diff options
Diffstat (limited to 'drivers/char/hw_random/omap3-rom-rng.c')
| -rw-r--r-- | drivers/char/hw_random/omap3-rom-rng.c | 155 |
1 files changed, 155 insertions, 0 deletions
diff --git a/drivers/char/hw_random/omap3-rom-rng.c b/drivers/char/hw_random/omap3-rom-rng.c new file mode 100644 index 000000000..8df3cad7c --- /dev/null +++ b/drivers/char/hw_random/omap3-rom-rng.c @@ -0,0 +1,155 @@ +/* + * omap3-rom-rng.c - RNG driver for TI OMAP3 CPU family + * + * Copyright (C) 2009 Nokia Corporation + * Author: Juha Yrjola <juha.yrjola@solidboot.com> + * + * Copyright (C) 2013 Pali Rohár <pali.rohar@gmail.com> + * + * This file is licensed under the terms of the GNU General Public + * License version 2. This program is licensed "as is" without any + * warranty of any kind, whether express or implied. + */ + +#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt + +#include <linux/module.h> +#include <linux/init.h> +#include <linux/random.h> +#include <linux/hw_random.h> +#include <linux/workqueue.h> +#include <linux/clk.h> +#include <linux/err.h> +#include <linux/of.h> +#include <linux/of_device.h> +#include <linux/platform_device.h> + +#define RNG_RESET 0x01 +#define RNG_GEN_PRNG_HW_INIT 0x02 +#define RNG_GEN_HW 0x08 + +/* param1: ptr, param2: count, param3: flag */ +static u32 (*omap3_rom_rng_call)(u32, u32, u32); + +static struct delayed_work idle_work; +static int rng_idle; +static struct clk *rng_clk; + +static void omap3_rom_rng_idle(struct work_struct *work) +{ + int r; + + r = omap3_rom_rng_call(0, 0, RNG_RESET); + if (r != 0) { + pr_err("reset failed: %d\n", r); + return; + } + clk_disable_unprepare(rng_clk); + rng_idle = 1; +} + +static int omap3_rom_rng_get_random(void *buf, unsigned int count) +{ + u32 r; + u32 ptr; + + cancel_delayed_work_sync(&idle_work); + if (rng_idle) { + r = clk_prepare_enable(rng_clk); + if (r) + return r; + + r = omap3_rom_rng_call(0, 0, RNG_GEN_PRNG_HW_INIT); + if (r != 0) { + clk_disable_unprepare(rng_clk); + pr_err("HW init failed: %d\n", r); + return -EIO; + } + rng_idle = 0; + } + + ptr = virt_to_phys(buf); + r = omap3_rom_rng_call(ptr, count, RNG_GEN_HW); + schedule_delayed_work(&idle_work, msecs_to_jiffies(500)); + if (r != 0) + return -EINVAL; + return 0; +} + +static int omap3_rom_rng_read(struct hwrng *rng, void *data, size_t max, bool w) +{ + int r; + + r = omap3_rom_rng_get_random(data, 4); + if (r < 0) + return r; + return 4; +} + +static struct hwrng omap3_rom_rng_ops = { + .name = "omap3-rom", +}; + +static int omap3_rom_rng_probe(struct platform_device *pdev) +{ + int ret = 0; + + omap3_rom_rng_ops.read = of_device_get_match_data(&pdev->dev); + if (!omap3_rom_rng_ops.read) { + dev_err(&pdev->dev, "missing rom code handler\n"); + + return -ENODEV; + } + + omap3_rom_rng_call = pdev->dev.platform_data; + if (!omap3_rom_rng_call) { + pr_err("omap3_rom_rng_call is NULL\n"); + return -EINVAL; + } + + INIT_DELAYED_WORK(&idle_work, omap3_rom_rng_idle); + rng_clk = devm_clk_get(&pdev->dev, "ick"); + if (IS_ERR(rng_clk)) { + pr_err("unable to get RNG clock\n"); + return PTR_ERR(rng_clk); + } + + /* Leave the RNG in reset state. */ + ret = clk_prepare_enable(rng_clk); + if (ret) + return ret; + omap3_rom_rng_idle(0); + + return hwrng_register(&omap3_rom_rng_ops); +} + +static int omap3_rom_rng_remove(struct platform_device *pdev) +{ + cancel_delayed_work_sync(&idle_work); + hwrng_unregister(&omap3_rom_rng_ops); + if (!rng_idle) + clk_disable_unprepare(rng_clk); + return 0; +} + +static const struct of_device_id omap_rom_rng_match[] = { + { .compatible = "nokia,n900-rom-rng", .data = omap3_rom_rng_read, }, + { /* sentinel */ }, +}; +MODULE_DEVICE_TABLE(of, omap_rom_rng_match); + +static struct platform_driver omap3_rom_rng_driver = { + .driver = { + .name = "omap3-rom-rng", + .of_match_table = omap_rom_rng_match, + }, + .probe = omap3_rom_rng_probe, + .remove = omap3_rom_rng_remove, +}; + +module_platform_driver(omap3_rom_rng_driver); + +MODULE_ALIAS("platform:omap3-rom-rng"); +MODULE_AUTHOR("Juha Yrjola"); +MODULE_AUTHOR("Pali Rohár <pali.rohar@gmail.com>"); +MODULE_LICENSE("GPL"); |