drivers/i2c/busses/i2c-ite.c

   1 /*
   2    -------------------------------------------------------------------------
   3    i2c-adap-ite.c i2c-hw access for the IIC peripheral on the ITE MIPS system
   4    -------------------------------------------------------------------------
   5    Hai-Pao Fan, MontaVista Software, Inc.
   6    hpfan@mvista.com or source@mvista.com
   7
   8    Copyright 2001 MontaVista Software Inc.
   9
  10    ----------------------------------------------------------------------------
  11    This file was highly leveraged from i2c-elektor.c, which was created
  12    by Simon G. Vogl and Hans Berglund:
  13
  14
  15      Copyright (C) 1995-97 Simon G. Vogl
  16                    1998-99 Hans Berglund
  17
  18     This program is free software; you can redistribute it and/or modify
  19     it under the terms of the GNU General Public License as published by
  20     the Free Software Foundation; either version 2 of the License, or
  21     (at your option) any later version.
  22
  23     This program is distributed in the hope that it will be useful,
  24     but WITHOUT ANY WARRANTY; without even the implied warranty of
  25     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  26     GNU General Public License for more details.
  27
  28     You should have received a copy of the GNU General Public License
  29     along with this program; if not, write to the Free Software
  30     Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.                */
  31 /* ------------------------------------------------------------------------- */
  32
  33 /* With some changes from Kyösti Mälkki <kmalkki@cc.hut.fi> and even
  34    Frodo Looijaard <frodol@dds.nl> */
  35
  36 #include <linux/config.h>
  37 #include <linux/kernel.h>
  38 #include <linux/ioport.h>
  39 #include <linux/module.h>
  40 #include <linux/delay.h>
  41 #include <linux/slab.h>
  42 #include <linux/init.h>
  43 #include <linux/wait.h>
  44 #include <asm/irq.h>
  45 #include <asm/io.h>
  46
  47 #include <linux/i2c.h>
  48 #include <linux/i2c-algo-ite.h>
  49 #include <linux/i2c-adap-ite.h>
  50 #include "../i2c-ite.h"
  51
  52 #define DEFAULT_BASE  0x14014030
  53 #define ITE_IIC_IO_SIZE 0x40
  54 #define DEFAULT_IRQ   0
  55 #define DEFAULT_CLOCK 0x1b0e    /* default 16MHz/(27+14) = 400KHz */
  56 #define DEFAULT_OWN   0x55
  57
  58 static int base;
  59 static int irq;
  60 static int clock;
  61 static int own;
  62
  63 static struct iic_ite gpi;
  64 static wait_queue_head_t iic_wait;
  65 static int iic_pending;
  66 static spinlock_t lock;
  67
  68 /* ----- local functions ---------------------------------------------- */
  69
  70 static void iic_ite_setiic(void *data, int ctl, short val)
  71 {
  72         unsigned long j = jiffies + 10;
  73
  74         pr_debug(" Write 0x%02x to 0x%x\n",(unsigned short)val, ctl&0xff);
  75 #ifdef DEBUG
  76         while (time_before(jiffies, j))
  77                 schedule();
  78 #endif
  79         outw(val,ctl);
  80 }
  81
  82 static short iic_ite_getiic(void *data, int ctl)
  83 {
  84         short val;
  85
  86         val = inw(ctl);
  87         pr_debug("Read 0x%02x from 0x%x\n",(unsigned short)val, ctl&0xff);
  88         return (val);
  89 }
  90
  91 /* Return our slave address.  This is the address
  92  * put on the I2C bus when another master on the bus wants to address us
  93  * as a slave
  94  */
  95 static int iic_ite_getown(void *data)
  96 {
  97         return (gpi.iic_own);
  98 }
  99
 100
 101 static int iic_ite_getclock(void *data)
 102 {
 103         return (gpi.iic_clock);
 104 }
 105
 106
 107 /* Put this process to sleep.  We will wake up when the
 108  * IIC controller interrupts.
 109  */
 110 static void iic_ite_waitforpin(void) {
 111    DEFINE_WAIT(wait);
 112    int timeout = 2;
 113    long flags;
 114
 115    /* If interrupts are enabled (which they are), then put the process to
 116     * sleep.  This process will be awakened by two events -- either the
 117     * the IIC peripheral interrupts or the timeout expires.
 118     * If interrupts are not enabled then delay for a reasonable amount
 119     * of time and return.
 120     */
 121    if (gpi.iic_irq > 0) {
 122         spin_lock_irqsave(&lock, flags);
 123         if (iic_pending == 0) {
 124                 spin_unlock_irqrestore(&lock, flags);
 125                 prepare_to_wait(&iic_wait, &wait, TASK_INTERRUPTIBLE);
 126                 if (schedule_timeout(timeout*HZ)) {
 127                         spin_lock_irqsave(&lock, flags);
 128                         if (iic_pending == 1) {
 129                                 iic_pending = 0;
 130                         }
 131                         spin_unlock_irqrestore(&lock, flags);
 132                 }
 133                 finish_wait(&iic_wait, &wait);
 134         } else {
 135                 iic_pending = 0;
 136                 spin_unlock_irqrestore(&lock, flags);
 137         }
 138    } else {
 139       udelay(100);
 140    }
 141 }
 142
 143
 144 static irqreturn_t iic_ite_handler(int this_irq, void *dev_id,
 145                                                         struct pt_regs *regs)
 146 {
 147         spin_lock(&lock);
 148         iic_pending = 1;
 149         spin_unlock(&lock);
 150
 151         wake_up_interruptible(&iic_wait);
 152
 153         return IRQ_HANDLED;
 154 }
 155
 156
 157 /* Lock the region of memory where I/O registers exist.  Request our
 158  * interrupt line and register its associated handler.
 159  */
 160 static int iic_hw_resrc_init(void)
 161 {
 162         if (!request_region(gpi.iic_base, ITE_IIC_IO_SIZE, "i2c"))
 163                 return -ENODEV;
 164
 165         if (gpi.iic_irq <= 0)
 166                 return 0;
 167
 168         if (request_irq(gpi.iic_irq, iic_ite_handler, 0, "ITE IIC", 0) < 0)
 169                 gpi.iic_irq = 0;
 170         else
 171                 enable_irq(gpi.iic_irq);
 172
 173         return 0;
 174 }
 175
 176
 177 static void iic_ite_release(void)
 178 {
 179         if (gpi.iic_irq > 0) {
 180                 disable_irq(gpi.iic_irq);
 181                 free_irq(gpi.iic_irq, 0);
 182         }
 183         release_region(gpi.iic_base , 2);
 184 }
 185
 186 /* ------------------------------------------------------------------------
 187  * Encapsulate the above functions in the correct operations structure.
 188  * This is only done when more than one hardware adapter is supported.
 189  */
 190 static struct i2c_algo_iic_data iic_ite_data = {
 191         NULL,
 192         iic_ite_setiic,
 193         iic_ite_getiic,
 194         iic_ite_getown,
 195         iic_ite_getclock,
 196         iic_ite_waitforpin,
 197         80, 80, 100,            /*      waits, timeout */
 198 };
 199
 200 static struct i2c_adapter iic_ite_ops = {
 201         .owner          = THIS_MODULE,
 202         .id             = I2C_HW_I_IIC,
 203         .algo_data      = &iic_ite_data,
 204         .dev            = {
 205                 .name   = "ITE IIC adapter",
 206         },
 207 };
 208
 209 /* Called when the module is loaded.  This function starts the
 210  * cascade of calls up through the hierarchy of i2c modules (i.e. up to the
 211  *  algorithm layer and into to the core layer)
 212  */
 213 static int __init iic_ite_init(void)
 214 {
 215
 216         struct iic_ite *piic = &gpi;
 217
 218         printk(KERN_INFO "Initialize ITE IIC adapter module\n");
 219         if (base == 0)
 220                 piic->iic_base = DEFAULT_BASE;
 221         else
 222                 piic->iic_base = base;
 223
 224         if (irq == 0)
 225                 piic->iic_irq = DEFAULT_IRQ;
 226         else
 227                 piic->iic_irq = irq;
 228
 229         if (clock == 0)
 230                 piic->iic_clock = DEFAULT_CLOCK;
 231         else
 232                 piic->iic_clock = clock;
 233
 234         if (own == 0)
 235                 piic->iic_own = DEFAULT_OWN;
 236         else
 237                 piic->iic_own = own;
 238
 239         iic_ite_data.data = (void *)piic;
 240         init_waitqueue_head(&iic_wait);
 241         spin_lock_init(&lock);
 242         if (iic_hw_resrc_init() == 0) {
 243                 if (i2c_iic_add_bus(&iic_ite_ops) < 0)
 244                         return -ENODEV;
 245         } else {
 246                 return -ENODEV;
 247         }
 248         printk(KERN_INFO " found device at %#x irq %d.\n",
 249                 piic->iic_base, piic->iic_irq);
 250         return 0;
 251 }
 252
 253
 254 static void iic_ite_exit(void)
 255 {
 256         i2c_iic_del_bus(&iic_ite_ops);
 257         iic_ite_release();
 258 }
 259
 260 /* If modules is NOT defined when this file is compiled, then the MODULE_*
 261  * macros will resolve to nothing
 262  */
 263 MODULE_AUTHOR("MontaVista Software <www.mvista.com>");
 264 MODULE_DESCRIPTION("I2C-Bus adapter routines for ITE IIC bus adapter");
 265 MODULE_LICENSE("GPL");
 266
 267 module_param(base, int, 0);
 268 module_param(irq, int, 0);
 269 module_param(clock, int, 0);
 270 module_param(own, int, 0);
 271
 272
 273 /* Called when module is loaded or when kernel is initialized.
 274  * If MODULES is defined when this file is compiled, then this function will
 275  * resolve to init_module (the function called when insmod is invoked for a
 276  * module).  Otherwise, this function is called early in the boot, when the
 277  * kernel is intialized.  Check out /include/init.h to see how this works.
 278  */
 279 module_init(iic_ite_init);
 280
 281 /* Resolves to module_cleanup when MODULES is defined. */
 282 module_exit(iic_ite_exit);