clocksource/drivers/renesas-ostm: Add RZ/G2L OSTM support

RZ/G2L SoC has Generic Timer Module(a.k.a OSTM) which needs to
deassert the reset line before accessing any registers.

This patch adds an entry point for RZ/G2L so that we can deassert
the reset line in probe callback.

Signed-off-by: Biju Das <[email protected]>
Reviewed-by: Lad Prabhakar <[email protected]>
Reviewed-by: Geert Uytterhoeven <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Daniel Lezcano <[email protected]>

Author: bijudas

drivers/clocksource/renesas-ostm.c

@@ -9,6 +9,8 @@
 #include <linux/clk.h>
 #include <linux/clockchips.h>
 #include <linux/interrupt.h>
+#include <linux/platform_device.h>
+#include <linux/reset.h>
 #include <linux/sched_clock.h>
 #include <linux/slab.h>
 
@@ -159,13 +161,22 @@ static int __init ostm_init_clkevt(struct timer_of *to)
 
 static int __init ostm_init(struct device_node *np)
 {
+	struct reset_control *rstc;
 	struct timer_of *to;
 	int ret;
 
 	to = kzalloc(sizeof(*to), GFP_KERNEL);
 	if (!to)
 		return -ENOMEM;
 
+	rstc = of_reset_control_get_optional_exclusive(np, NULL);
+	if (IS_ERR(rstc)) {
+		ret = PTR_ERR(rstc);
+		goto err_free;
+	}
+
+	reset_control_deassert(rstc);
+
 	to->flags = TIMER_OF_BASE | TIMER_OF_CLOCK;
 	if (system_clock) {
 		/*
@@ -178,7 +189,7 @@ static int __init ostm_init(struct device_node *np)
 
 	ret = timer_of_init(np, to);
 	if (ret)
-		goto err_free;
+		goto err_reset;
 
 	/*
 	 * First probed device will be used as system clocksource. Any
@@ -203,9 +214,35 @@ static int __init ostm_init(struct device_node *np)
 
 err_cleanup:
 	timer_of_cleanup(to);
+err_reset:
+	reset_control_assert(rstc);
+	reset_control_put(rstc);
 err_free:
 	kfree(to);
 	return ret;
 }
 
 TIMER_OF_DECLARE(ostm, "renesas,ostm", ostm_init);
+
+#ifdef CONFIG_ARCH_R9A07G044
+static int __init ostm_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+
+	return ostm_init(dev->of_node);
+}
+
+static const struct of_device_id ostm_of_table[] = {
+	{ .compatible = "renesas,ostm", },
+	{ /* sentinel */ }
+};
+
+static struct platform_driver ostm_device_driver = {
+	.driver = {
+		.name = "renesas_ostm",
+		.of_match_table = of_match_ptr(ostm_of_table),
+		.suppress_bind_attrs = true,
+	},
+};
+builtin_platform_driver_probe(ostm_device_driver, ostm_probe);
+#endif