ptp: introduce programmable pins.

This patch adds a pair of new ioctls to the PTP Hardware Clock device
interface. Using the ioctls, user space programs can query each pin to
find out its current function and also reprogram a different function
if desired.

Signed-off-by: Richard Cochran <richardcochran@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

5 files changed, 226 insertions, 2 deletions

diff --git a/drivers/ptp/ptp_chardev.c b/drivers/ptp/ptp_chardev.c
index 34a0c607318e..419056d7887e 100644
--- a/drivers/ptp/ptp_chardev.c
+++ b/drivers/ptp/ptp_chardev.c
@@ -25,6 +25,96 @@
 
 #include "ptp_private.h"
 
+static int ptp_disable_pinfunc(struct ptp_clock_info *ops,
+                               enum ptp_pin_function func, unsigned int chan)
+{
+        struct ptp_clock_request rq;
+        int err = 0;
+
+        memset(&rq, 0, sizeof(rq));
+
+        switch (func) {
+        case PTP_PF_NONE:
+                break;
+        case PTP_PF_EXTTS:
+                rq.type = PTP_CLK_REQ_EXTTS;
+                rq.extts.index = chan;
+                err = ops->enable(ops, &rq, 0);
+                break;
+        case PTP_PF_PEROUT:
+                rq.type = PTP_CLK_REQ_PEROUT;
+                rq.perout.index = chan;
+                err = ops->enable(ops, &rq, 0);
+                break;
+        case PTP_PF_PHYSYNC:
+                break;
+        default:
+                return -EINVAL;
+        }
+
+        return err;
+}
+
+int ptp_set_pinfunc(struct ptp_clock *ptp, unsigned int pin,
+                    enum ptp_pin_function func, unsigned int chan)
+{
+        struct ptp_clock_info *info = ptp->info;
+        struct ptp_pin_desc *pin1 = NULL, *pin2 = &info->pin_config[pin];
+        unsigned int i;
+
+        /* Check to see if any other pin previously had this function. */
+        for (i = 0; i < info->n_pins; i++) {
+                if (info->pin_config[i].func == func &&
+                    info->pin_config[i].chan == chan) {
+                        pin1 = &info->pin_config[i];
+                        break;
+                }
+        }
+        if (pin1 && i == pin)
+                return 0;
+
+        /* Check the desired function and channel. */
+        switch (func) {
+        case PTP_PF_NONE:
+                break;
+        case PTP_PF_EXTTS:
+                if (chan >= info->n_ext_ts)
+                        return -EINVAL;
+                break;
+        case PTP_PF_PEROUT:
+                if (chan >= info->n_per_out)
+                        return -EINVAL;
+                break;
+        case PTP_PF_PHYSYNC:
+                pr_err("sorry, cannot reassign the calibration pin\n");
+                return -EINVAL;
+        default:
+                return -EINVAL;
+        }
+
+        if (pin2->func == PTP_PF_PHYSYNC) {
+                pr_err("sorry, cannot reprogram the calibration pin\n");
+                return -EINVAL;
+        }
+
+        if (info->verify(info, pin, func, chan)) {
+                pr_err("driver cannot use function %u on pin %u\n", func, chan);
+                return -EOPNOTSUPP;
+        }
+
+        /* Disable whatever function was previously assigned. */
+        if (pin1) {
+                ptp_disable_pinfunc(info, func, chan);
+                pin1->func = PTP_PF_NONE;
+                pin1->chan = 0;
+        }
+        ptp_disable_pinfunc(info, pin2->func, pin2->chan);
+        pin2->func = func;
+        pin2->chan = chan;
+
+        return 0;
+}
+
 int ptp_open(struct posix_clock *pc, fmode_t fmode)
 {
         return 0;
@@ -35,12 +125,13 @@ 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_sys_offset *sysoff = NULL;
+        struct ptp_pin_desc pd;
         struct ptp_clock *ptp = container_of(pc, struct ptp_clock, clock);
         struct ptp_clock_info *ops = ptp->info;
         struct ptp_clock_time *pct;
         struct timespec ts;
         int enable, err = 0;
-        unsigned int i;
+        unsigned int i, pin_index;
 
         switch (cmd) {
 
@@ -51,6 +142,7 @@ long ptp_ioctl(struct posix_clock *pc, unsigned int cmd, unsigned long arg)
                 caps.n_ext_ts = ptp->info->n_ext_ts;
                 caps.n_per_out = ptp->info->n_per_out;
                 caps.pps = ptp->info->pps;
+                caps.n_pins = ptp->info->n_pins;
                 if (copy_to_user((void __user *)arg, &caps, sizeof(caps)))
                         err = -EFAULT;
                 break;
@@ -126,6 +218,40 @@ long ptp_ioctl(struct posix_clock *pc, unsigned int cmd, unsigned long arg)
                         err = -EFAULT;
                 break;
 
+        case PTP_PIN_GETFUNC:
+                if (copy_from_user(&pd, (void __user *)arg, sizeof(pd))) {
+                        err = -EFAULT;
+                        break;
+                }
+                pin_index = pd.index;
+                if (pin_index >= ops->n_pins) {
+                        err = -EINVAL;
+                        break;
+                }
+                if (mutex_lock_interruptible(&ptp->pincfg_mux))
+                        return -ERESTARTSYS;
+                pd = ops->pin_config[pin_index];
+                mutex_unlock(&ptp->pincfg_mux);
+                if (!err && copy_to_user((void __user *)arg, &pd, sizeof(pd)))
+                        err = -EFAULT;
+                break;
+
+        case PTP_PIN_SETFUNC:
+                if (copy_from_user(&pd, (void __user *)arg, sizeof(pd))) {
+                        err = -EFAULT;
+                        break;
+                }
+                pin_index = pd.index;
+                if (pin_index >= ops->n_pins) {
+                        err = -EINVAL;
+                        break;
+                }
+                if (mutex_lock_interruptible(&ptp->pincfg_mux))
+                        return -ERESTARTSYS;
+                err = ptp_set_pinfunc(ptp, pin_index, pd.func, pd.chan);
+                mutex_unlock(&ptp->pincfg_mux);
+                break;
+
         default:
                 err = -ENOTTY;
                 break;
diff --git a/drivers/ptp/ptp_clock.c b/drivers/ptp/ptp_clock.c
index a8319b266643..e25d2bc898e5 100644
--- a/drivers/ptp/ptp_clock.c
+++ b/drivers/ptp/ptp_clock.c
@@ -169,6 +169,7 @@ static void delete_ptp_clock(struct posix_clock *pc)
         struct ptp_clock *ptp = container_of(pc, struct ptp_clock, clock);
 
         mutex_destroy(&ptp->tsevq_mux);
+        mutex_destroy(&ptp->pincfg_mux);
         ida_simple_remove(&ptp_clocks_map, ptp->index);
         kfree(ptp);
 }
@@ -203,6 +204,7 @@ struct ptp_clock *ptp_clock_register(struct ptp_clock_info *info,
         ptp->index = index;
         spin_lock_init(&ptp->tsevq.lock);
         mutex_init(&ptp->tsevq_mux);
+        mutex_init(&ptp->pincfg_mux);
         init_waitqueue_head(&ptp->tsev_wq);
 
         /* Create a new device in our class. */
@@ -249,6 +251,7 @@ no_sysfs:
         device_destroy(ptp_class, ptp->devid);
 no_device:
         mutex_destroy(&ptp->tsevq_mux);
+        mutex_destroy(&ptp->pincfg_mux);
 no_slot:
         kfree(ptp);
 no_memory:
@@ -305,6 +308,26 @@ int ptp_clock_index(struct ptp_clock *ptp)
 }
 EXPORT_SYMBOL(ptp_clock_index);
 
+int ptp_find_pin(struct ptp_clock *ptp,
+                 enum ptp_pin_function func, unsigned int chan)
+{
+        struct ptp_pin_desc *pin = NULL;
+        int i;
+
+        mutex_lock(&ptp->pincfg_mux);
+        for (i = 0; i < ptp->info->n_pins; i++) {
+                if (ptp->info->pin_config[i].func == func &&
+                    ptp->info->pin_config[i].chan == chan) {
+                        pin = &ptp->info->pin_config[i];
+                        break;
+                }
+        }
+        mutex_unlock(&ptp->pincfg_mux);
+
+        return pin ? i : -1;
+}
+EXPORT_SYMBOL(ptp_find_pin);
+
 /* module operations */
 
 static void __exit ptp_exit(void)
diff --git a/drivers/ptp/ptp_private.h b/drivers/ptp/ptp_private.h
index df03f2e30ad9..b114a84c63c7 100644
--- a/drivers/ptp/ptp_private.h
+++ b/drivers/ptp/ptp_private.h
@@ -48,6 +48,7 @@ struct ptp_clock {
         long dialed_frequency; /* remembers the frequency adjustment */
         struct timestamp_event_queue tsevq; /* simple fifo for time stamps */
         struct mutex tsevq_mux; /* one process at a time reading the fifo */
+        struct mutex pincfg_mux; /* protect concurrent info->pin_config access */
         wait_queue_head_t tsev_wq;
         int defunct; /* tells readers to go away when clock is being removed */
 };
@@ -69,6 +70,10 @@ static inline int queue_cnt(struct timestamp_event_queue *q)
  * see ptp_chardev.c
  */
 
+/* caller must hold pincfg_mux */
+int ptp_set_pinfunc(struct ptp_clock *ptp, unsigned int pin,
+                    enum ptp_pin_function func, unsigned int chan);
+
 long ptp_ioctl(struct posix_clock *pc,
                unsigned int cmd, unsigned long arg);
 
diff --git a/include/linux/ptp_clock_kernel.h b/include/linux/ptp_clock_kernel.h
index 38a993508327..0d8ff3fb84ba 100644
--- a/include/linux/ptp_clock_kernel.h
+++ b/include/linux/ptp_clock_kernel.h
@@ -49,7 +49,11 @@ struct ptp_clock_request {
  * @n_alarm:   The number of programmable alarms.
  * @n_ext_ts:  The number of external time stamp channels.
  * @n_per_out: The number of programmable periodic signals.
+ * @n_pins:    The number of programmable pins.
  * @pps:       Indicates whether the clock supports a PPS callback.
+ * @pin_config: Array of length 'n_pins'. If the number of
+ *              programmable pins is nonzero, then drivers must
+ *              allocate and initialize this array.
  *
  * clock operations
  *
@@ -70,6 +74,18 @@ struct ptp_clock_request {
  *            parameter request: Desired resource to enable or disable.
  *            parameter on: Caller passes one to enable or zero to disable.
  *
+ * @verify:   Confirm that a pin can perform a given function. The PTP
+ *            Hardware Clock subsystem maintains the 'pin_config'
+ *            array on behalf of the drivers, but the PHC subsystem
+ *            assumes that every pin can perform every function. This
+ *            hook gives drivers a way of telling the core about
+ *            limitations on specific pins. This function must return
+ *            zero if the function can be assigned to this pin, and
+ *            nonzero otherwise.
+ *            parameter pin: index of the pin in question.
+ *            parameter func: the desired function to use.
+ *            parameter chan: the function channel index to use.
+ *
  * Drivers should embed their ptp_clock_info within a private
  * structure, obtaining a reference to it using container_of().
  *
@@ -83,13 +99,17 @@ struct ptp_clock_info {
         int n_alarm;
         int n_ext_ts;
         int n_per_out;
+        int n_pins;
         int pps;
+        struct ptp_pin_desc *pin_config;
         int (*adjfreq)(struct ptp_clock_info *ptp, s32 delta);
         int (*adjtime)(struct ptp_clock_info *ptp, s64 delta);
         int (*gettime)(struct ptp_clock_info *ptp, struct timespec *ts);
         int (*settime)(struct ptp_clock_info *ptp, const struct timespec *ts);
         int (*enable)(struct ptp_clock_info *ptp,
                       struct ptp_clock_request *request, int on);
+        int (*verify)(struct ptp_clock_info *ptp, unsigned int pin,
+                      enum ptp_pin_function func, unsigned int chan);
 };
 
 struct ptp_clock;
@@ -156,4 +176,17 @@ extern void ptp_clock_event(struct ptp_clock *ptp,
 
 extern int ptp_clock_index(struct ptp_clock *ptp);
 
+/**
+ * ptp_find_pin() - obtain the pin index of a given auxiliary function
+ *
+ * @ptp:    The clock obtained from ptp_clock_register().
+ * @func:   One of the ptp_pin_function enumerated values.
+ * @chan:   The particular functional channel to find.
+ * Return:  Pin index in the range of zero to ptp_clock_caps.n_pins - 1,
+ *          or -1 if the auxiliary function cannot be found.
+ */
+
+int ptp_find_pin(struct ptp_clock *ptp,
+                 enum ptp_pin_function func, unsigned int chan);
+
 #endif
diff --git a/include/uapi/linux/ptp_clock.h b/include/uapi/linux/ptp_clock.h
index b65c834f83e9..f0b7bfe5da92 100644
--- a/include/uapi/linux/ptp_clock.h
+++ b/include/uapi/linux/ptp_clock.h
@@ -50,7 +50,8 @@ struct ptp_clock_caps {
         int n_ext_ts;  /* Number of external time stamp channels. */
         int n_per_out; /* Number of programmable periodic signals. */
         int pps;       /* Whether the clock supports a PPS callback. */
-        int rsv[15];   /* Reserved for future use. */
+        int n_pins;    /* Number of input/output pins. */
+        int rsv[14];   /* Reserved for future use. */
 };
 
 struct ptp_extts_request {
@@ -80,6 +81,40 @@ struct ptp_sys_offset {
         struct ptp_clock_time ts[2 * PTP_MAX_SAMPLES + 1];
 };
 
+enum ptp_pin_function {
+        PTP_PF_NONE,
+        PTP_PF_EXTTS,
+        PTP_PF_PEROUT,
+        PTP_PF_PHYSYNC,
+};
+
+struct ptp_pin_desc {
+        /*
+         * Hardware specific human readable pin name. This field is
+         * set by the kernel during the PTP_PIN_GETFUNC ioctl and is
+         * ignored for the PTP_PIN_SETFUNC ioctl.
+         */
+        char name[64];
+        /*
+         * Pin index in the range of zero to ptp_clock_caps.n_pins - 1.
+         */
+        unsigned int index;
+        /*
+         * Which of the PTP_PF_xxx functions to use on this pin.
+         */
+        unsigned int func;
+        /*
+         * The specific channel to use for this function.
+         * This corresponds to the 'index' field of the
+         * PTP_EXTTS_REQUEST and PTP_PEROUT_REQUEST ioctls.
+         */
+        unsigned int chan;
+        /*
+         * Reserved for future use.
+         */
+        unsigned int rsv[5];
+};
+
 #define PTP_CLK_MAGIC '='
 
 #define PTP_CLOCK_GETCAPS  _IOR(PTP_CLK_MAGIC, 1, struct ptp_clock_caps)
@@ -87,6 +122,8 @@ struct ptp_sys_offset {
 #define PTP_PEROUT_REQUEST _IOW(PTP_CLK_MAGIC, 3, struct ptp_perout_request)
 #define PTP_ENABLE_PPS     _IOW(PTP_CLK_MAGIC, 4, int)
 #define PTP_SYS_OFFSET     _IOW(PTP_CLK_MAGIC, 5, struct ptp_sys_offset)
+#define PTP_PIN_GETFUNC    _IOWR(PTP_CLK_MAGIC, 6, struct ptp_pin_desc)
+#define PTP_PIN_SETFUNC    _IOW(PTP_CLK_MAGIC, 7, struct ptp_pin_desc)
 
 struct ptp_extts_event {
         struct ptp_clock_time t; /* Time event occured. */