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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 <linux/acpi.h>
#include <linux/clk.h>
#include <linux/hw_random.h>
#include <linux/io.h>
#include <linux/iopoll.h>
#include <linux/kernel.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
#define QCOM_TRNG_QUALITY 1024
struct qcom_rng {
void __iomem *base;
struct clk *clk;
struct hwrng hwrng;
};
struct qcom_rng_match_data {
bool hwrng_support;
};
static int qcom_rng_read(struct qcom_rng *rng, u8 *data, unsigned int max)
{
unsigned int currsize = 0;
u32 val;
int ret;
/* read random data from hardware */
do {
ret = readl_poll_timeout(rng->base + PRNG_STATUS, val,
val & PRNG_STATUS_DATA_AVAIL,
200, 10000);
if (ret)
return ret;
val = readl_relaxed(rng->base + PRNG_DATA_OUT);
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);
currsize = max;
}
} while (currsize < max);
return currsize;
}
static int qcom_hwrng_init(struct hwrng *hwrng)
{
struct qcom_rng *qrng = container_of(hwrng, struct qcom_rng, hwrng);
return clk_prepare_enable(qrng->clk);
}
static int qcom_hwrng_read(struct hwrng *hwrng, void *data, size_t max, bool wait)
{
struct qcom_rng *qrng = container_of(hwrng, struct qcom_rng, hwrng);
return qcom_rng_read(qrng, data, max);
}
static void qcom_hwrng_cleanup(struct hwrng *hwrng)
{
struct qcom_rng *qrng = container_of(hwrng, struct qcom_rng, hwrng);
clk_disable_unprepare(qrng->clk);
}
static int qcom_rng_probe(struct platform_device *pdev)
{
const struct qcom_rng_match_data *match_data;
struct qcom_rng *rng;
int ret;
match_data = device_get_match_data(&pdev->dev);
if (match_data == NULL || !match_data->hwrng_support) {
dev_info(&pdev->dev, "TRNG support not detected\n");
/*
* In this case the driver does nothing except the dev_info(),
* but bind the device anyway to avoid effects on GCC state.
*/
return 0;
}
rng = devm_kzalloc(&pdev->dev, sizeof(*rng), GFP_KERNEL);
if (!rng)
return -ENOMEM;
rng->base = devm_platform_ioremap_resource(pdev, 0);
if (IS_ERR(rng->base))
return PTR_ERR(rng->base);
rng->clk = devm_clk_get_optional(&pdev->dev, "core");
if (IS_ERR(rng->clk))
return PTR_ERR(rng->clk);
rng->hwrng.name = "qcom_hwrng";
rng->hwrng.init = qcom_hwrng_init;
rng->hwrng.read = qcom_hwrng_read;
rng->hwrng.cleanup = qcom_hwrng_cleanup;
rng->hwrng.quality = QCOM_TRNG_QUALITY;
ret = devm_hwrng_register(&pdev->dev, &rng->hwrng);
if (ret)
dev_err(&pdev->dev, "Register hwrng failed: %d\n", ret);
return ret;
}
static struct qcom_rng_match_data qcom_prng_match_data = {
.hwrng_support = false,
};
static struct qcom_rng_match_data qcom_prng_ee_match_data = {
.hwrng_support = false,
};
static struct qcom_rng_match_data qcom_trng_match_data = {
.hwrng_support = true,
};
static const struct acpi_device_id __maybe_unused qcom_rng_acpi_match[] = {
{ .id = "QCOM8160", .driver_data = (kernel_ulong_t)&qcom_prng_ee_match_data },
{}
};
MODULE_DEVICE_TABLE(acpi, qcom_rng_acpi_match);
static const struct of_device_id __maybe_unused qcom_rng_of_match[] = {
{ .compatible = "qcom,prng", .data = &qcom_prng_match_data },
{ .compatible = "qcom,prng-ee", .data = &qcom_prng_ee_match_data },
{ .compatible = "qcom,trng", .data = &qcom_trng_match_data },
{}
};
MODULE_DEVICE_TABLE(of, qcom_rng_of_match);
static struct platform_driver qcom_rng_driver = {
.probe = qcom_rng_probe,
.driver = {
.name = KBUILD_MODNAME,
.of_match_table = 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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