Posts on Maquefel's Stash

Don’t fear the bricking (unbricking Unmatched via JTAG)

Tue, 11 Jan 2022 07:41:50 +0000

First published at: https://forums.sifive.com/t/dont-fear-the-bricking-unbricking-unmatched-via-jtag/5449

Despite, as i think, this is quite obvious, some people miss the point.

So let me show you how to unbrick the HiFive Unmatched board, that’s usefull in case of:

installing BSP without the need of preparing the SD card in advance (you still have to insert it through)
unbricking the board in case of deleting U-Boot
testing U-Boot + OpenSBI on fly hijacking the load addresses

The scheme works independently of selected MSEL value.

Using gpio-generic and irq_chip_generic subsystems for gpio driver

Sat, 10 Sep 2016 12:31:52 +0000

Intoduction

This article is a logical continuation of the previous one and it is recommended to stady after reading the previous material. The current note is necessary for understanding the subsequent material, a further understanding gpio subsystem as a whole and helps with the development of own gpio drivers. The provisions of this article have not only apply to our virtual driver gpio, but also to any mmio gpio driver in general. It will focus on “optimizing” referred to in the preceding article.

QEMU ivshmem Introducing interrupt capable virtual gpio concept

Thu, 14 Jul 2016 12:21:27 +0000

Introduction

It’s hard to underestimate the role of GPIO’s, especially in ARM embedded systems. Apart of being a very popular material for starters, GPIO’s provide a way for controlling the many peripheral devices, act as source of valuable interrupts, or even can be the only way to communicate the world for a SOC.