[RFC PATCH v2 31/31] kvx: Add IPI driver

[Yann Sionneau <ysionneau@kalray.eu>]

From: Jules Maselbas <jmaselbas@kalray.eu>

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

Co-developed-by: Clement Leger <clement@clement-leger.fr>
Signed-off-by: Clement Leger <clement@clement-leger.fr>
Co-developed-by: Guillaume Thouvenin <gthouvenin@kalray.eu>
Signed-off-by: Guillaume Thouvenin <gthouvenin@kalray.eu>
Co-developed-by: Julian Vetter <jvetter@kalray.eu>
Signed-off-by: Julian Vetter <jvetter@kalray.eu>
Co-developed-by: Luc Michel <lmichel@kalray.eu>
Signed-off-by: Luc Michel <lmichel@kalray.eu>
Signed-off-by: Jules Maselbas <jmaselbas@kalray.eu>
Signed-off-by: Yann Sionneau <ysionneau@kalray.eu>
---

Notes:
    V1 -> V2: new patch

 arch/kvx/include/asm/ipi.h |  16 ++++++
 arch/kvx/platform/Makefile |   1 +
 arch/kvx/platform/ipi.c    | 108 +++++++++++++++++++++++++++++++++++++
 3 files changed, 125 insertions(+)
 create mode 100644 arch/kvx/include/asm/ipi.h
 create mode 100644 arch/kvx/platform/ipi.c

diff --git a/arch/kvx/include/asm/ipi.h b/arch/kvx/include/asm/ipi.h
new file mode 100644
index 000000000000..137407a075e6
--- /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_probe(irqreturn_t (*ipi_irq_handler)(int, void *));
+
+void kvx_ipi_send(const struct cpumask *mask);
+
+#endif /* _ASM_KVX_IPI_H */
diff --git a/arch/kvx/platform/Makefile b/arch/kvx/platform/Makefile
index c7d0abb15c27..27f0914e0de5 100644
--- a/arch/kvx/platform/Makefile
+++ b/arch/kvx/platform/Makefile
@@ -4,3 +4,4 @@
 #
 
 obj-$(CONFIG_SMP) += pwr_ctrl.o
+obj-$(CONFIG_SMP) += ipi.o
diff --git a/arch/kvx/platform/ipi.c b/arch/kvx/platform/ipi.c
new file mode 100644
index 000000000000..a471039b1643
--- /dev/null
+++ b/arch/kvx/platform/ipi.c
@@ -0,0 +1,108 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (C) 2017-2023 Kalray Inc.
+ * Author(s): Clement Leger
+ *            Luc Michel
+ */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/io.h>
+#include <linux/slab.h>
+#include <linux/types.h>
+#include <linux/module.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>
+
+#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)
+
+struct kvx_ipi_ctrl {
+	void __iomem *regs;
+	unsigned int ipi_irq;
+};
+
+static struct kvx_ipi_ctrl kvx_ipi_controller;
+
+/**
+ * @kvx_pwr_ctrl_cpu_poweron Wakeup a cpu
+ *
+ * cpu: cpu to wakeup
+ */
+void kvx_ipi_send(const struct cpumask *mask)
+{
+	const unsigned long *maskb = cpumask_bits(mask);
+
+	WARN_ON(*maskb & KVX_IPI_CPU_MASK);
+	writel(*maskb, kvx_ipi_controller.regs + IPI_INTERRUPT_OFFSET);
+}
+
+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;
+}
+
+int __init kvx_ipi_ctrl_probe(irqreturn_t (*ipi_irq_handler)(int, void *))
+{
+	struct device_node *np;
+	int ret;
+	unsigned int ipi_irq;
+	void __iomem *ipi_base;
+
+	np = of_find_compatible_node(NULL, NULL, "kalray,kvx-ipi-ctrl");
+	BUG_ON(!np);
+
+	ipi_base = of_iomap(np, 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(np, 0);
+	of_node_put(np);
+	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;
+	}
+
+	return 0;
+}
-- 
2.37.2