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