1422e36351
Use dev_err_probe to print the error message after a failed hwrng registration. Signed-off-by: Martin Kaiser <martin@kaiser.cx> Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
220 lines
5.2 KiB
C
220 lines
5.2 KiB
C
// SPDX-License-Identifier: GPL-2.0
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// Copyright (c) 2020 Silex Insight
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#include <linux/delay.h>
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#include <linux/hw_random.h>
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#include <linux/io.h>
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#include <linux/iopoll.h>
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#include <linux/kernel.h>
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#include <linux/mod_devicetable.h>
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#include <linux/module.h>
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#include <linux/platform_device.h>
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#include <linux/workqueue.h>
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#define BA431_RESET_DELAY 1 /* usec */
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#define BA431_RESET_READ_STATUS_TIMEOUT 1000 /* usec */
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#define BA431_RESET_READ_STATUS_INTERVAL 10 /* usec */
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#define BA431_READ_RETRY_INTERVAL 1 /* usec */
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#define BA431_REG_CTRL 0x00
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#define BA431_REG_FIFO_LEVEL 0x04
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#define BA431_REG_STATUS 0x30
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#define BA431_REG_FIFODATA 0x80
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#define BA431_CTRL_ENABLE BIT(0)
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#define BA431_CTRL_SOFTRESET BIT(8)
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#define BA431_STATUS_STATE_MASK (BIT(1) | BIT(2) | BIT(3))
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#define BA431_STATUS_STATE_OFFSET 1
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enum ba431_state {
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BA431_STATE_RESET,
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BA431_STATE_STARTUP,
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BA431_STATE_FIFOFULLON,
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BA431_STATE_FIFOFULLOFF,
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BA431_STATE_RUNNING,
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BA431_STATE_ERROR
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};
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struct ba431_trng {
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struct device *dev;
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void __iomem *base;
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struct hwrng rng;
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atomic_t reset_pending;
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struct work_struct reset_work;
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};
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static inline u32 ba431_trng_read_reg(struct ba431_trng *ba431, u32 reg)
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{
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return ioread32(ba431->base + reg);
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}
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static inline void ba431_trng_write_reg(struct ba431_trng *ba431, u32 reg,
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u32 val)
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{
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iowrite32(val, ba431->base + reg);
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}
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static inline enum ba431_state ba431_trng_get_state(struct ba431_trng *ba431)
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{
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u32 status = ba431_trng_read_reg(ba431, BA431_REG_STATUS);
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return (status & BA431_STATUS_STATE_MASK) >> BA431_STATUS_STATE_OFFSET;
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}
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static int ba431_trng_is_in_error(struct ba431_trng *ba431)
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{
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enum ba431_state state = ba431_trng_get_state(ba431);
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if ((state < BA431_STATE_STARTUP) ||
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(state >= BA431_STATE_ERROR))
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return 1;
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return 0;
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}
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static int ba431_trng_reset(struct ba431_trng *ba431)
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{
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int ret;
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/* Disable interrupts, random generation and enable the softreset */
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ba431_trng_write_reg(ba431, BA431_REG_CTRL, BA431_CTRL_SOFTRESET);
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udelay(BA431_RESET_DELAY);
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ba431_trng_write_reg(ba431, BA431_REG_CTRL, BA431_CTRL_ENABLE);
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/* Wait until the state changed */
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if (readx_poll_timeout(ba431_trng_is_in_error, ba431, ret, !ret,
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BA431_RESET_READ_STATUS_INTERVAL,
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BA431_RESET_READ_STATUS_TIMEOUT)) {
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dev_err(ba431->dev, "reset failed (state: %d)\n",
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ba431_trng_get_state(ba431));
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return -ETIMEDOUT;
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}
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dev_info(ba431->dev, "reset done\n");
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return 0;
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}
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static void ba431_trng_reset_work(struct work_struct *work)
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{
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struct ba431_trng *ba431 = container_of(work, struct ba431_trng,
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reset_work);
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ba431_trng_reset(ba431);
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atomic_set(&ba431->reset_pending, 0);
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}
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static void ba431_trng_schedule_reset(struct ba431_trng *ba431)
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{
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if (atomic_cmpxchg(&ba431->reset_pending, 0, 1))
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return;
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schedule_work(&ba431->reset_work);
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}
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static int ba431_trng_read(struct hwrng *rng, void *buf, size_t max, bool wait)
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{
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struct ba431_trng *ba431 = container_of(rng, struct ba431_trng, rng);
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u32 *data = buf;
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unsigned int level, i;
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int n = 0;
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while (max > 0) {
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level = ba431_trng_read_reg(ba431, BA431_REG_FIFO_LEVEL);
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if (!level) {
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if (ba431_trng_is_in_error(ba431)) {
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ba431_trng_schedule_reset(ba431);
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break;
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}
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if (!wait)
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break;
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udelay(BA431_READ_RETRY_INTERVAL);
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continue;
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}
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i = level;
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do {
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data[n++] = ba431_trng_read_reg(ba431,
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BA431_REG_FIFODATA);
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max -= sizeof(*data);
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} while (--i && (max > 0));
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if (ba431_trng_is_in_error(ba431)) {
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n -= (level - i);
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ba431_trng_schedule_reset(ba431);
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break;
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}
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}
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n *= sizeof(data);
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return (n || !wait) ? n : -EIO;
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}
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static void ba431_trng_cleanup(struct hwrng *rng)
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{
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struct ba431_trng *ba431 = container_of(rng, struct ba431_trng, rng);
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ba431_trng_write_reg(ba431, BA431_REG_CTRL, 0);
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cancel_work_sync(&ba431->reset_work);
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}
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static int ba431_trng_init(struct hwrng *rng)
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{
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struct ba431_trng *ba431 = container_of(rng, struct ba431_trng, rng);
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return ba431_trng_reset(ba431);
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}
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static int ba431_trng_probe(struct platform_device *pdev)
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{
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struct ba431_trng *ba431;
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int ret;
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ba431 = devm_kzalloc(&pdev->dev, sizeof(*ba431), GFP_KERNEL);
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if (!ba431)
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return -ENOMEM;
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ba431->dev = &pdev->dev;
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ba431->base = devm_platform_ioremap_resource(pdev, 0);
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if (IS_ERR(ba431->base))
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return PTR_ERR(ba431->base);
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atomic_set(&ba431->reset_pending, 0);
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INIT_WORK(&ba431->reset_work, ba431_trng_reset_work);
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ba431->rng.name = pdev->name;
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ba431->rng.init = ba431_trng_init;
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ba431->rng.cleanup = ba431_trng_cleanup;
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ba431->rng.read = ba431_trng_read;
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ret = devm_hwrng_register(&pdev->dev, &ba431->rng);
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if (ret)
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return dev_err_probe(&pdev->dev, ret, "BA431 registration failed\n");
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dev_info(&pdev->dev, "BA431 TRNG registered\n");
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return 0;
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}
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static const struct of_device_id ba431_trng_dt_ids[] = {
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{ .compatible = "silex-insight,ba431-rng" },
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{ /* sentinel */ }
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};
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MODULE_DEVICE_TABLE(of, ba431_trng_dt_ids);
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static struct platform_driver ba431_trng_driver = {
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.driver = {
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.name = "ba431-rng",
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.of_match_table = ba431_trng_dt_ids,
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},
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.probe = ba431_trng_probe,
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};
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module_platform_driver(ba431_trng_driver);
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MODULE_AUTHOR("Olivier Sobrie <olivier@sobrie.be>");
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MODULE_DESCRIPTION("TRNG driver for Silex Insight BA431");
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MODULE_LICENSE("GPL");
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