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Linux/arch/arm/mach-sa1100/ssp.c

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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 #include <linux/io.h>
 21 
 22 #include <asm/irq.h>
 23 #include <mach/hardware.h>
 24 #include <asm/hardware/ssp.h>
 25 
 26 #define TIMEOUT 100000
 27 
 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  */
 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  */
 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  */
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  */
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);
244 

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