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  * @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  */
jornada_ssp_reverse(u8 byte)34 inline 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 };
46 EXPORT_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  */
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  * @byte: input byte to send (may be %TXDUMMY)
83  *
84  * returns : (jornada_ssp_byte(byte)) on success
85  *         : %-ETIMEDOUT on timeout failure
86  */
jornada_ssp_inout(u8 byte)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  */
jornada_ssp_start(void)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  */
jornada_ssp_end(void)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 
jornada_ssp_probe(struct platform_device * dev)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 
jornada_ssp_remove(struct platform_device * dev)181 static 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 
189 struct platform_driver jornadassp_driver = {
190 	.probe	= jornada_ssp_probe,
191 	.remove_new = 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