drivers/i2c/busses/i2c-pca-isa.c

   1 /*
   2  *  i2c-pca-isa.c driver for PCA9564 on ISA boards
   3  *    Copyright (C) 2004 Arcom Control Systems
   4  *    Copyright (C) 2008 Pengutronix
   5  *
   6  *  This program is free software; you can redistribute it and/or modify
   7  *  it under the terms of the GNU General Public License as published by
   8  *  the Free Software Foundation; either version 2 of the License, or
   9  *  (at your option) any later version.
  10  *
  11  *  This program is distributed in the hope that it will be useful,
  12  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14  *  GNU General Public License for more details.
  15  *
  16  *  You should have received a copy of the GNU General Public License
  17  *  along with this program; if not, write to the Free Software
  18  *  Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  19  */
  20
  21 #include <linux/kernel.h>
  22 #include <linux/ioport.h>
  23 #include <linux/module.h>
  24 #include <linux/moduleparam.h>
  25 #include <linux/delay.h>
  26 #include <linux/init.h>
  27 #include <linux/interrupt.h>
  28 #include <linux/wait.h>
  29 #include <linux/isa.h>
  30 #include <linux/i2c.h>
  31 #include <linux/i2c-algo-pca.h>
  32
  33 #include <asm/io.h>
  34 #include <asm/irq.h>
  35
  36 #define DRIVER "i2c-pca-isa"
  37 #define IO_SIZE 4
  38
  39 static unsigned long base;
  40 static int irq = -1;
  41
  42 /* Data sheet recommends 59kHz for 100kHz operation due to variation
  43  * in the actual clock rate */
  44 static int clock  = I2C_PCA_CON_59kHz;
  45
  46 static wait_queue_head_t pca_wait;
  47
  48 static void pca_isa_writebyte(void *pd, int reg, int val)
  49 {
  50 #ifdef DEBUG_IO
  51         static char *names[] = { "T/O", "DAT", "ADR", "CON" };
  52         printk("*** write %s at %#lx <= %#04x\n", names[reg], base+reg, val);
  53 #endif
  54         outb(val, base+reg);
  55 }
  56
  57 static int pca_isa_readbyte(void *pd, int reg)
  58 {
  59         int res = inb(base+reg);
  60 #ifdef DEBUG_IO
  61         {
  62                 static char *names[] = { "STA", "DAT", "ADR", "CON" };
  63                 printk("*** read  %s => %#04x\n", names[reg], res);
  64         }
  65 #endif
  66         return res;
  67 }
  68
  69 static int pca_isa_waitforcompletion(void *pd)
  70 {
  71         int ret = 0;
  72
  73         if (irq > -1) {
  74                 ret = wait_event_interruptible(pca_wait,
  75                                                pca_isa_readbyte(pd, I2C_PCA_CON) & I2C_PCA_CON_SI);
  76         } else {
  77                 while ((pca_isa_readbyte(pd, I2C_PCA_CON) & I2C_PCA_CON_SI) == 0)
  78                         udelay(100);
  79         }
  80         return ret;
  81 }
  82
  83 static void pca_isa_resetchip(void *pd)
  84 {
  85         /* apparently only an external reset will do it. not a lot can be done */
  86         printk(KERN_WARNING DRIVER ": Haven't figured out how to do a reset yet\n");
  87 }
  88
  89 static irqreturn_t pca_handler(int this_irq, void *dev_id) {
  90         wake_up_interruptible(&pca_wait);
  91         return IRQ_HANDLED;
  92 }
  93
  94 static struct i2c_algo_pca_data pca_isa_data = {
  95         /* .data intentionally left NULL, not needed with ISA */
  96         .write_byte             = pca_isa_writebyte,
  97         .read_byte              = pca_isa_readbyte,
  98         .wait_for_completion    = pca_isa_waitforcompletion,
  99         .reset_chip             = pca_isa_resetchip,
 100 };
 101
 102 static struct i2c_adapter pca_isa_ops = {
 103         .owner          = THIS_MODULE,
 104         .id             = I2C_HW_A_ISA,
 105         .algo_data      = &pca_isa_data,
 106         .name           = "PCA9564 ISA Adapter",
 107         .timeout        = 100,
 108 };
 109
 110 static int __devinit pca_isa_match(struct device *dev, unsigned int id)
 111 {
 112         int match = base != 0;
 113
 114         if (match) {
 115                 if (irq <= -1)
 116                         dev_warn(dev, "Using polling mode (specify irq)\n");
 117         } else
 118                 dev_err(dev, "Please specify I/O base\n");
 119
 120         return match;
 121 }
 122
 123 static int __devinit pca_isa_probe(struct device *dev, unsigned int id)
 124 {
 125         init_waitqueue_head(&pca_wait);
 126
 127         dev_info(dev, "i/o base %#08lx. irq %d\n", base, irq);
 128
 129 #ifdef CONFIG_PPC
 130         if (check_legacy_ioport(base)) {
 131                 dev_err(dev, "I/O address %#08lx is not available\n", base);
 132                 goto out;
 133         }
 134 #endif
 135
 136         if (!request_region(base, IO_SIZE, "i2c-pca-isa")) {
 137                 dev_err(dev, "I/O address %#08lx is in use\n", base);
 138                 goto out;
 139         }
 140
 141         if (irq > -1) {
 142                 if (request_irq(irq, pca_handler, 0, "i2c-pca-isa", &pca_isa_ops) < 0) {
 143                         dev_err(dev, "Request irq%d failed\n", irq);
 144                         goto out_region;
 145                 }
 146         }
 147
 148         pca_isa_data.i2c_clock = clock;
 149         if (i2c_pca_add_bus(&pca_isa_ops) < 0) {
 150                 dev_err(dev, "Failed to add i2c bus\n");
 151                 goto out_irq;
 152         }
 153
 154         return 0;
 155
 156  out_irq:
 157         if (irq > -1)
 158                 free_irq(irq, &pca_isa_ops);
 159  out_region:
 160         release_region(base, IO_SIZE);
 161  out:
 162         return -ENODEV;
 163 }
 164
 165 static int __devexit pca_isa_remove(struct device *dev, unsigned int id)
 166 {
 167         i2c_del_adapter(&pca_isa_ops);
 168
 169         if (irq > -1) {
 170                 disable_irq(irq);
 171                 free_irq(irq, &pca_isa_ops);
 172         }
 173         release_region(base, IO_SIZE);
 174
 175         return 0;
 176 }
 177
 178 static struct isa_driver pca_isa_driver = {
 179         .match          = pca_isa_match,
 180         .probe          = pca_isa_probe,
 181         .remove         = __devexit_p(pca_isa_remove),
 182         .driver = {
 183                 .owner  = THIS_MODULE,
 184                 .name   = DRIVER,
 185         }
 186 };
 187
 188 static int __init pca_isa_init(void)
 189 {
 190         return isa_register_driver(&pca_isa_driver, 1);
 191 }
 192
 193 static void __exit pca_isa_exit(void)
 194 {
 195         isa_unregister_driver(&pca_isa_driver);
 196 }
 197
 198 MODULE_AUTHOR("Ian Campbell <icampbell@arcom.com>");
 199 MODULE_DESCRIPTION("ISA base PCA9564 driver");
 200 MODULE_LICENSE("GPL");
 201
 202 module_param(base, ulong, 0);
 203 MODULE_PARM_DESC(base, "I/O base address");
 204
 205 module_param(irq, int, 0);
 206 MODULE_PARM_DESC(irq, "IRQ");
 207 module_param(clock, int, 0);
 208 MODULE_PARM_DESC(clock, "Clock rate as described in table 1 of PCA9564 datasheet");
 209
 210 module_init(pca_isa_init);
 211 module_exit(pca_isa_exit);