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 <asm/io.h>
  35 #include <asm/irq.h>
  36 #include <asm/hardware.h>
  37 #include <asm/arch/ssp.h>
  38 #include <asm/arch/pxa-regs.h>
  39
  40 #define PXA_SSP_PORTS   3
  41
  42 struct ssp_info_ {
  43         int irq;
  44         u32 clock;
  45 };
  46
  47 /*
  48  * SSP port clock and IRQ settings
  49  */
  50 static const struct ssp_info_ ssp_info[PXA_SSP_PORTS] = {
  51 #if defined (CONFIG_PXA27x)
  52         {IRQ_SSP,       CKEN23_SSP1},
  53         {IRQ_SSP2,      CKEN3_SSP2},
  54         {IRQ_SSP3,      CKEN4_SSP3},
  55 #else
  56         {IRQ_SSP,       CKEN3_SSP},
  57         {IRQ_NSSP,      CKEN9_NSSP},
  58         {IRQ_ASSP,      CKEN10_ASSP},
  59 #endif
  60 };
  61
  62 static DECLARE_MUTEX(sem);
  63 static int use_count[PXA_SSP_PORTS] = {0, 0, 0};
  64
  65 static irqreturn_t ssp_interrupt(int irq, void *dev_id, struct pt_regs *regs)
  66 {
  67         struct ssp_dev *dev = (struct ssp_dev*) dev_id;
  68         unsigned int status = SSSR_P(dev->port);
  69
  70         SSSR_P(dev->port) = status; /* clear status bits */
  71
  72         if (status & SSSR_ROR)
  73                 printk(KERN_WARNING "SSP(%d): receiver overrun\n", dev->port);
  74
  75         if (status & SSSR_TUR)
  76                 printk(KERN_WARNING "SSP(%d): transmitter underrun\n", dev->port);
  77
  78         if (status & SSSR_BCE)
  79                 printk(KERN_WARNING "SSP(%d): bit count error\n", dev->port);
  80
  81         return IRQ_HANDLED;
  82 }
  83
  84 /**
  85  * ssp_write_word - write a word to the SSP port
  86  * @data: 32-bit, MSB justified data to write.
  87  *
  88  * Wait for a free entry in the SSP transmit FIFO, and write a data
  89  * word to the SSP port.
  90  *
  91  * The caller is expected to perform the necessary locking.
  92  *
  93  * Returns:
  94  *   %-ETIMEDOUT        timeout occurred (for future)
  95  *   0                  success
  96  */
  97 int ssp_write_word(struct ssp_dev *dev, u32 data)
  98 {
  99         while (!(SSSR_P(dev->port) & SSSR_TNF))
 100                 cpu_relax();
 101
 102         SSDR_P(dev->port) = data;
 103
 104         return 0;
 105 }
 106
 107 /**
 108  * ssp_read_word - read a word from the SSP port
 109  *
 110  * Wait for a data word in the SSP receive FIFO, and return the
 111  * received data.  Data is LSB justified.
 112  *
 113  * Note: Currently, if data is not expected to be received, this
 114  * function will wait for ever.
 115  *
 116  * The caller is expected to perform the necessary locking.
 117  *
 118  * Returns:
 119  *   %-ETIMEDOUT        timeout occurred (for future)
 120  *   32-bit data        success
 121  */
 122 int ssp_read_word(struct ssp_dev *dev)
 123 {
 124         while (!(SSSR_P(dev->port) & SSSR_RNE))
 125                 cpu_relax();
 126
 127         return SSDR_P(dev->port);
 128 }
 129
 130 /**
 131  * ssp_flush - flush the transmit and receive FIFOs
 132  *
 133  * Wait for the SSP to idle, and ensure that the receive FIFO
 134  * is empty.
 135  *
 136  * The caller is expected to perform the necessary locking.
 137  */
 138 void ssp_flush(struct ssp_dev *dev)
 139 {
 140         do {
 141                 while (SSSR_P(dev->port) & SSSR_RNE) {
 142                         (void) SSDR_P(dev->port);
 143                 }
 144         } while (SSSR_P(dev->port) & SSSR_BSY);
 145 }
 146
 147 /**
 148  * ssp_enable - enable the SSP port
 149  *
 150  * Turn on the SSP port.
 151  */
 152 void ssp_enable(struct ssp_dev *dev)
 153 {
 154         SSCR0_P(dev->port) |= SSCR0_SSE;
 155 }
 156
 157 /**
 158  * ssp_disable - shut down the SSP port
 159  *
 160  * Turn off the SSP port, optionally powering it down.
 161  */
 162 void ssp_disable(struct ssp_dev *dev)
 163 {
 164         SSCR0_P(dev->port) &= ~SSCR0_SSE;
 165 }
 166
 167 /**
 168  * ssp_save_state - save the SSP configuration
 169  * @ssp: pointer to structure to save SSP configuration
 170  *
 171  * Save the configured SSP state for suspend.
 172  */
 173 void ssp_save_state(struct ssp_dev *dev, struct ssp_state *ssp)
 174 {
 175         ssp->cr0 = SSCR0_P(dev->port);
 176         ssp->cr1 = SSCR1_P(dev->port);
 177         ssp->to = SSTO_P(dev->port);
 178         ssp->psp = SSPSP_P(dev->port);
 179
 180         SSCR0_P(dev->port) &= ~SSCR0_SSE;
 181 }
 182
 183 /**
 184  * ssp_restore_state - restore a previously saved SSP configuration
 185  * @ssp: pointer to configuration saved by ssp_save_state
 186  *
 187  * Restore the SSP configuration saved previously by ssp_save_state.
 188  */
 189 void ssp_restore_state(struct ssp_dev *dev, struct ssp_state *ssp)
 190 {
 191         SSSR_P(dev->port) = SSSR_ROR | SSSR_TUR | SSSR_BCE;
 192
 193         SSCR0_P(dev->port) = ssp->cr0 & ~SSCR0_SSE;
 194         SSCR1_P(dev->port) = ssp->cr1;
 195         SSTO_P(dev->port) = ssp->to;
 196         SSPSP_P(dev->port) = ssp->psp;
 197
 198         SSCR0_P(dev->port) = ssp->cr0;
 199 }
 200
 201 /**
 202  * ssp_config - configure SSP port settings
 203  * @mode: port operating mode
 204  * @flags: port config flags
 205  * @psp_flags: port PSP config flags
 206  * @speed: port speed
 207  *
 208  * Port MUST be disabled by ssp_disable before making any config changes.
 209  */
 210 int ssp_config(struct ssp_dev *dev, u32 mode, u32 flags, u32 psp_flags, u32 speed)
 211 {
 212         dev->mode = mode;
 213         dev->flags = flags;
 214         dev->psp_flags = psp_flags;
 215         dev->speed = speed;
 216
 217         /* set up port type, speed, port settings */
 218         SSCR0_P(dev->port) = (dev->speed | dev->mode);
 219         SSCR1_P(dev->port) = dev->flags;
 220         SSPSP_P(dev->port) = dev->psp_flags;
 221
 222         return 0;
 223 }
 224
 225 /**
 226  * ssp_init - setup the SSP port
 227  *
 228  * initialise and claim resources for the SSP port.
 229  *
 230  * Returns:
 231  *   %-ENODEV   if the SSP port is unavailable
 232  *   %-EBUSY    if the resources are already in use
 233  *   %0         on success
 234  */
 235 int ssp_init(struct ssp_dev *dev, u32 port, u32 init_flags)
 236 {
 237         int ret;
 238
 239         if (port > PXA_SSP_PORTS || port == 0)
 240                 return -ENODEV;
 241
 242         down(&sem);
 243         if (use_count[port - 1]) {
 244                 up(&sem);
 245                 return -EBUSY;
 246         }
 247         use_count[port - 1]++;
 248
 249         if (!request_mem_region(__PREG(SSCR0_P(port)), 0x2c, "SSP")) {
 250                 use_count[port - 1]--;
 251                 up(&sem);
 252                 return -EBUSY;
 253         }
 254         dev->port = port;
 255
 256         /* do we need to get irq */
 257         if (!(init_flags & SSP_NO_IRQ)) {
 258                 ret = request_irq(ssp_info[port-1].irq, ssp_interrupt,
 259                                 0, "SSP", dev);
 260                 if (ret)
 261                         goto out_region;
 262                 dev->irq = ssp_info[port-1].irq;
 263         } else
 264                 dev->irq = 0;
 265
 266         /* turn on SSP port clock */
 267         pxa_set_cken(ssp_info[port-1].clock, 1);
 268         up(&sem);
 269         return 0;
 270
 271 out_region:
 272         release_mem_region(__PREG(SSCR0_P(port)), 0x2c);
 273         use_count[port - 1]--;
 274         up(&sem);
 275         return ret;
 276 }
 277
 278 /**
 279  * ssp_exit - undo the effects of ssp_init
 280  *
 281  * release and free resources for the SSP port.
 282  */
 283 void ssp_exit(struct ssp_dev *dev)
 284 {
 285         down(&sem);
 286         SSCR0_P(dev->port) &= ~SSCR0_SSE;
 287
 288         if (dev->port > PXA_SSP_PORTS || dev->port == 0) {
 289                 printk(KERN_WARNING "SSP: tried to close invalid port\n");
 290                 return;
 291         }
 292
 293         pxa_set_cken(ssp_info[dev->port-1].clock, 0);
 294         if (dev->irq)
 295                 free_irq(dev->irq, dev);
 296         release_mem_region(__PREG(SSCR0_P(dev->port)), 0x2c);
 297         use_count[dev->port - 1]--;
 298         up(&sem);
 299 }
 300
 301 EXPORT_SYMBOL(ssp_write_word);
 302 EXPORT_SYMBOL(ssp_read_word);
 303 EXPORT_SYMBOL(ssp_flush);
 304 EXPORT_SYMBOL(ssp_enable);
 305 EXPORT_SYMBOL(ssp_disable);
 306 EXPORT_SYMBOL(ssp_save_state);
 307 EXPORT_SYMBOL(ssp_restore_state);
 308 EXPORT_SYMBOL(ssp_init);
 309 EXPORT_SYMBOL(ssp_exit);
 310 EXPORT_SYMBOL(ssp_config);
 311
 312 MODULE_DESCRIPTION("PXA SSP driver");
 313 MODULE_AUTHOR("Liam Girdwood");
 314 MODULE_LICENSE("GPL");
 315