matrix_keypad 矩阵按键驱动分析

//主要函数调用过程

matrix_keypad_probe

matrix_keypad_parse_dt //根据设备树构造 pdata

pdata->num_row_gpios = nrow = of_gpio_named_count(np, "row-gpios");

pdata->num_col_gpios = ncol = of_gpio_named_count(np, "col-gpios");

of_get_property(np, "linux,no-autorepeat", NULL)

of_get_property(np, "linux,wakeup", NULL)

of_get_property(np, "gpio-activelow", NULL)

of_property_read_u32(np, "debounce-delay-ms", &pdata->debounce_ms);

of_property_read_u32(np, "col-scan-delay-us",&pdata->col_scan_delay_us);

for (i = 0; i < pdata->num_row_gpios; i++)

gpios[i] = of_get_named_gpio(np, "row-gpios", i);

for (i = 0; i < pdata->num_col_gpios; i++)

gpios[pdata->num_row_gpios + i] = of_get_named_gpio(np, "col-gpios", i)

matrix_keypad_build_keymap

matrix_keypad_parse_of_keymap

of_get_property(np, "linux,keymap", &proplen);

matrix_keypad_map_key(input_dev, rows, cols, row_shift, key)

unsigned int row = KEY_ROW(key);

unsigned int col = KEY_COL(key);

unsigned short code = KEY_VAL(key);

keymap[MATRIX_SCAN_CODE(row, col, row_shift)] = code;

__set_bit(code, input_dev->keybit);

matrix_keypad_init_gpio

gpio_request(pdata->col_gpios[i], "matrix_kbd_col")

gpio_direction_output(pdata->col_gpios[i], !pdata->active_low);

gpio_request(pdata->row_gpios[i], "matrix_kbd_row");

gpio_direction_input(pdata->row_gpios[i]);

request_any_context_irq

input_register_device

//具体分析

//矩阵按键驱动源码在”drivers/input/keyboard/matrix_keypad.c”中

static int matrix_keypad_probe(struct platform_device *pdev)

{

const struct matrix_keypad_platform_data *pdata;

struct matrix_keypad *keypad;

struct input_dev *input_dev;

int err;

pdata = dev_get_platdata(&pdev->dev); // 获取设备的platform_data ；这个应该时传统的 平台设备匹配模型。

if (!pdata) {

//如果执行到这里，说明不是使用传统的平台设备模型，而是使用 设备树进行匹配的；

// 那么接下来的重点就是分析 matrix_keypad_parse_dt

pdata = matrix_keypad_parse_dt(&pdev->dev); //根据设备树的信息，构造 pdata

if (IS_ERR(pdata)) {

dev_err(&pdev->dev, "no platform data defined\n");

return PTR_ERR(pdata);

}

} else if (!pdata->keymap_data) {

dev_err(&pdev->dev, "no keymap data defined\n");

return -EINVAL;

}

keypad = kzalloc(sizeof(struct matrix_keypad), GFP_KERNEL);

input_dev = input_allocate_device();

..

keypad->input_dev = input_dev;

keypad->pdata = pdata;

keypad->row_shift = get_count_order(pdata->num_col_gpios);

keypad->stopped = true;

INIT_DELAYED_WORK(&keypad->work, matrix_keypad_scan);

spin_lock_init(&keypad->lock);

input_dev->name= pdev->name;

input_dev->id.bustype= BUS_HOST;

input_dev->dev.parent= &pdev->dev;

input_dev->open= matrix_keypad_start;

input_dev->close= matrix_keypad_stop;

err = matrix_keypad_build_keymap(pdata->keymap_data, NULL,

pdata->num_row_gpios,

pdata->num_col_gpios,

NULL, input_dev); //从 keymap_data 里分解出行列键对应的键码；或 从设备树里获取 keymap

..

if (!pdata->no_autorepeat)

__set_bit(EV_REP, input_dev->evbit); //按键的重复性时间

input_set_capability(input_dev, EV_MSC, MSC_SCAN);

input_set_drvdata(input_dev, keypad); //设置输入设备的私有数据为 keypad

err = matrix_keypad_init_gpio(pdev, keypad);//注册行线的中断号

..

err = input_register_device(keypad->input_dev);//注册输入设备

..

device_init_wakeup(&pdev->dev, pdata->wakeup);

platform_set_drvdata(pdev, keypad);

return 0;

...

return err;

}

//根据设备树的信息，构造 pdata

static struct matrix_keypad_platform_data *matrix_keypad_parse_dt(struct device *dev)

{

struct matrix_keypad_platform_data *pdata;

struct device_node *np = dev->of_node;

unsigned int *gpios;

int i, nrow, ncol;

..

//分配一块内存给 pdata

pdata = devm_kzalloc(dev, sizeof(*pdata), GFP_KERNEL);

...

pdata->num_row_gpios = nrow = of_gpio_named_count(np, "row-gpios");//获取GPIO引脚的个数

pdata->num_col_gpios = ncol = of_gpio_named_count(np, "col-gpios");

...

if (of_get_property(np, "linux,no-autorepeat", NULL))

pdata->no_autorepeat = true;

if (of_get_property(np, "linux,wakeup", NULL))

pdata->wakeup = true;

if (of_get_property(np, "gpio-activelow", NULL))

pdata->active_low = true;

of_property_read_u32(np, "debounce-delay-ms", &pdata->debounce_ms);//按键的消抖延迟

of_property_read_u32(np, "col-scan-delay-us",

&pdata->col_scan_delay_us); //扫描延迟

gpios = devm_kzalloc(dev,

sizeof(unsigned int) *

(pdata->num_row_gpios + pdata->num_col_gpios),

GFP_KERNEL);

...

// 获取GPIO引脚

for (i = 0; i < pdata->num_row_gpios; i++)

gpios[i] = of_get_named_gpio(np, "row-gpios", i);//获取 属性为 "row-gpios" 的第 i 个数据

for (i = 0; i < pdata->num_col_gpios; i++)

gpios[pdata->num_row_gpios + i] =

of_get_named_gpio(np, "col-gpios", i);

pdata->row_gpios = gpios;

pdata->col_gpios = &gpios[pdata->num_row_gpios];

return pdata;

}

int matrix_keypad_build_keymap(const struct matrix_keymap_data *keymap_data,

const char *keymap_name,

unsigned int rows, unsigned int cols,

unsigned short *keymap,

struct input_dev *input_dev)

{

unsigned int row_shift = get_count_order(cols);

size_t max_keys = rows << row_shift;

int i;

int error;

...

if (!keymap) {

keymap = devm_kzalloc(input_dev->dev.parent,

max_keys * sizeof(*keymap),

GFP_KERNEL);

...

}

}

input_dev->keycode = keymap;

input_dev->keycodesize = sizeof(*keymap);

input_dev->keycodemax = max_keys;

__set_bit(EV_KEY, input_dev->evbit);

if (keymap_data) {

for (i = 0; i < keymap_data->keymap_size; i++) {

unsigned int key = keymap_data->keymap[i];

if (!matrix_keypad_map_key(input_dev, rows, cols,

row_shift, key))

return -EINVAL;

}

} else {

//如果 keymap_data 为NULL时，则从设备树里 获取 ； 那么重点就是解析设备树里的数据了

error = matrix_keypad_parse_of_keymap(keymap_name, rows, cols, input_dev);

...

}

__clear_bit(KEY_RESERVED, input_dev->keybit);

return 0;

}

//就是解析设备树节点里的 linux,keymap 属性

static int matrix_keypad_parse_of_keymap(const char *propname,

unsigned int rows, unsigned int cols,

struct input_dev *input_dev)

{

struct device *dev = input_dev->dev.parent;

struct device_node *np = dev->of_node;

unsigned int row_shift = get_count_order(cols);

unsigned int max_keys = rows << row_shift;

unsigned int proplen, i, size;

const __be32 *prop;

if (!np)

return -ENOENT;

if (!propname)

propname = "linux,keymap";

// 获取节点属性值里的首地址

prop = of_get_property(np, propname, &proplen);

...

size = proplen / sizeof(u32);

...

for (i = 0; i < size; i++) {

unsigned int key = be32_to_cpup(prop + i);//获取属性值

if (!matrix_keypad_map_key(input_dev, rows, cols, row_shift, key)) //设置 keymap

return -EINVAL;

}

return 0;

}

static bool matrix_keypad_map_key(struct input_dev *input_dev,

unsigned int rows, unsigned int cols,

unsigned int row_shift, unsigned int key)

{

unsigned short *keymap = input_dev->keycode;

unsigned int row = KEY_ROW(key);

unsigned int col = KEY_COL(key);

unsigned short code = KEY_VAL(key);

...

keymap[MATRIX_SCAN_CODE(row, col, row_shift)] = code;

__set_bit(code, input_dev->keybit);

return true;

}

/*

列线作为输出，行线作为中断输入

*/

static int matrix_keypad_init_gpio(struct platform_device *pdev, struct matrix_keypad *keypad)

{

const struct matrix_keypad_platform_data *pdata = keypad->pdata;

int i, err;

/* initialized strobe lines as outputs, activated */

for (i = 0; i < pdata->num_col_gpios; i++) {

err = gpio_request(pdata->col_gpios[i], "matrix_kbd_col"); //请求IO

...

gpio_direction_output(pdata->col_gpios[i], !pdata->active_low);//设置为输出

}

for (i = 0; i < pdata->num_row_gpios; i++) {

err = gpio_request(pdata->row_gpios[i], "matrix_kbd_row");//请求io

...

gpio_direction_input(pdata->row_gpios[i]);//设置为输入

}

if (pdata->clustered_irq > 0) {

err = request_any_context_irq(pdata->clustered_irq,

matrix_keypad_interrupt,

pdata->clustered_irq_flags,

"matrix-keypad", keypad);

...

} else {

for (i = 0; i < pdata->num_row_gpios; i++) {

err = request_any_context_irq(

gpio_to_irq(pdata->row_gpios[i]),

matrix_keypad_interrupt,

IRQF_TRIGGER_RISING |

IRQF_TRIGGER_FALLING,

"matrix-keypad", keypad);

...

}

}

/* initialized as disabled - enabled by input->open */

disable_row_irqs(keypad);

return 0;

...

return err;

}

通过probe函数，可以确定我们写平台设备时只需通过platform_data成员提供平台驱动所需的信息，无需再提供resource.

再确定结构体matrix_keypad_platform_data的每个成员的作用即可,如不清楚具体用途，可以在驱动代码里通过查看对成员值的访问反推出用途.

在"include/linux/input/matrix_keypad.h"中有

#define KEY(row, col, val) ((((row) & (MATRIX_MAX_ROWS - 1)) << 24) |\

(((col) & (MATRIX_MAX_COLS - 1)) << 16) |\

((val) & 0xffff))

.....

#define KEY_ROW(k) (((k) >> 24) & 0xff)

#define KEY_COL(k) (((k) >> 16) & 0xff)

#define KEY_VAL(k) ((k) & 0xffff)

.....

.....

#define MATRIX_SCAN_CODE(row, col, row_shift) (((row) << (row_shift)) + (col))

......

......

struct matrix_keymap_data {

const uint32_t *keymap; //装载按键对应的键码数组, 注意每个键码需要使用宏KEY来写。也就是一个32位数据里，行，列，键码各占用8, 8, 16位.

unsigned int keymap_size; //键码数组的元素个数

};

......

......

struct matrix_keypad_platform_data {

const struct matrix_keymap_data *keymap_data; //键码数据对象的首地址

const unsigned int *row_gpios; //行线用的IO口

const unsigned int *col_gpios; //列线用的IO口

unsigned int num_row_gpios; //多少个行线

unsigned int num_col_gpios; //多少个列线

unsigned int col_scan_delay_us; //扫描列线时间隔时间

unsigned int debounce_ms; //防抖动的间隔时间

unsigned int clustered_irq; //行线是否共用一个中断, 设0则每个行线的中断是独立的

unsigned int clustered_irq_flags;

bool active_low; //键按下时，行线是否为低电平

bool wakeup;

bool no_autorepeat; //按键按下时是否重复提交按键, 设1就是不重复,设0重复

};

Linux中输入设备的事件类型有：

EV_SYN 0x00 同步事件

EV_KEY 0x01 按键事件，如KEY_VOLUMEDOWN

EV_REL 0x02 相对坐标, 如shubiao上报的坐标

EV_ABS 0x03 绝对坐标，如触摸屏上报的坐标

EV_MSC 0x04 其它

EV_LED 0x11 LED

EV_SND 0x12 声音

EV_REP 0x14 Repeat

EV_FF 0x15 力反馈

IMX6UL上添加支持矩阵按键(里面有设备树的配置信息)：

https://blog.csdn.net/qq_39346729/article/details/103293553