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 <jacmet@sunsite.dk>
Reviewed-by: Jamie Iles <jamie@jamieiles.com>
Acked-by: Nicolas Ferre <nicolas.ferre@atmel.com>
Acked-by: Herbert Xu <herbert@gondor.apana.org.au>

3 files changed, 172 insertions, 0 deletions

diff --git a/drivers/char/hw_random/Kconfig b/drivers/char/hw_random/Kconfig
index 1d2ebc7a4947..e0135873ba9d 100644
--- a/drivers/char/hw_random/Kconfig
+++ b/drivers/char/hw_random/Kconfig
@@ -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
diff --git a/drivers/char/hw_random/Makefile b/drivers/char/hw_random/Makefile
index c88f244c8a71..b2ff5265a996 100644
--- a/drivers/char/hw_random/Makefile
+++ b/drivers/char/hw_random/Makefile
@@ -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
diff --git a/drivers/char/hw_random/atmel-rng.c b/drivers/char/hw_random/atmel-rng.c
new file mode 100644
index 000000000000..241df2e76aba
--- /dev/null
+++ b/drivers/char/hw_random/atmel-rng.c
@@ -0,0 +1,158 @@
+/*
+ * Copyright (c) 2011 Peter Korsgaard <jacmet@sunsite.dk>
+ *
+ * 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);
+
+static void __exit atmel_trng_exit(void)
+{
+        platform_driver_unregister(&atmel_trng_driver);
+}
+module_exit(atmel_trng_exit);
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Peter Korsgaard <jacmet@sunsite.dk>");
+MODULE_DESCRIPTION("Atmel true random number generator driver");