drivers/input/serio/ams_delta_serio.c

   1 /*
   2  *  Amstrad E3 (Delta) keyboard port driver
   3  *
   4  *  Copyright (c) 2006 Matt Callow
   5  *  Copyright (c) 2010 Janusz Krzysztofik
   6  *
   7  * This program is free software; you can redistribute it and/or modify it
   8  * under the terms of the GNU General Public License version 2 as published by
   9  * the Free Software Foundation.
  10  *
  11  * Thanks to Cliff Lawson for his help
  12  *
  13  * The Amstrad Delta keyboard (aka mailboard) uses normal PC-AT style serial
  14  * transmission.  The keyboard port is formed of two GPIO lines, for clock
  15  * and data.  Due to strict timing requirements of the interface,
  16  * the serial data stream is read and processed by a FIQ handler.
  17  * The resulting words are fetched by this driver from a circular buffer.
  18  *
  19  * Standard AT keyboard driver (atkbd) is used for handling the keyboard data.
  20  * However, when used with the E3 mailboard that producecs non-standard
  21  * scancodes, a custom key table must be prepared and loaded from userspace.
  22  */
  23 #include <linux/gpio.h>
  24 #include <linux/irq.h>
  25 #include <linux/serio.h>
  26 #include <linux/slab.h>
  27 #include <linux/module.h>
  28
  29 #include <asm/mach-types.h>
  30 #include <plat/board-ams-delta.h>
  31
  32 #include <mach/ams-delta-fiq.h>
  33
  34 MODULE_AUTHOR("Matt Callow");
  35 MODULE_DESCRIPTION("AMS Delta (E3) keyboard port driver");
  36 MODULE_LICENSE("GPL");
  37
  38 static struct serio *ams_delta_serio;
  39
  40 static int check_data(int data)
  41 {
  42         int i, parity = 0;
  43
  44         /* check valid stop bit */
  45         if (!(data & 0x400)) {
  46                 dev_warn(&ams_delta_serio->dev,
  47                                 "invalid stop bit, data=0x%X\n",
  48                                 data);
  49                 return SERIO_FRAME;
  50         }
  51         /* calculate the parity */
  52         for (i = 1; i < 10; i++) {
  53                 if (data & (1 << i))
  54                         parity++;
  55         }
  56         /* it should be odd */
  57         if (!(parity & 0x01)) {
  58                 dev_warn(&ams_delta_serio->dev,
  59                                 "paritiy check failed, data=0x%X parity=0x%X\n",
  60                                 data, parity);
  61                 return SERIO_PARITY;
  62         }
  63         return 0;
  64 }
  65
  66 static irqreturn_t ams_delta_serio_interrupt(int irq, void *dev_id)
  67 {
  68         int *circ_buff = &fiq_buffer[FIQ_CIRC_BUFF];
  69         int data, dfl;
  70         u8 scancode;
  71
  72         fiq_buffer[FIQ_IRQ_PEND] = 0;
  73
  74         /*
  75          * Read data from the circular buffer, check it
  76          * and then pass it on the serio
  77          */
  78         while (fiq_buffer[FIQ_KEYS_CNT] > 0) {
  79
  80                 data = circ_buff[fiq_buffer[FIQ_HEAD_OFFSET]++];
  81                 fiq_buffer[FIQ_KEYS_CNT]--;
  82                 if (fiq_buffer[FIQ_HEAD_OFFSET] == fiq_buffer[FIQ_BUF_LEN])
  83                         fiq_buffer[FIQ_HEAD_OFFSET] = 0;
  84
  85                 dfl = check_data(data);
  86                 scancode = (u8) (data >> 1) & 0xFF;
  87                 serio_interrupt(ams_delta_serio, scancode, dfl);
  88         }
  89         return IRQ_HANDLED;
  90 }
  91
  92 static int ams_delta_serio_open(struct serio *serio)
  93 {
  94         /* enable keyboard */
  95         gpio_set_value(AMS_DELTA_GPIO_PIN_KEYBRD_PWR, 1);
  96
  97         return 0;
  98 }
  99
 100 static void ams_delta_serio_close(struct serio *serio)
 101 {
 102         /* disable keyboard */
 103         gpio_set_value(AMS_DELTA_GPIO_PIN_KEYBRD_PWR, 0);
 104 }
 105
 106 static const struct gpio ams_delta_gpios[] __initconst_or_module = {
 107         {
 108                 .gpio   = AMS_DELTA_GPIO_PIN_KEYBRD_DATA,
 109                 .flags  = GPIOF_DIR_IN,
 110                 .label  = "serio-data",
 111         },
 112         {
 113                 .gpio   = AMS_DELTA_GPIO_PIN_KEYBRD_CLK,
 114                 .flags  = GPIOF_DIR_IN,
 115                 .label  = "serio-clock",
 116         },
 117         {
 118                 .gpio   = AMS_DELTA_GPIO_PIN_KEYBRD_PWR,
 119                 .flags  = GPIOF_OUT_INIT_LOW,
 120                 .label  = "serio-power",
 121         },
 122         {
 123                 .gpio   = AMS_DELTA_GPIO_PIN_KEYBRD_DATAOUT,
 124                 .flags  = GPIOF_OUT_INIT_LOW,
 125                 .label  = "serio-dataout",
 126         },
 127 };
 128
 129 static int __init ams_delta_serio_init(void)
 130 {
 131         int err;
 132
 133         if (!machine_is_ams_delta())
 134                 return -ENODEV;
 135
 136         ams_delta_serio = kzalloc(sizeof(struct serio), GFP_KERNEL);
 137         if (!ams_delta_serio)
 138                 return -ENOMEM;
 139
 140         ams_delta_serio->id.type = SERIO_8042;
 141         ams_delta_serio->open = ams_delta_serio_open;
 142         ams_delta_serio->close = ams_delta_serio_close;
 143         strlcpy(ams_delta_serio->name, "AMS DELTA keyboard adapter",
 144                         sizeof(ams_delta_serio->name));
 145         strlcpy(ams_delta_serio->phys, "GPIO/serio0",
 146                         sizeof(ams_delta_serio->phys));
 147
 148         err = gpio_request_array(ams_delta_gpios,
 149                                 ARRAY_SIZE(ams_delta_gpios));
 150         if (err) {
 151                 pr_err("ams_delta_serio: Couldn't request gpio pins\n");
 152                 goto serio;
 153         }
 154
 155         err = request_irq(gpio_to_irq(AMS_DELTA_GPIO_PIN_KEYBRD_CLK),
 156                         ams_delta_serio_interrupt, IRQ_TYPE_EDGE_RISING,
 157                         "ams-delta-serio", 0);
 158         if (err < 0) {
 159                 pr_err("ams_delta_serio: couldn't request gpio interrupt %d\n",
 160                                 gpio_to_irq(AMS_DELTA_GPIO_PIN_KEYBRD_CLK));
 161                 goto gpio;
 162         }
 163         /*
 164          * Since GPIO register handling for keyboard clock pin is performed
 165          * at FIQ level, switch back from edge to simple interrupt handler
 166          * to avoid bad interaction.
 167          */
 168         irq_set_handler(gpio_to_irq(AMS_DELTA_GPIO_PIN_KEYBRD_CLK),
 169                         handle_simple_irq);
 170
 171         serio_register_port(ams_delta_serio);
 172         dev_info(&ams_delta_serio->dev, "%s\n", ams_delta_serio->name);
 173
 174         return 0;
 175 gpio:
 176         gpio_free_array(ams_delta_gpios,
 177                         ARRAY_SIZE(ams_delta_gpios));
 178 serio:
 179         kfree(ams_delta_serio);
 180         return err;
 181 }
 182 module_init(ams_delta_serio_init);
 183
 184 static void __exit ams_delta_serio_exit(void)
 185 {
 186         serio_unregister_port(ams_delta_serio);
 187         free_irq(gpio_to_irq(AMS_DELTA_GPIO_PIN_KEYBRD_CLK), 0);
 188         gpio_free_array(ams_delta_gpios,
 189                         ARRAY_SIZE(ams_delta_gpios));
 190 }
 191 module_exit(ams_delta_serio_exit);