net: ti: icss-iep: Enable compare events

The IEP module supports compare events, in which a value is written to a
hardware register and when the IEP counter reaches the written value an
interrupt is generated. Add handling for this interrupt in order to
support PPS events.
Reviewed-by: Wojciech Drewek <wojciech.drewek@intel.com>
Reviewed-by: Jacob Keller <jacob.e.keller@intel.com>
Signed-off-by: Diogo Ivo <diogo.ivo@siemens.com>
Reviewed-by: Simon Horman <horms@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/ti/icssg/icss_iep.c

@@ -17,6 +17,7 @@
 #include <linux/timekeeping.h>
 #include <linux/interrupt.h>
 #include <linux/of_irq.h>
+#include <linux/workqueue.h>
 
 #include "icss_iep.h"
 
@@ -121,6 +122,7 @@ struct icss_iep {
 	int cap_cmp_irq;
 	u64 period;
 	u32 latch_enable;
+	struct work_struct work;
 };
 
 /**
@@ -563,6 +565,57 @@ static int icss_iep_perout_enable(struct icss_iep *iep,
 	return ret;
 }
 
+static void icss_iep_cap_cmp_work(struct work_struct *work)
+{
+	struct icss_iep *iep = container_of(work, struct icss_iep, work);
+	const u32 *reg_offs = iep->plat_data->reg_offs;
+	struct ptp_clock_event pevent;
+	unsigned int val;
+	u64 ns, ns_next;
+
+	mutex_lock(&iep->ptp_clk_mutex);
+
+	ns = readl(iep->base + reg_offs[ICSS_IEP_CMP1_REG0]);
+	if (iep->plat_data->flags & ICSS_IEP_64BIT_COUNTER_SUPPORT) {
+		val = readl(iep->base + reg_offs[ICSS_IEP_CMP1_REG1]);
+		ns |= (u64)val << 32;
+	}
+	/* set next event */
+	ns_next = ns + iep->period;
+	writel(lower_32_bits(ns_next),
+	       iep->base + reg_offs[ICSS_IEP_CMP1_REG0]);
+	if (iep->plat_data->flags & ICSS_IEP_64BIT_COUNTER_SUPPORT)
+		writel(upper_32_bits(ns_next),
+		       iep->base + reg_offs[ICSS_IEP_CMP1_REG1]);
+
+	pevent.pps_times.ts_real = ns_to_timespec64(ns);
+	pevent.type = PTP_CLOCK_PPSUSR;
+	pevent.index = 0;
+	ptp_clock_event(iep->ptp_clock, &pevent);
+	dev_dbg(iep->dev, "IEP:pps ts: %llu next:%llu:\n", ns, ns_next);
+
+	mutex_unlock(&iep->ptp_clk_mutex);
+}
+
+static irqreturn_t icss_iep_cap_cmp_irq(int irq, void *dev_id)
+{
+	struct icss_iep *iep = (struct icss_iep *)dev_id;
+	const u32 *reg_offs = iep->plat_data->reg_offs;
+	unsigned int val;
+
+	val = readl(iep->base + reg_offs[ICSS_IEP_CMP_STAT_REG]);
+	/* The driver only enables CMP1 */
+	if (val & BIT(1)) {
+		/* Clear the event */
+		writel(BIT(1), iep->base + reg_offs[ICSS_IEP_CMP_STAT_REG]);
+		if (iep->pps_enabled || iep->perout_enabled)
+			schedule_work(&iep->work);
+		return IRQ_HANDLED;
+	}
+
+	return IRQ_NONE;
+}
+
 static int icss_iep_pps_enable(struct icss_iep *iep, int on)
 {
 	struct ptp_clock_request rq;
@@ -591,6 +644,8 @@ static int icss_iep_pps_enable(struct icss_iep *iep, int on)
 		ret = icss_iep_perout_enable_hw(iep, &rq.perout, on);
 	} else {
 		ret = icss_iep_perout_enable_hw(iep, &rq.perout, on);
+		if (iep->cap_cmp_irq)
+			cancel_work_sync(&iep->work);
 	}
 
 	if (!ret)
@@ -764,6 +819,8 @@ int icss_iep_init(struct icss_iep *iep, const struct icss_iep_clockops *clkops,
 	if (iep->ops && iep->ops->perout_enable) {
 		iep->ptp_info.n_per_out = 1;
 		iep->ptp_info.pps = 1;
+	} else if (iep->cap_cmp_irq) {
+		iep->ptp_info.pps = 1;
 	}
 
 	if (iep->ops && iep->ops->extts_enable)
@@ -804,6 +861,7 @@ static int icss_iep_probe(struct platform_device *pdev)
 	struct device *dev = &pdev->dev;
 	struct icss_iep *iep;
 	struct clk *iep_clk;
+	int ret, irq;
 
 	iep = devm_kzalloc(dev, sizeof(*iep), GFP_KERNEL);
 	if (!iep)
@@ -814,6 +872,22 @@ static int icss_iep_probe(struct platform_device *pdev)
 	if (IS_ERR(iep->base))
 		return -ENODEV;
 
+	irq = platform_get_irq_byname_optional(pdev, "iep_cap_cmp");
+	if (irq == -EPROBE_DEFER)
+		return irq;
+
+	if (irq > 0) {
+		ret = devm_request_irq(dev, irq, icss_iep_cap_cmp_irq,
+				       IRQF_TRIGGER_HIGH, "iep_cap_cmp", iep);
+		if (ret) {
+			dev_info(iep->dev, "cap_cmp irq request failed: %x\n",
+				 ret);
+		} else {
+			iep->cap_cmp_irq = irq;
+			INIT_WORK(&iep->work, icss_iep_cap_cmp_work);
+		}
+	}
+
 	iep_clk = devm_clk_get(dev, NULL);
 	if (IS_ERR(iep_clk))
 		return PTR_ERR(iep_clk);