_type gpio_aggregator_line_type = { + .ct_item_ops = &gpio_aggregator_line_item_ops, + .ct_attrs = gpio_aggregator_line_attrs, + .ct_owner = THIS_MODULE, +}; + +static void gpio_aggregator_device_release(struct config_item *item) +{ + struct gpio_aggregator *aggr = to_gpio_aggregator(item); + + /* + * If the aggregator is active, this code wouldn't be reached, + * so calling gpio_aggregator_deactivate() is always unnecessary. + */ + gpio_aggregator_free(aggr); +} + +static struct configfs_item_operations gpio_aggregator_device_item_ops = { + .release = gpio_aggregator_device_release, +}; + +static struct config_group * +gpio_aggregator_device_make_group(struct config_group *group, const char *name) +{ + struct gpio_aggregator *aggr = to_gpio_aggregator(&group->cg_item); + struct gpio_aggregator_line *line; + unsigned int idx; + int ret, nchar; + + ret = sscanf(name, "line%u%n", &idx, &nchar); + if (ret != 1 || nchar != strlen(name)) + return ERR_PTR(-EINVAL); + + guard(mutex)(&aggr->lock); + + if (gpio_aggregator_is_active(aggr)) + return ERR_PTR(-EBUSY); + + list_for_each_entry(line, &aggr->list_head, entry) + if (line->idx == idx) + return ERR_PTR(-EINVAL); + + line = gpio_aggregator_line_alloc(aggr, idx, NULL, -1); + if (!line) + return ERR_PTR(-ENOMEM); + + config_group_init_type_name(&line->group, name, &gpio_aggregator_line_type); + + gpio_aggregator_line_add(aggr, line); + + return &line->group; +} + +static struct configfs_group_operations gpio_aggregator_device_group_ops = { + .make_group = gpio_aggregator_device_make_group, +}; + +static const struct config_item_type gpio_aggregator_device_type = { + .ct_group_ops = &gpio_aggregator_device_group_ops, + .ct_item_ops = &gpio_aggregator_device_item_ops, + .ct_attrs = gpio_aggregator_device_attrs, + .ct_owner = THIS_MODULE, +}; + +static struct config_group * +gpio_aggregator_make_group(struct config_group *group, const char *name) +{ + struct gpio_aggregator *aggr; + int ret; + + /* arg space is unneeded */ + ret = gpio_aggregator_alloc(&aggr, 0); + if (ret) + return ERR_PTR(ret); + + config_group_init_type_name(&aggr->group, name, &gpio_aggregator_device_type); + dev_sync_probe_init(&aggr->probe_data); + + return &aggr->group; +} + +static struct configfs_group_operations gpio_aggregator_group_ops = { + .make_group = gpio_aggregator_make_group, +}; + +static const struct config_item_type gpio_aggregator_type = { + .ct_group_ops = &gpio_aggregator_group_ops, + .ct_owner = THIS_MODULE, +}; + +static struct configfs_subsystem gpio_aggregator_subsys = { + .su_group = { + .cg_item = { + .ci_namebuf = DRV_NAME, + .ci_type = &gpio_aggregator_type, + }, + }, +}; /* * Sysfs interface @@ -495,6 +1061,7 @@ static ssize_t gpio_aggregator_new_device_store(struct device_driver *driver, memcpy(aggr->args, buf, count + 1); + aggr->init_via_sysfs = true; aggr->lookups = kzalloc(struct_size(aggr->lookups, table, 1), GFP_KERNEL); if (!aggr->lookups) { @@ -520,7 +1087,7 @@ static ssize_t gpio_aggregator_new_device_store(struct device_driver *driver, goto remove_table; } - aggr->pdev = pdev; + aggr->probe_data.pdev = pdev; module_put(THIS_MODULE); return count; @@ -542,10 +1109,7 @@ static struct driver_attribute driver_attr_gpio_aggregator_new_device = static void gpio_aggregator_destroy(struct gpio_aggregator *aggr) { - platform_device_unregister(aggr->pdev); - gpiod_remove_lookup_table(aggr->lookups); - kfree(aggr->lookups->dev_id); - kfree(aggr->lookups); + gpio_aggregator_deactivate(aggr); kfree(aggr); } @@ -567,12 +1131,19 @@ static ssize_t gpio_aggregator_delete_device_store(struct device_driver *driver, return -ENOENT; mutex_lock(&gpio_aggregator_lock); - aggr = idr_remove(&gpio_aggregator_idr, id); - mutex_unlock(&gpio_aggregator_lock); - if (!aggr) { + aggr = idr_find(&gpio_aggregator_idr, id); + /* + * For simplicity, devices created via configfs cannot be deleted + * via sysfs. + */ + if (aggr && aggr->init_via_sysfs) + idr_remove(&gpio_aggregator_idr, id); + else { + mutex_unlock(&gpio_aggregator_lock); module_put(THIS_MODULE); return -ENOENT; } + mutex_unlock(&gpio_aggregator_lock); gpio_aggregator_destroy(aggr); module_put(THIS_MODULE); @@ -589,7 +1160,6 @@ static struct attribute *gpio_aggregator_attrs[] = { }; ATTRIBUTE_GROUPS(gpio_aggregator); - /* * GPIO Aggregator platform device */ @@ -649,21 +1219,61 @@ static struct platform_driver gpio_aggregator_driver = { static int __exit gpio_aggregator_idr_remove(int id, void *p, void *data) { + /* + * There should be no aggregator created via configfs, as their + * presence would prevent module unloading. + */ gpio_aggregator_destroy(p); return 0; } static void __exit gpio_aggregator_remove_all(void) { - mutex_lock(&gpio_aggregator_lock); + /* + * Configfs callbacks acquire gpio_aggregator_lock when accessing + * gpio_aggregator_idr, so to prevent lock inversion deadlock, we + * cannot protect idr_for_each invocation here with + * gpio_aggregator_lock, as gpio_aggregator_idr_remove() accesses + * configfs groups. Fortunately, the new_device/delete_device path + * and the module unload path are mutually exclusive, thanks to an + * explicit try_module_get inside of those driver attr handlers. + * Also, when we reach here, no configfs entries present or being + * created. Therefore, no need to protect with gpio_aggregator_lock + * below. + */ idr_for_each(&gpio_aggregator_idr, gpio_aggregator_idr_remove, NULL); idr_destroy(&gpio_aggregator_idr); - mutex_unlock(&gpio_aggregator_lock); } static int __init gpio_aggregator_init(void) { - return platform_driver_register(&gpio_aggregator_driver); + int ret = 0; + + config_group_init(&gpio_aggregator_subsys.su_group); + mutex_init(&gpio_aggregator_subsys.su_mutex); + ret = configfs_register_subsystem(&gpio_aggregator_subsys); + if (ret) { + pr_err("Failed to register the '%s' configfs subsystem: %d\n", + gpio_aggregator_subsys.su_group.cg_item.ci_namebuf, ret); + mutex_destroy(&gpio_aggregator_subsys.su_mutex); + return ret; + } + + /* + * CAVEAT: This must occur after configfs registration. Otherwise, + * a race condition could arise: driver attribute groups might be + * exposed and accessed by users before configfs registration + * completes. new_device_store() does not expect a partially + * initialized configfs state. + */ + ret = platform_driver_register(&gpio_aggregator_driver); + if (ret) { + pr_err("Failed to register the platform driver: %d\n", ret); + mutex_destroy(&gpio_aggregator_subsys.su_mutex); + configfs_unregister_subsystem(&gpio_aggregator_subsys); + } + + return ret; } module_init(gpio_aggregator_init); @@ -671,6 +1281,7 @@ static void __exit gpio_aggregator_exit(void) { gpio_aggregator_remove_all(); platform_driver_unregister(&gpio_aggregator_driver); + configfs_unregister_subsystem(&gpio_aggregator_subsys); } module_exit(gpio_aggregator_exit); |