diff options
Diffstat (limited to 'drivers/char/hw_random/airoha-trng.c')
| -rw-r--r-- | drivers/char/hw_random/airoha-trng.c | 243 |
1 files changed, 243 insertions, 0 deletions
diff --git a/drivers/char/hw_random/airoha-trng.c b/drivers/char/hw_random/airoha-trng.c new file mode 100644 index 000000000000..1dbfa9505c21 --- /dev/null +++ b/drivers/char/hw_random/airoha-trng.c @@ -0,0 +1,243 @@ +// SPDX-License-Identifier: GPL-2.0 +/* Copyright (C) 2024 Christian Marangi */ + +#include <linux/kernel.h> +#include <linux/module.h> +#include <linux/mod_devicetable.h> +#include <linux/bitfield.h> +#include <linux/delay.h> +#include <linux/hw_random.h> +#include <linux/interrupt.h> +#include <linux/io.h> +#include <linux/iopoll.h> +#include <linux/platform_device.h> + +#define TRNG_IP_RDY 0x800 +#define CNT_TRANS GENMASK(15, 8) +#define SAMPLE_RDY BIT(0) +#define TRNG_NS_SEK_AND_DAT_EN 0x804 +#define RNG_EN BIT(31) /* referenced as ring_en */ +#define RAW_DATA_EN BIT(16) +#define TRNG_HEALTH_TEST_SW_RST 0x808 +#define SW_RST BIT(0) /* Active High */ +#define TRNG_INTR_EN 0x818 +#define INTR_MASK BIT(16) +#define CONTINUOUS_HEALTH_INITR_EN BIT(2) +#define SW_STARTUP_INITR_EN BIT(1) +#define RST_STARTUP_INITR_EN BIT(0) +/* Notice that Health Test are done only out of Reset and with RNG_EN */ +#define TRNG_HEALTH_TEST_STATUS 0x824 +#define CONTINUOUS_HEALTH_AP_TEST_FAIL BIT(23) +#define CONTINUOUS_HEALTH_RC_TEST_FAIL BIT(22) +#define SW_STARTUP_TEST_DONE BIT(21) +#define SW_STARTUP_AP_TEST_FAIL BIT(20) +#define SW_STARTUP_RC_TEST_FAIL BIT(19) +#define RST_STARTUP_TEST_DONE BIT(18) +#define RST_STARTUP_AP_TEST_FAIL BIT(17) +#define RST_STARTUP_RC_TEST_FAIL BIT(16) +#define RAW_DATA_VALID BIT(7) + +#define TRNG_RAW_DATA_OUT 0x828 + +#define TRNG_CNT_TRANS_VALID 0x80 +#define BUSY_LOOP_SLEEP 10 +#define BUSY_LOOP_TIMEOUT (BUSY_LOOP_SLEEP * 10000) + +struct airoha_trng { + void __iomem *base; + struct hwrng rng; + struct device *dev; + + struct completion rng_op_done; +}; + +static int airoha_trng_irq_mask(struct airoha_trng *trng) +{ + u32 val; + + val = readl(trng->base + TRNG_INTR_EN); + val |= INTR_MASK; + writel(val, trng->base + TRNG_INTR_EN); + + return 0; +} + +static int airoha_trng_irq_unmask(struct airoha_trng *trng) +{ + u32 val; + + val = readl(trng->base + TRNG_INTR_EN); + val &= ~INTR_MASK; + writel(val, trng->base + TRNG_INTR_EN); + + return 0; +} + +static int airoha_trng_init(struct hwrng *rng) +{ + struct airoha_trng *trng = container_of(rng, struct airoha_trng, rng); + int ret; + u32 val; + + val = readl(trng->base + TRNG_NS_SEK_AND_DAT_EN); + val |= RNG_EN; + writel(val, trng->base + TRNG_NS_SEK_AND_DAT_EN); + + /* Set out of SW Reset */ + airoha_trng_irq_unmask(trng); + writel(0, trng->base + TRNG_HEALTH_TEST_SW_RST); + + ret = wait_for_completion_timeout(&trng->rng_op_done, BUSY_LOOP_TIMEOUT); + if (ret <= 0) { + dev_err(trng->dev, "Timeout waiting for Health Check\n"); + airoha_trng_irq_mask(trng); + return -ENODEV; + } + + /* Check if Health Test Failed */ + val = readl(trng->base + TRNG_HEALTH_TEST_STATUS); + if (val & (RST_STARTUP_AP_TEST_FAIL | RST_STARTUP_RC_TEST_FAIL)) { + dev_err(trng->dev, "Health Check fail: %s test fail\n", + val & RST_STARTUP_AP_TEST_FAIL ? "AP" : "RC"); + return -ENODEV; + } + + /* Check if IP is ready */ + ret = readl_poll_timeout(trng->base + TRNG_IP_RDY, val, + val & SAMPLE_RDY, 10, 1000); + if (ret < 0) { + dev_err(trng->dev, "Timeout waiting for IP ready"); + return -ENODEV; + } + + /* CNT_TRANS must be 0x80 for IP to be considered ready */ + ret = readl_poll_timeout(trng->base + TRNG_IP_RDY, val, + FIELD_GET(CNT_TRANS, val) == TRNG_CNT_TRANS_VALID, + 10, 1000); + if (ret < 0) { + dev_err(trng->dev, "Timeout waiting for IP ready"); + return -ENODEV; + } + + return 0; +} + +static void airoha_trng_cleanup(struct hwrng *rng) +{ + struct airoha_trng *trng = container_of(rng, struct airoha_trng, rng); + u32 val; + + val = readl(trng->base + TRNG_NS_SEK_AND_DAT_EN); + val &= ~RNG_EN; + writel(val, trng->base + TRNG_NS_SEK_AND_DAT_EN); + + /* Put it in SW Reset */ + writel(SW_RST, trng->base + TRNG_HEALTH_TEST_SW_RST); +} + +static int airoha_trng_read(struct hwrng *rng, void *buf, size_t max, bool wait) +{ + struct airoha_trng *trng = container_of(rng, struct airoha_trng, rng); + u32 *data = buf; + u32 status; + int ret; + + ret = readl_poll_timeout(trng->base + TRNG_HEALTH_TEST_STATUS, status, + status & RAW_DATA_VALID, 10, 1000); + if (ret < 0) { + dev_err(trng->dev, "Timeout waiting for TRNG RAW Data valid\n"); + return ret; + } + + *data = readl(trng->base + TRNG_RAW_DATA_OUT); + + return 4; +} + +static irqreturn_t airoha_trng_irq(int irq, void *priv) +{ + struct airoha_trng *trng = (struct airoha_trng *)priv; + + airoha_trng_irq_mask(trng); + /* Just complete the task, we will read the value later */ + complete(&trng->rng_op_done); + + return IRQ_HANDLED; +} + +static int airoha_trng_probe(struct platform_device *pdev) +{ + struct device *dev = &pdev->dev; + struct airoha_trng *trng; + int irq, ret; + u32 val; + + trng = devm_kzalloc(dev, sizeof(*trng), GFP_KERNEL); + if (!trng) + return -ENOMEM; + + trng->base = devm_platform_ioremap_resource(pdev, 0); + if (IS_ERR(trng->base)) + return PTR_ERR(trng->base); + + irq = platform_get_irq(pdev, 0); + if (irq < 0) + return irq; + + airoha_trng_irq_mask(trng); + ret = devm_request_irq(&pdev->dev, irq, airoha_trng_irq, 0, + pdev->name, (void *)trng); + if (ret) { + dev_err(dev, "Can't get interrupt working.\n"); + return ret; + } + + init_completion(&trng->rng_op_done); + + /* Enable interrupt for SW reset Health Check */ + val = readl(trng->base + TRNG_INTR_EN); + val |= RST_STARTUP_INITR_EN; + writel(val, trng->base + TRNG_INTR_EN); + + /* Set output to raw data */ + val = readl(trng->base + TRNG_NS_SEK_AND_DAT_EN); + val |= RAW_DATA_EN; + writel(val, trng->base + TRNG_NS_SEK_AND_DAT_EN); + + /* Put it in SW Reset */ + writel(SW_RST, trng->base + TRNG_HEALTH_TEST_SW_RST); + + trng->dev = dev; + trng->rng.name = pdev->name; + trng->rng.init = airoha_trng_init; + trng->rng.cleanup = airoha_trng_cleanup; + trng->rng.read = airoha_trng_read; + + ret = devm_hwrng_register(dev, &trng->rng); + if (ret) { + dev_err(dev, "failed to register rng device: %d\n", ret); + return ret; + } + + return 0; +} + +static const struct of_device_id airoha_trng_of_match[] = { + { .compatible = "airoha,en7581-trng", }, + {}, +}; +MODULE_DEVICE_TABLE(of, airoha_trng_of_match); + +static struct platform_driver airoha_trng_driver = { + .driver = { + .name = "airoha-trng", + .of_match_table = airoha_trng_of_match, + }, + .probe = airoha_trng_probe, +}; + +module_platform_driver(airoha_trng_driver); + +MODULE_LICENSE("GPL"); +MODULE_AUTHOR("Christian Marangi <ansuelsmth@gmail.com>"); +MODULE_DESCRIPTION("Airoha True Random Number Generator driver"); |