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Diffstat (limited to 'Documentation/devicetree/bindings/arm/tegra/nvidia,tegra20-emc.txt')
| -rw-r--r-- | Documentation/devicetree/bindings/arm/tegra/nvidia,tegra20-emc.txt | 100 |
1 files changed, 100 insertions, 0 deletions
diff --git a/Documentation/devicetree/bindings/arm/tegra/nvidia,tegra20-emc.txt b/Documentation/devicetree/bindings/arm/tegra/nvidia,tegra20-emc.txt new file mode 100644 index 000000000000..4c33b29dc660 --- /dev/null +++ b/Documentation/devicetree/bindings/arm/tegra/nvidia,tegra20-emc.txt @@ -0,0 +1,100 @@ +Embedded Memory Controller + +Properties: +- name : Should be emc +- #address-cells : Should be 1 +- #size-cells : Should be 0 +- compatible : Should contain "nvidia,tegra20-emc". +- reg : Offset and length of the register set for the device +- nvidia,use-ram-code : If present, the sub-nodes will be addressed + and chosen using the ramcode board selector. If omitted, only one + set of tables can be present and said tables will be used + irrespective of ram-code configuration. + +Child device nodes describe the memory settings for different configurations and clock rates. + +Example: + + memory-controller@7000f400 { + #address-cells = < 1 >; + #size-cells = < 0 >; + compatible = "nvidia,tegra20-emc"; + reg = <0x7000f4000 0x200>; + } + + +Embedded Memory Controller ram-code table + +If the emc node has the nvidia,use-ram-code property present, then the +next level of nodes below the emc table are used to specify which settings +apply for which ram-code settings. + +If the emc node lacks the nvidia,use-ram-code property, this level is omitted +and the tables are stored directly under the emc node (see below). + +Properties: + +- name : Should be emc-tables +- nvidia,ram-code : the binary representation of the ram-code board strappings + for which this node (and children) are valid. + + + +Embedded Memory Controller configuration table + +This is a table containing the EMC register settings for the various +operating speeds of the memory controller. They are always located as +subnodes of the emc controller node. + +There are two ways of specifying which tables to use: + +* The simplest is if there is just one set of tables in the device tree, + and they will always be used (based on which frequency is used). + This is the preferred method, especially when firmware can fill in + this information based on the specific system information and just + pass it on to the kernel. + +* The slightly more complex one is when more than one memory configuration + might exist on the system. The Tegra20 platform handles this during + early boot by selecting one out of possible 4 memory settings based + on a 2-pin "ram code" bootstrap setting on the board. The values of + these strappings can be read through a register in the SoC, and thus + used to select which tables to use. + +Properties: +- name : Should be emc-table +- compatible : Should contain "nvidia,tegra20-emc-table". +- reg : either an opaque enumerator to tell different tables apart, or + the valid frequency for which the table should be used (in kHz). +- clock-frequency : the clock frequency for the EMC at which this + table should be used (in kHz). +- nvidia,emc-registers : a 46 word array of EMC registers to be programmed + for operation at the 'clock-frequency' setting. + The order and contents of the registers are: + RC, RFC, RAS, RP, R2W, W2R, R2P, W2P, RD_RCD, WR_RCD, RRD, REXT, + WDV, QUSE, QRST, QSAFE, RDV, REFRESH, BURST_REFRESH_NUM, PDEX2WR, + PDEX2RD, PCHG2PDEN, ACT2PDEN, AR2PDEN, RW2PDEN, TXSR, TCKE, TFAW, + TRPAB, TCLKSTABLE, TCLKSTOP, TREFBW, QUSE_EXTRA, FBIO_CFG6, ODT_WRITE, + ODT_READ, FBIO_CFG5, CFG_DIG_DLL, DLL_XFORM_DQS, DLL_XFORM_QUSE, + ZCAL_REF_CNT, ZCAL_WAIT_CNT, AUTO_CAL_INTERVAL, CFG_CLKTRIM_0, + CFG_CLKTRIM_1, CFG_CLKTRIM_2 + + emc-table@166000 { + reg = <166000>; + compatible = "nvidia,tegra20-emc-table"; + clock-frequency = < 166000 >; + nvidia,emc-registers = < 0 0 0 0 0 0 0 0 0 0 0 0 0 0 + 0 0 0 0 0 0 0 0 0 0 0 0 0 0 + 0 0 0 0 0 0 0 0 0 0 0 0 0 0 + 0 0 0 0 >; + }; + + emc-table@333000 { + reg = <333000>; + compatible = "nvidia,tegra20-emc-table"; + clock-frequency = < 333000 >; + nvidia,emc-registers = < 0 0 0 0 0 0 0 0 0 0 0 0 0 0 + 0 0 0 0 0 0 0 0 0 0 0 0 0 0 + 0 0 0 0 0 0 0 0 0 0 0 0 0 0 + 0 0 0 0 >; + }; |