drivers/input/serio/ams_delta_serio.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  *  Amstrad E3 (Delta) keyboard port driver
   4  *
   5  *  Copyright (c) 2006 Matt Callow
   6  *  Copyright (c) 2010 Janusz Krzysztofik
   7  *
   8  * Thanks to Cliff Lawson for his help
   9  *
  10  * The Amstrad Delta keyboard (aka mailboard) uses normal PC-AT style serial
  11  * transmission.  The keyboard port is formed of two GPIO lines, for clock
  12  * and data.  Due to strict timing requirements of the interface,
  13  * the serial data stream is read and processed by a FIQ handler.
  14  * The resulting words are fetched by this driver from a circular buffer.
  15  *
  16  * Standard AT keyboard driver (atkbd) is used for handling the keyboard data.
  17  * However, when used with the E3 mailboard that producecs non-standard
  18  * scancodes, a custom key table must be prepared and loaded from userspace.
  19  */
  20 #include <linux/irq.h>
  21 #include <linux/platform_data/ams-delta-fiq.h>
  22 #include <linux/platform_device.h>
  23 #include <linux/regulator/consumer.h>
  24 #include <linux/serio.h>
  25 #include <linux/slab.h>
  26 #include <linux/module.h>
  27
  28 #define DRIVER_NAME     "ams-delta-serio"
  29
  30 MODULE_AUTHOR("Matt Callow");
  31 MODULE_DESCRIPTION("AMS Delta (E3) keyboard port driver");
  32 MODULE_LICENSE("GPL");
  33
  34 struct ams_delta_serio {
  35         struct serio *serio;
  36         struct regulator *vcc;
  37         unsigned int *fiq_buffer;
  38 };
  39
  40 static int check_data(struct serio *serio, int data)
  41 {
  42         int i, parity = 0;
  43
  44         /* check valid stop bit */
  45         if (!(data & 0x400)) {
  46                 dev_warn(&serio->dev, "invalid stop bit, data=0x%X\n", data);
  47                 return SERIO_FRAME;
  48         }
  49         /* calculate the parity */
  50         for (i = 1; i < 10; i++) {
  51                 if (data & (1 << i))
  52                         parity++;
  53         }
  54         /* it should be odd */
  55         if (!(parity & 0x01)) {
  56                 dev_warn(&serio->dev,
  57                          "parity check failed, data=0x%X parity=0x%X\n", data,
  58                          parity);
  59                 return SERIO_PARITY;
  60         }
  61         return 0;
  62 }
  63
  64 static irqreturn_t ams_delta_serio_interrupt(int irq, void *dev_id)
  65 {
  66         struct ams_delta_serio *priv = dev_id;
  67         int *circ_buff = &priv->fiq_buffer[FIQ_CIRC_BUFF];
  68         int data, dfl;
  69         u8 scancode;
  70
  71         priv->fiq_buffer[FIQ_IRQ_PEND] = 0;
  72
  73         /*
  74          * Read data from the circular buffer, check it
  75          * and then pass it on the serio
  76          */
  77         while (priv->fiq_buffer[FIQ_KEYS_CNT] > 0) {
  78
  79                 data = circ_buff[priv->fiq_buffer[FIQ_HEAD_OFFSET]++];
  80                 priv->fiq_buffer[FIQ_KEYS_CNT]--;
  81                 if (priv->fiq_buffer[FIQ_HEAD_OFFSET] ==
  82                     priv->fiq_buffer[FIQ_BUF_LEN])
  83                         priv->fiq_buffer[FIQ_HEAD_OFFSET] = 0;
  84
  85                 dfl = check_data(priv->serio, data);
  86                 scancode = (u8) (data >> 1) & 0xFF;
  87                 serio_interrupt(priv->serio, scancode, dfl);
  88         }
  89         return IRQ_HANDLED;
  90 }
  91
  92 static int ams_delta_serio_open(struct serio *serio)
  93 {
  94         struct ams_delta_serio *priv = serio->port_data;
  95
  96         /* enable keyboard */
  97         return regulator_enable(priv->vcc);
  98 }
  99
 100 static void ams_delta_serio_close(struct serio *serio)
 101 {
 102         struct ams_delta_serio *priv = serio->port_data;
 103
 104         /* disable keyboard */
 105         regulator_disable(priv->vcc);
 106 }
 107
 108 static int ams_delta_serio_init(struct platform_device *pdev)
 109 {
 110         struct ams_delta_serio *priv;
 111         struct serio *serio;
 112         int irq, err;
 113
 114         priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL);
 115         if (!priv)
 116                 return -ENOMEM;
 117
 118         priv->fiq_buffer = pdev->dev.platform_data;
 119         if (!priv->fiq_buffer)
 120                 return -EINVAL;
 121
 122         priv->vcc = devm_regulator_get(&pdev->dev, "vcc");
 123         if (IS_ERR(priv->vcc)) {
 124                 err = PTR_ERR(priv->vcc);
 125                 dev_err(&pdev->dev, "regulator request failed (%d)\n", err);
 126                 /*
 127                  * When running on a non-dt platform and requested regulator
 128                  * is not available, devm_regulator_get() never returns
 129                  * -EPROBE_DEFER as it is not able to justify if the regulator
 130                  * may still appear later.  On the other hand, the board can
 131                  * still set full constriants flag at late_initcall in order
 132                  * to instruct devm_regulator_get() to returnn a dummy one
 133                  * if sufficient.  Hence, if we get -ENODEV here, let's convert
 134                  * it to -EPROBE_DEFER and wait for the board to decide or
 135                  * let Deferred Probe infrastructure handle this error.
 136                  */
 137                 if (err == -ENODEV)
 138                         err = -EPROBE_DEFER;
 139                 return err;
 140         }
 141
 142         irq = platform_get_irq(pdev, 0);
 143         if (irq < 0)
 144                 return -ENXIO;
 145
 146         err = devm_request_irq(&pdev->dev, irq, ams_delta_serio_interrupt,
 147                                IRQ_TYPE_EDGE_RISING, DRIVER_NAME, priv);
 148         if (err < 0) {
 149                 dev_err(&pdev->dev, "IRQ request failed (%d)\n", err);
 150                 return err;
 151         }
 152
 153         serio = kzalloc(sizeof(*serio), GFP_KERNEL);
 154         if (!serio)
 155                 return -ENOMEM;
 156
 157         priv->serio = serio;
 158
 159         serio->id.type = SERIO_8042;
 160         serio->open = ams_delta_serio_open;
 161         serio->close = ams_delta_serio_close;
 162         strlcpy(serio->name, "AMS DELTA keyboard adapter", sizeof(serio->name));
 163         strlcpy(serio->phys, dev_name(&pdev->dev), sizeof(serio->phys));
 164         serio->dev.parent = &pdev->dev;
 165         serio->port_data = priv;
 166
 167         serio_register_port(serio);
 168
 169         platform_set_drvdata(pdev, priv);
 170
 171         dev_info(&serio->dev, "%s\n", serio->name);
 172
 173         return 0;
 174 }
 175
 176 static int ams_delta_serio_exit(struct platform_device *pdev)
 177 {
 178         struct ams_delta_serio *priv = platform_get_drvdata(pdev);
 179
 180         serio_unregister_port(priv->serio);
 181
 182         return 0;
 183 }
 184
 185 static struct platform_driver ams_delta_serio_driver = {
 186         .probe  = ams_delta_serio_init,
 187         .remove = ams_delta_serio_exit,
 188         .driver = {
 189                 .name   = DRIVER_NAME
 190         },
 191 };
 192 module_platform_driver(ams_delta_serio_driver);