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    Subject[PATCH 08/13] gpio: sysfs: implement class.get_dependencies()
    Date
    So the GPIO subsystem can be queried about the dependencies of nodes
    that consume GPIOs, as specified in bindings/gpio/gpio.txt.

    Signed-off-by: Tomeu Vizoso <tomeu.vizoso@collabora.com>
    ---
    drivers/gpio/gpiolib-sysfs.c | 81 ++++++++++++++++++++++++++++++++++++++++++++
    1 file changed, 81 insertions(+)

    diff --git a/drivers/gpio/gpiolib-sysfs.c b/drivers/gpio/gpiolib-sysfs.c
    index b57ed8e..d0a7fb1 100644
    --- a/drivers/gpio/gpiolib-sysfs.c
    +++ b/drivers/gpio/gpiolib-sysfs.c
    @@ -7,6 +7,7 @@
    #include <linux/interrupt.h>
    #include <linux/kdev_t.h>
    #include <linux/slab.h>
    +#include <linux/of.h>

    #include "gpiolib.h"

    @@ -515,6 +516,85 @@ done:
    return status ? : len;
    }

    +static bool strends(const char *str, const char *postfix)
    +{
    + if (strlen(str) < strlen(postfix))
    + return false;
    +
    + return strcmp(str + strlen(str) - strlen(postfix), postfix) == 0;
    +}
    +
    +static void add_dependency(struct fwnode_handle *fwnode,
    + struct list_head *list)
    +{
    + struct fwnode_dependency *dep;
    +
    + dep = kzalloc(sizeof(*dep), GFP_KERNEL);
    + if (!dep)
    + return;
    +
    + INIT_LIST_HEAD(&dep->dependency);
    + dep->fwnode = fwnode;
    +
    + list_add_tail(&dep->dependency, list);
    +}
    +
    +struct list_head *gpio_get_dependencies(struct fwnode_handle *fwnode)
    +{
    + struct device_node *np = of_node(fwnode);
    + struct list_head *list = NULL;
    + struct property *pp;
    + struct of_phandle_args pspec;
    + int count, i, ret;
    +
    + if (!is_of_node(fwnode))
    + return NULL;
    +
    + np = of_node(fwnode);
    + if (!np)
    + return NULL;
    +
    + list = kzalloc(sizeof(*list), GFP_KERNEL);
    + if (!list)
    + return NULL;
    +
    + INIT_LIST_HEAD(list);
    +
    + for_each_property_of_node(np, pp) {
    + if (strcmp(pp->name, "gpio") &&
    + !strends(pp->name, "-gpios") &&
    + !strends(pp->name, "-gpio"))
    + continue;
    +
    + count = of_count_phandle_with_args(np, pp->name,
    + "#gpio-cells");
    + for (i = 0; i < count; i++) {
    + ret = of_parse_phandle_with_args(np, pp->name,
    + "#gpio-cells", i,
    + &pspec);
    + if (ret || !pspec.np)
    + continue;
    +
    + add_dependency(&pspec.np->fwnode, list);
    +
    + of_node_put(pspec.np);
    + }
    + }
    +
    + for (i = 0;; i++) {
    + ret = of_parse_phandle_with_fixed_args(np, "gpio-ranges", 3,
    + i, &pspec);
    + if (ret)
    + break;
    +
    + add_dependency(&pspec.np->fwnode, list);
    +
    + of_node_put(pspec.np);
    + }
    +
    + return list;
    +}
    +
    static struct class_attribute gpio_class_attrs[] = {
    __ATTR(export, 0200, NULL, export_store),
    __ATTR(unexport, 0200, NULL, unexport_store),
    @@ -526,6 +606,7 @@ static struct class gpio_class = {
    .owner = THIS_MODULE,

    .class_attrs = gpio_class_attrs,
    + .get_dependencies = gpio_get_dependencies,
    };


    --
    2.4.1


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