imx6 Device Tree Pinctrl parsing

imx6 Device Tree Pinctrl parsing

Transferred from: http://zzjlzx.blog.chinaunix.net/uid-9688646-id-5680705.html

Recently in the porting of Linux, with the kernel version of 3.14.28, in the high version of the kernel source used in the device tree (device-tree), the device tree with the Pinctrl configuration, recorded.

1. General Settings

When configuring the serial port, the configuration information for the Pinctrl is as follows:

[CPP] view plain copy &uart2 {pinctrl-names = "default";      pinctrl-0 = <&pinctrl_uart2>;  Status = "Okay";    };  。。。。。。。。                  pinctrl_uart2:uart2grp {fsl,pins = < Mx6qdl_pad_sd4_dat7__uart2_tx_data 0x1b0b1  Mx6qdl_pad_sd4_dat4__uart2_rx_data 0x1b0b1 >; };
The mx6qdl_pad_sd4_dat7__uart2_tx_data here is defined in the Imx6dl-pinfunc.h file as follows:

[CPP] view plain copy mx6qdl_pad_sd4_dat7__uart2_tx_data 0x35c 0x744 0x000 0x2 0x0

Expand the configuration of the pin as follows: 0x35c 0x744 0x000 0x2 0x00x1b0b1

Want to know what these six values are, you can start from two ways: ① to find the interpretation of DTS files, that is, to see the kernel source, ② on the Internet to find relevant knowledge.

1.1 View the source code to the device tree file interpretation

First, there is an explanation of the first 5 variables in the Imx6dl-pinfunc.h file, as shown in the following figure:

To verify the 5 variables and find the meaning of the 6th variable, we open the code that reads the device tree file.

The file that reads the DTS file is: DRIVERS/PINCTRL/FREESCALE/PINCTRL-IMX.C, the implementation function is named: static int imx_pinctrl_parse_groups (... ), as follows:

[CPP] View plain copy static int imx_pinctrl_parse_groups (struct device_node *np,                       struct Imx_pin_group *grp,                       struct Imx_pinctrl_soc_info *info,                       u32 index)   {      int size, pin_size;       const __BE32 *list;      int i;      u32 config;        dev_dbg (Info->dev, "Group (%d):%s\n", index, Np->name);         if (Info->flags & Share_mux_conf_reg)           pin_size = share_ fsl_pin_size;      else  &NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBsp;  pin_size = fsl_pin_size;     /* initialise Group */      Grp->name = np->name;       /*      * The binding format is Fsl,pins =,  &nbs p;   * Do sanity check and calculate pins number      */      list = Of_ Get_property (NP, "Fsl,pins", &size);      if (!list) {           Dev_err (Info->dev, "no Fsl,pins property in Node%s\n", Np->full_name);           return-einval;     }       /* We do not check RET Urn since it's safe node passed down */      if (!size | | size% pin_size) {     & nbsp;    Dev_err (Info->dev, "Invalid Fsl,pins Property in Node%s\n", Np->full_name);           return-einval;