Add pico_unique_id to inject ID access before main and provide accessor

This commit is contained in:
Luke Wren 2021-01-26 15:09:26 +00:00 committed by Graham Sanderson
parent bb3cf10a09
commit c1196e9af6
4 changed files with 92 additions and 0 deletions

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@ -37,6 +37,7 @@ if (NOT PICO_BARE_METAL)
pico_add_subdirectory(boot_stage2)
pico_add_subdirectory(pico_multicore)
pico_add_subdirectory(pico_unique_id)
pico_add_subdirectory(pico_bit_ops)
pico_add_subdirectory(pico_divider)

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@ -0,0 +1,9 @@
add_library(pico_unique_id INTERFACE)
target_sources(pico_unique_id INTERFACE
${CMAKE_CURRENT_LIST_DIR}/unique_id.c
)
target_include_directories(pico_unique_id INTERFACE ${CMAKE_CURRENT_LIST_DIR}/include)
target_link_libraries(pico_unique_id INTERFACE hardware_flash)

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@ -0,0 +1,53 @@
/*
* Copyright (c) 2021 Raspberry Pi (Trading) Ltd.
*
* SPDX-License-Identifier: BSD-3-Clause
*/
#ifndef _PICO_UNIQUE_ID_H_
#define _PICO_UNIQUE_ID_H_
#ifdef __cplusplus
extern "C" {
#endif
/** \file pico/unique_id.h
* \defgroup unique_id unique_id
*
* Unique device ID access API
*
* RP2040 does not have an on-board unique identifier (all instances of RP2040
* silicon are identical and have no persistent state). However, RP2040 boots
* from serial NOR flash devices which have a 64-bit unique ID as a standard
* feature, and there is a 1:1 association between RP2040 and flash, so this
* is suitable for use as a unique identifier for an RP2040-based board.
*
* This library injects a call to the flash_get_unique_id function from the
* hardware_flash library, to run before main, and stores the result in a
* static location which can safely be accessed at any time via
* pico_get_unique_id().
*
* This avoids some pitfalls of the hardware_flash API, which requires any
* flash-resident interrupt routines to be disabled when called into.
*/
#define PICO_UNIQUE_ID_SIZE_BYTES 8
/*! \brief Get unique ID
* \ingroup unique_id
*
* Get the unique 64-bit device identifier which was retrieved from the
* external NOR flash device at boot.
*
* On PICO_NO_FLASH builds the unique identifier is set to all 0xEE.
*
* \param id_out an 8-byte buffer to which the identifer will be written.
*/
void pico_get_unique_id(uint8_t *id_out);
#ifdef __cplusplus
}
#endif
#endif

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@ -0,0 +1,29 @@
/*
* Copyright (c) 2020 Raspberry Pi (Trading) Ltd.
*
* SPDX-License-Identifier: BSD-3-Clause
*/
#include "hardware/flash.h"
#include "pico/unique_id.h"
static_assert(PICO_UNIQUE_ID_SIZE_BYTES == FLASH_UNIQUE_ID_SIZE_BYTES);
static uint8_t retrieved_id[PICO_UNIQUE_ID_SIZE_BYTES];
static void __attribute__((constructor)) _retrieve_unique_id_on_boot() {
#if PICO_NO_FLASH
// The hardware_flash call will panic() if called directly on a NO_FLASH
// build. Since this constructor is pre-main it would be annoying to
// debug, so just produce something well-defined and obviously wrong.
for (int i = 0; i < PICO_UNIQUE_ID_SIZE_BYTES; i++)
retrieved_id[i] = 0xee;
#else
flash_get_unique_id(retrieved_id);
#endif
}
void pico_get_unique_id(uint8_t *id_out) {
for (int i = 0; i < PICO_UNIQUE_ID_SIZE_BYTES; i++)
id_out[i] = retrieved_id[i];
}