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>

1 files changed, 230 insertions, 0 deletions

diff --git a/drivers/ptp/ptp_sysfs.c b/drivers/ptp/ptp_sysfs.c
new file mode 100644
index 000000000000..2f93926ac976
--- /dev/null
+++ b/drivers/ptp/ptp_sysfs.c
@@ -0,0 +1,230 @@
+/*
+ * PTP 1588 clock support - sysfs interface.
+ *
+ * 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/capability.h>
+
+#include "ptp_private.h"
+
+static ssize_t clock_name_show(struct device *dev,
+                               struct device_attribute *attr, char *page)
+{
+        struct ptp_clock *ptp = dev_get_drvdata(dev);
+        return snprintf(page, PAGE_SIZE-1, "%s\n", ptp->info->name);
+}
+
+#define PTP_SHOW_INT(name)                                              \
+static ssize_t name##_show(struct device *dev,                          \
+                           struct device_attribute *attr, char *page)   \
+{                                                                       \
+        struct ptp_clock *ptp = dev_get_drvdata(dev);                   \
+        return snprintf(page, PAGE_SIZE-1, "%d\n", ptp->info->name);    \
+}
+
+PTP_SHOW_INT(max_adj);
+PTP_SHOW_INT(n_alarm);
+PTP_SHOW_INT(n_ext_ts);
+PTP_SHOW_INT(n_per_out);
+PTP_SHOW_INT(pps);
+
+#define PTP_RO_ATTR(_var, _name) {                              \
+        .attr   = { .name = __stringify(_name), .mode = 0444 }, \
+        .show   = _var##_show,                                  \
+}
+
+struct device_attribute ptp_dev_attrs[] = {
+        PTP_RO_ATTR(clock_name, clock_name),
+        PTP_RO_ATTR(max_adj,    max_adjustment),
+        PTP_RO_ATTR(n_alarm,    n_alarms),
+        PTP_RO_ATTR(n_ext_ts,   n_external_timestamps),
+        PTP_RO_ATTR(n_per_out,  n_periodic_outputs),
+        PTP_RO_ATTR(pps,        pps_available),
+        __ATTR_NULL,
+};
+
+static ssize_t extts_enable_store(struct device *dev,
+                                  struct device_attribute *attr,
+                                  const char *buf, size_t count)
+{
+        struct ptp_clock *ptp = dev_get_drvdata(dev);
+        struct ptp_clock_info *ops = ptp->info;
+        struct ptp_clock_request req = { .type = PTP_CLK_REQ_EXTTS };
+        int cnt, enable;
+        int err = -EINVAL;
+
+        cnt = sscanf(buf, "%u %d", &req.extts.index, &enable);
+        if (cnt != 2)
+                goto out;
+        if (req.extts.index >= ops->n_ext_ts)
+                goto out;
+
+        err = ops->enable(ops, &req, enable ? 1 : 0);
+        if (err)
+                goto out;
+
+        return count;
+out:
+        return err;
+}
+
+static ssize_t extts_fifo_show(struct device *dev,
+                               struct device_attribute *attr, char *page)
+{
+        struct ptp_clock *ptp = dev_get_drvdata(dev);
+        struct timestamp_event_queue *queue = &ptp->tsevq;
+        struct ptp_extts_event event;
+        unsigned long flags;
+        size_t qcnt;
+        int cnt = 0;
+
+        memset(&event, 0, sizeof(event));
+
+        if (mutex_lock_interruptible(&ptp->tsevq_mux))
+                return -ERESTARTSYS;
+
+        spin_lock_irqsave(&queue->lock, flags);
+        qcnt = queue_cnt(queue);
+        if (qcnt) {
+                event = queue->buf[queue->head];
+                queue->head = (queue->head + 1) % PTP_MAX_TIMESTAMPS;
+        }
+        spin_unlock_irqrestore(&queue->lock, flags);
+
+        if (!qcnt)
+                goto out;
+
+        cnt = snprintf(page, PAGE_SIZE, "%u %lld %u\n",
+                       event.index, event.t.sec, event.t.nsec);
+out:
+        mutex_unlock(&ptp->tsevq_mux);
+        return cnt;
+}
+
+static ssize_t period_store(struct device *dev,
+                            struct device_attribute *attr,
+                            const char *buf, size_t count)
+{
+        struct ptp_clock *ptp = dev_get_drvdata(dev);
+        struct ptp_clock_info *ops = ptp->info;
+        struct ptp_clock_request req = { .type = PTP_CLK_REQ_PEROUT };
+        int cnt, enable, err = -EINVAL;
+
+        cnt = sscanf(buf, "%u %lld %u %lld %u", &req.perout.index,
+                     &req.perout.start.sec, &req.perout.start.nsec,
+                     &req.perout.period.sec, &req.perout.period.nsec);
+        if (cnt != 5)
+                goto out;
+        if (req.perout.index >= ops->n_per_out)
+                goto out;
+
+        enable = req.perout.period.sec || req.perout.period.nsec;
+        err = ops->enable(ops, &req, enable);
+        if (err)
+                goto out;
+
+        return count;
+out:
+        return err;
+}
+
+static ssize_t pps_enable_store(struct device *dev,
+                                struct device_attribute *attr,
+                                const char *buf, size_t count)
+{
+        struct ptp_clock *ptp = dev_get_drvdata(dev);
+        struct ptp_clock_info *ops = ptp->info;
+        struct ptp_clock_request req = { .type = PTP_CLK_REQ_PPS };
+        int cnt, enable;
+        int err = -EINVAL;
+
+        if (!capable(CAP_SYS_TIME))
+                return -EPERM;
+
+        cnt = sscanf(buf, "%d", &enable);
+        if (cnt != 1)
+                goto out;
+
+        err = ops->enable(ops, &req, enable ? 1 : 0);
+        if (err)
+                goto out;
+
+        return count;
+out:
+        return err;
+}
+
+static DEVICE_ATTR(extts_enable, 0220, NULL, extts_enable_store);
+static DEVICE_ATTR(fifo,         0444, extts_fifo_show, NULL);
+static DEVICE_ATTR(period,       0220, NULL, period_store);
+static DEVICE_ATTR(pps_enable,   0220, NULL, pps_enable_store);
+
+int ptp_cleanup_sysfs(struct ptp_clock *ptp)
+{
+        struct device *dev = ptp->dev;
+        struct ptp_clock_info *info = ptp->info;
+
+        if (info->n_ext_ts) {
+                device_remove_file(dev, &dev_attr_extts_enable);
+                device_remove_file(dev, &dev_attr_fifo);
+        }
+        if (info->n_per_out)
+                device_remove_file(dev, &dev_attr_period);
+
+        if (info->pps)
+                device_remove_file(dev, &dev_attr_pps_enable);
+
+        return 0;
+}
+
+int ptp_populate_sysfs(struct ptp_clock *ptp)
+{
+        struct device *dev = ptp->dev;
+        struct ptp_clock_info *info = ptp->info;
+        int err;
+
+        if (info->n_ext_ts) {
+                err = device_create_file(dev, &dev_attr_extts_enable);
+                if (err)
+                        goto out1;
+                err = device_create_file(dev, &dev_attr_fifo);
+                if (err)
+                        goto out2;
+        }
+        if (info->n_per_out) {
+                err = device_create_file(dev, &dev_attr_period);
+                if (err)
+                        goto out3;
+        }
+        if (info->pps) {
+                err = device_create_file(dev, &dev_attr_pps_enable);
+                if (err)
+                        goto out4;
+        }
+        return 0;
+out4:
+        if (info->n_per_out)
+                device_remove_file(dev, &dev_attr_period);
+out3:
+        if (info->n_ext_ts)
+                device_remove_file(dev, &dev_attr_fifo);
+out2:
+        if (info->n_ext_ts)
+                device_remove_file(dev, &dev_attr_extts_enable);
+out1:
+        return err;
+}