diff options
Diffstat (limited to 'drivers/hw_random/bcm2835-rng.c')
| -rw-r--r-- | drivers/hw_random/bcm2835-rng.c | 199 |
1 files changed, 199 insertions, 0 deletions
diff --git a/drivers/hw_random/bcm2835-rng.c b/drivers/hw_random/bcm2835-rng.c new file mode 100644 index 0000000000..d82331c950 --- /dev/null +++ b/drivers/hw_random/bcm2835-rng.c @@ -0,0 +1,199 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Copyright (c) 2010-2012 Broadcom. All rights reserved. + * Copyright (c) 2013 Lubomir Rintel + */ + +#include <linux/hw_random.h> +#include <linux/io.h> +#include <linux/kernel.h> +#include <linux/reset.h> +#include <of.h> +#include <linux/device.h> +#include <linux/printk.h> +#include <linux/clk.h> +#include <linux/reset.h> + +#define RNG_CTRL 0x0 +#define RNG_STATUS 0x4 +#define RNG_DATA 0x8 +#define RNG_INT_MASK 0x10 + +/* enable rng */ +#define RNG_RBGEN 0x1 + +/* the initial numbers generated are "less random" so will be discarded */ +#define RNG_WARMUP_COUNT 0x40000 + +#define RNG_INT_OFF 0x1 + +struct bcm2835_rng_priv { + struct hwrng rng; + void __iomem *base; + bool mask_interrupts; + struct clk *clk; + struct reset_control *reset; +}; + +static inline struct bcm2835_rng_priv *to_rng_priv(struct hwrng *rng) +{ + return container_of(rng, struct bcm2835_rng_priv, rng); +} + +static inline u32 rng_readl(struct bcm2835_rng_priv *priv, u32 offset) +{ + /* MIPS chips strapped for BE will automagically configure the + * peripheral registers for CPU-native byte order. + */ + if (IS_ENABLED(CONFIG_MIPS) && IS_ENABLED(CONFIG_CPU_BIG_ENDIAN)) + return __raw_readl(priv->base + offset); + else + return readl(priv->base + offset); +} + +static inline void rng_writel(struct bcm2835_rng_priv *priv, u32 val, + u32 offset) +{ + if (IS_ENABLED(CONFIG_MIPS) && IS_ENABLED(CONFIG_CPU_BIG_ENDIAN)) + __raw_writel(val, priv->base + offset); + else + writel(val, priv->base + offset); +} + +static int bcm2835_rng_read(struct hwrng *rng, void *buf, size_t max, + bool wait) +{ + struct bcm2835_rng_priv *priv = to_rng_priv(rng); + u32 max_words = max / sizeof(u32); + u32 num_words, count; + + while ((rng_readl(priv, RNG_STATUS) >> 24) == 0) { + if (!wait) + return 0; + hwrng_yield(rng); + } + + num_words = rng_readl(priv, RNG_STATUS) >> 24; + if (num_words > max_words) + num_words = max_words; + + for (count = 0; count < num_words; count++) + ((u32 *)buf)[count] = rng_readl(priv, RNG_DATA); + + return num_words * sizeof(u32); +} + +static int bcm2835_rng_init(struct hwrng *rng) +{ + struct bcm2835_rng_priv *priv = to_rng_priv(rng); + int ret = 0; + u32 val; + + ret = clk_prepare_enable(priv->clk); + if (ret) + return ret; + + ret = reset_control_reset(priv->reset); + if (ret) + return ret; + + if (priv->mask_interrupts) { + /* mask the interrupt */ + val = rng_readl(priv, RNG_INT_MASK); + val |= RNG_INT_OFF; + rng_writel(priv, val, RNG_INT_MASK); + } + + /* set warm-up count & enable */ + rng_writel(priv, RNG_WARMUP_COUNT, RNG_STATUS); + rng_writel(priv, RNG_RBGEN, RNG_CTRL); + + return ret; +} + +static void bcm2835_rng_cleanup(struct bcm2835_rng_priv *priv) +{ + /* disable rng hardware */ + rng_writel(priv, 0, RNG_CTRL); + + clk_disable_unprepare(priv->clk); +} + +struct bcm2835_rng_of_data { + bool mask_interrupts; +}; + +static const struct bcm2835_rng_of_data nsp_rng_of_data = { + .mask_interrupts = true, +}; + +static const struct of_device_id bcm2835_rng_of_match[] = { + { .compatible = "brcm,bcm2835-rng"}, + { .compatible = "brcm,bcm-nsp-rng", .data = &nsp_rng_of_data }, + { .compatible = "brcm,bcm5301x-rng", .data = &nsp_rng_of_data }, + { .compatible = "brcm,bcm6368-rng"}, + {}, +}; + +static int bcm2835_rng_probe(struct device *dev) +{ + const struct bcm2835_rng_of_data *of_data; + struct bcm2835_rng_priv *priv; + int err; + + priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL); + if (!priv) + return -ENOMEM; + + /* map peripheral */ + priv->base = dev_platform_ioremap_resource(dev, 0); + if (IS_ERR(priv->base)) + return PTR_ERR(priv->base); + + /* Clock is optional on most platforms */ + priv->clk = clk_get_optional(dev, NULL); + if (IS_ERR(priv->clk)) + return PTR_ERR(priv->clk); + + priv->reset = reset_control_get_optional(dev, NULL); + if (IS_ERR(priv->reset)) + return PTR_ERR(priv->reset); + + priv->rng.name = dev_name(dev); + priv->rng.init = bcm2835_rng_init; + priv->rng.read = bcm2835_rng_read; + + of_data = device_get_match_data(dev); + if (of_data) + priv->mask_interrupts = of_data->mask_interrupts; + + /* register driver */ + err = hwrng_register(dev, &priv->rng); + if (err) + dev_err(dev, "hwrng registration failed\n"); + else + dev_info(dev, "hwrng registered\n"); + + dev->priv = priv; + + return err; +} + +static void bcm2835_rng_remove(struct device *dev) +{ + bcm2835_rng_cleanup(dev->priv); +} + +MODULE_DEVICE_TABLE(of, bcm2835_rng_of_match); + +static struct driver bcm2835_rng_driver = { + .name = "bcm2835-rng", + .of_match_table = bcm2835_rng_of_match, + .probe = bcm2835_rng_probe, + .remove = bcm2835_rng_remove, +}; +device_platform_driver(bcm2835_rng_driver); + +MODULE_AUTHOR("Lubomir Rintel <lkundrak@v3.sk>"); +MODULE_DESCRIPTION("BCM2835 Random Number Generator (RNG) driver"); +MODULE_LICENSE("GPL v2"); |