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