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 */
jornada_ssp_reverse(u8 byte)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 */
jornada_ssp_byte(u8 byte)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 */
jornada_ssp_inout(u8 byte)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 */
jornada_ssp_start(void)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 */
jornada_ssp_end(void)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
jornada_ssp_probe(struct platform_device * dev)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
jornada_ssp_remove(struct platform_device * dev)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
jornada_ssp_init(void)197 static int __init jornada_ssp_init(void)
198 {
199 return platform_driver_register(&jornadassp_driver);
200 }
201
202 module_init(jornada_ssp_init);
203