drivers/pps/kapi.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  * kernel API
   4  *
   5  * Copyright (C) 2005-2009   Rodolfo Giometti <giometti@linux.it>
   6  */
   7
   8 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
   9
  10 #include <linux/kernel.h>
  11 #include <linux/module.h>
  12 #include <linux/init.h>
  13 #include <linux/sched.h>
  14 #include <linux/time.h>
  15 #include <linux/timex.h>
  16 #include <linux/spinlock.h>
  17 #include <linux/fs.h>
  18 #include <linux/pps_kernel.h>
  19 #include <linux/slab.h>
  20
  21 #include "kc.h"
  22
  23 /*
  24  * Local functions
  25  */
  26
  27 static void pps_add_offset(struct pps_ktime *ts, struct pps_ktime *offset)
  28 {
  29         ts->nsec += offset->nsec;
  30         while (ts->nsec >= NSEC_PER_SEC) {
  31                 ts->nsec -= NSEC_PER_SEC;
  32                 ts->sec++;
  33         }
  34         while (ts->nsec < 0) {
  35                 ts->nsec += NSEC_PER_SEC;
  36                 ts->sec--;
  37         }
  38         ts->sec += offset->sec;
  39 }
  40
  41 static void pps_echo_client_default(struct pps_device *pps, int event,
  42                 void *data)
  43 {
  44         dev_info(pps->dev, "echo %s %s\n",
  45                 event & PPS_CAPTUREASSERT ? "assert" : "",
  46                 event & PPS_CAPTURECLEAR ? "clear" : "");
  47 }
  48
  49 /*
  50  * Exported functions
  51  */
  52
  53 /* pps_register_source - add a PPS source in the system
  54  * @info: the PPS info struct
  55  * @default_params: the default PPS parameters of the new source
  56  *
  57  * This function is used to add a new PPS source in the system. The new
  58  * source is described by info's fields and it will have, as default PPS
  59  * parameters, the ones specified into default_params.
  60  *
  61  * The function returns, in case of success, the PPS device. Otherwise
  62  * ERR_PTR(errno).
  63  */
  64
  65 struct pps_device *pps_register_source(struct pps_source_info *info,
  66                 int default_params)
  67 {
  68         struct pps_device *pps;
  69         int err;
  70
  71         /* Sanity checks */
  72         if ((info->mode & default_params) != default_params) {
  73                 pr_err("%s: unsupported default parameters\n",
  74                                         info->name);
  75                 err = -EINVAL;
  76                 goto pps_register_source_exit;
  77         }
  78         if ((info->mode & (PPS_TSFMT_TSPEC | PPS_TSFMT_NTPFP)) == 0) {
  79                 pr_err("%s: unspecified time format\n",
  80                                         info->name);
  81                 err = -EINVAL;
  82                 goto pps_register_source_exit;
  83         }
  84
  85         /* Allocate memory for the new PPS source struct */
  86         pps = kzalloc(sizeof(struct pps_device), GFP_KERNEL);
  87         if (pps == NULL) {
  88                 err = -ENOMEM;
  89                 goto pps_register_source_exit;
  90         }
  91
  92         /* These initializations must be done before calling idr_alloc()
  93          * in order to avoid reces into pps_event().
  94          */
  95         pps->params.api_version = PPS_API_VERS;
  96         pps->params.mode = default_params;
  97         pps->info = *info;
  98
  99         /* check for default echo function */
 100         if ((pps->info.mode & (PPS_ECHOASSERT | PPS_ECHOCLEAR)) &&
 101                         pps->info.echo == NULL)
 102                 pps->info.echo = pps_echo_client_default;
 103
 104         init_waitqueue_head(&pps->queue);
 105         spin_lock_init(&pps->lock);
 106
 107         /* Create the char device */
 108         err = pps_register_cdev(pps);
 109         if (err < 0) {
 110                 pr_err("%s: unable to create char device\n",
 111                                         info->name);
 112                 goto kfree_pps;
 113         }
 114
 115         dev_info(pps->dev, "new PPS source %s\n", info->name);
 116
 117         return pps;
 118
 119 kfree_pps:
 120         kfree(pps);
 121
 122 pps_register_source_exit:
 123         pr_err("%s: unable to register source\n", info->name);
 124
 125         return ERR_PTR(err);
 126 }
 127 EXPORT_SYMBOL(pps_register_source);
 128
 129 /* pps_unregister_source - remove a PPS source from the system
 130  * @pps: the PPS source
 131  *
 132  * This function is used to remove a previously registered PPS source from
 133  * the system.
 134  */
 135
 136 void pps_unregister_source(struct pps_device *pps)
 137 {
 138         pps_kc_remove(pps);
 139         pps_unregister_cdev(pps);
 140
 141         /* don't have to kfree(pps) here because it will be done on
 142          * device destruction */
 143 }
 144 EXPORT_SYMBOL(pps_unregister_source);
 145
 146 /* pps_event - register a PPS event into the system
 147  * @pps: the PPS device
 148  * @ts: the event timestamp
 149  * @event: the event type
 150  * @data: userdef pointer
 151  *
 152  * This function is used by each PPS client in order to register a new
 153  * PPS event into the system (it's usually called inside an IRQ handler).
 154  *
 155  * If an echo function is associated with the PPS device it will be called
 156  * as:
 157  *      pps->info.echo(pps, event, data);
 158  */
 159 void pps_event(struct pps_device *pps, struct pps_event_time *ts, int event,
 160                 void *data)
 161 {
 162         unsigned long flags;
 163         int captured = 0;
 164         struct pps_ktime ts_real = { .sec = 0, .nsec = 0, .flags = 0 };
 165
 166         /* check event type */
 167         BUG_ON((event & (PPS_CAPTUREASSERT | PPS_CAPTURECLEAR)) == 0);
 168
 169         dev_dbg(pps->dev, "PPS event at %lld.%09ld\n",
 170                         (s64)ts->ts_real.tv_sec, ts->ts_real.tv_nsec);
 171
 172         timespec_to_pps_ktime(&ts_real, ts->ts_real);
 173
 174         spin_lock_irqsave(&pps->lock, flags);
 175
 176         /* Must call the echo function? */
 177         if ((pps->params.mode & (PPS_ECHOASSERT | PPS_ECHOCLEAR)))
 178                 pps->info.echo(pps, event, data);
 179
 180         /* Check the event */
 181         pps->current_mode = pps->params.mode;
 182         if (event & pps->params.mode & PPS_CAPTUREASSERT) {
 183                 /* We have to add an offset? */
 184                 if (pps->params.mode & PPS_OFFSETASSERT)
 185                         pps_add_offset(&ts_real,
 186                                         &pps->params.assert_off_tu);
 187
 188                 /* Save the time stamp */
 189                 pps->assert_tu = ts_real;
 190                 pps->assert_sequence++;
 191                 dev_dbg(pps->dev, "capture assert seq #%u\n",
 192                         pps->assert_sequence);
 193
 194                 captured = ~0;
 195         }
 196         if (event & pps->params.mode & PPS_CAPTURECLEAR) {
 197                 /* We have to add an offset? */
 198                 if (pps->params.mode & PPS_OFFSETCLEAR)
 199                         pps_add_offset(&ts_real,
 200                                         &pps->params.clear_off_tu);
 201
 202                 /* Save the time stamp */
 203                 pps->clear_tu = ts_real;
 204                 pps->clear_sequence++;
 205                 dev_dbg(pps->dev, "capture clear seq #%u\n",
 206                         pps->clear_sequence);
 207
 208                 captured = ~0;
 209         }
 210
 211         pps_kc_event(pps, ts, event);
 212
 213         /* Wake up if captured something */
 214         if (captured) {
 215                 pps->last_ev++;
 216                 wake_up_interruptible_all(&pps->queue);
 217
 218                 kill_fasync(&pps->async_queue, SIGIO, POLL_IN);
 219         }
 220
 221         spin_unlock_irqrestore(&pps->lock, flags);
 222 }
 223 EXPORT_SYMBOL(pps_event);