1.. SPDX-License-Identifier: GPL-2.0 2 3=============================== 4TI EMIF SDRAM Controller Driver 5=============================== 6 7Author 8====== 9Aneesh V <aneesh@ti.com> 10 11Location 12======== 13driver/memory/emif.c 14 15Supported SoCs: 16=============== 17TI OMAP44xx 18TI OMAP54xx 19 20Menuconfig option: 21================== 22Device Drivers 23 Memory devices 24 Texas Instruments EMIF driver 25 26Description 27=========== 28This driver is for the EMIF module available in Texas Instruments 29SoCs. 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. The 32functions of the driver includes re-configuring AC timing 33parameters and other settings during frequency, voltage and 34temperature changes 35 36Platform Data (see include/linux/platform_data/emif_plat.h) 37=========================================================== 38DDR device details and other board dependent and SoC dependent 39information 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 through 44 'struct emif_custom_configs' 45- IP revision 46- PHY type 47 48Interface to the external world 49=============================== 50EMIF driver registers notifiers for voltage and frequency changes 51affecting 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 57Debugfs 58======= 59The driver creates two debugfs entries per device. 60 61- regcache_dump : dump of register values calculated and saved for all 62 frequencies used so far. 63- mr4 : last polled value of MR4 register in the LPDDR2 device. MR4 64 indicates the current temperature level of the device. 65