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- .. SPDX-License-Identifier: GPL-2.0
- ===============================
- TI EMIF SDRAM Controller Driver
- ===============================
- Author
- ======
- Aneesh V <[email protected]>
- Location
- ========
- driver/memory/emif.c
- Supported SoCs:
- ===============
- TI OMAP44xx
- TI OMAP54xx
- Menuconfig option:
- ==================
- Device Drivers
- Memory devices
- Texas Instruments EMIF driver
- Description
- ===========
- This driver is for the EMIF module available in Texas Instruments
- SoCs. EMIF is an SDRAM controller that, based on its revision,
- supports one or more of DDR2, DDR3, and LPDDR2 SDRAM protocols.
- This driver takes care of only LPDDR2 memories presently. The
- functions of the driver includes re-configuring AC timing
- parameters and other settings during frequency, voltage and
- temperature changes
- Platform Data (see include/linux/platform_data/emif_plat.h)
- ===========================================================
- DDR device details and other board dependent and SoC dependent
- information can be passed through platform data (struct emif_platform_data)
- - DDR device details: 'struct ddr_device_info'
- - Device AC timings: 'struct lpddr2_timings' and 'struct lpddr2_min_tck'
- - Custom configurations: customizable policy options through
- 'struct emif_custom_configs'
- - IP revision
- - PHY type
- Interface to the external world
- ===============================
- EMIF driver registers notifiers for voltage and frequency changes
- affecting EMIF and takes appropriate actions when these are invoked.
- - freq_pre_notify_handling()
- - freq_post_notify_handling()
- - volt_notify_handling()
- Debugfs
- =======
- The driver creates two debugfs entries per device.
- - regcache_dump : dump of register values calculated and saved for all
- frequencies used so far.
- - mr4 : last polled value of MR4 register in the LPDDR2 device. MR4
- indicates the current temperature level of the device.
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