linux-kernel - [PATCH 3/7] hwrng: rockchip: store dev pointer in driver struct

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Message-Id: <20250130-rk3588-trng-submission-v1-3-97ff76568e49@collabora.com>
Date: Thu, 30 Jan 2025 17:31:17 +0100
From: Nicolas Frattaroli <nicolas.frattaroli@...labora.com>
To: Philipp Zabel <p.zabel@...gutronix.de>, Rob Herring <robh@...nel.org>, 
 Krzysztof Kozlowski <krzk+dt@...nel.org>, 
 Conor Dooley <conor+dt@...nel.org>, Heiko Stuebner <heiko@...ech.de>, 
 Olivia Mackall <olivia@...enic.com>, 
 Herbert Xu <herbert@...dor.apana.org.au>, 
 Daniel Golle <daniel@...rotopia.org>, Aurelien Jarno <aurelien@...el32.net>
Cc: Sebastian Reichel <sebastian.reichel@...labora.com>, 
 devicetree@...r.kernel.org, linux-arm-kernel@...ts.infradead.org, 
 linux-rockchip@...ts.infradead.org, linux-kernel@...r.kernel.org, 
 linux-crypto@...r.kernel.org, 
 Nicolas Frattaroli <nicolas.frattaroli@...labora.com>
Subject: [PATCH 3/7] hwrng: rockchip: store dev pointer in driver struct

The rockchip rng driver does a dance to store the dev pointer in the
hwrng's unsigned long "priv" member. However, since the struct hwrng
member of rk_rng is not a pointer, we can use container_of to get the
struct rk_rng instance from just the struct hwrng*, which means we don't
have to subvert what little there is in C of a type system and can
instead store a pointer to the device struct in the rk_rng itself.

Signed-off-by: Nicolas Frattaroli <nicolas.frattaroli@...labora.com>
---
 drivers/char/hw_random/rockchip-rng.c | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/drivers/char/hw_random/rockchip-rng.c b/drivers/char/hw_random/rockchip-rng.c
index 289b385bbf05e3c828b6e26feb2453db62f6b2a2..b1b510087e5862b3b2ed97cefbf10620bcf9b020 100644
--- a/drivers/char/hw_random/rockchip-rng.c
+++ b/drivers/char/hw_random/rockchip-rng.c
@@ -54,6 +54,7 @@ struct rk_rng {
 	void __iomem *base;
 	int clk_num;
 	struct clk_bulk_data *clk_bulks;
+	struct device *dev;
 };
 
 /* The mask in the upper 16 bits determines the bits that are updated */
@@ -70,8 +71,7 @@ static int rk_rng_init(struct hwrng *rng)
 	/* start clocks */
 	ret = clk_bulk_prepare_enable(rk_rng->clk_num, rk_rng->clk_bulks);
 	if (ret < 0) {
-		dev_err((struct device *) rk_rng->rng.priv,
-			"Failed to enable clks %d\n", ret);
+		dev_err(rk_rng->dev, "Failed to enable clocks: %d\n", ret);
 		return ret;
 	}
 
@@ -105,7 +105,7 @@ static int rk_rng_read(struct hwrng *rng, void *buf, size_t max, bool wait)
 	u32 reg;
 	int ret = 0;
 
-	ret = pm_runtime_resume_and_get((struct device *) rk_rng->rng.priv);
+	ret = pm_runtime_resume_and_get(rk_rng->dev);
 	if (ret < 0)
 		return ret;
 
@@ -122,8 +122,8 @@ static int rk_rng_read(struct hwrng *rng, void *buf, size_t max, bool wait)
 	/* Read random data stored in the registers */
 	memcpy_fromio(buf, rk_rng->base + TRNG_RNG_DOUT, to_read);
 out:
-	pm_runtime_mark_last_busy((struct device *) rk_rng->rng.priv);
-	pm_runtime_put_sync_autosuspend((struct device *) rk_rng->rng.priv);
+	pm_runtime_mark_last_busy(rk_rng->dev);
+	pm_runtime_put_sync_autosuspend(rk_rng->dev);
 
 	return (ret < 0) ? ret : to_read;
 }
@@ -164,7 +164,7 @@ static int rk_rng_probe(struct platform_device *pdev)
 		rk_rng->rng.cleanup = rk_rng_cleanup;
 	}
 	rk_rng->rng.read = rk_rng_read;
-	rk_rng->rng.priv = (unsigned long) dev;
+	rk_rng->dev = dev;
 	rk_rng->rng.quality = 900;
 
 	pm_runtime_set_autosuspend_delay(dev, RK_RNG_AUTOSUSPEND_DELAY);

-- 
2.48.1