hw_random: add driver for atmel true hardware random number generator

For the IP block on 9g45/9g46/9m10/9m11.

Signed-off-by Peter Korsgaard <[email protected]>

---

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"Baruch" == Baruch Siach <[email protected]> writes:

drivers/char/hw_random/atmel-rng.c line 39

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drivers/char/hw_random/atmel-rng.c new file +10 -0

+static int atmel_trng_read(struct hwrng *rng, void *buf, size_t max,
+			   bool wait)
+{
+	struct atmel_trng *trng = container_of(rng, struct atmel_trng, rng);
+	u32 *data = buf;
+
+	/* data ready? */
+	if (readl(trng->base + TRNG_ODATA) & 1) {
+		*data = readl(trng->base + TRNG_ODATA);
+		return 4;

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drivers/char/hw_random/atmel-rng.c line 39

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"Baruch" == Baruch Siach <[email protected]> writes:

drivers/char/hw_random/atmel-rng.c new file +10 -0

+static int atmel_trng_read(struct hwrng *rng, void *buf, size_t max,
+			   bool wait)
+{
+	struct atmel_trng *trng = container_of(rng, struct atmel_trng, rng);
+	u32 *data = buf;
+
+	/* data ready? */
+	if (readl(trng->base + TRNG_ODATA) & 1) {
+		*data = readl(trng->base + TRNG_ODATA);
+		return 4;

Baruch> Shouldn't you check for max >= 4 before writing to *buf?

Conceptually, yes. The other hw_random drivers don't seem to do it though, and the buffer size is guaranteed to be atleast 32 bytes,

but I can stick a '&& max >= 4' in the conditional if you prefer.

For the IP block on 9g45/9g46/9m10/9m11.

Signed-off-by Peter Korsgaard <[email protected]>

For the IP block on 9g45/9g46/9m10/9m11.

Signed-off-by Peter Korsgaard <[email protected]>

---
Changes since v1:
- Embed struct hwrng in struct atmel_trng as suggested by Jamie Iles.

 drivers/char/hw_random/Kconfig     |   13 +++
 drivers/char/hw_random/Makefile    |    1 +
 drivers/char/hw_random/atmel-rng.c |  158 ++++++++++++++++++++++++++++++++++++
 3 files changed, 172 insertions(+), 0 deletions(-)
 create mode 100644 drivers/char/hw_random/atmel-rng.c

drivers/char/hw_random/Kconfig +13 -0

index 1d2ebc7..e013587 100644
@@ -60,6 +60,19 @@ config HW_RANDOM_AMD
 
 	  If unsure, say Y.
 
+config HW_RANDOM_ATMEL
+	tristate "Atmel Random Number Generator support"
+	depends on HW_RANDOM && ARCH_AT91SAM9G45
+	default HW_RANDOM
+	---help---
+	  This driver provides kernel-side support for the Random Number
+	  Generator hardware found on Atmel AT91 devices.
+
+	  To compile this driver as a module, choose M here: the
+	  module will be called atmel-rng.
+
+	  If unsure, say Y.
+
 config HW_RANDOM_GEODE
 	tristate "AMD Geode HW Random Number Generator support"
 	depends on HW_RANDOM && X86_32 && PCI

drivers/char/hw_random/Makefile +1 -0

index c88f244..b2ff526 100644
@@ -7,6 +7,7 @@ rng-core-y := core.o
 obj-$(CONFIG_HW_RANDOM_TIMERIOMEM) += timeriomem-rng.o
 obj-$(CONFIG_HW_RANDOM_INTEL) += intel-rng.o
 obj-$(CONFIG_HW_RANDOM_AMD) += amd-rng.o
+obj-$(CONFIG_HW_RANDOM_ATMEL) += atmel-rng.o
 obj-$(CONFIG_HW_RANDOM_GEODE) += geode-rng.o
 obj-$(CONFIG_HW_RANDOM_N2RNG) += n2-rng.o
 n2-rng-y := n2-drv.o n2-asm.o

drivers/char/hw_random/atmel-rng.c new file +148 -0

new file mode 100644
index 0000000..241df2e
@@ -0,0 +1,158 @@
+/*
+ * Copyright (c) 2011 Peter Korsgaard <[email protected]>
+ *
+ * This file is licensed under  the terms of the GNU General Public
+ * License version 2. This program is licensed "as is" without any
+ * warranty of any kind, whether express or implied.
+ */
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/slab.h>
+#include <linux/err.h>
+#include <linux/clk.h>
+#include <linux/io.h>
+#include <linux/hw_random.h>
+#include <linux/platform_device.h>
+
+#define TRNG_CR		0x00
+#define TRNG_ISR	0x1c
+#define TRNG_ODATA	0x50
+
+#define TRNG_KEY	0x524e4700 /* RNG */
+
+struct atmel_trng {
+	struct clk *clk;
+	void __iomem *base;
+	struct hwrng rng;
+};
+
+static int atmel_trng_read(struct hwrng *rng, void *buf, size_t max,
+			   bool wait)
+{
+	struct atmel_trng *trng = container_of(rng, struct atmel_trng, rng);
+	u32 *data = buf;
+
+	/* data ready? */
+	if (readl(trng->base + TRNG_ODATA) & 1) {
+		*data = readl(trng->base + TRNG_ODATA);
+		return 4;
+	} else
+		return 0;
+}
+
+static int atmel_trng_probe(struct platform_device *pdev)
+{
+	struct atmel_trng *trng;
+	struct resource *res;
+	int ret;
+
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	if (!res)
+		return -EINVAL;
+
+	trng = devm_kzalloc(&pdev->dev, sizeof(*trng), GFP_KERNEL);
+	if (!trng)
+		return -ENOMEM;
+
+	if (!devm_request_mem_region(&pdev->dev, res->start,
+				     resource_size(res), pdev->name))
+		return -EBUSY;
+
+	trng->base = devm_ioremap(&pdev->dev, res->start, resource_size(res));
+	if (!trng->base)
+		return -EBUSY;
+
+	trng->clk = clk_get(&pdev->dev, NULL);
+	if (IS_ERR(trng->clk))
+		return PTR_ERR(trng->clk);
+
+	ret = clk_enable(trng->clk);
+	if (ret)
+		goto err_enable;
+
+	writel(TRNG_KEY | 1, trng->base + TRNG_CR);
+	trng->rng.name = pdev->name;
+	trng->rng.read = atmel_trng_read;
+
+	ret = hwrng_register(&trng->rng);
+	if (ret)
+		goto err_register;
+
+	platform_set_drvdata(pdev, trng);
+
+	return 0;
+
+err_register:
+	clk_disable(trng->clk);
+err_enable:
+	clk_put(trng->clk);
+
+	return ret;
+}
+
+static int __devexit atmel_trng_remove(struct platform_device *pdev)
+{
+	struct atmel_trng *trng = platform_get_drvdata(pdev);
+
+	hwrng_unregister(&trng->rng);
+
+	writel(TRNG_KEY, trng->base + TRNG_CR);
+	clk_disable(trng->clk);
+	clk_put(trng->clk);
+
+	platform_set_drvdata(pdev, NULL);
+
+	return 0;
+}
+
+#ifdef CONFIG_PM
+static int atmel_trng_suspend(struct device *dev)
+{
+	struct atmel_trng *trng = dev_get_drvdata(dev);
+
+	clk_disable(trng->clk);
+
+	return 0;
+}
+
+static int atmel_trng_resume(struct device *dev)
+{
+	struct atmel_trng *trng = dev_get_drvdata(dev);
+
+	return clk_enable(trng->clk);
+}
+
+static const struct dev_pm_ops atmel_trng_pm_ops = {
+	.suspend	= atmel_trng_suspend,
+	.resume		= atmel_trng_resume,
+};
+#endif /* CONFIG_PM */
+
+static struct platform_driver atmel_trng_driver = {
+	.probe		= atmel_trng_probe,
+	.remove		= __devexit_p(atmel_trng_remove),
+	.driver		= {
+		.name	= "atmel-trng",
+		.owner	= THIS_MODULE,
+#ifdef CONFIG_PM
+		.pm	= &atmel_trng_pm_ops,
+#endif /* CONFIG_PM */
+	},
+};
+
+static int __init atmel_trng_init(void)
+{
+	return platform_driver_register(&atmel_trng_driver);
+}
+module_init(atmel_trng_init);

On 10/06/2011 07:56 PM, Peter Korsgaard :

Quoted 3 lines

For the IP block on 9g45/9g46/9m10/9m11.

Signed-off-by Peter Korsgaard <[email protected]>

Thanks, I am delighted to see this driver!

Acked-by Nicolas Ferre <[email protected]>

Herbert,
I will handle the board specific part but should the driver part go through the Crypto API tree?
Will you expect that I resend the patch with Jamie's and my signatures?