使用pinctrl子系统实现引脚功能动态切换
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使用pinctrl子系统实现动态切换引脚功能
设备dts （msm8909-pinctrl.dtsi）
&soc {
tlmm_pinmux:pinctrl@1000000 {
compatible= "qcom,msm-tlmm-8916";
reg= <0x1000000 0x300000>;
interrupts= <0 208 0>;
/*Generalpurpose pins*/
gp:gp {
qcom,num-pins= <113>;
#qcom,pin-cells= <1>;
msm_gpio:msm_gpio {
compatible= "qcom,msm-tlmm-gp";
gpio-controller;
#gpio-cells= <2>;
interrupt-controller;
#interrupt-cells= <2>;
num_irqs= <113>;
};
};
cam_sensor_mclk0{
/*MCLK */
qcom,pins= <&gp 26>;
qcom,num-grp-pins= <1>;
qcom,pin-func= <1>;
label= "cam-sensor-mclk0";
/* active state */
cam_sensor_mclk0_default:default {
drive-strength= <2>; /* 2 MA */
bias-disable= <0>; /* No PULL */
};
};
cam_sensor_mclk0_sleep{
/*MCLK */
qcom,pins= <&gp 26>;
qcom,num-grp-pins= <1>;
label= "cam-sensor-mclk0-sleep";
/*suspend state */
cam_sensor_mclk0_sleep:sleep {
drive-strength= <2>; /* 2 MA */
bias-pull-down;/* PULL DOWN */
};
};
/*test */
uart_0_console{
qcom,pins= <&gp 4>, <&gp 5>;
qcom,num-grp-pins= <2>;
qcom,pin-func= <2>;
label= "uart0-console";
uart_0_active:uart_0_active {
drive-strength = <8>;
bias-pull-down;
};
};
uart_0_gpio{
qcom,pins= <&gp 4>, <&gp 5>;
qcom,num-grp-pins= <2>;
qcom,pin-func= <0>;
label= "uart0-gpio";
uart_0_gpio:uart_0_gpio {
drive-strength = <8>;
bias-pull-down;
output-high;
};
};
};
};
定义串口引脚的两个状态uart_0_console（uart_0_active）和uart_0_gpio（uart_0_gpio）。
前者是配置gpio4/5作为uart功能，function2。后者配置gpio4,5作为普通gpio功能，function0。
具体设备引用：
&soc {
gpio_uart_exchage{
compatible= "gpio-uart-exchage";
pinctrl-names= "default", "gpio";
pinctrl-0= <&uart_0_active>;
pinctrl-1= <&uart_0_gpio>;
};
};
注意：
"default"对应的引脚配置为pinctrl-0；
"gpio"对应的引脚配置为pinctrl-1；
一般引脚的状态为两个就可以了，一个为活跃状态的引脚状态，一个是休眠状态的引脚状态。
如SDIO接口配置;
pinctrl-names= "active", "sleep";
pinctrl-0= <&sdc2_clk_on &sdc2_cmd_on &sdc2_data_on &sdc2_cd_on>;
pinctrl-1= <&sdc2_clk_off &sdc2_cmd_off &sdc2_data_off&sdc2_cd_off>;
站在应用的逻辑上来讲，设置某模块的两种工作状态。
驱动
设备配置好了，我们来看驱动程序。
首先介绍下主要pinctrl函数（Core.c (drivers\pinctrl)）
头文件：#include <linux/pinctrl/consumer.h>
参考：http://blog.csdn.net/hanp_linux/article/details/72818437
1. 获取一个pinctrl句柄，参数是dev是包含这个pin的device结构体即xxx这个设备的device
[cpp] view plain copy
/**
* struct devm_pinctrl_get() - Resource managed pinctrl_get()
* @dev: the device to obtain the handle for
*
* If there is a need to explicitly destroy the returned struct pinctrl,
* devm_pinctrl_put() should be used, rather than plain pinctrl_put().
*/
struct pinctrl *devm_pinctrl_get(struct device *dev)
2. 获取这个pin对应pin_state，引脚状态
[cpp] view plain copy
/**
* pinctrl_lookup_state() - retrieves a state handle from a pinctrl handle
* @p: the pinctrl handle to retrieve the state from
* @name: the state name to retrieve
*/
struct pinctrl_state *pinctrl_lookup_state(struct pinctrl *p, const char *name)
3.设置引脚为为某个state
[cpp] view plain copy
/**
* pinctrl_select_state() - select/activate/program a pinctrl state to HW
* @p: the pinctrl handle for the device that requests configuration
* @state: the state handle to select/activate/program
*/
int pinctrl_select_state(struct pinctrl *p, struct pinctrl_state *state)
下面是一个简单驱动程序：
#define pr_fmt(fmt) "%s:" fmt, __func__ #include <linux/init.h>#include <linux/module.h>#include <linux/fs.h>#include <linux/slab.h>#include<linux/miscdevice.h>#include <linux/delay.h>#include <linux/io.h>#include<linux/uaccess.h>#include<linux/regulator/consumer.h>#include <linux/pinctrl/consumer.h>#include<linux/platform_device.h>#include <linux/mutex.h>#include <linux/of.h>#include <linux/gpio.h> unsigned long isGPIO =0; struct pinctrl *gp_pinctrl;struct pinctrl_state*gp_default;//uartstruct pinctrl_state*gp_gpio;//gpio const char*gp_PINCTRL_STATE_DEFAULT = "default";const char*gp_PINCTRL_STATE_GPIO = "gpio"; static int gp_request_gpios(intstate){ int result = 0; if(state){ result = pinctrl_select_state(gp_pinctrl, gp_default); if (result) { printk("%s: Can not set %s pins\n", __func__, "default"); } }else{ result = pinctrl_select_state(gp_pinctrl, gp_gpio); if (result) { printk("%s: Can not set %s pins\n", __func__, "gpio"); } } printk(KERN_ERR "%s, eliot request state(%s) ok, result = %d\n", __func__, state ? "default" : "gpio",result); return result;}static ssize_t lock_show(structdevice* cd,struct device_attribute *attr, char* buf) { ssize_t ret = 0; sprintf(buf, "%lu\n",isGPIO); ret = strlen(buf) + 1; return ret; } static ssize_tlock_store(struct device* cd, struct device_attribute *attr, const char* buf, size_tlen) { unsigned long on_off = simple_strtoul(buf, NULL, 10); isGPIO = on_off; printk("%s: %lu\n",__func__, isGPIO); gp_request_gpios(!!isGPIO); if(!isGPIO){ printk(KERN_ERR "set gpio 4 & 5to 0\n"); gpio_set_value(4 + 911, !!isGPIO); gpio_set_value(5 + 911, !!isGPIO); } return len; }static DEVICE_ATTR(gp_ex,S_IRUGO | S_IWUSR, lock_show, lock_store); static intgp_pinctrl_init(struct platform_device *pdata){ gp_pinctrl = devm_pinctrl_get(&pdata->dev); if (IS_ERR_OR_NULL(gp_pinctrl)) { printk("Failed to get pin ctrl\n"); return PTR_ERR(gp_pinctrl); } // default gp_default = pinctrl_lookup_state(gp_pinctrl, gp_PINCTRL_STATE_DEFAULT); if (IS_ERR_OR_NULL(gp_default)) { printk("Failed to lookup pinctrl default state\n"); return PTR_ERR(gp_default); } // gpio gp_gpio = pinctrl_lookup_state(gp_pinctrl, gp_PINCTRL_STATE_GPIO); if (IS_ERR_OR_NULL(gp_gpio)) { printk("Failed to lookup pinctrl gpio state\n"); return PTR_ERR(gp_gpio); } printk("eliot %s,---ok\n", __func__); return 0; }// echo 0 >/sys/bus/platform/devices/gpio_uart_exchage.67/gp_ex //设置为普通GPIO// echo 1 >/sys/bus/platform/devices/gpio_uart_exchage.67/gp_ex //设置为UART模式static int gp_ex_probe(structplatform_device *pdev){ int ret = 0; printk(KERN_ERR "eliot :gp_ex_probe\n"); gp_pinctrl_init(pdev);if(device_create_file(&pdev->dev, &dev_attr_gp_ex)) printk(KERN_ERR "Unable to createsysfs entry: '%s'\n", dev_attr_gp_ex.attr.name); return ret; }static int gp_ex_remove(structplatform_device *plat){ return 0;} static struct of_device_id__attribute__ ((unused)) gp_ex_of_match[] = { { .compatible = "gpio-uart-exchage", }, {}}; static struct platform_drivergp_ex_driver = { .probe = gp_ex_probe, .remove = gp_ex_remove, .driver = { .name = "gpio-exchage", .owner = THIS_MODULE, .of_match_table = of_match_ptr(gp_ex_of_match), },}; static int __initgp_ex_init(void){ return platform_driver_register(&gp_ex_driver);} static void __exitgp_ex_exit(void){ platform_driver_unregister(&gp_ex_driver);} MODULE_LICENSE("GPLv2");MODULE_AUTHOR("Eliot shao<http://blog.csdn.net/eliot_shao>");MODULE_DESCRIPTION("Driverto exchager gpio4/5.");MODULE_VERSION("1.0"); module_init(gp_ex_init);module_exit(gp_ex_exit);
在sys文件系统下面创建一个节点，通过读写这个节点来设置gpio4,5的状态。使用方法：
// echo 0 >/sys/bus/platform/devices/gpio_uart_exchage.67/gp_ex //设置为普通GPIO
// echo 1 >/sys/bus/platform/devices/gpio_uart_exchage.67/gp_ex //设置为UART模式
其中调用的接口函数
int pinctrl_select_state(struct pinctrl *p, struct pinctrl_state *state)
来选择在dts中配置的两个引脚状态。
另外函数：
struct pinctrl_state *pinctrl_lookup_state(struct pinctrl *p, const char *name)
中的name在dts中pinctrl-names ="default", "gpio";配置，驱动中通过名称进行查找引脚状态。
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