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// SPDX-License-Identifier: GPL-2.0
// Copyright (c) 2017-18 Linaro Limited
//
// Based on msm-rng.c and downstream driver
#include <crypto/internal/rng.h>
#include <linux/acpi.h>
#include <linux/clk.h>
#include <linux/crypto.h>
#include <linux/module.h>
#include <linux/of.h>
#include <linux/platform_device.h>
/* Device specific register offsets */
#define PRNG_DATA_OUT 0x0000
#define PRNG_STATUS 0x0004
#define PRNG_LFSR_CFG 0x0100
#define PRNG_CONFIG 0x0104
/* Device specific register masks and config values */
#define PRNG_LFSR_CFG_MASK 0x0000ffff
#define PRNG_LFSR_CFG_CLOCKS 0x0000dddd
#define PRNG_CONFIG_HW_ENABLE BIT(1)
#define PRNG_STATUS_DATA_AVAIL BIT(0)
#define WORD_SZ 4
struct qcom_rng {
struct mutex lock;
void __iomem *base;
struct clk *clk;
unsigned int skip_init;
};
struct qcom_rng_ctx {
struct qcom_rng *rng;
};
static struct qcom_rng *qcom_rng_dev;
static int qcom_rng_read(struct qcom_rng *rng, u8 *data, unsigned int max)
{
unsigned int currsize = 0;
u32 val;
/* read random data from hardware */
do {
val = readl_relaxed(rng->base + PRNG_STATUS);
if (!(val & PRNG_STATUS_DATA_AVAIL))
break;
val = readl_relaxed(rng->base + PRNG_DATA_OUT);
if (!val)
break;
if ((max - currsize) >= WORD_SZ) {
memcpy(data, &val, WORD_SZ);
data += WORD_SZ;
currsize += WORD_SZ;
} else {
/* copy only remaining bytes */
memcpy(data, &val, max - currsize);
break;
}
} while (currsize < max);
return currsize;
}
static int qcom_rng_generate(struct crypto_rng *tfm,
const u8 *src, unsigned int slen,
u8 *dstn, unsigned int dlen)
{
struct qcom_rng_ctx *ctx = crypto_rng_ctx(tfm);
struct qcom_rng *rng = ctx->rng;
int ret;
ret = clk_prepare_enable(rng->clk);
if (ret)
return ret;
mutex_lock(&rng->lock);
ret = qcom_rng_read(rng, dstn, dlen);
mutex_unlock(&rng->lock);
clk_disable_unprepare(rng->clk);
return 0;
}
static int qcom_rng_seed(struct crypto_rng *tfm, const u8 *seed,
unsigned int slen)
{
return 0;
}
static int qcom_rng_enable(struct qcom_rng *rng)
{
u32 val;
int ret;
ret = clk_prepare_enable(rng->clk);
if (ret)
return ret;
/* Enable PRNG only if it is not already enabled */
val = readl_relaxed(rng->base + PRNG_CONFIG);
if (val & PRNG_CONFIG_HW_ENABLE)
goto already_enabled;
val = readl_relaxed(rng->base + PRNG_LFSR_CFG);
val &= ~PRNG_LFSR_CFG_MASK;
val |= PRNG_LFSR_CFG_CLOCKS;
writel(val, rng->base + PRNG_LFSR_CFG);
val = readl_relaxed(rng->base + PRNG_CONFIG);
val |= PRNG_CONFIG_HW_ENABLE;
writel(val, rng->base + PRNG_CONFIG);
already_enabled:
clk_disable_unprepare(rng->clk);
return 0;
}
static int qcom_rng_init(struct crypto_tfm *tfm)
{
struct qcom_rng_ctx *ctx = crypto_tfm_ctx(tfm);
ctx->rng = qcom_rng_dev;
if (!ctx->rng->skip_init)
return qcom_rng_enable(ctx->rng);
return 0;
}
static struct rng_alg qcom_rng_alg = {
.generate = qcom_rng_generate,
.seed = qcom_rng_seed,
.seedsize = 0,
.base = {
.cra_name = "stdrng",
.cra_driver_name = "qcom-rng",
.cra_flags = CRYPTO_ALG_TYPE_RNG,
.cra_priority = 300,
.cra_ctxsize = sizeof(struct qcom_rng_ctx),
.cra_module = THIS_MODULE,
.cra_init = qcom_rng_init,
}
};
static int qcom_rng_probe(struct platform_device *pdev)
{
struct qcom_rng *rng;
int ret;
rng = devm_kzalloc(&pdev->dev, sizeof(*rng), GFP_KERNEL);
if (!rng)
return -ENOMEM;
platform_set_drvdata(pdev, rng);
mutex_init(&rng->lock);
rng->base = devm_platform_ioremap_resource(pdev, 0);
if (IS_ERR(rng->base))
return PTR_ERR(rng->base);
/* ACPI systems have clk already on, so skip clk_get */
if (!has_acpi_companion(&pdev->dev)) {
rng->clk = devm_clk_get(&pdev->dev, "core");
if (IS_ERR(rng->clk))
return PTR_ERR(rng->clk);
}
rng->skip_init = (unsigned long)device_get_match_data(&pdev->dev);
qcom_rng_dev = rng;
ret = crypto_register_rng(&qcom_rng_alg);
if (ret) {
dev_err(&pdev->dev, "Register crypto rng failed: %d\n", ret);
qcom_rng_dev = NULL;
}
return ret;
}
static int qcom_rng_remove(struct platform_device *pdev)
{
crypto_unregister_rng(&qcom_rng_alg);
qcom_rng_dev = NULL;
return 0;
}
#if IS_ENABLED(CONFIG_ACPI)
static const struct acpi_device_id qcom_rng_acpi_match[] = {
{ .id = "QCOM8160", .driver_data = 1 },
{}
};
MODULE_DEVICE_TABLE(acpi, qcom_rng_acpi_match);
#endif
static const struct of_device_id qcom_rng_of_match[] = {
{ .compatible = "qcom,prng", .data = (void *)0},
{ .compatible = "qcom,prng-ee", .data = (void *)1},
{}
};
MODULE_DEVICE_TABLE(of, qcom_rng_of_match);
static struct platform_driver qcom_rng_driver = {
.probe = qcom_rng_probe,
.remove = qcom_rng_remove,
.driver = {
.name = KBUILD_MODNAME,
.of_match_table = of_match_ptr(qcom_rng_of_match),
.acpi_match_table = ACPI_PTR(qcom_rng_acpi_match),
}
};
module_platform_driver(qcom_rng_driver);
MODULE_ALIAS("platform:" KBUILD_MODNAME);
MODULE_DESCRIPTION("Qualcomm random number generator driver");
MODULE_LICENSE("GPL v2");
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