From: Sunil Goutham <sgoutham@xxxxxxxxxxx>
CN10K series of silicons support true random number
generators. This patch adds support for the same. Also
supports entropy health status checking.
Signed-off-by: Sunil Goutham <sgoutham@xxxxxxxxxxx>
Signed-off-by: Bharat Bhushan <bbhushan2@xxxxxxxxxxx>
Signed-off-by: Joseph Longever <jlongever@xxxxxxxxxxx>
---
drivers/char/hw_random/Kconfig | 11 ++
drivers/char/hw_random/Makefile | 1 +
drivers/char/hw_random/cn10k-rng.c | 205 +++++++++++++++++++++++++++++++++++++
3 files changed, 217 insertions(+)
create mode 100644 drivers/char/hw_random/cn10k-rng.c
diff --git a/drivers/char/hw_random/Kconfig b/drivers/char/hw_random/Kconfig
index 1da6477..001b819 100644
--- a/drivers/char/hw_random/Kconfig
+++ b/drivers/char/hw_random/Kconfig
@@ -538,6 +538,17 @@ config HW_RANDOM_ARM_SMCCC_TRNG
To compile this driver as a module, choose M here: the
module will be called arm_smccc_trng.
+config HW_RANDOM_CN10K
+ tristate "Marvell CN10K Random Number Generator support"
+ depends on HW_RANDOM && PCI && ARM64
+ default HW_RANDOM
+ help
+ This driver provides support for the True Random Number
+ generator available in Marvell CN10K SoCs.
+
+ To compile this driver as a module, choose M here.
+ The module will be called cn10k_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 a5a1c76..a2f1ce0 100644
--- a/drivers/char/hw_random/Makefile
+++ b/drivers/char/hw_random/Makefile
@@ -46,3 +46,4 @@ obj-$(CONFIG_HW_RANDOM_NPCM) += npcm-rng.o
obj-$(CONFIG_HW_RANDOM_CCTRNG) += cctrng.o
obj-$(CONFIG_HW_RANDOM_XIPHERA) += xiphera-trng.o
obj-$(CONFIG_HW_RANDOM_ARM_SMCCC_TRNG) += arm_smccc_trng.o
+obj-$(CONFIG_HW_RANDOM_CN10K) += cn10k-rng.o
diff --git a/drivers/char/hw_random/cn10k-rng.c b/drivers/char/hw_random/cn10k-rng.c
new file mode 100644
index 0000000..e348732
--- /dev/null
+++ b/drivers/char/hw_random/cn10k-rng.c
@@ -0,0 +1,205 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Marvell CN10K RVU Hardware Random Number Generator.
+ *
+ * Copyright (C) 2021 Marvell.
+ *
+ */
+
+#include <linux/hw_random.h>
+#include <linux/io.h>
+#include <linux/module.h>
+#include <linux/pci.h>
+#include <linux/pci_ids.h>
+#include <linux/delay.h>
+
+#include <linux/arm-smccc.h>
+
+/* CSRs */
+#define RNM_CTL_STATUS 0x000
+#define RNM_ENTROPY_STATUS 0x008
+#define RNM_CONST 0x030
+#define RNM_EBG_ENT 0x048
+#define RNM_PF_EBG_HEALTH 0x050
+#define RNM_PF_RANDOM 0x400
+#define RNM_TRNG_RESULT 0x408
+
+struct cn10k_rng {
+ void __iomem *reg_base;
+ struct hwrng ops;
+ struct pci_dev *pdev;
+};
+
+#define PLAT_OCTEONTX_RESET_RNG_EBG_HEALTH_STATE 0xc2000b0f
+
+static int reset_rng_health_state(struct cn10k_rng *rng)
+{
+ struct arm_smccc_res res;
+ int ret = 0;
+
+ /* Send SMC service call to reset EBG health state */
+ arm_smccc_smc(PLAT_OCTEONTX_RESET_RNG_EBG_HEALTH_STATE, 0, 0, 0, 0, 0, 0, 0, &res);
+ if (res.a0 == 0UL) {
+ dev_info(&rng->pdev->dev, "HWRNG: reset completed\n");
+ } else {
+ dev_err(&rng->pdev->dev, "HWRNG: error during reset\n");
+ ret = -EIO;
+ }
+
+ return ret;
+}
+
+static int check_rng_health(struct cn10k_rng *rng)
+{
+ u64 status;
+
+ /* Skip checking health */
+ if (!rng->reg_base)
+ return 0;
+
+ status = readq(rng->reg_base + RNM_PF_EBG_HEALTH);
+ if (status & BIT_ULL(20)) {
+ dev_err(&rng->pdev->dev,
+ "HWRNG: Health test failed (status=%llx)\n", status);
+ return reset_rng_health_state(rng);
+ }
+ return 0;
+}
+
+static int cn10k_check_entropy(struct cn10k_rng *rng)
+{
+ int retries = 5;
+ u64 ent_status;
+
+ while (retries) {
+ ent_status = readq(rng->reg_base + RNM_ENTROPY_STATUS);
+ if (ent_status & 0x7FULL)
+ break;
+ udelay(20);
+ retries--;
+ }
+ return ent_status & 0x7FULL;
+}
+
+static int cn10k_read_trng(struct cn10k_rng *rng, u64 *value)
+{
+ u64 addr, result = 0;
+ int retry_count = 5;
+
+ addr = (u64)rng->reg_base + RNM_PF_RANDOM;
+ /* TRNG and status need to be read at a time */
+ while (!result && retry_count) {
+ __asm__ volatile("ldp %0,%1,[%2]" :\
+ "=r" (*value), "=r" (result) : "r" (addr) : );
+
+ retry_count--;
+ }
+
+ return retry_count ? 0 : -EIO;
+}
+
+static int cn10k_rng_read(struct hwrng *hwrng, void *data,
+ size_t max, bool wait)
+{
+ struct cn10k_rng *rng = (struct cn10k_rng *)hwrng->priv;
+ unsigned int size;
+ int err = 0;
+ u64 value;
+
+ err = check_rng_health(rng);
+ if (err)
+ return err;
+
+ /* HW can run out of entropy if large amount random data is read in
+ * quick succession. So check if it's available to be read.
+ */
+ size = cn10k_check_entropy(rng);
+ if (size > max)
+ size = max;
+ else
+ max = size;
+
+ while (size >= 8) {
+ err = cn10k_read_trng(rng, &value);
+ if (err)
+ goto exit;
+
+ *((u64 *)data) = (u64)value;
+ size -= 8;
+ data += 8;
+ }
+
+ while (size > 0) {
+ err = cn10k_read_trng(rng, &value);
+ if (err)
+ goto exit;
+
+ *((u8 *)data) = (u8)value;
+ size--;
+ data++;
+ }
+
+exit:
+ return max - size;
+}
+
+static int cn10k_rng_probe(struct pci_dev *pdev, const struct pci_device_id *id)
+{
+ struct cn10k_rng *rng;
+ int err;
+
+ rng = devm_kzalloc(&pdev->dev, sizeof(*rng), GFP_KERNEL);
+ if (!rng)
+ return -ENOMEM;
+
+ rng->pdev = pdev;
+ pci_set_drvdata(pdev, rng);
+
+ rng->reg_base = pcim_iomap(pdev, 0, 0);
+ if (!rng->reg_base) {
+ dev_err(&pdev->dev, "Error while mapping CSRs, exiting\n");
+ return -ENOMEM;
+ }
+
+ rng->ops.name = devm_kasprintf(&pdev->dev, GFP_KERNEL,
+ "cn10k-rng-%s", dev_name(&pdev->dev));
+ if (!rng->ops.name)
+ return -ENOMEM;
+
+ rng->ops.read = cn10k_rng_read;
+ rng->ops.quality = 1000;
+ rng->ops.priv = (unsigned long)rng;
+
+ err = devm_hwrng_register(&pdev->dev, &rng->ops);
+ if (err) {
+ dev_err(&pdev->dev, "Could not register hwrng device.\n");
+ return err;
+ }
+
+ reset_rng_health_state(rng);
+
+ return 0;
+}
+
+static void cn10k_rng_remove(struct pci_dev *pdev)
+{
+ /* Nothing to do */
+}
+
+static const struct pci_device_id cn10k_rng_id_table[] = {
+ { PCI_DEVICE(PCI_VENDOR_ID_CAVIUM, 0xA098) }, /* RNG PF */
+ {0,},
+};
+
+MODULE_DEVICE_TABLE(pci, cn10k_rng_id_table);
+
+static struct pci_driver cn10k_rng_driver = {
+ .name = "cn10k_rng",
+ .id_table = cn10k_rng_id_table,
+ .probe = cn10k_rng_probe,
+ .remove = cn10k_rng_remove,
+};
+
+module_pci_driver(cn10k_rng_driver);
+MODULE_AUTHOR("Sunil Goutham <sgoutham@xxxxxxxxxxx>");
+MODULE_DESCRIPTION("Marvell CN10K HW RNG Driver");
+MODULE_LICENSE("GPL v2");
--
2.7.4
