| Kyle Swenson | 8d8f654 | 2021-03-15 11:02:55 -0600 | [diff] [blame^] | 1 | PPC4xx Clock Power Management (CPM) node |
| 2 | |
| 3 | Required properties: |
| 4 | - compatible : compatible list, currently only "ibm,cpm" |
| 5 | - dcr-access-method : "native" |
| 6 | - dcr-reg : < DCR register range > |
| 7 | |
| 8 | Optional properties: |
| 9 | - er-offset : All 4xx SoCs with a CPM controller have |
| 10 | one of two different order for the CPM |
| 11 | registers. Some have the CPM registers |
| 12 | in the following order (ER,FR,SR). The |
| 13 | others have them in the following order |
| 14 | (SR,ER,FR). For the second case set |
| 15 | er-offset = <1>. |
| 16 | - unused-units : specifier consist of one cell. For each |
| 17 | bit in the cell, the corresponding bit |
| 18 | in CPM will be set to turn off unused |
| 19 | devices. |
| 20 | - idle-doze : specifier consist of one cell. For each |
| 21 | bit in the cell, the corresponding bit |
| 22 | in CPM will be set to turn off unused |
| 23 | devices. This is usually just CPM[CPU]. |
| 24 | - standby : specifier consist of one cell. For each |
| 25 | bit in the cell, the corresponding bit |
| 26 | in CPM will be set on standby and |
| 27 | restored on resume. |
| 28 | - suspend : specifier consist of one cell. For each |
| 29 | bit in the cell, the corresponding bit |
| 30 | in CPM will be set on suspend (mem) and |
| 31 | restored on resume. Note, for standby |
| 32 | and suspend the corresponding bits can |
| 33 | be different or the same. Usually for |
| 34 | standby only class 2 and 3 units are set. |
| 35 | However, the interface does not care. |
| 36 | If they are the same, the additional |
| 37 | power saving will be seeing if support |
| 38 | is available to put the DDR in self |
| 39 | refresh mode and any additional power |
| 40 | saving techniques for the specific SoC. |
| 41 | |
| 42 | Example: |
| 43 | CPM0: cpm { |
| 44 | compatible = "ibm,cpm"; |
| 45 | dcr-access-method = "native"; |
| 46 | dcr-reg = <0x160 0x003>; |
| 47 | er-offset = <0>; |
| 48 | unused-units = <0x00000100>; |
| 49 | idle-doze = <0x02000000>; |
| 50 | standby = <0xfeff0000>; |
| 51 | suspend = <0xfeff791d>; |
| 52 | }; |