From: Joshua Henderson Subject: [PATCH v2 2/2] rng: pic32-rng: Add PIC32 RNG hardware driver Date: Mon, 8 Feb 2016 14:17:53 -0700 Message-ID: <1454966283-14965-2-git-send-email-joshua.henderson@microchip.com> References: <1454966283-14965-1-git-send-email-joshua.henderson@microchip.com> Mime-Version: 1.0 Content-Type: text/plain Cc: Joshua Henderson , Purna Chandra Mandal , Rob Herring , Pawel Moll , Mark Rutland , Ian Campbell , Kumar Gala , Matt Mackall , Herbert Xu , Kieran Bingham , Lee Jones , Pankaj Dev , Scott Branden , Daniel Thompson , Ray Jui , To: , Return-path: In-Reply-To: <1454966283-14965-1-git-send-email-joshua.henderson@microchip.com> Sender: linux-kernel-owner@vger.kernel.org List-Id: linux-crypto.vger.kernel.org Add support for the hardware true random number generator peripheral found on PIC32. Signed-off-by: Joshua Henderson Signed-off-by: Purna Chandra Mandal --- Changes since v1: - Reorder includes to be alphabetic. - Drop use of PRNG and only use TRNG. - Fix dangling clock ref in error condition. - Remove unecessary error handling and fix other cases. --- drivers/char/hw_random/Kconfig | 13 +++ drivers/char/hw_random/Makefile | 1 + drivers/char/hw_random/pic32-rng.c | 155 ++++++++++++++++++++++++++++++++++++ 3 files changed, 169 insertions(+) create mode 100644 drivers/char/hw_random/pic32-rng.c diff --git a/drivers/char/hw_random/Kconfig b/drivers/char/hw_random/Kconfig index dbf2271..3ab0c46 100644 --- a/drivers/char/hw_random/Kconfig +++ b/drivers/char/hw_random/Kconfig @@ -381,6 +381,19 @@ config HW_RANDOM_STM32 If unsure, say N. +config HW_RANDOM_PIC32 + tristate "Microchip PIC32 Random Number Generator support" + depends on HW_RANDOM && MACH_PIC32 + default y + ---help--- + This driver provides kernel-side support for the Random Number + Generator hardware found on a PIC32. + + To compile this driver as a module, choose M here. the + module will be called pic32-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 5ad3976..f5a6fa7 100644 --- a/drivers/char/hw_random/Makefile +++ b/drivers/char/hw_random/Makefile @@ -33,3 +33,4 @@ obj-$(CONFIG_HW_RANDOM_MSM) += msm-rng.o obj-$(CONFIG_HW_RANDOM_ST) += st-rng.o obj-$(CONFIG_HW_RANDOM_XGENE) += xgene-rng.o obj-$(CONFIG_HW_RANDOM_STM32) += stm32-rng.o +obj-$(CONFIG_HW_RANDOM_PIC32) += pic32-rng.o diff --git a/drivers/char/hw_random/pic32-rng.c b/drivers/char/hw_random/pic32-rng.c new file mode 100644 index 0000000..108897b --- /dev/null +++ b/drivers/char/hw_random/pic32-rng.c @@ -0,0 +1,155 @@ +/* + * PIC32 RNG driver + * + * Joshua Henderson + * Copyright (C) 2016 Microchip Technology Inc. All rights reserved. + * + * This program is free software; you can distribute it and/or modify it + * under the terms of the GNU General Public License (Version 2) as + * published by the Free Software Foundation. + * + * This program is distributed in the hope it will be useful, but WITHOUT + * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or + * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License + * for more details. + */ + +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include + +#define RNGCON 0x04 +#define TRNGEN BIT(8) +#define PRNGEN BIT(9) +#define PRNGCONT BIT(10) +#define TRNGMOD BIT(11) +#define SEEDLOAD BIT(12) +#define RNGPOLY1 0x08 +#define RNGPOLY2 0x0C +#define RNGNUMGEN1 0x10 +#define RNGNUMGEN2 0x14 +#define RNGSEED1 0x18 +#define RNGSEED2 0x1C +#define RNGRCNT 0x20 +#define RCNT_MASK 0x7F + +struct pic32_rng { + void __iomem *base; + struct hwrng rng; + struct clk *clk; +}; + +/* + * The TRNG can generate up to 24Mbps. This is a timeout that should be safe + * enough given the instructions in the loop and that the TRNG may not always + * be at maximum rate. + */ +#define RNG_TIMEOUT 500 + +static int pic32_rng_read(struct hwrng *rng, void *buf, size_t max, + bool wait) +{ + struct pic32_rng *priv = container_of(rng, struct pic32_rng, rng); + u64 *data = buf; + u32 t; + unsigned int timeout = RNG_TIMEOUT; + + if (max < 8) + return 0; + + do { + t = readl(priv->base + RNGRCNT) & RCNT_MASK; + if (t == 64) { + /* TRNG value comes through the seed registers */ + *data = ((u64)readl(priv->base + RNGSEED2) << 32) + + readl(priv->base + RNGSEED1); + return 8; + } + } while (wait && --timeout); + + return -EIO; +} + +static int pic32_rng_probe(struct platform_device *pdev) +{ + struct pic32_rng *priv; + struct resource *res; + u32 v; + int ret; + + priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL); + if (!priv) + return -ENOMEM; + + res = platform_get_resource(pdev, IORESOURCE_MEM, 0); + priv->base = devm_ioremap_resource(&pdev->dev, res); + if (IS_ERR(priv->base)) + return PTR_ERR(priv->base); + + priv->clk = devm_clk_get(&pdev->dev, NULL); + if (IS_ERR(priv->clk)) + return PTR_ERR(priv->clk); + + ret = clk_prepare_enable(priv->clk); + if (ret) + return ret; + + /* enable TRNG in enhanced mode */ + v = TRNGEN | TRNGMOD; + writel(v, priv->base + RNGCON); + + priv->rng.name = pdev->name; + priv->rng.read = pic32_rng_read; + + ret = hwrng_register(&priv->rng); + if (ret) + goto err_register; + + platform_set_drvdata(pdev, priv); + + return 0; + +err_register: + clk_disable_unprepare(priv->clk); + return ret; +} + +static int pic32_rng_remove(struct platform_device *pdev) +{ + struct pic32_rng *rng = platform_get_drvdata(pdev); + + hwrng_unregister(&rng->rng); + writel(0, rng->base + RNGCON); + clk_disable_unprepare(rng->clk); + return 0; +} + +static const struct of_device_id pic32_rng_of_match[] = { + { .compatible = "microchip,pic32mzda-rng", }, + { /* sentinel */ } +}; +MODULE_DEVICE_TABLE(of, pic32_rng_of_match); + +static struct platform_driver pic32_rng_driver = { + .probe = pic32_rng_probe, + .remove = pic32_rng_remove, + .driver = { + .name = "pic32-rng", + .owner = THIS_MODULE, + .of_match_table = of_match_ptr(pic32_rng_of_match), + }, +}; + +module_platform_driver(pic32_rng_driver); + +MODULE_LICENSE("GPL"); +MODULE_AUTHOR("Joshua Henderson "); +MODULE_DESCRIPTION("Microchip PIC32 RNG Driver"); -- 1.7.9.5