linux-kernel - [PATCH v2 2/2] hw_random: timeriomem_rng: Allow setting RNG quality from platform data

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Message-Id: <20170522211224.12202-2-raltherr@google.com>
Date:   Mon, 22 May 2017 14:12:24 -0700
From:   Rick Altherr <raltherr@...gle.com>
To:     linux-crypto@...r.kernel.org
Cc:     linux-kernel@...r.kernel.org, Thomas Gleixner <tglx@...utronix.de>,
        Herbert Xu <herbert@...dor.apana.org.au>,
        Matt Mackall <mpm@...enic.com>
Subject: [PATCH v2 2/2] hw_random: timeriomem_rng: Allow setting RNG quality from platform data

When a hw_random device's quality is non-zero, it will automatically be
used to fill the kernel's entropy pool.  Since timeriomem_rng is used by
many different devices, the quality needs to be provided by platform
data or device tree.

Signed-off-by: Rick Altherr <raltherr@...gle.com>
---

Changes in v2:
- Adjust header comment for platform data quality property to match code
and DT bindings

 drivers/char/hw_random/timeriomem-rng.c | 7 +++++++
 include/linux/timeriomem-rng.h          | 3 +++
 2 files changed, 10 insertions(+)

diff --git a/drivers/char/hw_random/timeriomem-rng.c b/drivers/char/hw_random/timeriomem-rng.c
index a0faa5f05deb..03ff5483d865 100644
--- a/drivers/char/hw_random/timeriomem-rng.c
+++ b/drivers/char/hw_random/timeriomem-rng.c
@@ -151,8 +151,15 @@ static int timeriomem_rng_probe(struct platform_device *pdev)
 			dev_err(&pdev->dev, "missing period\n");
 			return -EINVAL;
 		}
+
+		if (!of_property_read_u32(pdev->dev.of_node,
+						"quality", &i))
+			priv->rng_ops.quality = i;
+		else
+			priv->rng_ops.quality = 0;
 	} else {
 		period = pdata->period;
+		priv->rng_ops.quality = pdata->quality;
 	}
 
 	priv->period = ns_to_ktime(period * NSEC_PER_USEC);
diff --git a/include/linux/timeriomem-rng.h b/include/linux/timeriomem-rng.h
index 46eb27ddbfab..3e00122bcf88 100644
--- a/include/linux/timeriomem-rng.h
+++ b/include/linux/timeriomem-rng.h
@@ -13,4 +13,7 @@ struct timeriomem_rng_data {
 
 	/* measures in usecs */
 	unsigned int		period;
+
+	/* bits of entropy per 1024 bits read */
+	unsigned int		quality;
 };
-- 
2.13.0.303.g4ebf302169-goog