From: Kieran Bingham Subject: Re: [PATCH 4/6] hwrng: st: Add support for ST's HW Random Number Generator Date: Sat, 12 Sep 2015 23:58:55 +0100 Message-ID: References: <1442002110-28733-1-git-send-email-lee.jones@linaro.org> <1442002110-28733-5-git-send-email-lee.jones@linaro.org> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Cc: linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, kernel@stlinux.com, mpm@selenic.com, herbert@gondor.apana.org.au, linux-crypto@vger.kernel.org, devicetree@vger.kernel.org, Pankaj Dev To: Lee Jones Return-path: Received: from mail-la0-f49.google.com ([209.85.215.49]:33695 "EHLO mail-la0-f49.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753915AbbILW65 (ORCPT ); Sat, 12 Sep 2015 18:58:57 -0400 In-Reply-To: <1442002110-28733-5-git-send-email-lee.jones@linaro.org> Sender: linux-crypto-owner@vger.kernel.org List-ID: Hi Lee, On 11 September 2015 at 21:08, Lee Jones wrote: > Signed-off-by: Pankaj Dev > Signed-off-by: Lee Jones > --- > drivers/char/hw_random/Kconfig | 10 +++ > drivers/char/hw_random/Makefile | 1 + > drivers/char/hw_random/st-rng.c | 142 ++++++++++++++++++++++++++++++++++++++++ > 3 files changed, 153 insertions(+) > create mode 100644 drivers/char/hw_random/st-rng.c > > diff --git a/drivers/char/hw_random/Kconfig b/drivers/char/hw_random/Kconfig > index f48cf11..bb6cb77 100644 > --- a/drivers/char/hw_random/Kconfig > +++ b/drivers/char/hw_random/Kconfig > @@ -346,6 +346,16 @@ config HW_RANDOM_MSM > > If unsure, say Y. > > +config HW_RANDOM_ST > + tristate "ST Microelectronics HW Random Number Generator support" > + depends on HW_RANDOM && ARCH_STI > + ---help--- > + This driver provides kernel-side support for the Random Number > + Generator hardware found on STi series of SoCs. > + > + To compile this driver as a module, choose M here: the > + module will be called st-rng. > + > config HW_RANDOM_XGENE > tristate "APM X-Gene True Random Number Generator (TRNG) support" > depends on HW_RANDOM && ARCH_XGENE > diff --git a/drivers/char/hw_random/Makefile b/drivers/char/hw_random/Makefile > index 055bb01..8bcfb45 100644 > --- a/drivers/char/hw_random/Makefile > +++ b/drivers/char/hw_random/Makefile > @@ -30,4 +30,5 @@ obj-$(CONFIG_HW_RANDOM_TPM) += tpm-rng.o > obj-$(CONFIG_HW_RANDOM_BCM2835) += bcm2835-rng.o > obj-$(CONFIG_HW_RANDOM_IPROC_RNG200) += iproc-rng200.o > obj-$(CONFIG_HW_RANDOM_MSM) += msm-rng.o > +obj-$(CONFIG_HW_RANDOM_ST) += st-rng.o > obj-$(CONFIG_HW_RANDOM_XGENE) += xgene-rng.o > diff --git a/drivers/char/hw_random/st-rng.c b/drivers/char/hw_random/st-rng.c > new file mode 100644 > index 0000000..717a831 > --- /dev/null > +++ b/drivers/char/hw_random/st-rng.c > @@ -0,0 +1,142 @@ > +/* > + * ST Random Number Generator Driver ST's Platforms > + * > + * Author: Pankaj Dev: > + * Lee Jones > + * > + * Copyright (C) 2015 STMicroelectronics (R&D) Limited > + * > + * This program is free software; you can redistribute it and/or modify > + * it under the terms of the GNU General Public License version 2 as > + * published by the Free Software Foundation. > + */ > + > +#include > +#include > +#include > +#include > +#include > +#include > +#include > +#include > + > +/* Registers */ > +#define ST_RNG_STATUS_REG 0x20 > +#define ST_RNG_DATA_REG 0x24 > + > +/* Registers fields */ > +#define ST_RNG_STATUS_BAD_SEQUENCE BIT(0) > +#define ST_RNG_STATUS_BAD_ALTERNANCE BIT(1) > +#define ST_RNG_STATUS_FIFO_FULL BIT(5) > + > +#define ST_RNG_FIFO_SIZE 8 > +#define ST_RNG_SAMPLE_SIZE 2 /* 2 Byte (16bit) samples */ > + > +/* Samples are available every 0.667us, which we round to 1us */ > +#define ST_RNG_FILL_FIFO_TIMEOUT (1 * (ST_RNG_FIFO_SIZE / ST_RNG_SAMPLE_SIZE)) > + > +struct st_rng_data { > + void __iomem *base; > + struct clk *clk; > + struct hwrng ops; > +}; > + > +static int st_rng_read(struct hwrng *rng, void *data, size_t max, bool wait) > +{ > + struct st_rng_data *ddata = (struct st_rng_data *)rng->priv; > + u32 status; > + int i; > + > + if (max < sizeof(u16)) > + return -EINVAL; > + > + /* Wait until FIFO is full - max 4uS*/ > + for (i = 0; i < ST_RNG_FILL_FIFO_TIMEOUT; i++) { > + status = readl_relaxed(ddata->base + ST_RNG_STATUS_REG); > + if (status & ST_RNG_STATUS_FIFO_FULL) > + break; > + udelay(1); > + } > + > + if (i == ST_RNG_FILL_FIFO_TIMEOUT) > + return 0; > + > + for (i = 0; i < ST_RNG_FIFO_SIZE && i < max; i += 2) > + *(u16 *)(data + i) = > + readl_relaxed(ddata->base + ST_RNG_DATA_REG); Will this code always be called with max % 2 == 0? ... I.e. will st_rng_read(rng, data[5], 5, waitflg) overflow an array? > + > + return i - 2; /* No of bytes read */ Really? Doesn't this return 0 on st_rng_read(rng, data[2], 2, waitflg); > +} > + > +static int st_rng_probe(struct platform_device *pdev) > +{ > + struct st_rng_data *ddata; > + struct resource *res; > + struct clk *clk; > + void __iomem *base; > + int ret; > + > + ddata = devm_kzalloc(&pdev->dev, sizeof(*ddata), GFP_KERNEL); > + if (!ddata) > + return -ENOMEM; > + > + res = platform_get_resource(pdev, IORESOURCE_MEM, 0); > + base = devm_ioremap_resource(&pdev->dev, res); > + if (IS_ERR(base)) Are we leaking ddata here ? I.e. before its attached with set_drvdata? > + return PTR_ERR(base); > + > + clk = devm_clk_get(&pdev->dev, NULL); > + if (!clk) And here ... > + return -EINVAL; > + > + clk_prepare_enable(clk); > + > + ddata->ops.priv = (unsigned long)ddata; > + ddata->ops.read = st_rng_read; > + ddata->ops.name = pdev->name; > + ddata->base = base; > + ddata->clk = clk; > + > + dev_set_drvdata(&pdev->dev, ddata); > + > + ret = hwrng_register(&ddata->ops); > + if (ret) { > + dev_err(&pdev->dev, "Failed to register HW RNG\n"); > + return ret; > + } > + > + dev_info(&pdev->dev, "Successfully registered HW RNG\n"); > + > + return 0; > +} > + > +static int st_rng_remove(struct platform_device *pdev) > +{ > + struct st_rng_data *ddata = dev_get_drvdata(&pdev->dev); > + > + hwrng_unregister(&ddata->ops); > + > + clk_disable_unprepare(ddata->clk); > + > + return 0; > +} > + > +static const struct of_device_id st_rng_match[] = { > + { .compatible = "st,rng" }, > + {}, > +}; > +MODULE_DEVICE_TABLE(of, st_rng_match); > + > +static struct platform_driver st_rng_driver = { > + .driver = { > + .name = "st-hwrandom", > + .of_match_table = of_match_ptr(st_rng_match), > + }, > + .probe = st_rng_probe, > + .remove = st_rng_remove > +}; > + > +module_platform_driver(st_rng_driver); > + > +MODULE_AUTHOR("Pankaj Dev "); > +MODULE_LICENSE("GPL v2"); > -- > 1.9.1 > > -- > To unsubscribe from this list: send the line "unsubscribe devicetree" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html -- Regards Kieran Now available for: $GREATCOMPANY add -A linuxdevs/kieranbingham/ && \ $GREATCOMPANY commit -m "HR: Add fantastic new employee"