diff --git a/drivers/gpio/Kconfig b/drivers/gpio/Kconfig index 7ee3afbc2b05..b8b6537290b0 100644 --- a/drivers/gpio/Kconfig +++ b/drivers/gpio/Kconfig @@ -6,6 +6,9 @@ config GPIOLIB_LEGACY def_bool y +config HAVE_SHARED_GPIOS + bool + menuconfig GPIOLIB bool "GPIO Support" help @@ -50,6 +53,11 @@ config OF_GPIO_MM_GPIOCHIP this symbol, but new drivers should use the generic gpio-regmap infrastructure instead. +config GPIO_SHARED + def_bool y + depends on HAVE_SHARED_GPIOS || COMPILE_TEST + select AUXILIARY_BUS + config DEBUG_GPIO bool "Debug GPIO calls" depends on DEBUG_KERNEL @@ -2017,6 +2025,15 @@ config GPIO_SIM This enables the GPIO simulator - a configfs-based GPIO testing driver. +config GPIO_SHARED_PROXY + tristate "Proxy driver for non-exclusive GPIOs" + default m + depends on GPIO_SHARED || COMPILE_TEST + select AUXILIARY_BUS + help + This enables the GPIO shared proxy driver - an abstraction layer + for GPIO pins that are shared by multiple devices. + endmenu menu "GPIO Debugging utilities" diff --git a/drivers/gpio/Makefile b/drivers/gpio/Makefile index ec296fa14bfd..d0020bc70b84 100644 --- a/drivers/gpio/Makefile +++ b/drivers/gpio/Makefile @@ -12,6 +12,7 @@ obj-$(CONFIG_GPIO_SYSFS) += gpiolib-sysfs.o obj-$(CONFIG_GPIO_ACPI) += gpiolib-acpi.o gpiolib-acpi-y := gpiolib-acpi-core.o gpiolib-acpi-quirks.o obj-$(CONFIG_GPIOLIB) += gpiolib-swnode.o +obj-$(CONFIG_GPIO_SHARED) += gpiolib-shared.o # Device drivers. Generally keep list sorted alphabetically obj-$(CONFIG_GPIO_REGMAP) += gpio-regmap.o @@ -159,6 +160,7 @@ obj-$(CONFIG_ARCH_SA1100) += gpio-sa1100.o 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_SHARED_PROXY) += gpio-shared-proxy.o obj-$(CONFIG_GPIO_SIFIVE) += gpio-sifive.o obj-$(CONFIG_GPIO_SIM) += gpio-sim.o obj-$(CONFIG_GPIO_SIOX) += gpio-siox.o diff --git a/drivers/gpio/gpio-shared-proxy.c b/drivers/gpio/gpio-shared-proxy.c new file mode 100644 index 000000000000..3ef2c40ed152 --- /dev/null +++ b/drivers/gpio/gpio-shared-proxy.c @@ -0,0 +1,333 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * Copyright (C) 2025 Linaro Ltd. + */ + +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include + +#include "gpiolib-shared.h" + +struct gpio_shared_proxy_data { + struct gpio_chip gc; + struct gpio_shared_desc *shared_desc; + struct device *dev; + bool voted_high; +}; + +static int +gpio_shared_proxy_set_unlocked(struct gpio_shared_proxy_data *proxy, + int (*set_func)(struct gpio_desc *desc, int value), + int value) +{ + struct gpio_shared_desc *shared_desc = proxy->shared_desc; + struct gpio_desc *desc = shared_desc->desc; + int ret = 0; + + gpio_shared_lockdep_assert(shared_desc); + + if (value) { + /* User wants to set value to high. */ + if (proxy->voted_high) + /* Already voted for high, nothing to do. */ + goto out; + + /* Haven't voted for high yet. */ + if (!shared_desc->highcnt) { + /* + * Current value is low, need to actually set value + * to high. + */ + ret = set_func(desc, 1); + if (ret) + goto out; + } + + shared_desc->highcnt++; + proxy->voted_high = true; + + goto out; + } + + /* Desired value is low. */ + if (!proxy->voted_high) + /* We didn't vote for high, nothing to do. */ + goto out; + + /* We previously voted for high. */ + if (shared_desc->highcnt == 1) { + /* This is the last remaining vote for high, set value to low. */ + ret = set_func(desc, 0); + if (ret) + goto out; + } + + shared_desc->highcnt--; + proxy->voted_high = false; + +out: + if (shared_desc->highcnt) + dev_dbg(proxy->dev, + "Voted for value '%s', effective value is 'high', number of votes for 'high': %u\n", + str_high_low(value), shared_desc->highcnt); + else + dev_dbg(proxy->dev, "Voted for value 'low', effective value is 'low'\n"); + + return ret; +} + +static int gpio_shared_proxy_request(struct gpio_chip *gc, unsigned int offset) +{ + struct gpio_shared_proxy_data *proxy = gpiochip_get_data(gc); + struct gpio_shared_desc *shared_desc = proxy->shared_desc; + + guard(gpio_shared_desc_lock)(shared_desc); + + proxy->shared_desc->usecnt++; + + dev_dbg(proxy->dev, "Shared GPIO requested, number of users: %u\n", + proxy->shared_desc->usecnt); + + return 0; +} + +static void gpio_shared_proxy_free(struct gpio_chip *gc, unsigned int offset) +{ + struct gpio_shared_proxy_data *proxy = gpiochip_get_data(gc); + struct gpio_shared_desc *shared_desc = proxy->shared_desc; + + guard(gpio_shared_desc_lock)(shared_desc); + + proxy->shared_desc->usecnt--; + + dev_dbg(proxy->dev, "Shared GPIO freed, number of users: %u\n", + proxy->shared_desc->usecnt); +} + +static int gpio_shared_proxy_set_config(struct gpio_chip *gc, + unsigned int offset, unsigned long cfg) +{ + struct gpio_shared_proxy_data *proxy = gpiochip_get_data(gc); + struct gpio_shared_desc *shared_desc = proxy->shared_desc; + struct gpio_desc *desc = shared_desc->desc; + int ret; + + guard(gpio_shared_desc_lock)(shared_desc); + + if (shared_desc->usecnt > 1) { + if (shared_desc->cfg != cfg) { + dev_dbg(proxy->dev, + "Shared GPIO's configuration already set, accepting changes but users may conflict!!\n"); + } else { + dev_dbg(proxy->dev, "Equal config requested, nothing to do\n"); + return 0; + } + } + + ret = gpiod_set_config(desc, cfg); + if (ret && ret != -ENOTSUPP) + return ret; + + shared_desc->cfg = cfg; + return 0; +} + +static int gpio_shared_proxy_direction_input(struct gpio_chip *gc, + unsigned int offset) +{ + struct gpio_shared_proxy_data *proxy = gpiochip_get_data(gc); + struct gpio_shared_desc *shared_desc = proxy->shared_desc; + struct gpio_desc *desc = shared_desc->desc; + int dir; + + guard(gpio_shared_desc_lock)(shared_desc); + + if (shared_desc->usecnt == 1) { + dev_dbg(proxy->dev, + "Only one user of this shared GPIO, allowing to set direction to input\n"); + + return gpiod_direction_input(desc); + } + + dir = gpiod_get_direction(desc); + if (dir < 0) + return dir; + + if (dir == GPIO_LINE_DIRECTION_OUT) { + dev_dbg(proxy->dev, + "Shared GPIO's direction already set to output, refusing to change\n"); + return -EPERM; + } + + return 0; +} + +static int gpio_shared_proxy_direction_output(struct gpio_chip *gc, + unsigned int offset, int value) +{ + struct gpio_shared_proxy_data *proxy = gpiochip_get_data(gc); + struct gpio_shared_desc *shared_desc = proxy->shared_desc; + struct gpio_desc *desc = shared_desc->desc; + int ret, dir; + + guard(gpio_shared_desc_lock)(shared_desc); + + if (shared_desc->usecnt == 1) { + dev_dbg(proxy->dev, + "Only one user of this shared GPIO, allowing to set direction to output with value '%s'\n", + str_high_low(value)); + + ret = gpiod_direction_output(desc, value); + if (ret) + return ret; + + if (value) { + proxy->voted_high = true; + shared_desc->highcnt = 1; + } else { + proxy->voted_high = false; + shared_desc->highcnt = 0; + } + + return 0; + } + + dir = gpiod_get_direction(desc); + if (dir < 0) + return dir; + + if (dir == GPIO_LINE_DIRECTION_IN) { + dev_dbg(proxy->dev, + "Shared GPIO's direction already set to input, refusing to change\n"); + return -EPERM; + } + + return gpio_shared_proxy_set_unlocked(proxy, gpiod_direction_output, value); +} + +static int gpio_shared_proxy_get(struct gpio_chip *gc, unsigned int offset) +{ + struct gpio_shared_proxy_data *proxy = gpiochip_get_data(gc); + + return gpiod_get_value(proxy->shared_desc->desc); +} + +static int gpio_shared_proxy_get_cansleep(struct gpio_chip *gc, + unsigned int offset) +{ + struct gpio_shared_proxy_data *proxy = gpiochip_get_data(gc); + + return gpiod_get_value_cansleep(proxy->shared_desc->desc); +} + +static int gpio_shared_proxy_do_set(struct gpio_shared_proxy_data *proxy, + int (*set_func)(struct gpio_desc *desc, int value), + int value) +{ + guard(gpio_shared_desc_lock)(proxy->shared_desc); + + return gpio_shared_proxy_set_unlocked(proxy, set_func, value); +} + +static int gpio_shared_proxy_set(struct gpio_chip *gc, unsigned int offset, + int value) +{ + struct gpio_shared_proxy_data *proxy = gpiochip_get_data(gc); + + return gpio_shared_proxy_do_set(proxy, gpiod_set_value, value); +} + +static int gpio_shared_proxy_set_cansleep(struct gpio_chip *gc, + unsigned int offset, int value) +{ + struct gpio_shared_proxy_data *proxy = gpiochip_get_data(gc); + + return gpio_shared_proxy_do_set(proxy, gpiod_set_value_cansleep, value); +} + +static int gpio_shared_proxy_get_direction(struct gpio_chip *gc, + unsigned int offset) +{ + struct gpio_shared_proxy_data *proxy = gpiochip_get_data(gc); + + return gpiod_get_direction(proxy->shared_desc->desc); +} + +static int gpio_shared_proxy_to_irq(struct gpio_chip *gc, unsigned int offset) +{ + struct gpio_shared_proxy_data *proxy = gpiochip_get_data(gc); + + return gpiod_to_irq(proxy->shared_desc->desc); +} + +static int gpio_shared_proxy_probe(struct auxiliary_device *adev, + const struct auxiliary_device_id *id) +{ + struct gpio_shared_proxy_data *proxy; + struct gpio_shared_desc *shared_desc; + struct device *dev = &adev->dev; + struct gpio_chip *gc; + + shared_desc = devm_gpiod_shared_get(dev); + if (IS_ERR(shared_desc)) + return PTR_ERR(shared_desc); + + proxy = devm_kzalloc(dev, sizeof(*proxy), GFP_KERNEL); + if (!proxy) + return -ENOMEM; + + proxy->shared_desc = shared_desc; + proxy->dev = dev; + + gc = &proxy->gc; + gc->base = -1; + gc->ngpio = 1; + gc->label = dev_name(dev); + gc->parent = dev; + gc->owner = THIS_MODULE; + gc->can_sleep = shared_desc->can_sleep; + + gc->request = gpio_shared_proxy_request; + gc->free = gpio_shared_proxy_free; + gc->set_config = gpio_shared_proxy_set_config; + gc->direction_input = gpio_shared_proxy_direction_input; + gc->direction_output = gpio_shared_proxy_direction_output; + if (gc->can_sleep) { + gc->set = gpio_shared_proxy_set_cansleep; + gc->get = gpio_shared_proxy_get_cansleep; + } else { + gc->set = gpio_shared_proxy_set; + gc->get = gpio_shared_proxy_get; + } + gc->get_direction = gpio_shared_proxy_get_direction; + gc->to_irq = gpio_shared_proxy_to_irq; + + return devm_gpiochip_add_data(dev, &proxy->gc, proxy); +} + +static const struct auxiliary_device_id gpio_shared_proxy_id_table[] = { + { .name = "gpiolib_shared.proxy" }, + {}, +}; +MODULE_DEVICE_TABLE(auxiliary, gpio_shared_proxy_id_table); + +static struct auxiliary_driver gpio_shared_proxy_driver = { + .driver = { + .name = "gpio-shared-proxy", + }, + .probe = gpio_shared_proxy_probe, + .id_table = gpio_shared_proxy_id_table, +}; +module_auxiliary_driver(gpio_shared_proxy_driver); + +MODULE_AUTHOR("Bartosz Golaszewski "); +MODULE_DESCRIPTION("Shared GPIO mux driver."); +MODULE_LICENSE("GPL"); diff --git a/drivers/gpio/gpiolib-shared.c b/drivers/gpio/gpiolib-shared.c new file mode 100644 index 000000000000..fa1d16635ea7 --- /dev/null +++ b/drivers/gpio/gpiolib-shared.c @@ -0,0 +1,558 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * Copyright (C) 2025 Linaro Ltd. + */ + +#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt + +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include + +#include "gpiolib.h" +#include "gpiolib-shared.h" + +/* Represents a single reference to a GPIO pin. */ +struct gpio_shared_ref { + struct list_head list; + /* Firmware node associated with this GPIO's consumer. */ + struct fwnode_handle *fwnode; + /* GPIO flags this consumer uses for the request. */ + enum gpiod_flags flags; + char *con_id; + int dev_id; + struct auxiliary_device adev; + struct gpiod_lookup_table *lookup; +}; + +/* Represents a single GPIO pin. */ +struct gpio_shared_entry { + struct list_head list; + /* Firmware node associated with the GPIO controller. */ + struct fwnode_handle *fwnode; + /* Hardware offset of the GPIO within its chip. */ + unsigned int offset; + /* Index in the property value array. */ + size_t index; + struct gpio_shared_desc *shared_desc; + struct kref ref; + struct list_head refs; +}; + +static LIST_HEAD(gpio_shared_list); +static DEFINE_MUTEX(gpio_shared_lock); +static DEFINE_IDA(gpio_shared_ida); + +static struct gpio_shared_entry * +gpio_shared_find_entry(struct fwnode_handle *controller_node, + unsigned int offset) +{ + struct gpio_shared_entry *entry; + + list_for_each_entry(entry, &gpio_shared_list, list) { + if (entry->fwnode == controller_node && entry->offset == offset) + return entry; + } + + return NULL; +} + +#if IS_ENABLED(CONFIG_OF) +static int gpio_shared_of_traverse(struct device_node *curr) +{ + struct gpio_shared_entry *entry; + size_t con_id_len, suffix_len; + struct fwnode_handle *fwnode; + struct of_phandle_args args; + struct property *prop; + unsigned int offset; + const char *suffix; + int ret, count, i; + + for_each_property_of_node(curr, prop) { + /* + * The standard name for a GPIO property is "foo-gpios" + * or "foo-gpio". Some bindings also use "gpios" or "gpio". + * There are some legacy device-trees which have a different + * naming convention and for which we have rename quirks in + * place in gpiolib-of.c. I don't think any of them require + * support for shared GPIOs so for now let's just ignore + * them. We can always just export the quirk list and + * iterate over it here. + */ + if (!strends(prop->name, "-gpios") && + !strends(prop->name, "-gpio") && + strcmp(prop->name, "gpios") != 0 && + strcmp(prop->name, "gpio") != 0) + continue; + + count = of_count_phandle_with_args(curr, prop->name, + "#gpio-cells"); + if (count <= 0) + continue; + + for (i = 0; i < count; i++) { + struct device_node *np __free(device_node) = NULL; + + ret = of_parse_phandle_with_args(curr, prop->name, + "#gpio-cells", i, + &args); + if (ret) + continue; + + np = args.np; + + if (!of_property_present(np, "gpio-controller")) + continue; + + /* + * We support 1, 2 and 3 cell GPIO bindings in the + * kernel currently. There's only one old MIPS dts that + * has a one-cell binding but there's no associated + * consumer so it may as well be an error. There don't + * seem to be any 3-cell users of non-exclusive GPIOs, + * so we can skip this as well. Let's occupy ourselves + * with the predominant 2-cell binding with the first + * cell indicating the hardware offset of the GPIO and + * the second defining the GPIO flags of the request. + */ + if (args.args_count != 2) + continue; + + fwnode = of_fwnode_handle(args.np); + offset = args.args[0]; + + entry = gpio_shared_find_entry(fwnode, offset); + if (!entry) { + entry = kzalloc(sizeof(*entry), GFP_KERNEL); + if (!entry) + return -ENOMEM; + + entry->fwnode = fwnode_handle_get(fwnode); + entry->offset = offset; + entry->index = count; + INIT_LIST_HEAD(&entry->refs); + + list_add_tail(&entry->list, &gpio_shared_list); + } + + struct gpio_shared_ref *ref __free(kfree) = + kzalloc(sizeof(*ref), GFP_KERNEL); + if (!ref) + return -ENOMEM; + + ref->fwnode = fwnode_handle_get(of_fwnode_handle(curr)); + ref->flags = args.args[1]; + + if (strends(prop->name, "gpios")) + suffix = "-gpios"; + else if (strends(prop->name, "gpio")) + suffix = "-gpio"; + else + suffix = NULL; + if (!suffix) + continue; + + /* We only set con_id if there's actually one. */ + if (strcmp(prop->name, "gpios") && strcmp(prop->name, "gpio")) { + ref->con_id = kstrdup(prop->name, GFP_KERNEL); + if (!ref->con_id) + return -ENOMEM; + + con_id_len = strlen(ref->con_id); + suffix_len = strlen(suffix); + + ref->con_id[con_id_len - suffix_len] = '\0'; + } + + ref->dev_id = ida_alloc(&gpio_shared_ida, GFP_KERNEL); + if (ref->dev_id < 0) { + kfree(ref->con_id); + return -ENOMEM; + } + + if (!list_empty(&entry->refs)) + pr_debug("GPIO %u at %s is shared by multiple firmware nodes\n", + entry->offset, fwnode_get_name(entry->fwnode)); + + list_add_tail(&no_free_ptr(ref)->list, &entry->refs); + } + } + + for_each_child_of_node_scoped(curr, child) { + ret = gpio_shared_of_traverse(child); + if (ret) + return ret; + } + + return 0; +} + +static int gpio_shared_of_scan(void) +{ + return gpio_shared_of_traverse(of_root); +} +#else +static int gpio_shared_of_scan(void) +{ + return 0; +} +#endif /* CONFIG_OF */ + +static void gpio_shared_adev_release(struct device *dev) +{ + +} + +static int gpio_shared_make_adev(struct gpio_device *gdev, + struct gpio_shared_ref *ref) +{ + struct auxiliary_device *adev = &ref->adev; + int ret; + + lockdep_assert_held(&gpio_shared_lock); + + memset(adev, 0, sizeof(*adev)); + + adev->id = ref->dev_id; + adev->name = "proxy"; + adev->dev.parent = gdev->dev.parent; + adev->dev.release = gpio_shared_adev_release; + + ret = auxiliary_device_init(adev); + if (ret) + return ret; + + ret = auxiliary_device_add(adev); + if (ret) { + auxiliary_device_uninit(adev); + return ret; + } + + pr_debug("Created an auxiliary GPIO proxy %s for GPIO device %s\n", + dev_name(&adev->dev), gpio_device_get_label(gdev)); + + return 0; +} + +int gpio_shared_add_proxy_lookup(struct device *consumer, unsigned long lflags) +{ + const char *dev_id = dev_name(consumer); + struct gpio_shared_entry *entry; + struct gpio_shared_ref *ref; + + struct gpiod_lookup_table *lookup __free(kfree) = + kzalloc(struct_size(lookup, table, 2), GFP_KERNEL); + if (!lookup) + return -ENOMEM; + + guard(mutex)(&gpio_shared_lock); + + list_for_each_entry(entry, &gpio_shared_list, list) { + list_for_each_entry(ref, &entry->refs, list) { + if (!device_match_fwnode(consumer, ref->fwnode)) + continue; + + /* We've already done that on a previous request. */ + if (ref->lookup) + return 0; + + char *key __free(kfree) = + kasprintf(GFP_KERNEL, + KBUILD_MODNAME ".proxy.%u", + ref->adev.id); + if (!key) + return -ENOMEM; + + pr_debug("Adding machine lookup entry for a shared GPIO for consumer %s, with key '%s' and con_id '%s'\n", + dev_id, key, ref->con_id ?: "none"); + + lookup->dev_id = dev_id; + lookup->table[0] = GPIO_LOOKUP(no_free_ptr(key), 0, + ref->con_id, lflags); + + gpiod_add_lookup_table(no_free_ptr(lookup)); + + return 0; + } + } + + /* We warn here because this can only happen if the programmer borked. */ + WARN_ON(1); + return -ENOENT; +} + +static void gpio_shared_remove_adev(struct auxiliary_device *adev) +{ + lockdep_assert_held(&gpio_shared_lock); + + auxiliary_device_uninit(adev); + auxiliary_device_delete(adev); +} + +int gpio_device_setup_shared(struct gpio_device *gdev) +{ + struct gpio_shared_entry *entry; + struct gpio_shared_ref *ref; + unsigned long *flags; + int ret; + + guard(mutex)(&gpio_shared_lock); + + list_for_each_entry(entry, &gpio_shared_list, list) { + list_for_each_entry(ref, &entry->refs, list) { + if (gdev->dev.parent == &ref->adev.dev) { + /* + * This is a shared GPIO proxy. Mark its + * descriptor as such and return here. + */ + __set_bit(GPIOD_FLAG_SHARED_PROXY, + &gdev->descs[0].flags); + return 0; + } + } + } + + /* + * This is not a shared GPIO proxy but it still may be the device + * exposing shared pins. Find them and create the proxy devices. + */ + list_for_each_entry(entry, &gpio_shared_list, list) { + if (!device_match_fwnode(&gdev->dev, entry->fwnode)) + continue; + + if (list_count_nodes(&entry->refs) <= 1) + continue; + + flags = &gdev->descs[entry->offset].flags; + + __set_bit(GPIOD_FLAG_SHARED, flags); + /* + * Shared GPIOs are not requested via the normal path. Make + * them inaccessible to anyone even before we register the + * chip. + */ + __set_bit(GPIOD_FLAG_REQUESTED, flags); + + pr_debug("GPIO %u owned by %s is shared by multiple consumers\n", + entry->offset, gpio_device_get_label(gdev)); + + list_for_each_entry(ref, &entry->refs, list) { + pr_debug("Setting up a shared GPIO entry for %s\n", + fwnode_get_name(ref->fwnode)); + + ret = gpio_shared_make_adev(gdev, ref); + if (ret) + return ret; + } + } + + return 0; +} + +void gpio_device_teardown_shared(struct gpio_device *gdev) +{ + struct gpio_shared_entry *entry; + struct gpio_shared_ref *ref; + + guard(mutex)(&gpio_shared_lock); + + list_for_each_entry(entry, &gpio_shared_list, list) { + if (!device_match_fwnode(&gdev->dev, entry->fwnode)) + continue; + + list_for_each_entry(ref, &entry->refs, list) { + gpiod_remove_lookup_table(ref->lookup); + kfree(ref->lookup->table[0].key); + kfree(ref->lookup); + ref->lookup = NULL; + gpio_shared_remove_adev(&ref->adev); + } + } +} + +static void gpio_shared_release(struct kref *kref) +{ + struct gpio_shared_entry *entry = + container_of(kref, struct gpio_shared_entry, ref); + struct gpio_shared_desc *shared_desc = entry->shared_desc; + + guard(mutex)(&gpio_shared_lock); + + gpio_device_put(shared_desc->desc->gdev); + if (shared_desc->can_sleep) + mutex_destroy(&shared_desc->mutex); + kfree(shared_desc); + entry->shared_desc = NULL; +} + +static void gpiod_shared_put(void *data) +{ + struct gpio_shared_entry *entry = data; + + lockdep_assert_not_held(&gpio_shared_lock); + + kref_put(&entry->ref, gpio_shared_release); +} + +static struct gpio_shared_desc * +gpiod_shared_desc_create(struct gpio_shared_entry *entry) +{ + struct gpio_shared_desc *shared_desc; + struct gpio_device *gdev; + + shared_desc = kzalloc(sizeof(*shared_desc), GFP_KERNEL); + if (!shared_desc) + return ERR_PTR(-ENOMEM); + + gdev = gpio_device_find_by_fwnode(entry->fwnode); + if (!gdev) { + kfree(shared_desc); + return ERR_PTR(-EPROBE_DEFER); + } + + shared_desc->desc = &gdev->descs[entry->offset]; + shared_desc->can_sleep = gpiod_cansleep(shared_desc->desc); + if (shared_desc->can_sleep) + mutex_init(&shared_desc->mutex); + else + spin_lock_init(&shared_desc->spinlock); + + return shared_desc; +} + +static struct gpio_shared_entry *gpiod_shared_find(struct auxiliary_device *adev) +{ + struct gpio_shared_desc *shared_desc; + struct gpio_shared_entry *entry; + struct gpio_shared_ref *ref; + + guard(mutex)(&gpio_shared_lock); + + list_for_each_entry(entry, &gpio_shared_list, list) { + list_for_each_entry(ref, &entry->refs, list) { + if (adev != &ref->adev) + continue; + + if (entry->shared_desc) { + kref_get(&entry->ref); + return entry; + } + + shared_desc = gpiod_shared_desc_create(entry); + if (IS_ERR(shared_desc)) + return ERR_CAST(shared_desc); + + kref_init(&entry->ref); + entry->shared_desc = shared_desc; + + pr_debug("Device %s acquired a reference to the shared GPIO %u owned by %s\n", + dev_name(&adev->dev), gpio_chip_hwgpio(shared_desc->desc), + gpio_device_get_label(shared_desc->desc->gdev)); + + + return entry; + } + } + + return ERR_PTR(-ENOENT); +} + +struct gpio_shared_desc *devm_gpiod_shared_get(struct device *dev) +{ + struct gpio_shared_entry *entry; + int ret; + + entry = gpiod_shared_find(to_auxiliary_dev(dev)); + if (IS_ERR(entry)) + return ERR_CAST(entry); + + ret = devm_add_action_or_reset(dev, gpiod_shared_put, entry); + if (ret) + return ERR_PTR(ret); + + return entry->shared_desc; +} +EXPORT_SYMBOL_GPL(devm_gpiod_shared_get); + +static void gpio_shared_drop_ref(struct gpio_shared_ref *ref) +{ + list_del(&ref->list); + kfree(ref->con_id); + ida_free(&gpio_shared_ida, ref->dev_id); + fwnode_handle_put(ref->fwnode); + kfree(ref); +} + +static void gpio_shared_drop_entry(struct gpio_shared_entry *entry) +{ + list_del(&entry->list); + fwnode_handle_put(entry->fwnode); + kfree(entry); +} + +/* + * This is only called if gpio_shared_init() fails so it's in fact __init and + * not __exit. + */ +static void __init gpio_shared_teardown(void) +{ + struct gpio_shared_entry *entry, *epos; + struct gpio_shared_ref *ref, *rpos; + + list_for_each_entry_safe(entry, epos, &gpio_shared_list, list) { + list_for_each_entry_safe(ref, rpos, &entry->refs, list) + gpio_shared_drop_ref(ref); + + gpio_shared_drop_entry(entry); + } +} + +static void gpio_shared_free_exclusive(void) +{ + struct gpio_shared_entry *entry, *epos; + + list_for_each_entry_safe(entry, epos, &gpio_shared_list, list) { + if (list_count_nodes(&entry->refs) > 1) + continue; + + gpio_shared_drop_ref(list_first_entry(&entry->refs, + struct gpio_shared_ref, + list)); + gpio_shared_drop_entry(entry); + } +} + +static int __init gpio_shared_init(void) +{ + int ret; + + /* Right now, we only support OF-based systems. */ + ret = gpio_shared_of_scan(); + if (ret) { + gpio_shared_teardown(); + pr_err("Failed to scan OF nodes for shared GPIOs: %d\n", ret); + return ret; + } + + gpio_shared_free_exclusive(); + + pr_debug("Finished scanning firmware nodes for shared GPIOs\n"); + return 0; +} +postcore_initcall(gpio_shared_init); diff --git a/drivers/gpio/gpiolib-shared.h b/drivers/gpio/gpiolib-shared.h new file mode 100644 index 000000000000..667dbdff3585 --- /dev/null +++ b/drivers/gpio/gpiolib-shared.h @@ -0,0 +1,71 @@ +/* SPDX-License-Identifier: GPL-2.0 */ + +#ifndef __LINUX_GPIO_SHARED_H +#define __LINUX_GPIO_SHARED_H + +#include +#include +#include +#include + +struct gpio_device; +struct gpio_desc; +struct device; + +#if IS_ENABLED(CONFIG_GPIO_SHARED) + +int gpio_device_setup_shared(struct gpio_device *gdev); +void gpio_device_teardown_shared(struct gpio_device *gdev); +int gpio_shared_add_proxy_lookup(struct device *consumer, unsigned long lflags); + +#else + +static inline int gpio_device_setup_shared(struct gpio_device *gdev) +{ + return 0; +} + +static inline void gpio_device_teardown_shared(struct gpio_device *gdev) { } + +static inline int gpio_shared_add_proxy_lookup(struct device *consumer, + unsigned long lflags) +{ + return 0; +} + +#endif /* CONFIG_GPIO_SHARED */ + +struct gpio_shared_desc { + struct gpio_desc *desc; + bool can_sleep; + unsigned long cfg; + unsigned int usecnt; + unsigned int highcnt; + union { + struct mutex mutex; + spinlock_t spinlock; + }; +}; + +struct gpio_shared_desc *devm_gpiod_shared_get(struct device *dev); + +DEFINE_LOCK_GUARD_1(gpio_shared_desc_lock, struct gpio_shared_desc, + if (_T->lock->can_sleep) + mutex_lock(&_T->lock->mutex); + else + spin_lock_irqsave(&_T->lock->spinlock, _T->flags), + if (_T->lock->can_sleep) + mutex_unlock(&_T->lock->mutex); + else + spin_unlock_irqrestore(&_T->lock->spinlock, _T->flags), + unsigned long flags) + +static inline void gpio_shared_lockdep_assert(struct gpio_shared_desc *shared_desc) +{ + if (shared_desc->can_sleep) + lockdep_assert_held(&shared_desc->mutex); + else + lockdep_assert_held(&shared_desc->spinlock); +} + +#endif /* __LINUX_GPIO_SHARED_H */ diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c index 9952e412da50..678d07dc768c 100644 --- a/drivers/gpio/gpiolib.c +++ b/drivers/gpio/gpiolib.c @@ -37,6 +37,7 @@ #include "gpiolib-acpi.h" #include "gpiolib-cdev.h" #include "gpiolib-of.h" +#include "gpiolib-shared.h" #include "gpiolib-swnode.h" #include "gpiolib-sysfs.h" #include "gpiolib.h" @@ -1200,6 +1201,10 @@ int gpiochip_add_data_with_key(struct gpio_chip *gc, void *data, if (ret) goto err_remove_irqchip_mask; + ret = gpio_device_setup_shared(gdev); + if (ret) + goto err_remove_irqchip; + /* * By first adding the chardev, and then adding the device, * we get a device node entry in sysfs under @@ -1211,10 +1216,13 @@ int gpiochip_add_data_with_key(struct gpio_chip *gc, void *data, if (gpiolib_initialized) { ret = gpiochip_setup_dev(gdev); if (ret) - goto err_remove_irqchip; + goto err_teardown_shared; } + return 0; +err_teardown_shared: + gpio_device_teardown_shared(gdev); err_remove_irqchip: gpiochip_irqchip_remove(gc); err_remove_irqchip_mask: @@ -1283,6 +1291,7 @@ void gpiochip_remove(struct gpio_chip *gc) /* Numb the device, cancelling all outstanding operations */ rcu_assign_pointer(gdev->chip, NULL); synchronize_srcu(&gdev->srcu); + gpio_device_teardown_shared(gdev); gpiochip_irqchip_remove(gc); acpi_gpiochip_remove(gc); of_gpiochip_remove(gc); @@ -3981,6 +3990,26 @@ int gpiod_set_consumer_name(struct gpio_desc *desc, const char *name) } EXPORT_SYMBOL_GPL(gpiod_set_consumer_name); +/** + * gpiod_is_shared() - check if this GPIO can be shared by multiple consumers + * @desc: GPIO to inspect + * + * Returns: + * True if this GPIO can be shared by multiple consumers at once. False if it's + * a regular, exclusive GPIO. + * + * Note: + * This function returning true does not mean that this GPIO is currently being + * shared. It means the GPIO core has registered the fact that the firmware + * configuration indicates that it can be shared by multiple consumers and is + * in charge of arbitrating the access. + */ +bool gpiod_is_shared(const struct gpio_desc *desc) +{ + return test_bit(GPIOD_FLAG_SHARED_PROXY, &desc->flags); +} +EXPORT_SYMBOL_GPL(gpiod_is_shared); + /** * gpiod_to_irq() - return the IRQ corresponding to a GPIO * @desc: gpio whose IRQ will be returned (already requested) @@ -4652,11 +4681,29 @@ struct gpio_desc *gpiod_find_and_request(struct device *consumer, scoped_guard(srcu, &gpio_devices_srcu) { desc = gpiod_fwnode_lookup(fwnode, consumer, con_id, idx, &flags, &lookupflags); + if (!IS_ERR_OR_NULL(desc) && + test_bit(GPIOD_FLAG_SHARED, &desc->flags)) { + /* + * We're dealing with a GPIO shared by multiple + * consumers. This is the moment to add the machine + * lookup table for the proxy device as previously + * we only knew the consumer's fwnode. + */ + ret = gpio_shared_add_proxy_lookup(consumer, lookupflags); + if (ret) + return ERR_PTR(ret); + + /* Trigger platform lookup for shared GPIO proxy. */ + desc = ERR_PTR(-ENOENT); + /* Trigger it even for fwnode-only gpiod_get(). */ + platform_lookup_allowed = true; + } + if (gpiod_not_found(desc) && platform_lookup_allowed) { /* * Either we are not using DT or ACPI, or their lookup - * did not return a result. In that case, use platform - * lookup as a fallback. + * did not return a result or this is a shared GPIO. In + * that case, use platform lookup as a fallback. */ dev_dbg(consumer, "using lookup tables for GPIO lookup\n"); @@ -4679,14 +4726,19 @@ struct gpio_desc *gpiod_find_and_request(struct device *consumer, return ERR_PTR(ret); /* - * This happens when there are several consumers for - * the same GPIO line: we just return here without - * further initialization. It is a bit of a hack. - * This is necessary to support fixed regulators. + * This happens when there are several consumers for the same + * GPIO line: we just return here without further + * initialization. It's a hack introduced long ago to support + * fixed regulators. We now have a better solution with + * automated scanning where affected platforms just need to + * select the provided Kconfig option. * - * FIXME: Make this more sane and safe. + * FIXME: Remove the GPIOD_FLAGS_BIT_NONEXCLUSIVE flag after + * making sure all platforms use the new mechanism. */ - dev_info(consumer, "nonexclusive access to GPIO for %s\n", name); + dev_info(consumer, + "nonexclusive access to GPIO for %s, consider updating your code to using gpio-shared-proxy\n", + name); return desc; } diff --git a/drivers/gpio/gpiolib.h b/drivers/gpio/gpiolib.h index 2a003a7311e7..abd870fb4a3b 100644 --- a/drivers/gpio/gpiolib.h +++ b/drivers/gpio/gpiolib.h @@ -204,6 +204,8 @@ struct gpio_desc { #define GPIOD_FLAG_EDGE_FALLING 17 /* GPIO CDEV detects falling edge events */ #define GPIOD_FLAG_EVENT_CLOCK_REALTIME 18 /* GPIO CDEV reports REALTIME timestamps in events */ #define GPIOD_FLAG_EVENT_CLOCK_HTE 19 /* GPIO CDEV reports hardware timestamps in events */ +#define GPIOD_FLAG_SHARED 20 /* GPIO is shared by multiple consumers */ +#define GPIOD_FLAG_SHARED_PROXY 21 /* GPIO is a virtual proxy to a physically shared pin. */ /* Connection label */ struct gpio_desc_label __rcu *label; diff --git a/drivers/regulator/core.c b/drivers/regulator/core.c index 2eab56df042e..53b2b2d3746f 100644 --- a/drivers/regulator/core.c +++ b/drivers/regulator/core.c @@ -2742,6 +2742,13 @@ static int regulator_ena_gpio_request(struct regulator_dev *rdev, mutex_lock(®ulator_list_mutex); + if (gpiod_is_shared(gpiod)) + /* + * The sharing of this GPIO pin is managed internally by + * GPIOLIB. We don't need to keep track of its enable count. + */ + goto skip_compare; + list_for_each_entry(pin, ®ulator_ena_gpio_list, list) { if (gpiod_is_equal(pin->gpiod, gpiod)) { rdev_dbg(rdev, "GPIO is already used\n"); @@ -2754,6 +2761,7 @@ static int regulator_ena_gpio_request(struct regulator_dev *rdev, return -ENOMEM; } +skip_compare: pin = new_pin; new_pin = NULL; diff --git a/include/linux/gpio/consumer.h b/include/linux/gpio/consumer.h index 00df68c51405..a8acb7c0b5af 100644 --- a/include/linux/gpio/consumer.h +++ b/include/linux/gpio/consumer.h @@ -167,6 +167,8 @@ int gpiod_cansleep(const struct gpio_desc *desc); int gpiod_to_irq(const struct gpio_desc *desc); int gpiod_set_consumer_name(struct gpio_desc *desc, const char *name); +bool gpiod_is_shared(const struct gpio_desc *desc); + /* Convert between the old gpio_ and new gpiod_ interfaces */ struct gpio_desc *gpio_to_desc(unsigned gpio); int desc_to_gpio(const struct gpio_desc *desc); @@ -520,6 +522,13 @@ static inline int gpiod_set_consumer_name(struct gpio_desc *desc, return -EINVAL; } +static inline bool gpiod_is_shared(const struct gpio_desc *desc) +{ + /* GPIO can never have been requested */ + WARN_ON(desc); + return false; +} + static inline struct gpio_desc *gpio_to_desc(unsigned gpio) { return NULL; diff --git a/include/linux/string.h b/include/linux/string.h index fdd3442c6bcb..929d05d1247c 100644 --- a/include/linux/string.h +++ b/include/linux/string.h @@ -562,4 +562,22 @@ static inline bool strstarts(const char *str, const char *prefix) return strncmp(str, prefix, strlen(prefix)) == 0; } +/** + * strends - Check if a string ends with another string. + * @str - NULL-terminated string to check against @suffix + * @suffix - NULL-terminated string defining the suffix to look for in @str + * + * Returns: + * True if @str ends with @suffix. False in all other cases. + */ +static inline bool strends(const char *str, const char *suffix) +{ + unsigned int str_len = strlen(str), suffix_len = strlen(suffix); + + if (str_len < suffix_len) + return false; + + return !(strcmp(str + str_len - suffix_len, suffix)); +} + #endif /* _LINUX_STRING_H_ */ diff --git a/lib/tests/string_kunit.c b/lib/tests/string_kunit.c index 0ed7448a26d3..f9a8e557ba77 100644 --- a/lib/tests/string_kunit.c +++ b/lib/tests/string_kunit.c @@ -602,6 +602,18 @@ static void string_test_memtostr(struct kunit *test) KUNIT_EXPECT_EQ(test, dest[7], '\0'); } +static void string_test_strends(struct kunit *test) +{ + KUNIT_EXPECT_TRUE(test, strends("foo-bar", "bar")); + KUNIT_EXPECT_TRUE(test, strends("foo-bar", "-bar")); + KUNIT_EXPECT_TRUE(test, strends("foobar", "foobar")); + KUNIT_EXPECT_TRUE(test, strends("foobar", "")); + KUNIT_EXPECT_FALSE(test, strends("bar", "foobar")); + KUNIT_EXPECT_FALSE(test, strends("", "foo")); + KUNIT_EXPECT_FALSE(test, strends("foobar", "ba")); + KUNIT_EXPECT_TRUE(test, strends("", "")); +} + static struct kunit_case string_test_cases[] = { KUNIT_CASE(string_test_memset16), KUNIT_CASE(string_test_memset32), @@ -623,6 +635,7 @@ static struct kunit_case string_test_cases[] = { KUNIT_CASE(string_test_strlcat), KUNIT_CASE(string_test_strtomem), KUNIT_CASE(string_test_memtostr), + KUNIT_CASE(string_test_strends), {} };