mvebu-mbus.txt (8069B)
1 2* Marvell MBus 3 4Required properties: 5 6- compatible: Should be set to one of the following: 7 marvell,armada370-mbus 8 marvell,armadaxp-mbus 9 marvell,armada375-mbus 10 marvell,armada380-mbus 11 marvell,kirkwood-mbus 12 marvell,dove-mbus 13 marvell,orion5x-88f5281-mbus 14 marvell,orion5x-88f5182-mbus 15 marvell,orion5x-88f5181-mbus 16 marvell,orion5x-88f6183-mbus 17 marvell,mv78xx0-mbus 18 19- address-cells: Must be '2'. The first cell for the MBus ID encoding, 20 the second cell for the address offset within the window. 21 22- size-cells: Must be '1'. 23 24- ranges: Must be set up to provide a proper translation for each child. 25 See the examples below. 26 27- controller: Contains a single phandle referring to the MBus controller 28 node. This allows to specify the node that contains the 29 registers that control the MBus, which is typically contained 30 within the internal register window (see below). 31 32Optional properties: 33 34- pcie-mem-aperture: This optional property contains the aperture for 35 the memory region of the PCIe driver. 36 If it's defined, it must encode the base address and 37 size for the address decoding windows allocated for 38 the PCIe memory region. 39 40- pcie-io-aperture: Just as explained for the above property, this 41 optional property contains the aperture for the 42 I/O region of the PCIe driver. 43 44* Marvell MBus controller 45 46Required properties: 47 48- compatible: Should be set to "marvell,mbus-controller". 49 50- reg: Device's register space. 51 Two or three entries are expected (see the examples below): 52 the first one controls the devices decoding window, 53 the second one controls the SDRAM decoding window and 54 the third controls the MBus bridge (only with the 55 marvell,armada370-mbus and marvell,armadaxp-mbus 56 compatible strings) 57 58Example: 59 60 soc { 61 compatible = "marvell,armada370-mbus", "simple-bus"; 62 #address-cells = <2>; 63 #size-cells = <1>; 64 controller = <&mbusc>; 65 pcie-mem-aperture = <0xe0000000 0x8000000>; 66 pcie-io-aperture = <0xe8000000 0x100000>; 67 68 internal-regs { 69 compatible = "simple-bus"; 70 71 mbusc: mbus-controller@20000 { 72 compatible = "marvell,mbus-controller"; 73 reg = <0x20000 0x100>, <0x20180 0x20>, <0x20250 0x8>; 74 }; 75 76 /* more children ...*/ 77 }; 78 }; 79 80** MBus address decoding window specification 81 82The MBus children address space is comprised of two cells: the first one for 83the window ID and the second one for the offset within the window. 84In order to allow to describe valid and non-valid window entries, the 85following encoding is used: 86 87 0xSIAA0000 0x00oooooo 88 89Where: 90 91 S = 0x0 for a MBus valid window 92 S = 0xf for a non-valid window (see below) 93 94If S = 0x0, then: 95 96 I = 4-bit window target ID 97 AA = windpw attribute 98 99If S = 0xf, then: 100 101 I = don't care 102 AA = 1 for internal register 103 104Following the above encoding, for each ranges entry for a MBus valid window 105(S = 0x0), an address decoding window is allocated. On the other side, 106entries for translation that do not correspond to valid windows (S = 0xf) 107are skipped. 108 109 soc { 110 compatible = "marvell,armada370-mbus", "simple-bus"; 111 #address-cells = <2>; 112 #size-cells = <1>; 113 controller = <&mbusc>; 114 115 ranges = <0xf0010000 0 0 0xd0000000 0x100000 116 0x01e00000 0 0 0xfff00000 0x100000>; 117 118 bootrom { 119 compatible = "marvell,bootrom"; 120 reg = <0x01e00000 0 0x100000>; 121 }; 122 123 /* other children */ 124 ... 125 126 internal-regs { 127 compatible = "simple-bus"; 128 ranges = <0 0xf0010000 0 0x100000>; 129 130 mbusc: mbus-controller@20000 { 131 compatible = "marvell,mbus-controller"; 132 reg = <0x20000 0x100>, <0x20180 0x20>, <0x20250 0x8>; 133 }; 134 135 /* more children ...*/ 136 }; 137 }; 138 139In the shown example, the translation entry in the 'ranges' property is what 140makes the MBus driver create a static decoding window for the corresponding 141given child device. Note that the binding does not require child nodes to be 142present. Of course, child nodes are needed to probe the devices. 143 144Since each window is identified by its target ID and attribute ID there's 145a special macro that can be use to simplify the translation entries: 146 147#define MBUS_ID(target,attributes) (((target) << 24) | ((attributes) << 16)) 148 149Using this macro, the above example would be: 150 151 soc { 152 compatible = "marvell,armada370-mbus", "simple-bus"; 153 #address-cells = <2>; 154 #size-cells = <1>; 155 controller = <&mbusc>; 156 157 ranges = < MBUS_ID(0xf0, 0x01) 0 0 0xd0000000 0x100000 158 MBUS_ID(0x01, 0xe0) 0 0 0xfff00000 0x100000>; 159 160 bootrom { 161 compatible = "marvell,bootrom"; 162 reg = <MBUS_ID(0x01, 0xe0) 0 0x100000>; 163 }; 164 165 /* other children */ 166 ... 167 168 internal-regs { 169 compatible = "simple-bus"; 170 #address-cells = <1>; 171 #size-cells = <1>; 172 ranges = <0 MBUS_ID(0xf0, 0x01) 0 0x100000>; 173 174 mbusc: mbus-controller@20000 { 175 compatible = "marvell,mbus-controller"; 176 reg = <0x20000 0x100>, <0x20180 0x20>, <0x20250 0x8>; 177 }; 178 179 /* other children */ 180 ... 181 }; 182 }; 183 184 185** About the window base address 186 187Remember the MBus controller allows a great deal of flexibility for choosing 188the decoding window base address. When planning the device tree layout it's 189possible to choose any address as the base address, provided of course there's 190a region large enough available, and with the required alignment. 191 192Yet in other words: there's nothing preventing us from setting a base address 193of 0xf0000000, or 0xd0000000 for the NOR device shown above, if such region is 194unused. 195 196** Window allocation policy 197 198The mbus-node ranges property defines a set of mbus windows that are expected 199to be set by the operating system and that are guaranteed to be free of overlaps 200with one another or with the system memory ranges. 201 202Each entry in the property refers to exactly one window. If the operating system 203chooses to use a different set of mbus windows, it must ensure that any address 204translations performed from downstream devices are adapted accordingly. 205 206The operating system may insert additional mbus windows that do not conflict 207with the ones listed in the ranges, e.g. for mapping PCIe devices. 208As a special case, the internal register window must be set up by the boot 209loader at the address listed in the ranges property, since access to that region 210is needed to set up the other windows. 211 212** Example 213 214See the example below, where a more complete device tree is shown: 215 216 soc { 217 compatible = "marvell,armadaxp-mbus", "simple-bus"; 218 controller = <&mbusc>; 219 220 ranges = <MBUS_ID(0xf0, 0x01) 0 0 0xd0000000 0x100000 /* internal-regs */ 221 MBUS_ID(0x01, 0x1d) 0 0 0xfff00000 0x100000 222 MBUS_ID(0x01, 0x2f) 0 0 0xf0000000 0x8000000>; 223 224 bootrom { 225 compatible = "marvell,bootrom"; 226 reg = <MBUS_ID(0x01, 0x1d) 0 0x100000>; 227 }; 228 229 devbus-bootcs { 230 ranges = <0 MBUS_ID(0x01, 0x2f) 0 0x8000000>; 231 232 /* NOR */ 233 nor { 234 compatible = "cfi-flash"; 235 reg = <0 0x8000000>; 236 bank-width = <2>; 237 }; 238 }; 239 240 pcie-controller { 241 compatible = "marvell,armada-xp-pcie"; 242 device_type = "pci"; 243 244 #address-cells = <3>; 245 #size-cells = <2>; 246 247 ranges = 248 <0x82000000 0 0x40000 MBUS_ID(0xf0, 0x01) 0x40000 0 0x00002000 /* Port 0.0 registers */ 249 0x82000000 0 0x42000 MBUS_ID(0xf0, 0x01) 0x42000 0 0x00002000 /* Port 2.0 registers */ 250 0x82000000 0 0x44000 MBUS_ID(0xf0, 0x01) 0x44000 0 0x00002000 /* Port 0.1 registers */ 251 0x82000000 0 0x48000 MBUS_ID(0xf0, 0x01) 0x48000 0 0x00002000 /* Port 0.2 registers */ 252 0x82000000 0 0x4c000 MBUS_ID(0xf0, 0x01) 0x4c000 0 0x00002000 /* Port 0.3 registers */ 253 0x82000800 0 0xe0000000 MBUS_ID(0x04, 0xe8) 0xe0000000 0 0x08000000 /* Port 0.0 MEM */ 254 0x81000800 0 0 MBUS_ID(0x04, 0xe0) 0xe8000000 0 0x00100000 /* Port 0.0 IO */>; 255 256 257 pcie@1,0 { 258 /* Port 0, Lane 0 */ 259 }; 260 }; 261 262 internal-regs { 263 compatible = "simple-bus"; 264 #address-cells = <1>; 265 #size-cells = <1>; 266 ranges = <0 MBUS_ID(0xf0, 0x01) 0 0x100000>; 267 268 mbusc: mbus-controller@20000 { 269 reg = <0x20000 0x100>, <0x20180 0x20>, <0x20250 0x8>; 270 }; 271 272 interrupt-controller@20000 { 273 reg = <0x20a00 0x2d0>, <0x21070 0x58>; 274 }; 275 }; 276 };