linux-kernel - [PATCH v2 5/5] hwrng: imx-rngc - simplify interrupt mask/unmask

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Date:   Thu,  5 Mar 2020 21:58:24 +0100
From:   Martin Kaiser <martin@...ser.cx>
To:     Herbert Xu <herbert@...dor.apana.org.au>,
        PrasannaKumar Muralidharan <prasannatsmkumar@...il.com>,
        NXP Linux Team <linux-imx@....com>
Cc:     linux-crypto@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        linux-kernel@...r.kernel.org, Martin Kaiser <martin@...ser.cx>
Subject: [PATCH v2 5/5] hwrng: imx-rngc - simplify interrupt mask/unmask

Use a simpler approach for masking / unmasking the rngc interrupt:
The interrupt is unmasked while self-test is running and when the rngc
driver is used by the hwrng core.

Mask the interrupt again when self test is finished, regardless of
self test success or failure.

Unmask the interrupt in the init function. Add a cleanup function where
the rngc interrupt is masked again.

Signed-off-by: Martin Kaiser <martin@...ser.cx>
---
 drivers/char/hw_random/imx-rngc.c | 43 ++++++++++++++++++++-----------
 1 file changed, 28 insertions(+), 15 deletions(-)

diff --git a/drivers/char/hw_random/imx-rngc.c b/drivers/char/hw_random/imx-rngc.c
index 50a8923d829a..9c47e431ce90 100644
--- a/drivers/char/hw_random/imx-rngc.c
+++ b/drivers/char/hw_random/imx-rngc.c
@@ -111,17 +111,11 @@ static int imx_rngc_self_test(struct imx_rngc *rngc)
 	writel(cmd | RNGC_CMD_SELF_TEST, rngc->base + RNGC_COMMAND);
 
 	ret = wait_for_completion_timeout(&rngc->rng_op_done, RNGC_TIMEOUT);
-	if (!ret) {
-		imx_rngc_irq_mask_clear(rngc);
+	imx_rngc_irq_mask_clear(rngc);
+	if (!ret)
 		return -ETIMEDOUT;
-	}
-
-	if (rngc->err_reg != 0) {
-		imx_rngc_irq_mask_clear(rngc);
-		return -EIO;
-	}
 
-	return 0;
+	return rngc->err_reg ? -EIO : 0;
 }
 
 static int imx_rngc_read(struct hwrng *rng, void *data, size_t max, bool wait)
@@ -185,10 +179,10 @@ static int imx_rngc_init(struct hwrng *rng)
 	cmd = readl(rngc->base + RNGC_COMMAND);
 	writel(cmd | RNGC_CMD_CLR_ERR, rngc->base + RNGC_COMMAND);
 
+	imx_rngc_irq_unmask(rngc);
+
 	/* create seed, repeat while there is some statistical error */
 	do {
-		imx_rngc_irq_unmask(rngc);
-
 		/* seed creation */
 		cmd = readl(rngc->base + RNGC_COMMAND);
 		writel(cmd | RNGC_CMD_SEED, rngc->base + RNGC_COMMAND);
@@ -197,14 +191,16 @@ static int imx_rngc_init(struct hwrng *rng)
 				RNGC_TIMEOUT);
 
 		if (!ret) {
-			imx_rngc_irq_mask_clear(rngc);
-			return -ETIMEDOUT;
+			ret = -ETIMEDOUT;
+			goto err;
 		}
 
 	} while (rngc->err_reg == RNGC_ERROR_STATUS_STAT_ERR);
 
-	if (rngc->err_reg)
-		return -EIO;
+	if (rngc->err_reg) {
+		ret = -EIO;
+		goto err;
+	}
 
 	/*
 	 * enable automatic seeding, the rngc creates a new seed automatically
@@ -214,7 +210,23 @@ static int imx_rngc_init(struct hwrng *rng)
 	ctrl |= RNGC_CTRL_AUTO_SEED;
 	writel(ctrl, rngc->base + RNGC_CONTROL);
 
+	/*
+	 * if initialisation was successful, we keep the interrupt
+	 * unmasked until imx_rngc_cleanup is called
+	 * we mask the interrupt ourselves if we return an error
+	 */
 	return 0;
+
+err:
+	imx_rngc_irq_mask_clear(rngc);
+	return ret;
+}
+
+static void imx_rngc_cleanup(struct hwrng *rng)
+{
+	struct imx_rngc *rngc = container_of(rng, struct imx_rngc, rng);
+
+	imx_rngc_irq_mask_clear(rngc);
 }
 
 static int imx_rngc_probe(struct platform_device *pdev)
@@ -272,6 +284,7 @@ static int imx_rngc_probe(struct platform_device *pdev)
 	rngc->rng.name = pdev->name;
 	rngc->rng.init = imx_rngc_init;
 	rngc->rng.read = imx_rngc_read;
+	rngc->rng.cleanup = imx_rngc_cleanup;
 
 	rngc->dev = &pdev->dev;
 	platform_set_drvdata(pdev, rngc);
-- 
2.20.1