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
ssp_interrupt(int irq,void * dev_id)28 static 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 */
ssp_write_word(u16 data)54 int 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 */
ssp_read_word(u16 * data)91 int 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 */
ssp_flush(void)118 int 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 */
ssp_enable(void)140 void 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 */
ssp_disable(void)150 void 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 */
ssp_save_state(struct ssp_state * ssp)161 void 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 */
ssp_restore_state(struct ssp_state * ssp)175 void 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 */
ssp_init(void)194 int 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 */
ssp_exit(void)223 void ssp_exit(void)
224 {
225 Ser4SSCR0 &= ~SSCR0_SSE;
226
227 free_irq(IRQ_Ser4SSP, NULL);
228 release_mem_region(__PREG(Ser4SSCR0), 0x18);
229 }
230
231 MODULE_AUTHOR("Russell King");
232 MODULE_DESCRIPTION("SA11x0 SSP PIO driver");
233 MODULE_LICENSE("GPL");
234
235 EXPORT_SYMBOL(ssp_write_word);
236 EXPORT_SYMBOL(ssp_read_word);
237 EXPORT_SYMBOL(ssp_flush);
238 EXPORT_SYMBOL(ssp_enable);
239 EXPORT_SYMBOL(ssp_disable);
240 EXPORT_SYMBOL(ssp_save_state);
241 EXPORT_SYMBOL(ssp_restore_state);
242 EXPORT_SYMBOL(ssp_init);
243 EXPORT_SYMBOL(ssp_exit);
244