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diff --git a/Documentation/driver-api/memory-devices/ti-emif.rst b/Documentation/driver-api/memory-devices/ti-emif.rst new file mode 100644 index 000000000000..dea2ad9bcd7e --- /dev/null +++ b/Documentation/driver-api/memory-devices/ti-emif.rst @@ -0,0 +1,64 @@ +.. SPDX-License-Identifier: GPL-2.0 + +=============================== +TI EMIF SDRAM Controller Driver +=============================== + +Author +====== +Aneesh V <aneesh@ti.com> + +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. |