From 0b7cbfb5e1f03f58241bf236cca303ee45e14b4f Mon Sep 17 00:00:00 2001 From: Paul Walmsley Date: Wed, 25 Jun 2008 18:09:37 -0600 Subject: [ARM] OMAP3 pwrdm: add hardware save-and-restore (SAR) support MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit 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 for reviewing an earlier version of these patches, and Richard Woodruff 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 Signed-off-by: Tony Lindgren Signed-off-by: Russell King --- arch/arm/mach-omap2/powerdomain.c | 68 +++++++++++++++++++++++++++++++++++++++ 1 file changed, 68 insertions(+) (limited to 'arch/arm/mach-omap2') diff --git a/arch/arm/mach-omap2/powerdomain.c b/arch/arm/mach-omap2/powerdomain.c index 9a803492b28..73e2971b175 100644 --- a/arch/arm/mach-omap2/powerdomain.c +++ b/arch/arm/mach-omap2/powerdomain.c @@ -1002,6 +1002,74 @@ int pwrdm_clear_all_prev_pwrst(struct powerdomain *pwrdm) return 0; } +/** + * pwrdm_enable_hdwr_sar - enable automatic hardware SAR for a pwrdm + * @pwrdm: struct powerdomain * + * + * Enable automatic context save-and-restore upon power state change + * for some devices in a powerdomain. Warning: this only affects a + * subset of devices in a powerdomain; check the TRM closely. Returns + * -EINVAL if the powerdomain pointer is null or if the powerdomain + * does not support automatic save-and-restore, or returns 0 upon + * success. + */ +int pwrdm_enable_hdwr_sar(struct powerdomain *pwrdm) +{ + if (!pwrdm) + return -EINVAL; + + if (!(pwrdm->flags & PWRDM_HAS_HDWR_SAR)) + return -EINVAL; + + pr_debug("powerdomain: %s: setting SAVEANDRESTORE bit\n", + pwrdm->name); + + prm_rmw_mod_reg_bits(0, 1 << OMAP3430ES2_SAVEANDRESTORE_SHIFT, + pwrdm->prcm_offs, PM_PWSTCTRL); + + return 0; +} + +/** + * pwrdm_disable_hdwr_sar - disable automatic hardware SAR for a pwrdm + * @pwrdm: struct powerdomain * + * + * Disable automatic context save-and-restore upon power state change + * for some devices in a powerdomain. Warning: this only affects a + * subset of devices in a powerdomain; check the TRM closely. Returns + * -EINVAL if the powerdomain pointer is null or if the powerdomain + * does not support automatic save-and-restore, or returns 0 upon + * success. + */ +int pwrdm_disable_hdwr_sar(struct powerdomain *pwrdm) +{ + if (!pwrdm) + return -EINVAL; + + if (!(pwrdm->flags & PWRDM_HAS_HDWR_SAR)) + return -EINVAL; + + pr_debug("powerdomain: %s: clearing SAVEANDRESTORE bit\n", + pwrdm->name); + + prm_rmw_mod_reg_bits(1 << OMAP3430ES2_SAVEANDRESTORE_SHIFT, 0, + pwrdm->prcm_offs, PM_PWSTCTRL); + + return 0; +} + +/** + * pwrdm_has_hdwr_sar - test whether powerdomain supports hardware SAR + * @pwrdm: struct powerdomain * + * + * Returns 1 if powerdomain 'pwrdm' supports hardware save-and-restore + * for some devices, or 0 if it does not. + */ +bool pwrdm_has_hdwr_sar(struct powerdomain *pwrdm) +{ + return (pwrdm && pwrdm->flags & PWRDM_HAS_HDWR_SAR) ? 1 : 0; +} + /** * pwrdm_wait_transition - wait for powerdomain power transition to finish * @pwrdm: struct powerdomain * to wait for -- cgit v1.2.3