hwrng: OMAP3 ROM Random Number Generator support

This driver provides kernel-side support for the Random Number
Generator hardware found on OMAP34xx processors.

This driver comes from Maemo 2.6.28 kernel and was tested on Nokia RX-51.
It is platform device because it needs board specific function for smc calls.

Signed-off-by: Pali Rohár <[email protected]>
Signed-off-by: Juha Yrjola <[email protected]>
Acked-by: Tony Lindgren <[email protected]>
Signed-off-by: Herbert Xu <[email protected]>

drivers/char/hw_random/Kconfig

@@ -165,6 +165,19 @@ config HW_RANDOM_OMAP
 
  	  If unsure, say Y.
 
+config HW_RANDOM_OMAP3_ROM
+	tristate "OMAP3 ROM Random Number Generator support"
+	depends on HW_RANDOM && ARCH_OMAP3
+	default HW_RANDOM
+	---help---
+	  This driver provides kernel-side support for the Random Number
+	  Generator hardware found on OMAP34xx processors.
+
+	  To compile this driver as a module, choose M here: the
+	  module will be called omap3-rom-rng.
+
+	  If unsure, say Y.
+
 config HW_RANDOM_OCTEON
 	tristate "Octeon Random Number Generator support"
 	depends on HW_RANDOM && CAVIUM_OCTEON_SOC

drivers/char/hw_random/Makefile

@@ -15,6 +15,7 @@ n2-rng-y := n2-drv.o n2-asm.o
 obj-$(CONFIG_HW_RANDOM_VIA) += via-rng.o
 obj-$(CONFIG_HW_RANDOM_IXP4XX) += ixp4xx-rng.o
 obj-$(CONFIG_HW_RANDOM_OMAP) += omap-rng.o
+obj-$(CONFIG_HW_RANDOM_OMAP3_ROM) += omap3-rom-rng.o
 obj-$(CONFIG_HW_RANDOM_PASEMI) += pasemi-rng.o
 obj-$(CONFIG_HW_RANDOM_VIRTIO) += virtio-rng.o
 obj-$(CONFIG_HW_RANDOM_TX4939) += tx4939-rng.o

drivers/char/hw_random/omap3-rom-rng.c

@@ -0,0 +1,141 @@
+/*
+ * omap3-rom-rng.c - RNG driver for TI OMAP3 CPU family
+ *
+ * Copyright (C) 2009 Nokia Corporation
+ * Author: Juha Yrjola <[email protected]>
+ *
+ * Copyright (C) 2013 Pali Rohár <[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.
+ */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/random.h>
+#include <linux/hw_random.h>
+#include <linux/timer.h>
+#include <linux/clk.h>
+#include <linux/err.h>
+#include <linux/platform_device.h>
+
+#define RNG_RESET			0x01
+#define RNG_GEN_PRNG_HW_INIT		0x02
+#define RNG_GEN_HW			0x08
+
+/* param1: ptr, param2: count, param3: flag */
+static u32 (*omap3_rom_rng_call)(u32, u32, u32);
+
+static struct timer_list idle_timer;
+static int rng_idle;
+static struct clk *rng_clk;
+
+static void omap3_rom_rng_idle(unsigned long data)
+{
+	int r;
+
+	r = omap3_rom_rng_call(0, 0, RNG_RESET);
+	if (r != 0) {
+		pr_err("reset failed: %d\n", r);
+		return;
+	}
+	clk_disable_unprepare(rng_clk);
+	rng_idle = 1;
+}
+
+static int omap3_rom_rng_get_random(void *buf, unsigned int count)
+{
+	u32 r;
+	u32 ptr;
+
+	del_timer_sync(&idle_timer);
+	if (rng_idle) {
+		clk_prepare_enable(rng_clk);
+		r = omap3_rom_rng_call(0, 0, RNG_GEN_PRNG_HW_INIT);
+		if (r != 0) {
+			clk_disable_unprepare(rng_clk);
+			pr_err("HW init failed: %d\n", r);
+			return -EIO;
+		}
+		rng_idle = 0;
+	}
+
+	ptr = virt_to_phys(buf);
+	r = omap3_rom_rng_call(ptr, count, RNG_GEN_HW);
+	mod_timer(&idle_timer, jiffies + msecs_to_jiffies(500));
+	if (r != 0)
+		return -EINVAL;
+	return 0;
+}
+
+static int omap3_rom_rng_data_present(struct hwrng *rng, int wait)
+{
+	return 1;
+}
+
+static int omap3_rom_rng_data_read(struct hwrng *rng, u32 *data)
+{
+	int r;
+
+	r = omap3_rom_rng_get_random(data, 4);
+	if (r < 0)
+		return r;
+	return 4;
+}
+
+static struct hwrng omap3_rom_rng_ops = {
+	.name		= "omap3-rom",
+	.data_present	= omap3_rom_rng_data_present,
+	.data_read	= omap3_rom_rng_data_read,
+};
+
+static int omap3_rom_rng_probe(struct platform_device *pdev)
+{
+	pr_info("initializing\n");
+
+	omap3_rom_rng_call = pdev->dev.platform_data;
+	if (!omap3_rom_rng_call) {
+		pr_err("omap3_rom_rng_call is NULL\n");
+		return -EINVAL;
+	}
+
+	setup_timer(&idle_timer, omap3_rom_rng_idle, 0);
+	rng_clk = clk_get(&pdev->dev, "ick");
+	if (IS_ERR(rng_clk)) {
+		pr_err("unable to get RNG clock\n");
+		return PTR_ERR(rng_clk);
+	}
+
+	/* Leave the RNG in reset state. */
+	clk_prepare_enable(rng_clk);
+	omap3_rom_rng_idle(0);
+
+	return hwrng_register(&omap3_rom_rng_ops);
+}
+
+static int omap3_rom_rng_remove(struct platform_device *pdev)
+{
+	hwrng_unregister(&omap3_rom_rng_ops);
+	clk_disable_unprepare(rng_clk);
+	clk_put(rng_clk);
+	return 0;
+}
+
+static struct platform_driver omap3_rom_rng_driver = {
+	.driver = {
+		.name		= "omap3-rom-rng",
+		.owner		= THIS_MODULE,
+	},
+	.probe		= omap3_rom_rng_probe,
+	.remove		= omap3_rom_rng_remove,
+};
+
+module_platform_driver(omap3_rom_rng_driver);
+
+MODULE_ALIAS("platform:omap3-rom-rng");
+MODULE_AUTHOR("Juha Yrjola");
+MODULE_AUTHOR("Pali Rohár <[email protected]>");
+MODULE_LICENSE("GPL");