1 files changed, 428 insertions, 83 deletions

diff --git a/drivers/char/hw_random/stm32-rng.c b/drivers/char/hw_random/stm32-rng.c
index efb6a9f9a11b..41e1dbea5d2e 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 +256,264 @@ 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) {
+			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 +529,16 @@ 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 +550,10 @@ 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,