Devices sharing a reset GPIO could use the reset framework for coordinated handling of that shared GPIO line. We have several cases of such needs, at least for Devicetree-based platforms.
If Devicetree-based device requests a reset line which is missing but there is a reset-gpios property, instantiate a new "reset-gpio" platform device which will handle such reset line. This allows seamless handling of such shared reset-gpios without need of changing Devicetree binding [1].
The "reset-gpio" driver follows shortly.
Link: https://lore.kernel.org/all/YXi5CUCEi7YmNxXM@robh.at.kernel.org/ Cc: Bartosz Golaszewski brgl@bgdev.pl Cc: Sean Anderson sean.anderson@seco.com Signed-off-by: Krzysztof Kozlowski krzysztof.kozlowski@linaro.org --- drivers/reset/core.c | 70 +++++++++++++++++++++++++++----- include/linux/reset-controller.h | 2 + 2 files changed, 61 insertions(+), 11 deletions(-)
diff --git a/drivers/reset/core.c b/drivers/reset/core.c index 4d5a78d3c085..a1f0f515a7e0 100644 --- a/drivers/reset/core.c +++ b/drivers/reset/core.c @@ -10,9 +10,12 @@ #include <linux/export.h> #include <linux/kernel.h> #include <linux/kref.h> +#include <linux/gpio/consumer.h> #include <linux/module.h> #include <linux/of.h> +#include <linux/of_gpio.h> #include <linux/acpi.h> +#include <linux/platform_device.h> #include <linux/reset.h> #include <linux/reset-controller.h> #include <linux/slab.h> @@ -813,13 +816,59 @@ static void __reset_control_put_internal(struct reset_control *rstc) kref_put(&rstc->refcnt, __reset_control_release); }
+static int __reset_add_reset_gpio_device(struct device_node *node, + const struct gpio_desc **out) +{ + struct platform_device *pdev; + int gpio; + + /* Don't care about deprecated '-gpio' suffix. */ + gpio = of_get_named_gpio(node, "reset-gpios", 0); + if (!gpio_is_valid(gpio)) + return gpio; + + pdev = platform_device_register_data(NULL, "reset-gpio", + PLATFORM_DEVID_AUTO, &node, + sizeof(node)); + if (!IS_ERR(pdev)) + *out = gpio_to_desc(gpio); + + return PTR_ERR_OR_ZERO(pdev); +} + +static struct reset_controller_dev *__reset_find_rcdev(const struct of_phandle_args *args, + const void *cookie) +{ + struct reset_controller_dev *r, *rcdev; + + lockdep_assert_held(&reset_list_mutex); + + rcdev = NULL; + list_for_each_entry(r, &reset_controller_list, list) { + if (args && args->np) { + if (args->np == r->of_node) { + rcdev = r; + break; + } + } else if (cookie) { + if (cookie == r->cookie) { + rcdev = r; + break; + } + } + } + + return rcdev; +} + struct reset_control * __of_reset_control_get(struct device_node *node, const char *id, int index, bool shared, bool optional, bool acquired) { + const struct gpio_desc *gpio = NULL; + struct of_phandle_args args = {0}; struct reset_control *rstc; - struct reset_controller_dev *r, *rcdev; - struct of_phandle_args args; + struct reset_controller_dev *rcdev; int rstc_id; int ret;
@@ -839,17 +888,16 @@ __of_reset_control_get(struct device_node *node, const char *id, int index, index, &args); if (ret == -EINVAL) return ERR_PTR(ret); - if (ret) - return optional ? NULL : ERR_PTR(ret); + if (ret) { + ret = __reset_add_reset_gpio_device(node, &gpio); + if (ret) + return optional ? NULL : ERR_PTR(ret); + + args.args_count = 1; /* reset-gpio has only one reset line */ + }
mutex_lock(&reset_list_mutex); - rcdev = NULL; - list_for_each_entry(r, &reset_controller_list, list) { - if (args.np == r->of_node) { - rcdev = r; - break; - } - } + rcdev = __reset_find_rcdev(&args, gpio);
if (!rcdev) { rstc = ERR_PTR(-EPROBE_DEFER); diff --git a/include/linux/reset-controller.h b/include/linux/reset-controller.h index 0fa4f60e1186..c0a99a8ea29e 100644 --- a/include/linux/reset-controller.h +++ b/include/linux/reset-controller.h @@ -61,6 +61,7 @@ struct reset_control_lookup { * @dev: corresponding driver model device struct * @of_node: corresponding device tree node as phandle target * @of_reset_n_cells: number of cells in reset line specifiers + * @cookie: for reset-gpios controllers: corresponding GPIO instead of of_node * @of_xlate: translation function to translate from specifier as found in the * device tree to id as given to the reset control ops, defaults * to :c:func:`of_reset_simple_xlate`. @@ -74,6 +75,7 @@ struct reset_controller_dev { struct device *dev; struct device_node *of_node; int of_reset_n_cells; + const void *cookie; int (*of_xlate)(struct reset_controller_dev *rcdev, const struct of_phandle_args *reset_spec); unsigned int nr_resets;