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 
24 static DEFINE_SPINLOCK(jornada_ssp_lock);
25 static unsigned long jornada_ssp_flags;
26 
27 /**
28  * jornada_ssp_reverse - reverses input byte
29  *
30  * we need to reverse all data we receive from the mcu due to its physical location
31  * returns : 01110111 -> 11101110
32  */
jornada_ssp_reverse(u8 byte)33 inline u8 jornada_ssp_reverse(u8 byte)
34 {
35 	return
36 		((0x80 & byte) >> 7) |
37 		((0x40 & byte) >> 5) |
38 		((0x20 & byte) >> 3) |
39 		((0x10 & byte) >> 1) |
40 		((0x08 & byte) << 1) |
41 		((0x04 & byte) << 3) |
42 		((0x02 & byte) << 5) |
43 		((0x01 & byte) << 7);
44 };
45 EXPORT_SYMBOL(jornada_ssp_reverse);
46 
47 /**
48  * jornada_ssp_byte - waits for ready ssp bus and sends byte
49  *
50  * waits for fifo buffer to clear and then transmits, if it doesn't then we will
51  * timeout after <timeout> rounds. Needs mcu running before its called.
52  *
53  * returns : %mcu output on success
54  *	   : %-ETIMEDOUT on timeout
55  */
jornada_ssp_byte(u8 byte)56 int jornada_ssp_byte(u8 byte)
57 {
58 	int timeout = 400000;
59 	u16 ret;
60 
61 	while ((GPLR & GPIO_GPIO10)) {
62 		if (!--timeout) {
63 			printk(KERN_WARNING "SSP: timeout while waiting for transmit\n");
64 			return -ETIMEDOUT;
65 		}
66 		cpu_relax();
67 	}
68 
69 	ret = jornada_ssp_reverse(byte) << 8;
70 
71 	ssp_write_word(ret);
72 	ssp_read_word(&ret);
73 
74 	return jornada_ssp_reverse(ret);
75 };
76 EXPORT_SYMBOL(jornada_ssp_byte);
77 
78 /**
79  * jornada_ssp_inout - decide if input is command or trading byte
80  *
81  * returns : (jornada_ssp_byte(byte)) on success
82  *         : %-ETIMEDOUT on timeout failure
83  */
jornada_ssp_inout(u8 byte)84 int jornada_ssp_inout(u8 byte)
85 {
86 	int ret, i;
87 
88 	/* true means command byte */
89 	if (byte != TXDUMMY) {
90 		ret = jornada_ssp_byte(byte);
91 		/* Proper return to commands is TxDummy */
92 		if (ret != TXDUMMY) {
93 			for (i = 0; i < 256; i++)/* flushing bus */
94 				if (jornada_ssp_byte(TXDUMMY) == -1)
95 					break;
96 			return -ETIMEDOUT;
97 		}
98 	} else /* Exchange TxDummy for data */
99 		ret = jornada_ssp_byte(TXDUMMY);
100 
101 	return ret;
102 };
103 EXPORT_SYMBOL(jornada_ssp_inout);
104 
105 /**
106  * jornada_ssp_start - enable mcu
107  *
108  */
jornada_ssp_start(void)109 void jornada_ssp_start(void)
110 {
111 	spin_lock_irqsave(&jornada_ssp_lock, jornada_ssp_flags);
112 	GPCR = GPIO_GPIO25;
113 	udelay(50);
114 	return;
115 };
116 EXPORT_SYMBOL(jornada_ssp_start);
117 
118 /**
119  * jornada_ssp_end - disable mcu and turn off lock
120  *
121  */
jornada_ssp_end(void)122 void jornada_ssp_end(void)
123 {
124 	GPSR = GPIO_GPIO25;
125 	spin_unlock_irqrestore(&jornada_ssp_lock, jornada_ssp_flags);
126 	return;
127 };
128 EXPORT_SYMBOL(jornada_ssp_end);
129 
jornada_ssp_probe(struct platform_device * dev)130 static int jornada_ssp_probe(struct platform_device *dev)
131 {
132 	int ret;
133 
134 	GPSR = GPIO_GPIO25;
135 
136 	ret = ssp_init();
137 
138 	/* worked fine, lets not bother with anything else */
139 	if (!ret) {
140 		printk(KERN_INFO "SSP: device initialized with irq\n");
141 		return ret;
142 	}
143 
144 	printk(KERN_WARNING "SSP: initialization failed, trying non-irq solution \n");
145 
146 	/* init of Serial 4 port */
147 	Ser4MCCR0 = 0;
148 	Ser4SSCR0 = 0x0387;
149 	Ser4SSCR1 = 0x18;
150 
151 	/* clear out any left over data */
152 	ssp_flush();
153 
154 	/* enable MCU */
155 	jornada_ssp_start();
156 
157 	/* see if return value makes sense */
158 	ret = jornada_ssp_inout(GETBRIGHTNESS);
159 
160 	/* seems like it worked, just feed it with TxDummy to get rid of data */
161 	if (ret == TXDUMMY)
162 		jornada_ssp_inout(TXDUMMY);
163 
164 	jornada_ssp_end();
165 
166 	/* failed, lets just kill everything */
167 	if (ret == -ETIMEDOUT) {
168 		printk(KERN_WARNING "SSP: attempts failed, bailing\n");
169 		ssp_exit();
170 		return -ENODEV;
171 	}
172 
173 	/* all fine */
174 	printk(KERN_INFO "SSP: device initialized\n");
175 	return 0;
176 };
177 
jornada_ssp_remove(struct platform_device * dev)178 static int jornada_ssp_remove(struct platform_device *dev)
179 {
180 	/* Note that this doesn't actually remove the driver, since theres nothing to remove
181 	 * It just makes sure everything is turned off */
182 	GPSR = GPIO_GPIO25;
183 	ssp_exit();
184 	return 0;
185 };
186 
187 struct platform_driver jornadassp_driver = {
188 	.probe	= jornada_ssp_probe,
189 	.remove	= jornada_ssp_remove,
190 	.driver	= {
191 		.name	= "jornada_ssp",
192 	},
193 };
194 
jornada_ssp_init(void)195 static int __init jornada_ssp_init(void)
196 {
197 	return platform_driver_register(&jornadassp_driver);
198 }
199 
200 module_init(jornada_ssp_init);
201