[ARM] OMAP3 pwrdm: add hardware save-and-restore (SAR) support
OMAP3430ES2+ introduces a new feature: optional powerdomain context
hardware save-and-restore (SAR). Currently, this feature only applies
to USBHOST and USBTLL module context when the USBHOST or CORE
powerdomains enter a low-power sleep state[1]. This feature avoids
re-enumeration of USB devices when the powerdomains return from idle,
which is potentially time-consuming.
This patch adds support for enabling and disabling hardware
save-and-restore to the powerdomain code. Three new functions are
added, pwrdm_enable_hdwr_sar(), pwrdm_disable_hdwr_sar(), and
pwrdm_can_hdwr_sar(). A new struct powerdomain "flags" field is
added, with a PWRDM_HAS_HDWR_SAR flag to indicate powerdomains with
SAR support.
Thanks to Jouni Högander <jouni.hogander@nokia.com> for reviewing an
earlier version of these patches, and Richard Woodruff <r-woodruff2@ti.com>
for clarifying the purpose of these bits.
1. For the USBHOST controller module, context loss occurs when the
USBHOST powerdomain enters off-idle. For USBTLL, context loss
occurs either if CORE enters off-idle, or if the CORE logic is
configured to turn off when CORE enters retention-idle (OSWR).
34xx ES2 TRM 4.8.6.1.1, 4.8.6.1.2
Signed-off-by: Paul Walmsley <paul@pwsan.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2 files changed