[PATCH v2 2/2] hw_random: mxc-rnga: Access data via structure

[Fabio Estevam]

In current driver, everytime we need to access the rng clock (,ie to enable or disable it) a call to clk_get is done.

This is not correct and the preferred way is to provide a rng data structure that could be used for accessing rng resources. 

Cc: Theodore Ts'o <tytso@xxxxxxx>
Cc: Herbert Xu <herbert@xxxxxxxxxxxxxxxxxxx> 
Cc: <linux-kernel@xxxxxxxxxxxxxxx>
Signed-off-by: Fabio Estevam <fabio.estevam@xxxxxxxxxxxxx>
---
Changes since v1:
- No changes. Newly introduced in this version
 drivers/char/hw_random/mxc-rnga.c |  108 +++++++++++++++++-------------------
 1 files changed, 51 insertions(+), 57 deletions(-)

diff --git a/drivers/char/hw_random/mxc-rnga.c b/drivers/char/hw_random/mxc-rnga.c
index 62c7efe..f05d857 100644
--- a/drivers/char/hw_random/mxc-rnga.c
+++ b/drivers/char/hw_random/mxc-rnga.c
@@ -59,16 +59,21 @@
 #define RNGA_STATUS_LAST_READ_STATUS	0x00000002
 #define RNGA_STATUS_SECURITY_VIOLATION	0x00000001
 
-static struct platform_device *rng_dev;
+struct mxc_rng {
+	struct device *dev;
+	struct hwrng rng;
+	void __iomem *mem;
+	struct clk *clk;
+};
 
 static int mxc_rnga_data_present(struct hwrng *rng, int wait)
 {
-	void __iomem *rng_base = (void __iomem *)rng->priv;
 	int i;
+	struct mxc_rng *mxc_rng = container_of(rng, struct mxc_rng, rng);
 
 	for (i = 0; i < 20; i++) {
 		/* how many random numbers are in FIFO? [0-16] */
-		int level = (__raw_readl(rng_base + RNGA_STATUS) &
+		int level = (__raw_readl(mxc_rng->mem + RNGA_STATUS) &
 				RNGA_STATUS_LEVEL_MASK) >> 8;
 		if (level || !wait)
 			return !!level;
@@ -81,20 +86,20 @@ static int mxc_rnga_data_read(struct hwrng *rng, u32 * data)
 {
 	int err;
 	u32 ctrl;
-	void __iomem *rng_base = (void __iomem *)rng->priv;
+	struct mxc_rng *mxc_rng = container_of(rng, struct mxc_rng, rng);
 
 	/* retrieve a random number from FIFO */
-	*data = __raw_readl(rng_base + RNGA_OUTPUT_FIFO);
+	*data = __raw_readl(mxc_rng->mem + RNGA_OUTPUT_FIFO);
 
 	/* some error while reading this random number? */
-	err = __raw_readl(rng_base + RNGA_STATUS) & RNGA_STATUS_ERROR_INT;
+	err = __raw_readl(mxc_rng->mem + RNGA_STATUS) & RNGA_STATUS_ERROR_INT;
 
 	/* if error: clear error interrupt, but doesn't return random number */
 	if (err) {
-		dev_dbg(&rng_dev->dev, "Error while reading random number!\n");
-		ctrl = __raw_readl(rng_base + RNGA_CONTROL);
+		dev_dbg(mxc_rng->dev, "Error while reading random number!\n");
+		ctrl = __raw_readl(mxc_rng->mem + RNGA_CONTROL);
 		__raw_writel(ctrl | RNGA_CONTROL_CLEAR_INT,
-					rng_base + RNGA_CONTROL);
+					mxc_rng->mem + RNGA_CONTROL);
 		return 0;
 	} else
 		return 4;
@@ -103,22 +108,22 @@ static int mxc_rnga_data_read(struct hwrng *rng, u32 * data)
 static int mxc_rnga_init(struct hwrng *rng)
 {
 	u32 ctrl, osc;
-	void __iomem *rng_base = (void __iomem *)rng->priv;
+	struct mxc_rng *mxc_rng = container_of(rng, struct mxc_rng, rng);
 
 	/* wake up */
-	ctrl = __raw_readl(rng_base + RNGA_CONTROL);
-	__raw_writel(ctrl & ~RNGA_CONTROL_SLEEP, rng_base + RNGA_CONTROL);
+	ctrl = __raw_readl(mxc_rng->mem + RNGA_CONTROL);
+	__raw_writel(ctrl & ~RNGA_CONTROL_SLEEP, mxc_rng->mem + RNGA_CONTROL);
 
 	/* verify if oscillator is working */
-	osc = __raw_readl(rng_base + RNGA_STATUS);
+	osc = __raw_readl(mxc_rng->mem + RNGA_STATUS);
 	if (osc & RNGA_STATUS_OSC_DEAD) {
-		dev_err(&rng_dev->dev, "RNGA Oscillator is dead!\n");
+		dev_err(mxc_rng->dev, "RNGA Oscillator is dead!\n");
 		return -ENODEV;
 	}
 
 	/* go running */
-	ctrl = __raw_readl(rng_base + RNGA_CONTROL);
-	__raw_writel(ctrl | RNGA_CONTROL_GO, rng_base + RNGA_CONTROL);
+	ctrl = __raw_readl(mxc_rng->mem + RNGA_CONTROL);
+	__raw_writel(ctrl | RNGA_CONTROL_GO, mxc_rng->mem + RNGA_CONTROL);
 
 	return 0;
 }
@@ -126,40 +131,40 @@ static int mxc_rnga_init(struct hwrng *rng)
 static void mxc_rnga_cleanup(struct hwrng *rng)
 {
 	u32 ctrl;
-	void __iomem *rng_base = (void __iomem *)rng->priv;
+	struct mxc_rng *mxc_rng = container_of(rng, struct mxc_rng, rng);
 
-	ctrl = __raw_readl(rng_base + RNGA_CONTROL);
+	ctrl = __raw_readl(mxc_rng->mem + RNGA_CONTROL);
 
 	/* stop rnga */
-	__raw_writel(ctrl & ~RNGA_CONTROL_GO, rng_base + RNGA_CONTROL);
+	__raw_writel(ctrl & ~RNGA_CONTROL_GO, mxc_rng->mem + RNGA_CONTROL);
 }
 
-static struct hwrng mxc_rnga = {
-	.name = "mxc-rnga",
-	.init = mxc_rnga_init,
-	.cleanup = mxc_rnga_cleanup,
-	.data_present = mxc_rnga_data_present,
-	.data_read = mxc_rnga_data_read
-};
-
 static int __init mxc_rnga_probe(struct platform_device *pdev)
 {
 	int err = -ENODEV;
-	struct clk *clk;
 	struct resource *res, *mem;
-	void __iomem *rng_base = NULL;
-
-	if (rng_dev)
-		return -EBUSY;
-
-	clk = clk_get(&pdev->dev, NULL);
-	if (IS_ERR(clk)) {
+	struct mxc_rng *mxc_rng;
+
+	mxc_rng = devm_kzalloc(&pdev->dev, sizeof(struct mxc_rng),
+					GFP_KERNEL);
+	if (!mxc_rng)
+		return -ENOMEM;
+
+	mxc_rng->dev = &pdev->dev;
+	mxc_rng->rng.name = "mxc-rnga";
+	mxc_rng->rng.init = mxc_rnga_init;
+	mxc_rng->rng.cleanup = mxc_rnga_cleanup,
+	mxc_rng->rng.data_present = mxc_rnga_data_present,
+	mxc_rng->rng.data_read = mxc_rnga_data_read,
+
+	mxc_rng->clk = devm_clk_get(&pdev->dev, NULL);
+	if (IS_ERR(mxc_rng->clk)) {
 		dev_err(&pdev->dev, "Could not get rng_clk!\n");
-		err = PTR_ERR(clk);
+		err = PTR_ERR(mxc_rng->clk);
 		goto out;
 	}
 
-	clk_prepare_enable(clk);
+	clk_prepare_enable(mxc_rng->clk);
 
 	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 	if (!res) {
@@ -173,36 +178,27 @@ static int __init mxc_rnga_probe(struct platform_device *pdev)
 		goto err_region;
 	}
 
-	rng_base = ioremap(res->start, resource_size(res));
-	if (!rng_base) {
+	mxc_rng->mem = ioremap(res->start, resource_size(res));
+	if (!mxc_rng->mem) {
 		err = -ENOMEM;
 		goto err_ioremap;
 	}
 
-	mxc_rnga.priv = (unsigned long)rng_base;
-
-	err = hwrng_register(&mxc_rnga);
+	err = hwrng_register(&mxc_rng->rng);
 	if (err) {
 		dev_err(&pdev->dev, "MXC RNGA registering failed (%d)\n", err);
-		goto err_register;
+		goto err_ioremap;
 	}
 
-	rng_dev = pdev;
-
 	dev_info(&pdev->dev, "MXC RNGA Registered.\n");
 
 	return 0;
 
-err_register:
-	iounmap(rng_base);
-	rng_base = NULL;
-
 err_ioremap:
 	release_mem_region(res->start, resource_size(res));
 
 err_region:
-	clk_disable_unprepare(clk);
-	clk_put(clk);
+	clk_disable_unprepare(mxc_rng->clk);
 
 out:
 	return err;
@@ -211,17 +207,15 @@ out:
 static int __exit mxc_rnga_remove(struct platform_device *pdev)
 {
 	struct resource *res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
-	void __iomem *rng_base = (void __iomem *)mxc_rnga.priv;
-	struct clk *clk = clk_get(&pdev->dev, NULL);
+	struct mxc_rng *mxc_rng = platform_get_drvdata(pdev);
 
-	hwrng_unregister(&mxc_rnga);
+	hwrng_unregister(&mxc_rng->rng);
 
-	iounmap(rng_base);
+	iounmap(mxc_rng->mem);
 
 	release_mem_region(res->start, resource_size(res));
 
-	clk_disable_unprepare(clk);
-	clk_put(clk);
+	clk_disable_unprepare(mxc_rng->clk);
 
 	return 0;
 }
-- 
1.7.1


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