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 <[e-mail]>
Signed-off-by: David S. Miller <[e-mail]>

drivers/ptp/ptp_chardev.c

···
 
 #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;
···
 	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) {
 
···
 		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;
···
 		pct->nsec = ts.tv_nsec;
 		if (copy_to_user((void __user *)arg, sysoff, sizeof(*sysoff)))
 			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:

drivers/ptp/ptp_clock.c

···
 	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);
 }
···
 	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. */
···
 	device_destroy(ptp_class, ptp->devid);
 no_device:
 	mutex_destroy(&ptp->tsevq_mux);
+	mutex_destroy(&ptp->pincfg_mux);
 no_slot:
 	kfree(ptp);
 no_memory:
···
 	return ptp->index;
 }
 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 */
 

drivers/ptp/ptp_private.h

···
 	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 */
 };
···
 /*
  * 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);

include/linux/ptp_clock_kernel.h

···
  * @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
  *
···
  *            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().
  *
···
 	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;
···
  */
 
 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

include/uapi/linux/ptp_clock.h

···
 	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 {
···
 	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)
···
 #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. */