|author||Michal Meloun <mmel@FreeBSD.org>||2020-09-19 11:06:41 +0000|
|committer||Michal Meloun <mmel@FreeBSD.org>||2020-09-19 11:06:41 +0000|
Add NetBSD compatible bus_space_peek_N() and bus_space_poke_N() functions.
One problem with the bus_space_read_N() and bus_space_write_N() family of functions is that they provide no protection against exceptions which can occur when no physical hardware or device responds to the read or write cycles. In such a situation, the system typically would panic due to a kernel-mode bus error. The bus_space_peek_N() and bus_space_poke_N() family of functions provide a mechanism to handle these exceptions gracefully without the risk of crashing the system. Typical example is access to PCI(e) configuration space in bus enumeration function on badly implemented PCI(e) root complexes (RK3399 or Neoverse N1 N1SDP and/or access to PCI(e) register when device is in deep sleep state. This commit adds a real implementation for arm64 only. The remaining architectures have bus_space_peek()/bus_space_poke() emulated by using bus_space_read()/bus_space_write() (without exception handling). MFC after: 1 month Reviewed by: kib Differential Revision: https://reviews.freebsd.org/D25371
Notes: svn path=/head/; revision=365899
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