linux/drivers/crypto/qcom-rng.c
Timur Tabi d96542ac10 crypto: qcom-rng - Add ACPI support
Add support for probing on ACPI systems, with ACPI HID QCOM8160.

On ACPI systems, clocks are always enabled, the PRNG should
already be enabled, and the register region is read-only.
The driver only verifies that the hardware is already
enabled never tries to disable or configure it.

Signed-off-by: Timur Tabi <timur@codeaurora.org>
Tested-by: Jeffrey Hugo <jhugo@codeaurora.org>
[port to crypto API]
Signed-off-by: Vinod Koul <vkoul@kernel.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
2018-07-27 19:04:32 +08:00

230 lines
4.9 KiB
C

// 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 resource *res;
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);
res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
rng->base = devm_ioremap_resource(&pdev->dev, res);
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");