watchdog: max63xx_wdt: Add device tree probing

This adds device tree probing to the MAX63xx driver so it can be
instantiated from the device tree. We use the generic fwnode-based
method to get to the match data and clean up by constifying the
functions as the match is indeed a const.

Cc: Marc Zyngier <maz@kernel.org>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Link: https://lore.kernel.org/r/20210714153314.1004147-2-linus.walleij@linaro.org
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Wim Van Sebroeck <wim@linux-watchdog.org>

drivers/watchdog/max63xx_wdt.c

@@ -26,6 +26,7 @@
 #include <linux/spinlock.h>
 #include <linux/io.h>
 #include <linux/slab.h>
+#include <linux/property.h>
 
 #define DEFAULT_HEARTBEAT 60
 #define MAX_HEARTBEAT     60
@@ -99,8 +100,8 @@ static const struct max63xx_timeout max6373_table[] = {
 	{ },
 };
 
-static struct max63xx_timeout *
-max63xx_select_timeout(struct max63xx_timeout *table, int value)
+static const struct max63xx_timeout *
+max63xx_select_timeout(const struct max63xx_timeout *table, int value)
 {
 	while (table->twd) {
 		if (value <= table->twd) {
@@ -202,14 +203,17 @@ static int max63xx_wdt_probe(struct platform_device *pdev)
 {
 	struct device *dev = &pdev->dev;
 	struct max63xx_wdt *wdt;
-	struct max63xx_timeout *table;
+	const struct max63xx_timeout *table;
 	int err;
 
 	wdt = devm_kzalloc(dev, sizeof(*wdt), GFP_KERNEL);
 	if (!wdt)
 		return -ENOMEM;
 
-	table = (struct max63xx_timeout *)pdev->id_entry->driver_data;
+	/* Attempt to use fwnode first */
+	table = device_get_match_data(dev);
+	if (!table)
+		table = (struct max63xx_timeout *)pdev->id_entry->driver_data;
 
 	if (heartbeat < 1 || heartbeat > MAX_HEARTBEAT)
 		heartbeat = DEFAULT_HEARTBEAT;
@@ -255,11 +259,23 @@ static const struct platform_device_id max63xx_id_table[] = {
 };
 MODULE_DEVICE_TABLE(platform, max63xx_id_table);
 
+static const struct of_device_id max63xx_dt_id_table[] = {
+	{ .compatible = "maxim,max6369", .data = max6369_table, },
+	{ .compatible = "maxim,max6370", .data = max6369_table, },
+	{ .compatible = "maxim,max6371", .data = max6371_table, },
+	{ .compatible = "maxim,max6372", .data = max6371_table, },
+	{ .compatible = "maxim,max6373", .data = max6373_table, },
+	{ .compatible = "maxim,max6374", .data = max6373_table, },
+	{ }
+};
+MODULE_DEVICE_TABLE(of, max63xx_dt_id_table);
+
 static struct platform_driver max63xx_wdt_driver = {
 	.probe		= max63xx_wdt_probe,
 	.id_table	= max63xx_id_table,
 	.driver		= {
 		.name	= "max63xx_wdt",
+		.of_match_table = max63xx_dt_id_table,
 	},
 };