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