1 Altera Passive Serial SPI FPGA Manager 1 Altera Passive Serial SPI FPGA Manager
2 2
3 Altera FPGAs support a method of loading the b 3 Altera FPGAs support a method of loading the bitstream over what is
4 referred to as "passive serial". 4 referred to as "passive serial".
5 The passive serial link is not technically SPI 5 The passive serial link is not technically SPI, and might require extra
6 circuits in order to play nicely with other SP 6 circuits in order to play nicely with other SPI slaves on the same bus.
7 7
8 See https://www.altera.com/literature/hb/cyc/c 8 See https://www.altera.com/literature/hb/cyc/cyc_c51013.pdf
9 9
10 Required properties: 10 Required properties:
11 - compatible: Must be one of the following: 11 - compatible: Must be one of the following:
12 "altr,fpga-passive-serial", 12 "altr,fpga-passive-serial",
13 "altr,fpga-arria10-passive-serial" 13 "altr,fpga-arria10-passive-serial"
14 - reg: SPI chip select of the FPGA 14 - reg: SPI chip select of the FPGA
15 - nconfig-gpios: config pin (referred to as nC 15 - nconfig-gpios: config pin (referred to as nCONFIG in the manual)
16 - nstat-gpios: status pin (referred to as nSTA 16 - nstat-gpios: status pin (referred to as nSTATUS in the manual)
17 17
18 Optional properties: 18 Optional properties:
19 - confd-gpios: confd pin (referred to as CONF_ 19 - confd-gpios: confd pin (referred to as CONF_DONE in the manual)
20 20
21 Example: 21 Example:
22 fpga: fpga@0 { 22 fpga: fpga@0 {
23 compatible = "altr,fpga-passiv 23 compatible = "altr,fpga-passive-serial";
24 spi-max-frequency = <20000000> 24 spi-max-frequency = <20000000>;
25 reg = <0>; 25 reg = <0>;
26 nconfig-gpios = <&gpio4 9 GPIO 26 nconfig-gpios = <&gpio4 9 GPIO_ACTIVE_LOW>;
27 nstat-gpios = <&gpio4 11 GPIO_ 27 nstat-gpios = <&gpio4 11 GPIO_ACTIVE_LOW>;
28 confd-gpios = <&gpio4 12 GPIO_ 28 confd-gpios = <&gpio4 12 GPIO_ACTIVE_LOW>;
29 }; 29 };
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