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