From 57f0f512b273f60d52568b8c6b77e17f5636edc0 Mon Sep 17 00:00:00 2001
From: André Fabian Silva Delgado <emulatorman@parabola.nu>
Date: Wed, 5 Aug 2015 17:04:01 -0300
Subject: Initial import

---
 drivers/char/hw_random/atmel-rng.c | 148 +++++++++++++++++++++++++++++++++++++
 1 file changed, 148 insertions(+)
 create mode 100644 drivers/char/hw_random/atmel-rng.c

(limited to 'drivers/char/hw_random/atmel-rng.c')

diff --git a/drivers/char/hw_random/atmel-rng.c b/drivers/char/hw_random/atmel-rng.c
new file mode 100644
index 000000000..0fcc9e69a
--- /dev/null
+++ b/drivers/char/hw_random/atmel-rng.c
@@ -0,0 +1,148 @@
+/*
+ * 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_ISR) & 1) {
+		*data = readl(trng->base + TRNG_ODATA);
+		/*
+		  ensure data ready is only set again AFTER the next data
+		  word is ready in case it got set between checking ISR
+		  and reading ODATA, so we don't risk re-reading the
+		  same word
+		*/
+		readl(trng->base + TRNG_ISR);
+		return 4;
+	} else
+		return 0;
+}
+
+static int atmel_trng_probe(struct platform_device *pdev)
+{
+	struct atmel_trng *trng;
+	struct resource *res;
+	int ret;
+
+	trng = devm_kzalloc(&pdev->dev, sizeof(*trng), GFP_KERNEL);
+	if (!trng)
+		return -ENOMEM;
+
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	trng->base = devm_ioremap_resource(&pdev->dev, res);
+	if (IS_ERR(trng->base))
+		return PTR_ERR(trng->base);
+
+	trng->clk = devm_clk_get(&pdev->dev, NULL);
+	if (IS_ERR(trng->clk))
+		return PTR_ERR(trng->clk);
+
+	ret = clk_prepare_enable(trng->clk);
+	if (ret)
+		return ret;
+
+	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);
+	return ret;
+}
+
+static int 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_unprepare(trng->clk);
+
+	return 0;
+}
+
+#ifdef CONFIG_PM
+static int atmel_trng_suspend(struct device *dev)
+{
+	struct atmel_trng *trng = dev_get_drvdata(dev);
+
+	clk_disable_unprepare(trng->clk);
+
+	return 0;
+}
+
+static int atmel_trng_resume(struct device *dev)
+{
+	struct atmel_trng *trng = dev_get_drvdata(dev);
+
+	return clk_prepare_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 const struct of_device_id atmel_trng_dt_ids[] = {
+	{ .compatible = "atmel,at91sam9g45-trng" },
+	{ /* sentinel */ }
+};
+MODULE_DEVICE_TABLE(of, atmel_trng_dt_ids);
+
+static struct platform_driver atmel_trng_driver = {
+	.probe		= atmel_trng_probe,
+	.remove		= atmel_trng_remove,
+	.driver		= {
+		.name	= "atmel-trng",
+#ifdef CONFIG_PM
+		.pm	= &atmel_trng_pm_ops,
+#endif /* CONFIG_PM */
+		.of_match_table = atmel_trng_dt_ids,
+	},
+};
+
+module_platform_driver(atmel_trng_driver);
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Peter Korsgaard <jacmet@sunsite.dk>");
+MODULE_DESCRIPTION("Atmel true random number generator driver");
-- 
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