soc: fsl: dpio: add support for irq coalescing per software portal

In DPAA2 based SoCs, the IRQ coalesing support per software portal has 2
configurable parameters:
 - the IRQ timeout period (QBMAN_CINH_SWP_ITPR): how many 256 QBMAN
   cycles need to pass until a dequeue interrupt is asserted.
 - the IRQ threshold (QBMAN_CINH_SWP_DQRR_ITR): how many dequeue
   responses in the DQRR ring would generate an IRQ.

Add support for setting up and querying these IRQ coalescing related
parameters.
Signed-off-by: Ioana Ciornei <ioana.ciornei@nxp.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/soc/fsl/dpio/dpio-service.c

@@ -114,6 +114,7 @@ struct dpaa2_io *dpaa2_io_create(const struct dpaa2_io_desc *desc,
 				 struct device *dev)
 {
 	struct dpaa2_io *obj = kmalloc(sizeof(*obj), GFP_KERNEL);
+	u32 qman_256_cycles_per_ns;
 
 	if (!obj)
 		return NULL;
@@ -129,6 +130,13 @@ struct dpaa2_io *dpaa2_io_create(const struct dpaa2_io_desc *desc,
 	obj->swp_desc.cinh_bar = obj->dpio_desc.regs_cinh;
 	obj->swp_desc.qman_clk = obj->dpio_desc.qman_clk;
 	obj->swp_desc.qman_version = obj->dpio_desc.qman_version;
+
+	/* Compute how many 256 QBMAN cycles fit into one ns. This is because
+	 * the interrupt timeout period register needs to be specified in QBMAN
+	 * clock cycles in increments of 256.
+	 */
+	qman_256_cycles_per_ns = 256000 / (obj->swp_desc.qman_clk / 1000000);
+	obj->swp_desc.qman_256_cycles_per_ns = qman_256_cycles_per_ns;
 	obj->swp = qbman_swp_init(&obj->swp_desc);
 
 	if (!obj->swp) {
@@ -780,3 +788,32 @@ int dpaa2_io_query_bp_count(struct dpaa2_io *d, u16 bpid, u32 *num)
 	return 0;
 }
 EXPORT_SYMBOL_GPL(dpaa2_io_query_bp_count);
+
+/**
+ * dpaa2_io_set_irq_coalescing() - Set new IRQ coalescing values
+ * @d: the given DPIO object
+ * @irq_holdoff: interrupt holdoff (timeout) period in us
+ *
+ * Return 0 for success, or negative error code on error.
+ */
+int dpaa2_io_set_irq_coalescing(struct dpaa2_io *d, u32 irq_holdoff)
+{
+	struct qbman_swp *swp = d->swp;
+
+	return qbman_swp_set_irq_coalescing(swp, swp->dqrr.dqrr_size - 1,
+					    irq_holdoff);
+}
+EXPORT_SYMBOL(dpaa2_io_set_irq_coalescing);
+
+/**
+ * dpaa2_io_get_irq_coalescing() - Get the current IRQ coalescing parameters
+ * @d: the given DPIO object
+ * @irq_holdoff: interrupt holdoff (timeout) period in us
+ */
+void dpaa2_io_get_irq_coalescing(struct dpaa2_io *d, u32 *irq_holdoff)
+{
+	struct qbman_swp *swp = d->swp;
+
+	qbman_swp_get_irq_coalescing(swp, NULL, irq_holdoff);
+}
+EXPORT_SYMBOL(dpaa2_io_get_irq_coalescing);

drivers/soc/fsl/dpio/qbman-portal.c

@@ -29,6 +29,7 @@
 #define QBMAN_CINH_SWP_EQCR_AM_RT   0x980
 #define QBMAN_CINH_SWP_RCR_AM_RT    0x9c0
 #define QBMAN_CINH_SWP_DQPI    0xa00
+#define QBMAN_CINH_SWP_DQRR_ITR     0xa80
 #define QBMAN_CINH_SWP_DCAP    0xac0
 #define QBMAN_CINH_SWP_SDQCR   0xb00
 #define QBMAN_CINH_SWP_EQCR_AM_RT2  0xb40
@@ -38,6 +39,7 @@
 #define QBMAN_CINH_SWP_IER     0xe40
 #define QBMAN_CINH_SWP_ISDR    0xe80
 #define QBMAN_CINH_SWP_IIR     0xec0
+#define QBMAN_CINH_SWP_ITPR    0xf40
 
 /* CENA register offsets */
 #define QBMAN_CENA_SWP_EQCR(n) (0x000 + ((u32)(n) << 6))
@@ -355,6 +357,9 @@ struct qbman_swp *qbman_swp_init(const struct qbman_swp_desc *d)
 			& p->eqcr.pi_ci_mask;
 	p->eqcr.available = p->eqcr.pi_ring_size;
 
+	/* Initialize the software portal with a irq timeout period of 0us */
+	qbman_swp_set_irq_coalescing(p, p->dqrr.dqrr_size - 1, 0);
+
 	return p;
 }
 
@@ -1796,3 +1801,57 @@ u32 qbman_bp_info_num_free_bufs(struct qbman_bp_query_rslt *a)
 {
 	return le32_to_cpu(a->fill);
 }
+
+/**
+ * qbman_swp_set_irq_coalescing() - Set new IRQ coalescing values
+ * @p: the software portal object
+ * @irq_threshold: interrupt threshold
+ * @irq_holdoff: interrupt holdoff (timeout) period in us
+ *
+ * Return 0 for success, or negative error code on error.
+ */
+int qbman_swp_set_irq_coalescing(struct qbman_swp *p, u32 irq_threshold,
+				 u32 irq_holdoff)
+{
+	u32 itp, max_holdoff;
+
+	/* Convert irq_holdoff value from usecs to 256 QBMAN clock cycles
+	 * increments. This depends to the QBMAN internal frequency.
+	 */
+	itp = (irq_holdoff * 1000) / p->desc->qman_256_cycles_per_ns;
+	if (itp < 0 || itp > 4096) {
+		max_holdoff = (p->desc->qman_256_cycles_per_ns * 4096) / 1000;
+		pr_err("irq_holdoff must be between 0..%dus\n", max_holdoff);
+		return -EINVAL;
+	}
+
+	if (irq_threshold >= p->dqrr.dqrr_size || irq_threshold < 0) {
+		pr_err("irq_threshold must be between 0..%d\n",
+		       p->dqrr.dqrr_size - 1);
+		return -EINVAL;
+	}
+
+	p->irq_threshold = irq_threshold;
+	p->irq_holdoff = irq_holdoff;
+
+	qbman_write_register(p, QBMAN_CINH_SWP_DQRR_ITR, irq_threshold);
+	qbman_write_register(p, QBMAN_CINH_SWP_ITPR, itp);
+
+	return 0;
+}
+
+/**
+ * qbman_swp_get_irq_coalescing() - Get the current IRQ coalescing parameters
+ * @p: the software portal object
+ * @irq_threshold: interrupt threshold (an IRQ is generated when there are more
+ * DQRR entries in the portal than the threshold)
+ * @irq_holdoff: interrupt holdoff (timeout) period in us
+ */
+void qbman_swp_get_irq_coalescing(struct qbman_swp *p, u32 *irq_threshold,
+				  u32 *irq_holdoff)
+{
+	if (irq_threshold)
+		*irq_threshold = p->irq_threshold;
+	if (irq_holdoff)
+		*irq_holdoff = p->irq_holdoff;
+}

drivers/soc/fsl/dpio/qbman-portal.h

@@ -25,6 +25,7 @@ struct qbman_swp_desc {
 	void __iomem *cinh_bar; /* Cache-inhibited portal base address */
 	u32 qman_version;
 	u32 qman_clk;
+	u32 qman_256_cycles_per_ns;
 };
 
 #define QBMAN_SWP_INTERRUPT_EQRI 0x01
@@ -157,6 +158,10 @@ struct qbman_swp {
 	} eqcr;
 
 	spinlock_t access_spinlock;
+
+	/* Interrupt coalescing */
+	u32 irq_threshold;
+	u32 irq_holdoff;
 };
 
 /* Function pointers */
@@ -649,4 +654,10 @@ static inline const struct dpaa2_dq *qbman_swp_dqrr_next(struct qbman_swp *s)
 	return qbman_swp_dqrr_next_ptr(s);
 }
 
+int qbman_swp_set_irq_coalescing(struct qbman_swp *p, u32 irq_threshold,
+				 u32 irq_holdoff);
+
+void qbman_swp_get_irq_coalescing(struct qbman_swp *p, u32 *irq_threshold,
+				  u32 *irq_holdoff);
+
 #endif /* __FSL_QBMAN_PORTAL_H */

include/soc/fsl/dpaa2-io.h

@@ -131,4 +131,8 @@ int dpaa2_io_query_fq_count(struct dpaa2_io *d, u32 fqid,
 			    u32 *fcnt, u32 *bcnt);
 int dpaa2_io_query_bp_count(struct dpaa2_io *d, u16 bpid,
 			    u32 *num);
+
+int dpaa2_io_set_irq_coalescing(struct dpaa2_io *d, u32 irq_holdoff);
+void dpaa2_io_get_irq_coalescing(struct dpaa2_io *d, u32 *irq_holdoff);
+
 #endif /* __FSL_DPAA2_IO_H */