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1 | TI EMIF SDRAM Controller Driver: | ||
2 | |||
3 | Author | ||
4 | ======== | ||
5 | Aneesh V <aneesh@ti.com> | ||
6 | |||
7 | Location | ||
8 | ============ | ||
9 | driver/memory/emif.c | ||
10 | |||
11 | Supported SoCs: | ||
12 | =================== | ||
13 | TI OMAP44xx | ||
14 | TI OMAP54xx | ||
15 | |||
16 | Menuconfig option: | ||
17 | ========================== | ||
18 | Device Drivers | ||
19 | Memory devices | ||
20 | Texas Instruments EMIF driver | ||
21 | |||
22 | Description | ||
23 | =========== | ||
24 | This driver is for the EMIF module available in Texas Instruments | ||
25 | SoCs. EMIF is an SDRAM controller that, based on its revision, | ||
26 | supports one or more of DDR2, DDR3, and LPDDR2 SDRAM protocols. | ||
27 | This driver takes care of only LPDDR2 memories presently. The | ||
28 | functions of the driver includes re-configuring AC timing | ||
29 | parameters and other settings during frequency, voltage and | ||
30 | temperature changes | ||
31 | |||
32 | Platform Data (see include/linux/platform_data/emif_plat.h): | ||
33 | ===================================================================== | ||
34 | DDR device details and other board dependent and SoC dependent | ||
35 | information can be passed through platform data (struct emif_platform_data) | ||
36 | - DDR device details: 'struct ddr_device_info' | ||
37 | - Device AC timings: 'struct lpddr2_timings' and 'struct lpddr2_min_tck' | ||
38 | - Custom configurations: customizable policy options through | ||
39 | 'struct emif_custom_configs' | ||
40 | - IP revision | ||
41 | - PHY type | ||
42 | |||
43 | Interface to the external world: | ||
44 | ================================ | ||
45 | EMIF driver registers notifiers for voltage and frequency changes | ||
46 | affecting EMIF and takes appropriate actions when these are invoked. | ||
47 | - freq_pre_notify_handling() | ||
48 | - freq_post_notify_handling() | ||
49 | - volt_notify_handling() | ||
50 | |||
51 | Debugfs | ||
52 | ======== | ||
53 | The driver creates two debugfs entries per device. | ||
54 | - regcache_dump : dump of register values calculated and saved for all | ||
55 | frequencies used so far. | ||
56 | - mr4 : last polled value of MR4 register in the LPDDR2 device. MR4 | ||
57 | indicates the current temperature level of the device. | ||