gpio: sim: allow to mark simulated lines as invalid

Add a new line-level, boolean property to the gpio-sim configfs
interface called 'valid'. It's set by default and the user can unset it
to make the line be included in the standard `gpio-reserved-ranges`
property when the chip is registered with GPIO core. This allows users
to specify which lines should not be available for requesting as GPIOs.

Link: https://lore.kernel.org/r/20250630130358.40352-1-brgl@bgdev.pl
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>

diff --git a/Documentation/admin-guide/gpio/gpio-sim.rst b/Documentation/admin-guide/gpio/gpio-sim.rst
index 35d49ccd49e0a3c3c071b91f9acf1408f650a308..f5135a14ef2e01fcfc613a68f5101ed459aede42 100644 (file)
--- a/Documentation/admin-guide/gpio/gpio-sim.rst
+++ b/Documentation/admin-guide/gpio/gpio-sim.rst
@@ -50,8 +50,11 @@ the number of lines exposed by this bank.
 
 **Attribute:** ``/config/gpio-sim/gpio-device/gpio-bankX/lineY/name``
 
-This group represents a single line at the offset Y. The 'name' attribute
-allows to set the line name as represented by the 'gpio-line-names' property.
+**Attribute:** ``/config/gpio-sim/gpio-device/gpio-bankX/lineY/valid``
+
+This group represents a single line at the offset Y. The ``valid`` attribute
+indicates whether the line can be used as GPIO. The ``name`` attribute allows
+to set the line name as represented by the 'gpio-line-names' property.
 
 **Item:** ``/config/gpio-sim/gpio-device/gpio-bankX/lineY/hog``
 

diff --git a/drivers/gpio/gpio-sim.c b/drivers/gpio/gpio-sim.c
index f638219a7c4f009290f72cd12caa4c52989f8a9c..9503296422fd2377f59292fa7b9250fc77b892c4 100644 (file)
--- a/drivers/gpio/gpio-sim.c
+++ b/drivers/gpio/gpio-sim.c
@@ -39,7 +39,7 @@
 #include "dev-sync-probe.h"
 
 #define GPIO_SIM_NGPIO_MAX     1024
-#define GPIO_SIM_PROP_MAX      4 /* Max 3 properties + sentinel. */
+#define GPIO_SIM_PROP_MAX      5 /* Max 4 properties + sentinel. */
 #define GPIO_SIM_NUM_ATTRS     3 /* value, pull and sentinel */
 
 static DEFINE_IDA(gpio_sim_ida);
@@ -629,6 +629,7 @@ struct gpio_sim_line {
 
        unsigned int offset;
        char *name;
+       bool valid;
 
        /* There can only be one hog per line. */
        struct gpio_sim_hog *hog;
@@ -744,6 +745,36 @@ gpio_sim_set_line_names(struct gpio_sim_bank *bank, char **line_names)
        }
 }
 
+static unsigned int gpio_sim_get_reserved_ranges_size(struct gpio_sim_bank *bank)
+{
+       struct gpio_sim_line *line;
+       unsigned int size = 0;
+
+       list_for_each_entry(line, &bank->line_list, siblings) {
+               if (line->valid)
+                       continue;
+
+               size += 2;
+       }
+
+       return size;
+}
+
+static void gpio_sim_set_reserved_ranges(struct gpio_sim_bank *bank,
+                                        u32 *ranges)
+{
+       struct gpio_sim_line *line;
+       int i = 0;
+
+       list_for_each_entry(line, &bank->line_list, siblings) {
+               if (line->valid)
+                       continue;
+
+               ranges[i++] = line->offset;
+               ranges[i++] = 1;
+       }
+}
+
 static void gpio_sim_remove_hogs(struct gpio_sim_device *dev)
 {
        struct gpiod_hog *hog;
@@ -844,9 +875,10 @@ static struct fwnode_handle *
 gpio_sim_make_bank_swnode(struct gpio_sim_bank *bank,
                          struct fwnode_handle *parent)
 {
+       unsigned int prop_idx = 0, line_names_size, ranges_size;
        struct property_entry properties[GPIO_SIM_PROP_MAX];
-       unsigned int prop_idx = 0, line_names_size;
        char **line_names __free(kfree) = NULL;
+       u32 *ranges __free(kfree) = NULL;
 
        memset(properties, 0, sizeof(properties));
 
@@ -870,6 +902,19 @@ gpio_sim_make_bank_swnode(struct gpio_sim_bank *bank,
                                                line_names, line_names_size);
        }
 
+       ranges_size = gpio_sim_get_reserved_ranges_size(bank);
+       if (ranges_size) {
+               ranges = kcalloc(ranges_size, sizeof(u32), GFP_KERNEL);
+               if (!ranges)
+                       return ERR_PTR(-ENOMEM);
+
+               gpio_sim_set_reserved_ranges(bank, ranges);
+
+               properties[prop_idx++] = PROPERTY_ENTRY_U32_ARRAY_LEN(
+                                               "gpio-reserved-ranges",
+                                               ranges, ranges_size);
+       }
+
        return fwnode_create_software_node(properties, parent);
 }
 
@@ -1189,8 +1234,41 @@ static ssize_t gpio_sim_line_config_name_store(struct config_item *item,
 
 CONFIGFS_ATTR(gpio_sim_line_config_, name);
 
+static ssize_t
+gpio_sim_line_config_valid_show(struct config_item *item, char *page)
+{
+       struct gpio_sim_line *line = to_gpio_sim_line(item);
+       struct gpio_sim_device *dev = gpio_sim_line_get_device(line);
+
+       guard(mutex)(&dev->lock);
+
+       return sprintf(page, "%c\n", line->valid ? '1' : '0');
+}
+
+static ssize_t gpio_sim_line_config_valid_store(struct config_item *item,
+                                               const char *page, size_t count)
+{
+       struct gpio_sim_line *line = to_gpio_sim_line(item);
+       struct gpio_sim_device *dev = gpio_sim_line_get_device(line);
+       bool valid;
+       int ret;
+
+       ret = kstrtobool(page, &valid);
+       if (ret)
+               return ret;
+
+       guard(mutex)(&dev->lock);
+
+       line->valid = valid;
+
+       return count;
+}
+
+CONFIGFS_ATTR(gpio_sim_line_config_, valid);
+
 static struct configfs_attribute *gpio_sim_line_config_attrs[] = {
        &gpio_sim_line_config_attr_name,
+       &gpio_sim_line_config_attr_valid,
        NULL
 };
 
@@ -1399,6 +1477,7 @@ gpio_sim_bank_config_make_line_group(struct config_group *group,
 
        line->parent = bank;
        line->offset = offset;
+       line->valid = true;
        list_add_tail(&line->siblings, &bank->line_list);
 
        return &line->group;