1/*
2 *  linux/arch/arm/mach-sa1100/ssp.c
3 *
4 *  Copyright (C) 2003 Russell King.
5 *
6 * This program is free software; you can redistribute it and/or modify
7 * it under the terms of the GNU General Public License version 2 as
8 * published by the Free Software Foundation.
9 *
10 *  Generic SSP driver.  This provides the generic core for simple
11 *  IO-based SSP applications.
12 */
13#include <linux/module.h>
14#include <linux/kernel.h>
15#include <linux/sched.h>
16#include <linux/errno.h>
17#include <linux/interrupt.h>
18#include <linux/ioport.h>
19#include <linux/init.h>
20#include <linux/io.h>
21
22#include <mach/hardware.h>
23#include <mach/irqs.h>
24#include <asm/hardware/ssp.h>
25
26#define TIMEOUT 100000
27
28static irqreturn_t ssp_interrupt(int irq, void *dev_id)
29{
30	unsigned int status = Ser4SSSR;
31
32	if (status & SSSR_ROR)
33		printk(KERN_WARNING "SSP: receiver overrun\n");
34
35	Ser4SSSR = SSSR_ROR;
36
37	return status ? IRQ_HANDLED : IRQ_NONE;
38}
39
40/**
41 * ssp_write_word - write a word to the SSP port
42 * @data: 16-bit, MSB justified data to write.
43 *
44 * Wait for a free entry in the SSP transmit FIFO, and write a data
45 * word to the SSP port.  Wait for the SSP port to start sending
46 * the data.
47 *
48 * The caller is expected to perform the necessary locking.
49 *
50 * Returns:
51 *   %-ETIMEDOUT	timeout occurred
52 *   0			success
53 */
54int ssp_write_word(u16 data)
55{
56	int timeout = TIMEOUT;
57
58	while (!(Ser4SSSR & SSSR_TNF)) {
59	        if (!--timeout)
60	        	return -ETIMEDOUT;
61		cpu_relax();
62	}
63
64	Ser4SSDR = data;
65
66	timeout = TIMEOUT;
67	while (!(Ser4SSSR & SSSR_BSY)) {
68	        if (!--timeout)
69	        	return -ETIMEDOUT;
70		cpu_relax();
71	}
72
73	return 0;
74}
75
76/**
77 * ssp_read_word - read a word from the SSP port
78 *
79 * Wait for a data word in the SSP receive FIFO, and return the
80 * received data.  Data is LSB justified.
81 *
82 * Note: Currently, if data is not expected to be received, this
83 * function will wait for ever.
84 *
85 * The caller is expected to perform the necessary locking.
86 *
87 * Returns:
88 *   %-ETIMEDOUT	timeout occurred
89 *   16-bit data	success
90 */
91int ssp_read_word(u16 *data)
92{
93	int timeout = TIMEOUT;
94
95	while (!(Ser4SSSR & SSSR_RNE)) {
96	        if (!--timeout)
97	        	return -ETIMEDOUT;
98		cpu_relax();
99	}
100
101	*data = (u16)Ser4SSDR;
102
103	return 0;
104}
105
106/**
107 * ssp_flush - flush the transmit and receive FIFOs
108 *
109 * Wait for the SSP to idle, and ensure that the receive FIFO
110 * is empty.
111 *
112 * The caller is expected to perform the necessary locking.
113 *
114 * Returns:
115 *   %-ETIMEDOUT	timeout occurred
116 *   0			success
117 */
118int ssp_flush(void)
119{
120	int timeout = TIMEOUT * 2;
121
122	do {
123		while (Ser4SSSR & SSSR_RNE) {
124		        if (!--timeout)
125		        	return -ETIMEDOUT;
126			(void) Ser4SSDR;
127		}
128	        if (!--timeout)
129	        	return -ETIMEDOUT;
130	} while (Ser4SSSR & SSSR_BSY);
131
132	return 0;
133}
134
135/**
136 * ssp_enable - enable the SSP port
137 *
138 * Turn on the SSP port.
139 */
140void ssp_enable(void)
141{
142	Ser4SSCR0 |= SSCR0_SSE;
143}
144
145/**
146 * ssp_disable - shut down the SSP port
147 *
148 * Turn off the SSP port, optionally powering it down.
149 */
150void ssp_disable(void)
151{
152	Ser4SSCR0 &= ~SSCR0_SSE;
153}
154
155/**
156 * ssp_save_state - save the SSP configuration
157 * @ssp: pointer to structure to save SSP configuration
158 *
159 * Save the configured SSP state for suspend.
160 */
161void ssp_save_state(struct ssp_state *ssp)
162{
163	ssp->cr0 = Ser4SSCR0;
164	ssp->cr1 = Ser4SSCR1;
165
166	Ser4SSCR0 &= ~SSCR0_SSE;
167}
168
169/**
170 * ssp_restore_state - restore a previously saved SSP configuration
171 * @ssp: pointer to configuration saved by ssp_save_state
172 *
173 * Restore the SSP configuration saved previously by ssp_save_state.
174 */
175void ssp_restore_state(struct ssp_state *ssp)
176{
177	Ser4SSSR = SSSR_ROR;
178
179	Ser4SSCR0 = ssp->cr0 & ~SSCR0_SSE;
180	Ser4SSCR1 = ssp->cr1;
181	Ser4SSCR0 = ssp->cr0;
182}
183
184/**
185 * ssp_init - setup the SSP port
186 *
187 * initialise and claim resources for the SSP port.
188 *
189 * Returns:
190 *   %-ENODEV	if the SSP port is unavailable
191 *   %-EBUSY	if the resources are already in use
192 *   %0		on success
193 */
194int ssp_init(void)
195{
196	int ret;
197
198	if (!(PPAR & PPAR_SPR) && (Ser4MCCR0 & MCCR0_MCE))
199		return -ENODEV;
200
201	if (!request_mem_region(__PREG(Ser4SSCR0), 0x18, "SSP")) {
202		return -EBUSY;
203	}
204
205	Ser4SSSR = SSSR_ROR;
206
207	ret = request_irq(IRQ_Ser4SSP, ssp_interrupt, 0, "SSP", NULL);
208	if (ret)
209		goto out_region;
210
211	return 0;
212
213 out_region:
214	release_mem_region(__PREG(Ser4SSCR0), 0x18);
215	return ret;
216}
217
218/**
219 * ssp_exit - undo the effects of ssp_init
220 *
221 * release and free resources for the SSP port.
222 */
223void ssp_exit(void)
224{
225	Ser4SSCR0 &= ~SSCR0_SSE;
226
227	free_irq(IRQ_Ser4SSP, NULL);
228	release_mem_region(__PREG(Ser4SSCR0), 0x18);
229}
230
231MODULE_AUTHOR("Russell King");
232MODULE_DESCRIPTION("SA11x0 SSP PIO driver");
233MODULE_LICENSE("GPL");
234
235EXPORT_SYMBOL(ssp_write_word);
236EXPORT_SYMBOL(ssp_read_word);
237EXPORT_SYMBOL(ssp_flush);
238EXPORT_SYMBOL(ssp_enable);
239EXPORT_SYMBOL(ssp_disable);
240EXPORT_SYMBOL(ssp_save_state);
241EXPORT_SYMBOL(ssp_restore_state);
242EXPORT_SYMBOL(ssp_init);
243EXPORT_SYMBOL(ssp_exit);
244