drivers/char/pc8736x_gpio.c

   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
  28 MODULE_AUTHOR("Jim Cromie <jim.cromie@gmail.com>");
  29 MODULE_DESCRIPTION("NatSemi/Winbond PC-8736x GPIO Pin Driver");
  30 MODULE_LICENSE("GPL");
  31
  32 static int major;               /* default to dynamic major */
  33 module_param(major, int, 0);
  34 MODULE_PARM_DESC(major, "Major device number");
  35
  36 static DEFINE_MUTEX(pc8736x_gpio_config_lock);
  37 static unsigned pc8736x_gpio_base;
  38 static 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
  67 static unsigned char superio_cmd = 0;
  68 static unsigned char selected_device = 0xFF;    /* bogus start val */
  69
  70 /* GPIO port runtime access, functionality */
  71 static 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
  79 static struct platform_device *pdev;  /* use in dev_*() */
  80
  81 static inline void superio_outb(int addr, int val)
  82 {
  83         outb_p(addr, superio_cmd);
  84         outb_p(val, superio_cmd + 1);
  85 }
  86
  87 static inline int superio_inb(int addr)
  88 {
  89         outb_p(addr, superio_cmd);
  90         return inb_p(superio_cmd + 1);
  91 }
  92
  93 static 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
 111 static void device_select(unsigned devldn)
 112 {
 113         superio_outb(SIO_UNIT_SEL, devldn);
 114         selected_device = devldn;
 115 }
 116
 117 static 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
 125 static 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
 147 static 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
 153 static 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
 170 static 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
 197 static 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
 206 static void pc8736x_gpio_change(unsigned index)
 207 {
 208         pc8736x_gpio_set(index, !pc8736x_gpio_current(index));
 209 }
 210
 211 static 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
 221 static 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
 233 static 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
 241 static 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
 253 static struct cdev pc8736x_gpio_cdev;
 254
 255 static 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
 331 undo_request_region:
 332         release_region(pc8736x_gpio_base, PC8736X_GPIO_RANGE);
 333 undo_platform_dev_add:
 334         platform_device_del(pdev);
 335 undo_platform_dev_alloc:
 336         platform_device_put(pdev);
 337
 338         return rc;
 339 }
 340
 341 static 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
 352 module_init(pc8736x_gpio_init);
 353 module_exit(pc8736x_gpio_cleanup);