JJJ - linux reset framework

基于 “arch/arm/mach-imx/src.c”
参考这篇

reset-framework涉及的文件：
include/linux/reset-controller.h
drivers/reset/core.c

总之感觉就是封装了一个设备的复位操作，并可以通过设备树去灵活配置复位操作

静态定义:

static struct reset_controller_dev imx_reset_controller = {
    .ops = &imx_src_ops,
    .nr_resets = ARRAY_SIZE(sw_reset_bits),
};


static const int sw_reset_bits[5] = {
    BP_SRC_SCR_SW_GPU_RST,
    BP_SRC_SCR_SW_VPU_RST,
    BP_SRC_SCR_SW_IPU1_RST,
    BP_SRC_SCR_SW_OPEN_VG_RST,
    BP_SRC_SCR_SW_IPU2_RST
};

关于ARRAY_SIZE这个宏，参考这篇blog

结构体类型定义

struct reset_controller_dev 类型

/**
 * struct reset_controller_dev - reset controller entity that might
 *                               provide multiple reset controls
 * @ops: a pointer to device specific struct reset_control_ops
 * @owner: kernel module of the reset controller driver
 * @list: internal list of reset controller devices
 * @of_node: corresponding device tree node as phandle target
 * @of_reset_n_cells: number of cells in reset line specifiers
 * @of_xlate: translation function to translate from specifier as found in the
 *            device tree to id as given to the reset control ops
 * @nr_resets: number of reset controls in this reset controller device
 */
struct reset_controller_dev {
    struct reset_control_ops *ops;
    struct module *owner;
    struct list_head list;
    struct device_node *of_node;
    int of_reset_n_cells;
    int (*of_xlate)(struct reset_controller_dev *rcdev,
            const struct of_phandle_args *reset_spec);
    unsigned int nr_resets;
};

struct reset_control定义：

/**
 * struct reset_control - a reset control
 * @rcdev: a pointer to the reset controller device
 *         this reset control belongs to
 * @id: ID of the reset controller in the reset
 *      controller device
 */
struct reset_control {
    struct reset_controller_dev *rcdev;
    struct device *dev;
    unsigned int id;
};

struct reset_control_ops定义

/**
 * struct reset_control_ops
 *
 * @reset: for self-deasserting resets, does all necessary
 *         things to reset the device
 * @assert: manually assert the reset line, if supported
 * @deassert: manually deassert the reset line, if supported
 * @status: return the status of the reset line, if supported
 */
struct reset_control_ops {
    int (*reset)(struct reset_controller_dev *rcdev, unsigned long id);
    int (*assert)(struct reset_controller_dev *rcdev, unsigned long id);
    int (*deassert)(struct reset_controller_dev *rcdev, unsigned long id);
    int (*status)(struct reset_controller_dev *rcdev, unsigned long id);
};

在函数 imx_src_init中

struct device_node *np;

np = of_find_compatible_node(NULL, NULL, "fsl,imx51-src");
...
imx_reset_controller.of_node = np;
    if (IS_ENABLED(CONFIG_RESET_CONTROLLER))
        reset_controller_register(&imx_reset_controller);
...

np对应的结点为：

            src: src@020d8000 {
                compatible = "fsl,imx6ul-src", "fsl,imx51-src";
                reg = <0x020d8000 0x4000>;
                interrupts = <GIC_SPI 91 IRQ_TYPE_LEVEL_HIGH>,
                         <GIC_SPI 96 IRQ_TYPE_LEVEL_HIGH>;
                #reset-cells = <1>;
            };

看reset_controller_register

/**
 * reset_controller_register - register a reset controller device
 * @rcdev: a pointer to the initialized reset controller device
 */
int reset_controller_register(struct reset_controller_dev *rcdev)
{
    if (!rcdev->of_xlate) {
        rcdev->of_reset_n_cells = 1;
        rcdev->of_xlate = of_reset_simple_xlate;
    }

    mutex_lock(&reset_controller_list_mutex);
    list_add(&rcdev->list, &reset_controller_list);
    mutex_unlock(&reset_controller_list_mutex);

    return 0;
}
EXPORT_SYMBOL_GPL(reset_controller_register);