1 // SPDX-License-Identifier: GPL-2.0
2 /* Copyright (C) 2024 Christian Marangi */
4 #include <linux/kernel.h>
5 #include <linux/module.h>
6 #include <linux/mod_devicetable.h>
7 #include <linux/bitfield.h>
8 #include <linux/delay.h>
9 #include <linux/hw_random.h>
10 #include <linux/interrupt.h>
12 #include <linux/iopoll.h>
13 #include <linux/platform_device.h>
15 #define TRNG_IP_RDY 0x800
16 #define CNT_TRANS GENMASK(15, 8)
17 #define SAMPLE_RDY BIT(0)
18 #define TRNG_NS_SEK_AND_DAT_EN 0x804
19 #define RNG_EN BIT(31) /* referenced as ring_en */
20 #define RAW_DATA_EN BIT(16)
21 #define TRNG_HEALTH_TEST_SW_RST 0x808
22 #define SW_RST BIT(0) /* Active High */
23 #define TRNG_INTR_EN 0x818
24 #define INTR_MASK BIT(16)
25 #define CONTINUOUS_HEALTH_INITR_EN BIT(2)
26 #define SW_STARTUP_INITR_EN BIT(1)
27 #define RST_STARTUP_INITR_EN BIT(0)
28 /* Notice that Health Test are done only out of Reset and with RNG_EN */
29 #define TRNG_HEALTH_TEST_STATUS 0x824
30 #define CONTINUOUS_HEALTH_AP_TEST_FAIL BIT(23)
31 #define CONTINUOUS_HEALTH_RC_TEST_FAIL BIT(22)
32 #define SW_STARTUP_TEST_DONE BIT(21)
33 #define SW_STARTUP_AP_TEST_FAIL BIT(20)
34 #define SW_STARTUP_RC_TEST_FAIL BIT(19)
35 #define RST_STARTUP_TEST_DONE BIT(18)
36 #define RST_STARTUP_AP_TEST_FAIL BIT(17)
37 #define RST_STARTUP_RC_TEST_FAIL BIT(16)
38 #define RAW_DATA_VALID BIT(7)
40 #define TRNG_RAW_DATA_OUT 0x828
42 #define TRNG_CNT_TRANS_VALID 0x80
43 #define BUSY_LOOP_SLEEP 10
44 #define BUSY_LOOP_TIMEOUT (BUSY_LOOP_SLEEP * 10000)
51 struct completion rng_op_done;
54 static int airoha_trng_irq_mask(struct airoha_trng *trng)
58 val = readl(trng->base + TRNG_INTR_EN);
60 writel(val, trng->base + TRNG_INTR_EN);
65 static int airoha_trng_irq_unmask(struct airoha_trng *trng)
69 val = readl(trng->base + TRNG_INTR_EN);
71 writel(val, trng->base + TRNG_INTR_EN);
76 static int airoha_trng_init(struct hwrng *rng)
78 struct airoha_trng *trng = container_of(rng, struct airoha_trng, rng);
82 val = readl(trng->base + TRNG_NS_SEK_AND_DAT_EN);
84 writel(val, trng->base + TRNG_NS_SEK_AND_DAT_EN);
86 /* Set out of SW Reset */
87 airoha_trng_irq_unmask(trng);
88 writel(0, trng->base + TRNG_HEALTH_TEST_SW_RST);
90 ret = wait_for_completion_timeout(&trng->rng_op_done, BUSY_LOOP_TIMEOUT);
92 dev_err(trng->dev, "Timeout waiting for Health Check\n");
93 airoha_trng_irq_mask(trng);
97 /* Check if Health Test Failed */
98 val = readl(trng->base + TRNG_HEALTH_TEST_STATUS);
99 if (val & (RST_STARTUP_AP_TEST_FAIL | RST_STARTUP_RC_TEST_FAIL)) {
100 dev_err(trng->dev, "Health Check fail: %s test fail\n",
101 val & RST_STARTUP_AP_TEST_FAIL ? "AP" : "RC");
105 /* Check if IP is ready */
106 ret = readl_poll_timeout(trng->base + TRNG_IP_RDY, val,
107 val & SAMPLE_RDY, 10, 1000);
109 dev_err(trng->dev, "Timeout waiting for IP ready");
113 /* CNT_TRANS must be 0x80 for IP to be considered ready */
114 ret = readl_poll_timeout(trng->base + TRNG_IP_RDY, val,
115 FIELD_GET(CNT_TRANS, val) == TRNG_CNT_TRANS_VALID,
118 dev_err(trng->dev, "Timeout waiting for IP ready");
125 static void airoha_trng_cleanup(struct hwrng *rng)
127 struct airoha_trng *trng = container_of(rng, struct airoha_trng, rng);
130 val = readl(trng->base + TRNG_NS_SEK_AND_DAT_EN);
132 writel(val, trng->base + TRNG_NS_SEK_AND_DAT_EN);
134 /* Put it in SW Reset */
135 writel(SW_RST, trng->base + TRNG_HEALTH_TEST_SW_RST);
138 static int airoha_trng_read(struct hwrng *rng, void *buf, size_t max, bool wait)
140 struct airoha_trng *trng = container_of(rng, struct airoha_trng, rng);
145 ret = readl_poll_timeout(trng->base + TRNG_HEALTH_TEST_STATUS, status,
146 status & RAW_DATA_VALID, 10, 1000);
148 dev_err(trng->dev, "Timeout waiting for TRNG RAW Data valid\n");
152 *data = readl(trng->base + TRNG_RAW_DATA_OUT);
157 static irqreturn_t airoha_trng_irq(int irq, void *priv)
159 struct airoha_trng *trng = (struct airoha_trng *)priv;
161 airoha_trng_irq_mask(trng);
162 /* Just complete the task, we will read the value later */
163 complete(&trng->rng_op_done);
168 static int airoha_trng_probe(struct platform_device *pdev)
170 struct device *dev = &pdev->dev;
171 struct airoha_trng *trng;
175 trng = devm_kzalloc(dev, sizeof(*trng), GFP_KERNEL);
179 trng->base = devm_platform_ioremap_resource(pdev, 0);
180 if (IS_ERR(trng->base))
181 return PTR_ERR(trng->base);
183 irq = platform_get_irq(pdev, 0);
187 airoha_trng_irq_mask(trng);
188 ret = devm_request_irq(&pdev->dev, irq, airoha_trng_irq, 0,
189 pdev->name, (void *)trng);
191 dev_err(dev, "Can't get interrupt working.\n");
195 init_completion(&trng->rng_op_done);
197 /* Enable interrupt for SW reset Health Check */
198 val = readl(trng->base + TRNG_INTR_EN);
199 val |= RST_STARTUP_INITR_EN;
200 writel(val, trng->base + TRNG_INTR_EN);
202 /* Set output to raw data */
203 val = readl(trng->base + TRNG_NS_SEK_AND_DAT_EN);
205 writel(val, trng->base + TRNG_NS_SEK_AND_DAT_EN);
207 /* Put it in SW Reset */
208 writel(SW_RST, trng->base + TRNG_HEALTH_TEST_SW_RST);
211 trng->rng.name = pdev->name;
212 trng->rng.init = airoha_trng_init;
213 trng->rng.cleanup = airoha_trng_cleanup;
214 trng->rng.read = airoha_trng_read;
216 ret = devm_hwrng_register(dev, &trng->rng);
218 dev_err(dev, "failed to register rng device: %d\n", ret);
225 static const struct of_device_id airoha_trng_of_match[] = {
226 { .compatible = "airoha,en7581-trng", },
229 MODULE_DEVICE_TABLE(of, airoha_trng_of_match);
231 static struct platform_driver airoha_trng_driver = {
233 .name = "airoha-trng",
234 .of_match_table = airoha_trng_of_match,
236 .probe = airoha_trng_probe,
239 module_platform_driver(airoha_trng_driver);
241 MODULE_LICENSE("GPL");
243 MODULE_DESCRIPTION("Airoha True Random Number Generator driver");