[PATCH v3 2/3] 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'.
When ACPI boot is used, the RTC clock is configured by UEFI before
the kernel boots. On device-tree boot, the probe must fail if clocks are
not provided in the device-tree.

Signed-off-by: Kartik Rajput <kkartik@nvidia.com>
---
Changes in v3:
	* Add patch to use devm_clk_get_enabled().
	* Add patch to use pm_sleep_ptr().
	* Update commit message to specify clocks are requried for
	  device-tree boot.
Changes in v2:
	* Dropped "linux/acpi.h" from includes.
	* Dropped redundant ', 0' part from tegra_rtc_acpi_match.
	* Replaced "is_of_node(dev_fwnode(&pdev->dev))" with
	  "dev_of_node(&pdev->dev)" to check device of node.
	* Dropped redundant of_node checks before accessing clock
	  related APIs.
---
 drivers/rtc/rtc-tegra.c | 15 ++++++++++++---
 1 file changed, 12 insertions(+), 3 deletions(-)

diff --git a/drivers/rtc/rtc-tegra.c b/drivers/rtc/rtc-tegra.c
index 51f5bb55c176..ad0c57ce87df 100644
--- a/drivers/rtc/rtc-tegra.c
+++ b/drivers/rtc/rtc-tegra.c
@@ -274,6 +274,12 @@ 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" },
+	{ }
+};
+MODULE_DEVICE_TABLE(acpi, tegra_rtc_acpi_match);
+
 static int tegra_rtc_probe(struct platform_device *pdev)
 {
 	struct tegra_rtc_info *info;
@@ -300,9 +306,11 @@ 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_enabled(&pdev->dev, NULL);
-	if (IS_ERR(info->clk))
-		return PTR_ERR(info->clk);
+	if (dev_of_node(&pdev->dev)) {
+		info->clk = devm_clk_get_enabled(&pdev->dev, NULL);
+		if (IS_ERR(info->clk))
+			return PTR_ERR(info->clk);
+	}
 
 	/* set context info */
 	info->pdev = pdev;
@@ -394,6 +402,7 @@ 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