arch/arm/mach-pxa/ssp.c

   1 /*
   2  *  linux/arch/arm/mach-pxa/ssp.c
   3  *
   4  *  based on linux/arch/arm/mach-sa1100/ssp.c by Russell King
   5  *
   6  *  Copyright (C) 2003 Russell King.
   7  *  Copyright (C) 2003 Wolfson Microelectronics PLC
   8  *
   9  * This program is free software; you can redistribute it and/or modify
  10  * it under the terms of the GNU General Public License version 2 as
  11  * published by the Free Software Foundation.
  12  *
  13  *  PXA2xx SSP driver.  This provides the generic core for simple
  14  *  IO-based SSP applications and allows easy port setup for DMA access.
  15  *
  16  *  Author: Liam Girdwood <liam.girdwood@wolfsonmicro.com>
  17  *
  18  *  Revision history:
  19  *   22nd Aug 2003 Initial version.
  20  *   20th Dec 2004 Added ssp_config for changing port config without
  21  *                 closing the port.
  22  *    4th Aug 2005 Added option to disable irq handler registration and
  23  *                 cleaned up irq and clock detection.
  24  */
  25
  26 #include <linux/module.h>
  27 #include <linux/kernel.h>
  28 #include <linux/sched.h>
  29 #include <linux/slab.h>
  30 #include <linux/errno.h>
  31 #include <linux/interrupt.h>
  32 #include <linux/ioport.h>
  33 #include <linux/init.h>
  34 #include <linux/mutex.h>
  35 #include <asm/io.h>
  36 #include <asm/irq.h>
  37 #include <asm/hardware.h>
  38 #include <asm/arch/ssp.h>
  39 #include <asm/arch/pxa-regs.h>
  40
  41 #define PXA_SSP_PORTS   3
  42
  43 #define TIMEOUT 100000
  44
  45 struct ssp_info_ {
  46         int irq;
  47         u32 clock;
  48 };
  49
  50 /*
  51  * SSP port clock and IRQ settings
  52  */
  53 static const struct ssp_info_ ssp_info[PXA_SSP_PORTS] = {
  54 #if defined (CONFIG_PXA27x)
  55         {IRQ_SSP,       CKEN_SSP1},
  56         {IRQ_SSP2,      CKEN_SSP2},
  57         {IRQ_SSP3,      CKEN_SSP3},
  58 #else
  59         {IRQ_SSP,       CKEN_SSP},
  60         {IRQ_NSSP,      CKEN_NSSP},
  61         {IRQ_ASSP,      CKEN_ASSP},
  62 #endif
  63 };
  64
  65 static DEFINE_MUTEX(mutex);
  66 static int use_count[PXA_SSP_PORTS] = {0, 0, 0};
  67
  68 static irqreturn_t ssp_interrupt(int irq, void *dev_id)
  69 {
  70         struct ssp_dev *dev = (struct ssp_dev*) dev_id;
  71         unsigned int status = SSSR_P(dev->port);
  72
  73         SSSR_P(dev->port) = status; /* clear status bits */
  74
  75         if (status & SSSR_ROR)
  76                 printk(KERN_WARNING "SSP(%d): receiver overrun\n", dev->port);
  77
  78         if (status & SSSR_TUR)
  79                 printk(KERN_WARNING "SSP(%d): transmitter underrun\n", dev->port);
  80
  81         if (status & SSSR_BCE)
  82                 printk(KERN_WARNING "SSP(%d): bit count error\n", dev->port);
  83
  84         return IRQ_HANDLED;
  85 }
  86
  87 /**
  88  * ssp_write_word - write a word to the SSP port
  89  * @data: 32-bit, MSB justified data to write.
  90  *
  91  * Wait for a free entry in the SSP transmit FIFO, and write a data
  92  * word to the SSP port.
  93  *
  94  * The caller is expected to perform the necessary locking.
  95  *
  96  * Returns:
  97  *   %-ETIMEDOUT        timeout occurred
  98  *   0                  success
  99  */
 100 int ssp_write_word(struct ssp_dev *dev, u32 data)
 101 {
 102         int timeout = TIMEOUT;
 103
 104         while (!(SSSR_P(dev->port) & SSSR_TNF)) {
 105                 if (!--timeout)
 106                         return -ETIMEDOUT;
 107                 cpu_relax();
 108         }
 109
 110         SSDR_P(dev->port) = data;
 111
 112         return 0;
 113 }
 114
 115 /**
 116  * ssp_read_word - read a word from the SSP port
 117  *
 118  * Wait for a data word in the SSP receive FIFO, and return the
 119  * received data.  Data is LSB justified.
 120  *
 121  * Note: Currently, if data is not expected to be received, this
 122  * function will wait for ever.
 123  *
 124  * The caller is expected to perform the necessary locking.
 125  *
 126  * Returns:
 127  *   %-ETIMEDOUT        timeout occurred
 128  *   32-bit data        success
 129  */
 130 int ssp_read_word(struct ssp_dev *dev, u32 *data)
 131 {
 132         int timeout = TIMEOUT;
 133
 134         while (!(SSSR_P(dev->port) & SSSR_RNE)) {
 135                 if (!--timeout)
 136                         return -ETIMEDOUT;
 137                 cpu_relax();
 138         }
 139
 140         *data = SSDR_P(dev->port);
 141         return 0;
 142 }
 143
 144 /**
 145  * ssp_flush - flush the transmit and receive FIFOs
 146  *
 147  * Wait for the SSP to idle, and ensure that the receive FIFO
 148  * is empty.
 149  *
 150  * The caller is expected to perform the necessary locking.
 151  */
 152 int ssp_flush(struct ssp_dev *dev)
 153 {
 154         int timeout = TIMEOUT * 2;
 155
 156         do {
 157                 while (SSSR_P(dev->port) & SSSR_RNE) {
 158                         if (!--timeout)
 159                                 return -ETIMEDOUT;
 160                         (void) SSDR_P(dev->port);
 161                 }
 162                 if (!--timeout)
 163                         return -ETIMEDOUT;
 164         } while (SSSR_P(dev->port) & SSSR_BSY);
 165
 166         return 0;
 167 }
 168
 169 /**
 170  * ssp_enable - enable the SSP port
 171  *
 172  * Turn on the SSP port.
 173  */
 174 void ssp_enable(struct ssp_dev *dev)
 175 {
 176         SSCR0_P(dev->port) |= SSCR0_SSE;
 177 }
 178
 179 /**
 180  * ssp_disable - shut down the SSP port
 181  *
 182  * Turn off the SSP port, optionally powering it down.
 183  */
 184 void ssp_disable(struct ssp_dev *dev)
 185 {
 186         SSCR0_P(dev->port) &= ~SSCR0_SSE;
 187 }
 188
 189 /**
 190  * ssp_save_state - save the SSP configuration
 191  * @ssp: pointer to structure to save SSP configuration
 192  *
 193  * Save the configured SSP state for suspend.
 194  */
 195 void ssp_save_state(struct ssp_dev *dev, struct ssp_state *ssp)
 196 {
 197         ssp->cr0 = SSCR0_P(dev->port);
 198         ssp->cr1 = SSCR1_P(dev->port);
 199         ssp->to = SSTO_P(dev->port);
 200         ssp->psp = SSPSP_P(dev->port);
 201
 202         SSCR0_P(dev->port) &= ~SSCR0_SSE;
 203 }
 204
 205 /**
 206  * ssp_restore_state - restore a previously saved SSP configuration
 207  * @ssp: pointer to configuration saved by ssp_save_state
 208  *
 209  * Restore the SSP configuration saved previously by ssp_save_state.
 210  */
 211 void ssp_restore_state(struct ssp_dev *dev, struct ssp_state *ssp)
 212 {
 213         SSSR_P(dev->port) = SSSR_ROR | SSSR_TUR | SSSR_BCE;
 214
 215         SSCR0_P(dev->port) = ssp->cr0 & ~SSCR0_SSE;
 216         SSCR1_P(dev->port) = ssp->cr1;
 217         SSTO_P(dev->port) = ssp->to;
 218         SSPSP_P(dev->port) = ssp->psp;
 219
 220         SSCR0_P(dev->port) = ssp->cr0;
 221 }
 222
 223 /**
 224  * ssp_config - configure SSP port settings
 225  * @mode: port operating mode
 226  * @flags: port config flags
 227  * @psp_flags: port PSP config flags
 228  * @speed: port speed
 229  *
 230  * Port MUST be disabled by ssp_disable before making any config changes.
 231  */
 232 int ssp_config(struct ssp_dev *dev, u32 mode, u32 flags, u32 psp_flags, u32 speed)
 233 {
 234         dev->mode = mode;
 235         dev->flags = flags;
 236         dev->psp_flags = psp_flags;
 237         dev->speed = speed;
 238
 239         /* set up port type, speed, port settings */
 240         SSCR0_P(dev->port) = (dev->speed | dev->mode);
 241         SSCR1_P(dev->port) = dev->flags;
 242         SSPSP_P(dev->port) = dev->psp_flags;
 243
 244         return 0;
 245 }
 246
 247 /**
 248  * ssp_init - setup the SSP port
 249  *
 250  * initialise and claim resources for the SSP port.
 251  *
 252  * Returns:
 253  *   %-ENODEV   if the SSP port is unavailable
 254  *   %-EBUSY    if the resources are already in use
 255  *   %0         on success
 256  */
 257 int ssp_init(struct ssp_dev *dev, u32 port, u32 init_flags)
 258 {
 259         int ret;
 260
 261         if (port > PXA_SSP_PORTS || port == 0)
 262                 return -ENODEV;
 263
 264         mutex_lock(&mutex);
 265         if (use_count[port - 1]) {
 266                 mutex_unlock(&mutex);
 267                 return -EBUSY;
 268         }
 269         use_count[port - 1]++;
 270
 271         if (!request_mem_region(__PREG(SSCR0_P(port)), 0x2c, "SSP")) {
 272                 use_count[port - 1]--;
 273                 mutex_unlock(&mutex);
 274                 return -EBUSY;
 275         }
 276         dev->port = port;
 277
 278         /* do we need to get irq */
 279         if (!(init_flags & SSP_NO_IRQ)) {
 280                 ret = request_irq(ssp_info[port-1].irq, ssp_interrupt,
 281                                 0, "SSP", dev);
 282                 if (ret)
 283                         goto out_region;
 284                 dev->irq = ssp_info[port-1].irq;
 285         } else
 286                 dev->irq = 0;
 287
 288         /* turn on SSP port clock */
 289         pxa_set_cken(ssp_info[port-1].clock, 1);
 290         mutex_unlock(&mutex);
 291         return 0;
 292
 293 out_region:
 294         release_mem_region(__PREG(SSCR0_P(port)), 0x2c);
 295         use_count[port - 1]--;
 296         mutex_unlock(&mutex);
 297         return ret;
 298 }
 299
 300 /**
 301  * ssp_exit - undo the effects of ssp_init
 302  *
 303  * release and free resources for the SSP port.
 304  */
 305 void ssp_exit(struct ssp_dev *dev)
 306 {
 307         mutex_lock(&mutex);
 308         SSCR0_P(dev->port) &= ~SSCR0_SSE;
 309
 310         if (dev->port > PXA_SSP_PORTS || dev->port == 0) {
 311                 printk(KERN_WARNING "SSP: tried to close invalid port\n");
 312                 mutex_unlock(&mutex);
 313                 return;
 314         }
 315
 316         pxa_set_cken(ssp_info[dev->port-1].clock, 0);
 317         if (dev->irq)
 318                 free_irq(dev->irq, dev);
 319         release_mem_region(__PREG(SSCR0_P(dev->port)), 0x2c);
 320         use_count[dev->port - 1]--;
 321         mutex_unlock(&mutex);
 322 }
 323
 324 EXPORT_SYMBOL(ssp_write_word);
 325 EXPORT_SYMBOL(ssp_read_word);
 326 EXPORT_SYMBOL(ssp_flush);
 327 EXPORT_SYMBOL(ssp_enable);
 328 EXPORT_SYMBOL(ssp_disable);
 329 EXPORT_SYMBOL(ssp_save_state);
 330 EXPORT_SYMBOL(ssp_restore_state);
 331 EXPORT_SYMBOL(ssp_init);
 332 EXPORT_SYMBOL(ssp_exit);
 333 EXPORT_SYMBOL(ssp_config);
 334
 335 MODULE_DESCRIPTION("PXA SSP driver");
 336 MODULE_AUTHOR("Liam Girdwood");
 337 MODULE_LICENSE("GPL");
 338