Re: [PATCH 04/13] irqchip: Add driver for Loongson-3 I/O interrupt controller
From: Jiaxun Yang
Date: Tue Aug 27 2019 - 20:27:34 EST
On 2019/8/28 äå12:45, Marc Zyngier wrote:
On 27/08/2019 09:52, Jiaxun Yang wrote:
This controller appeared on Loongson-3 family of chips as the primary
package interrupt source.
Signed-off-by: Jiaxun Yang <jiaxun.yang@xxxxxxxxxxx>
---
drivers/irqchip/Kconfig | 9 ++
drivers/irqchip/Makefile | 1 +
drivers/irqchip/irq-ls3-iointc.c | 216 +++++++++++++++++++++++++++++++
3 files changed, 226 insertions(+)
create mode 100644 drivers/irqchip/irq-ls3-iointc.c
diff --git a/drivers/irqchip/Kconfig b/drivers/irqchip/Kconfig
index 80e10f4e213a..8d9eac5fd4a7 100644
--- a/drivers/irqchip/Kconfig
+++ b/drivers/irqchip/Kconfig
@@ -471,6 +471,15 @@ config TI_SCI_INTA_IRQCHIP
If you wish to use interrupt aggregator irq resources managed by the
TI System Controller, say Y here. Otherwise, say N.
+config LS3_IOINTC
+ bool "Loongson3 I/O Interrupt Controller"
+ depends on MACH_LOONGSON64
+ default y
+ select IRQ_DOMAIN
+ select GENERIC_IRQ_CHIP
+ help
+ Support for the Loongson-3 I/O Interrupt Controller.
+
endmenu
config SIFIVE_PLIC
diff --git a/drivers/irqchip/Makefile b/drivers/irqchip/Makefile
index 8d0fcec6ab23..49ecb8d38138 100644
--- a/drivers/irqchip/Makefile
+++ b/drivers/irqchip/Makefile
@@ -102,3 +102,4 @@ obj-$(CONFIG_MADERA_IRQ) += irq-madera.o
obj-$(CONFIG_LS1X_IRQ) += irq-ls1x.o
obj-$(CONFIG_TI_SCI_INTR_IRQCHIP) += irq-ti-sci-intr.o
obj-$(CONFIG_TI_SCI_INTA_IRQCHIP) += irq-ti-sci-inta.o
+obj-$(CONFIG_LS3_IOINTC) += irq-ls3-iointc.o
diff --git a/drivers/irqchip/irq-ls3-iointc.c b/drivers/irqchip/irq-ls3-iointc.c
new file mode 100644
index 000000000000..1fc3c41c57d9
--- /dev/null
+++ b/drivers/irqchip/irq-ls3-iointc.c
@@ -0,0 +1,216 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2019, Jiaxun Yang <jiaxun.yang@xxxxxxxxxxx>
+ * Loongson-3 IOINTC IRQ support
+ */
+
+#include <linux/errno.h>
+#include <linux/init.h>
+#include <linux/types.h>
+#include <linux/interrupt.h>
+#include <linux/ioport.h>
+#include <linux/irqchip.h>
+#include <linux/of_address.h>
+#include <linux/of_irq.h>
+#include <linux/io.h>
+#include <linux/smp.h>
+#include <linux/irqchip/chained_irq.h>
+
+
+#define LS3_CHIP_IRQ 32
+
+#define LS3_INTC_CHIP_START 0x20
+
+#define LS3_REG_INTC_STATUS 0x00
+#define LS3_REG_INTC_EN_STATUS 0x04
+#define LS3_REG_INTC_ENABLE 0x08
+#define LS3_REG_INTC_DISABLE 0x0c
+#define LS3_REG_INTC_POL 0x10
+#define LS3_REG_INTC_EDGE 0x18
+
+#define LS3_MAP_CORE_INT(x, y) (u8)(BIT(x) | (BIT(y) << 4))
+
+
+struct ls3_iointc_priv {
+ struct irq_domain *domain;
+ void __iomem *intc_base;
+};
+
+
+static void ls3_io_chained_handle_irq(struct irq_desc *desc)
+{
+ struct ls3_iointc_priv *priv = irq_desc_get_handler_data(desc);
+ struct irq_chip *chip = irq_desc_get_chip(desc);
+ u32 pending;
+
+ chained_irq_enter(chip, desc);
+
+ pending = readl(priv->intc_base + LS3_REG_INTC_EN_STATUS) &
+ readl(priv->intc_base + LS3_REG_INTC_STATUS);
Reading the enabled status from the HW on each interrupt? I'm sure
that's pretty cheap...
Seems expensive but to deal with a buggy hardware... That's worthy.
+
+ if (!pending)
+ spurious_interrupt();
+
+ while (pending) {
+ int bit = __ffs(pending);
+
+ generic_handle_irq(irq_find_mapping(priv->domain, bit));
+ pending &= ~BIT(bit);
+ }
+
+ chained_irq_exit(chip, desc);
+}
+
+
+static void ls_intc_set_bit(struct irq_chip_generic *gc,
+ unsigned int offset,
+ u32 mask, bool set)
+{
+ if (set)
+ writel(readl(gc->reg_base + offset) | mask,
+ gc->reg_base + offset);
Please correctly align the second line.
+ else
+ writel(readl(gc->reg_base + offset) & ~mask,
+ gc->reg_base + offset);
+}
Have you tried this on a SMP system? A RMW without locking is unlikely
to go down very well.
+
+static int ls_intc_set_type(struct irq_data *data, unsigned int type)
+{
+ struct irq_chip_generic *gc = irq_data_get_irq_chip_data(data);
+ u32 mask = data->mask;
+
+ switch (type) {
+ case IRQ_TYPE_LEVEL_HIGH:
+ ls_intc_set_bit(gc, LS3_REG_INTC_EDGE, mask, false);
+ ls_intc_set_bit(gc, LS3_REG_INTC_POL, mask, true);
+ break;
+ case IRQ_TYPE_LEVEL_LOW:
+ ls_intc_set_bit(gc, LS3_REG_INTC_EDGE, mask, false);
+ ls_intc_set_bit(gc, LS3_REG_INTC_POL, mask, false);
+ break;
+ case IRQ_TYPE_EDGE_RISING:
+ ls_intc_set_bit(gc, LS3_REG_INTC_EDGE, mask, true);
+ ls_intc_set_bit(gc, LS3_REG_INTC_POL, mask, true);
+ break;
+ case IRQ_TYPE_EDGE_FALLING:
+ ls_intc_set_bit(gc, LS3_REG_INTC_EDGE, mask, true);
+ ls_intc_set_bit(gc, LS3_REG_INTC_POL, mask, false);
+ break;
+ default:
+ return -EINVAL;
+ }
+
+ irqd_set_trigger_type(data, type);
+ return 0;
+}
+
+int __init ls3_iointc_of_init(struct device_node *node,
+ struct device_node *parent)
+{
+ struct irq_chip_generic *gc;
+ struct irq_chip_type *ct;
+ struct ls3_iointc_priv *priv;
+ int parent_irq, err = 0;
+ int core = cpu_logical_map(smp_processor_id());
Are you guaranteed to be in a non-preemptible section here?
Yes, as irqchip will be initialized even earlier than clockevent. There
must be non-preemptible.
+ int ip = 0;
+ int i;
+ const u32 *map_ip, *map_core;
+
+ priv = kzalloc(sizeof(*priv), GFP_KERNEL);
+ if (!priv)
+ return -ENOMEM;
+
+ priv->intc_base = of_iomap(node, 0);
+ if (!priv->intc_base) {
+ err = -ENODEV;
+ goto out_free_priv;
+ }
+
+ map_ip = of_get_property(node, "loongson,map-ip", NULL);
+ if (!map_ip)
+ goto no_ip;
+ else if ((*map_ip) > 5)
+ pr_err("* %pOF loongson,map-ip is invalid\n", node);
+ else
+ ip = (*map_ip);
What is this "ip"?
The interrupt line number of CPU (parent intc). As MIPS called CPU
interrupt registers "CAUSE_IP".
+no_ip:
+
+ /* If this property does not exist or invalid,
+ * we map all IRQs to bootcore.
+ */
Comment format.
+ map_core = of_get_property(node, "loongson,map-core", NULL);
+ if (!map_core)
+ goto no_core;
+ else if ((*map_core) > 3)
+ pr_err("* %pOF loongson,map-core is invalid\n", node);
+ else
+ core = (*map_core);
+no_core:
+
+ parent_irq = irq_of_parse_and_map(node, 0);
+ if (!parent_irq) {
+ pr_err("ls3-iointc: unable to get parent irq\n");
+ err = -ENODEV;
+ goto out_iounmap;
+ }
+ /* Set up an IRQ domain */
+ priv->domain = irq_domain_add_linear(node, 32, &irq_generic_chip_ops,
+ NULL);
+ if (!priv->domain) {
+ pr_err("ls3-iointc: cannot add IRQ domain\n");
+ err = -ENOMEM;
+ goto out_iounmap;
+ }
+
+ err = irq_alloc_domain_generic_chips(priv->domain, 32, 1,
+ node->full_name, handle_level_irq,
+ IRQ_NOPROBE, 0, 0);
+ if (err) {
+ pr_err("ls3-iointc: unable to register IRQ domain\n");
+ err = -ENOMEM;
+ goto out_free_domain;
+ }
+
+ /*
+ * Q: Why don't we set IRQ affinity by these registers?
+ * A: Hardware IRQ delivery is seriously broken,
+ * so we map all IRQs to a fixed core.
+ */
+ pr_info("ls3-iointc: Mapping All ls3-iointc IRQ to core %d, IP %d\n", core, ip);
+ for (i = 0; i < LS3_CHIP_IRQ; i++)
+ writeb(LS3_MAP_CORE_INT(core, ip), priv->intc_base + 0x1 * i);
This doesn't make much sense. If this is a chained irqchip, all
interrupts end-up on a single CPU (the one that handle the parent IRQ).
So how comes there is even a choice of picking a target CPU?
It's parent IRQ (mti,cpu-interrupt-controller) is a percpu IRQ.
In design, it allows us to decide affinity at runtime but actually
hardware is seriously broken.
Also, you still need to define a set_affinity() callback, even if it
returns -EINVAL.
+ priv->intc_base += LS3_INTC_CHIP_START;
+
+ /* Disable all IRQs */
+ writel(0xffffffff, priv->intc_base + LS3_REG_INTC_DISABLE);
+ /* Set to level triggered */
+ writel(0x0, priv->intc_base + LS3_REG_INTC_EDGE);
+
+ gc = irq_get_domain_generic_chip(priv->domain, 0);
+ gc->reg_base = priv->intc_base;
+ gc->domain = priv->domain;
+
+ ct = gc->chip_types;
+ ct->regs.enable = LS3_REG_INTC_ENABLE;
+ ct->regs.disable = LS3_REG_INTC_DISABLE;
+ ct->chip.irq_unmask = irq_gc_unmask_enable_reg;
+ ct->chip.irq_mask = irq_gc_mask_disable_reg;
+ ct->chip.irq_mask_ack = irq_gc_mask_disable_reg;
+ ct->chip.irq_set_type = ls_intc_set_type;
+
+ irq_set_chained_handler_and_data(parent_irq,
+ ls3_io_chained_handle_irq, priv);
+
+ return 0;
+
+out_free_domain:
+ irq_domain_remove(priv->domain);
+out_iounmap:
+ iounmap(priv->intc_base);
+out_free_priv:
+ kfree(priv);
+
+ return err;
+}
+
+IRQCHIP_DECLARE(ls3_iointc, "loongson,ls3-iointc", ls3_iointc_of_init);
Thanks,
M.