1 // SPDX-License-Identifier: GPL-2.0-only
3 * arch/arm/mac-sa1100/jornada720_ssp.c
5 * Copyright (C) 2006/2007 Kristoffer Ericson <Kristoffer.Ericson@gmail.com>
6 * Copyright (C) 2006 Filip Zyzniewski <filip.zyzniewski@tefnet.pl>
8 * SSP driver for the HP Jornada 710/720/728
11 #include <linux/delay.h>
12 #include <linux/errno.h>
13 #include <linux/init.h>
14 #include <linux/kernel.h>
15 #include <linux/module.h>
16 #include <linux/platform_device.h>
17 #include <linux/sched.h>
20 #include <mach/hardware.h>
21 #include <mach/jornada720.h>
22 #include <asm/hardware/ssp.h>
24 static DEFINE_SPINLOCK(jornada_ssp_lock);
25 static unsigned long jornada_ssp_flags;
28 * jornada_ssp_reverse - reverses input byte
29 * @byte: input byte to reverse
31 * we need to reverse all data we receive from the mcu due to its physical location
32 * returns : 01110111 -> 11101110
34 inline u8 jornada_ssp_reverse(u8 byte)
37 ((0x80 & byte) >> 7) |
38 ((0x40 & byte) >> 5) |
39 ((0x20 & byte) >> 3) |
40 ((0x10 & byte) >> 1) |
41 ((0x08 & byte) << 1) |
42 ((0x04 & byte) << 3) |
43 ((0x02 & byte) << 5) |
46 EXPORT_SYMBOL(jornada_ssp_reverse);
49 * jornada_ssp_byte - waits for ready ssp bus and sends byte
50 * @byte: input byte to transmit
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.
55 * returns : %mcu output on success
56 * : %-ETIMEDOUT on timeout
58 int jornada_ssp_byte(u8 byte)
63 while ((GPLR & GPIO_GPIO10)) {
65 printk(KERN_WARNING "SSP: timeout while waiting for transmit\n");
71 ret = jornada_ssp_reverse(byte) << 8;
76 return jornada_ssp_reverse(ret);
78 EXPORT_SYMBOL(jornada_ssp_byte);
81 * jornada_ssp_inout - decide if input is command or trading byte
82 * @byte: input byte to send (may be %TXDUMMY)
84 * returns : (jornada_ssp_byte(byte)) on success
85 * : %-ETIMEDOUT on timeout failure
87 int jornada_ssp_inout(u8 byte)
91 /* true means command byte */
92 if (byte != TXDUMMY) {
93 ret = jornada_ssp_byte(byte);
94 /* Proper return to commands is TxDummy */
96 for (i = 0; i < 256; i++)/* flushing bus */
97 if (jornada_ssp_byte(TXDUMMY) == -1)
101 } else /* Exchange TxDummy for data */
102 ret = jornada_ssp_byte(TXDUMMY);
106 EXPORT_SYMBOL(jornada_ssp_inout);
109 * jornada_ssp_start - enable mcu
112 void jornada_ssp_start(void)
114 spin_lock_irqsave(&jornada_ssp_lock, jornada_ssp_flags);
119 EXPORT_SYMBOL(jornada_ssp_start);
122 * jornada_ssp_end - disable mcu and turn off lock
125 void jornada_ssp_end(void)
128 spin_unlock_irqrestore(&jornada_ssp_lock, jornada_ssp_flags);
131 EXPORT_SYMBOL(jornada_ssp_end);
133 static int jornada_ssp_probe(struct platform_device *dev)
141 /* worked fine, lets not bother with anything else */
143 printk(KERN_INFO "SSP: device initialized with irq\n");
147 printk(KERN_WARNING "SSP: initialization failed, trying non-irq solution \n");
149 /* init of Serial 4 port */
154 /* clear out any left over data */
160 /* see if return value makes sense */
161 ret = jornada_ssp_inout(GETBRIGHTNESS);
163 /* seems like it worked, just feed it with TxDummy to get rid of data */
165 jornada_ssp_inout(TXDUMMY);
169 /* failed, lets just kill everything */
170 if (ret == -ETIMEDOUT) {
171 printk(KERN_WARNING "SSP: attempts failed, bailing\n");
177 printk(KERN_INFO "SSP: device initialized\n");
181 static int jornada_ssp_remove(struct platform_device *dev)
183 /* Note that this doesn't actually remove the driver, since theres nothing to remove
184 * It just makes sure everything is turned off */
190 struct platform_driver jornadassp_driver = {
191 .probe = jornada_ssp_probe,
192 .remove = jornada_ssp_remove,
194 .name = "jornada_ssp",
198 static int __init jornada_ssp_init(void)
200 return platform_driver_register(&jornadassp_driver);
203 module_init(jornada_ssp_init);