[PATCH 15/15] power: reset: at91-reset: handle nrst async for sam9x60

[Claudiu.Beznea]

Handle NRST asynchronously for SAM9X60 to avoid problem with fast drop of
VDDCORE on shutdown operations in the first 100 us after CPU is shutdown.

Signed-off-by: Claudiu Beznea <claudiu.beznea@xxxxxxxxxxxxx>
---
 drivers/power/reset/at91-reset.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/drivers/power/reset/at91-reset.c b/drivers/power/reset/at91-reset.c
index 537ccb180568..3ff9d93a5226 100644
--- a/drivers/power/reset/at91-reset.c
+++ b/drivers/power/reset/at91-reset.c
@@ -35,6 +35,7 @@
 
 #define AT91_RSTC_MR	0x08		/* Reset Controller Mode Register */
 #define AT91_RSTC_URSTEN	BIT(0)		/* User Reset Enable */
+#define AT91_RSTC_URSTASYNC	BIT(2)		/* User Reset Asynchronous Control */
 #define AT91_RSTC_URSTIEN	BIT(4)		/* User Reset Interrupt Enable */
 #define AT91_RSTC_ERSTL		GENMASK(11, 8)	/* External Reset Length */
 
@@ -228,6 +229,13 @@ static int __init at91_reset_probe(struct platform_device *pdev)
 
 	platform_set_drvdata(pdev, reset);
 
+	if (of_device_is_compatible(pdev->dev.of_node, "microchip,sam9x60-rstc")) {
+		u32 val = readl(reset->rstc_base + AT91_RSTC_MR);
+
+		writel(AT91_RSTC_KEY | AT91_RSTC_URSTASYNC | val,
+		       reset->rstc_base + AT91_RSTC_MR);
+	}
+
 	ret = register_restart_handler(&reset->nb);
 	if (ret) {
 		clk_disable_unprepare(reset->sclk);
-- 
2.7.4