Linux regulator系统（1）

1. 概念:
Regulator : 电源芯片, 比如电压转换芯片
Consumer : 消费者,使用电源的部件, Regulator是给Consumer供电的
machine : 单板,上面焊接有Regulator和Consumer
Constraints : 约束, 比如某个电源管理芯片输出的电压范围
Supply : 提供电源的部件, Regulator就是一个Supply; Regulator A可以给Regulator B供电, 那么Regulator B的Supply就是A

2. 写驱动程序:

(1). regulator驱动:
注册一个platform_driver: 在它的probe函数里分配、设置、注册一个regulator
"设置"里要做的事情: 实现regulator的操作, 比如enable, disable, set_voltage
(2). machine(单板)驱动:
注册一个platform_device: 在它的私有数据里指定regulator和consume的对应关系(这个电源芯片给哪一个部件供电)
指定约束条件(比如电压范围)
(3). consumer使用此电源的设备驱动:
使用即可: regulator_get, regulator_enable, regulator_disable, regulator_set_voltage....
注: 这只是没有使用设备树的情况下是这样的，其实就是以平台设备模型注册一个regulator，然后consumer去使用。

3. 不使用设备树的regulator_register流程分析:

    // 分配regulator_dev
    rdev = kzalloc(sizeof(struct regulator_dev), GFP_KERNEL);

    /* set regulator constraints */
    set_machine_constraints
    add_regulator_attributes
    
    /* add consumers devices */
    set_consumer_device_supply
        在regulator_map_list链表里生成一项regulator_map: 它里面有dev_name(consumer的名字),supply(cosumer的电源引脚名字)

    // 把regulator_dev放入regulator_list
    list_add(&rdev->list, &regulator_list);        

4. 使用设备树的regulator_register()和regulator_get()流程分析:

regulator_register(const struct regulator_desc *, const struct regulator_config *) //drivers/regulator/core.c
    先自行各种检查,然后构造一个struct regulator_dev，从设备树中获取它的各种属性
    regulator_of_get_init_data //drivers/regulator/of_regulator.c
        of_get_regulation_constraints //drivers/regulator/of_regulator.c 通过设备树构造init_data，和约束
            若设备树中指定了“regulator-initial-mode”且regulator_desc.of_map_mode()存在，则调用它
    初始化rdev->consumer_list，rdev->list，rdev->notifier，指定rdev->disable_work=regulator_disable_work
    如果init_data->regulator_init()存在则调用
    判断是不是gpio控制的regulator，如果是就调用regulator_ena_gpio_request()
    使rdev->dev.class = &regulator_class，此时sysfs下会有"regulator"文件夹，其下有regulator_dev_attrs中列出的文件。
    自动递增设置&rdev->dev的name为"regulator.%lu" "regulator"下的"regulator.%lu"下才会有regulator_dev_attrs中列出的文件了。
    set_machine_constraints
    device_register(&rdev->dev) //注册到设备模型
    dev_set_drvdata(&rdev->dev, rdev);
    rdev_init_debugfs(rdev);


使用设备树的regulator_get()流程分析:
struct regulator *regulator_get(struct device *dev, const char *id) //drivers/regulator/core.c， arg2为consumer的电源引脚
    regulator_dev_lookup //drivers/regulator/core.c
        使用devname与全局链表regulator_map_list中的每一项struct regulator_map->dev_name进行匹配，并返回匹配的struct regulator_dev结构体。
    regulator_resolve_supply 还要和rdev->supply_name的名字逐个比较
    create_regulator 根据struct regulator_dev创建一个struct regulator并返回

5.驱动示例代码

/* 文件名：machine.c 作为一个regulator平台设备模型的设备端。 
 * 参考: archarmmach-omap2oard-2430sdp.c
 * 这里只是注册一个单板的所有regulator的平台设备端，目前这类文件应该被设备树给替代了
 */

#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/err.h>
#include <linux/platform_device.h>
#include <linux/regulator/driver.h>
#include <linux/mfd/core.h>

/* 分配/设置/注册regulator_init_data */

#if 0
 regulator_consumer_supply:
 const char *dev_name;     /* consumer的名字 */
 const char *supply;     /* consumer的电源引脚名称 */

#endif

static struct regulator_consumer_supply myregulator_supplies[] = {
    REGULATOR_SUPPLY("VCC", "mylcd"), /*此regulator是对设备"mylcd"上的"VCC"引脚供电的*/
};


static struct regulator_init_data myregulator_init_data = {
    .constraints = {
        .min_uV            = 12000000,
        .max_uV            = 12000000,
        .valid_modes_mask    = REGULATOR_MODE_NORMAL,
        .valid_ops_mask        = REGULATOR_CHANGE_STATUS,
    },
    .num_consumer_supplies    = ARRAY_SIZE(myregulator_supplies),
    .consumer_supplies    = myregulator_supplies,
};

static void myregulator_release(struct device * dev)
{
}

static struct platform_device myregulator_dev = {
    .name         = "myregulator",  /* 平台设备设备端名字*/
    .id       = -1,
    .dev = { 
        .release       = myregulator_release, 
        .platform_data = &myregulator_init_data,
    },
};

/*使用设备树后就不再需要注册平台设备端了*/
static int myregulator_machine_init(void)
{
    platform_device_register(&myregulator_dev);
    return 0;
}

static void myregulator_machine_exit(void)
{
    platform_device_unregister(&myregulator_dev);
}

module_init(myregulator_machine_init);
module_exit(myregulator_machine_exit);

MODULE_LICENSE("GPL v2");

/* 文件名：regulator.c 作为一个regulator平台设备模型的驱动端。 
 * 参考: drivers/regulator/tps6105x-regulator.c 
 * 其实machine.c充当的是平台设备的设备端，将单板上的所有regulator写在了一起，目前已被设备树替代。
 * regulator.c充当的是平台设备的驱动端，每个regulator都可能有一个平台设备驱动端。
 */

#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/err.h>
#include <linux/platform_device.h>
#include <linux/regulator/driver.h>
#include <linux/mfd/core.h>

static volatile unsigned long *gpbcon;
static volatile unsigned long *gpbdat;

static int myregulator_enable(struct regulator_dev *rdev)
{
    *gpbdat |= 1;     /* 输出高电平 */
    return 0;
}

static int myregulator_disable(struct regulator_dev *rdev)
{
    *gpbdat &= ~1;     /* 输出低电平 */
    return 0;
}

static int myregulator_is_enabled(struct regulator_dev *rdev)
{
    if (*gpbdat & 1)
        return 1;
    else
        return 0;
}


static struct regulator_ops myregulator_ops = {
    .enable        = myregulator_enable,
    .disable    = myregulator_disable,
    .is_enabled    = myregulator_is_enabled,
};


static struct regulator_desc myregulator_desc = {
    .name        = "myregulator",
    .ops        = &myregulator_ops,
    .type        = REGULATOR_VOLTAGE,
    .id        = 0,
    .owner        = THIS_MODULE,
    .n_voltages    = 1, /*只提供一种电压值得*/
};

static struct regulator_dev *myregulator_dev;
static int myregulator_probe(struct platform_device *pdev)
{
    struct regulator_init_data *init_data = dev_get_platdata(&pdev->dev); /*可以在platform_driver初始化的时候对dev赋值*//* 分配/设置/注册 regulator */
    myregulator_dev = regulator_register(&myregulator_desc,
                         &pdev->dev,
                         init_data, NULL,
                         NULL);

    if (IS_ERR(myregulator_dev)) {
        printk("regulator_register error!
");
        return -EIO;
    }

    return 0;
}

static int myregulator_remove(struct platform_device *pdev)
{
    regulator_unregister(myregulator_dev);
    return 0;
}

struct platform_driver myregulator_drv = {
    .probe        = myregulator_probe,
    .remove        = myregulator_remove,
    .driver        = {
        .name    = "myregulator",  /* 驱动上面regulator平台设备的设备端 */
    }
};

static int myregulator_init(void)
{
    platform_driver_register(&myregulator_drv);
    return 0;
}

static void myregulator_exit(void)
{
    platform_driver_unregister(&myregulator_drv);
}

module_init(myregulator_init);
module_exit(myregulator_exit);

MODULE_LICENSE("GPL v2");

/* 文件名：consumer_lcd.c 作为一个consumer驱动
 * 
 */
static int mylcd_open(struct fb_info *info, int user)
{
    pm_runtime_get_sync(&lcd_dev.dev);
    return 0;
}
static int mylcd_release(struct fb_info *info, int user)
{
    pm_runtime_mark_last_busy(&lcd_dev.dev);
    pm_runtime_put_sync_autosuspend(&lcd_dev.dev);
    return 0;
}

static int lcd_suspend_notifier(struct notifier_block *nb,
                unsigned long event,
                void *dummy)
{

    switch (event) {
    case PM_SUSPEND_PREPARE:
        printk("lcd suspend notifiler test: PM_SUSPEND_PREPARE
");
        return NOTIFY_OK;
    case PM_POST_SUSPEND:
        printk("lcd suspend notifiler test: PM_POST_SUSPEND
");
        return NOTIFY_OK;

    default:
        return NOTIFY_DONE;
    }
}

static struct notifier_block lcd_pm_notif_block = {
    .notifier_call = lcd_suspend_notifier,
};

static void lcd_release(struct device * dev)
{
}

static struct platform_device lcd_dev = { /* regulator匹配1 */
    .name         = "mylcd",
    .id       = -1,
    .dev = { 
        .release = lcd_release, 
    },
};

static struct regulator *myregulator;

static int lcd_probe(struct platform_device *pdev)
{
    myregulator = regulator_get(pdev->dev, "VCC"); /* regulator 匹配2 */
    if (IS_ERR(myregulator)) {
        printk("regulator_get error!
");
        return -EIO;
    }
    regulator_enable(myregulator); /*没有它会报unblance regulator disable of myregulator*/

    pm_runtime_set_active(&pdev->dev);
    pm_runtime_use_autosuspend(&pdev->dev);
    pm_runtime_enable(&pdev->dev);
    return 0;
}
static int lcd_remove(struct platform_device *pdev)
{
    regulator_put(myregulator);
    pm_runtime_disable(&pdev->dev);
    return 0;
}
static int lcd_suspend(struct device *dev)
{
    int i;
    unsigned long *dest = &lcd_regs_backup;
    unsigned long *src  = lcd_regs;
    
    for (i = 0; i < sizeof(lcd_regs_backup)/sizeof(unsigned long); i++)
    {
        dest[i] = src[i];
    }
    
    lcd_regs->lcdcon1 &= ~(1<<0); /* 关闭LCD本身 */
    //*gpbdat &= ~1;     /* 关闭背光 */
    regulator_disable(myregulator);
    return 0;
}

static int lcd_resume(struct device *dev)
{
    int i;
    unsigned long *dest = lcd_regs;
    unsigned long *src  = &lcd_regs_backup;

    struct clk *clk = clk_get(NULL, "lcd");
    clk_enable(clk);
    clk_put(clk);

    for (i = 0; i < sizeof(lcd_regs_backup)/sizeof(unsigned long); i++)
    {
        dest[i] = src[i];
    }

    regulator_enable(myregulator);
    return 0;
}

static struct dev_pm_ops lcd_pm = {
    .suspend = lcd_suspend,
    .resume  = lcd_resume,    
    .runtime_suspend = lcd_suspend,
    .runtime_resume  = lcd_resume,    
};

struct platform_driver lcd_drv = {
    .probe        = lcd_probe,
    .remove        = lcd_remove,
    .driver        = {
        .name    = "mylcd",
        .pm     = &lcd_pm,
    }
};


static int lcd_init(void)
{    
    /* 电源管理 */
    register_pm_notifier(&lcd_pm_notif_block);

    platform_device_register(&lcd_dev);
    platform_driver_register(&lcd_drv);
    
    return 0;
}

static void lcd_exit(void)
{    
    unregister_pm_notifier(&lcd_pm_notif_block);
    platform_device_unregister(&lcd_dev);
    platform_driver_unregister(&lcd_drv);
}

module_init(lcd_init);
module_exit(lcd_exit);

MODULE_LICENSE("GPL");