arch/arm/mach-sa1100/jornada720_ssp.c

   1 /**
   2  *  arch/arm/mac-sa1100/jornada720_ssp.c
   3  *
   4  *  Copyright (C) 2006/2007 Kristoffer Ericson <Kristoffer.Ericson@gmail.com>
   5  *   Copyright (C) 2006 Filip Zyzniewski <filip.zyzniewski@tefnet.pl>
   6  *
   7  * This program is free software; you can redistribute it and/or modify
   8  * it under the terms of the GNU General Public License version 2 as
   9  * published by the Free Software Foundation.
  10  *
  11  *  SSP driver for the HP Jornada 710/720/728
  12  */
  13
  14 #include <linux/delay.h>
  15 #include <linux/errno.h>
  16 #include <linux/init.h>
  17 #include <linux/kernel.h>
  18 #include <linux/module.h>
  19 #include <linux/platform_device.h>
  20 #include <linux/sched.h>
  21 #include <linux/slab.h>
  22
  23 #include <asm/hardware.h>
  24 #include <asm/hardware/ssp.h>
  25 #include <asm/arch/jornada720.h>
  26
  27 static DEFINE_SPINLOCK(jornada_ssp_lock);
  28 static unsigned long jornada_ssp_flags;
  29
  30 /**
  31  * jornada_ssp_reverse - reverses input byte
  32  *
  33  * we need to reverse all data we recieve from the mcu due to its physical location
  34  * returns : 01110111 -> 11101110
  35  */
  36 u8 inline jornada_ssp_reverse(u8 byte)
  37 {
  38         return
  39                 ((0x80 & byte) >> 7) |
  40                 ((0x40 & byte) >> 5) |
  41                 ((0x20 & byte) >> 3) |
  42                 ((0x10 & byte) >> 1) |
  43                 ((0x08 & byte) << 1) |
  44                 ((0x04 & byte) << 3) |
  45                 ((0x02 & byte) << 5) |
  46                 ((0x01 & byte) << 7);
  47 };
  48 EXPORT_SYMBOL(jornada_ssp_reverse);
  49
  50 /**
  51  * jornada_ssp_byte - waits for ready ssp bus and sends byte
  52  *
  53  * waits for fifo buffer to clear and then transmits, if it doesn't then we will
  54  * timeout after <timeout> rounds. Needs mcu running before its called.
  55  *
  56  * returns : %mcu output on success
  57  *         : %-ETIMEOUT on timeout
  58  */
  59 int jornada_ssp_byte(u8 byte)
  60 {
  61         int timeout = 400000;
  62         u16 ret;
  63
  64         while ((GPLR & GPIO_GPIO10)) {
  65                 if (!--timeout) {
  66                         printk(KERN_WARNING "SSP: timeout while waiting for transmit\n");
  67                         return -ETIMEDOUT;
  68                 }
  69                 cpu_relax();
  70         }
  71
  72         ret = jornada_ssp_reverse(byte) << 8;
  73
  74         ssp_write_word(ret);
  75         ssp_read_word(&ret);
  76
  77         return jornada_ssp_reverse(ret);
  78 };
  79 EXPORT_SYMBOL(jornada_ssp_byte);
  80
  81 /**
  82  * jornada_ssp_inout - decide if input is command or trading byte
  83  *
  84  * returns : (jornada_ssp_byte(byte)) on success
  85  *         : %-ETIMEOUT on timeout failure
  86  */
  87 int jornada_ssp_inout(u8 byte)
  88 {
  89         int ret, i;
  90
  91         /* true means command byte */
  92         if (byte != TXDUMMY) {
  93                 ret = jornada_ssp_byte(byte);
  94                 /* Proper return to commands is TxDummy */
  95                 if (ret != TXDUMMY) {
  96                         for (i = 0; i < 256; i++)/* flushing bus */
  97                                 if (jornada_ssp_byte(TXDUMMY) == -1)
  98                                         break;
  99                         return -ETIMEDOUT;
 100                 }
 101         } else /* Exchange TxDummy for data */
 102                 ret = jornada_ssp_byte(TXDUMMY);
 103
 104         return ret;
 105 };
 106 EXPORT_SYMBOL(jornada_ssp_inout);
 107
 108 /**
 109  * jornada_ssp_start - enable mcu
 110  *
 111  */
 112 int jornada_ssp_start()
 113 {
 114         spin_lock_irqsave(&jornada_ssp_lock, jornada_ssp_flags);
 115         GPCR = GPIO_GPIO25;
 116         udelay(50);
 117         return 0;
 118 };
 119 EXPORT_SYMBOL(jornada_ssp_start);
 120
 121 /**
 122  * jornada_ssp_end - disable mcu and turn off lock
 123  *
 124  */
 125 int jornada_ssp_end()
 126 {
 127         GPSR = GPIO_GPIO25;
 128         spin_unlock_irqrestore(&jornada_ssp_lock, jornada_ssp_flags);
 129         return 0;
 130 };
 131 EXPORT_SYMBOL(jornada_ssp_end);
 132
 133 static int __init jornada_ssp_probe(struct platform_device *dev)
 134 {
 135         int ret;
 136
 137         GPSR = GPIO_GPIO25;
 138
 139         ret = ssp_init();
 140
 141         /* worked fine, lets not bother with anything else */
 142         if (!ret) {
 143                 printk(KERN_INFO "SSP: device initialized with irq\n");
 144                 return ret;
 145         }
 146
 147         printk(KERN_WARNING "SSP: initialization failed, trying non-irq solution \n");
 148
 149         /* init of Serial 4 port */
 150         Ser4MCCR0 = 0;
 151         Ser4SSCR0 = 0x0387;
 152         Ser4SSCR1 = 0x18;
 153
 154         /* clear out any left over data */
 155         ssp_flush();
 156
 157         /* enable MCU */
 158         jornada_ssp_start();
 159
 160         /* see if return value makes sense */
 161         ret = jornada_ssp_inout(GETBRIGHTNESS);
 162
 163         /* seems like it worked, just feed it with TxDummy to get rid of data */
 164         if (ret == TXDUMMY)
 165                 jornada_ssp_inout(TXDUMMY);
 166
 167         jornada_ssp_end();
 168
 169         /* failed, lets just kill everything */
 170         if (ret == -ETIMEDOUT) {
 171                 printk(KERN_WARNING "SSP: attempts failed, bailing\n");
 172                 ssp_exit();
 173                 return -ENODEV;
 174         }
 175
 176         /* all fine */
 177         printk(KERN_INFO "SSP: device initialized\n");
 178         return 0;
 179 };
 180
 181 static int jornada_ssp_remove(struct platform_device *dev)
 182 {
 183         /* Note that this doesnt actually remove the driver, since theres nothing to remove
 184          * It just makes sure everything is turned off */
 185         GPSR = GPIO_GPIO25;
 186         ssp_exit();
 187         return 0;
 188 };
 189
 190 struct platform_driver jornadassp_driver = {
 191         .probe  = jornada_ssp_probe,
 192         .remove = jornada_ssp_remove,
 193         .driver = {
 194                 .name   = "jornada_ssp",
 195         },
 196 };
 197
 198 static int __init jornada_ssp_init(void)
 199 {
 200         return platform_driver_register(&jornadassp_driver);
 201 }