From 2bbb6983887fefc8026beab01198d30f47b7bd22 Mon Sep 17 00:00:00 2001 From: Harald Freudenberger Date: Tue, 11 Jul 2017 09:36:22 +0200 Subject: hwrng: use rng source with best quality This patch rewoks the hwrng to always use the rng source with best entropy quality. On registation and unregistration the hwrng now tries to choose the best (= highest quality value) rng source. The handling of the internal list of registered rng sources is now always sorted by quality and the top most rng chosen. Signed-off-by: Harald Freudenberger Reviewed-by: PrasannaKumar Muralidharan Signed-off-by: Herbert Xu --- drivers/char/hw_random/core.c | 25 +++++++++++++++++++------ 1 file changed, 19 insertions(+), 6 deletions(-) (limited to 'drivers/char') diff --git a/drivers/char/hw_random/core.c b/drivers/char/hw_random/core.c index 503a41dfa193..e9dda162d4d2 100644 --- a/drivers/char/hw_random/core.c +++ b/drivers/char/hw_random/core.c @@ -29,6 +29,7 @@ static struct hwrng *current_rng; static struct task_struct *hwrng_fill; +/* list of registered rngs, sorted decending by quality */ static LIST_HEAD(rng_list); /* Protects rng_list and current_rng */ static DEFINE_MUTEX(rng_mutex); @@ -417,6 +418,7 @@ int hwrng_register(struct hwrng *rng) { int err = -EINVAL; struct hwrng *old_rng, *tmp; + struct list_head *rng_list_ptr; if (!rng->name || (!rng->data_read && !rng->read)) goto out; @@ -432,14 +434,25 @@ int hwrng_register(struct hwrng *rng) init_completion(&rng->cleanup_done); complete(&rng->cleanup_done); + /* rng_list is sorted by decreasing quality */ + list_for_each(rng_list_ptr, &rng_list) { + tmp = list_entry(rng_list_ptr, struct hwrng, list); + if (tmp->quality < rng->quality) + break; + } + list_add_tail(&rng->list, rng_list_ptr); + old_rng = current_rng; err = 0; - if (!old_rng) { + if (!old_rng || (rng->quality > old_rng->quality)) { + /* + * Set new rng as current as the new rng source + * provides better entropy quality. + */ err = set_current_rng(rng); if (err) goto out_unlock; } - list_add_tail(&rng->list, &rng_list); if (old_rng && !rng->init) { /* @@ -466,12 +479,12 @@ void hwrng_unregister(struct hwrng *rng) list_del(&rng->list); if (current_rng == rng) { drop_current_rng(); + /* rng_list is sorted by quality, use the best (=first) one */ if (!list_empty(&rng_list)) { - struct hwrng *tail; - - tail = list_entry(rng_list.prev, struct hwrng, list); + struct hwrng *new_rng; - set_current_rng(tail); + new_rng = list_entry(rng_list.next, struct hwrng, list); + set_current_rng(new_rng); } } -- cgit v1.2.3 From 10a515ddb5f19a1ff0b9882c430b4427843169f3 Mon Sep 17 00:00:00 2001 From: Harald Freudenberger Date: Tue, 11 Jul 2017 09:36:23 +0200 Subject: hwrng: remember rng chosen by user When a user chooses a rng source via sysfs attribute this rng should be sticky, even when other sources with better quality to register. This patch introduces a simple way to remember the user's choice. This is reflected by a new sysfs attribute file 'rng_selected' which shows if the current rng has been chosen by userspace. The new attribute file shows '1' for user selected rng and '0' otherwise. Signed-off-by: Harald Freudenberger Reviewed-by: PrasannaKumar Muralidharan Signed-off-by: Herbert Xu --- drivers/char/hw_random/core.c | 21 +++++++++++++++++++-- 1 file changed, 19 insertions(+), 2 deletions(-) (limited to 'drivers/char') diff --git a/drivers/char/hw_random/core.c b/drivers/char/hw_random/core.c index e9dda162d4d2..9701ac7d8b47 100644 --- a/drivers/char/hw_random/core.c +++ b/drivers/char/hw_random/core.c @@ -28,6 +28,8 @@ #define RNG_MODULE_NAME "hw_random" static struct hwrng *current_rng; +/* the current rng has been explicitly chosen by user via sysfs */ +static int cur_rng_set_by_user; static struct task_struct *hwrng_fill; /* list of registered rngs, sorted decending by quality */ static LIST_HEAD(rng_list); @@ -304,6 +306,7 @@ static ssize_t hwrng_attr_current_store(struct device *dev, list_for_each_entry(rng, &rng_list, list) { if (sysfs_streq(rng->name, buf)) { err = 0; + cur_rng_set_by_user = 1; if (rng != current_rng) err = set_current_rng(rng); break; @@ -352,16 +355,27 @@ static ssize_t hwrng_attr_available_show(struct device *dev, return strlen(buf); } +static ssize_t hwrng_attr_selected_show(struct device *dev, + struct device_attribute *attr, + char *buf) +{ + return snprintf(buf, PAGE_SIZE, "%d\n", cur_rng_set_by_user); +} + static DEVICE_ATTR(rng_current, S_IRUGO | S_IWUSR, hwrng_attr_current_show, hwrng_attr_current_store); static DEVICE_ATTR(rng_available, S_IRUGO, hwrng_attr_available_show, NULL); +static DEVICE_ATTR(rng_selected, S_IRUGO, + hwrng_attr_selected_show, + NULL); static struct attribute *rng_dev_attrs[] = { &dev_attr_rng_current.attr, &dev_attr_rng_available.attr, + &dev_attr_rng_selected.attr, NULL }; @@ -444,10 +458,12 @@ int hwrng_register(struct hwrng *rng) old_rng = current_rng; err = 0; - if (!old_rng || (rng->quality > old_rng->quality)) { + if (!old_rng || + (!cur_rng_set_by_user && rng->quality > old_rng->quality)) { /* * Set new rng as current as the new rng source - * provides better entropy quality. + * provides better entropy quality and was not + * chosen by userspace. */ err = set_current_rng(rng); if (err) @@ -479,6 +495,7 @@ void hwrng_unregister(struct hwrng *rng) list_del(&rng->list); if (current_rng == rng) { drop_current_rng(); + cur_rng_set_by_user = 0; /* rng_list is sorted by quality, use the best (=first) one */ if (!list_empty(&rng_list)) { struct hwrng *new_rng; -- cgit v1.2.3 From 60f3aaee7343b15f86bcfbb02384206d8a1900cd Mon Sep 17 00:00:00 2001 From: PrasannaKumar Muralidharan Date: Fri, 21 Jul 2017 22:55:56 +0530 Subject: hwrng: Kconfig - Correct help text about feeding entropy pool Modify Kconfig help text to reflect the fact that random data from hwrng is fed into kernel random number generator's entropy pool. Signed-off-by: PrasannaKumar Muralidharan Signed-off-by: Herbert Xu --- drivers/char/hw_random/Kconfig | 6 ++---- 1 file changed, 2 insertions(+), 4 deletions(-) (limited to 'drivers/char') diff --git a/drivers/char/hw_random/Kconfig b/drivers/char/hw_random/Kconfig index 1b223c32a8ae..2f45e1532670 100644 --- a/drivers/char/hw_random/Kconfig +++ b/drivers/char/hw_random/Kconfig @@ -13,10 +13,8 @@ menuconfig HW_RANDOM that's usually called /dev/hwrng, and which exposes one of possibly several hardware random number generators. - These hardware random number generators do not feed directly - into the kernel's random number generator. That is usually - handled by the "rngd" daemon. Documentation/hw_random.txt - has more information. + These hardware random number generators do feed into the + kernel's random number generator entropy pool. If unsure, say Y. -- cgit v1.2.3 From 1d5449445bd0afbc003518543873c7198a09728b Mon Sep 17 00:00:00 2001 From: Martin Kaiser Date: Sun, 23 Jul 2017 19:49:06 +0200 Subject: hwrng: mx-rngc - add a driver for Freescale RNGC The driver is ported from Freescale's Linux git and can be found in the vendor/freescale/imx_2.6.35_maintain branch. The driver supports both RNG version C that's part of some Freescale i.MX3 SoCs and version B that is available on i.MX2x chipsets. Signed-off-by: Steffen Trumtrar Signed-off-by: Martin Kaiser Reviewed-by: PrasannaKumar Muralidharan Signed-off-by: Herbert Xu --- drivers/char/hw_random/Kconfig | 14 ++ drivers/char/hw_random/Makefile | 1 + drivers/char/hw_random/imx-rngc.c | 331 ++++++++++++++++++++++++++++++++++++++ 3 files changed, 346 insertions(+) create mode 100644 drivers/char/hw_random/imx-rngc.c (limited to 'drivers/char') diff --git a/drivers/char/hw_random/Kconfig b/drivers/char/hw_random/Kconfig index 2f45e1532670..95a031e9eced 100644 --- a/drivers/char/hw_random/Kconfig +++ b/drivers/char/hw_random/Kconfig @@ -253,6 +253,20 @@ config HW_RANDOM_MXC_RNGA If unsure, say Y. +config HW_RANDOM_IMX_RNGC + tristate "Freescale i.MX RNGC Random Number Generator" + depends on ARCH_MXC + default HW_RANDOM + ---help--- + This driver provides kernel-side support for the Random Number + Generator Version C hardware found on some Freescale i.MX + processors. Version B is also supported by this driver. + + To compile this driver as a module, choose M here: the + module will be called imx-rngc. + + If unsure, say Y. + config HW_RANDOM_NOMADIK tristate "ST-Ericsson Nomadik Random Number Generator support" depends on ARCH_NOMADIK diff --git a/drivers/char/hw_random/Makefile b/drivers/char/hw_random/Makefile index b085975ec1d2..39a67defac67 100644 --- a/drivers/char/hw_random/Makefile +++ b/drivers/char/hw_random/Makefile @@ -20,6 +20,7 @@ obj-$(CONFIG_HW_RANDOM_PASEMI) += pasemi-rng.o obj-$(CONFIG_HW_RANDOM_VIRTIO) += virtio-rng.o obj-$(CONFIG_HW_RANDOM_TX4939) += tx4939-rng.o obj-$(CONFIG_HW_RANDOM_MXC_RNGA) += mxc-rnga.o +obj-$(CONFIG_HW_RANDOM_IMX_RNGC) += imx-rngc.o obj-$(CONFIG_HW_RANDOM_OCTEON) += octeon-rng.o obj-$(CONFIG_HW_RANDOM_NOMADIK) += nomadik-rng.o obj-$(CONFIG_HW_RANDOM_PSERIES) += pseries-rng.o diff --git a/drivers/char/hw_random/imx-rngc.c b/drivers/char/hw_random/imx-rngc.c new file mode 100644 index 000000000000..88db42d30760 --- /dev/null +++ b/drivers/char/hw_random/imx-rngc.c @@ -0,0 +1,331 @@ +/* + * RNG driver for Freescale RNGC + * + * Copyright (C) 2008-2012 Freescale Semiconductor, Inc. + * Copyright (C) 2017 Martin Kaiser + * + * 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 + */ + +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include + +#define RNGC_COMMAND 0x0004 +#define RNGC_CONTROL 0x0008 +#define RNGC_STATUS 0x000C +#define RNGC_ERROR 0x0010 +#define RNGC_FIFO 0x0014 + +#define RNGC_CMD_CLR_ERR 0x00000020 +#define RNGC_CMD_CLR_INT 0x00000010 +#define RNGC_CMD_SEED 0x00000002 +#define RNGC_CMD_SELF_TEST 0x00000001 + +#define RNGC_CTRL_MASK_ERROR 0x00000040 +#define RNGC_CTRL_MASK_DONE 0x00000020 + +#define RNGC_STATUS_ERROR 0x00010000 +#define RNGC_STATUS_FIFO_LEVEL_MASK 0x00000f00 +#define RNGC_STATUS_FIFO_LEVEL_SHIFT 8 +#define RNGC_STATUS_SEED_DONE 0x00000020 +#define RNGC_STATUS_ST_DONE 0x00000010 + +#define RNGC_ERROR_STATUS_STAT_ERR 0x00000008 + +#define RNGC_TIMEOUT 3000 /* 3 sec */ + + +static bool self_test = true; +module_param(self_test, bool, 0); + +struct imx_rngc { + struct device *dev; + struct clk *clk; + void __iomem *base; + struct hwrng rng; + struct completion rng_op_done; + /* + * err_reg is written only by the irq handler and read only + * when interrupts are masked, we need no spinlock + */ + u32 err_reg; +}; + + +static inline void imx_rngc_irq_mask_clear(struct imx_rngc *rngc) +{ + u32 ctrl, cmd; + + /* mask interrupts */ + ctrl = readl(rngc->base + RNGC_CONTROL); + ctrl |= RNGC_CTRL_MASK_DONE | RNGC_CTRL_MASK_ERROR; + writel(ctrl, rngc->base + RNGC_CONTROL); + + /* + * CLR_INT clears the interrupt only if there's no error + * CLR_ERR clear the interrupt and the error register if there + * is an error + */ + cmd = readl(rngc->base + RNGC_COMMAND); + cmd |= RNGC_CMD_CLR_INT | RNGC_CMD_CLR_ERR; + writel(cmd, rngc->base + RNGC_COMMAND); +} + +static inline void imx_rngc_irq_unmask(struct imx_rngc *rngc) +{ + u32 ctrl; + + ctrl = readl(rngc->base + RNGC_CONTROL); + ctrl &= ~(RNGC_CTRL_MASK_DONE | RNGC_CTRL_MASK_ERROR); + writel(ctrl, rngc->base + RNGC_CONTROL); +} + +static int imx_rngc_self_test(struct imx_rngc *rngc) +{ + u32 cmd; + int ret; + + imx_rngc_irq_unmask(rngc); + + /* run self test */ + cmd = readl(rngc->base + RNGC_COMMAND); + writel(cmd | RNGC_CMD_SELF_TEST, rngc->base + RNGC_COMMAND); + + ret = wait_for_completion_timeout(&rngc->rng_op_done, RNGC_TIMEOUT); + if (!ret) { + imx_rngc_irq_mask_clear(rngc); + return -ETIMEDOUT; + } + + if (rngc->err_reg != 0) + return -EIO; + + return 0; +} + +static int imx_rngc_read(struct hwrng *rng, void *data, size_t max, bool wait) +{ + struct imx_rngc *rngc = container_of(rng, struct imx_rngc, rng); + unsigned int status; + unsigned int level; + int retval = 0; + + while (max >= sizeof(u32)) { + status = readl(rngc->base + RNGC_STATUS); + + /* is there some error while reading this random number? */ + if (status & RNGC_STATUS_ERROR) + break; + + /* how many random numbers are in FIFO? [0-16] */ + level = (status & RNGC_STATUS_FIFO_LEVEL_MASK) >> + RNGC_STATUS_FIFO_LEVEL_SHIFT; + + if (level) { + /* retrieve a random number from FIFO */ + *(u32 *)data = readl(rngc->base + RNGC_FIFO); + + retval += sizeof(u32); + data += sizeof(u32); + max -= sizeof(u32); + } + } + + return retval ? retval : -EIO; +} + +static irqreturn_t imx_rngc_irq(int irq, void *priv) +{ + struct imx_rngc *rngc = (struct imx_rngc *)priv; + u32 status; + + /* + * clearing the interrupt will also clear the error register + * read error and status before clearing + */ + status = readl(rngc->base + RNGC_STATUS); + rngc->err_reg = readl(rngc->base + RNGC_ERROR); + + imx_rngc_irq_mask_clear(rngc); + + if (status & (RNGC_STATUS_SEED_DONE | RNGC_STATUS_ST_DONE)) + complete(&rngc->rng_op_done); + + return IRQ_HANDLED; +} + +static int imx_rngc_init(struct hwrng *rng) +{ + struct imx_rngc *rngc = container_of(rng, struct imx_rngc, rng); + u32 cmd; + int ret; + + /* clear error */ + cmd = readl(rngc->base + RNGC_COMMAND); + writel(cmd | RNGC_CMD_CLR_ERR, rngc->base + RNGC_COMMAND); + + /* create seed, repeat while there is some statistical error */ + do { + imx_rngc_irq_unmask(rngc); + + /* seed creation */ + cmd = readl(rngc->base + RNGC_COMMAND); + writel(cmd | RNGC_CMD_SEED, rngc->base + RNGC_COMMAND); + + ret = wait_for_completion_timeout(&rngc->rng_op_done, + RNGC_TIMEOUT); + + if (!ret) { + imx_rngc_irq_mask_clear(rngc); + return -ETIMEDOUT; + } + + } while (rngc->err_reg == RNGC_ERROR_STATUS_STAT_ERR); + + return rngc->err_reg ? -EIO : 0; +} + +static int imx_rngc_probe(struct platform_device *pdev) +{ + struct imx_rngc *rngc; + struct resource *res; + int ret; + int irq; + + rngc = devm_kzalloc(&pdev->dev, sizeof(*rngc), GFP_KERNEL); + if (!rngc) + return -ENOMEM; + + res = platform_get_resource(pdev, IORESOURCE_MEM, 0); + rngc->base = devm_ioremap_resource(&pdev->dev, res); + if (IS_ERR(rngc->base)) + return PTR_ERR(rngc->base); + + rngc->clk = devm_clk_get(&pdev->dev, NULL); + if (IS_ERR(rngc->clk)) { + dev_err(&pdev->dev, "Can not get rng_clk\n"); + return PTR_ERR(rngc->clk); + } + + irq = platform_get_irq(pdev, 0); + if (irq <= 0) { + dev_err(&pdev->dev, "Couldn't get irq %d\n", irq); + return irq; + } + + ret = clk_prepare_enable(rngc->clk); + if (ret) + return ret; + + ret = devm_request_irq(&pdev->dev, + irq, imx_rngc_irq, 0, pdev->name, (void *)rngc); + if (ret) { + dev_err(rngc->dev, "Can't get interrupt working.\n"); + goto err; + } + + init_completion(&rngc->rng_op_done); + + rngc->rng.name = pdev->name; + rngc->rng.init = imx_rngc_init; + rngc->rng.read = imx_rngc_read; + + rngc->dev = &pdev->dev; + platform_set_drvdata(pdev, rngc); + + imx_rngc_irq_mask_clear(rngc); + + if (self_test) { + ret = imx_rngc_self_test(rngc); + if (ret) { + dev_err(rngc->dev, "FSL RNGC self test failed.\n"); + goto err; + } + } + + ret = hwrng_register(&rngc->rng); + if (ret) { + dev_err(&pdev->dev, "FSL RNGC registering failed (%d)\n", ret); + goto err; + } + + dev_info(&pdev->dev, "Freescale RNGC registered.\n"); + return 0; + +err: + clk_disable_unprepare(rngc->clk); + + return ret; +} + +static int __exit imx_rngc_remove(struct platform_device *pdev) +{ + struct imx_rngc *rngc = platform_get_drvdata(pdev); + + hwrng_unregister(&rngc->rng); + + clk_disable_unprepare(rngc->clk); + + return 0; +} + +#ifdef CONFIG_PM +static int imx_rngc_suspend(struct device *dev) +{ + struct imx_rngc *rngc = dev_get_drvdata(dev); + + clk_disable_unprepare(rngc->clk); + + return 0; +} + +static int imx_rngc_resume(struct device *dev) +{ + struct imx_rngc *rngc = dev_get_drvdata(dev); + + clk_prepare_enable(rngc->clk); + + return 0; +} + +static const struct dev_pm_ops imx_rngc_pm_ops = { + .suspend = imx_rngc_suspend, + .resume = imx_rngc_resume, +}; +#endif + +static const struct of_device_id imx_rngc_dt_ids[] = { + { .compatible = "fsl,imx25-rngb", .data = NULL, }, + { /* sentinel */ } +}; +MODULE_DEVICE_TABLE(of, imx_rngc_dt_ids); + +static struct platform_driver imx_rngc_driver = { + .driver = { + .name = "imx_rngc", +#ifdef CONFIG_PM + .pm = &imx_rngc_pm_ops, +#endif + .of_match_table = imx_rngc_dt_ids, + }, + .remove = __exit_p(imx_rngc_remove), +}; + +module_platform_driver_probe(imx_rngc_driver, imx_rngc_probe); + +MODULE_AUTHOR("Freescale Semiconductor, Inc."); +MODULE_DESCRIPTION("H/W RNGC driver for i.MX"); +MODULE_LICENSE("GPL"); -- cgit v1.2.3