From: PrasannaKumar Muralidharan Subject: [PATCH v2 2/4] hw_random: jz4780-rng: Add Ingenic JZ4780 hardware RNG driver Date: Sat, 27 Aug 2016 23:44:55 +0530 Message-ID: <1472321697-3094-3-git-send-email-prasannatsmkumar@gmail.com> References: <1472321697-3094-1-git-send-email-prasannatsmkumar@gmail.com> Cc: PrasannaKumar Muralidharan To: mpm@selenic.com, herbert@gondor.apana.org.au, robh+dt@kernel.org, mark.rutland@arm.com, ralf@linux-mips.org, gregkh@linuxfoundation.org, boris.brezillon@free-electrons.com, harvey.hunt@imgtec.com, prarit@redhat.com, f.fainelli@gmail.com, joshua.henderson@microchip.com, narmstrong@baylibre.com, linus.walleij@linaro.org, linux-crypto@vger.kernel.org, devicetree@vger.kernel.org, linux-mips@linux-mips.org Return-path: Received: from mail-pf0-f196.google.com ([209.85.192.196]:33968 "EHLO mail-pf0-f196.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754628AbcH0SP6 (ORCPT ); Sat, 27 Aug 2016 14:15:58 -0400 In-Reply-To: <1472321697-3094-1-git-send-email-prasannatsmkumar@gmail.com> Sender: linux-crypto-owner@vger.kernel.org List-ID: JZ4780 SoC random number generator driver. Changes since v1: * Use devm_ioremap_resource and devm_hwrng_register * Add delay after enabling RNG, before reading data * Disable RNG after reading data as per Ingenic JZ4780 PM * Move Makefile and Kconfig entries to the bottom * Arrange includes in alphabetical order Adding a delay before reading RNG data and disabling RNG after reading data was suggested by Jeffery Walton. Suggested-by: Jeffrey Walton Signed-off-by: PrasannaKumar Muralidharan --- MAINTAINERS | 5 ++ drivers/char/hw_random/Kconfig | 14 +++++ drivers/char/hw_random/Makefile | 1 + drivers/char/hw_random/jz4780-rng.c | 101 ++++++++++++++++++++++++++++++++++++ 4 files changed, 121 insertions(+) create mode 100644 drivers/char/hw_random/jz4780-rng.c diff --git a/MAINTAINERS b/MAINTAINERS index 320cce8..87a7505 100644 --- a/MAINTAINERS +++ b/MAINTAINERS @@ -6008,6 +6008,11 @@ M: Zubair Lutfullah Kakakhel S: Maintained F: drivers/dma/dma-jz4780.c +INGENIC JZ4780 HW RNG Driver +M: PrasannaKumar Muralidharan +S: Maintained +F: drivers/char/hw_random/jz4780-rng.c + INTEGRITY MEASUREMENT ARCHITECTURE (IMA) M: Mimi Zohar M: Dmitry Kasatkin diff --git a/drivers/char/hw_random/Kconfig b/drivers/char/hw_random/Kconfig index 56ad5a59..662e415 100644 --- a/drivers/char/hw_random/Kconfig +++ b/drivers/char/hw_random/Kconfig @@ -410,6 +410,20 @@ config HW_RANDOM_MESON If unsure, say Y. +config HW_RANDOM_JZ4780 + tristate "JZ4780 HW random number generator support" + depends on MACH_INGENIC + depends on HAS_IOMEM + default HW_RANDOM + ---help--- + This driver provides kernel-side support for the Random Number + Generator hardware found on JZ4780 SOCs. + + To compile this driver as a module, choose M here: the + module will be called jz4780-rng. + + If unsure, say Y. + endif # HW_RANDOM config UML_RANDOM diff --git a/drivers/char/hw_random/Makefile b/drivers/char/hw_random/Makefile index 04bb0b0..df1dbf6 100644 --- a/drivers/char/hw_random/Makefile +++ b/drivers/char/hw_random/Makefile @@ -35,3 +35,4 @@ obj-$(CONFIG_HW_RANDOM_XGENE) += xgene-rng.o obj-$(CONFIG_HW_RANDOM_STM32) += stm32-rng.o obj-$(CONFIG_HW_RANDOM_PIC32) += pic32-rng.o obj-$(CONFIG_HW_RANDOM_MESON) += meson-rng.o +obj-$(CONFIG_HW_RANDOM_JZ4780) += jz4780-rng.o diff --git a/drivers/char/hw_random/jz4780-rng.c b/drivers/char/hw_random/jz4780-rng.c new file mode 100644 index 0000000..1c85ed0 --- /dev/null +++ b/drivers/char/hw_random/jz4780-rng.c @@ -0,0 +1,101 @@ +/* + * jz4780-rng.c - Random Number Generator driver for J4780 + * + * Copyright 2016 (C) PrasannaKumar Muralidharan + * + * 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 +#include +#include +#include +#include +#include +#include +#include + +#define REG_RNG_CTRL 0x0 +#define REG_RNG_DATA 0x4 + +struct jz4780_rng { + struct device *dev; + struct hwrng rng; + void __iomem *mem; +}; + +static u32 jz4780_rng_readl(struct jz4780_rng *rng, u32 offset) +{ + return readl(rng->mem + offset); +} + +static void jz4780_rng_writel(struct jz4780_rng *rng, u32 val, u32 offset) +{ + writel(val, rng->mem + offset); +} + +static int jz4780_rng_read(struct hwrng *rng, void *buf, size_t max, bool wait) +{ + struct jz4780_rng *jz4780_rng = container_of(rng, struct jz4780_rng, + rng); + u32 *data = buf; + /* + * JZ4780 Programmers manual says the RNG should not run continuously + * for more than 1s. So enable RNG, read data and disable it. + * NOTE: No issue was observed with MIPS creator CI20 board even when + * RNG ran continuously for longer periods. This is just a precaution. + * + * A delay is required so that the current RNG data is not bit shifted + * version of previous RNG data which could happen if random data is + * read continuously from this device. + */ + jz4780_rng_writel(jz4780_rng, 1, REG_RNG_CTRL); + /* As the delay is small add it even if wait is false */ + udelay(20); + *data = jz4780_rng_readl(jz4780_rng, REG_RNG_DATA); + jz4780_rng_writel(jz4780_rng, 0, REG_RNG_CTRL); + + return 4; +} + +static int jz4780_rng_probe(struct platform_device *pdev) +{ + struct jz4780_rng *jz4780_rng; + struct resource *res; + + jz4780_rng = devm_kzalloc(&pdev->dev, sizeof(*jz4780_rng), GFP_KERNEL); + if (!jz4780_rng) + return -ENOMEM; + + jz4780_rng->dev = &pdev->dev; + jz4780_rng->rng.name = "jz4780"; + jz4780_rng->rng.read = jz4780_rng_read; + + res = platform_get_resource(pdev, IORESOURCE_MEM, 0); + jz4780_rng->mem = devm_ioremap_resource(&pdev->dev, res); + if (IS_ERR(jz4780_rng->mem)) + return PTR_ERR(jz4780_rng->mem); + + return devm_hwrng_register(&pdev->dev, &jz4780_rng->rng); +} + +static const struct of_device_id jz4780_rng_dt_match[] = { + { .compatible = "ingenic,jz4780-rng", }, + { }, +}; +MODULE_DEVICE_TABLE(of, jz4780_rng_dt_match); + +static struct platform_driver jz4780_rng_driver = { + .driver = { + .name = "jz4780-rng", + .of_match_table = jz4780_rng_dt_match, + }, + .probe = jz4780_rng_probe, +}; +module_platform_driver(jz4780_rng_driver); + +MODULE_DESCRIPTION("Ingenic JZ4780 H/W Random Number Generator driver"); +MODULE_AUTHOR("PrasannaKumar Muralidharan "); +MODULE_LICENSE("GPL"); -- 2.5.0