[PATCH 7/8] clocksource/drivers/timer-goldfish: Add device tree probing support

[Kuan-Wei Chiu <visitorckw@gmail.com>]

The driver currently only supports board-level initialization via
goldfish_timer_init() on m68k virt.

Register a platform driver matching "google,goldfish-rtc" so device
tree platforms can also probe the timer. Since DT platforms typically
expose a single goldfish-rtc device that cannot be bound by both
drivers at once, depend on M68K || !RTC_DRV_GOLDFISH in Kconfig to
avoid conflicting with rtc-goldfish.

Signed-off-by: Kuan-Wei Chiu <visitorckw@gmail.com>
---
 drivers/clocksource/Kconfig          |  5 +-
 drivers/clocksource/timer-goldfish.c | 93 +++++++++++++++++++++-------
 2 files changed, 74 insertions(+), 24 deletions(-)

diff --git a/drivers/clocksource/Kconfig b/drivers/clocksource/Kconfig
index da83483296d5..3a94feb377a5 100644
--- a/drivers/clocksource/Kconfig
+++ b/drivers/clocksource/Kconfig
@@ -760,8 +760,9 @@ config MICROCHIP_PIT64B
 
 config GOLDFISH_TIMER
 	bool "Clocksource using goldfish-rtc"
-	depends on M68K || COMPILE_TEST
-	depends on RTC_DRV_GOLDFISH
+	depends on M68K || OF || COMPILE_TEST
+	depends on M68K || !RTC_DRV_GOLDFISH
+	depends on HAS_IOMEM
 	help
 	  Support for the timer/counter of goldfish-rtc
 
diff --git a/drivers/clocksource/timer-goldfish.c b/drivers/clocksource/timer-goldfish.c
index 208b80c46193..563390012b89 100644
--- a/drivers/clocksource/timer-goldfish.c
+++ b/drivers/clocksource/timer-goldfish.c
@@ -5,6 +5,8 @@
 #include <linux/clocksource.h>
 #include <linux/clockchips.h>
 #include <linux/module.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
 #include <linux/slab.h>
 #include <linux/spinlock.h>
 #include <linux/goldfish.h>
@@ -102,15 +104,11 @@ static irqreturn_t goldfish_timer_irq(int irq, void *dev_id)
 	return IRQ_HANDLED;
 }
 
-int __init goldfish_timer_init(int irq, void __iomem *base)
+static int goldfish_timer_common_init(struct goldfish_timer *timerdrv,
+				      int irq, void __iomem *base)
 {
-	struct goldfish_timer *timerdrv;
 	int ret;
 
-	timerdrv = kzalloc_obj(*timerdrv);
-	if (!timerdrv)
-		return -ENOMEM;
-
 	timerdrv->base = base;
 	raw_spin_lock_init(&timerdrv->lock);
 
@@ -123,18 +121,6 @@ int __init goldfish_timer_init(int irq, void __iomem *base)
 		.set_next_event		= goldfish_timer_next_event,
 	};
 
-	timerdrv->res = (struct resource){
-		.name  = "goldfish_timer",
-		.start = (unsigned long)base,
-		.end   = (unsigned long)base + 0xfff,
-	};
-
-	ret = request_resource(&iomem_resource, &timerdrv->res);
-	if (ret) {
-		pr_err("Cannot allocate '%s' resource\n", timerdrv->res.name);
-		goto err_free;
-	}
-
 	timerdrv->cs = (struct clocksource){
 		.name		= "goldfish_timer",
 		.rating		= 400,
@@ -146,26 +132,89 @@ int __init goldfish_timer_init(int irq, void __iomem *base)
 	ret = clocksource_register_hz(&timerdrv->cs, NSEC_PER_SEC);
 	if (ret) {
 		pr_err("Couldn't register goldfish-timer clocksource\n");
-		goto err_release_res;
+		return ret;
 	}
 
 	ret = request_irq(irq, goldfish_timer_irq, IRQF_TIMER,
 			  "goldfish_timer", timerdrv);
 	if (ret) {
 		pr_err("Couldn't register goldfish-timer interrupt\n");
-		goto err_unregister_cs;
+		clocksource_unregister(&timerdrv->cs);
+		return ret;
 	}
 
 	clockevents_config_and_register(&timerdrv->ced, NSEC_PER_SEC,
 					1, 0xffffffff);
 
 	return 0;
+}
+
+int __init goldfish_timer_init(int irq, void __iomem *base)
+{
+	struct goldfish_timer *timerdrv;
+	int ret;
+
+	timerdrv = kzalloc_obj(*timerdrv);
+	if (!timerdrv)
+		return -ENOMEM;
+
+	timerdrv->res = (struct resource){
+		.name  = "goldfish_timer",
+		.start = (unsigned long)base,
+		.end   = (unsigned long)base + 0xfff,
+	};
+
+	ret = request_resource(&iomem_resource, &timerdrv->res);
+	if (ret) {
+		pr_err("Cannot allocate '%s' resource\n", timerdrv->res.name);
+		goto err_free;
+	}
+
+	ret = goldfish_timer_common_init(timerdrv, irq, base);
+	if (ret)
+		goto err_release_res;
+
+	return 0;
 
-err_unregister_cs:
-	clocksource_unregister(&timerdrv->cs);
 err_release_res:
 	release_resource(&timerdrv->res);
 err_free:
 	kfree(timerdrv);
 	return ret;
 }
+
+static int goldfish_timer_probe(struct platform_device *pdev)
+{
+	struct goldfish_timer *timerdrv;
+	void __iomem *base;
+	int irq;
+
+	base = devm_platform_ioremap_resource(pdev, 0);
+	if (IS_ERR(base))
+		return PTR_ERR(base);
+
+	irq = platform_get_irq(pdev, 0);
+	if (irq < 0)
+		return irq;
+
+	timerdrv = devm_kzalloc(&pdev->dev, sizeof(*timerdrv), GFP_KERNEL);
+	if (!timerdrv)
+		return -ENOMEM;
+
+	return goldfish_timer_common_init(timerdrv, irq, base);
+}
+
+static const struct of_device_id goldfish_timer_of_match[] = {
+	{ .compatible = "google,goldfish-rtc", },
+	{},
+};
+
+static struct platform_driver goldfish_timer_driver = {
+	.probe = goldfish_timer_probe,
+	.driver = {
+		.name = "goldfish_timer",
+		.of_match_table = goldfish_timer_of_match,
+		.suppress_bind_attrs = true,
+	},
+};
+builtin_platform_driver(goldfish_timer_driver);
-- 
2.56.0.398.g882cbad275-goog