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Linux/arch/arm/mach-sa1100/jornada720_ssp.c

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  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/io.h>
 22 
 23 #include <mach/hardware.h>
 24 #include <mach/jornada720.h>
 25 #include <asm/hardware/ssp.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 receive from the mcu due to its physical location
 34  * returns : 01110111 -> 11101110
 35  */
 36 inline u8 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  *         : %-ETIMEDOUT 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  *         : %-ETIMEDOUT 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 void jornada_ssp_start(void)
113 {
114         spin_lock_irqsave(&jornada_ssp_lock, jornada_ssp_flags);
115         GPCR = GPIO_GPIO25;
116         udelay(50);
117         return;
118 };
119 EXPORT_SYMBOL(jornada_ssp_start);
120 
121 /**
122  * jornada_ssp_end - disable mcu and turn off lock
123  *
124  */
125 void jornada_ssp_end(void)
126 {
127         GPSR = GPIO_GPIO25;
128         spin_unlock_irqrestore(&jornada_ssp_lock, jornada_ssp_flags);
129         return;
130 };
131 EXPORT_SYMBOL(jornada_ssp_end);
132 
133 static int 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 doesn't 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 }
202 
203 module_init(jornada_ssp_init);
204 

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