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authorAneesh V <aneesh@ti.com>2012-04-27 17:54:05 +0530
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2012-05-02 00:10:49 -0700
commit7ec944538dde3d7f490bd4d2619051789db5c3c3 (patch)
tree03bbd82691ce1d620a14d31e8bc3f231232e660d /Documentation/memory-devices
parent6c8b0906cf447adf2aeeed3d79eb5cec7f362d1f (diff)
memory: emif: add basic infrastructure for EMIF driver
EMIF is an SDRAM controller used in various Texas Instruments SoCs. EMIF supports, based on its revision, one or more of LPDDR2/DDR2/DDR3 protocols. Add the basic infrastructure for EMIF driver that includes driver registration, probe, parsing of platform data etc. Signed-off-by: Aneesh V <aneesh@ti.com> Reviewed-by: Santosh Shilimkar <santosh.shilimkar@ti.com> Reviewed-by: Benoit Cousson <b-cousson@ti.com> [santosh.shilimkar@ti.com: Moved to drivers/memory from drivers/misc] Signed-off-by: Santosh Shilimkar <santosh.shilimkar@ti.com> Tested-by: Lokesh Vutla <lokeshvutla@ti.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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+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.

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