Kyungmin Park<kmpark@xxxxxxxxxxxxx> 2012-03-17 15:10 (GMT+09:00) > Hi, > On 3/17/12, Aneesh V wrote: > > Add a driver for the EMIF SDRAM controller used in TI SoCs > > > > EMIF is an SDRAM controller that supports, based on its revision, > > one or more of LPDDR2/DDR2/DDR3 protocols.This driver adds support > > for LPDDR2. > > > > The driver supports the following features: > > - Calculates the DDR AC timing parameters to be set in EMIF > > registers using data from the device data-sheets and based > > on the DDR frequency. If data from data-sheets is not available > > default timing values from the JEDEC spec are used. These > > will be safe, but not necessarily optimal > > - API for changing timings during DVFS or at boot-up This means that you alreeady have callbacks to create a devfreq device driver that supports DVFS on the device. This doesn't need to be a misc device driver then. > > - Temperature alert configuration and handling of temperature > > alerts, if any for LPDDR2 devices > > * temperature alert is based on periodic polling of MR4 mode > > register in DDR devices automatically performed by hardware > > * timings are de-rated and brought back to nominal when > > temperature raises and falls respectively This can be a feature overriding "max_freq" inside the Omap EMIF devfreq device driver though it maybe (or not.. I just don't sure) be better to use thermal framework as well. Cheers! MyungJoo > > - Cache of calculated register values to avoid re-calculating > > them > > > > The driver will need some minor updates when it is eventually > > integrated with Dynamic Voltage and Frequency Scaling (DVFS). > > This can not be done now as DVFS support is not available in > > the mainline yet. > Do you see the devfreq? it's designed for non-cpu device frequency. > It's role is similar with cpufreq. > > Now samsung exynos uses devfreq for DRAM bus frequency. > > Thank you, > Kyungmin Park > > > > Discussions with Santosh Shilimkar > > were immensely helpful in shaping up the interfaces. Vibhore Vardhan > > did the initial code snippet for thermal > > handling. > > > > Testing: > > - The driver is tested on OMAP4430 SDP. > > - The driver in a slightly adapted form is also tested on OMAP5. > > - Since mainline kernel doesn't have DVFS support yet, > > testing was done using a test module. > > - Temperature alert handling was tested with simulated interrupts > > and faked temperature values as testing all cases in real-life > > scenarios is difficult. > > - Tested the driver as a module > > > > Cc: Greg KH > > > > v4: > > - Converted instances of EXPORT_SYMBOL to EXPORT_SYMBOL_GPL > > - Removed un-necessary "#ifndef __ASSEMBLY__' > > - Minor formatting fix > > > > v2: > > - Fixed a bug found in the implementation of errata i728 > > workaround > > - Fixed the value of frequency printed in debugfs > > - Dropped the hwmod patch as Paul has already posted a > > a hwmod series [1] that adds hwmod for EMIF > > - Converted instances of __init to __init_or_module > > > > [1] http://thread.gmane.org/gmane.linux.ports.arm.omap/72855 > > > > Aneesh V (7): > > misc: ddr: add LPDDR2 data from JESD209-2 > > misc: emif: add register definitions for EMIF > > misc: emif: add basic infrastructure for EMIF driver > > misc: emif: handle frequency and voltage change events > > misc: emif: add interrupt and temperature handling > > misc: emif: add one-time settings > > misc: emif: add debugfs entries for emif > > > > Documentation/misc-devices/ti-emif.txt | 58 ++ > > drivers/misc/Kconfig | 12 + > > drivers/misc/Makefile | 1 + > > drivers/misc/emif.c | 1670 > > +++++++++++++++++++++++++++++++ > > drivers/misc/emif.h | 589 +++++++++++ > > include/linux/platform_data/emif_plat.h | 128 +++ > > include/misc/jedec_ddr.h | 175 ++++ > > lib/Kconfig | 8 + > > lib/Makefile | 2 + > > lib/jedec_ddr_data.c | 135 +++ > > 10 files changed, 2778 insertions(+), 0 deletions(-) > > create mode 100644 Documentation/misc-devices/ti-emif.txt > > create mode 100644 drivers/misc/emif.c > > create mode 100644 drivers/misc/emif.h > > create mode 100644 include/linux/platform_data/emif_plat.h > > create mode 100644 include/misc/jedec_ddr.h > > create mode 100644 lib/jedec_ddr_data.c > > > > > > _______________________________________________ > > linux-arm-kernel mailing list > > linux-arm-kernel@xxxxxxxxxxxxxxxxxxx > > http://lists.infradead.org/mailman/listinfo/linux-arm-kernel > > > -- MyungJoo Ham (함명주), PHD System S/W Lab, S/W Platform Team, Software Center Samsung Electronics Cell: +82-10-6714-2858 ÿ淸º{.nÇ+돴윯돪†+%듚ÿ깁負¥Šwÿº{.nÇ+돴¥Š{깸‰슙悖¶썳變}©옽Æ zÚ&j:+v돣 ? ®w?듺2듷솳鈺Ú&¢)傘«a뛴ÿÿ鎬z요z받쀺+껠šŽ듶¢jÿŠw療f
