[RFC PATCH v3 35/37] kvx: Add IPI driver

ysionneau
2024-07-22T09:43:55Z

From: Yann Sionneau <ysionneau@kalrayinc.com>

The Inter-Processor Interrupt Controller (IPI) provides a fast
synchronization mechanism to the software. It exposes eight independent
sets of registers that can be used to notify each processor in the cluster.

Co-developed-by: Clement Leger <clement@clement-leger.fr>
Signed-off-by: Clement Leger <clement@clement-leger.fr>
Co-developed-by: Guillaume Thouvenin <thouveng@gmail.com>
Signed-off-by: Guillaume Thouvenin <thouveng@gmail.com>
Co-developed-by: Julian Vetter <jvetter@kalrayinc.com>
Signed-off-by: Julian Vetter <jvetter@kalrayinc.com>
Co-developed-by: Luc Michel <luc@lmichel.fr>
Signed-off-by: Luc Michel <luc@lmichel.fr>
Signed-off-by: Jules Maselbas <jmaselbas@zdiv.net>
Signed-off-by: Yann Sionneau <ysionneau@kalrayinc.com>
---

Notes:
V1 -> V2: new patch
V2 -> V3:
- Restructured IPI code according to reviewer feedback
- move from arch/kvx/platform to drivers/irqchip/
- remove bogus comment
- call set_smp_cross_call() to set smpboot.c's ipi function pointer
- feedbacks: https://lore.kernel.org/bpf/Y8qlOpYgDefMPqWH@zx2c4.com/T/#mb02884ea498e627c2621973157330f2ea9977190
---
arch/kvx/include/asm/ipi.h | 16 ++++
drivers/irqchip/Kconfig | 4 +
drivers/irqchip/Makefile | 1 +
drivers/irqchip/irq-kvx-ipi-ctrl.c | 143 +++++++++++++++++++++++++++++
4 files changed, 164 insertions(+)
create mode 100644 arch/kvx/include/asm/ipi.h
create mode 100644 drivers/irqchip/irq-kvx-ipi-ctrl.c

diff --git a/arch/kvx/include/asm/ipi.h b/arch/kvx/include/asm/ipi.h
new file mode 100644
index 0000000000000..a23275d19d225
--- /dev/null
+++ b/arch/kvx/include/asm/ipi.h
@@ -0,0 +1,16 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Copyright (C) 2017-2023 Kalray Inc.
+ * Author(s): Clement Leger
+ */
+
+#ifndef _ASM_KVX_IPI_H
+#define _ASM_KVX_IPI_H
+
+#include <linux/irqreturn.h>
+
+int kvx_ipi_ctrl_init(struct device_node *node, struct device_node *parent);
+
+void kvx_ipi_send(const struct cpumask *mask, unsigned int operation);
+
+#endif /* _ASM_KVX_IPI_H */
diff --git a/drivers/irqchip/Kconfig b/drivers/irqchip/Kconfig
index da1dbd79dab54..65db9990cf475 100644
--- a/drivers/irqchip/Kconfig
+++ b/drivers/irqchip/Kconfig
@@ -337,6 +337,10 @@ config KVX_CORE_INTC
depends on KVX
select IRQ_DOMAIN

+config KVX_IPI_CTRL
+ bool
+ depends on KVX
+
config KVX_APIC_GIC
bool
depends on KVX
diff --git a/drivers/irqchip/Makefile b/drivers/irqchip/Makefile
index 30b69db8789f7..f8fa246df74d2 100644
--- a/drivers/irqchip/Makefile
+++ b/drivers/irqchip/Makefile
@@ -69,6 +69,7 @@ obj-$(CONFIG_BRCMSTB_L2_IRQ) += irq-brcmstb-l2.o
obj-$(CONFIG_KEYSTONE_IRQ) += irq-keystone.o
obj-$(CONFIG_MIPS_GIC) += irq-mips-gic.o
obj-$(CONFIG_KVX_CORE_INTC) += irq-kvx-core-intc.o
+obj-$(CONFIG_KVX_IPI_CTRL) += irq-kvx-ipi-ctrl.o
obj-$(CONFIG_KVX_APIC_GIC) += irq-kvx-apic-gic.o
obj-$(CONFIG_KVX_ITGEN) += irq-kvx-itgen.o
obj-$(CONFIG_KVX_APIC_MAILBOX) += irq-kvx-apic-mailbox.o
diff --git a/drivers/irqchip/irq-kvx-ipi-ctrl.c b/drivers/irqchip/irq-kvx-ipi-ctrl.c
new file mode 100644
index 0000000000000..09d955a5c109a
--- /dev/null
+++ b/drivers/irqchip/irq-kvx-ipi-ctrl.c
@@ -0,0 +1,143 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (C) 2017-2024 Kalray Inc.
+ *
+ * Author(s): Clement Leger
+ * Jonathan Borne
+ * Luc Michel
+ */
+
+#define pr_fmt(fmt) "kvx_ipi_ctrl: " fmt
+
+#include <linux/smp.h>
+#include <linux/io.h>
+#include <linux/slab.h>
+#include <linux/types.h>
+#include <linux/module.h>
+#include <linux/irqchip.h>
+#include <linux/of_irq.h>
+#include <linux/cpumask.h>
+#include <linux/interrupt.h>
+#include <linux/cpuhotplug.h>
+#include <linux/of_address.h>
+#include <linux/of_platform.h>
+
+#include <asm/ipi.h>
+
+#define IPI_INTERRUPT_OFFSET 0x0
+#define IPI_MASK_OFFSET 0x20
+
+/*
+ * IPI controller can signal RM and PE0 -> 15
+ * In order to restrict that to the PE, write the corresponding mask
+ */
+#define KVX_IPI_CPU_MASK (~0xFFFF)
+
+/* A collection of single bit ipi messages. */
+static DEFINE_PER_CPU_ALIGNED(unsigned long, ipi_data);
+
+struct kvx_ipi_ctrl {
+ void __iomem *regs;
+ unsigned int ipi_irq;
+};
+
+static struct kvx_ipi_ctrl kvx_ipi_controller;
+
+void kvx_ipi_send(const struct cpumask *mask, unsigned int operation)
+{
+ const unsigned long *maskb = cpumask_bits(mask);
+ unsigned long flags;
+ int cpu;
+
+ /* Set operation that must be done by receiver */
+ for_each_cpu(cpu, mask)
+ set_bit(operation, &per_cpu(ipi_data, cpu));
+
+ /* Commit the write before sending IPI */
+ smp_wmb();
+
+ local_irq_save(flags);
+
+ WARN_ON(*maskb & KVX_IPI_CPU_MASK);
+ writel(*maskb, kvx_ipi_controller.regs + IPI_INTERRUPT_OFFSET);
+
+ local_irq_restore(flags);
+}
+
+static int kvx_ipi_starting_cpu(unsigned int cpu)
+{
+ enable_percpu_irq(kvx_ipi_controller.ipi_irq, IRQ_TYPE_NONE);
+
+ return 0;
+}
+
+static int kvx_ipi_dying_cpu(unsigned int cpu)
+{
+ disable_percpu_irq(kvx_ipi_controller.ipi_irq);
+
+ return 0;
+}
+
+static irqreturn_t ipi_irq_handler(int irq, void *dev_id)
+{
+ unsigned long *pending_ipis = &per_cpu(ipi_data, smp_processor_id());
+
+ while (true) {
+ unsigned long ops = xchg(pending_ipis, 0);
+
+ if (!ops)
+ return IRQ_HANDLED;
+
+ handle_IPI(ops);
+ }
+
+ return IRQ_HANDLED;
+}
+
+int __init kvx_ipi_ctrl_init(struct device_node *node,
+ struct device_node *parent)
+{
+ int ret;
+ unsigned int ipi_irq;
+ void __iomem *ipi_base;
+
+ BUG_ON(!node);
+
+ ipi_base = of_iomap(node, 0);
+ BUG_ON(!ipi_base);
+
+ kvx_ipi_controller.regs = ipi_base;
+
+ /* Init mask for interrupts to PE0 -> PE15 */
+ writel(KVX_IPI_CPU_MASK, kvx_ipi_controller.regs + IPI_MASK_OFFSET);
+
+ ipi_irq = irq_of_parse_and_map(node, 0);
+ if (!ipi_irq) {
+ pr_err("Failed to parse irq: %d\n", ipi_irq);
+ return -EINVAL;
+ }
+
+ ret = request_percpu_irq(ipi_irq, ipi_irq_handler,
+ "kvx_ipi", &kvx_ipi_controller);
+ if (ret) {
+ pr_err("can't register interrupt %d (%d)\n",
+ ipi_irq, ret);
+ return ret;
+ }
+ kvx_ipi_controller.ipi_irq = ipi_irq;
+
+ ret = cpuhp_setup_state(CPUHP_AP_IRQ_KVX_STARTING,
+ "kvx/ipi:online",
+ kvx_ipi_starting_cpu,
+ kvx_ipi_dying_cpu);
+ if (ret < 0) {
+ pr_err("Failed to setup hotplug state");
+ return ret;
+ }
+
+ set_smp_cross_call(kvx_ipi_send);
+ pr_info("controller probed\n");
+
+ return 0;
+}
+IRQCHIP_DECLARE(kvx_ipi_ctrl, "kalray,coolidge-ipi-ctrl", kvx_ipi_ctrl_init);
--
2.45.2