hwrng: xgene - add support for APM X-Gene SoC RNG support

This adds the APM X-Gene SoC RNG support.

Signed-off-by: Feng Kan <fkan@apm.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

3 files changed, 437 insertions, 0 deletions

diff --git a/drivers/char/hw_random/Kconfig b/drivers/char/hw_random/Kconfig
index 836b061ced35..91a04ae8003c 100644
--- a/drivers/char/hw_random/Kconfig
+++ b/drivers/char/hw_random/Kconfig
@@ -333,6 +333,19 @@ config HW_RANDOM_MSM
 
 	  If unsure, say Y.
 
+config HW_RANDOM_XGENE
+	tristate "APM X-Gene True Random Number Generator (TRNG) support"
+	depends on HW_RANDOM && ARCH_XGENE
+	default HW_RANDOM
+	---help---
+	  This driver provides kernel-side support for the Random Number
+	  Generator hardware found on APM X-Gene SoC.
+
+	  To compile this driver as a module, choose M here: the
+	  module will be called xgene_rng.
+
+	  If unsure, say Y.
+
 endif # HW_RANDOM
 
 config UML_RANDOM
diff --git a/drivers/char/hw_random/Makefile b/drivers/char/hw_random/Makefile
index 199ed283e149..0b4cd57f4e24 100644
--- a/drivers/char/hw_random/Makefile
+++ b/drivers/char/hw_random/Makefile
@@ -29,3 +29,4 @@ obj-$(CONFIG_HW_RANDOM_EXYNOS)	+= exynos-rng.o
 obj-$(CONFIG_HW_RANDOM_TPM) += tpm-rng.o
 obj-$(CONFIG_HW_RANDOM_BCM2835) += bcm2835-rng.o
 obj-$(CONFIG_HW_RANDOM_MSM) += msm-rng.o
+obj-$(CONFIG_HW_RANDOM_XGENE) += xgene-rng.o
diff --git a/drivers/char/hw_random/xgene-rng.c b/drivers/char/hw_random/xgene-rng.c
new file mode 100644
index 000000000000..23caa05380a8
--- /dev/null
+++ b/drivers/char/hw_random/xgene-rng.c
@@ -0,0 +1,423 @@
+/*
+ * APM X-Gene SoC RNG Driver
+ *
+ * Copyright (c) 2014, Applied Micro Circuits Corporation
+ * Author: Rameshwar Prasad Sahu <rsahu@apm.com>
+ *	   Shamal Winchurkar <swinchurkar@apm.com>
+ *	   Feng Kan <fkan@apm.com>
+ *
+ * This program is free software; you can redistribute  it and/or modify it
+ * under  the terms of  the GNU General  Public License as published by the
+ * Free Software Foundation;  either version 2 of the  License, or (at your
+ * option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+#include <linux/clk.h>
+#include <linux/delay.h>
+#include <linux/hw_random.h>
+#include <linux/init.h>
+#include <linux/interrupt.h>
+#include <linux/module.h>
+#include <linux/of_platform.h>
+#include <linux/of_irq.h>
+#include <linux/of_address.h>
+#include <linux/timer.h>
+
+#define RNG_MAX_DATUM			4
+#define MAX_TRY				100
+#define XGENE_RNG_RETRY_COUNT		20
+#define XGENE_RNG_RETRY_INTERVAL	10
+
+/* RNG  Registers */
+#define RNG_INOUT_0			0x00
+#define RNG_INTR_STS_ACK		0x10
+#define RNG_CONTROL			0x14
+#define RNG_CONFIG			0x18
+#define RNG_ALARMCNT			0x1c
+#define RNG_FROENABLE			0x20
+#define RNG_FRODETUNE			0x24
+#define RNG_ALARMMASK			0x28
+#define RNG_ALARMSTOP			0x2c
+#define RNG_OPTIONS			0x78
+#define RNG_EIP_REV			0x7c
+
+#define MONOBIT_FAIL_MASK		BIT(7)
+#define POKER_FAIL_MASK			BIT(6)
+#define LONG_RUN_FAIL_MASK		BIT(5)
+#define RUN_FAIL_MASK			BIT(4)
+#define NOISE_FAIL_MASK			BIT(3)
+#define STUCK_OUT_MASK			BIT(2)
+#define SHUTDOWN_OFLO_MASK		BIT(1)
+#define READY_MASK			BIT(0)
+
+#define MAJOR_HW_REV_RD(src)		(((src) & 0x0f000000) >> 24)
+#define MINOR_HW_REV_RD(src)		(((src) & 0x00f00000) >> 20)
+#define HW_PATCH_LEVEL_RD(src)		(((src) & 0x000f0000) >> 16)
+#define MAX_REFILL_CYCLES_SET(dst, src) \
+			((dst & ~0xffff0000) | (((u32)src << 16) & 0xffff0000))
+#define MIN_REFILL_CYCLES_SET(dst, src) \
+			((dst & ~0x000000ff) | (((u32)src) & 0x000000ff))
+#define ALARM_THRESHOLD_SET(dst, src) \
+			((dst & ~0x000000ff) | (((u32)src) & 0x000000ff))
+#define ENABLE_RNG_SET(dst, src) \
+			((dst & ~BIT(10)) | (((u32)src << 10) & BIT(10)))
+#define REGSPEC_TEST_MODE_SET(dst, src) \
+			((dst & ~BIT(8)) | (((u32)src << 8) & BIT(8)))
+#define MONOBIT_FAIL_MASK_SET(dst, src) \
+			((dst & ~BIT(7)) | (((u32)src << 7) & BIT(7)))
+#define POKER_FAIL_MASK_SET(dst, src) \
+			((dst & ~BIT(6)) | (((u32)src << 6) & BIT(6)))
+#define LONG_RUN_FAIL_MASK_SET(dst, src) \
+			((dst & ~BIT(5)) | (((u32)src << 5) & BIT(5)))
+#define RUN_FAIL_MASK_SET(dst, src) \
+			((dst & ~BIT(4)) | (((u32)src << 4) & BIT(4)))
+#define NOISE_FAIL_MASK_SET(dst, src) \
+			((dst & ~BIT(3)) | (((u32)src << 3) & BIT(3)))
+#define STUCK_OUT_MASK_SET(dst, src) \
+			((dst & ~BIT(2)) | (((u32)src << 2) & BIT(2)))
+#define SHUTDOWN_OFLO_MASK_SET(dst, src) \
+			((dst & ~BIT(1)) | (((u32)src << 1) & BIT(1)))
+
+struct xgene_rng_dev {
+	u32 irq;
+	void  __iomem *csr_base;
+	u32 revision;
+	u32 datum_size;
+	u32 failure_cnt;	/* Failure count last minute */
+	unsigned long failure_ts;/* First failure timestamp */
+	struct timer_list failure_timer;
+	struct device *dev;
+	struct clk *clk;
+};
+
+static void xgene_rng_expired_timer(unsigned long arg)
+{
+	struct xgene_rng_dev *ctx = (struct xgene_rng_dev *) arg;
+
+	/* Clear failure counter as timer expired */
+	disable_irq(ctx->irq);
+	ctx->failure_cnt = 0;
+	del_timer(&ctx->failure_timer);
+	enable_irq(ctx->irq);
+}
+
+static void xgene_rng_start_timer(struct xgene_rng_dev *ctx)
+{
+	ctx->failure_timer.data = (unsigned long) ctx;
+	ctx->failure_timer.function = xgene_rng_expired_timer;
+	ctx->failure_timer.expires = jiffies + 120 * HZ;
+	add_timer(&ctx->failure_timer);
+}
+
+/*
+ * Initialize or reinit free running oscillators (FROs)
+ */
+static void xgene_rng_init_fro(struct xgene_rng_dev *ctx, u32 fro_val)
+{
+	writel(fro_val, ctx->csr_base + RNG_FRODETUNE);
+	writel(0x00000000, ctx->csr_base + RNG_ALARMMASK);
+	writel(0x00000000, ctx->csr_base + RNG_ALARMSTOP);
+	writel(0xFFFFFFFF, ctx->csr_base + RNG_FROENABLE);
+}
+
+static void xgene_rng_chk_overflow(struct xgene_rng_dev *ctx)
+{
+	u32 val;
+
+	val = readl(ctx->csr_base + RNG_INTR_STS_ACK);
+	if (val & MONOBIT_FAIL_MASK)
+		/*
+		 * LFSR detected an out-of-bounds number of 1s after
+		 * checking 20,000 bits (test T1 as specified in the
+		 * AIS-31 standard)
+		 */
+		dev_err(ctx->dev, "test monobit failure error 0x%08X\n", val);
+	if (val & POKER_FAIL_MASK)
+		/*
+		 * LFSR detected an out-of-bounds value in at least one
+		 * of the 16 poker_count_X counters or an out of bounds sum
+		 * of squares value after checking 20,000 bits (test T2 as
+		 * specified in the AIS-31 standard)
+		 */
+		dev_err(ctx->dev, "test poker failure error 0x%08X\n", val);
+	if (val & LONG_RUN_FAIL_MASK)
+		/*
+		 * LFSR detected a sequence of 34 identical bits
+		 * (test T4 as specified in the AIS-31 standard)
+		 */
+		dev_err(ctx->dev, "test long run failure error 0x%08X\n", val);
+	if (val & RUN_FAIL_MASK)
+		/*
+		 * LFSR detected an outof-bounds value for at least one
+		 * of the running counters after checking 20,000 bits
+		 * (test T3 as specified in the AIS-31 standard)
+		 */
+		dev_err(ctx->dev, "test run failure error 0x%08X\n", val);
+	if (val & NOISE_FAIL_MASK)
+		/* LFSR detected a sequence of 48 identical bits */
+		dev_err(ctx->dev, "noise failure error 0x%08X\n", val);
+	if (val & STUCK_OUT_MASK)
+		/*
+		 * Detected output data registers generated same value twice
+		 * in a row
+		 */
+		dev_err(ctx->dev, "stuck out failure error 0x%08X\n", val);
+
+	if (val & SHUTDOWN_OFLO_MASK) {
+		u32 frostopped;
+
+		/* FROs shut down after a second error event. Try recover. */
+		if (++ctx->failure_cnt == 1) {
+			/* 1st time, just recover */
+			ctx->failure_ts = jiffies;
+			frostopped = readl(ctx->csr_base + RNG_ALARMSTOP);
+			xgene_rng_init_fro(ctx, frostopped);
+
+			/*
+			 * We must start a timer to clear out this error
+			 * in case the system timer wrap around
+			 */
+			xgene_rng_start_timer(ctx);
+		} else {
+			/* 2nd time failure in lesser than 1 minute? */
+			if (time_after(ctx->failure_ts + 60 * HZ, jiffies)) {
+				dev_err(ctx->dev,
+					"FRO shutdown failure error 0x%08X\n",
+					val);
+			} else {
+				/* 2nd time failure after 1 minutes, recover */
+				ctx->failure_ts = jiffies;
+				ctx->failure_cnt = 1;
+				/*
+				 * We must start a timer to clear out this
+				 * error in case the system timer wrap
+				 * around
+				 */
+				xgene_rng_start_timer(ctx);
+			}
+			frostopped = readl(ctx->csr_base + RNG_ALARMSTOP);
+			xgene_rng_init_fro(ctx, frostopped);
+		}
+	}
+	/* Clear them all */
+	writel(val, ctx->csr_base + RNG_INTR_STS_ACK);
+}
+
+static irqreturn_t xgene_rng_irq_handler(int irq, void *id)
+{
+	struct xgene_rng_dev *ctx = (struct xgene_rng_dev *) id;
+
+	/* RNG Alarm Counter overflow */
+	xgene_rng_chk_overflow(ctx);
+
+	return IRQ_HANDLED;
+}
+
+static int xgene_rng_data_present(struct hwrng *rng, int wait)
+{
+	struct xgene_rng_dev *ctx = (struct xgene_rng_dev *) rng->priv;
+	u32 i, val = 0;
+
+	for (i = 0; i < XGENE_RNG_RETRY_COUNT; i++) {
+		val = readl(ctx->csr_base + RNG_INTR_STS_ACK);
+		if ((val & READY_MASK) || !wait)
+			break;
+		udelay(XGENE_RNG_RETRY_INTERVAL);
+	}
+
+	return (val & READY_MASK);
+}
+
+static int xgene_rng_data_read(struct hwrng *rng, u32 *data)
+{
+	struct xgene_rng_dev *ctx = (struct xgene_rng_dev *) rng->priv;
+	int i;
+
+	for (i = 0; i < ctx->datum_size; i++)
+		data[i] = readl(ctx->csr_base + RNG_INOUT_0 + i * 4);
+
+	/* Clear ready bit to start next transaction */
+	writel(READY_MASK, ctx->csr_base + RNG_INTR_STS_ACK);
+
+	return ctx->datum_size << 2;
+}
+
+static void xgene_rng_init_internal(struct xgene_rng_dev *ctx)
+{
+	u32 val;
+
+	writel(0x00000000, ctx->csr_base + RNG_CONTROL);
+
+	val = MAX_REFILL_CYCLES_SET(0, 10);
+	val = MIN_REFILL_CYCLES_SET(val, 10);
+	writel(val, ctx->csr_base + RNG_CONFIG);
+
+	val = ALARM_THRESHOLD_SET(0, 0xFF);
+	writel(val, ctx->csr_base + RNG_ALARMCNT);
+
+	xgene_rng_init_fro(ctx, 0);
+
+	writel(MONOBIT_FAIL_MASK |
+		POKER_FAIL_MASK	|
+		LONG_RUN_FAIL_MASK |
+		RUN_FAIL_MASK |
+		NOISE_FAIL_MASK |
+		STUCK_OUT_MASK |
+		SHUTDOWN_OFLO_MASK |
+		READY_MASK, ctx->csr_base + RNG_INTR_STS_ACK);
+
+	val = ENABLE_RNG_SET(0, 1);
+	val = MONOBIT_FAIL_MASK_SET(val, 1);
+	val = POKER_FAIL_MASK_SET(val, 1);
+	val = LONG_RUN_FAIL_MASK_SET(val, 1);
+	val = RUN_FAIL_MASK_SET(val, 1);
+	val = NOISE_FAIL_MASK_SET(val, 1);
+	val = STUCK_OUT_MASK_SET(val, 1);
+	val = SHUTDOWN_OFLO_MASK_SET(val, 1);
+	writel(val, ctx->csr_base + RNG_CONTROL);
+}
+
+static int xgene_rng_init(struct hwrng *rng)
+{
+	struct xgene_rng_dev *ctx = (struct xgene_rng_dev *) rng->priv;
+
+	ctx->failure_cnt = 0;
+	init_timer(&ctx->failure_timer);
+
+	ctx->revision = readl(ctx->csr_base + RNG_EIP_REV);
+
+	dev_dbg(ctx->dev, "Rev %d.%d.%d\n",
+		MAJOR_HW_REV_RD(ctx->revision),
+		MINOR_HW_REV_RD(ctx->revision),
+		HW_PATCH_LEVEL_RD(ctx->revision));
+
+	dev_dbg(ctx->dev, "Options 0x%08X",
+		readl(ctx->csr_base + RNG_OPTIONS));
+
+	xgene_rng_init_internal(ctx);
+
+	ctx->datum_size = RNG_MAX_DATUM;
+
+	return 0;
+}
+
+static struct hwrng xgene_rng_func = {
+	.name		= "xgene-rng",
+	.init		= xgene_rng_init,
+	.data_present	= xgene_rng_data_present,
+	.data_read	= xgene_rng_data_read,
+};
+
+static int xgene_rng_probe(struct platform_device *pdev)
+{
+	struct resource *res;
+	struct xgene_rng_dev *ctx;
+	int rc = 0;
+
+	ctx = devm_kzalloc(&pdev->dev, sizeof(*ctx), GFP_KERNEL);
+	if (!ctx)
+		return -ENOMEM;
+
+	ctx->dev = &pdev->dev;
+	platform_set_drvdata(pdev, ctx);
+
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	ctx->csr_base = devm_ioremap_resource(&pdev->dev, res);
+	if (IS_ERR(ctx->csr_base))
+		return PTR_ERR(ctx->csr_base);
+
+	ctx->irq = platform_get_irq(pdev, 0);
+	if (ctx->irq < 0) {
+		dev_err(&pdev->dev, "No IRQ resource\n");
+		return ctx->irq;
+	}
+
+	dev_dbg(&pdev->dev, "APM X-Gene RNG BASE %p ALARM IRQ %d",
+		ctx->csr_base, ctx->irq);
+
+	rc = devm_request_irq(&pdev->dev, ctx->irq, xgene_rng_irq_handler, 0,
+				dev_name(&pdev->dev), ctx);
+	if (rc) {
+		dev_err(&pdev->dev, "Could not request RNG alarm IRQ\n");
+		return rc;
+	}
+
+	/* Enable IP clock */
+	ctx->clk = devm_clk_get(&pdev->dev, NULL);
+	if (IS_ERR(ctx->clk)) {
+		dev_warn(&pdev->dev, "Couldn't get the clock for RNG\n");
+	} else {
+		rc = clk_prepare_enable(ctx->clk);
+		if (rc) {
+			dev_warn(&pdev->dev,
+				 "clock prepare enable failed for RNG");
+			return rc;
+		}
+	}
+
+	xgene_rng_func.priv = (unsigned long) ctx;
+
+	rc = hwrng_register(&xgene_rng_func);
+	if (rc) {
+		dev_err(&pdev->dev, "RNG registering failed error %d\n", rc);
+		if (!IS_ERR(ctx->clk))
+			clk_disable_unprepare(ctx->clk);
+		return rc;
+	}
+
+	rc = device_init_wakeup(&pdev->dev, 1);
+	if (rc) {
+		dev_err(&pdev->dev, "RNG device_init_wakeup failed error %d\n",
+			rc);
+		if (!IS_ERR(ctx->clk))
+			clk_disable_unprepare(ctx->clk);
+		hwrng_unregister(&xgene_rng_func);
+		return rc;
+	}
+
+	return 0;
+}
+
+static int xgene_rng_remove(struct platform_device *pdev)
+{
+	struct xgene_rng_dev *ctx = platform_get_drvdata(pdev);
+	int rc;
+
+	rc = device_init_wakeup(&pdev->dev, 0);
+	if (rc)
+		dev_err(&pdev->dev, "RNG init wakeup failed error %d\n", rc);
+	if (!IS_ERR(ctx->clk))
+		clk_disable_unprepare(ctx->clk);
+	hwrng_unregister(&xgene_rng_func);
+
+	return rc;
+}
+
+static const struct of_device_id xgene_rng_of_match[] = {
+	{ .compatible = "apm,xgene-rng" },
+	{ }
+};
+
+MODULE_DEVICE_TABLE(of, xgene_rng_of_match);
+
+static struct platform_driver xgene_rng_driver = {
+	.probe = xgene_rng_probe,
+	.remove	= xgene_rng_remove,
+	.driver = {
+		.name		= "xgene-rng",
+		.of_match_table = xgene_rng_of_match,
+	},
+};
+
+module_platform_driver(xgene_rng_driver);
+MODULE_DESCRIPTION("APM X-Gene RNG driver");
+MODULE_LICENSE("GPL");