diff options
Diffstat (limited to 'drivers/char/hw_random/rockchip-rng.c')
| -rw-r--r-- | drivers/char/hw_random/rockchip-rng.c | 228 |
1 files changed, 228 insertions, 0 deletions
diff --git a/drivers/char/hw_random/rockchip-rng.c b/drivers/char/hw_random/rockchip-rng.c new file mode 100644 index 000000000000..289b385bbf05 --- /dev/null +++ b/drivers/char/hw_random/rockchip-rng.c @@ -0,0 +1,228 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * rockchip-rng.c True Random Number Generator driver for Rockchip RK3568 SoC + * + * Copyright (c) 2018, Fuzhou Rockchip Electronics Co., Ltd. + * Copyright (c) 2022, Aurelien Jarno + * Authors: + * Lin Jinhan <troy.lin@rock-chips.com> + * Aurelien Jarno <aurelien@aurel32.net> + */ +#include <linux/clk.h> +#include <linux/hw_random.h> +#include <linux/io.h> +#include <linux/iopoll.h> +#include <linux/kernel.h> +#include <linux/module.h> +#include <linux/of.h> +#include <linux/platform_device.h> +#include <linux/pm_runtime.h> +#include <linux/reset.h> +#include <linux/slab.h> + +#define RK_RNG_AUTOSUSPEND_DELAY 100 +#define RK_RNG_MAX_BYTE 32 +#define RK_RNG_POLL_PERIOD_US 100 +#define RK_RNG_POLL_TIMEOUT_US 10000 + +/* + * TRNG collects osc ring output bit every RK_RNG_SAMPLE_CNT time. The value is + * a tradeoff between speed and quality and has been adjusted to get a quality + * of ~900 (~87.5% of FIPS 140-2 successes). + */ +#define RK_RNG_SAMPLE_CNT 1000 + +/* TRNG registers from RK3568 TRM-Part2, section 5.4.1 */ +#define TRNG_RST_CTL 0x0004 +#define TRNG_RNG_CTL 0x0400 +#define TRNG_RNG_CTL_LEN_64_BIT (0x00 << 4) +#define TRNG_RNG_CTL_LEN_128_BIT (0x01 << 4) +#define TRNG_RNG_CTL_LEN_192_BIT (0x02 << 4) +#define TRNG_RNG_CTL_LEN_256_BIT (0x03 << 4) +#define TRNG_RNG_CTL_OSC_RING_SPEED_0 (0x00 << 2) +#define TRNG_RNG_CTL_OSC_RING_SPEED_1 (0x01 << 2) +#define TRNG_RNG_CTL_OSC_RING_SPEED_2 (0x02 << 2) +#define TRNG_RNG_CTL_OSC_RING_SPEED_3 (0x03 << 2) +#define TRNG_RNG_CTL_MASK GENMASK(15, 0) +#define TRNG_RNG_CTL_ENABLE BIT(1) +#define TRNG_RNG_CTL_START BIT(0) +#define TRNG_RNG_SAMPLE_CNT 0x0404 +#define TRNG_RNG_DOUT 0x0410 + +struct rk_rng { + struct hwrng rng; + void __iomem *base; + int clk_num; + struct clk_bulk_data *clk_bulks; +}; + +/* The mask in the upper 16 bits determines the bits that are updated */ +static void rk_rng_write_ctl(struct rk_rng *rng, u32 val, u32 mask) +{ + writel((mask << 16) | val, rng->base + TRNG_RNG_CTL); +} + +static int rk_rng_init(struct hwrng *rng) +{ + struct rk_rng *rk_rng = container_of(rng, struct rk_rng, rng); + int ret; + + /* start clocks */ + ret = clk_bulk_prepare_enable(rk_rng->clk_num, rk_rng->clk_bulks); + if (ret < 0) { + dev_err((struct device *) rk_rng->rng.priv, + "Failed to enable clks %d\n", ret); + return ret; + } + + /* set the sample period */ + writel(RK_RNG_SAMPLE_CNT, rk_rng->base + TRNG_RNG_SAMPLE_CNT); + + /* set osc ring speed and enable it */ + rk_rng_write_ctl(rk_rng, TRNG_RNG_CTL_LEN_256_BIT | + TRNG_RNG_CTL_OSC_RING_SPEED_0 | + TRNG_RNG_CTL_ENABLE, + TRNG_RNG_CTL_MASK); + + return 0; +} + +static void rk_rng_cleanup(struct hwrng *rng) +{ + struct rk_rng *rk_rng = container_of(rng, struct rk_rng, rng); + + /* stop TRNG */ + rk_rng_write_ctl(rk_rng, 0, TRNG_RNG_CTL_MASK); + + /* stop clocks */ + clk_bulk_disable_unprepare(rk_rng->clk_num, rk_rng->clk_bulks); +} + +static int rk_rng_read(struct hwrng *rng, void *buf, size_t max, bool wait) +{ + struct rk_rng *rk_rng = container_of(rng, struct rk_rng, rng); + size_t to_read = min_t(size_t, max, RK_RNG_MAX_BYTE); + u32 reg; + int ret = 0; + + ret = pm_runtime_resume_and_get((struct device *) rk_rng->rng.priv); + if (ret < 0) + return ret; + + /* Start collecting random data */ + rk_rng_write_ctl(rk_rng, TRNG_RNG_CTL_START, TRNG_RNG_CTL_START); + + ret = readl_poll_timeout(rk_rng->base + TRNG_RNG_CTL, reg, + !(reg & TRNG_RNG_CTL_START), + RK_RNG_POLL_PERIOD_US, + RK_RNG_POLL_TIMEOUT_US); + if (ret < 0) + goto out; + + /* Read random data stored in the registers */ + memcpy_fromio(buf, rk_rng->base + TRNG_RNG_DOUT, to_read); +out: + pm_runtime_mark_last_busy((struct device *) rk_rng->rng.priv); + pm_runtime_put_sync_autosuspend((struct device *) rk_rng->rng.priv); + + return (ret < 0) ? ret : to_read; +} + +static int rk_rng_probe(struct platform_device *pdev) +{ + struct device *dev = &pdev->dev; + struct reset_control *rst; + struct rk_rng *rk_rng; + int ret; + + rk_rng = devm_kzalloc(dev, sizeof(*rk_rng), GFP_KERNEL); + if (!rk_rng) + return -ENOMEM; + + rk_rng->base = devm_platform_ioremap_resource(pdev, 0); + if (IS_ERR(rk_rng->base)) + return PTR_ERR(rk_rng->base); + + rk_rng->clk_num = devm_clk_bulk_get_all(dev, &rk_rng->clk_bulks); + if (rk_rng->clk_num < 0) + return dev_err_probe(dev, rk_rng->clk_num, + "Failed to get clks property\n"); + + rst = devm_reset_control_array_get_exclusive(&pdev->dev); + if (IS_ERR(rst)) + return dev_err_probe(dev, PTR_ERR(rst), "Failed to get reset property\n"); + + reset_control_assert(rst); + udelay(2); + reset_control_deassert(rst); + + platform_set_drvdata(pdev, rk_rng); + + rk_rng->rng.name = dev_driver_string(dev); + if (!IS_ENABLED(CONFIG_PM)) { + rk_rng->rng.init = rk_rng_init; + rk_rng->rng.cleanup = rk_rng_cleanup; + } + rk_rng->rng.read = rk_rng_read; + rk_rng->rng.priv = (unsigned long) dev; + rk_rng->rng.quality = 900; + + pm_runtime_set_autosuspend_delay(dev, RK_RNG_AUTOSUSPEND_DELAY); + pm_runtime_use_autosuspend(dev); + ret = devm_pm_runtime_enable(dev); + if (ret) + return dev_err_probe(&pdev->dev, ret, "Runtime pm activation failed.\n"); + + ret = devm_hwrng_register(dev, &rk_rng->rng); + if (ret) + return dev_err_probe(&pdev->dev, ret, "Failed to register Rockchip hwrng\n"); + + return 0; +} + +static int __maybe_unused rk_rng_runtime_suspend(struct device *dev) +{ + struct rk_rng *rk_rng = dev_get_drvdata(dev); + + rk_rng_cleanup(&rk_rng->rng); + + return 0; +} + +static int __maybe_unused rk_rng_runtime_resume(struct device *dev) +{ + struct rk_rng *rk_rng = dev_get_drvdata(dev); + + return rk_rng_init(&rk_rng->rng); +} + +static const struct dev_pm_ops rk_rng_pm_ops = { + SET_RUNTIME_PM_OPS(rk_rng_runtime_suspend, + rk_rng_runtime_resume, NULL) + SET_SYSTEM_SLEEP_PM_OPS(pm_runtime_force_suspend, + pm_runtime_force_resume) +}; + +static const struct of_device_id rk_rng_dt_match[] = { + { .compatible = "rockchip,rk3568-rng", }, + { /* sentinel */ }, +}; + +MODULE_DEVICE_TABLE(of, rk_rng_dt_match); + +static struct platform_driver rk_rng_driver = { + .driver = { + .name = "rockchip-rng", + .pm = &rk_rng_pm_ops, + .of_match_table = rk_rng_dt_match, + }, + .probe = rk_rng_probe, +}; + +module_platform_driver(rk_rng_driver); + +MODULE_DESCRIPTION("Rockchip RK3568 True Random Number Generator driver"); +MODULE_AUTHOR("Lin Jinhan <troy.lin@rock-chips.com>"); +MODULE_AUTHOR("Aurelien Jarno <aurelien@aurel32.net>"); +MODULE_AUTHOR("Daniel Golle <daniel@makrotopia.org>"); +MODULE_LICENSE("GPL"); |