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1.. SPDX-License-Identifier: GPL-2.02 3===============================4TI EMIF SDRAM Controller Driver5===============================6 7Author8======9Aneesh V <aneesh@ti.com>10 11Location12========13driver/memory/emif.c14 15Supported SoCs:16===============17TI OMAP44xx18TI OMAP54xx19 20Menuconfig option:21==================22Device Drivers23 Memory devices24 Texas Instruments EMIF driver25 26Description27===========28This driver is for the EMIF module available in Texas Instruments29SoCs. EMIF is an SDRAM controller that, based on its revision,30supports one or more of DDR2, DDR3, and LPDDR2 SDRAM protocols.31This driver takes care of only LPDDR2 memories presently. The32functions of the driver includes re-configuring AC timing33parameters and other settings during frequency, voltage and34temperature changes35 36Platform Data (see include/linux/platform_data/emif_plat.h)37===========================================================38DDR device details and other board dependent and SoC dependent39information can be passed through platform data (struct emif_platform_data)40 41- DDR device details: 'struct ddr_device_info'42- Device AC timings: 'struct lpddr2_timings' and 'struct lpddr2_min_tck'43- Custom configurations: customizable policy options through44 'struct emif_custom_configs'45- IP revision46- PHY type47 48Interface to the external world49===============================50EMIF driver registers notifiers for voltage and frequency changes51affecting EMIF and takes appropriate actions when these are invoked.52 53- freq_pre_notify_handling()54- freq_post_notify_handling()55- volt_notify_handling()56 57Debugfs58=======59The driver creates two debugfs entries per device.60 61- regcache_dump : dump of register values calculated and saved for all62 frequencies used so far.63- mr4 : last polled value of MR4 register in the LPDDR2 device. MR464 indicates the current temperature level of the device.65