1 // SPDX-License-Identifier: GPL-2.0-only 2 /* 3 * Support for the S1 button on Routerboard 532 4 * 5 * Copyright (C) 2009 Phil Sutter <n0-1@freewrt.org> 6 */ 7 8 #include <linux/input-polldev.h> 9 #include <linux/module.h> 10 #include <linux/platform_device.h> 11 #include <linux/gpio.h> 12 13 #include <asm/mach-rc32434/gpio.h> 14 #include <asm/mach-rc32434/rb.h> 15 16 #define DRV_NAME "rb532-button" 17 18 #define RB532_BTN_RATE 100 /* msec */ 19 #define RB532_BTN_KSYM BTN_0 20 21 /* The S1 button state is provided by GPIO pin 1. But as this 22 * pin is also used for uart input as alternate function, the 23 * operational modes must be switched first: 24 * 1) disable uart using set_latch_u5() 25 * 2) turn off alternate function implicitly through 26 * gpio_direction_input() 27 * 3) read the GPIO's current value 28 * 4) undo step 2 by enabling alternate function (in this 29 * mode the GPIO direction is fixed, so no change needed) 30 * 5) turn on uart again 31 * The GPIO value occurs to be inverted, so pin high means 32 * button is not pressed. 33 */ 34 static bool rb532_button_pressed(void) 35 { 36 int val; 37 38 set_latch_u5(0, LO_FOFF); 39 gpio_direction_input(GPIO_BTN_S1); 40 41 val = gpio_get_value(GPIO_BTN_S1); 42 43 rb532_gpio_set_func(GPIO_BTN_S1); 44 set_latch_u5(LO_FOFF, 0); 45 46 return !val; 47 } 48 49 static void rb532_button_poll(struct input_polled_dev *poll_dev) 50 { 51 input_report_key(poll_dev->input, RB532_BTN_KSYM, 52 rb532_button_pressed()); 53 input_sync(poll_dev->input); 54 } 55 56 static int rb532_button_probe(struct platform_device *pdev) 57 { 58 struct input_polled_dev *poll_dev; 59 int error; 60 61 poll_dev = input_allocate_polled_device(); 62 if (!poll_dev) 63 return -ENOMEM; 64 65 poll_dev->poll = rb532_button_poll; 66 poll_dev->poll_interval = RB532_BTN_RATE; 67 68 poll_dev->input->name = "rb532 button"; 69 poll_dev->input->phys = "rb532/button0"; 70 poll_dev->input->id.bustype = BUS_HOST; 71 poll_dev->input->dev.parent = &pdev->dev; 72 73 dev_set_drvdata(&pdev->dev, poll_dev); 74 75 input_set_capability(poll_dev->input, EV_KEY, RB532_BTN_KSYM); 76 77 error = input_register_polled_device(poll_dev); 78 if (error) { 79 input_free_polled_device(poll_dev); 80 return error; 81 } 82 83 return 0; 84 } 85 86 static int rb532_button_remove(struct platform_device *pdev) 87 { 88 struct input_polled_dev *poll_dev = dev_get_drvdata(&pdev->dev); 89 90 input_unregister_polled_device(poll_dev); 91 input_free_polled_device(poll_dev); 92 93 return 0; 94 } 95 96 static struct platform_driver rb532_button_driver = { 97 .probe = rb532_button_probe, 98 .remove = rb532_button_remove, 99 .driver = { 100 .name = DRV_NAME, 101 }, 102 }; 103 module_platform_driver(rb532_button_driver); 104 105 MODULE_AUTHOR("Phil Sutter <n0-1@freewrt.org>"); 106 MODULE_LICENSE("GPL"); 107 MODULE_DESCRIPTION("Support for S1 button on Routerboard 532"); 108 MODULE_ALIAS("platform:" DRV_NAME); 109