linux驱动 — regalator使用

Posted 2021-10-30 超凡东皇

Regulator，即LDO(low dropout regulator)，低压差 线性稳压器，简称稳压器。

本篇我们只讨论regalator api的使用，regalator 常用api如下：

/* regulator get and put */
struct regulator *__must_check regulator_get(struct device *dev, const char *id);
struct regulator *__must_check devm_regulator_get(struct device *dev, const char *id);
void regulator_put(struct regulator *regulator);
void devm_regulator_put(struct regulator *regulator);
 
/* regulator output control and status */
int __must_check regulator_enable(struct regulator *regulator);
int regulator_disable(struct regulator *regulator);
int regulator_force_disable(struct regulator *regulator);
int regulator_is_enabled(struct regulator *regulator);
int regulator_set_voltage(struct regulator *regulator, int min_uV, int max_uV);

使用示例：

以lcm显示屏有一个电源引脚是由regalator控制的为例，即reg-lcm-supply = <&mt6323_vgp3_reg>;

设备树

&lcm {
	reg-lcm-supply = <&mt6323_vgp3_reg>;
};

驱动代码

#include <linux/string.h>
#include <linux/wait.h>
#include <linux/platform_device.h>
#include <linux/pinctrl/consumer.h>
#include <linux/of_gpio.h>
#include <asm-generic/gpio.h>

#include <linux/kernel.h>
#include <linux/mm.h>
#include <linux/mm_types.h>
#include <linux/module.h>
#include <linux/types.h>
#include <linux/slab.h>
#include <linux/vmalloc.h>

#ifdef CONFIG_OF
#include <linux/of.h>
#include <linux/of_irq.h>
#include <linux/of_address.h>
#include <linux/of_device.h>
#include <linux/regulator/consumer.h>
#include <linux/clk.h>
#endif

static struct regulator *lcm_vgp;

/* get LDO supply */
static int lcm_get_vgp_supply(struct device *dev)
{
	int ret;
	struct regulator *lcm_vgp_ldo;

	pr_debug("LCM: lcm_get_vgp_supply is going\\n");
	//从设备树中获取regulator，相当于一个gpio
	lcm_vgp_ldo = devm_regulator_get(dev, "reg-lcm");
	if (IS_ERR(lcm_vgp_ldo)) {
		ret = PTR_ERR(lcm_vgp_ldo);
		dev_err(dev, "failed to get reg-lcm LDO, %d\\n", ret);
		return ret;
	}

	pr_debug("LCM: lcm get supply ok.\\n");

	/* get current voltage settings */
	ret = regulator_get_voltage(lcm_vgp_ldo);
	pr_debug("lcm LDO voltage = %d in LK stage\\n", ret);

	lcm_vgp = lcm_vgp_ldo;

	return ret;
}

int lcm_vgp_supply_enable(void)
{
	int ret;
	unsigned int volt;

	pr_debug("LCM: lcm_vgp_supply_enable\\n");

	if (NULL == lcm_vgp)
		return 0;

	pr_debug("LCM: set regulator voltage lcm_vgp voltage to 2.8V\\n");
	/* 调节电压的最小和最大输出, set voltage to 1.8V */
	ret = regulator_set_voltage(lcm_vgp, 1800000, 1800000);
	if (ret != 0) {
		pr_err("LCM: lcm failed to set lcm_vgp voltage: %d\\n", ret);
		return ret;
	}

	/* 获取配置的输出电压, get voltage settings again */
	volt = regulator_get_voltage(lcm_vgp);
	if (volt == 1800000)
		pr_err("LCM: check regulator voltage=2800000 pass!\\n");
	else
		pr_err("LCM: check regulator voltage=2800000 fail! (voltage: %d)\\n", volt);
	//使能电源输出
	ret = regulator_enable(lcm_vgp);
	if (ret != 0) {
		pr_err("LCM: Failed to enable lcm_vgp: %d\\n", ret);
		return ret;
	}

	return ret;
}

int lcm_vgp_supply_disable(void)
{
	int ret = 0;
	unsigned int isenable;

	if (NULL == lcm_vgp)
		return 0;

	//判断regulator是否使能，大于0表示已经使能
	isenable = regulator_is_enabled(lcm_vgp);

	pr_debug("LCM: lcm query regulator enable status[0x%d]\\n", isenable);

	if (isenable) {
		//关闭电源输出
		ret = regulator_disable(lcm_vgp);
		if (ret != 0) {
			pr_err("LCM: lcm failed to disable lcm_vgp: %d\\n", ret);
			return ret;
		}
		/* verify */
		isenable = regulator_is_enabled(lcm_vgp);
		if (!isenable)
			pr_err("LCM: lcm regulator disable pass\\n");
	}

	return ret;
}

static int lcm_probe(struct device *dev)
{
	lcm_get_vgp_supply(dev);
	return 0;
}

static const struct of_device_id lcm_of_ids[] = {
	{.compatible = "mediatek,lcm",},
	{}
};

static struct platform_driver lcm_driver = {
	.driver = {
		   .name = "mtk_lcm",
		   .owner = THIS_MODULE,
		   .probe = lcm_probe,
#ifdef CONFIG_OF
		   .of_match_table = lcm_of_ids,
#endif
		   },
};

static int __init lcm_init(void)
{
	pr_debug("LCM: Register lcm driver\\n");
	if (platform_driver_register(&lcm_driver)) {
		pr_err("LCM: failed to register disp driver\\n");
		return -ENODEV;
	}

	return 0;
}

static void __exit lcm_exit(void)
{
	platform_driver_unregister(&lcm_driver);
	pr_debug("LCM: Unregister lcm driver done\\n");
}
late_initcall(lcm_init);
module_exit(lcm_exit);
MODULE_AUTHOR("mediatek");
MODULE_DESCRIPTION("Display subsystem Driver");
MODULE_LICENSE("GPL");

参考链接：

https://blog.csdn.net/spongebob1912/article/details/109517707

https://www.cnblogs.com/hellokitty2/p/9975711.html