diff options
Diffstat (limited to 'drivers/char/hw_random/iproc-rng200.c')
| -rw-r--r-- | drivers/char/hw_random/iproc-rng200.c | 239 |
1 files changed, 239 insertions, 0 deletions
diff --git a/drivers/char/hw_random/iproc-rng200.c b/drivers/char/hw_random/iproc-rng200.c new file mode 100644 index 000000000000..3eaf7cb96d36 --- /dev/null +++ b/drivers/char/hw_random/iproc-rng200.c @@ -0,0 +1,239 @@ +/* +* Copyright (C) 2015 Broadcom Corporation +* +* This program is free software; you can redistribute it and/or +* modify it under the terms of the GNU General Public License as +* published by the Free Software Foundation version 2. +* +* This program is distributed "as is" WITHOUT ANY WARRANTY of any +* kind, whether express or implied; without even the implied warranty +* of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the +* GNU General Public License for more details. +*/ +/* + * DESCRIPTION: The Broadcom iProc RNG200 Driver + */ + +#include <linux/hw_random.h> +#include <linux/init.h> +#include <linux/io.h> +#include <linux/kernel.h> +#include <linux/module.h> +#include <linux/of_address.h> +#include <linux/of_platform.h> +#include <linux/platform_device.h> +#include <linux/delay.h> + +/* Registers */ +#define RNG_CTRL_OFFSET 0x00 +#define RNG_CTRL_RNG_RBGEN_MASK 0x00001FFF +#define RNG_CTRL_RNG_RBGEN_ENABLE 0x00000001 +#define RNG_CTRL_RNG_RBGEN_DISABLE 0x00000000 + +#define RNG_SOFT_RESET_OFFSET 0x04 +#define RNG_SOFT_RESET 0x00000001 + +#define RBG_SOFT_RESET_OFFSET 0x08 +#define RBG_SOFT_RESET 0x00000001 + +#define RNG_INT_STATUS_OFFSET 0x18 +#define RNG_INT_STATUS_MASTER_FAIL_LOCKOUT_IRQ_MASK 0x80000000 +#define RNG_INT_STATUS_STARTUP_TRANSITIONS_MET_IRQ_MASK 0x00020000 +#define RNG_INT_STATUS_NIST_FAIL_IRQ_MASK 0x00000020 +#define RNG_INT_STATUS_TOTAL_BITS_COUNT_IRQ_MASK 0x00000001 + +#define RNG_FIFO_DATA_OFFSET 0x20 + +#define RNG_FIFO_COUNT_OFFSET 0x24 +#define RNG_FIFO_COUNT_RNG_FIFO_COUNT_MASK 0x000000FF + +struct iproc_rng200_dev { + struct hwrng rng; + void __iomem *base; +}; + +#define to_rng_priv(rng) container_of(rng, struct iproc_rng200_dev, rng) + +static void iproc_rng200_restart(void __iomem *rng_base) +{ + uint32_t val; + + /* Disable RBG */ + val = ioread32(rng_base + RNG_CTRL_OFFSET); + val &= ~RNG_CTRL_RNG_RBGEN_MASK; + val |= RNG_CTRL_RNG_RBGEN_DISABLE; + iowrite32(val, rng_base + RNG_CTRL_OFFSET); + + /* Clear all interrupt status */ + iowrite32(0xFFFFFFFFUL, rng_base + RNG_INT_STATUS_OFFSET); + + /* Reset RNG and RBG */ + val = ioread32(rng_base + RBG_SOFT_RESET_OFFSET); + val |= RBG_SOFT_RESET; + iowrite32(val, rng_base + RBG_SOFT_RESET_OFFSET); + + val = ioread32(rng_base + RNG_SOFT_RESET_OFFSET); + val |= RNG_SOFT_RESET; + iowrite32(val, rng_base + RNG_SOFT_RESET_OFFSET); + + val = ioread32(rng_base + RNG_SOFT_RESET_OFFSET); + val &= ~RNG_SOFT_RESET; + iowrite32(val, rng_base + RNG_SOFT_RESET_OFFSET); + + val = ioread32(rng_base + RBG_SOFT_RESET_OFFSET); + val &= ~RBG_SOFT_RESET; + iowrite32(val, rng_base + RBG_SOFT_RESET_OFFSET); + + /* Enable RBG */ + val = ioread32(rng_base + RNG_CTRL_OFFSET); + val &= ~RNG_CTRL_RNG_RBGEN_MASK; + val |= RNG_CTRL_RNG_RBGEN_ENABLE; + iowrite32(val, rng_base + RNG_CTRL_OFFSET); +} + +static int iproc_rng200_read(struct hwrng *rng, void *buf, size_t max, + bool wait) +{ + struct iproc_rng200_dev *priv = to_rng_priv(rng); + uint32_t num_remaining = max; + uint32_t status; + + #define MAX_RESETS_PER_READ 1 + uint32_t num_resets = 0; + + #define MAX_IDLE_TIME (1 * HZ) + unsigned long idle_endtime = jiffies + MAX_IDLE_TIME; + + while ((num_remaining > 0) && time_before(jiffies, idle_endtime)) { + + /* Is RNG sane? If not, reset it. */ + status = ioread32(priv->base + RNG_INT_STATUS_OFFSET); + if ((status & (RNG_INT_STATUS_MASTER_FAIL_LOCKOUT_IRQ_MASK | + RNG_INT_STATUS_NIST_FAIL_IRQ_MASK)) != 0) { + + if (num_resets >= MAX_RESETS_PER_READ) + return max - num_remaining; + + iproc_rng200_restart(priv->base); + num_resets++; + } + + /* Are there any random numbers available? */ + if ((ioread32(priv->base + RNG_FIFO_COUNT_OFFSET) & + RNG_FIFO_COUNT_RNG_FIFO_COUNT_MASK) > 0) { + + if (num_remaining >= sizeof(uint32_t)) { + /* Buffer has room to store entire word */ + *(uint32_t *)buf = ioread32(priv->base + + RNG_FIFO_DATA_OFFSET); + buf += sizeof(uint32_t); + num_remaining -= sizeof(uint32_t); + } else { + /* Buffer can only store partial word */ + uint32_t rnd_number = ioread32(priv->base + + RNG_FIFO_DATA_OFFSET); + memcpy(buf, &rnd_number, num_remaining); + buf += num_remaining; + num_remaining = 0; + } + + /* Reset the IDLE timeout */ + idle_endtime = jiffies + MAX_IDLE_TIME; + } else { + if (!wait) + /* Cannot wait, return immediately */ + return max - num_remaining; + + /* Can wait, give others chance to run */ + usleep_range(min(num_remaining * 10, 500U), 500); + } + } + + return max - num_remaining; +} + +static int iproc_rng200_init(struct hwrng *rng) +{ + struct iproc_rng200_dev *priv = to_rng_priv(rng); + uint32_t val; + + /* Setup RNG. */ + val = ioread32(priv->base + RNG_CTRL_OFFSET); + val &= ~RNG_CTRL_RNG_RBGEN_MASK; + val |= RNG_CTRL_RNG_RBGEN_ENABLE; + iowrite32(val, priv->base + RNG_CTRL_OFFSET); + + return 0; +} + +static void iproc_rng200_cleanup(struct hwrng *rng) +{ + struct iproc_rng200_dev *priv = to_rng_priv(rng); + uint32_t val; + + /* Disable RNG hardware */ + val = ioread32(priv->base + RNG_CTRL_OFFSET); + val &= ~RNG_CTRL_RNG_RBGEN_MASK; + val |= RNG_CTRL_RNG_RBGEN_DISABLE; + iowrite32(val, priv->base + RNG_CTRL_OFFSET); +} + +static int iproc_rng200_probe(struct platform_device *pdev) +{ + struct iproc_rng200_dev *priv; + struct resource *res; + struct device *dev = &pdev->dev; + int ret; + + priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL); + if (!priv) + return -ENOMEM; + + /* Map peripheral */ + res = platform_get_resource(pdev, IORESOURCE_MEM, 0); + if (!res) { + dev_err(dev, "failed to get rng resources\n"); + return -EINVAL; + } + + priv->base = devm_ioremap_resource(dev, res); + if (IS_ERR(priv->base)) { + dev_err(dev, "failed to remap rng regs\n"); + return PTR_ERR(priv->base); + } + + priv->rng.name = "iproc-rng200", + priv->rng.read = iproc_rng200_read, + priv->rng.init = iproc_rng200_init, + priv->rng.cleanup = iproc_rng200_cleanup, + + /* Register driver */ + ret = devm_hwrng_register(dev, &priv->rng); + if (ret) { + dev_err(dev, "hwrng registration failed\n"); + return ret; + } + + dev_info(dev, "hwrng registered\n"); + + return 0; +} + +static const struct of_device_id iproc_rng200_of_match[] = { + { .compatible = "brcm,iproc-rng200", }, + {}, +}; +MODULE_DEVICE_TABLE(of, iproc_rng200_of_match); + +static struct platform_driver iproc_rng200_driver = { + .driver = { + .name = "iproc-rng200", + .of_match_table = iproc_rng200_of_match, + }, + .probe = iproc_rng200_probe, +}; +module_platform_driver(iproc_rng200_driver); + +MODULE_AUTHOR("Broadcom"); +MODULE_DESCRIPTION("iProc RNG200 Random Number Generator driver"); +MODULE_LICENSE("GPL v2"); |