diff options
Diffstat (limited to 'drivers/char/hw_random/stm32-rng.c')
| -rw-r--r-- | drivers/char/hw_random/stm32-rng.c | 512 |
1 files changed, 429 insertions, 83 deletions
diff --git a/drivers/char/hw_random/stm32-rng.c b/drivers/char/hw_random/stm32-rng.c index efb6a9f9a1..efd6edcd70 100644 --- a/drivers/char/hw_random/stm32-rng.c +++ b/drivers/char/hw_random/stm32-rng.c @@ -17,60 +17,234 @@ #include <linux/reset.h> #include <linux/slab.h> -#define RNG_CR 0x00 -#define RNG_CR_RNGEN BIT(2) -#define RNG_CR_CED BIT(5) - -#define RNG_SR 0x04 -#define RNG_SR_SEIS BIT(6) -#define RNG_SR_CEIS BIT(5) -#define RNG_SR_DRDY BIT(0) +#define RNG_CR 0x00 +#define RNG_CR_RNGEN BIT(2) +#define RNG_CR_CED BIT(5) +#define RNG_CR_CONFIG1 GENMASK(11, 8) +#define RNG_CR_NISTC BIT(12) +#define RNG_CR_CONFIG2 GENMASK(15, 13) +#define RNG_CR_CLKDIV_SHIFT 16 +#define RNG_CR_CLKDIV GENMASK(19, 16) +#define RNG_CR_CONFIG3 GENMASK(25, 20) +#define RNG_CR_CONDRST BIT(30) +#define RNG_CR_CONFLOCK BIT(31) +#define RNG_CR_ENTROPY_SRC_MASK (RNG_CR_CONFIG1 | RNG_CR_NISTC | RNG_CR_CONFIG2 | RNG_CR_CONFIG3) +#define RNG_CR_CONFIG_MASK (RNG_CR_ENTROPY_SRC_MASK | RNG_CR_CED | RNG_CR_CLKDIV) + +#define RNG_SR 0x04 +#define RNG_SR_DRDY BIT(0) +#define RNG_SR_CECS BIT(1) +#define RNG_SR_SECS BIT(2) +#define RNG_SR_CEIS BIT(5) +#define RNG_SR_SEIS BIT(6) + +#define RNG_DR 0x08 + +#define RNG_NSCR 0x0C +#define RNG_NSCR_MASK GENMASK(17, 0) + +#define RNG_HTCR 0x10 + +#define RNG_NB_RECOVER_TRIES 3 + +struct stm32_rng_data { + uint max_clock_rate; + u32 cr; + u32 nscr; + u32 htcr; + bool has_cond_reset; +}; -#define RNG_DR 0x08 +/** + * 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 { + u32 cr; + u32 nscr; + u32 htcr; +}; struct stm32_rng_private { struct hwrng rng; void __iomem *base; struct clk *clk; struct reset_control *rst; + struct stm32_rng_config pm_conf; + const struct stm32_rng_data *data; bool ced; + bool lock_conf; }; +/* + * 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) +{ + struct device *dev = (struct device *)priv->rng.priv; + u32 sr = readl_relaxed(priv->base + RNG_SR); + u32 cr = readl_relaxed(priv->base + RNG_CR); + int err; + + if (sr & RNG_SR_SECS) { + /* Conceal by resetting the subsystem (step 1.) */ + writel_relaxed(cr | RNG_CR_CONDRST, priv->base + RNG_CR); + writel_relaxed(cr & ~RNG_CR_CONDRST, priv->base + RNG_CR); + } else { + /* RNG auto-reset (step 2.) */ + writel_relaxed(sr & ~RNG_SR_SEIS, priv->base + RNG_SR); + goto end; + } + + err = readl_relaxed_poll_timeout_atomic(priv->base + RNG_CR, cr, !(cr & RNG_CR_CONDRST), 10, + 100000); + if (err) { + dev_err(dev, "%s: timeout %x\n", __func__, sr); + return err; + } + + /* Check SEIS is cleared (step 2.) */ + if (readl_relaxed(priv->base + RNG_SR) & RNG_SR_SEIS) + return -EINVAL; + + err = readl_relaxed_poll_timeout_atomic(priv->base + RNG_SR, sr, !(sr & RNG_SR_SECS), 10, + 100000); + if (err) { + dev_err(dev, "%s: timeout %x\n", __func__, sr); + return err; + } + +end: + return 0; +} + +/* + * 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) +{ + unsigned int i = 0; + u32 sr = readl_relaxed(priv->base + RNG_SR); + + writel_relaxed(sr & ~RNG_SR_SEIS, priv->base + RNG_SR); + + for (i = 12; i != 0; i--) + (void)readl_relaxed(priv->base + RNG_DR); + + if (readl_relaxed(priv->base + RNG_SR) & RNG_SR_SEIS) + return -EINVAL; + + return 0; +} + +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((struct device *)priv->rng.priv, "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) { - struct stm32_rng_private *priv = - container_of(rng, struct stm32_rng_private, rng); + struct stm32_rng_private *priv = container_of(rng, struct stm32_rng_private, rng); + unsigned int i = 0; + int retval = 0, err = 0; u32 sr; - int retval = 0; pm_runtime_get_sync((struct device *) priv->rng.priv); + if (readl_relaxed(priv->base + RNG_SR) & RNG_SR_SEIS) + stm32_rng_conceal_seed_error(rng); + while (max >= sizeof(u32)) { sr = readl_relaxed(priv->base + RNG_SR); - /* Manage timeout which is based on timer and take */ - /* care of initial delay time when enabling rng */ + /* + * Manage timeout which is based on timer and take + * care of initial delay time when enabling the RNG. + */ if (!sr && wait) { - int err; - err = readl_relaxed_poll_timeout_atomic(priv->base + RNG_SR, sr, sr, 10, 50000); - if (err) + if (err) { dev_err((struct device *)priv->rng.priv, "%s: timeout %x!\n", __func__, sr); + break; + } + } else if (!sr) { + /* The FIFO is being filled up */ + break; } - /* If error detected or data not ready... */ if (sr != RNG_SR_DRDY) { - if (WARN_ONCE(sr & (RNG_SR_SEIS | RNG_SR_CEIS), - "bad RNG status - %x\n", sr)) + if (sr & RNG_SR_SEIS) { + err = stm32_rng_conceal_seed_error(rng); + i++; + if (err && i > RNG_NB_RECOVER_TRIES) { + dev_err((struct device *)priv->rng.priv, + "Couldn't recover from seed error\n"); + return -ENOTRECOVERABLE; + } + + continue; + } + + if (WARN_ONCE((sr & RNG_SR_CEIS), "RNG clock too slow - %x\n", sr)) writel_relaxed(0, priv->base + RNG_SR); - break; } + /* Late seed error case: DR being 0 is an error status */ *(u32 *)data = readl_relaxed(priv->base + RNG_DR); + if (!*(u32 *)data) { + err = stm32_rng_conceal_seed_error(rng); + i++; + if (err && i > RNG_NB_RECOVER_TRIES) { + dev_err((struct device *)priv->rng.priv, + "Couldn't recover from seed error"); + return -ENOTRECOVERABLE; + } + continue; + } + + i = 0; retval += sizeof(u32); data += sizeof(u32); max -= sizeof(u32); @@ -82,54 +256,265 @@ static int stm32_rng_read(struct hwrng *rng, void *data, size_t max, bool wait) return retval || !wait ? retval : -EIO; } +static uint stm32_rng_clock_freq_restrain(struct hwrng *rng) +{ + struct stm32_rng_private *priv = + container_of(rng, struct stm32_rng_private, rng); + unsigned long clock_rate = 0; + uint clock_div = 0; + + clock_rate = clk_get_rate(priv->clk); + + /* + * Get the exponent to apply on the CLKDIV field in RNG_CR register + * No need to handle the case when clock-div > 0xF as it is physically + * impossible + */ + while ((clock_rate >> clock_div) > priv->data->max_clock_rate) + clock_div++; + + pr_debug("RNG clk rate : %lu\n", clk_get_rate(priv->clk) >> clock_div); + + return clock_div; +} + static int stm32_rng_init(struct hwrng *rng) { struct stm32_rng_private *priv = container_of(rng, struct stm32_rng_private, rng); int err; + u32 reg; err = clk_prepare_enable(priv->clk); if (err) return err; - if (priv->ced) - writel_relaxed(RNG_CR_RNGEN, priv->base + RNG_CR); - else - writel_relaxed(RNG_CR_RNGEN | RNG_CR_CED, - priv->base + RNG_CR); - /* clear error indicators */ writel_relaxed(0, priv->base + RNG_SR); + reg = readl_relaxed(priv->base + RNG_CR); + + /* + * Keep default RNG configuration if none was specified. + * 0 is an invalid value as it disables all entropy sources. + */ + if (priv->data->has_cond_reset && priv->data->cr) { + uint clock_div = stm32_rng_clock_freq_restrain(rng); + + reg &= ~RNG_CR_CONFIG_MASK; + reg |= RNG_CR_CONDRST | (priv->data->cr & RNG_CR_ENTROPY_SRC_MASK) | + (clock_div << RNG_CR_CLKDIV_SHIFT); + if (priv->ced) + reg &= ~RNG_CR_CED; + else + reg |= RNG_CR_CED; + writel_relaxed(reg, priv->base + RNG_CR); + + /* Health tests and noise control registers */ + writel_relaxed(priv->data->htcr, priv->base + RNG_HTCR); + writel_relaxed(priv->data->nscr & RNG_NSCR_MASK, priv->base + RNG_NSCR); + + reg &= ~RNG_CR_CONDRST; + reg |= RNG_CR_RNGEN; + if (priv->lock_conf) + reg |= RNG_CR_CONFLOCK; + + writel_relaxed(reg, priv->base + RNG_CR); + + err = readl_relaxed_poll_timeout_atomic(priv->base + RNG_CR, reg, + (!(reg & RNG_CR_CONDRST)), + 10, 50000); + if (err) { + clk_disable_unprepare(priv->clk); + dev_err((struct device *)priv->rng.priv, + "%s: timeout %x!\n", __func__, reg); + return -EINVAL; + } + } else { + /* Handle all RNG versions by checking if conditional reset should be set */ + if (priv->data->has_cond_reset) + reg |= RNG_CR_CONDRST; + + if (priv->ced) + reg &= ~RNG_CR_CED; + else + reg |= RNG_CR_CED; + + writel_relaxed(reg, priv->base + RNG_CR); + + if (priv->data->has_cond_reset) + reg &= ~RNG_CR_CONDRST; + + reg |= RNG_CR_RNGEN; + + writel_relaxed(reg, priv->base + RNG_CR); + } + + err = readl_relaxed_poll_timeout_atomic(priv->base + RNG_SR, reg, + reg & RNG_SR_DRDY, + 10, 100000); + if (err | (reg & ~RNG_SR_DRDY)) { + clk_disable_unprepare(priv->clk); + dev_err((struct device *)priv->rng.priv, + "%s: timeout:%x SR: %x!\n", __func__, err, reg); + return -EINVAL; + } + return 0; } -static void stm32_rng_cleanup(struct hwrng *rng) +static int stm32_rng_remove(struct platform_device *ofdev) { - struct stm32_rng_private *priv = - container_of(rng, struct stm32_rng_private, rng); + pm_runtime_disable(&ofdev->dev); + + return 0; +} + +static int __maybe_unused stm32_rng_runtime_suspend(struct device *dev) +{ + struct stm32_rng_private *priv = dev_get_drvdata(dev); + u32 reg; - writel_relaxed(0, priv->base + RNG_CR); + reg = readl_relaxed(priv->base + RNG_CR); + reg &= ~RNG_CR_RNGEN; + writel_relaxed(reg, priv->base + RNG_CR); clk_disable_unprepare(priv->clk); + + return 0; } +static int __maybe_unused stm32_rng_suspend(struct device *dev) +{ + struct stm32_rng_private *priv = dev_get_drvdata(dev); + + if (priv->data->has_cond_reset) { + priv->pm_conf.nscr = readl_relaxed(priv->base + RNG_NSCR); + priv->pm_conf.htcr = readl_relaxed(priv->base + RNG_HTCR); + } + + /* Do not save that RNG is enabled as it will be handled at resume */ + priv->pm_conf.cr = readl_relaxed(priv->base + RNG_CR) & ~RNG_CR_RNGEN; + + writel_relaxed(priv->pm_conf.cr, priv->base + RNG_CR); + + clk_disable_unprepare(priv->clk); + + return 0; +} + +static int __maybe_unused stm32_rng_runtime_resume(struct device *dev) +{ + struct stm32_rng_private *priv = dev_get_drvdata(dev); + int err; + u32 reg; + + err = clk_prepare_enable(priv->clk); + if (err) + return err; + + /* Clean error indications */ + writel_relaxed(0, priv->base + RNG_SR); + + reg = readl_relaxed(priv->base + RNG_CR); + reg |= RNG_CR_RNGEN; + writel_relaxed(reg, priv->base + RNG_CR); + + return 0; +} + +static int __maybe_unused stm32_rng_resume(struct device *dev) +{ + struct stm32_rng_private *priv = dev_get_drvdata(dev); + int err; + u32 reg; + + err = clk_prepare_enable(priv->clk); + if (err) + return err; + + /* Clean error indications */ + writel_relaxed(0, priv->base + RNG_SR); + + if (priv->data->has_cond_reset) { + /* + * Correct configuration in bits [29:4] must be set in the same + * access that set RNG_CR_CONDRST bit. Else config setting is + * not taken into account. CONFIGLOCK bit must also be unset but + * it is not handled at the moment. + */ + writel_relaxed(priv->pm_conf.cr | RNG_CR_CONDRST, priv->base + RNG_CR); + + writel_relaxed(priv->pm_conf.nscr, priv->base + RNG_NSCR); + writel_relaxed(priv->pm_conf.htcr, priv->base + RNG_HTCR); + + reg = readl_relaxed(priv->base + RNG_CR); + reg |= RNG_CR_RNGEN; + reg &= ~RNG_CR_CONDRST; + writel_relaxed(reg, priv->base + RNG_CR); + + err = readl_relaxed_poll_timeout_atomic(priv->base + RNG_CR, reg, + reg & ~RNG_CR_CONDRST, 10, 100000); + + if (err) { + clk_disable_unprepare(priv->clk); + dev_err((struct device *)priv->rng.priv, + "%s: timeout:%x CR: %x!\n", __func__, err, reg); + return -EINVAL; + } + } else { + reg = priv->pm_conf.cr; + reg |= RNG_CR_RNGEN; + writel_relaxed(reg, priv->base + RNG_CR); + } + + return 0; +} + +static const struct dev_pm_ops __maybe_unused stm32_rng_pm_ops = { + SET_RUNTIME_PM_OPS(stm32_rng_runtime_suspend, + stm32_rng_runtime_resume, NULL) + SET_SYSTEM_SLEEP_PM_OPS(stm32_rng_suspend, + stm32_rng_resume) +}; + +static const struct stm32_rng_data stm32mp13_rng_data = { + .has_cond_reset = true, + .max_clock_rate = 48000000, + .cr = 0x00F00D00, + .nscr = 0x2B5BB, + .htcr = 0x969D, +}; + +static const struct stm32_rng_data stm32_rng_data = { + .has_cond_reset = false, + .max_clock_rate = 3000000, +}; + +static const struct of_device_id stm32_rng_match[] = { + { + .compatible = "st,stm32mp13-rng", + .data = &stm32mp13_rng_data, + }, + { + .compatible = "st,stm32-rng", + .data = &stm32_rng_data, + }, + {}, +}; +MODULE_DEVICE_TABLE(of, stm32_rng_match); + static int stm32_rng_probe(struct platform_device *ofdev) { struct device *dev = &ofdev->dev; struct device_node *np = ofdev->dev.of_node; struct stm32_rng_private *priv; - struct resource res; - int err; + struct resource *res; priv = devm_kzalloc(dev, sizeof(struct stm32_rng_private), GFP_KERNEL); if (!priv) return -ENOMEM; - err = of_address_to_resource(np, 0, &res); - if (err) - return err; - - priv->base = devm_ioremap_resource(dev, &res); + priv->base = devm_platform_get_and_ioremap_resource(ofdev, 0, &res); if (IS_ERR(priv->base)) return PTR_ERR(priv->base); @@ -145,14 +530,16 @@ static int stm32_rng_probe(struct platform_device *ofdev) } priv->ced = of_property_read_bool(np, "clock-error-detect"); + priv->lock_conf = of_property_read_bool(np, "st,rng-lock-conf"); + + priv->data = of_device_get_match_data(dev); + if (!priv->data) + return -ENODEV; dev_set_drvdata(dev, priv); priv->rng.name = dev_driver_string(dev); -#ifndef CONFIG_PM priv->rng.init = stm32_rng_init; - priv->rng.cleanup = stm32_rng_cleanup; -#endif priv->rng.read = stm32_rng_read; priv->rng.priv = (unsigned long) dev; priv->rng.quality = 900; @@ -164,51 +551,10 @@ static int stm32_rng_probe(struct platform_device *ofdev) return devm_hwrng_register(dev, &priv->rng); } -static int stm32_rng_remove(struct platform_device *ofdev) -{ - pm_runtime_disable(&ofdev->dev); - - return 0; -} - -#ifdef CONFIG_PM -static int stm32_rng_runtime_suspend(struct device *dev) -{ - struct stm32_rng_private *priv = dev_get_drvdata(dev); - - stm32_rng_cleanup(&priv->rng); - - return 0; -} - -static int stm32_rng_runtime_resume(struct device *dev) -{ - struct stm32_rng_private *priv = dev_get_drvdata(dev); - - return stm32_rng_init(&priv->rng); -} -#endif - -static const struct dev_pm_ops stm32_rng_pm_ops = { - SET_RUNTIME_PM_OPS(stm32_rng_runtime_suspend, - stm32_rng_runtime_resume, NULL) - SET_SYSTEM_SLEEP_PM_OPS(pm_runtime_force_suspend, - pm_runtime_force_resume) -}; - - -static const struct of_device_id stm32_rng_match[] = { - { - .compatible = "st,stm32-rng", - }, - {}, -}; -MODULE_DEVICE_TABLE(of, stm32_rng_match); - static struct platform_driver stm32_rng_driver = { .driver = { .name = "stm32-rng", - .pm = &stm32_rng_pm_ops, + .pm = pm_ptr(&stm32_rng_pm_ops), .of_match_table = stm32_rng_match, }, .probe = stm32_rng_probe, |