--- /dev/null
+// 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");
projects / thirdparty / kernel / linux.git / commitdiff
