[PATCH 9/9] irqchip/ls-scfg-msi: add MSI affinity support

[Minghuan Lian]

For LS1046a and LS1043a v1.1, the MSI controller has 4 MSIRs and 4
CPUs. A GIC SPI interrupt of MSIR can be associated with a CPU.
When changing MSI interrupt affinity, this MSI will be moved to the
corresponding MSIR and MSI message data will be changed according to
MSIR. when requesting a MSI, the bits of all 4 MSIR will be reserved.
The parameter 'msi_affinity_flag' is provide to change this mode.
"lsmsi=no-affinity" will disable affinity, all MSI can only be
associated with CPU 0.

Signed-off-by: Minghuan Lian <Minghuan.Lian@xxxxxxx>
---
 drivers/irqchip/irq-ls-scfg-msi.c | 75 ++++++++++++++++++++++++++++++++++++---
 1 file changed, 70 insertions(+), 5 deletions(-)

diff --git a/drivers/irqchip/irq-ls-scfg-msi.c b/drivers/irqchip/irq-ls-scfg-msi.c
index dc19569..753fe39 100644
--- a/drivers/irqchip/irq-ls-scfg-msi.c
+++ b/drivers/irqchip/irq-ls-scfg-msi.c
@@ -40,6 +40,7 @@ struct ls_scfg_msir {
 	unsigned int gic_irq;
 	unsigned int bit_start;
 	unsigned int bit_end;
+	unsigned int srs; /* Shared interrupt register select */
 	void __iomem *reg;
 };
 
@@ -70,6 +71,19 @@ struct ls_scfg_msi {
 	.chip	= &ls_scfg_msi_irq_chip,
 };
 
+static int msi_affinity_flag = 1;
+
+static int __init early_parse_ls_scfg_msi(char *p)
+{
+	if (p && strncmp(p, "no-affinity", 11) == 0)
+		msi_affinity_flag = 0;
+	else
+		msi_affinity_flag = 1;
+
+	return 0;
+}
+early_param("lsmsi", early_parse_ls_scfg_msi);
+
 static void ls_scfg_msi_compose_msg(struct irq_data *data, struct msi_msg *msg)
 {
 	struct ls_scfg_msi *msi_data = irq_data_get_irq_chip_data(data);
@@ -77,12 +91,43 @@ static void ls_scfg_msi_compose_msg(struct irq_data *data, struct msi_msg *msg)
 	msg->address_hi = upper_32_bits(msi_data->msiir_addr);
 	msg->address_lo = lower_32_bits(msi_data->msiir_addr);
 	msg->data = data->hwirq;
+
+	if (msi_affinity_flag) {
+		u32 msir_index;
+
+		msir_index = cpumask_first(data->common->affinity);
+		if (msir_index >= msi_data->msir_num)
+			msir_index = 0;
+
+		msg->data |= msir_index;
+	}
 }
 
 static int ls_scfg_msi_set_affinity(struct irq_data *irq_data,
 				    const struct cpumask *mask, bool force)
 {
-	return -EINVAL;
+	struct ls_scfg_msi *msi_data = irq_data_get_irq_chip_data(irq_data);
+	u32 cpu;
+
+	if (!msi_affinity_flag)
+		return -EINVAL;
+
+	if (!force)
+		cpu = cpumask_any_and(mask, cpu_online_mask);
+	else
+		cpu = cpumask_first(mask);
+
+	if (cpu >= msi_data->msir_num)
+		return -EINVAL;
+
+	if (msi_data->msir[cpu].gic_irq <= 0) {
+		pr_warn("cannot bind the irq to cpu%d\n", cpu);
+		return -EINVAL;
+	}
+
+	cpumask_copy(irq_data->common->affinity, mask);
+
+	return IRQ_SET_MASK_OK;
 }
 
 static struct irq_chip ls_scfg_msi_parent_chip = {
@@ -158,7 +203,7 @@ static void ls_scfg_msi_irq_handler(struct irq_desc *desc)
 
 	for_each_set_bit_from(pos, &val, size) {
 		hwirq = ((msir->bit_end - pos) << msi_data->cfg->ibs_shift) |
-			msir->index;
+			msir->srs;
 		virq = irq_find_mapping(msi_data->parent, hwirq);
 		if (virq)
 			generic_handle_irq(virq);
@@ -221,10 +266,19 @@ static int ls_scfg_msi_setup_hwirq(struct ls_scfg_msi *msi_data, int index)
 					 ls_scfg_msi_irq_handler,
 					 msir);
 
+	if (msi_affinity_flag) {
+		/* Associate MSIR interrupt to the cpu */
+		irq_set_affinity(msir->gic_irq, get_cpu_mask(index));
+		msir->srs = 0; /* This value is determined by the CPU */
+	} else
+		msir->srs = index;
+
 	/* Release the hwirqs corresponding to this MSIR */
-	for (i = 0; i < msi_data->cfg->msir_irqs; i++) {
-		hwirq = i << msi_data->cfg->ibs_shift | msir->index;
-		bitmap_clear(msi_data->used, hwirq, 1);
+	if (!msi_affinity_flag || msir->index == 0) {
+		for (i = 0; i < msi_data->cfg->msir_irqs; i++) {
+			hwirq = i << msi_data->cfg->ibs_shift | msir->index;
+			bitmap_clear(msi_data->used, hwirq, 1);
+		}
 	}
 
 	return 0;
@@ -316,6 +370,17 @@ static int ls_scfg_msi_probe(struct platform_device *pdev)
 	bitmap_set(msi_data->used, 0, msi_data->irqs_num);
 
 	msi_data->msir_num = of_irq_count(pdev->dev.of_node);
+
+	if (msi_affinity_flag) {
+		u32 cpu_num;
+
+		cpu_num = num_possible_cpus();
+		if (msi_data->msir_num >= cpu_num)
+			msi_data->msir_num = cpu_num;
+		else
+			msi_affinity_flag = 0;
+	}
+
 	msi_data->msir = devm_kcalloc(&pdev->dev, msi_data->msir_num,
 				      sizeof(*msi_data->msir),
 				      GFP_KERNEL);
-- 
1.9.1