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