diff options
Diffstat (limited to 'drivers/char/hw_random/mxc-rnga.c')
| -rw-r--r-- | drivers/char/hw_random/mxc-rnga.c | 217 |
1 files changed, 217 insertions, 0 deletions
diff --git a/drivers/char/hw_random/mxc-rnga.c b/drivers/char/hw_random/mxc-rnga.c new file mode 100644 index 000000000..6cbb72ec6 --- /dev/null +++ b/drivers/char/hw_random/mxc-rnga.c @@ -0,0 +1,217 @@ +/* + * RNG driver for Freescale RNGA + * + * Copyright 2008-2009 Freescale Semiconductor, Inc. All Rights Reserved. + * Author: Alan Carvalho de Assis <acassis@gmail.com> + */ + +/* + * 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 + * + * This driver is based on other RNG drivers. + */ + +#include <linux/module.h> +#include <linux/init.h> +#include <linux/kernel.h> +#include <linux/clk.h> +#include <linux/err.h> +#include <linux/ioport.h> +#include <linux/platform_device.h> +#include <linux/hw_random.h> +#include <linux/delay.h> +#include <linux/io.h> + +/* RNGA Registers */ +#define RNGA_CONTROL 0x00 +#define RNGA_STATUS 0x04 +#define RNGA_ENTROPY 0x08 +#define RNGA_OUTPUT_FIFO 0x0c +#define RNGA_MODE 0x10 +#define RNGA_VERIFICATION_CONTROL 0x14 +#define RNGA_OSC_CONTROL_COUNTER 0x18 +#define RNGA_OSC1_COUNTER 0x1c +#define RNGA_OSC2_COUNTER 0x20 +#define RNGA_OSC_COUNTER_STATUS 0x24 + +/* RNGA Registers Range */ +#define RNG_ADDR_RANGE 0x28 + +/* RNGA Control Register */ +#define RNGA_CONTROL_SLEEP 0x00000010 +#define RNGA_CONTROL_CLEAR_INT 0x00000008 +#define RNGA_CONTROL_MASK_INTS 0x00000004 +#define RNGA_CONTROL_HIGH_ASSURANCE 0x00000002 +#define RNGA_CONTROL_GO 0x00000001 + +#define RNGA_STATUS_LEVEL_MASK 0x0000ff00 + +/* RNGA Status Register */ +#define RNGA_STATUS_OSC_DEAD 0x80000000 +#define RNGA_STATUS_SLEEP 0x00000010 +#define RNGA_STATUS_ERROR_INT 0x00000008 +#define RNGA_STATUS_FIFO_UNDERFLOW 0x00000004 +#define RNGA_STATUS_LAST_READ_STATUS 0x00000002 +#define RNGA_STATUS_SECURITY_VIOLATION 0x00000001 + +struct mxc_rng { + struct device *dev; + struct hwrng rng; + void __iomem *mem; + struct clk *clk; +}; + +static int mxc_rnga_data_present(struct hwrng *rng, int wait) +{ + int i; + struct mxc_rng *mxc_rng = container_of(rng, struct mxc_rng, rng); + + for (i = 0; i < 20; i++) { + /* how many random numbers are in FIFO? [0-16] */ + int level = (__raw_readl(mxc_rng->mem + RNGA_STATUS) & + RNGA_STATUS_LEVEL_MASK) >> 8; + if (level || !wait) + return !!level; + udelay(10); + } + return 0; +} + +static int mxc_rnga_data_read(struct hwrng *rng, u32 * data) +{ + int err; + u32 ctrl; + struct mxc_rng *mxc_rng = container_of(rng, struct mxc_rng, rng); + + /* retrieve a random number from FIFO */ + *data = __raw_readl(mxc_rng->mem + RNGA_OUTPUT_FIFO); + + /* some error while reading this random number? */ + err = __raw_readl(mxc_rng->mem + RNGA_STATUS) & RNGA_STATUS_ERROR_INT; + + /* if error: clear error interrupt, but doesn't return random number */ + if (err) { + dev_dbg(mxc_rng->dev, "Error while reading random number!\n"); + ctrl = __raw_readl(mxc_rng->mem + RNGA_CONTROL); + __raw_writel(ctrl | RNGA_CONTROL_CLEAR_INT, + mxc_rng->mem + RNGA_CONTROL); + return 0; + } else + return 4; +} + +static int mxc_rnga_init(struct hwrng *rng) +{ + u32 ctrl, osc; + struct mxc_rng *mxc_rng = container_of(rng, struct mxc_rng, rng); + + /* wake up */ + ctrl = __raw_readl(mxc_rng->mem + RNGA_CONTROL); + __raw_writel(ctrl & ~RNGA_CONTROL_SLEEP, mxc_rng->mem + RNGA_CONTROL); + + /* verify if oscillator is working */ + osc = __raw_readl(mxc_rng->mem + RNGA_STATUS); + if (osc & RNGA_STATUS_OSC_DEAD) { + dev_err(mxc_rng->dev, "RNGA Oscillator is dead!\n"); + return -ENODEV; + } + + /* go running */ + ctrl = __raw_readl(mxc_rng->mem + RNGA_CONTROL); + __raw_writel(ctrl | RNGA_CONTROL_GO, mxc_rng->mem + RNGA_CONTROL); + + return 0; +} + +static void mxc_rnga_cleanup(struct hwrng *rng) +{ + u32 ctrl; + struct mxc_rng *mxc_rng = container_of(rng, struct mxc_rng, rng); + + ctrl = __raw_readl(mxc_rng->mem + RNGA_CONTROL); + + /* stop rnga */ + __raw_writel(ctrl & ~RNGA_CONTROL_GO, mxc_rng->mem + RNGA_CONTROL); +} + +static int __init mxc_rnga_probe(struct platform_device *pdev) +{ + int err = -ENODEV; + struct resource *res; + struct mxc_rng *mxc_rng; + + mxc_rng = devm_kzalloc(&pdev->dev, sizeof(struct mxc_rng), + GFP_KERNEL); + if (!mxc_rng) + return -ENOMEM; + + mxc_rng->dev = &pdev->dev; + mxc_rng->rng.name = "mxc-rnga"; + mxc_rng->rng.init = mxc_rnga_init; + mxc_rng->rng.cleanup = mxc_rnga_cleanup, + mxc_rng->rng.data_present = mxc_rnga_data_present, + mxc_rng->rng.data_read = mxc_rnga_data_read, + + mxc_rng->clk = devm_clk_get(&pdev->dev, NULL); + if (IS_ERR(mxc_rng->clk)) { + dev_err(&pdev->dev, "Could not get rng_clk!\n"); + err = PTR_ERR(mxc_rng->clk); + goto out; + } + + err = clk_prepare_enable(mxc_rng->clk); + if (err) + goto out; + + res = platform_get_resource(pdev, IORESOURCE_MEM, 0); + mxc_rng->mem = devm_ioremap_resource(&pdev->dev, res); + if (IS_ERR(mxc_rng->mem)) { + err = PTR_ERR(mxc_rng->mem); + goto err_ioremap; + } + + err = hwrng_register(&mxc_rng->rng); + if (err) { + dev_err(&pdev->dev, "MXC RNGA registering failed (%d)\n", err); + goto err_ioremap; + } + + dev_info(&pdev->dev, "MXC RNGA Registered.\n"); + + return 0; + +err_ioremap: + clk_disable_unprepare(mxc_rng->clk); + +out: + return err; +} + +static int __exit mxc_rnga_remove(struct platform_device *pdev) +{ + struct mxc_rng *mxc_rng = platform_get_drvdata(pdev); + + hwrng_unregister(&mxc_rng->rng); + + clk_disable_unprepare(mxc_rng->clk); + + return 0; +} + +static struct platform_driver mxc_rnga_driver = { + .driver = { + .name = "mxc_rnga", + }, + .remove = __exit_p(mxc_rnga_remove), +}; + +module_platform_driver_probe(mxc_rnga_driver, mxc_rnga_probe); + +MODULE_AUTHOR("Freescale Semiconductor, Inc."); +MODULE_DESCRIPTION("H/W RNGA driver for i.MX"); +MODULE_LICENSE("GPL"); |