[PATCH v3] gpio: mockup: Allow probing from device tree

[Vincent Whitchurch <vincent.whitchurch@xxxxxxxx>]

Allow the mockup driver to be probed via the device tree without any
module parameters, allowing it to be used to configure and test higher
level drivers like the leds-gpio driver and corresponding userspace
before actual hardware is available.

Signed-off-by: Vincent Whitchurch <vincent.whitchurch@xxxxxxxx>
---

Notes:
    v3:
    - Keep includes sorted alphabetically
    - Drop CONFIG_OF ifdefs
    
    v2:
    - Remove most of the added code, since the latest driver doesn't need it.
    - Drop DT binding document, since Rob Herring was OK with not documenting this:
      https://lore.kernel.org/linux-devicetree/5baa1ae6.1c69fb81.847f2.3ab1@xxxxxxxxxxxxx/

 drivers/gpio/gpio-mockup.c | 11 +++++++++--
 1 file changed, 9 insertions(+), 2 deletions(-)

diff --git a/drivers/gpio/gpio-mockup.c b/drivers/gpio/gpio-mockup.c
index 67ed4f238d43..ca87c590ef3f 100644
--- a/drivers/gpio/gpio-mockup.c
+++ b/drivers/gpio/gpio-mockup.c
@@ -16,6 +16,7 @@
 #include <linux/irq_sim.h>
 #include <linux/irqdomain.h>
 #include <linux/module.h>
+#include <linux/of.h>
 #include <linux/platform_device.h>
 #include <linux/property.h>
 #include <linux/slab.h>
@@ -460,9 +461,16 @@ static int gpio_mockup_probe(struct platform_device *pdev)
 	return 0;
 }
 
+static const struct of_device_id gpio_mockup_of_match[] = {
+	{ .compatible = "gpio-mockup", },
+	{},
+};
+MODULE_DEVICE_TABLE(of, gpio_mockup_of_match);
+
 static struct platform_driver gpio_mockup_driver = {
 	.driver = {
 		.name = "gpio-mockup",
+		.of_match_table = of_match_ptr(gpio_mockup_of_match),
 	},
 	.probe = gpio_mockup_probe,
 };
@@ -556,8 +564,7 @@ static int __init gpio_mockup_init(void)
 {
 	int i, num_chips, err;
 
-	if ((gpio_mockup_num_ranges < 2) ||
-	    (gpio_mockup_num_ranges % 2) ||
+	if ((gpio_mockup_num_ranges % 2) ||
 	    (gpio_mockup_num_ranges > GPIO_MOCKUP_MAX_RANGES))
 		return -EINVAL;
 
-- 
2.28.0