/*
* APM X-Gene SoC RNG Driver
*
* Copyright (c) 2014, Applied Micro Circuits Corporation
* Author: Rameshwar Prasad Sahu <rsahu@apm.com>
* Shamal Winchurkar <swinchurkar@apm.com>
* Feng Kan <fkan@apm.com>
*
* This program is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License as published by the
* Free Software Foundation; either version 2 of the License, or (at your
* option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*
*/
#include <linux/acpi.h>
#include <linux/clk.h>
#include <linux/delay.h>
#include <linux/hw_random.h>
#include <linux/init.h>
#include <linux/interrupt.h>
#include <linux/module.h>
#include <linux/of_platform.h>
#include <linux/of_irq.h>
#include <linux/of_address.h>
#include <linux/timer.h>
#define RNG_MAX_DATUM 4
#define MAX_TRY 100
#define XGENE_RNG_RETRY_COUNT 20
#define XGENE_RNG_RETRY_INTERVAL 10
/* RNG Registers */
#define RNG_INOUT_0 0x00
#define RNG_INTR_STS_ACK 0x10
#define RNG_CONTROL 0x14
#define RNG_CONFIG 0x18
#define RNG_ALARMCNT 0x1c
#define RNG_FROENABLE 0x20
#define RNG_FRODETUNE 0x24
#define RNG_ALARMMASK 0x28
#define RNG_ALARMSTOP 0x2c
#define RNG_OPTIONS 0x78
#define RNG_EIP_REV 0x7c
#define MONOBIT_FAIL_MASK BIT(7)
#define POKER_FAIL_MASK BIT(6)
#define LONG_RUN_FAIL_MASK BIT(5)
#define RUN_FAIL_MASK BIT(4)
#define NOISE_FAIL_MASK BIT(3)
#define STUCK_OUT_MASK BIT(2)
#define SHUTDOWN_OFLO_MASK BIT(1)
#define READY_MASK BIT(0)
#define MAJOR_HW_REV_RD(src) (((src) & 0x0f000000) >> 24)
#define MINOR_HW_REV_RD(src) (((src) & 0x00f00000) >> 20)
#define HW_PATCH_LEVEL_RD(src) (((src) & 0x000f0000) >> 16)
#define MAX_REFILL_CYCLES_SET(dst, src) \
((dst & ~0xffff0000) | (((u32)src << 16) & 0xffff0000))
#define MIN_REFILL_CYCLES_SET(dst, src) \
((dst & ~0x000000ff) | (((u32)src) & 0x000000ff))
#define ALARM_THRESHOLD_SET(dst, src) \
((dst & ~0x000000ff) | (((u32)src) & 0x000000ff))
#define ENABLE_RNG_SET(dst, src) \
((dst & ~BIT(10)) | (((u32)src << 10) & BIT(10)))
#define REGSPEC_TEST_MODE_SET(dst, src) \
((dst & ~BIT(8)) | (((u32)src << 8) & BIT(8)))
#define MONOBIT_FAIL_MASK_SET(dst, src) \
((dst & ~BIT(7)) | (((u32)src << 7) & BIT(7)))
#define POKER_FAIL_MASK_SET(dst, src) \
((dst & ~BIT(6)) | (((u32)src << 6) & BIT(6)))
#define LONG_RUN_FAIL_MASK_SET(dst, src) \
((dst & ~BIT(5)) | (((u32)src << 5) & BIT(5)))
#define RUN_FAIL_MASK_SET(dst, src) \
((dst & ~BIT(4)) | (((u32)src << 4) & BIT(4)))
#define NOISE_FAIL_MASK_SET(dst, src) \
((dst & ~BIT(3)) | (((u32)src << 3) & BIT(3)))
#define STUCK_OUT_MASK_SET(dst, src) \
((dst & ~BIT(2)) | (((u32)src << 2) & BIT(2)))
#define SHUTDOWN_OFLO_MASK_SET(dst, src) \
((dst & ~BIT(1)) | (((u32)src << 1) & BIT(1)))
struct xgene_rng_dev {
u32 irq;
void __iomem *csr_base;
u32 revision;
u32 datum_size;
u32 failure_cnt; /* Failure count last minute */
unsigned long failure_ts;/* First failure timestamp */
struct timer_list failure_timer;
struct device *dev;
struct clk *clk;
};
static void xgene_rng_expired_timer(unsigned long arg)
{
struct xgene_rng_dev *ctx = (struct xgene_rng_dev *) arg;
/* Clear failure counter as timer expired */
disable_irq(ctx->irq);
ctx->failure_cnt = 0;
del_timer(&ctx->failure_timer);
enable_irq(ctx->irq);
}
static void xgene_rng_start_timer(struct xgene_rng_dev *ctx)
{
ctx->failure_timer.data = (unsigned long) ctx;
ctx->failure_timer.function = xgene_rng_expired_timer;
ctx->failure_timer.expires = jiffies + 120 * HZ;
add_timer(&ctx->failure_timer);
}
/*
* Initialize or reinit free running oscillators (FROs)
*/
static void xgene_rng_init_fro(struct xgene_rng_dev *ctx, u32 fro_val)
{
writel(fro_val, ctx->csr_base + RNG_FRODETUNE);
writel(0x00000000, ctx->csr_base + RNG_ALARMMASK);
writel(0x00000000, ctx->csr_base + RNG_ALARMSTOP);
writel(0xFFFFFFFF, ctx->csr_base + RNG_FROENABLE);
}
static void xgene_rng_chk_overflow(struct xgene_rng_dev *ctx)
{
u32 val;
val = readl(ctx->csr_base + RNG_INTR_STS_ACK);
if (val & MONOBIT_FAIL_MASK)
/*
* LFSR detected an out-of-bounds number of 1s after
* checking 20,000 bits (test T1 as specified in the
* AIS-31 standard)
*/
dev_err(ctx->dev, "test monobit failure error 0x%08X\n", val);
if (val & POKER_FAIL_MASK)
/*
* LFSR detected an out-of-bounds value in at least one
* of the 16 poker_count_X counters or an out of bounds sum
* of squares value after checking 20,000 bits (test T2 as
* specified in the AIS-31 standard)
*/
dev_err(ctx->dev, "test poker failure error 0x%08X\n", val);
if (val & LONG_RUN_FAIL_MASK)
/*
* LFSR detected a sequence of 34 identical bits
* (test T4 as specified in the AIS-31 standard)
*/
dev_err(ctx->dev, "test long run failure error 0x%08X\n", val);
if (val & RUN_FAIL_MASK)
/*
* LFSR detected an outof-bounds value for at least one
* of the running counters after checking 20,000 bits
* (test T3 as specified in the AIS-31 standard)
*/
dev_err(ctx->dev, "test run failure error 0x%08X\n", val);
if (val & NOISE_FAIL_MASK)
/* LFSR detected a sequence of 48 identical bits */
dev_err(ctx->dev, "noise failure error 0x%08X\n", val);
if (val & STUCK_OUT_MASK)
/*
* Detected output data registers generated same value twice
* in a row
*/
dev_err(ctx->dev, "stuck out failure error 0x%08X\n", val);
if (val & SHUTDOWN_OFLO_MASK) {
u32 frostopped;
/* FROs shut down after a second error event. Try recover. */
if (++ctx->failure_cnt == 1) {
/* 1st time, just recover */
ctx->failure_ts = jiffies;
frostopped = readl(ctx->csr_base + RNG_ALARMSTOP);
xgene_rng_init_fro(ctx, frostopped);
/*
* We must start a timer to clear out this error
* in case the system timer wrap around
*/
xgene_rng_start_timer(ctx);
} else {
/* 2nd time failure in lesser than 1 minute? */
if (time_after(ctx->failure_ts + 60 * HZ, jiffies)) {
dev_err(ctx->dev,
"FRO shutdown failure error 0x%08X\n",
val);
} else {
/* 2nd time failure after 1 minutes, recover */
ctx->failure_ts = jiffies;
ctx->failure_cnt = 1;
/*
* We must start a timer to clear out this
* error in case the system timer wrap
* around
*/
xgene_rng_start_timer(ctx);
}
frostopped = readl(ctx->csr_base + RNG_ALARMSTOP);
xgene_rng_init_fro(ctx, frostopped);
}
}
/* Clear them all */
writel(val, ctx->csr_base + RNG_INTR_STS_ACK);
}
static irqreturn_t xgene_rng_irq_handler(int irq, void *id)
{
struct xgene_rng_dev *ctx = (struct xgene_rng_dev *) id;
/* RNG Alarm Counter overflow */
xgene_rng_chk_overflow(ctx);
return IRQ_HANDLED;
}
static int xgene_rng_data_present(struct hwrng *rng, int wait)
{
struct xgene_rng_dev *ctx = (struct xgene_rng_dev *) rng->priv;
u32 i, val = 0;
for (i = 0; i < XGENE_RNG_RETRY_COUNT; i++) {
val = readl(ctx->csr_base + RNG_INTR_STS_ACK);
if ((val & READY_MASK) || !wait)
break;
udelay(XGENE_RNG_RETRY_INTERVAL);
}
return (val & READY_MASK);
}
static int xgene_rng_data_read(struct hwrng *rng, u32 *data)
{
struct xgene_rng_dev *ctx = (struct xgene_rng_dev *) rng->priv;
int i;
for (i = 0; i < ctx->datum_size; i++)
data[i] = readl(ctx->csr_base + RNG_INOUT_0 + i * 4);
/* Clear ready bit to start next transaction */
writel(READY_MASK, ctx->csr_base + RNG_INTR_STS_ACK);
return ctx->datum_size << 2;
}
static void xgene_rng_init_internal(struct xgene_rng_dev *ctx)
{
u32 val;
writel(0x00000000, ctx->csr_base + RNG_CONTROL);
val = MAX_REFILL_CYCLES_SET(0, 10);
val = MIN_REFILL_CYCLES_SET(val, 10);
writel(val, ctx->csr_base + RNG_CONFIG);
val = ALARM_THRESHOLD_SET(0, 0xFF);
writel(val, ctx->csr_base + RNG_ALARMCNT);
xgene_rng_init_fro(ctx, 0);
writel(MONOBIT_FAIL_MASK |
POKER_FAIL_MASK |
LONG_RUN_FAIL_MASK |
RUN_FAIL_MASK |
NOISE_FAIL_MASK |
STUCK_OUT_MASK |
SHUTDOWN_OFLO_MASK |
READY_MASK, ctx->csr_base + RNG_INTR_STS_ACK);
val = ENABLE_RNG_SET(0, 1);
val = MONOBIT_FAIL_MASK_SET(val, 1);
val = POKER_FAIL_MASK_SET(val, 1);
val = LONG_RUN_FAIL_MASK_SET(val, 1);
val = RUN_FAIL_MASK_SET(val, 1);
val = NOISE_FAIL_MASK_SET(val, 1);
val = STUCK_OUT_MASK_SET(val, 1);
val = SHUTDOWN_OFLO_MASK_SET(val, 1);
writel(val, ctx->csr_base + RNG_CONTROL);
}
static int xgene_rng_init(struct hwrng *rng)
{
struct xgene_rng_dev *ctx = (struct xgene_rng_dev *) rng->priv;
ctx->failure_cnt = 0;
init_timer(&ctx->failure_timer);
ctx->revision = readl(ctx->csr_base + RNG_EIP_REV);
dev_dbg(ctx->dev, "Rev %d.%d.%d\n",
MAJOR_HW_REV_RD(ctx->revision),
MINOR_HW_REV_RD(ctx->revision),
HW_PATCH_LEVEL_RD(ctx->revision));
dev_dbg(ctx->dev, "Options 0x%08X",
readl(ctx->csr_base + RNG_OPTIONS));
xgene_rng_init_internal(ctx);
ctx->datum_size = RNG_MAX_DATUM;
return 0;
}
#ifdef CONFIG_ACPI
static const struct acpi_device_id xgene_rng_acpi_match[] = {
{ "APMC0D18", },
{ }
};
MODULE_DEVICE_TABLE(acpi, xgene_rng_acpi_match);
#endif
static struct hwrng xgene_rng_func = {
.name = "xgene-rng",
.init = xgene_rng_init,
.data_present = xgene_rng_data_present,
.data_read = xgene_rng_data_read,
};
static int xgene_rng_probe(struct platform_device *pdev)
{
struct resource *res;
struct xgene_rng_dev *ctx;
int rc = 0;
ctx = devm_kzalloc(&pdev->dev, sizeof(*ctx), GFP_KERNEL);
if (!ctx)
return -ENOMEM;
ctx->dev = &pdev->dev;
platform_set_drvdata(pdev, ctx);
res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
ctx->csr_base = devm_ioremap_resource(&pdev->dev, res);
if (IS_ERR(ctx->csr_base))
return PTR_ERR(ctx->csr_base);
ctx->irq = platform_get_irq(pdev, 0);
if (ctx->irq < 0) {
dev_err(&pdev->dev, "No IRQ resource\n");
return ctx->irq;
}
dev_dbg(&pdev->dev, "APM X-Gene RNG BASE %p ALARM IRQ %d",
ctx->csr_base, ctx->irq);
rc = devm_request_irq(&pdev->dev, ctx->irq, xgene_rng_irq_handler, 0,
dev_name(&pdev->dev), ctx);
if (rc) {
dev_err(&pdev->dev, "Could not request RNG alarm IRQ\n");
return rc;
}
/* Enable IP clock */
ctx->clk = devm_clk_get(&pdev->dev, NULL);
if (IS_ERR(ctx->clk)) {
dev_warn(&pdev->dev, "Couldn't get the clock for RNG\n");
} else {
rc = clk_prepare_enable(ctx->clk);
if (rc) {
dev_warn(&pdev->dev,
"clock prepare enable failed for RNG");
return rc;
}
}
xgene_rng_func.priv = (unsigned long) ctx;
rc = hwrng_register(&xgene_rng_func);
if (rc) {
dev_err(&pdev->dev, "RNG registering failed error %d\n", rc);
if (!IS_ERR(ctx->clk))
clk_disable_unprepare(ctx->clk);
return rc;
}
rc = device_init_wakeup(&pdev->dev, 1);
if (rc) {
dev_err(&pdev->dev, "RNG device_init_wakeup failed error %d\n",
rc);
if (!IS_ERR(ctx->clk))
clk_disable_unprepare(ctx->clk);
hwrng_unregister(&xgene_rng_func);
return rc;
}
return 0;
}
static int xgene_rng_remove(struct platform_device *pdev)
{
struct xgene_rng_dev *ctx = platform_get_drvdata(pdev);
int rc;
rc = device_init_wakeup(&pdev->dev, 0);
if (rc)
dev_err(&pdev->dev, "RNG init wakeup failed error %d\n", rc);
if (!IS_ERR(ctx->clk))
clk_disable_unprepare(ctx->clk);
hwrng_unregister(&xgene_rng_func);
return rc;
}
static const struct of_device_id xgene_rng_of_match[] = {
{ .compatible = "apm,xgene-rng" },
{ }
};
MODULE_DEVICE_TABLE(of, xgene_rng_of_match);
static struct platform_driver xgene_rng_driver = {
.probe = xgene_rng_probe,
.remove = xgene_rng_remove,
.driver = {
.name = "xgene-rng",
.of_match_table = xgene_rng_of_match,
.acpi_match_table = ACPI_PTR(xgene_rng_acpi_match),
},
};
module_platform_driver(xgene_rng_driver);
MODULE_DESCRIPTION("APM X-Gene RNG driver");
MODULE_LICENSE("GPL");
