// SPDX-License-Identifier: GPL-2.0-or-later /* * Copyright (c) 2015, Daniel Thompson */ #include <linux/clk.h> #include <linux/delay.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/of_address.h> #include <linux/platform_device.h> #include <linux/pm_runtime.h> #include <linux/reset.h> #include <linux/slab.h> #define RNG_CR … #define RNG_CR_RNGEN … #define RNG_CR_CED … #define RNG_CR_CONFIG1 … #define RNG_CR_NISTC … #define RNG_CR_CONFIG2 … #define RNG_CR_CLKDIV_SHIFT … #define RNG_CR_CLKDIV … #define RNG_CR_CONFIG3 … #define RNG_CR_CONDRST … #define RNG_CR_CONFLOCK … #define RNG_CR_ENTROPY_SRC_MASK … #define RNG_CR_CONFIG_MASK … #define RNG_SR … #define RNG_SR_DRDY … #define RNG_SR_CECS … #define RNG_SR_SECS … #define RNG_SR_CEIS … #define RNG_SR_SEIS … #define RNG_DR … #define RNG_NSCR … #define RNG_NSCR_MASK … #define RNG_HTCR … #define RNG_NB_RECOVER_TRIES … struct stm32_rng_data { … }; /** * struct stm32_rng_config - RNG configuration data * * @cr: RNG configuration. 0 means default hardware RNG configuration * @nscr: Noise sources control configuration. * @htcr: Health tests configuration. */ struct stm32_rng_config { … }; struct stm32_rng_private { … }; /* * Extracts from the STM32 RNG specification when RNG supports CONDRST. * * When a noise source (or seed) error occurs, the RNG stops generating * random numbers and sets to “1” both SEIS and SECS bits to indicate * that a seed error occurred. (...) * * 1. Software reset by writing CONDRST at 1 and at 0 (see bitfield * description for details). This step is needed only if SECS is set. * Indeed, when SEIS is set and SECS is cleared it means RNG performed * the reset automatically (auto-reset). * 2. If SECS was set in step 1 (no auto-reset) wait for CONDRST * to be cleared in the RNG_CR register, then confirm that SEIS is * cleared in the RNG_SR register. Otherwise just clear SEIS bit in * the RNG_SR register. * 3. If SECS was set in step 1 (no auto-reset) wait for SECS to be * cleared by RNG. The random number generation is now back to normal. */ static int stm32_rng_conceal_seed_error_cond_reset(struct stm32_rng_private *priv) { … } /* * Extracts from the STM32 RNG specification, when CONDRST is not supported * * When a noise source (or seed) error occurs, the RNG stops generating * random numbers and sets to “1” both SEIS and SECS bits to indicate * that a seed error occurred. (...) * * The following sequence shall be used to fully recover from a seed * error after the RNG initialization: * 1. Clear the SEIS bit by writing it to “0”. * 2. Read out 12 words from the RNG_DR register, and discard each of * them in order to clean the pipeline. * 3. Confirm that SEIS is still cleared. Random number generation is * back to normal. */ static int stm32_rng_conceal_seed_error_sw_reset(struct stm32_rng_private *priv) { … } static int stm32_rng_conceal_seed_error(struct hwrng *rng) { struct stm32_rng_private *priv = container_of(rng, struct stm32_rng_private, rng); dev_dbg(priv->dev, "Concealing seed error\n"); if (priv->data->has_cond_reset) return stm32_rng_conceal_seed_error_cond_reset(priv); else return stm32_rng_conceal_seed_error_sw_reset(priv); }; static int stm32_rng_read(struct hwrng *rng, void *data, size_t max, bool wait) { … } static uint stm32_rng_clock_freq_restrain(struct hwrng *rng) { … } static int stm32_rng_init(struct hwrng *rng) { … } static void stm32_rng_remove(struct platform_device *ofdev) { … } static int __maybe_unused stm32_rng_runtime_suspend(struct device *dev) { … } static int __maybe_unused stm32_rng_suspend(struct device *dev) { … } static int __maybe_unused stm32_rng_runtime_resume(struct device *dev) { … } static int __maybe_unused stm32_rng_resume(struct device *dev) { … } static const struct dev_pm_ops __maybe_unused stm32_rng_pm_ops = …; static const struct stm32_rng_data stm32mp13_rng_data = …; static const struct stm32_rng_data stm32_rng_data = …; static const struct of_device_id stm32_rng_match[] = …; MODULE_DEVICE_TABLE(of, stm32_rng_match); static int stm32_rng_probe(struct platform_device *ofdev) { … } static struct platform_driver stm32_rng_driver = …; module_platform_driver(…) …; MODULE_LICENSE(…) …; MODULE_AUTHOR(…) …; MODULE_DESCRIPTION(…) …;
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