From: Paul Walmsley <paul@pwsan.com>
Date: Thu, 26 Jun 2008 00:09:37 +0000 (-0600)
Subject: [ARM] OMAP3 pwrdm: add hardware save-and-restore (SAR) support
X-Git-Tag: v2.6.28-rc1~293^2~2^2~11^2~1
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=0b7cbfb5e1f03f58241bf236cca303ee45e14b4f;p=pandora-kernel.git

[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>
---

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