ptp: Added a brand new class driver for ptp clocks.

This patch adds an infrastructure for hardware clocks that implement
IEEE 1588, the Precision Time Protocol (PTP). A class driver offers a
registration method to particular hardware clock drivers. Each clock is
presented as a standard POSIX clock.

The ancillary clock features are exposed in two different ways, via
the sysfs and by a character device.

Signed-off-by: Richard Cochran <richard.cochran@omicron.at>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: David S. Miller <davem@davemloft.net>
Signed-off-by: John Stultz <john.stultz@linaro.org>

drivers/ptp/ptp_chardev.c

@@ -0,0 +1,159 @@
+/*
+ * PTP 1588 clock support - character device implementation.
+ *
+ * Copyright (C) 2010 OMICRON electronics GmbH
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation; either version 2 of the License, or
+ *  (at your option) any later version.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License
+ *  along with this program; if not, write to the Free Software
+ *  Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+ */
+#include <linux/module.h>
+#include <linux/posix-clock.h>
+#include <linux/poll.h>
+#include <linux/sched.h>
+
+#include "ptp_private.h"
+
+int ptp_open(struct posix_clock *pc, fmode_t fmode)
+{
+	return 0;
+}
+
+long ptp_ioctl(struct posix_clock *pc, unsigned int cmd, unsigned long arg)
+{
+	struct ptp_clock_caps caps;
+	struct ptp_clock_request req;
+	struct ptp_clock *ptp = container_of(pc, struct ptp_clock, clock);
+	struct ptp_clock_info *ops = ptp->info;
+	int enable, err = 0;
+
+	switch (cmd) {
+
+	case PTP_CLOCK_GETCAPS:
+		memset(&caps, 0, sizeof(caps));
+		caps.max_adj = ptp->info->max_adj;
+		caps.n_alarm = ptp->info->n_alarm;
+		caps.n_ext_ts = ptp->info->n_ext_ts;
+		caps.n_per_out = ptp->info->n_per_out;
+		caps.pps = ptp->info->pps;
+		err = copy_to_user((void __user *)arg, &caps, sizeof(caps));
+		break;
+
+	case PTP_EXTTS_REQUEST:
+		if (copy_from_user(&req.extts, (void __user *)arg,
+				   sizeof(req.extts))) {
+			err = -EFAULT;
+			break;
+		}
+		if (req.extts.index >= ops->n_ext_ts) {
+			err = -EINVAL;
+			break;
+		}
+		req.type = PTP_CLK_REQ_EXTTS;
+		enable = req.extts.flags & PTP_ENABLE_FEATURE ? 1 : 0;
+		err = ops->enable(ops, &req, enable);
+		break;
+
+	case PTP_PEROUT_REQUEST:
+		if (copy_from_user(&req.perout, (void __user *)arg,
+				   sizeof(req.perout))) {
+			err = -EFAULT;
+			break;
+		}
+		if (req.perout.index >= ops->n_per_out) {
+			err = -EINVAL;
+			break;
+		}
+		req.type = PTP_CLK_REQ_PEROUT;
+		enable = req.perout.period.sec || req.perout.period.nsec;
+		err = ops->enable(ops, &req, enable);
+		break;
+
+	case PTP_ENABLE_PPS:
+		if (!capable(CAP_SYS_TIME))
+			return -EPERM;
+		req.type = PTP_CLK_REQ_PPS;
+		enable = arg ? 1 : 0;
+		err = ops->enable(ops, &req, enable);
+		break;
+
+	default:
+		err = -ENOTTY;
+		break;
+	}
+	return err;
+}
+
+unsigned int ptp_poll(struct posix_clock *pc, struct file *fp, poll_table *wait)
+{
+	struct ptp_clock *ptp = container_of(pc, struct ptp_clock, clock);
+
+	poll_wait(fp, &ptp->tsev_wq, wait);
+
+	return queue_cnt(&ptp->tsevq) ? POLLIN : 0;
+}
+
+ssize_t ptp_read(struct posix_clock *pc,
+		 uint rdflags, char __user *buf, size_t cnt)
+{
+	struct ptp_clock *ptp = container_of(pc, struct ptp_clock, clock);
+	struct timestamp_event_queue *queue = &ptp->tsevq;
+	struct ptp_extts_event event[PTP_BUF_TIMESTAMPS];
+	unsigned long flags;
+	size_t qcnt, i;
+
+	if (cnt % sizeof(struct ptp_extts_event) != 0)
+		return -EINVAL;
+
+	if (cnt > sizeof(event))
+		cnt = sizeof(event);
+
+	cnt = cnt / sizeof(struct ptp_extts_event);
+
+	if (mutex_lock_interruptible(&ptp->tsevq_mux))
+		return -ERESTARTSYS;
+
+	if (wait_event_interruptible(ptp->tsev_wq,
+				     ptp->defunct || queue_cnt(queue))) {
+		mutex_unlock(&ptp->tsevq_mux);
+		return -ERESTARTSYS;
+	}
+
+	if (ptp->defunct)
+		return -ENODEV;
+
+	spin_lock_irqsave(&queue->lock, flags);
+
+	qcnt = queue_cnt(queue);
+
+	if (cnt > qcnt)
+		cnt = qcnt;
+
+	for (i = 0; i < cnt; i++) {
+		event[i] = queue->buf[queue->head];
+		queue->head = (queue->head + 1) % PTP_MAX_TIMESTAMPS;
+	}
+
+	spin_unlock_irqrestore(&queue->lock, flags);
+
+	cnt = cnt * sizeof(struct ptp_extts_event);
+
+	mutex_unlock(&ptp->tsevq_mux);
+
+	if (copy_to_user(buf, event, cnt)) {
+		mutex_unlock(&ptp->tsevq_mux);
+		return -EFAULT;
+	}
+
+	return cnt;
+}