--- /dev/null
+// SPDX-License-Identifier: GPL-2.0
+// Copyright (c) 2020 Silex Insight
+
+#include <linux/delay.h>
+#include <linux/hw_random.h>
+#include <linux/io.h>
+#include <linux/iopoll.h>
+#include <linux/mod_devicetable.h>
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/workqueue.h>
+
+#define BA431_RESET_DELAY 1 /* usec */
+#define BA431_RESET_READ_STATUS_TIMEOUT 1000 /* usec */
+#define BA431_RESET_READ_STATUS_INTERVAL 10 /* usec */
+#define BA431_READ_RETRY_INTERVAL 1 /* usec */
+
+#define BA431_REG_CTRL 0x00
+#define BA431_REG_FIFO_LEVEL 0x04
+#define BA431_REG_STATUS 0x30
+#define BA431_REG_FIFODATA 0x80
+
+#define BA431_CTRL_ENABLE BIT(0)
+#define BA431_CTRL_SOFTRESET BIT(8)
+
+#define BA431_STATUS_STATE_MASK (BIT(1) | BIT(2) | BIT(3))
+#define BA431_STATUS_STATE_OFFSET 1
+
+enum ba431_state {
+ BA431_STATE_RESET,
+ BA431_STATE_STARTUP,
+ BA431_STATE_FIFOFULLON,
+ BA431_STATE_FIFOFULLOFF,
+ BA431_STATE_RUNNING,
+ BA431_STATE_ERROR
+};
+
+struct ba431_trng {
+ struct device *dev;
+ void __iomem *base;
+ struct hwrng rng;
+ atomic_t reset_pending;
+ struct work_struct reset_work;
+};
+
+static inline u32 ba431_trng_read_reg(struct ba431_trng *ba431, u32 reg)
+{
+ return ioread32(ba431->base + reg);
+}
+
+static inline void ba431_trng_write_reg(struct ba431_trng *ba431, u32 reg,
+ u32 val)
+{
+ iowrite32(val, ba431->base + reg);
+}
+
+static inline enum ba431_state ba431_trng_get_state(struct ba431_trng *ba431)
+{
+ u32 status = ba431_trng_read_reg(ba431, BA431_REG_STATUS);
+
+ return (status & BA431_STATUS_STATE_MASK) >> BA431_STATUS_STATE_OFFSET;
+}
+
+static int ba431_trng_is_in_error(struct ba431_trng *ba431)
+{
+ enum ba431_state state = ba431_trng_get_state(ba431);
+
+ if ((state < BA431_STATE_STARTUP) ||
+ (state >= BA431_STATE_ERROR))
+ return 1;
+
+ return 0;
+}
+
+static int ba431_trng_reset(struct ba431_trng *ba431)
+{
+ int ret;
+
+ /* Disable interrupts, random generation and enable the softreset */
+ ba431_trng_write_reg(ba431, BA431_REG_CTRL, BA431_CTRL_SOFTRESET);
+ udelay(BA431_RESET_DELAY);
+ ba431_trng_write_reg(ba431, BA431_REG_CTRL, BA431_CTRL_ENABLE);
+
+ /* Wait until the state changed */
+ if (readx_poll_timeout(ba431_trng_is_in_error, ba431, ret, !ret,
+ BA431_RESET_READ_STATUS_INTERVAL,
+ BA431_RESET_READ_STATUS_TIMEOUT)) {
+ dev_err(ba431->dev, "reset failed (state: %d)\n",
+ ba431_trng_get_state(ba431));
+ return -ETIMEDOUT;
+ }
+
+ dev_info(ba431->dev, "reset done\n");
+
+ return 0;
+}
+
+static void ba431_trng_reset_work(struct work_struct *work)
+{
+ struct ba431_trng *ba431 = container_of(work, struct ba431_trng,
+ reset_work);
+ ba431_trng_reset(ba431);
+ atomic_set(&ba431->reset_pending, 0);
+}
+
+static void ba431_trng_schedule_reset(struct ba431_trng *ba431)
+{
+ if (atomic_cmpxchg(&ba431->reset_pending, 0, 1))
+ return;
+
+ schedule_work(&ba431->reset_work);
+}
+
+static int ba431_trng_read(struct hwrng *rng, void *buf, size_t max, bool wait)
+{
+ struct ba431_trng *ba431 = container_of(rng, struct ba431_trng, rng);
+ u32 *data = buf;
+ unsigned int level, i;
+ int n = 0;
+
+ while (max > 0) {
+ level = ba431_trng_read_reg(ba431, BA431_REG_FIFO_LEVEL);
+ if (!level) {
+ if (ba431_trng_is_in_error(ba431)) {
+ ba431_trng_schedule_reset(ba431);
+ break;
+ }
+
+ if (!wait)
+ break;
+
+ udelay(BA431_READ_RETRY_INTERVAL);
+ continue;
+ }
+
+ i = level;
+ do {
+ data[n++] = ba431_trng_read_reg(ba431,
+ BA431_REG_FIFODATA);
+ max -= sizeof(*data);
+ } while (--i && (max > 0));
+
+ if (ba431_trng_is_in_error(ba431)) {
+ n -= (level - i);
+ ba431_trng_schedule_reset(ba431);
+ break;
+ }
+ }
+
+ n *= sizeof(data);
+ return (n || !wait) ? n : -EIO;
+}
+
+static void ba431_trng_cleanup(struct hwrng *rng)
+{
+ struct ba431_trng *ba431 = container_of(rng, struct ba431_trng, rng);
+
+ ba431_trng_write_reg(ba431, BA431_REG_CTRL, 0);
+ cancel_work_sync(&ba431->reset_work);
+}
+
+static int ba431_trng_init(struct hwrng *rng)
+{
+ struct ba431_trng *ba431 = container_of(rng, struct ba431_trng, rng);
+
+ return ba431_trng_reset(ba431);
+}
+
+static int ba431_trng_probe(struct platform_device *pdev)
+{
+ struct ba431_trng *ba431;
+ struct resource *res;
+ int ret;
+
+ ba431 = devm_kzalloc(&pdev->dev, sizeof(*ba431), GFP_KERNEL);
+ if (!ba431)
+ return -ENOMEM;
+
+ ba431->dev = &pdev->dev;
+
+ res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+ ba431->base = devm_ioremap_resource(&pdev->dev, res);
+ if (IS_ERR(ba431->base))
+ return PTR_ERR(ba431->base);
+
+ atomic_set(&ba431->reset_pending, 0);
+ INIT_WORK(&ba431->reset_work, ba431_trng_reset_work);
+ ba431->rng.name = pdev->name;
+ ba431->rng.init = ba431_trng_init;
+ ba431->rng.cleanup = ba431_trng_cleanup;
+ ba431->rng.read = ba431_trng_read;
+
+ platform_set_drvdata(pdev, ba431);
+
+ ret = hwrng_register(&ba431->rng);
+ if (ret) {
+ dev_err(&pdev->dev, "BA431 registration failed (%d)\n", ret);
+ return ret;
+ }
+
+ dev_info(&pdev->dev, "BA431 TRNG registered\n");
+
+ return 0;
+}
+
+static int ba431_trng_remove(struct platform_device *pdev)
+{
+ struct ba431_trng *ba431 = platform_get_drvdata(pdev);
+
+ hwrng_unregister(&ba431->rng);
+
+ return 0;
+}
+
+static const struct of_device_id ba431_trng_dt_ids[] = {
+ { .compatible = "silex-insight,ba431-rng", .data = NULL },
+ { /* sentinel */ }
+};
+MODULE_DEVICE_TABLE(of, ba431_trng_dt_ids);
+
+static struct platform_driver ba431_trng_driver = {
+ .driver = {
+ .name = "ba431-rng",
+ .of_match_table = ba431_trng_dt_ids,
+ },
+ .probe = ba431_trng_probe,
+ .remove = ba431_trng_remove,
+};
+
+module_platform_driver(ba431_trng_driver);
+
+MODULE_AUTHOR("Olivier Sobrie <olivier@sobrie.be>");
+MODULE_DESCRIPTION("TRNG driver for Silex Insight BA431");
+MODULE_LICENSE("GPL");
projects / nvme.git / commitdiff