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此文章仅作本人自己笔记使用，文章结束部分有本人调试过程，可以借鉴，由于没有仔细排版，所以可阅读性不高，读者见谅！一般按键驱动有两种，一个是矩阵键盘驱动，一个是GPIO接口键盘驱动矩阵键盘路径 ： kernel/driers/input/keyboard/matrix_keypad.c ：一般用于多按键的情况 （手机）GPIO接口键盘路径 ：kernel/driers/input/keyboard/gpio_keys.c ：一般用于少按键的情况键盘属于输入子系统范围adb shellcat /proc/bus/input/devices 得到 matrix_keypad设备信息修改 matrix_keypad 键盘相关设备树 msm8909-E8909-mtp.dtsi matrix_keypad键盘相关参数
代码如下//自定义矩阵按键 结构体struct matrix_keypad {const struct matrix_keypad_platform_data *pdata;struct input_dev *input_dev;unsigned int row_shift;DECLARE_BITMAP(disabled_gpios, MATRIX_MAX_ROWS);uint32_t last_key_state[MATRIX_MAX_COLS];struct delayed_work work;struct mutex lock;bool scan_pending;bool stopped;bool gpio_all_disabled;};static void __activate_col(const struct matrix_keypad_platform_data *pdata, int col, bool on){bool level_on = !pdata->active_low;if (on) { gpio_direction_output(pdata->col_gpios[col], level_on);} else { gpio_set_value_cansleep(pdata->col_gpios[col], !level_on); gpio_direction_input(pdata->col_gpios[col]);}}static void activate_col(const struct matrix_keypad_platform_data *pdata, int col, bool on){__activate_col(pdata, col, on);if (on && pdata->col_scan_delay_us) udelay(pdata->col_scan_delay_us);}static void activate_all_cols(const struct matrix_keypad_platform_data *pdata, bool on){int col;for (col = 0; col < pdata->num_col_gpios; col++) __activate_col(pdata, col, on);}static bool row_asserted(const struct matrix_keypad_platform_data *pdata, int row){return gpio_get_value_cansleep(pdata->row_gpios[row]) ? !pdata->active_low : pdata->active_low;}//使能中断static void enable_row_irqs(struct matrix_keypad *keypad){const struct matrix_keypad_platform_data *pdata = keypad->pdata;int i;if (pdata->clustered_irq > 0) enable_irq(pdata->clustered_irq);else { for (i = 0; i < pdata->num_row_gpios; i++) //使能中断 enable_irq(gpio_to_irq(pdata->row_gpios[i]));}}//关闭中断static void disable_row_irqs(struct matrix_keypad *keypad){const struct matrix_keypad_platform_data *pdata = keypad->pdata;int i;if (pdata->clustered_irq > 0) disable_irq_nosync(pdata->clustered_irq);else { for (i = 0; i < pdata->num_row_gpios; i++) //关闭中断 disable_irq_nosync(gpio_to_irq(pdata->row_gpios[i]));}}//按键扫描，中断处理机制下半部，用于扫描矩阵按键/* 按列扫描矩阵按键，矩阵按键的扫描原理请自行百度，此处不做详细说明 * 此函数功能是 ： * 1 ：扫描矩阵按键，并且将每一列按键的状态 按照按键所在行数 左移row位， * 这样每一列的按键状态都可以用一个数值表示，最终将多个列的按键状态（处理后的数值） * 存储在一个数组中， * 2 ：将扫描处理后的矩阵按键状态数值 上报 * */static void matrix_keypad_scan(struct work_struct *work){struct matrix_keypad *keypad = container_of(work, struct matrix_keypad, work.work);struct input_dev *input_dev = keypad->input_dev;const unsigned short *keycodes = input_dev->keycode;const struct matrix_keypad_platform_data *pdata = keypad->pdata;uint32_t new_state[MATRIX_MAX_COLS];int row, col, code;/* de-activate all columns for scanning */activate_all_cols(pdata, false); //把所有的列线改为输入功能 电压0memset(new_state, 0, sizeof(new_state));/* assert each column and read the row status out */for (col = 0; col < pdata->num_col_gpios; col++) {activate_col(pdata, col, true); //把指定的列线改为输出 for (row = 0; row < pdata->num_row_gpios; row++) { new_state[col] |= row_asserted(pdata, row) ? (1 << row) : 0; }activate_col(pdata, col, false); //把所有的列线改为输入功能}//检查按键状态，如果和上一次不一样 则上报事件 for (col = 0; col < pdata->num_col_gpios; col++) { uint32_t bits_changed; bits_changed = keypad->last_key_state[col] ^ new_state[col]; if (bits_changed == 0) continue; for (row = 0; row < pdata->num_row_gpios; row++) { if ((bits_changed & (1 << row)) == 0) continue; code = MATRIX_SCAN_CODE(row, col, keypad->row_shift);//提交输入事件input_event(input_dev, EV_MSC, MSC_SCAN, code);//提交按键值input_report_key(input_dev, keycodes[code], new_state[col] & (1 << row)); }}//同步input_sync(input_dev);memcpy(keypad->last_key_state, new_state, sizeof(new_state));activate_all_cols(pdata, true);mutex_lock(&keypad->lock);keypad->scan_pending = false;enable_row_irqs(keypad);mutex_unlock(&keypad->lock);}//中断函数 中断处理机制上半部static irqreturn_t matrix_keypad_interrupt(int irq, void *id) {
struct matrix_keypad *keypad = id; mutex_lock(&keypad->lock);/* * See if another IRQ beaten us to it and scheduled the * scan already. In that case we should not try to * disable IRQs again. */if (unlikely(keypad->scan_pending || keypad->stopped)) goto out;disable_row_irqs(keypad);keypad->scan_pending = true;//中断处理机制上半部,上半部处理后 调度一个延后的工作队列（下半部）schedule_delayed_work(&keypad->work,msecs_to_jiffies(keypad->pdata->debounce_ms));out:mutex_unlock(&keypad->lock);return IRQ_HANDLED;}static int matrix_keypad_start(struct input_dev *dev){struct matrix_keypad *keypad = input_get_drvdata(dev);keypad->stopped = false;mb();//调度一个延后的工作队列用来扫描矩阵键盘schedule_delayed_work(&keypad->work, 0);return 0;}static void matrix_keypad_stop(struct input_dev *dev){struct matrix_keypad *keypad = input_get_drvdata(dev);keypad->stopped = true;mb();flush_work(&keypad->work.work);/* * matrix_keypad_scan() will leave IRQs enabled; * we should disable them now. */disable_row_irqs(keypad);}#ifdef CONFIG_PM_SLEEPstatic void matrix_keypad_enable_wakeup(struct matrix_keypad *keypad) {
const struct matrix_keypad_platform_data *pdata = keypad->pdata; unsigned int gpio; int i;if (pdata->clustered_irq > 0) { if (enable_irq_wake(pdata->clustered_irq) == 0) keypad->gpio_all_disabled = true;} else { for (i = 0; i < pdata->num_row_gpios; i++) { if (!test_bit(i, keypad->disabled_gpios)) { gpio = pdata->row_gpios[i]; if (enable_irq_wake(gpio_to_irq(gpio)) == 0) __set_bit(i, keypad->disabled_gpios); } }} }
static void matrix_keypad_disable_wakeup(struct matrix_keypad *keypad){ const struct matrix_keypad_platform_data *pdata = keypad->pdata;unsigned int gpio;int i;if (pdata->clustered_irq > 0) { if (keypad->gpio_all_disabled) { disable_irq_wake(pdata->clustered_irq); keypad->gpio_all_disabled = false; }} else { for (i = 0; i < pdata->num_row_gpios; i++) { if (test_and_clear_bit(i, keypad->disabled_gpios)) { gpio = pdata->row_gpios[i]; disable_irq_wake(gpio_to_irq(gpio)); } }}}static int matrix_keypad_suspend(struct device *dev){struct platform_device *pdev = to_platform_device(dev);struct matrix_keypad *keypad = platform_get_drvdata(pdev);matrix_keypad_stop(keypad->input_dev);if (device_may_wakeup(&pdev->dev)) matrix_keypad_enable_wakeup(keypad);return 0;}static int matrix_keypad_resume(struct device *dev){struct platform_device *pdev = to_platform_device(dev);struct matrix_keypad *keypad = platform_get_drvdata(pdev);if (device_may_wakeup(&pdev->dev)) matrix_keypad_disable_wakeup(keypad);matrix_keypad_start(keypad->input_dev);return 0;}#endifstatic SIMPLE_DEV_PM_OPS(matrix_keypad_pm_ops, matrix_keypad_suspend, matrix_keypad_resume);/* 初始化矩阵按键GPIO，假设矩阵按键由 n行，m列 个GPIO组成 * 此函数先对 所有(m)列GPIO进行request申请，并且使用 gpio_derectout_output把所有(m)列GPIO * 端口设置成输出端，输出高电平，然后对所有行(n)GPIO进行request申请，并且使用gpio_derectout_input * 将GPIO设置成输入口，并且使用request_irq() 就所有(n)行GPIO设置为外部中断。 */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"); if (err) { dev_err(&pdev->dev, lia "failed to request GPIO%d for COL%d\n", pdata->col_gpios[i], i); goto err_free_cols; } gpio_direction_output(pdata->col_gpios[i], !pdata->active_low);}for (i = 0; i < pdata->num_row_gpios; i++) { err = gpio_request(pdata->row_gpios[i], "matrix_kbd_row"); if (err) { dev_err(&pdev->dev, "failed to request GPIO%d for ROW%d\n", pdata->row_gpios[i], i); goto err_free_rows; } gpio_direction_input(pdata->row_gpios[i]);}if (pdata->clustered_irq > 0) { err = request_irq(pdata->clustered_irq, matrix_keypad_interrupt, pdata->clustered_irq_flags, "matrix-keypad", keypad); if (err < 0) { dev_err(&pdev->dev, "Unable to acquire clustered interrupt\n"); goto err_free_rows; }} else { for (i = 0; i < pdata->num_row_gpios; i++) { err = request_threaded_irq( gpio_to_irq(pdata->row_gpios[i]), NULL, matrix_keypad_interrupt, IRQF_DISABLED | IRQF_ONESHOT | IRQF_TRIGGER_RISING | IRQF_TRIGGER_FALLING, "matrix-keypad", keypad); if (err < 0) { dev_err(&pdev->dev, "Unable to acquire interrupt for GPIO line %i\n", pdata->row_gpios[i]); goto err_free_irqs; } }}/* initialized as disabled - enabled by input->open */disable_row_irqs(keypad);return 0;err_free_irqs:while (--i >= 0) free_irq(gpio_to_irq(pdata->row_gpios[i]), keypad);i = pdata->num_row_gpios;err_free_rows:while (--i >= 0) gpio_free(pdata->row_gpios[i]);i = pdata->num_col_gpios;err_free_cols:while (--i >= 0) gpio_free(pdata->col_gpios[i]);return err;}//释放GPIOstatic void matrix_keypad_free_gpio(struct matrix_keypad *keypad){const struct matrix_keypad_platform_data *pdata = keypad->pdata;int i;if (pdata->clustered_irq > 0) { free_irq(pdata->clustered_irq, keypad);} else { for (i = 0; i < pdata->num_row_gpios; i++) free_irq(gpio_to_irq(pdata->row_gpios[i]), keypad);}for (i = 0; i < pdata->num_row_gpios; i++) gpio_free(pdata->row_gpios[i]);for (i = 0; i < pdata->num_col_gpios; i++) gpio_free(pdata->col_gpios[i]);}#ifdef CONFIG_OFstatic 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;if (!np) { dev_err(dev, "device lacks DT data\n"); return ERR_PTR(-ENODEV);}pdata = devm_kzalloc(dev, sizeof(*pdata), GFP_KERNEL);if (!pdata) { dev_err(dev, "could not allocate memory for platform data\n"); return ERR_PTR(-ENOMEM);}pdata->num_row_gpios = nrow = of_gpio_named_count(np, "row-gpios");pdata->num_col_gpios = ncol = of_gpio_named_count(np, "col-gpios");if (nrow <= 0 || ncol <= 0) { dev_err(dev, "number of keypad rows/columns not specified\n"); return ERR_PTR(-EINVAL);}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);of_property_read_u32(np, "col-scan-delay-us", &pdata->col_scan_delay_us);gpios = devm_kzalloc(dev, sizeof(unsigned int) * (pdata->num_row_gpios + pdata->num_col_gpios), GFP_KERNEL);if (!gpios) { dev_err(dev, "could not allocate memory for gpios\n"); return ERR_PTR(-ENOMEM);}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);pdata->row_gpios = gpios;pdata->col_gpios = &gpios[pdata->num_row_gpios];return pdata;}#elsestatic inline struct matrix_keypad_platform_data *matrix_keypad_parse_dt(struct device *dev){dev_err(dev, "no platform data defined\n");return ERR_PTR(-EINVAL);}#endifstatic int matrix_keypad_probe(struct platform_device *pdev){ //平台提供的 platform_dataconst struct matrix_keypad_platform_data *pdata; struct matrix_keypad *keypad;//输入设备结构体struct input_dev *input_dev; int err;//获取 platform_device->device->device_private.driver_data 平台设备私有数据pdata = dev_get_platdata(&pdev->dev);if (!pdata) { pdata = matrix_keypad_parse_dt(&pdev->dev); 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;}//申请 keypad 按键设备结构体，可以将指针保存到 platform_device->device->device_private.driver_data //作为平台设备的私有指针keypad = kzalloc(sizeof(struct matrix_keypad), GFP_KERNEL);//将会分配一个 input_dev 设备结构体，并且在 /sys/class/input/input-n 下创建设备属性文件input_dev = input_allocate_device();if (!keypad || !input_dev) { err = -ENOMEM; goto err_free_mem;}//设置 keypad 结构体keypad->input_dev = input_dev; //初始化 矩阵按键 input_dev 结构体 为当前申请的input_devkeypad->pdata = pdata;keypad->row_shift = get_count_order(pdata->num_col_gpios);keypad->stopped = true;//初始化 延时工作队列INIT_DELAYED_WORK(&keypad->work, matrix_keypad_scan);//初始化互斥体mutex_init(&keypad->lock);//初始化 input 输入设备结构体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;//从 keymap_data 里面分解出行列键对应的码值err = matrix_keypad_build_keymap(pdata->keymap_data, NULL, pdata->num_row_gpios, pdata->num_col_gpios, NULL, input_dev);if (err) { dev_err(&pdev->dev, "failed to build keymap\n"); goto err_free_mem;}if (!pdata->no_autorepeat) __set_bit(EV_REP, input_dev->evbit);input_set_capability(input_dev, EV_MSC, MSC_SCAN);//保存 keypad 矩阵按键指针 到 inputinput_set_drvdata(input_dev, keypad);/* 初始化矩阵按键GPIO，假设矩阵按键由 n行，m列 个GPIO组成 * 此函数先对 所有(m)列GPIO进行request申请，并且使用 gpio_derectout_output把所有(m)列GPIO * 端口设置成输出端，输出高电平，然后对所有行(n)GPIO进行request申请，并且使用gpio_derectout_input * 将GPIO设置成输入口，并且使用request_irq() 就所有(n)行GPIO设置为外部中断。 */err = matrix_keypad_init_gpio(pdev, keypad);if (err) goto err_free_mem;//注册 input输入设备err = input_register_device(keypad->input_dev);if (err) goto err_free_gpio;device_init_wakeup(&pdev->dev, pdata->wakeup);//将 keypad矩阵按键指针 保存到 platform_device->device->device_private.driver_data 作为平台设备私有成员platform_set_drvdata(pdev, keypad);return 0;err_free_gpio:matrix_keypad_free_gpio(keypad);err_free_mem:input_free_device(input_dev);kfree(keypad);return err;}static int matrix_keypad_remove(struct platform_device *pdev){/* platform_get_drvdata()用于调用 设备的局部（私有）变量 * 该局部变量是 platform_set_drvdata()函数 保存到 * platform_device->device->device_private.driver_data 变成设备私有数据 * * */struct matrix_keypad *keypad = platform_get_drvdata(pdev);device_init_wakeup(&pdev->dev, 0);matrix_keypad_free_gpio(keypad);mutex_destroy(&keypad->lock);//注销input输入设备input_unregister_device(keypad->input_dev);//释放 platform_get_drvdata/platform_set_drvdata 函数所操作的指针所指内存kfree(keypad);//platform_set_drvdata()用于保存局部变量，最终将 data 赋值给 platform_device->device->device_private.driver_data//将设备 保存的局部变量（私有数据）清零platform_set_drvdata(pdev, NULL);return 0; }
#ifdef CONFIG_OFstatic const struct of_device_id matrix_keypad_dt_match[] = {{ .compatible = "gpio-matrix-keypad" },{ }};MODULE_DEVICE_TABLE(of, matrix_keypad_dt_match);#endifstatic struct platform_driver matrix_keypad_driver = {.probe = matrix_keypad_probe,.remove = matrix_keypad_remove,.driver = { .name = "matrix-keypad", .owner = THIS_MODULE, .pm = &matrix_keypad_pm_ops, .of_match_table = of_match_ptr(matrix_keypad_dt_match),},};module_platform_driver(matrix_keypad_driver);//注册 矩阵按键驱动 为平台设备MODULE_AUTHOR("Marek Vasut ");MODULE_DESCRIPTION("GPIO Driven Matrix Keypad Driver");MODULE_LICENSE("GPL v2");MODULE_ALIAS("platform:matrix-keypad"); 设备树： 高高字节用于存储行号，高低字节用于存储列号，低高和低低字节用于保存值 matrix_keypad: matrix_keypad@0 { compatible = "gpio-matrix-keypad"; debounce-delay-ms = <50>; col-scan-delay-us = <5000>; pinctrl-names = "tlmm_gpio_key_active","tlmm_gpio_key_suspend"; pinctrl-0 = <&gpio_key_active>; pinctrl-1 = <&gpio_key_suspend>; row-gpios = <&msm_gpio 9 0 &msm_gpio 11 0 &msm_gpio 94 0 &msm_gpio 95 0 &msm_gpio 22 0>; col-gpios = <&msm_gpio 91 0 &msm_gpio 92 0 &msm_gpio 98 0 &msm_gpio 97 0>; linux,keymap = <0x00000004 /* (0,0) KEY_3 */ 0x00010007 /* (1,0) KEY_6 */ 0x0002000a /* (2,0) KEY_9 */ 0x0003020b /* (3,0) KEY_NUMERIC_POUND */ 0x01000003 /* (0,1) KEY_2 */ 0x01010006 /* (1,1) KEY_5 */ 0x01020009 /* (2,1) KEY_8 */ 0x0103000b /* (3,1) KEY_0 */ 0x02000002 /* (0,2) KEY_1 */ 0x02010005 /* (1,2) KEY_4 */ 0x02020008 /* (2,2) KEY_7 */ 0x0203020a /* (3,2) KEY_NUMERIC_STAR */ 0x0300009e /* (0,3) KEY_BACK */ 0x0301007f /* (1,3) KEY_MENU */ 0x0302001c /* (2,3) KEY_OK */ 0x0303006a /* (3,3) KEY_RIGHT */ 0x040000a9 /* (0,4) KEY_DIAL */ 0x04010069 /* (1,4) KEY_LEFT */ 0x04020067 /* (2,4) KEY_up */ 0x0403006c>; /* (3,4) KEY_down */ }; 调试命令：cat /proc/bus/input/devices 查看输入设备//hexdump命令一般用来查看“二进制”文件的十六进制编码，但实际上它能查看任何文件，而不只限于二进制文件busybox hexdump /dev/input/event0 ---按 按键查看按键扫描码/system/usr/keylayout/qwerty.kl 查看按键映射getevent -l /dev/input/event7 event7是触摸屏的input设备 ：格式是event type、event code、event value，至于这些所代表的含义可以参考input设备相关的东西。getevent：查看有多少输入子系统getevent -l /dev/input/event0 查看event0事件（msm8909 是矩阵按键事件）//最常用 调试总结：一般先确认设备树中按键码值正确，再排除引脚复用即可；引脚复用先检查kernel 再检查bootloader今天终于把手机矩阵按键彻底调通了，经历了近半个月，中间现象调试历程如下：第一阶段：按键没反映 ：解决方式：修改设备树中 按键码 第二阶段：个别按键有问题，现象是 2 5 8 0 这一列按键无论按下哪一个 都是全部反应，比如按下 2 ，那么 2 5 8 0 全部都会上报 ：解决方式：在kernel中找到了 矩阵按键的引脚复用，注释之第三阶段：2 5 8 0 这一列按键 偶尔会出现 第二阶段问题， 解决方式：通过打印按键引脚 发现这一列按键的 列中断引脚gpio11在开机的时候有异常，其他引脚都是默认低电平，只有这个引脚是默认高，说明有一个地方把它复用并且拉高了，排除kernel 那就剩下bootloader了，在bootloader中搜索关键字 “11” ，没错。你没有看错，就是搜索11，搜索出非常非常非常多的代码。。。，一个一个的看。要说明的是：如果真的是 在kernel bootloader中都没有复用的话，接下来的解决方式就是 看内核log,把所有的error都解决了也许冲突就解决了还有一种方式是 裁剪 XXX_defconfig文件。前提是你对配置文件比较熟悉。以上。
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