i.MX31: Add hw-random for RNGA

This hw-random driver add support to RNGA hardware found
on some i.MX processors.
Signed-off-by: Alan Carvalho de Assis <acassis@gmail.com>
Acked-by: Matt Mackall <mpm@selenic.com>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

arch/arm/mach-mx3/Kconfig

 if ARCH_MX3
 
 config ARCH_MX31
+	select ARCH_HAS_RNGA
 	bool
 
 config ARCH_MX35

arch/arm/mach-mx3/devices.c

@@ -23,6 +23,7 @@
 #include <linux/gpio.h>
 #include <mach/hardware.h>
 #include <mach/irqs.h>
+#include <mach/common.h>
 #include <mach/imx-uart.h>
 
 #include "devices.h"
@@ -283,6 +284,21 @@ struct platform_device mxcsdhc_device1 = {
 	.num_resources = ARRAY_SIZE(mxcsdhc1_resources),
 	.resource = mxcsdhc1_resources,
 };
+
+static struct resource rnga_resources[] = {
+	{
+		.start = RNGA_BASE_ADDR,
+		.end = RNGA_BASE_ADDR + 0x28,
+		.flags = IORESOURCE_MEM,
+	},
+};
+
+struct platform_device mxc_rnga_device = {
+	.name = "mxc_rnga",
+	.id = -1,
+	.num_resources = 1,
+	.resource = rnga_resources,
+};
 #endif /* CONFIG_ARCH_MX31 */
 
 /* i.MX31 Image Processing Unit */
@@ -359,6 +375,7 @@ static int mx3_devices_init(void)
 	if (cpu_is_mx31()) {
 		mxc_nand_resources[0].start = MX31_NFC_BASE_ADDR;
 		mxc_nand_resources[0].end = MX31_NFC_BASE_ADDR + 0xfff;
+		mxc_register_device(&mxc_rnga_device, NULL);
 	}
 	if (cpu_is_mx35()) {
 		mxc_nand_resources[0].start = MX35_NFC_BASE_ADDR;

arch/arm/plat-mxc/Kconfig

@@ -52,6 +52,10 @@ config MXC_PWM
 	help
 	  Enable support for the i.MX PWM controller(s).
 
+config ARCH_HAS_RNGA
+	bool
+	depends on ARCH_MXC
+
 config ARCH_MXC_IOMUX_V3
 	bool
 endif

drivers/char/hw_random/Kconfig

@@ -148,3 +148,15 @@ config HW_RANDOM_VIRTIO
 
 	  To compile this driver as a module, choose M here: the
 	  module will be called virtio-rng.  If unsure, say N.
+
+config HW_RANDOM_MXC_RNGA
+	tristate "Freescale i.MX RNGA Random Number Generator"
+	depends on HW_RANDOM && ARCH_HAS_RNGA
+	---help---
+	  This driver provides kernel-side support for the Random Number
+	  Generator hardware found on Freescale i.MX processors.
+
+	  To compile this driver as a module, choose M here: the
+	  module will be called mxc-rnga.
+
+	  If unsure, say Y.

drivers/char/hw_random/Makefile

@@ -15,3 +15,4 @@ obj-$(CONFIG_HW_RANDOM_IXP4XX) += ixp4xx-rng.o
 obj-$(CONFIG_HW_RANDOM_OMAP) += omap-rng.o
 obj-$(CONFIG_HW_RANDOM_PASEMI) += pasemi-rng.o
 obj-$(CONFIG_HW_RANDOM_VIRTIO) += virtio-rng.o
+obj-$(CONFIG_HW_RANDOM_MXC_RNGA) += mxc-rnga.o

drivers/char/hw_random/mxc-rnga.c

+/*
+ * RNG driver for Freescale RNGA
+ *
+ * Copyright 2008-2009 Freescale Semiconductor, Inc. All Rights Reserved.
+ * Author: Alan Carvalho de Assis <acassis@gmail.com>
+ */
+
+/*
+ * The code contained herein is licensed under the GNU General Public
+ * License. You may obtain a copy of the GNU General Public License
+ * Version 2 or later at the following locations:
+ *
+ * http://www.opensource.org/licenses/gpl-license.html
+ * http://www.gnu.org/copyleft/gpl.html
+ *
+ * This driver is based on other RNG drivers.
+ */
+
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/kernel.h>
+#include <linux/clk.h>
+#include <linux/err.h>
+#include <linux/ioport.h>
+#include <linux/platform_device.h>
+#include <linux/hw_random.h>
+#include <linux/io.h>
+
+/* RNGA Registers */
+#define RNGA_CONTROL			0x00
+#define RNGA_STATUS			0x04
+#define RNGA_ENTROPY			0x08
+#define RNGA_OUTPUT_FIFO		0x0c
+#define RNGA_MODE			0x10
+#define RNGA_VERIFICATION_CONTROL	0x14
+#define RNGA_OSC_CONTROL_COUNTER	0x18
+#define RNGA_OSC1_COUNTER		0x1c
+#define RNGA_OSC2_COUNTER		0x20
+#define RNGA_OSC_COUNTER_STATUS		0x24
+
+/* RNGA Registers Range */
+#define RNG_ADDR_RANGE			0x28
+
+/* RNGA Control Register */
+#define RNGA_CONTROL_SLEEP		0x00000010
+#define RNGA_CONTROL_CLEAR_INT		0x00000008
+#define RNGA_CONTROL_MASK_INTS		0x00000004
+#define RNGA_CONTROL_HIGH_ASSURANCE	0x00000002
+#define RNGA_CONTROL_GO			0x00000001
+
+#define RNGA_STATUS_LEVEL_MASK		0x0000ff00
+
+/* RNGA Status Register */
+#define RNGA_STATUS_OSC_DEAD		0x80000000
+#define RNGA_STATUS_SLEEP		0x00000010
+#define RNGA_STATUS_ERROR_INT		0x00000008
+#define RNGA_STATUS_FIFO_UNDERFLOW	0x00000004
+#define RNGA_STATUS_LAST_READ_STATUS	0x00000002
+#define RNGA_STATUS_SECURITY_VIOLATION	0x00000001
+
+static struct platform_device *rng_dev;
+
+static int mxc_rnga_data_present(struct hwrng *rng)
+{
+	int level;
+	void __iomem *rng_base = (void __iomem *)rng->priv;
+
+	/* how many random numbers is in FIFO? [0-16] */
+	level = ((__raw_readl(rng_base + RNGA_STATUS) &
+			RNGA_STATUS_LEVEL_MASK) >> 8);
+
+	return level > 0 ? 1 : 0;
+}
+
+static int mxc_rnga_data_read(struct hwrng *rng, u32 * data)
+{
+	int err;
+	u32 ctrl;
+	void __iomem *rng_base = (void __iomem *)rng->priv;
+
+	/* retrieve a random number from FIFO */
+	*data = __raw_readl(rng_base + RNGA_OUTPUT_FIFO);
+
+	/* some error while reading this random number? */
+	err = __raw_readl(rng_base + 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);
+		__raw_writel(ctrl | RNGA_CONTROL_CLEAR_INT,
+					rng_base + RNGA_CONTROL);
+		return 0;
+	} else
+		return 4;
+}
+
+static int mxc_rnga_init(struct hwrng *rng)
+{
+	u32 ctrl, osc;
+	void __iomem *rng_base = (void __iomem *)rng->priv;
+
+	/* wake up */
+	ctrl = __raw_readl(rng_base + RNGA_CONTROL);
+	__raw_writel(ctrl & ~RNGA_CONTROL_SLEEP, rng_base + RNGA_CONTROL);
+
+	/* verify if oscillator is working */
+	osc = __raw_readl(rng_base + RNGA_STATUS);
+	if (osc & RNGA_STATUS_OSC_DEAD) {
+		dev_err(&rng_dev->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);
+
+	return 0;
+}
+
+static void mxc_rnga_cleanup(struct hwrng *rng)
+{
+	u32 ctrl;
+	void __iomem *rng_base = (void __iomem *)rng->priv;
+
+	ctrl = __raw_readl(rng_base + RNGA_CONTROL);
+
+	/* stop rnga */
+	__raw_writel(ctrl & ~RNGA_CONTROL_GO, rng_base + 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, "rng");
+	if (IS_ERR(clk)) {
+		dev_err(&pdev->dev, "Could not get rng_clk!\n");
+		err = PTR_ERR(clk);
+		goto out;
+	}
+
+	clk_enable(clk);
+
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	if (!res) {
+		err = -ENOENT;
+		goto err_region;
+	}
+
+	mem = request_mem_region(res->start, resource_size(res), pdev->name);
+	if (mem == NULL) {
+		err = -EBUSY;
+		goto err_region;
+	}
+
+	rng_base = ioremap(res->start, resource_size(res));
+	if (!rng_base) {
+		err = -ENOMEM;
+		goto err_ioremap;
+	}
+
+	mxc_rnga.priv = (unsigned long)rng_base;
+
+	err = hwrng_register(&mxc_rnga);
+	if (err) {
+		dev_err(&pdev->dev, "MXC RNGA registering failed (%d)\n", err);
+		goto err_register;
+	}
+
+	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(clk);
+	clk_put(clk);
+
+out:
+	return err;
+}
+
+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, "rng");
+
+	hwrng_unregister(&mxc_rnga);
+
+	iounmap(rng_base);
+
+	release_mem_region(res->start, resource_size(res));
+
+	clk_disable(clk);
+	clk_put(clk);
+
+	return 0;
+}
+
+static struct platform_driver mxc_rnga_driver = {
+	.driver = {
+		   .name = "mxc_rnga",
+		   .owner = THIS_MODULE,
+		   },
+	.remove = __exit_p(mxc_rnga_remove),
+};
+
+static int __init mod_init(void)
+{
+	return platform_driver_probe(&mxc_rnga_driver, mxc_rnga_probe);
+}
+
+static void __exit mod_exit(void)
+{
+	platform_driver_unregister(&mxc_rnga_driver);
+}
+
+module_init(mod_init);
+module_exit(mod_exit);
+
+MODULE_AUTHOR("Freescale Semiconductor, Inc.");
+MODULE_DESCRIPTION("H/W RNGA driver for i.MX");
+MODULE_LICENSE("GPL");