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1da177e4 LT |
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> | |
fced80c7 | 20 | #include <linux/io.h> |
1da177e4 | 21 | |
a09e64fb | 22 | #include <mach/hardware.h> |
f314f33b | 23 | #include <mach/irqs.h> |
1da177e4 LT |
24 | #include <asm/hardware/ssp.h> |
25 | ||
8f1bf874 PS |
26 | #define TIMEOUT 100000 |
27 | ||
0cd61b68 | 28 | static irqreturn_t ssp_interrupt(int irq, void *dev_id) |
1da177e4 LT |
29 | { |
30 | unsigned int status = Ser4SSSR; | |
31 | ||
e8f2af17 | 32 | if (status & SSSR_ROR) |
1da177e4 | 33 | printk(KERN_WARNING "SSP: receiver overrun\n"); |
1da177e4 LT |
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: | |
8f1bf874 | 51 | * %-ETIMEDOUT timeout occurred |
1da177e4 LT |
52 | * 0 success |
53 | */ | |
54 | int ssp_write_word(u16 data) | |
55 | { | |
8f1bf874 PS |
56 | int timeout = TIMEOUT; |
57 | ||
58 | while (!(Ser4SSSR & SSSR_TNF)) { | |
59 | if (!--timeout) | |
60 | return -ETIMEDOUT; | |
1da177e4 | 61 | cpu_relax(); |
8f1bf874 | 62 | } |
1da177e4 LT |
63 | |
64 | Ser4SSDR = data; | |
65 | ||
8f1bf874 PS |
66 | timeout = TIMEOUT; |
67 | while (!(Ser4SSSR & SSSR_BSY)) { | |
68 | if (!--timeout) | |
69 | return -ETIMEDOUT; | |
1da177e4 | 70 | cpu_relax(); |
8f1bf874 | 71 | } |
1da177e4 LT |
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: | |
8f1bf874 | 88 | * %-ETIMEDOUT timeout occurred |
1da177e4 LT |
89 | * 16-bit data success |
90 | */ | |
8f1bf874 | 91 | int ssp_read_word(u16 *data) |
1da177e4 | 92 | { |
8f1bf874 PS |
93 | int timeout = TIMEOUT; |
94 | ||
95 | while (!(Ser4SSSR & SSSR_RNE)) { | |
96 | if (!--timeout) | |
97 | return -ETIMEDOUT; | |
1da177e4 | 98 | cpu_relax(); |
8f1bf874 PS |
99 | } |
100 | ||
101 | *data = (u16)Ser4SSDR; | |
1da177e4 | 102 | |
8f1bf874 | 103 | return 0; |
1da177e4 LT |
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. | |
8f1bf874 PS |
113 | * |
114 | * Returns: | |
115 | * %-ETIMEDOUT timeout occurred | |
116 | * 0 success | |
1da177e4 | 117 | */ |
8f1bf874 | 118 | int ssp_flush(void) |
1da177e4 | 119 | { |
8f1bf874 PS |
120 | int timeout = TIMEOUT * 2; |
121 | ||
1da177e4 LT |
122 | do { |
123 | while (Ser4SSSR & SSSR_RNE) { | |
8f1bf874 PS |
124 | if (!--timeout) |
125 | return -ETIMEDOUT; | |
1da177e4 LT |
126 | (void) Ser4SSDR; |
127 | } | |
8f1bf874 PS |
128 | if (!--timeout) |
129 | return -ETIMEDOUT; | |
1da177e4 | 130 | } while (Ser4SSSR & SSSR_BSY); |
8f1bf874 PS |
131 | |
132 | return 0; | |
1da177e4 LT |
133 | } |
134 | ||
135 | /** | |
136 | * ssp_enable - enable the SSP port | |
137 | * | |
138 | * Turn on the SSP port. | |
139 | */ | |
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 | */ | |
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 | */ | |
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 | */ | |
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 | */ | |
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 | */ | |
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); |