arch/arm/mach-sa1100/ssp.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  *  linux/arch/arm/mach-sa1100/ssp.c
   4  *
   5  *  Copyright (C) 2003 Russell King.
   6  *
   7  *  Generic SSP driver.  This provides the generic core for simple
   8  *  IO-based SSP applications.
   9  */
  10 #include <linux/module.h>
  11 #include <linux/kernel.h>
  12 #include <linux/sched.h>
  13 #include <linux/errno.h>
  14 #include <linux/interrupt.h>
  15 #include <linux/ioport.h>
  16 #include <linux/init.h>
  17 #include <linux/io.h>
  18
  19 #include <mach/hardware.h>
  20 #include <mach/irqs.h>
  21 #include <asm/hardware/ssp.h>
  22
  23 #define TIMEOUT 100000
  24
  25 static irqreturn_t ssp_interrupt(int irq, void *dev_id)
  26 {
  27         unsigned int status = Ser4SSSR;
  28
  29         if (status & SSSR_ROR)
  30                 printk(KERN_WARNING "SSP: receiver overrun\n");
  31
  32         Ser4SSSR = SSSR_ROR;
  33
  34         return status ? IRQ_HANDLED : IRQ_NONE;
  35 }
  36
  37 /**
  38  * ssp_write_word - write a word to the SSP port
  39  * @data: 16-bit, MSB justified data to write.
  40  *
  41  * Wait for a free entry in the SSP transmit FIFO, and write a data
  42  * word to the SSP port.  Wait for the SSP port to start sending
  43  * the data.
  44  *
  45  * The caller is expected to perform the necessary locking.
  46  *
  47  * Returns:
  48  *   %-ETIMEDOUT        timeout occurred
  49  *   0                  success
  50  */
  51 int ssp_write_word(u16 data)
  52 {
  53         int timeout = TIMEOUT;
  54
  55         while (!(Ser4SSSR & SSSR_TNF)) {
  56                 if (!--timeout)
  57                         return -ETIMEDOUT;
  58                 cpu_relax();
  59         }
  60
  61         Ser4SSDR = data;
  62
  63         timeout = TIMEOUT;
  64         while (!(Ser4SSSR & SSSR_BSY)) {
  65                 if (!--timeout)
  66                         return -ETIMEDOUT;
  67                 cpu_relax();
  68         }
  69
  70         return 0;
  71 }
  72
  73 /**
  74  * ssp_read_word - read a word from the SSP port
  75  *
  76  * Wait for a data word in the SSP receive FIFO, and return the
  77  * received data.  Data is LSB justified.
  78  *
  79  * Note: Currently, if data is not expected to be received, this
  80  * function will wait for ever.
  81  *
  82  * The caller is expected to perform the necessary locking.
  83  *
  84  * Returns:
  85  *   %-ETIMEDOUT        timeout occurred
  86  *   16-bit data        success
  87  */
  88 int ssp_read_word(u16 *data)
  89 {
  90         int timeout = TIMEOUT;
  91
  92         while (!(Ser4SSSR & SSSR_RNE)) {
  93                 if (!--timeout)
  94                         return -ETIMEDOUT;
  95                 cpu_relax();
  96         }
  97
  98         *data = (u16)Ser4SSDR;
  99
 100         return 0;
 101 }
 102
 103 /**
 104  * ssp_flush - flush the transmit and receive FIFOs
 105  *
 106  * Wait for the SSP to idle, and ensure that the receive FIFO
 107  * is empty.
 108  *
 109  * The caller is expected to perform the necessary locking.
 110  *
 111  * Returns:
 112  *   %-ETIMEDOUT        timeout occurred
 113  *   0                  success
 114  */
 115 int ssp_flush(void)
 116 {
 117         int timeout = TIMEOUT * 2;
 118
 119         do {
 120                 while (Ser4SSSR & SSSR_RNE) {
 121                         if (!--timeout)
 122                                 return -ETIMEDOUT;
 123                         (void) Ser4SSDR;
 124                 }
 125                 if (!--timeout)
 126                         return -ETIMEDOUT;
 127         } while (Ser4SSSR & SSSR_BSY);
 128
 129         return 0;
 130 }
 131
 132 /**
 133  * ssp_enable - enable the SSP port
 134  *
 135  * Turn on the SSP port.
 136  */
 137 void ssp_enable(void)
 138 {
 139         Ser4SSCR0 |= SSCR0_SSE;
 140 }
 141
 142 /**
 143  * ssp_disable - shut down the SSP port
 144  *
 145  * Turn off the SSP port, optionally powering it down.
 146  */
 147 void ssp_disable(void)
 148 {
 149         Ser4SSCR0 &= ~SSCR0_SSE;
 150 }
 151
 152 /**
 153  * ssp_save_state - save the SSP configuration
 154  * @ssp: pointer to structure to save SSP configuration
 155  *
 156  * Save the configured SSP state for suspend.
 157  */
 158 void ssp_save_state(struct ssp_state *ssp)
 159 {
 160         ssp->cr0 = Ser4SSCR0;
 161         ssp->cr1 = Ser4SSCR1;
 162
 163         Ser4SSCR0 &= ~SSCR0_SSE;
 164 }
 165
 166 /**
 167  * ssp_restore_state - restore a previously saved SSP configuration
 168  * @ssp: pointer to configuration saved by ssp_save_state
 169  *
 170  * Restore the SSP configuration saved previously by ssp_save_state.
 171  */
 172 void ssp_restore_state(struct ssp_state *ssp)
 173 {
 174         Ser4SSSR = SSSR_ROR;
 175
 176         Ser4SSCR0 = ssp->cr0 & ~SSCR0_SSE;
 177         Ser4SSCR1 = ssp->cr1;
 178         Ser4SSCR0 = ssp->cr0;
 179 }
 180
 181 /**
 182  * ssp_init - setup the SSP port
 183  *
 184  * initialise and claim resources for the SSP port.
 185  *
 186  * Returns:
 187  *   %-ENODEV   if the SSP port is unavailable
 188  *   %-EBUSY    if the resources are already in use
 189  *   %0         on success
 190  */
 191 int ssp_init(void)
 192 {
 193         int ret;
 194
 195         if (!(PPAR & PPAR_SPR) && (Ser4MCCR0 & MCCR0_MCE))
 196                 return -ENODEV;
 197
 198         if (!request_mem_region(__PREG(Ser4SSCR0), 0x18, "SSP")) {
 199                 return -EBUSY;
 200         }
 201
 202         Ser4SSSR = SSSR_ROR;
 203
 204         ret = request_irq(IRQ_Ser4SSP, ssp_interrupt, 0, "SSP", NULL);
 205         if (ret)
 206                 goto out_region;
 207
 208         return 0;
 209
 210  out_region:
 211         release_mem_region(__PREG(Ser4SSCR0), 0x18);
 212         return ret;
 213 }
 214
 215 /**
 216  * ssp_exit - undo the effects of ssp_init
 217  *
 218  * release and free resources for the SSP port.
 219  */
 220 void ssp_exit(void)
 221 {
 222         Ser4SSCR0 &= ~SSCR0_SSE;
 223
 224         free_irq(IRQ_Ser4SSP, NULL);
 225         release_mem_region(__PREG(Ser4SSCR0), 0x18);
 226 }
 227
 228 MODULE_AUTHOR("Russell King");
 229 MODULE_DESCRIPTION("SA11x0 SSP PIO driver");
 230 MODULE_LICENSE("GPL");
 231
 232 EXPORT_SYMBOL(ssp_write_word);
 233 EXPORT_SYMBOL(ssp_read_word);
 234 EXPORT_SYMBOL(ssp_flush);
 235 EXPORT_SYMBOL(ssp_enable);
 236 EXPORT_SYMBOL(ssp_disable);
 237 EXPORT_SYMBOL(ssp_save_state);
 238 EXPORT_SYMBOL(ssp_restore_state);
 239 EXPORT_SYMBOL(ssp_init);
 240 EXPORT_SYMBOL(ssp_exit);