On Fr, 2024-01-12 at 17:36 +0100, Krzysztof Kozlowski wrote:
[...]
> diff --git a/drivers/reset/core.c b/drivers/reset/core.c
> index 4d5a78d3c085..86e33a703ad2 100644
> --- a/drivers/reset/core.c
> +++ b/drivers/reset/core.c
[...]
> @@ -813,13 +832,183 @@ static void __reset_control_put_internal(struct reset_control *rstc)
> kref_put(&rstc->refcnt, __reset_control_release);
> }
>
> +static bool __reset_gpios_args_match(const struct of_phandle_args *a1,
> + const struct of_phandle_args *a2)
> +{
> + unsigned int i;
> +
> + if (!a2)
> + return false;
> +
> + if (a1->args_count != a2->args_count)
> + return false;
> +
> + for (i = 0; i < a1->args_count; i++)
> + if (a1->args[i] != a2->args[i])
> + return false;
> +
> + return true;
> +}
How about making this
return a2 &&
a1->np == a2->np &&
a1->args_count == a2->args_count &&
!memcmp(a1->args, a2->args, sizeof(a1->args[0]) * a1->args_count);
?
There's similar code in include/linux/cpufreq.h, maybe this could later
be lifted into a common of_phandle_args_equal().
> +
> +static int __reset_add_reset_gpio_lookup(int id, struct device_node *np,
> + unsigned int gpio,
> + unsigned int of_flags)
> +{
> + struct gpiod_lookup_table *lookup __free(kfree) = NULL;
> + struct gpio_device *gdev __free(gpio_device_put) = NULL;
> + char *label __free(kfree) = NULL;
> + unsigned int lookup_flags;
> +
> + /*
> + * Later we map GPIO flags between OF and Linux, however not all
> + * constants from include/dt-bindings/gpio/gpio.h and
> + * include/linux/gpio/machine.h match each other.
> + */
> + if (of_flags > GPIO_ACTIVE_LOW) {
> + pr_err("reset-gpio code does not support GPIO flags %u for GPIO %u\n",
> + of_flags, gpio);
> + return -EINVAL;
> + }
> +
> + gdev = gpio_device_find_by_fwnode(of_fwnode_handle(np));
> + if (!gdev)
> + return -EPROBE_DEFER;
> +
> + label = kstrdup(gpio_device_get_label(gdev), GFP_KERNEL);
> + if (!label)
> + return -EINVAL;
The kstrdup() failure looks like it should be -ENOMEM to me.
I'd check the gpio_device_get_label(gdev) return value separately.
Is this going to be in v6.8-rc1, or does using gpio_device_get_label()
introduce a dependency?
> +
> + /* Size: one lookup entry plus sentinel */
> + lookup = kzalloc(struct_size(lookup, table, 2), GFP_KERNEL);
> + if (!lookup)
> + return -ENOMEM;
> +
> + lookup->dev_id = kasprintf(GFP_KERNEL, "reset-gpio.%d", id);
> + if (!lookup->dev_id)
> + return -ENOMEM;
> +
> + lookup_flags = GPIO_PERSISTENT;
> + lookup_flags |= of_flags & GPIO_ACTIVE_LOW;
> + lookup->table[0] = GPIO_LOOKUP(no_free_ptr(label), gpio, "reset",
> + lookup_flags);
> +
> + gpiod_add_lookup_table(no_free_ptr(lookup));
> +
> + return 0;
> +}
> +
> +/*
> + * @reset_args: phandle to the GPIO provider with all the args like GPIO number
s/reset_//
> + */
> +static int __reset_add_reset_gpio_device(const struct of_phandle_args *args)
> +{
> + struct reset_gpio_lookup *rgpio_dev;
> + struct platform_device *pdev;
> + int id, ret;
> +
> + /*
> + * Registering reset-gpio device might cause immediate
> + * bind, resulting in its probe() registering new reset controller thus
> + * taking reset_list_mutex lock via reset_controller_register().
> + */
> + lockdep_assert_not_held(&reset_list_mutex);
> +
> + mutex_lock(&reset_gpio_lookup_mutex);
> +
> + list_for_each_entry(rgpio_dev, &reset_gpio_lookup_list, list) {
> + if (args->np == rgpio_dev->of_args.np) {
> + if (__reset_gpios_args_match(args, &rgpio_dev->of_args))
> + goto out; /* Already on the list, done */
> + }
> + }
> +
> + id = ida_alloc(&reset_gpio_ida, GFP_KERNEL);
> + if (id < 0) {
> + ret = id;
> + goto err_unlock;
> + }
> +
> + /*
> + * Not freed in normal path, persisent subsystem data (which is assumed
> + * also in the reset-gpio driver).
> + */
> + rgpio_dev = kzalloc(sizeof(*rgpio_dev), GFP_KERNEL);
> + if (!rgpio_dev) {
> + ret = -ENOMEM;
> + goto err_ida_free;
> + }
> +
> + ret = __reset_add_reset_gpio_lookup(id, args->np, args->args[0],
> + args->args[1]);
> + if (ret < 0)
> + goto err_kfree;
> +
> + rgpio_dev->of_args = *args;
> + /*
> + * We keep the device_node reference, but of_args.np is put at the end
> + * of __of_reset_control_get(), so get it one more time.
> + * Hold reference as long as rgpio_dev memory is valid.
> + */
> + of_node_get(rgpio_dev->of_args.np);
> + pdev = platform_device_register_data(NULL, "reset-gpio", id,
> + &rgpio_dev->of_args,
> + sizeof(rgpio_dev->of_args));
> + ret = PTR_ERR_OR_ZERO(pdev);
> + if (ret)
> + goto err_put;
> +
> + list_add(&rgpio_dev->list, &reset_gpio_lookup_list);
> +
> +out:
> + mutex_unlock(&reset_gpio_lookup_mutex);
> +
> + return 0;
> +
> +err_put:
> + of_node_put(rgpio_dev->of_args.np);
> +err_kfree:
> + kfree(rgpio_dev);
> +err_ida_free:
> + ida_free(&reset_gpio_ida, id);
> +err_unlock:
> + mutex_unlock(&reset_gpio_lookup_mutex);
> +
> + return ret;
> +}
> +
> +static struct reset_controller_dev *__reset_find_rcdev(const struct of_phandle_args *args,
> + bool gpio_fallback)
> +{
> + struct reset_controller_dev *r, *rcdev;
Now that this is moved into a function, there's no need for the r,
rcdev split anymore. Just return a match when found, and NULL at the
end:
struct reset_controller_dev *rcdev;
> +
> + lockdep_assert_held(&reset_list_mutex);
> +
> + rcdev = NULL;
> + list_for_each_entry(r, &reset_controller_list, list) {
list_for_each_entry(rcdev, &reset_controller_list, list) {
> + if (args->np == r->of_node) {
> + if (gpio_fallback) {
> + if (__reset_gpios_args_match(args, r->of_args)) {
> + rcdev = r;
> + break;
return rcdev;
> + }
> + } else {
> + rcdev = r;
> + break;
> + }
> + }
With the np check moved into __reset_gpios_args_match() above, the
whole loop could be turned into:
if (gpio_fallback) {
if (__reset_gpios_args_match(args, rcdev->of_args))
return rcdev;
} else {
if (args->np == rcdev->of_node)
return rcdev;
}
Explicitly checking against rcdev->of_args->np instead of rcdev-
>of_node in gpio_fallback mode could avoid false positives in case
anybody ever creates a combined GPIO and reset controller device and
then uses its GPIOs to drive a shared reset line..
> + }
> +
> + return rcdev;
return NULL;
> +}
>
> struct reset_control *
> __of_reset_control_get(struct device_node *node, const char *id, int index,
> bool shared, bool optional, bool acquired)
> {
> + struct of_phandle_args args = {0};
Is this still needed?
> + bool gpio_fallback = false;
> 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;
>
> @@ -839,39 +1028,49 @@ __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) {
> + /*
> + * There can be only one reset-gpio for regular devices, so
> + * don't bother with GPIO index.
> + */
> + ret = of_parse_phandle_with_args(node, "reset-gpios", "#gpio-cells",
> + 0, &args);
> + if (ret)
> + return optional ? NULL : ERR_PTR(ret);
>
> - 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;
> + gpio_fallback = true;
> +
> + ret = __reset_add_reset_gpio_device(&args);
> + if (ret) {
> + rstc = ERR_PTR(ret);
> + goto out_put;
> }
> }
>
> + mutex_lock(&reset_list_mutex);
> + rcdev = __reset_find_rcdev(&args, gpio_fallback);
> if (!rcdev) {
> rstc = ERR_PTR(-EPROBE_DEFER);
> - goto out;
> + goto out_unlock;
> }
>
> if (WARN_ON(args.args_count != rcdev->of_reset_n_cells)) {
Nice. I like that the __of_reset_control_get() changes are much less
invasive now.
> rstc = ERR_PTR(-EINVAL);
> - goto out;
> + goto out_unlock;
> }
>
> rstc_id = rcdev->of_xlate(rcdev, &args);
> if (rstc_id < 0) {
> rstc = ERR_PTR(rstc_id);
> - goto out;
> + goto out_unlock;
> }
>
> /* reset_list_mutex also protects the rcdev's reset_control list */
> rstc = __reset_control_get_internal(rcdev, rstc_id, shared, acquired);
>
> -out:
> +out_unlock:
> mutex_unlock(&reset_list_mutex);
> +out_put:
> of_node_put(args.np);
>
> return rstc;
> diff --git a/include/linux/reset-controller.h b/include/linux/reset-controller.h
> index 0fa4f60e1186..e064473215de 100644
> --- a/include/linux/reset-controller.h
> +++ b/include/linux/reset-controller.h
> @@ -61,6 +61,9 @@ 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
> + * TODO: of_args have of_node, so we have here duplication
Any plans what to do about this? With the above changes we could
mandate that either of_node or of_args should be set, never both.
> + * @of_args: for reset-gpios controllers: corresponding phandle args with GPIO
> + * number complementing of_node
regards
Philipp
