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>

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;

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)

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);