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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> | |
20 | ||
21 | #include <asm/io.h> | |
22 | #include <asm/irq.h> | |
23 | #include <asm/hardware.h> | |
24 | #include <asm/hardware/ssp.h> | |
25 | ||
8f1bf874 PS |
26 | #define TIMEOUT 100000 |
27 | ||
1da177e4 LT |
28 | static irqreturn_t ssp_interrupt(int irq, void *dev_id, struct pt_regs *regs) |
29 | { | |
30 | unsigned int status = Ser4SSSR; | |
31 | ||
32 | if (status & SSSR_ROR) { | |
33 | printk(KERN_WARNING "SSP: receiver overrun\n"); | |
34 | } | |
35 | ||
36 | Ser4SSSR = SSSR_ROR; | |
37 | ||
38 | return status ? IRQ_HANDLED : IRQ_NONE; | |
39 | } | |
40 | ||
41 | /** | |
42 | * ssp_write_word - write a word to the SSP port | |
43 | * @data: 16-bit, MSB justified data to write. | |
44 | * | |
45 | * Wait for a free entry in the SSP transmit FIFO, and write a data | |
46 | * word to the SSP port. Wait for the SSP port to start sending | |
47 | * the data. | |
48 | * | |
49 | * The caller is expected to perform the necessary locking. | |
50 | * | |
51 | * Returns: | |
8f1bf874 | 52 | * %-ETIMEDOUT timeout occurred |
1da177e4 LT |
53 | * 0 success |
54 | */ | |
55 | int ssp_write_word(u16 data) | |
56 | { | |
8f1bf874 PS |
57 | int timeout = TIMEOUT; |
58 | ||
59 | while (!(Ser4SSSR & SSSR_TNF)) { | |
60 | if (!--timeout) | |
61 | return -ETIMEDOUT; | |
1da177e4 | 62 | cpu_relax(); |
8f1bf874 | 63 | } |
1da177e4 LT |
64 | |
65 | Ser4SSDR = data; | |
66 | ||
8f1bf874 PS |
67 | timeout = TIMEOUT; |
68 | while (!(Ser4SSSR & SSSR_BSY)) { | |
69 | if (!--timeout) | |
70 | return -ETIMEDOUT; | |
1da177e4 | 71 | cpu_relax(); |
8f1bf874 | 72 | } |
1da177e4 LT |
73 | |
74 | return 0; | |
75 | } | |
76 | ||
77 | /** | |
78 | * ssp_read_word - read a word from the SSP port | |
79 | * | |
80 | * Wait for a data word in the SSP receive FIFO, and return the | |
81 | * received data. Data is LSB justified. | |
82 | * | |
83 | * Note: Currently, if data is not expected to be received, this | |
84 | * function will wait for ever. | |
85 | * | |
86 | * The caller is expected to perform the necessary locking. | |
87 | * | |
88 | * Returns: | |
8f1bf874 | 89 | * %-ETIMEDOUT timeout occurred |
1da177e4 LT |
90 | * 16-bit data success |
91 | */ | |
8f1bf874 | 92 | int ssp_read_word(u16 *data) |
1da177e4 | 93 | { |
8f1bf874 PS |
94 | int timeout = TIMEOUT; |
95 | ||
96 | while (!(Ser4SSSR & SSSR_RNE)) { | |
97 | if (!--timeout) | |
98 | return -ETIMEDOUT; | |
1da177e4 | 99 | cpu_relax(); |
8f1bf874 PS |
100 | } |
101 | ||
102 | *data = (u16)Ser4SSDR; | |
1da177e4 | 103 | |
8f1bf874 | 104 | return 0; |
1da177e4 LT |
105 | } |
106 | ||
107 | /** | |
108 | * ssp_flush - flush the transmit and receive FIFOs | |
109 | * | |
110 | * Wait for the SSP to idle, and ensure that the receive FIFO | |
111 | * is empty. | |
112 | * | |
113 | * The caller is expected to perform the necessary locking. | |
8f1bf874 PS |
114 | * |
115 | * Returns: | |
116 | * %-ETIMEDOUT timeout occurred | |
117 | * 0 success | |
1da177e4 | 118 | */ |
8f1bf874 | 119 | int ssp_flush(void) |
1da177e4 | 120 | { |
8f1bf874 PS |
121 | int timeout = TIMEOUT * 2; |
122 | ||
1da177e4 LT |
123 | do { |
124 | while (Ser4SSSR & SSSR_RNE) { | |
8f1bf874 PS |
125 | if (!--timeout) |
126 | return -ETIMEDOUT; | |
1da177e4 LT |
127 | (void) Ser4SSDR; |
128 | } | |
8f1bf874 PS |
129 | if (!--timeout) |
130 | return -ETIMEDOUT; | |
1da177e4 | 131 | } while (Ser4SSSR & SSSR_BSY); |
8f1bf874 PS |
132 | |
133 | return 0; | |
1da177e4 LT |
134 | } |
135 | ||
136 | /** | |
137 | * ssp_enable - enable the SSP port | |
138 | * | |
139 | * Turn on the SSP port. | |
140 | */ | |
141 | void ssp_enable(void) | |
142 | { | |
143 | Ser4SSCR0 |= SSCR0_SSE; | |
144 | } | |
145 | ||
146 | /** | |
147 | * ssp_disable - shut down the SSP port | |
148 | * | |
149 | * Turn off the SSP port, optionally powering it down. | |
150 | */ | |
151 | void ssp_disable(void) | |
152 | { | |
153 | Ser4SSCR0 &= ~SSCR0_SSE; | |
154 | } | |
155 | ||
156 | /** | |
157 | * ssp_save_state - save the SSP configuration | |
158 | * @ssp: pointer to structure to save SSP configuration | |
159 | * | |
160 | * Save the configured SSP state for suspend. | |
161 | */ | |
162 | void ssp_save_state(struct ssp_state *ssp) | |
163 | { | |
164 | ssp->cr0 = Ser4SSCR0; | |
165 | ssp->cr1 = Ser4SSCR1; | |
166 | ||
167 | Ser4SSCR0 &= ~SSCR0_SSE; | |
168 | } | |
169 | ||
170 | /** | |
171 | * ssp_restore_state - restore a previously saved SSP configuration | |
172 | * @ssp: pointer to configuration saved by ssp_save_state | |
173 | * | |
174 | * Restore the SSP configuration saved previously by ssp_save_state. | |
175 | */ | |
176 | void ssp_restore_state(struct ssp_state *ssp) | |
177 | { | |
178 | Ser4SSSR = SSSR_ROR; | |
179 | ||
180 | Ser4SSCR0 = ssp->cr0 & ~SSCR0_SSE; | |
181 | Ser4SSCR1 = ssp->cr1; | |
182 | Ser4SSCR0 = ssp->cr0; | |
183 | } | |
184 | ||
185 | /** | |
186 | * ssp_init - setup the SSP port | |
187 | * | |
188 | * initialise and claim resources for the SSP port. | |
189 | * | |
190 | * Returns: | |
191 | * %-ENODEV if the SSP port is unavailable | |
192 | * %-EBUSY if the resources are already in use | |
193 | * %0 on success | |
194 | */ | |
195 | int ssp_init(void) | |
196 | { | |
197 | int ret; | |
198 | ||
199 | if (!(PPAR & PPAR_SPR) && (Ser4MCCR0 & MCCR0_MCE)) | |
200 | return -ENODEV; | |
201 | ||
202 | if (!request_mem_region(__PREG(Ser4SSCR0), 0x18, "SSP")) { | |
203 | return -EBUSY; | |
204 | } | |
205 | ||
206 | Ser4SSSR = SSSR_ROR; | |
207 | ||
208 | ret = request_irq(IRQ_Ser4SSP, ssp_interrupt, 0, "SSP", NULL); | |
209 | if (ret) | |
210 | goto out_region; | |
211 | ||
212 | return 0; | |
213 | ||
214 | out_region: | |
215 | release_mem_region(__PREG(Ser4SSCR0), 0x18); | |
216 | return ret; | |
217 | } | |
218 | ||
219 | /** | |
220 | * ssp_exit - undo the effects of ssp_init | |
221 | * | |
222 | * release and free resources for the SSP port. | |
223 | */ | |
224 | void ssp_exit(void) | |
225 | { | |
226 | Ser4SSCR0 &= ~SSCR0_SSE; | |
227 | ||
228 | free_irq(IRQ_Ser4SSP, NULL); | |
229 | release_mem_region(__PREG(Ser4SSCR0), 0x18); | |
230 | } | |
231 | ||
232 | MODULE_AUTHOR("Russell King"); | |
233 | MODULE_DESCRIPTION("SA11x0 SSP PIO driver"); | |
234 | MODULE_LICENSE("GPL"); | |
235 | ||
236 | EXPORT_SYMBOL(ssp_write_word); | |
237 | EXPORT_SYMBOL(ssp_read_word); | |
238 | EXPORT_SYMBOL(ssp_flush); | |
239 | EXPORT_SYMBOL(ssp_enable); | |
240 | EXPORT_SYMBOL(ssp_disable); | |
241 | EXPORT_SYMBOL(ssp_save_state); | |
242 | EXPORT_SYMBOL(ssp_restore_state); | |
243 | EXPORT_SYMBOL(ssp_init); | |
244 | EXPORT_SYMBOL(ssp_exit); |