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/kernel.h>
  37 #include <linux/ioport.h>
  38 #include <linux/module.h>
  39 #include <linux/delay.h>
  40 #include <linux/slab.h>
  41 #include <linux/init.h>
  42 #include <linux/wait.h>
  43 #include <asm/irq.h>
  44 #include <asm/io.h>
  45
  46 #include <linux/i2c.h>
  47 #include <linux/i2c-algo-ite.h>
  48 #include <linux/i2c-adap-ite.h>
  49 #include "../i2c-ite.h"
  50
  51 #define DEFAULT_BASE  0x14014030
  52 #define ITE_IIC_IO_SIZE 0x40
  53 #define DEFAULT_IRQ   0
  54 #define DEFAULT_CLOCK 0x1b0e    /* default 16MHz/(27+14) = 400KHz */
  55 #define DEFAULT_OWN   0x55
  56
  57 static int base;
  58 static int irq;
  59 static int clock;
  60 static int own;
  61
  62 static struct iic_ite gpi;
  63 static wait_queue_head_t iic_wait;
  64 static int iic_pending;
  65 static spinlock_t lock;
  66
  67 /* ----- local functions ---------------------------------------------- */
  68
  69 static void iic_ite_setiic(void *data, int ctl, short val)
  70 {
  71         unsigned long j = jiffies + 10;
  72
  73         pr_debug(" Write 0x%02x to 0x%x\n",(unsigned short)val, ctl&0xff);
  74 #ifdef DEBUG
  75         while (time_before(jiffies, j))
  76                 schedule();
  77 #endif
  78         outw(val,ctl);
  79 }
  80
  81 static short iic_ite_getiic(void *data, int ctl)
  82 {
  83         short val;
  84
  85         val = inw(ctl);
  86         pr_debug("Read 0x%02x from 0x%x\n",(unsigned short)val, ctl&0xff);
  87         return (val);
  88 }
  89
  90 /* Return our slave address.  This is the address
  91  * put on the I2C bus when another master on the bus wants to address us
  92  * as a slave
  93  */
  94 static int iic_ite_getown(void *data)
  95 {
  96         return (gpi.iic_own);
  97 }
  98
  99
 100 static int iic_ite_getclock(void *data)
 101 {
 102         return (gpi.iic_clock);
 103 }
 104
 105
 106 /* Put this process to sleep.  We will wake up when the
 107  * IIC controller interrupts.
 108  */
 109 static void iic_ite_waitforpin(void) {
 110    DEFINE_WAIT(wait);
 111    int timeout = 2;
 112    long flags;
 113
 114    /* If interrupts are enabled (which they are), then put the process to
 115     * sleep.  This process will be awakened by two events -- either the
 116     * the IIC peripheral interrupts or the timeout expires.
 117     * If interrupts are not enabled then delay for a reasonable amount
 118     * of time and return.
 119     */
 120    if (gpi.iic_irq > 0) {
 121         spin_lock_irqsave(&lock, flags);
 122         if (iic_pending == 0) {
 123                 spin_unlock_irqrestore(&lock, flags);
 124                 prepare_to_wait(&iic_wait, &wait, TASK_INTERRUPTIBLE);
 125                 if (schedule_timeout(timeout*HZ)) {
 126                         spin_lock_irqsave(&lock, flags);
 127                         if (iic_pending == 1) {
 128                                 iic_pending = 0;
 129                         }
 130                         spin_unlock_irqrestore(&lock, flags);
 131                 }
 132                 finish_wait(&iic_wait, &wait);
 133         } else {
 134                 iic_pending = 0;
 135                 spin_unlock_irqrestore(&lock, flags);
 136         }
 137    } else {
 138       udelay(100);
 139    }
 140 }
 141
 142
 143 static irqreturn_t iic_ite_handler(int this_irq, void *dev_id,
 144                                                         struct pt_regs *regs)
 145 {
 146         spin_lock(&lock);
 147         iic_pending = 1;
 148         spin_unlock(&lock);
 149
 150         wake_up_interruptible(&iic_wait);
 151
 152         return IRQ_HANDLED;
 153 }
 154
 155
 156 /* Lock the region of memory where I/O registers exist.  Request our
 157  * interrupt line and register its associated handler.
 158  */
 159 static int iic_hw_resrc_init(void)
 160 {
 161         if (!request_region(gpi.iic_base, ITE_IIC_IO_SIZE, "i2c"))
 162                 return -ENODEV;
 163
 164         if (gpi.iic_irq <= 0)
 165                 return 0;
 166
 167         if (request_irq(gpi.iic_irq, iic_ite_handler, 0, "ITE IIC", 0) < 0)
 168                 gpi.iic_irq = 0;
 169         else
 170                 enable_irq(gpi.iic_irq);
 171
 172         return 0;
 173 }
 174
 175
 176 static void iic_ite_release(void)
 177 {
 178         if (gpi.iic_irq > 0) {
 179                 disable_irq(gpi.iic_irq);
 180                 free_irq(gpi.iic_irq, 0);
 181         }
 182         release_region(gpi.iic_base , 2);
 183 }
 184
 185 /* ------------------------------------------------------------------------
 186  * Encapsulate the above functions in the correct operations structure.
 187  * This is only done when more than one hardware adapter is supported.
 188  */
 189 static struct i2c_algo_iic_data iic_ite_data = {
 190         NULL,
 191         iic_ite_setiic,
 192         iic_ite_getiic,
 193         iic_ite_getown,
 194         iic_ite_getclock,
 195         iic_ite_waitforpin,
 196         80, 80, 100,            /*      waits, timeout */
 197 };
 198
 199 static struct i2c_adapter iic_ite_ops = {
 200         .owner          = THIS_MODULE,
 201         .id             = I2C_HW_I_IIC,
 202         .algo_data      = &iic_ite_data,
 203         .dev            = {
 204                 .name   = "ITE IIC adapter",
 205         },
 206 };
 207
 208 /* Called when the module is loaded.  This function starts the
 209  * cascade of calls up through the hierarchy of i2c modules (i.e. up to the
 210  *  algorithm layer and into to the core layer)
 211  */
 212 static int __init iic_ite_init(void)
 213 {
 214
 215         struct iic_ite *piic = &gpi;
 216
 217         printk(KERN_INFO "Initialize ITE IIC adapter module\n");
 218         if (base == 0)
 219                 piic->iic_base = DEFAULT_BASE;
 220         else
 221                 piic->iic_base = base;
 222
 223         if (irq == 0)
 224                 piic->iic_irq = DEFAULT_IRQ;
 225         else
 226                 piic->iic_irq = irq;
 227
 228         if (clock == 0)
 229                 piic->iic_clock = DEFAULT_CLOCK;
 230         else
 231                 piic->iic_clock = clock;
 232
 233         if (own == 0)
 234                 piic->iic_own = DEFAULT_OWN;
 235         else
 236                 piic->iic_own = own;
 237
 238         iic_ite_data.data = (void *)piic;
 239         init_waitqueue_head(&iic_wait);
 240         spin_lock_init(&lock);
 241         if (iic_hw_resrc_init() == 0) {
 242                 if (i2c_iic_add_bus(&iic_ite_ops) < 0)
 243                         return -ENODEV;
 244         } else {
 245                 return -ENODEV;
 246         }
 247         printk(KERN_INFO " found device at %#x irq %d.\n",
 248                 piic->iic_base, piic->iic_irq);
 249         return 0;
 250 }
 251
 252
 253 static void iic_ite_exit(void)
 254 {
 255         i2c_iic_del_bus(&iic_ite_ops);
 256         iic_ite_release();
 257 }
 258
 259 /* If modules is NOT defined when this file is compiled, then the MODULE_*
 260  * macros will resolve to nothing
 261  */
 262 MODULE_AUTHOR("MontaVista Software <www.mvista.com>");
 263 MODULE_DESCRIPTION("I2C-Bus adapter routines for ITE IIC bus adapter");
 264 MODULE_LICENSE("GPL");
 265
 266 module_param(base, int, 0);
 267 module_param(irq, int, 0);
 268 module_param(clock, int, 0);
 269 module_param(own, int, 0);
 270
 271
 272 /* Called when module is loaded or when kernel is initialized.
 273  * If MODULES is defined when this file is compiled, then this function will
 274  * resolve to init_module (the function called when insmod is invoked for a
 275  * module).  Otherwise, this function is called early in the boot, when the
 276  * kernel is intialized.  Check out /include/init.h to see how this works.
 277  */
 278 module_init(iic_ite_init);
 279
 280 /* Resolves to module_cleanup when MODULES is defined. */
 281 module_exit(iic_ite_exit);