[PATCH v3 0/4] AM437x: Add rtc-only + DDR mode support

From: Keerthy <j-keerthy@ti.com>
To: <tony@atomide.com>, <alexandre.belloni@bootlin.com>,
	<a.zummo@towertech.it>, <t-kristo@ti.com>
Cc: <ssantosh@kernel.org>, <d-gerlach@ti.com>,
	<linux-omap@vger.kernel.org>,
	<linux-arm-kernel@lists.infradead.org>,
	<linux-rtc@vger.kernel.org>, <j-keerthy@ti.com>
Subject: [PATCH v3 0/4] AM437x: Add rtc-only + DDR mode support
Date: Wed, 3 Apr 2019 10:27:38 +0530	[thread overview]
Message-ID: <20190403045742.2243-1-j-keerthy@ti.com> (raw)

RTC plus DDR in self-refresh is a power saving mode where in the entire
system including the different voltage rails from PMIC are shutdown except
the ones feeding on to RTC and DDR. DDR is kept in self-refresh hence the
contents are preserved.

RTC ALARM2 is connected to PMIC_EN line. TPS65218 PMIC has granular voltage rail
control. The voltage rail feeding RTC is kept on while the rest of the PMIC
regulators are powered off.

Once the ALARM2 is triggered we enter the mode with DDR in self-refresh
and RTC Ticking. After a predetermined time an RTC ALARM1 triggers
waking up the system. The control goes to bootloader. The bootloader then checks
RTC scratchpad registers to confirm it was an rtc_only wakeup and follows
a different path, configure bare minimal clocks for ddr and then jumps to
the resume address in another RTC scratchpad registers and transfers the
control to Kernel. Kernel then restores the saved context.

The patch series adds rtc-only + DDR mode support am am437x
Tested DS0, rtc+ddr back and forth on am437x-gp-evm board.

This mode works only with u-boot built with am43xx_evm_rtconly_defconfig

Additional patch is needed for omap-gpio save restore which will
come as fixes later.

Hardware Description of this mode can be found here: 

http://www.ti.com/lit/ug/spruhl7h/spruhl7h.pdf Page 2884.

Changes in v3:

  * Exported out omap_rtc_poweroff_program function & removed
    the patch to add a generic rtc interface as it is specific
    to am43 at the moment.

Keerthy (4):
  rtc: OMAP: Add support for rtc-only mode
  arm: mach-omap2: pm33xx: Add support for rtc+ddr in self  refresh mode
  soc: ti: pm33xx: Push the am33xx_push_sram_idle to the top
  soc: ti: pm33xx: AM437X: Add rtc_only with ddr in self-refresh support

 arch/arm/mach-omap2/pm33xx-core.c    |  76 +++++++-
 drivers/rtc/rtc-omap.c               |  49 ++++-
 drivers/soc/ti/Kconfig               |   5 +-
 drivers/soc/ti/pm33xx.c              | 273 ++++++++++++++++++++++-----
 include/linux/platform_data/pm33xx.h |   5 +
 include/linux/rtc/rtc-omap.h         |   7 +
 6 files changed, 354 insertions(+), 61 deletions(-)
 create mode 100644 include/linux/rtc/rtc-omap.h

-- 
2.17.1