[PATCH] rtc: tegra: Add ACPI support

[Kartik Rajput <kkartik@nvidia.com>]

Add ACPI support for Tegra RTC, which is available on Tegra241 and
Tegra410. Both Tegra241 and Tegra410 use the same ACPI ID 'NVDA0280'.
The RTC clock is configured by UEFI before the kernel boots.

Signed-off-by: Kartik Rajput <kkartik@nvidia.com>
---
 drivers/rtc/rtc-tegra.c | 28 ++++++++++++++++++++--------
 1 file changed, 20 insertions(+), 8 deletions(-)

diff --git a/drivers/rtc/rtc-tegra.c b/drivers/rtc/rtc-tegra.c
index 46788db89953..40617c82070f 100644
--- a/drivers/rtc/rtc-tegra.c
+++ b/drivers/rtc/rtc-tegra.c
@@ -5,6 +5,7 @@
  * Copyright (c) 2010-2019, NVIDIA Corporation.
  */
 
+#include <linux/acpi.h>
 #include <linux/clk.h>
 #include <linux/delay.h>
 #include <linux/init.h>
@@ -274,6 +275,12 @@ static const struct of_device_id tegra_rtc_dt_match[] = {
 };
 MODULE_DEVICE_TABLE(of, tegra_rtc_dt_match);
 
+static const struct acpi_device_id tegra_rtc_acpi_match[] = {
+	{ "NVDA0280", 0 },
+	{ }
+};
+MODULE_DEVICE_TABLE(acpi, tegra_rtc_acpi_match);
+
 static int tegra_rtc_probe(struct platform_device *pdev)
 {
 	struct tegra_rtc_info *info;
@@ -300,13 +307,15 @@ static int tegra_rtc_probe(struct platform_device *pdev)
 	info->rtc->ops = &tegra_rtc_ops;
 	info->rtc->range_max = U32_MAX;
 
-	info->clk = devm_clk_get(&pdev->dev, NULL);
-	if (IS_ERR(info->clk))
-		return PTR_ERR(info->clk);
+	if (is_of_node(dev_fwnode(&pdev->dev))) {
+		info->clk = devm_clk_get(&pdev->dev, NULL);
+		if (IS_ERR(info->clk))
+			return PTR_ERR(info->clk);
 
-	ret = clk_prepare_enable(info->clk);
-	if (ret < 0)
-		return ret;
+		ret = clk_prepare_enable(info->clk);
+		if (ret < 0)
+			return ret;
+	}
 
 	/* set context info */
 	info->pdev = pdev;
@@ -338,7 +347,8 @@ static int tegra_rtc_probe(struct platform_device *pdev)
 	return 0;
 
 disable_clk:
-	clk_disable_unprepare(info->clk);
+	if (is_of_node(dev_fwnode(&pdev->dev)))
+		clk_disable_unprepare(info->clk);
 	return ret;
 }
 
@@ -346,7 +356,8 @@ static void tegra_rtc_remove(struct platform_device *pdev)
 {
 	struct tegra_rtc_info *info = platform_get_drvdata(pdev);
 
-	clk_disable_unprepare(info->clk);
+	if (is_of_node(dev_fwnode(&pdev->dev)))
+		clk_disable_unprepare(info->clk);
 }
 
 #ifdef CONFIG_PM_SLEEP
@@ -404,6 +415,7 @@ static struct platform_driver tegra_rtc_driver = {
 	.driver = {
 		.name = "tegra_rtc",
 		.of_match_table = tegra_rtc_dt_match,
+		.acpi_match_table = tegra_rtc_acpi_match,
 		.pm = &tegra_rtc_pm_ops,
 	},
 };
-- 
2.43.0