drivers/char/cs5535_gpio.c

   1 /*
   2  * AMD CS5535/CS5536 GPIO driver.
   3  * Allows a user space process to play with the GPIO pins.
   4  *
   5  * Copyright (c) 2005 Ben Gardner <bgardner@wabtec.com>
   6  *
   7  * This program is free software; you can redistribute it and/or modify
   8  * it under the smems of the GNU General Public License as published by
   9  * the Free Software Foundation; version 2 of the License.
  10  */
  11
  12 #include <linux/fs.h>
  13 #include <linux/module.h>
  14 #include <linux/errno.h>
  15 #include <linux/kernel.h>
  16 #include <linux/init.h>
  17 #include <linux/cdev.h>
  18 #include <linux/ioport.h>
  19 #include <linux/pci.h>
  20
  21 #include <asm/uaccess.h>
  22 #include <asm/io.h>
  23
  24
  25 #define NAME                    "cs5535_gpio"
  26
  27 MODULE_AUTHOR("Ben Gardner <bgardner@wabtec.com>");
  28 MODULE_DESCRIPTION("AMD CS5535/CS5536 GPIO Pin Driver");
  29 MODULE_LICENSE("GPL");
  30
  31 static int major;
  32 module_param(major, int, 0);
  33 MODULE_PARM_DESC(major, "Major device number");
  34
  35 static ulong mask;
  36 module_param(mask, ulong, 0);
  37 MODULE_PARM_DESC(mask, "GPIO channel mask");
  38
  39 #define MSR_LBAR_GPIO           0x5140000C
  40
  41 static u32 gpio_base;
  42
  43 static struct pci_device_id divil_pci[] = {
  44         { PCI_DEVICE(PCI_VENDOR_ID_NS,  PCI_DEVICE_ID_NS_CS5535_ISA) },
  45         { PCI_DEVICE(PCI_VENDOR_ID_AMD, PCI_DEVICE_ID_AMD_CS5536_ISA) },
  46         { } /* NULL entry */
  47 };
  48 MODULE_DEVICE_TABLE(pci, divil_pci);
  49
  50 static struct cdev cs5535_gpio_cdev;
  51
  52 /* reserve 32 entries even though some aren't usable */
  53 #define CS5535_GPIO_COUNT       32
  54
  55 /* IO block size */
  56 #define CS5535_GPIO_SIZE        256
  57
  58 struct gpio_regmap {
  59         u32     rd_offset;
  60         u32     wr_offset;
  61         char    on;
  62         char    off;
  63 };
  64 static struct gpio_regmap rm[] =
  65 {
  66         { 0x30, 0x00, '1', '0' },       /* GPIOx_READ_BACK / GPIOx_OUT_VAL */
  67         { 0x20, 0x20, 'I', 'i' },       /* GPIOx_IN_EN */
  68         { 0x04, 0x04, 'O', 'o' },       /* GPIOx_OUT_EN */
  69         { 0x08, 0x08, 't', 'T' },       /* GPIOx_OUT_OD_EN */
  70         { 0x18, 0x18, 'P', 'p' },       /* GPIOx_OUT_PU_EN */
  71         { 0x1c, 0x1c, 'D', 'd' },       /* GPIOx_OUT_PD_EN */
  72 };
  73
  74
  75 /**
  76  * Gets the register offset for the GPIO bank.
  77  * Low (0-15) starts at 0x00, high (16-31) starts at 0x80
  78  */
  79 static inline u32 cs5535_lowhigh_base(int reg)
  80 {
  81         return (reg & 0x10) << 3;
  82 }
  83
  84 static ssize_t cs5535_gpio_write(struct file *file, const char __user *data,
  85                                  size_t len, loff_t *ppos)
  86 {
  87         u32     m = iminor(file->f_path.dentry->d_inode);
  88         int     i, j;
  89         u32     base = gpio_base + cs5535_lowhigh_base(m);
  90         u32     m0, m1;
  91         char    c;
  92
  93         /**
  94          * Creates the mask for atomic bit programming.
  95          * The high 16 bits and the low 16 bits are used to set the mask.
  96          * For example, GPIO 15 maps to 31,15: 0,1 => On; 1,0=> Off
  97          */
  98         m1 = 1 << (m & 0x0F);
  99         m0 = m1 << 16;
 100
 101         for (i = 0; i < len; ++i) {
 102                 if (get_user(c, data+i))
 103                         return -EFAULT;
 104
 105                 for (j = 0; j < ARRAY_SIZE(rm); j++) {
 106                         if (c == rm[j].on) {
 107                                 outl(m1, base + rm[j].wr_offset);
 108                                 /* If enabling output, turn off AUX 1 and AUX 2 */
 109                                 if (c == 'O') {
 110                                         outl(m0, base + 0x10);
 111                                         outl(m0, base + 0x14);
 112                                 }
 113                                 break;
 114                         } else if (c == rm[j].off) {
 115                                 outl(m0, base + rm[j].wr_offset);
 116                                 break;
 117                         }
 118                 }
 119         }
 120         *ppos = 0;
 121         return len;
 122 }
 123
 124 static ssize_t cs5535_gpio_read(struct file *file, char __user *buf,
 125                                 size_t len, loff_t *ppos)
 126 {
 127         u32     m = iminor(file->f_path.dentry->d_inode);
 128         u32     base = gpio_base + cs5535_lowhigh_base(m);
 129         int     rd_bit = 1 << (m & 0x0f);
 130         int     i;
 131         char    ch;
 132         ssize_t count = 0;
 133
 134         if (*ppos >= ARRAY_SIZE(rm))
 135                 return 0;
 136
 137         for (i = *ppos; (i < (*ppos + len)) && (i < ARRAY_SIZE(rm)); i++) {
 138                 ch = (inl(base + rm[i].rd_offset) & rd_bit) ?
 139                      rm[i].on : rm[i].off;
 140
 141                 if (put_user(ch, buf+count))
 142                         return -EFAULT;
 143
 144                 count++;
 145         }
 146
 147         /* add a line-feed if there is room */
 148         if ((i == ARRAY_SIZE(rm)) && (count < len)) {
 149                 put_user('\n', buf + count);
 150                 count++;
 151         }
 152
 153         *ppos += count;
 154         return count;
 155 }
 156
 157 static int cs5535_gpio_open(struct inode *inode, struct file *file)
 158 {
 159         u32 m = iminor(inode);
 160
 161         /* the mask says which pins are usable by this driver */
 162         if ((mask & (1 << m)) == 0)
 163                 return -EINVAL;
 164
 165         return nonseekable_open(inode, file);
 166 }
 167
 168 static const struct file_operations cs5535_gpio_fops = {
 169         .owner  = THIS_MODULE,
 170         .write  = cs5535_gpio_write,
 171         .read   = cs5535_gpio_read,
 172         .open   = cs5535_gpio_open
 173 };
 174
 175 static int __init cs5535_gpio_init(void)
 176 {
 177         dev_t   dev_id;
 178         u32     low, hi;
 179         int     retval;
 180
 181         if (pci_dev_present(divil_pci) == 0) {
 182                 printk(KERN_WARNING NAME ": DIVIL not found\n");
 183                 return -ENODEV;
 184         }
 185
 186         /* Grab the GPIO I/O range */
 187         rdmsr(MSR_LBAR_GPIO, low, hi);
 188
 189         /* Check the mask and whether GPIO is enabled (sanity check) */
 190         if (hi != 0x0000f001) {
 191                 printk(KERN_WARNING NAME ": GPIO not enabled\n");
 192                 return -ENODEV;
 193         }
 194
 195         /* Mask off the IO base address */
 196         gpio_base = low & 0x0000ff00;
 197
 198         /**
 199          * Some GPIO pins
 200          *  31-29,23 : reserved (always mask out)
 201          *  28       : Power Button
 202          *  26       : PME#
 203          *  22-16    : LPC
 204          *  14,15    : SMBus
 205          *  9,8      : UART1
 206          *  7        : PCI INTB
 207          *  3,4      : UART2/DDC
 208          *  2        : IDE_IRQ0
 209          *  0        : PCI INTA
 210          *
 211          * If a mask was not specified, be conservative and only allow:
 212          *  1,2,5,6,10-13,24,25,27
 213          */
 214         if (mask != 0)
 215                 mask &= 0x1f7fffff;
 216         else
 217                 mask = 0x0b003c66;
 218
 219         if (!request_region(gpio_base, CS5535_GPIO_SIZE, NAME)) {
 220                 printk(KERN_ERR NAME ": can't allocate I/O for GPIO\n");
 221                 return -ENODEV;
 222         }
 223
 224         if (major) {
 225                 dev_id = MKDEV(major, 0);
 226                 retval = register_chrdev_region(dev_id, CS5535_GPIO_COUNT,
 227                                                 NAME);
 228         } else {
 229                 retval = alloc_chrdev_region(&dev_id, 0, CS5535_GPIO_COUNT,
 230                                              NAME);
 231                 major = MAJOR(dev_id);
 232         }
 233
 234         if (retval) {
 235                 release_region(gpio_base, CS5535_GPIO_SIZE);
 236                 return -1;
 237         }
 238
 239         printk(KERN_DEBUG NAME ": base=%#x mask=%#lx major=%d\n",
 240                gpio_base, mask, major);
 241
 242         cdev_init(&cs5535_gpio_cdev, &cs5535_gpio_fops);
 243         cdev_add(&cs5535_gpio_cdev, dev_id, CS5535_GPIO_COUNT);
 244
 245         return 0;
 246 }
 247
 248 static void __exit cs5535_gpio_cleanup(void)
 249 {
 250         dev_t dev_id = MKDEV(major, 0);
 251
 252         cdev_del(&cs5535_gpio_cdev);
 253         unregister_chrdev_region(dev_id, CS5535_GPIO_COUNT);
 254         release_region(gpio_base, CS5535_GPIO_SIZE);
 255 }
 256
 257 module_init(cs5535_gpio_init);
 258 module_exit(cs5535_gpio_cleanup);