1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 *  arch/arm/mac-sa1100/jornada720_ssp.c
4 *
5 *  Copyright (C) 2006/2007 Kristoffer Ericson <Kristoffer.Ericson@gmail.com>
6 *   Copyright (C) 2006 Filip Zyzniewski <filip.zyzniewski@tefnet.pl>
7 *
8 *  SSP driver for the HP Jornada 710/720/728
9 */
10
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>
18#include <linux/io.h>
19
20#include <mach/hardware.h>
21#include <mach/jornada720.h>
22#include <asm/hardware/ssp.h>
23
24static DEFINE_SPINLOCK(jornada_ssp_lock);
25static unsigned long jornada_ssp_flags;
26
27/**
28 * jornada_ssp_reverse - reverses input byte
29 * @byte: input byte to reverse
30 *
31 * we need to reverse all data we receive from the mcu due to its physical location
32 * returns : 01110111 -> 11101110
33 */
34inline u8 jornada_ssp_reverse(u8 byte)
35{
36	return
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) |
44		((0x01 & byte) << 7);
45};
46EXPORT_SYMBOL(jornada_ssp_reverse);
47
48/**
49 * jornada_ssp_byte - waits for ready ssp bus and sends byte
50 * @byte: input byte to transmit
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 */
58int 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};
78EXPORT_SYMBOL(jornada_ssp_byte);
79
80/**
81 * jornada_ssp_inout - decide if input is command or trading byte
82 * @byte: input byte to send (may be %TXDUMMY)
83 *
84 * returns : (jornada_ssp_byte(byte)) on success
85 *         : %-ETIMEDOUT on timeout failure
86 */
87int 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};
106EXPORT_SYMBOL(jornada_ssp_inout);
107
108/**
109 * jornada_ssp_start - enable mcu
110 *
111 */
112void 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};
119EXPORT_SYMBOL(jornada_ssp_start);
120
121/**
122 * jornada_ssp_end - disable mcu and turn off lock
123 *
124 */
125void jornada_ssp_end(void)
126{
127	GPSR = GPIO_GPIO25;
128	spin_unlock_irqrestore(&jornada_ssp_lock, jornada_ssp_flags);
129	return;
130};
131EXPORT_SYMBOL(jornada_ssp_end);
132
133static 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
181static void 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};
188
189struct platform_driver jornadassp_driver = {
190	.probe	= jornada_ssp_probe,
191	.remove_new = jornada_ssp_remove,
192	.driver	= {
193		.name	= "jornada_ssp",
194	},
195};
196
197static int __init jornada_ssp_init(void)
198{
199	return platform_driver_register(&jornadassp_driver);
200}
201
202module_init(jornada_ssp_init);
203