From: Bartosz Golaszewski Date: Mon, 22 Dec 2025 10:01:28 +0000 (+0100) Subject: gpio: shared: allow sharing a reset-gpios pin between reset-gpio and gpiolib X-Git-Tag: v6.19-rc5~23^2~9 X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=49416483a953662aa53c6d9bef651757d4a95ba5;p=thirdparty%2Fkernel%2Flinux.git gpio: shared: allow sharing a reset-gpios pin between reset-gpio and gpiolib We currently support sharing GPIOs between multiple devices whose drivers use either the GPIOLIB API *OR* the reset control API but not both at the same time. There's an unlikely corner-case where a reset-gpios pin can be shared by one driver using the GPIOLIB API and a second using the reset API. This will currently not work as the reset-gpio consumers are not described in firmware at the time of scanning so the shared GPIO just chooses one of the proxies created for the consumers when the reset-gpio driver performs the lookup. This can of course conflict in the case described above. In order to fix it: if we deal with the "reset-gpios" pin that's shared acconding to the firmware node setup, create a proxy for each described consumer as well as another one for the potential reset-gpio device. To that end: rework the matching to take this into account. Fixes: 7b78b26757e0 ("gpio: shared: handle the reset-gpios corner case") Link: https://lore.kernel.org/r/20251222-gpio-shared-reset-gpio-proxy-v1-3-8d4bba7d8c14@oss.qualcomm.com Signed-off-by: Bartosz Golaszewski --- diff --git a/drivers/gpio/gpiolib-shared.c b/drivers/gpio/gpiolib-shared.c index f589109590c7..baf7e07a3bb8 100644 --- a/drivers/gpio/gpiolib-shared.c +++ b/drivers/gpio/gpiolib-shared.c @@ -76,6 +76,56 @@ gpio_shared_find_entry(struct fwnode_handle *controller_node, return NULL; } +static struct gpio_shared_ref *gpio_shared_make_ref(struct fwnode_handle *fwnode, + const char *con_id, + enum gpiod_flags flags) +{ + char *con_id_cpy __free(kfree) = NULL; + + struct gpio_shared_ref *ref __free(kfree) = kzalloc(sizeof(*ref), GFP_KERNEL); + if (!ref) + return NULL; + + if (con_id) { + con_id_cpy = kstrdup(con_id, GFP_KERNEL); + if (!con_id_cpy) + return NULL; + } + + ref->dev_id = ida_alloc(&gpio_shared_ida, GFP_KERNEL); + if (ref->dev_id < 0) + return NULL; + + ref->flags = flags; + ref->con_id = no_free_ptr(con_id_cpy); + ref->fwnode = fwnode; + mutex_init(&ref->lock); + + return no_free_ptr(ref); +} + +static int gpio_shared_setup_reset_proxy(struct gpio_shared_entry *entry, + enum gpiod_flags flags) +{ + struct gpio_shared_ref *ref; + + list_for_each_entry(ref, &entry->refs, list) { + if (!ref->fwnode && ref->con_id && strcmp(ref->con_id, "reset") == 0) + return 0; + } + + ref = gpio_shared_make_ref(NULL, "reset", flags); + if (!ref) + return -ENOMEM; + + list_add_tail(&ref->list, &entry->refs); + + pr_debug("Created a secondary shared GPIO reference for potential reset-gpio device for GPIO %u at %s\n", + entry->offset, fwnode_get_name(entry->fwnode)); + + return 0; +} + /* Handle all special nodes that we should ignore. */ static bool gpio_shared_of_node_ignore(struct device_node *node) { @@ -106,6 +156,7 @@ static int gpio_shared_of_traverse(struct device_node *curr) size_t con_id_len, suffix_len; struct fwnode_handle *fwnode; struct of_phandle_args args; + struct gpio_shared_ref *ref; struct property *prop; unsigned int offset; const char *suffix; @@ -138,6 +189,7 @@ static int gpio_shared_of_traverse(struct device_node *curr) for (i = 0; i < count; i++) { struct device_node *np __free(device_node) = NULL; + char *con_id __free(kfree) = NULL; ret = of_parse_phandle_with_args(curr, prop->name, "#gpio-cells", i, @@ -182,15 +234,6 @@ static int gpio_shared_of_traverse(struct device_node *curr) 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]; - mutex_init(&ref->lock); - if (strends(prop->name, "gpios")) suffix = "-gpios"; else if (strends(prop->name, "gpio")) @@ -202,27 +245,32 @@ static int gpio_shared_of_traverse(struct device_node *curr) /* 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) + con_id = kstrdup(prop->name, GFP_KERNEL); + if (!con_id) return -ENOMEM; - con_id_len = strlen(ref->con_id); + con_id_len = strlen(con_id); suffix_len = strlen(suffix); - ref->con_id[con_id_len - suffix_len] = '\0'; + 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); + ref = gpio_shared_make_ref(fwnode_handle_get(of_fwnode_handle(curr)), + con_id, args.args[1]); + if (!ref) 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); + list_add_tail(&ref->list, &entry->refs); + + if (strcmp(prop->name, "reset-gpios") == 0) { + ret = gpio_shared_setup_reset_proxy(entry, args.args[1]); + if (ret) + return ret; + } } } @@ -306,20 +354,16 @@ static bool gpio_shared_dev_is_reset_gpio(struct device *consumer, struct fwnode_handle *reset_fwnode = dev_fwnode(consumer); struct fwnode_reference_args ref_args, aux_args; struct device *parent = consumer->parent; + struct gpio_shared_ref *real_ref; bool match; int ret; + lockdep_assert_held(&ref->lock); + /* The reset-gpio device must have a parent AND a firmware node. */ if (!parent || !reset_fwnode) return false; - /* - * FIXME: use device_is_compatible() once the reset-gpio drivers gains - * a compatible string which it currently does not have. - */ - if (!strstarts(dev_name(consumer), "reset.gpio.")) - return false; - /* * Parent of the reset-gpio auxiliary device is the GPIO chip whose * fwnode we stored in the entry structure. @@ -328,33 +372,56 @@ static bool gpio_shared_dev_is_reset_gpio(struct device *consumer, return false; /* - * The device associated with the shared reference's firmware node is - * the consumer of the reset control exposed by the reset-gpio device. - * It must have a "reset-gpios" property that's referencing the entry's - * firmware node. - * - * The reference args must agree between the real consumer and the - * auxiliary reset-gpio device. + * Now we need to find the actual pin we want to assign to this + * reset-gpio device. To that end: iterate over the list of references + * of this entry and see if there's one, whose reset-gpios property's + * arguments match the ones from this consumer's node. */ - ret = fwnode_property_get_reference_args(ref->fwnode, "reset-gpios", - NULL, 2, 0, &ref_args); - if (ret) - return false; + list_for_each_entry(real_ref, &entry->refs, list) { + if (!real_ref->fwnode) + continue; + + /* + * The device associated with the shared reference's firmware + * node is the consumer of the reset control exposed by the + * reset-gpio device. It must have a "reset-gpios" property + * that's referencing the entry's firmware node. + * + * The reference args must agree between the real consumer and + * the auxiliary reset-gpio device. + */ + ret = fwnode_property_get_reference_args(real_ref->fwnode, + "reset-gpios", + NULL, 2, 0, &ref_args); + if (ret) + continue; + + ret = fwnode_property_get_reference_args(reset_fwnode, "reset-gpios", + NULL, 2, 0, &aux_args); + if (ret) { + fwnode_handle_put(ref_args.fwnode); + continue; + } + + match = ((ref_args.fwnode == entry->fwnode) && + (aux_args.fwnode == entry->fwnode) && + (ref_args.args[0] == aux_args.args[0])); - ret = fwnode_property_get_reference_args(reset_fwnode, "reset-gpios", - NULL, 2, 0, &aux_args); - if (ret) { fwnode_handle_put(ref_args.fwnode); - return false; - } + fwnode_handle_put(aux_args.fwnode); + + if (!match) + continue; - match = ((ref_args.fwnode == entry->fwnode) && - (aux_args.fwnode == entry->fwnode) && - (ref_args.args[0] == aux_args.args[0])); + /* + * Reuse the fwnode of the real device, next time we'll use it + * in the normal path. + */ + ref->fwnode = fwnode_handle_get(real_ref->fwnode); + return true; + } - fwnode_handle_put(ref_args.fwnode); - fwnode_handle_put(aux_args.fwnode); - return match; + return false; } #else static bool gpio_shared_dev_is_reset_gpio(struct device *consumer, @@ -379,12 +446,20 @@ int gpio_shared_add_proxy_lookup(struct device *consumer, const char *con_id, list_for_each_entry(entry, &gpio_shared_list, list) { list_for_each_entry(ref, &entry->refs, list) { - if (!device_match_fwnode(consumer, ref->fwnode) && - !gpio_shared_dev_is_reset_gpio(consumer, entry, ref)) - continue; - guard(mutex)(&ref->lock); + /* + * FIXME: use device_is_compatible() once the reset-gpio + * drivers gains a compatible string which it currently + * does not have. + */ + if (!ref->fwnode && strstarts(dev_name(consumer), "reset.gpio.")) { + if (!gpio_shared_dev_is_reset_gpio(consumer, entry, ref)) + continue; + } else if (!device_match_fwnode(consumer, ref->fwnode)) { + continue; + } + if ((!con_id && ref->con_id) || (con_id && !ref->con_id) || (con_id && ref->con_id && strcmp(con_id, ref->con_id) != 0)) continue; @@ -471,8 +546,9 @@ int gpio_device_setup_shared(struct gpio_device *gdev) 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)); + pr_debug("Setting up a shared GPIO entry for %s (con_id: '%s')\n", + fwnode_get_name(ref->fwnode) ?: "(no fwnode)", + ref->con_id ?: "(none)"); ret = gpio_shared_make_adev(gdev, entry, ref); if (ret)