linux/drivers/char/pc8736x_gpio.c
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   1// SPDX-License-Identifier: GPL-2.0-only
   2/* linux/drivers/char/pc8736x_gpio.c
   3
   4   National Semiconductor PC8736x GPIO driver.  Allows a user space
   5   process to play with the GPIO pins.
   6
   7   Copyright (c) 2005,2006 Jim Cromie <jim.cromie@gmail.com>
   8
   9   adapted from linux/drivers/char/scx200_gpio.c
  10   Copyright (c) 2001,2002 Christer Weinigel <wingel@nano-system.com>,
  11*/
  12
  13#include <linux/fs.h>
  14#include <linux/module.h>
  15#include <linux/errno.h>
  16#include <linux/kernel.h>
  17#include <linux/init.h>
  18#include <linux/cdev.h>
  19#include <linux/io.h>
  20#include <linux/ioport.h>
  21#include <linux/mutex.h>
  22#include <linux/nsc_gpio.h>
  23#include <linux/platform_device.h>
  24#include <linux/uaccess.h>
  25
  26#define DEVNAME "pc8736x_gpio"
  27
  28MODULE_AUTHOR("Jim Cromie <jim.cromie@gmail.com>");
  29MODULE_DESCRIPTION("NatSemi/Winbond PC-8736x GPIO Pin Driver");
  30MODULE_LICENSE("GPL");
  31
  32static int major;               /* default to dynamic major */
  33module_param(major, int, 0);
  34MODULE_PARM_DESC(major, "Major device number");
  35
  36static DEFINE_MUTEX(pc8736x_gpio_config_lock);
  37static unsigned pc8736x_gpio_base;
  38static u8 pc8736x_gpio_shadow[4];
  39
  40#define SIO_BASE1       0x2E    /* 1st command-reg to check */
  41#define SIO_BASE2       0x4E    /* alt command-reg to check */
  42
  43#define SIO_SID         0x20    /* SuperI/O ID Register */
  44#define SIO_SID_PC87365 0xe5    /* Expected value in ID Register for PC87365 */
  45#define SIO_SID_PC87366 0xe9    /* Expected value in ID Register for PC87366 */
  46
  47#define SIO_CF1         0x21    /* chip config, bit0 is chip enable */
  48
  49#define PC8736X_GPIO_RANGE      16 /* ioaddr range */
  50#define PC8736X_GPIO_CT         32 /* minors matching 4 8 bit ports */
  51
  52#define SIO_UNIT_SEL    0x7     /* unit select reg */
  53#define SIO_UNIT_ACT    0x30    /* unit enable */
  54#define SIO_GPIO_UNIT   0x7     /* unit number of GPIO */
  55#define SIO_VLM_UNIT    0x0D
  56#define SIO_TMS_UNIT    0x0E
  57
  58/* config-space addrs to read/write each unit's runtime addr */
  59#define SIO_BASE_HADDR          0x60
  60#define SIO_BASE_LADDR          0x61
  61
  62/* GPIO config-space pin-control addresses */
  63#define SIO_GPIO_PIN_SELECT     0xF0
  64#define SIO_GPIO_PIN_CONFIG     0xF1
  65#define SIO_GPIO_PIN_EVENT      0xF2
  66
  67static unsigned char superio_cmd = 0;
  68static unsigned char selected_device = 0xFF;    /* bogus start val */
  69
  70/* GPIO port runtime access, functionality */
  71static int port_offset[] = { 0, 4, 8, 10 };     /* non-uniform offsets ! */
  72/* static int event_capable[] = { 1, 1, 0, 0 };   ports 2,3 are hobbled */
  73
  74#define PORT_OUT        0
  75#define PORT_IN         1
  76#define PORT_EVT_EN     2
  77#define PORT_EVT_STST   3
  78
  79static struct platform_device *pdev;  /* use in dev_*() */
  80
  81static inline void superio_outb(int addr, int val)
  82{
  83        outb_p(addr, superio_cmd);
  84        outb_p(val, superio_cmd + 1);
  85}
  86
  87static inline int superio_inb(int addr)
  88{
  89        outb_p(addr, superio_cmd);
  90        return inb_p(superio_cmd + 1);
  91}
  92
  93static int pc8736x_superio_present(void)
  94{
  95        int id;
  96
  97        /* try the 2 possible values, read a hardware reg to verify */
  98        superio_cmd = SIO_BASE1;
  99        id = superio_inb(SIO_SID);
 100        if (id == SIO_SID_PC87365 || id == SIO_SID_PC87366)
 101                return superio_cmd;
 102
 103        superio_cmd = SIO_BASE2;
 104        id = superio_inb(SIO_SID);
 105        if (id == SIO_SID_PC87365 || id == SIO_SID_PC87366)
 106                return superio_cmd;
 107
 108        return 0;
 109}
 110
 111static void device_select(unsigned devldn)
 112{
 113        superio_outb(SIO_UNIT_SEL, devldn);
 114        selected_device = devldn;
 115}
 116
 117static void select_pin(unsigned iminor)
 118{
 119        /* select GPIO port/pin from device minor number */
 120        device_select(SIO_GPIO_UNIT);
 121        superio_outb(SIO_GPIO_PIN_SELECT,
 122                     ((iminor << 1) & 0xF0) | (iminor & 0x7));
 123}
 124
 125static inline u32 pc8736x_gpio_configure_fn(unsigned index, u32 mask, u32 bits,
 126                                            u32 func_slct)
 127{
 128        u32 config, new_config;
 129
 130        mutex_lock(&pc8736x_gpio_config_lock);
 131
 132        device_select(SIO_GPIO_UNIT);
 133        select_pin(index);
 134
 135        /* read current config value */
 136        config = superio_inb(func_slct);
 137
 138        /* set new config */
 139        new_config = (config & mask) | bits;
 140        superio_outb(func_slct, new_config);
 141
 142        mutex_unlock(&pc8736x_gpio_config_lock);
 143
 144        return config;
 145}
 146
 147static u32 pc8736x_gpio_configure(unsigned index, u32 mask, u32 bits)
 148{
 149        return pc8736x_gpio_configure_fn(index, mask, bits,
 150                                         SIO_GPIO_PIN_CONFIG);
 151}
 152
 153static int pc8736x_gpio_get(unsigned minor)
 154{
 155        int port, bit, val;
 156
 157        port = minor >> 3;
 158        bit = minor & 7;
 159        val = inb_p(pc8736x_gpio_base + port_offset[port] + PORT_IN);
 160        val >>= bit;
 161        val &= 1;
 162
 163        dev_dbg(&pdev->dev, "_gpio_get(%d from %x bit %d) == val %d\n",
 164                minor, pc8736x_gpio_base + port_offset[port] + PORT_IN, bit,
 165                val);
 166
 167        return val;
 168}
 169
 170static void pc8736x_gpio_set(unsigned minor, int val)
 171{
 172        int port, bit, curval;
 173
 174        minor &= 0x1f;
 175        port = minor >> 3;
 176        bit = minor & 7;
 177        curval = inb_p(pc8736x_gpio_base + port_offset[port] + PORT_OUT);
 178
 179        dev_dbg(&pdev->dev, "addr:%x cur:%x bit-pos:%d cur-bit:%x + new:%d -> bit-new:%d\n",
 180                pc8736x_gpio_base + port_offset[port] + PORT_OUT,
 181                curval, bit, (curval & ~(1 << bit)), val, (val << bit));
 182
 183        val = (curval & ~(1 << bit)) | (val << bit);
 184
 185        dev_dbg(&pdev->dev, "gpio_set(minor:%d port:%d bit:%d)"
 186                " %2x -> %2x\n", minor, port, bit, curval, val);
 187
 188        outb_p(val, pc8736x_gpio_base + port_offset[port] + PORT_OUT);
 189
 190        curval = inb_p(pc8736x_gpio_base + port_offset[port] + PORT_OUT);
 191        val = inb_p(pc8736x_gpio_base + port_offset[port] + PORT_IN);
 192
 193        dev_dbg(&pdev->dev, "wrote %x, read: %x\n", curval, val);
 194        pc8736x_gpio_shadow[port] = val;
 195}
 196
 197static int pc8736x_gpio_current(unsigned minor)
 198{
 199        int port, bit;
 200        minor &= 0x1f;
 201        port = minor >> 3;
 202        bit = minor & 7;
 203        return ((pc8736x_gpio_shadow[port] >> bit) & 0x01);
 204}
 205
 206static void pc8736x_gpio_change(unsigned index)
 207{
 208        pc8736x_gpio_set(index, !pc8736x_gpio_current(index));
 209}
 210
 211static struct nsc_gpio_ops pc8736x_gpio_ops = {
 212        .owner          = THIS_MODULE,
 213        .gpio_config    = pc8736x_gpio_configure,
 214        .gpio_dump      = nsc_gpio_dump,
 215        .gpio_get       = pc8736x_gpio_get,
 216        .gpio_set       = pc8736x_gpio_set,
 217        .gpio_change    = pc8736x_gpio_change,
 218        .gpio_current   = pc8736x_gpio_current
 219};
 220
 221static int pc8736x_gpio_open(struct inode *inode, struct file *file)
 222{
 223        unsigned m = iminor(inode);
 224        file->private_data = &pc8736x_gpio_ops;
 225
 226        dev_dbg(&pdev->dev, "open %d\n", m);
 227
 228        if (m >= PC8736X_GPIO_CT)
 229                return -EINVAL;
 230        return nonseekable_open(inode, file);
 231}
 232
 233static const struct file_operations pc8736x_gpio_fileops = {
 234        .owner  = THIS_MODULE,
 235        .open   = pc8736x_gpio_open,
 236        .write  = nsc_gpio_write,
 237        .read   = nsc_gpio_read,
 238        .llseek = no_llseek,
 239};
 240
 241static void __init pc8736x_init_shadow(void)
 242{
 243        int port;
 244
 245        /* read the current values driven on the GPIO signals */
 246        for (port = 0; port < 4; ++port)
 247                pc8736x_gpio_shadow[port]
 248                    = inb_p(pc8736x_gpio_base + port_offset[port]
 249                            + PORT_OUT);
 250
 251}
 252
 253static struct cdev pc8736x_gpio_cdev;
 254
 255static int __init pc8736x_gpio_init(void)
 256{
 257        int rc;
 258        dev_t devid;
 259
 260        pdev = platform_device_alloc(DEVNAME, 0);
 261        if (!pdev)
 262                return -ENOMEM;
 263
 264        rc = platform_device_add(pdev);
 265        if (rc) {
 266                rc = -ENODEV;
 267                goto undo_platform_dev_alloc;
 268        }
 269        dev_info(&pdev->dev, "NatSemi pc8736x GPIO Driver Initializing\n");
 270
 271        if (!pc8736x_superio_present()) {
 272                rc = -ENODEV;
 273                dev_err(&pdev->dev, "no device found\n");
 274                goto undo_platform_dev_add;
 275        }
 276        pc8736x_gpio_ops.dev = &pdev->dev;
 277
 278        /* Verify that chip and it's GPIO unit are both enabled.
 279           My BIOS does this, so I take minimum action here
 280         */
 281        rc = superio_inb(SIO_CF1);
 282        if (!(rc & 0x01)) {
 283                rc = -ENODEV;
 284                dev_err(&pdev->dev, "device not enabled\n");
 285                goto undo_platform_dev_add;
 286        }
 287        device_select(SIO_GPIO_UNIT);
 288        if (!superio_inb(SIO_UNIT_ACT)) {
 289                rc = -ENODEV;
 290                dev_err(&pdev->dev, "GPIO unit not enabled\n");
 291                goto undo_platform_dev_add;
 292        }
 293
 294        /* read the GPIO unit base addr that chip responds to */
 295        pc8736x_gpio_base = (superio_inb(SIO_BASE_HADDR) << 8
 296                             | superio_inb(SIO_BASE_LADDR));
 297
 298        if (!request_region(pc8736x_gpio_base, PC8736X_GPIO_RANGE, DEVNAME)) {
 299                rc = -ENODEV;
 300                dev_err(&pdev->dev, "GPIO ioport %x busy\n",
 301                        pc8736x_gpio_base);
 302                goto undo_platform_dev_add;
 303        }
 304        dev_info(&pdev->dev, "GPIO ioport %x reserved\n", pc8736x_gpio_base);
 305
 306        if (major) {
 307                devid = MKDEV(major, 0);
 308                rc = register_chrdev_region(devid, PC8736X_GPIO_CT, DEVNAME);
 309        } else {
 310                rc = alloc_chrdev_region(&devid, 0, PC8736X_GPIO_CT, DEVNAME);
 311                major = MAJOR(devid);
 312        }
 313
 314        if (rc < 0) {
 315                dev_err(&pdev->dev, "register-chrdev failed: %d\n", rc);
 316                goto undo_request_region;
 317        }
 318        if (!major) {
 319                major = rc;
 320                dev_dbg(&pdev->dev, "got dynamic major %d\n", major);
 321        }
 322
 323        pc8736x_init_shadow();
 324
 325        /* ignore minor errs, and succeed */
 326        cdev_init(&pc8736x_gpio_cdev, &pc8736x_gpio_fileops);
 327        cdev_add(&pc8736x_gpio_cdev, devid, PC8736X_GPIO_CT);
 328
 329        return 0;
 330
 331undo_request_region:
 332        release_region(pc8736x_gpio_base, PC8736X_GPIO_RANGE);
 333undo_platform_dev_add:
 334        platform_device_del(pdev);
 335undo_platform_dev_alloc:
 336        platform_device_put(pdev);
 337
 338        return rc;
 339}
 340
 341static void __exit pc8736x_gpio_cleanup(void)
 342{
 343        dev_dbg(&pdev->dev, "cleanup\n");
 344
 345        cdev_del(&pc8736x_gpio_cdev);
 346        unregister_chrdev_region(MKDEV(major,0), PC8736X_GPIO_CT);
 347        release_region(pc8736x_gpio_base, PC8736X_GPIO_RANGE);
 348
 349        platform_device_unregister(pdev);
 350}
 351
 352module_init(pc8736x_gpio_init);
 353module_exit(pc8736x_gpio_cleanup);
 354