atmel触摸屏驱动分析 · 荔枝派Zero指南

# atmel触摸屏驱动分析最新代码在：https://github.com/atmel-maxtouch/linux 3847行从下往上走读：版权信息 ~~~ /* Module information */ MODULE_AUTHOR("Joonyoung Shim <jy0922.shim@samsung.com>"); MODULE_DESCRIPTION("Atmel maXTouch Touchscreen driver"); MODULE_LICENSE("GPL"); ~~~ 设备树匹配的名称： ~~~ static const struct i2c_device_id mxt_id[] = { { "qt602240_ts", 0 }, { "atmel_mxt_ts", 0 }, { "atmel_mxt_tp", 0 }, { "maxtouch", 0 }, { "mXT224", 0 }, { } }; ~~~ 待机模式操作 `static SIMPLE_DEV_PM_OPS(mxt_pm_ops, mxt_suspend, mxt_resume);` ~~~ #define SIMPLE_DEV_PM_OPS(name, suspend_fn, resume_fn) \ const struct dev_pm_ops name = { \ SET_SYSTEM_SLEEP_PM_OPS(suspend_fn, resume_fn) \ } ~~~ 移除操作 ~~~ static int mxt_remove(struct i2c_client *client) { struct mxt_data *data = i2c_get_clientdata(client); sysfs_remove_group(&client->dev.kobj, &mxt_fw_attr_group); mxt_debug_msg_remove(data); mxt_sysfs_remove(data); #ifndef __POLL if (data->irq) free_irq(data->irq, data); #endif regulator_put(data->reg_avdd); regulator_put(data->reg_vdd); mxt_free_input_device(data); mxt_free_object_table(data); kfree(data); return 0; } ~~~ 插入操作 ~~~ static int mxt_probe(struct i2c_client *client, const struct i2c_device_id *id) { struct mxt_data *data; const struct mxt_platform_data *pdata; int error; pdata = mxt_get_platform_data(client); //获取平台数据 if (IS_ERR(pdata)) return PTR_ERR(pdata); data = kzalloc(sizeof(struct mxt_data), GFP_KERNEL); if (!data) return -ENOMEM; snprintf(data->phys, sizeof(data->phys), "i2c-%u-%04x/input0", client->adapter->nr, client->addr); data->client = client; data->pdata = pdata; i2c_set_clientdata(client, data); //保存数据 if (data->pdata->cfg_name) //配置文件名 mxt_update_file_name(&data->client->dev, &data->cfg_name, data->pdata->cfg_name, strlen(data->pdata->cfg_name)); init_completion(&data->chg_completion); init_completion(&data->reset_completion); init_completion(&data->crc_completion); mutex_init(&data->debug_msg_lock); if (pdata->suspend_mode == MXT_SUSPEND_REGULATOR) { __D; error = mxt_acquire_irq(data); if (error) goto err_free_mem; error = mxt_probe_regulators(data); if (error) goto err_free_irq; disable_irq(data->irq); } error = sysfs_create_group(&client->dev.kobj, &mxt_fw_attr_group); if (error) { dev_err(&client->dev, "Failure %d creating fw sysfs group\n", error); return error; } error = mxt_initialize(data); if (error) goto err_free_irq; return 0; err_free_irq: if (data->irq) free_irq(data->irq, data); err_free_mem: kfree(data); return error; } ~~~ 获取平台数据 ~~~ static const struct mxt_platform_data * mxt_get_platform_data(struct i2c_client *client) { const struct mxt_platform_data *pdata; pdata = dev_get_platdata(&client->dev); //已经获取过就直接返回 if (pdata) return pdata; pdata = mxt_parse_dt(client); //解析dts//初始化gpio_reset，cfg_name，input_name，gpio-keymap，suspend_mode if (!IS_ERR(pdata) || PTR_ERR(pdata) != -ENOENT) return pdata; pdata = mxt_parse_acpi(client); if (!IS_ERR(pdata) || PTR_ERR(pdata) != -ENOENT) return pdata; pdata = mxt_default_pdata(client); if (!IS_ERR(pdata)) return pdata; dev_err(&client->dev, "No platform data specified\n"); return ERR_PTR(-EINVAL); } ~~~ 获取中断 ~~~ static int mxt_acquire_irq(struct mxt_data *data) { int error; #ifndef __POLL if (!data->irq) { //没有中断的话申请中断线程 error = request_threaded_irq(data->client->irq, NULL, mxt_interrupt, data->pdata->irqflags | IRQF_ONESHOT, data->client->name, data); if (error) { dev_err(&data->client->dev, "Error requesting irq\n"); return error; } /* Presence of data->irq means IRQ initialised */ data->irq = data->client->irq; } else { //存在中断，则使能 enable_irq(data->irq); } #endif if (data->object_table && data->use_retrigen_workaround) { error = mxt_process_messages_until_invalid(data); if (error) return error; } return 0; } ~~~ 中断服务例程 ~~~ static irqreturn_t mxt_interrupt(int irq, void *dev_id) { struct mxt_data *data = dev_id; complete(&data->chg_completion); if (data->in_bootloader) { if (data->flash && &data->flash->work) cancel_delayed_work_sync(&data->flash->work); return IRQ_RETVAL(mxt_check_bootloader(data)); } if (!data->object_table) return IRQ_HANDLED; if (data->T44_address) { //有T44地址 return mxt_process_messages_t44(data); } else { return mxt_process_messages(data); } } ~~~ 处理消息 ~~~ static irqreturn_t mxt_process_messages(struct mxt_data *data) { int total_handled, num_handled; u8 count = data->last_message_count; if (count < 1 || count > data->max_reportid) count = 1; /* include final invalid message */ total_handled = mxt_read_and_process_messages(data, count + 1); if (total_handled < 0) return IRQ_NONE; /* if there were invalid messages, then we are done */ else if (total_handled <= count) goto update_count; /* keep reading two msgs until one is invalid or reportid limit */ do { num_handled = mxt_read_and_process_messages(data, 2); if (num_handled < 0) return IRQ_NONE; total_handled += num_handled; if (num_handled < 2) break; } while (total_handled < data->num_touchids); update_count: data->last_message_count = total_handled; if (data->update_input) { mxt_input_sync(data); data->update_input = false; } return IRQ_HANDLED; } ~~~