aboutsummaryrefslogtreecommitdiff
path: root/arch/arm/mach-sa1100/ssp.c
blob: 06206ceb312ef5e4e0f79f274470ab3a0293003f (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
/*
 *  linux/arch/arm/mach-sa1100/ssp.c
 *
 *  Copyright (C) 2003 Russell King.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 *
 *  Generic SSP driver.  This provides the generic core for simple
 *  IO-based SSP applications.
 */
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/sched.h>
#include <linux/errno.h>
#include <linux/interrupt.h>
#include <linux/ioport.h>
#include <linux/init.h>

#include <asm/io.h>
#include <asm/irq.h>
#include <asm/hardware.h>
#include <asm/hardware/ssp.h>

#define TIMEOUT 100000

static irqreturn_t ssp_interrupt(int irq, void *dev_id)
{
	unsigned int status = Ser4SSSR;

	if (status & SSSR_ROR)
		printk(KERN_WARNING "SSP: receiver overrun\n");

	Ser4SSSR = SSSR_ROR;

	return status ? IRQ_HANDLED : IRQ_NONE;
}

/**
 * ssp_write_word - write a word to the SSP port
 * @data: 16-bit, MSB justified data to write.
 *
 * Wait for a free entry in the SSP transmit FIFO, and write a data
 * word to the SSP port.  Wait for the SSP port to start sending
 * the data.
 *
 * The caller is expected to perform the necessary locking.
 *
 * Returns:
 *   %-ETIMEDOUT	timeout occurred
 *   0			success
 */
int ssp_write_word(u16 data)
{
	int timeout = TIMEOUT;

	while (!(Ser4SSSR & SSSR_TNF)) {
	        if (!--timeout)
	        	return -ETIMEDOUT;
		cpu_relax();
	}

	Ser4SSDR = data;

	timeout = TIMEOUT;
	while (!(Ser4SSSR & SSSR_BSY)) {
	        if (!--timeout)
	        	return -ETIMEDOUT;
		cpu_relax();
	}

	return 0;
}

/**
 * ssp_read_word - read a word from the SSP port
 *
 * Wait for a data word in the SSP receive FIFO, and return the
 * received data.  Data is LSB justified.
 *
 * Note: Currently, if data is not expected to be received, this
 * function will wait for ever.
 *
 * The caller is expected to perform the necessary locking.
 *
 * Returns:
 *   %-ETIMEDOUT	timeout occurred
 *   16-bit data	success
 */
int ssp_read_word(u16 *data)
{
	int timeout = TIMEOUT;

	while (!(Ser4SSSR & SSSR_RNE)) {
	        if (!--timeout)
	        	return -ETIMEDOUT;
		cpu_relax();
	}

	*data = (u16)Ser4SSDR;

	return 0;
}

/**
 * ssp_flush - flush the transmit and receive FIFOs
 *
 * Wait for the SSP to idle, and ensure that the receive FIFO
 * is empty.
 *
 * The caller is expected to perform the necessary locking.
 *
 * Returns:
 *   %-ETIMEDOUT	timeout occurred
 *   0			success
 */
int ssp_flush(void)
{
	int timeout = TIMEOUT * 2;

	do {
		while (Ser4SSSR & SSSR_RNE) {
		        if (!--timeout)
		        	return -ETIMEDOUT;
			(void) Ser4SSDR;
		}
	        if (!--timeout)
	        	return -ETIMEDOUT;
	} while (Ser4SSSR & SSSR_BSY);

	return 0;
}

/**
 * ssp_enable - enable the SSP port
 *
 * Turn on the SSP port.
 */
void ssp_enable(void)
{
	Ser4SSCR0 |= SSCR0_SSE;
}

/**
 * ssp_disable - shut down the SSP port
 *
 * Turn off the SSP port, optionally powering it down.
 */
void ssp_disable(void)
{
	Ser4SSCR0 &= ~SSCR0_SSE;
}

/**
 * ssp_save_state - save the SSP configuration
 * @ssp: pointer to structure to save SSP configuration
 *
 * Save the configured SSP state for suspend.
 */
void ssp_save_state(struct ssp_state *ssp)
{
	ssp->cr0 = Ser4SSCR0;
	ssp->cr1 = Ser4SSCR1;

	Ser4SSCR0 &= ~SSCR0_SSE;
}

/**
 * ssp_restore_state - restore a previously saved SSP configuration
 * @ssp: pointer to configuration saved by ssp_save_state
 *
 * Restore the SSP configuration saved previously by ssp_save_state.
 */
void ssp_restore_state(struct ssp_state *ssp)
{
	Ser4SSSR = SSSR_ROR;

	Ser4SSCR0 = ssp->cr0 & ~SSCR0_SSE;
	Ser4SSCR1 = ssp->cr1;
	Ser4SSCR0 = ssp->cr0;
}

/**
 * ssp_init - setup the SSP port
 *
 * initialise and claim resources for the SSP port.
 *
 * Returns:
 *   %-ENODEV	if the SSP port is unavailable
 *   %-EBUSY	if the resources are already in use
 *   %0		on success
 */
int ssp_init(void)
{
	int ret;

	if (!(PPAR & PPAR_SPR) && (Ser4MCCR0 & MCCR0_MCE))
		return -ENODEV;

	if (!request_mem_region(__PREG(Ser4SSCR0), 0x18, "SSP")) {
		return -EBUSY;
	}

	Ser4SSSR = SSSR_ROR;

	ret = request_irq(IRQ_Ser4SSP, ssp_interrupt, 0, "SSP", NULL);
	if (ret)
		goto out_region;

	return 0;

 out_region:
	release_mem_region(__PREG(Ser4SSCR0), 0x18);
	return ret;
}

/**
 * ssp_exit - undo the effects of ssp_init
 *
 * release and free resources for the SSP port.
 */
void ssp_exit(void)
{
	Ser4SSCR0 &= ~SSCR0_SSE;

	free_irq(IRQ_Ser4SSP, NULL);
	release_mem_region(__PREG(Ser4SSCR0), 0x18);
}

MODULE_AUTHOR("Russell King");
MODULE_DESCRIPTION("SA11x0 SSP PIO driver");
MODULE_LICENSE("GPL");

EXPORT_SYMBOL(ssp_write_word);
EXPORT_SYMBOL(ssp_read_word);
EXPORT_SYMBOL(ssp_flush);
EXPORT_SYMBOL(ssp_enable);
EXPORT_SYMBOL(ssp_disable);
EXPORT_SYMBOL(ssp_save_state);
EXPORT_SYMBOL(ssp_restore_state);
EXPORT_SYMBOL(ssp_init);
EXPORT_SYMBOL(ssp_exit);