matrix_keypad 矩陣按鍵驅動分析
//主要函數調用過程
matrix_keypad_probe
matrix_keypad_parse_dt //根據設備樹構造 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
//具體分析
//矩陣按鍵驅動源碼在”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); // 獲取設備的platform_data ;這個應該時傳統的 平臺設備匹配模型。
if (!pdata) {
//如果執行到這裏,說明不是使用傳統的平臺設備模型,而是使用 設備樹進行匹配的;
// 那麼接下來的重點就是分析 matrix_keypad_parse_dt
pdata = matrix_keypad_parse_dt(&pdev->dev); //根據設備樹的信息,構造 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); //從 keymap_data 裏分解出行列鍵對應的鍵碼;或 從設備樹裏獲取 keymap
..
if (!pdata->no_autorepeat)
__set_bit(EV_REP, input_dev->evbit); //按鍵的重複性時間
input_set_capability(input_dev, EV_MSC, MSC_SCAN);
input_set_drvdata(input_dev, keypad); //設置輸入設備的私有數據爲 keypad
err = matrix_keypad_init_gpio(pdev, keypad);//註冊行線的中斷號
..
err = input_register_device(keypad->input_dev);//註冊輸入設備
..
device_init_wakeup(&pdev->dev, pdata->wakeup);
platform_set_drvdata(pdev, keypad);
return 0;
...
return err;
}
//根據設備樹的信息,構造 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;
..
//分配一塊內存給 pdata
pdata = devm_kzalloc(dev, sizeof(*pdata), GFP_KERNEL);
...
pdata->num_row_gpios = nrow = of_gpio_named_count(np, "row-gpios");//獲取GPIO引腳的個數
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);//按鍵的消抖延遲
of_property_read_u32(np, "col-scan-delay-us",
&pdata->col_scan_delay_us); //掃描延遲
gpios = devm_kzalloc(dev,
sizeof(unsigned int) *
(pdata->num_row_gpios + pdata->num_col_gpios),
GFP_KERNEL);
...
// 獲取GPIO引腳
for (i = 0; i < pdata->num_row_gpios; i++)
gpios[i] = of_get_named_gpio(np, "row-gpios", i);//獲取 屬性爲 "row-gpios" 的第 i 個數據
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 爲NULL時,則從設備樹裏 獲取 ; 那麼重點就是解析設備樹裏的數據了
error = matrix_keypad_parse_of_keymap(keymap_name, rows, cols, input_dev);
...
}
__clear_bit(KEY_RESERVED, input_dev->keybit);
return 0;
}
//就是解析設備樹節點裏的 linux,keymap 屬性
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";
// 獲取節點屬性值裏的首地址
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);//獲取屬性值
if (!matrix_keypad_map_key(input_dev, rows, cols, row_shift, key)) //設置 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;
}
/*
列線作爲輸出,行線作爲中斷輸入
*/
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"); //請求IO
...
gpio_direction_output(pdata->col_gpios[i], !pdata->active_low);//設置爲輸出
}
for (i = 0; i < pdata->num_row_gpios; i++) {
err = gpio_request(pdata->row_gpios[i], "matrix_kbd_row");//請求io
...
gpio_direction_input(pdata->row_gpios[i]);//設置爲輸入
}
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;
}
通過probe函數,可以確定我們寫平臺設備時只需通過platform_data成員提供平臺驅動所需的信息,無需再提供resource.
再確定結構體matrix_keypad_platform_data的每個成員的作用即可,如不清楚具體用途,可以在驅動代碼裏通過查看對成員值的訪問反推出用途.
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; //裝載按鍵對應的鍵碼數組, 注意每個鍵碼需要使用宏KEY來寫。也就是一個32位數據裏,行,列,鍵碼各佔用8, 8, 16位.
unsigned int keymap_size; //鍵碼數組的元素個數
};
......
......
struct matrix_keypad_platform_data {
const struct matrix_keymap_data *keymap_data; //鍵碼數據對象的首地址
const unsigned int *row_gpios; //行線用的IO口
const unsigned int *col_gpios; //列線用的IO口
unsigned int num_row_gpios; //多少個行線
unsigned int num_col_gpios; //多少個列線
unsigned int col_scan_delay_us; //掃描列線時間隔時間
unsigned int debounce_ms; //防抖動的間隔時間
unsigned int clustered_irq; //行線是否共用一箇中斷, 設0則每個行線的中斷是獨立的
unsigned int clustered_irq_flags;
bool active_low; //鍵按下時,行線是否爲低電平
bool wakeup;
bool no_autorepeat; //按鍵按下時是否重複提交按鍵, 設1就是不重複,設0重複
};
Linux中輸入設備的事件類型有:
EV_SYN 0x00 同步事件
EV_KEY 0x01 按鍵事件,如KEY_VOLUMEDOWN
EV_REL 0x02 相對座標, 如shubiao上報的座標
EV_ABS 0x03 絕對座標,如觸摸屏上報的座標
EV_MSC 0x04 其它
EV_LED 0x11 LED
EV_SND 0x12 聲音
EV_REP 0x14 Repeat
EV_FF 0x15 力反饋
IMX6UL上添加支持矩陣按鍵(裏面有設備樹的配置信息):
https://blog.csdn.net/qq_39346729/article/details/103293553