[PATCH 3/7] rng: stm32: Implement configurable RNG clock error detection

[Gatien Chevallier]

RNG clock error detection is now enabled if the "clock-error-detect"
property is set in the device tree.

Signed-off-by: Gatien Chevallier <gatien.chevallier at foss.st.com>
---
 drivers/rng/stm32_rng.c | 22 +++++++++++++++++-----
 1 file changed, 17 insertions(+), 5 deletions(-)

diff --git a/drivers/rng/stm32_rng.c b/drivers/rng/stm32_rng.c
index 89da78c6c8..ada5d92214 100644
--- a/drivers/rng/stm32_rng.c
+++ b/drivers/rng/stm32_rng.c
@@ -40,6 +40,7 @@ struct stm32_rng_plat {
 	struct clk clk;
 	struct reset_ctl rst;
 	const struct stm32_rng_data *data;
+	bool ced;
 };
 
 static int stm32_rng_read(struct udevice *dev, void *data, size_t len)
@@ -97,25 +98,34 @@ static int stm32_rng_init(struct stm32_rng_plat *pdata)
 
 	cr = readl(pdata->base + RNG_CR);
 
-	/* Disable CED */
-	cr |= RNG_CR_CED;
 	if (pdata->data->has_cond_reset) {
 		cr |= RNG_CR_CONDRST;
+		if (pdata->ced)
+			cr &= ~RNG_CR_CED;
+		else
+			cr |= RNG_CR_CED;
 		writel(cr, pdata->base + RNG_CR);
 		cr &= ~RNG_CR_CONDRST;
+		cr |= RNG_CR_RNGEN;
 		writel(cr, pdata->base + RNG_CR);
 		err = readl_poll_timeout(pdata->base + RNG_CR, cr,
 					 (!(cr & RNG_CR_CONDRST)), 10000);
 		if (err)
 			return err;
+	} else {
+		if (pdata->ced)
+			cr &= ~RNG_CR_CED;
+		else
+			cr |= RNG_CR_CED;
+
+		cr |= RNG_CR_RNGEN;
+
+		writel(cr, pdata->base + RNG_CR);
 	}
 
 	/* clear error indicators */
 	writel(0, pdata->base + RNG_SR);
 
-	cr |= RNG_CR_RNGEN;
-	writel(cr, pdata->base + RNG_CR);
-
 	err = readl_poll_timeout(pdata->base + RNG_SR, sr,
 				 sr & RNG_SR_DRDY, 10000);
 	return err;
@@ -165,6 +175,8 @@ static int stm32_rng_of_to_plat(struct udevice *dev)
 	if (err)
 		return err;
 
+	pdata->ced = dev_read_bool(dev, "clock-error-detect");
+
 	return 0;
 }
 
-- 
2.25.1