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