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drivers: entropy: add Atmel SAM entropy generator driver

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Tested on the Atmel SAM E70 Xplained board.

Signed-off-by: Aurelien Jarno <aurelien@aurel32.net>
This commit is contained in:
Aurelien Jarno 2018-11-04 00:13:01 +01:00 • committed by Anas Nashif
commit 16994088fd
8 changed files with 177 additions and 0 deletions
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1
drivers/entropy/CMakeLists.txt
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@ -4,6 +4,7 @@ zephyr_library_sources_ifdef(CONFIG_ENTROPY_ESP32_RNG entropy_esp32.c)
zephyr_library_sources_ifdef(CONFIG_ENTROPY_MCUX_RNGA entropy_mcux_rnga.c)
zephyr_library_sources_ifdef(CONFIG_ENTROPY_MCUX_TRNG entropy_mcux_trng.c)
zephyr_library_sources_ifdef(CONFIG_ENTROPY_NRF5_RNG entropy_nrf5.c)
zephyr_library_sources_ifdef(CONFIG_ENTROPY_SAM_RNG entropy_sam.c)
zephyr_library_sources_ifdef(CONFIG_ENTROPY_STM32_RNG entropy_stm32.c)
zephyr_library_sources_ifdef(CONFIG_FAKE_ENTROPY_NATIVE_POSIX fake_entropy_native_posix.c)
zephyr_library_sources_ifdef(CONFIG_USERSPACE entropy_handlers.c)

1
drivers/entropy/Kconfig
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@ -17,6 +17,7 @@ source "drivers/entropy/Kconfig.mcux"
source "drivers/entropy/Kconfig.stm32"
source "drivers/entropy/Kconfig.esp32"
source "drivers/entropy/Kconfig.nrf5"
source "drivers/entropy/Kconfig.sam"
source "drivers/entropy/Kconfig.native_posix"
config ENTROPY_HAS_DRIVER

14
drivers/entropy/Kconfig.sam Normal file
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@ -0,0 +1,14 @@
# Kconfig.sam - Atmel SAM TRNG configuration
#
# Copyright (c) 2018 Aurelien Jarno
#
# SPDX-License-Identifier: Apache-2.0
menuconfig ENTROPY_SAM_RNG
bool "Atmel SAM MCU Family True Random Number Generator (TRNG) Driver"
depends on SOC_FAMILY_SAM
depends on ENTROPY_GENERATOR
select ENTROPY_HAS_DRIVER
select HAS_DTS_ENTROPY
help
Enable True Random Number Generator (TRNG) driver for Atmel SAM MCUs.

95
drivers/entropy/entropy_sam.c Normal file
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@ -0,0 +1,95 @@
/*
* Copyright (c) 2018 Aurelien Jarno
*
* SPDX-License-Identifier: Apache-2.0
*/
#include <device.h>
#include <entropy.h>
#include <errno.h>
#include <init.h>
#include <soc.h>
#include <string.h>
struct trng_sam_dev_cfg {
Trng *regs;
};
#define DEV_CFG(dev) \
((const struct trng_sam_dev_cfg *const)(dev)->config->config_info)
static int entropy_sam_wait_ready(Trng *const trng)
{
/* According to the reference manual, the generator provides
* one 32-bit random value every 84 peripheral clock cycles.
* MCK may not be smaller than HCLK/4, so it should not take
* more than 336 HCLK ticks. Assuming the CPU can do 1
* instruction per HCLK the number of times to loop before
* the TRNG is ready is less than 1000. And that is when
* assuming the loop only takes 1 instruction. So looping a
* million times should be more than enough.
*/
int timeout = 1000000;
while (!(trng->TRNG_ISR & TRNG_ISR_DATRDY)) {
if (timeout-- == 0) {
return -ETIMEDOUT;
}
k_yield();
}
return 0;
}
static int entropy_sam_get_entropy(struct device *dev, u8_t *buffer,
u16_t length)
{
Trng *const trng = DEV_CFG(dev)->regs;
while (length > 0) {
size_t to_copy;
u32_t value;
int res;
res = entropy_sam_wait_ready(trng);
if (res < 0) {
return res;
}
value = trng->TRNG_ODATA;
to_copy = min(length, sizeof(value));
memcpy(buffer, &value, to_copy);
buffer += to_copy;
length -= to_copy;
}
return 0;
}
static int entropy_sam_init(struct device *dev)
{
Trng *const trng = DEV_CFG(dev)->regs;
/* Enable the user interface clock */
soc_pmc_peripheral_enable(DT_ENTROPY_SAM_TRNG_PERIPHERAL_ID);
/* Enable the TRNG */
trng->TRNG_CR = TRNG_CR_KEY_PASSWD | TRNG_CR_ENABLE;
return 0;
}
static const struct entropy_driver_api entropy_sam_api = {
.get_entropy = entropy_sam_get_entropy
};
static const struct trng_sam_dev_cfg trng_sam_cfg = {
.regs = (Trng *)DT_ENTROPY_SAM_TRNG_BASE_ADDRESS,
};
DEVICE_AND_API_INIT(entropy_sam, CONFIG_ENTROPY_NAME,
entropy_sam_init, NULL, &trng_sam_cfg,
PRE_KERNEL_1, CONFIG_KERNEL_INIT_PRIORITY_DEVICE,
&entropy_sam_api);

9
dts/arm/atmel/same70.dtsi
View file

@ -252,6 +252,15 @@
status = "disabled";
label = "USBHS";
};
trng: random@40070000 {
compatible = "atmel,sam-trng";
reg = <0x40070000 0x4000>;
interrupts = <57 0>;
peripheral-id = <57>;
status = "ok";
label = "TRNG";
};
};
};

45
dts/bindings/rng/atmel,sam-trng.yaml Normal file
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@ -0,0 +1,45 @@
#
# Copyright (c) 2018, Aurelien Jarno
#
# SPDX-License-Identifier: Apache-2.0
#
---
title: Atmel SAM TRNG (True Random Number Generator)
version: 0.1
description: >
This binding gives a base representation of the Atmel SAM RNG
properties:
compatible:
type: string
category: required
description: compatible strings
constraint: "atmel,sam-trng"
generation: define
reg:
type: int
description: mmio register space
generation: define
category: required
interrupts:
type: compound
category: required
description: required interrupts
generation: define
peripheral-id:
type: int
description: peripheral ID
generation: define
category: required
label:
type: string
category: required
description: Human readable string describing the device (used by Zephyr for API name)
generation: define
...

5
soc/arm/atmel_sam/same70/Kconfig.defconfig.series
View file

@ -73,4 +73,9 @@ config USB_DC_SAM
default y
endif # USB
if ENTROPY_GENERATOR
config ENTROPY_SAM_RNG
default y
endif # ENTROPY_GENERATOR
endif # SOC_SERIES_SAME70

7
soc/arm/atmel_sam/same70/dts_fixup.h
View file

@ -128,4 +128,11 @@
#define DT_USBHS_PERIPHERAL_ID DT_ATMEL_SAM_USBHS_40038000_PERIPHERAL_ID
#define DT_USBHS_RAM_BASE_ADDRESS DT_ATMEL_SAM_USBHS_40038000_RAM_0
#define DT_ENTROPY_SAM_TRNG_BASE_ADDRESS DT_ATMEL_SAM_TRNG_40070000_BASE_ADDRESS
#define DT_ENTROPY_SAM_TRNG_IRQ DT_ATMEL_SAM_TRNG_40070000_IRQ_0
#define DT_ENTROPY_SAM_TRNG_IRQ_PRI DT_ATMEL_SAM_TRNG_40070000_IRQ_0_PRIORITY
#define DT_ENTROPY_SAM_TRNG_PERIPHERAL_ID DT_ATMEL_SAM_TRNG_40070000_PERIPHERAL_ID
#define DT_ENTROPY_SAM_TRNG_NAME DT_ATMEL_SAM_TRNG_40070000_LABEL
#define CONFIG_ENTROPY_NAME DT_ATMEL_SAM_TRNG_40070000_LABEL
/* End of SoC Level DTS fixup file */