[PATCH 2/2] power: reset: add a QEMU RISC-V virt machine poweroff driver

From: Christoph Hellwig <hch@lst.de>
To: Sebastian Reichel <sre@kernel.org>,
	Rob Herring <robh+dt@kernel.org>,
	Mark Rutland <mark.rutland@arm.com>,
	Paul Walmsley <paul.walmsley@sifive.com>,
	Palmer Dabbelt <palmer@dabbelt.com>
Cc: linux-pm@vger.kernel.org, devicetree@vger.kernel.org,
	linux-riscv@lists.infradead.org
Subject: [PATCH 2/2] power: reset: add a QEMU RISC-V virt machine poweroff driver
Date: Thu,  7 Nov 2019 22:24:08 +0100	[thread overview]
Message-ID: <20191107212408.11857-3-hch@lst.de> (raw)
In-Reply-To: <20191107212408.11857-1-hch@lst.de>

Add a trivial poweroff driver for the qemu-virt test device that
allows an oderly shutdown of the VM.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 arch/riscv/configs/defconfig                  |  2 +
 drivers/power/reset/Kconfig                   |  8 ++++
 drivers/power/reset/Makefile                  |  1 +
 .../power/reset/qemu-riscv-virt-poweroff.c    | 47 +++++++++++++++++++
 4 files changed, 58 insertions(+)
 create mode 100644 drivers/power/reset/qemu-riscv-virt-poweroff.c

diff --git a/arch/riscv/configs/defconfig b/arch/riscv/configs/defconfig
index 420a0dbef386..47da87725b5e 100644
--- a/arch/riscv/configs/defconfig
+++ b/arch/riscv/configs/defconfig
@@ -63,6 +63,8 @@ CONFIG_HW_RANDOM_VIRTIO=y
 CONFIG_SPI=y
 CONFIG_SPI_SIFIVE=y
 # CONFIG_PTP_1588_CLOCK is not set
+CONFIG_POWER_RESET=y
+CONFIG_QEMU_RISCV_VIRT_POWEROFF=y
 CONFIG_DRM=y
 CONFIG_DRM_RADEON=y
 CONFIG_DRM_VIRTIO_GPU=y
diff --git a/drivers/power/reset/Kconfig b/drivers/power/reset/Kconfig
index a564237278ff..56cb18520850 100644
--- a/drivers/power/reset/Kconfig
+++ b/drivers/power/reset/Kconfig
@@ -256,5 +256,13 @@ config NVMEM_REBOOT_MODE
 	  then the bootloader can read it and take different
 	  action according to the mode.
 
+config QEMU_RISCV_VIRT_POWEROFF
+	tristate "QEMU RISC-V virt machine poweroff driver"
+	depends on OF
+	depends on RISCV || COMPILE_TEST
+	help
+	  Say y here to allow RISC-V Qemu VMs to be shut down by
+	  the kernel.
+
 endif
 
diff --git a/drivers/power/reset/Makefile b/drivers/power/reset/Makefile
index 85da3198e4e0..b3094016b634 100644
--- a/drivers/power/reset/Makefile
+++ b/drivers/power/reset/Makefile
@@ -30,3 +30,4 @@ obj-$(CONFIG_REBOOT_MODE) += reboot-mode.o
 obj-$(CONFIG_SYSCON_REBOOT_MODE) += syscon-reboot-mode.o
 obj-$(CONFIG_POWER_RESET_SC27XX) += sc27xx-poweroff.o
 obj-$(CONFIG_NVMEM_REBOOT_MODE) += nvmem-reboot-mode.o
+obj-$(CONFIG_QEMU_RISCV_VIRT_POWEROFF) += qemu-riscv-virt-poweroff.o
diff --git a/drivers/power/reset/qemu-riscv-virt-poweroff.c b/drivers/power/reset/qemu-riscv-virt-poweroff.c
new file mode 100644
index 000000000000..5b9a12dd853b
--- /dev/null
+++ b/drivers/power/reset/qemu-riscv-virt-poweroff.c
@@ -0,0 +1,47 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (c) 2019 Christoph Hellwig.
+ */
+
+#include <linux/reboot.h>
+#include <linux/init.h>
+#include <linux/io.h>
+#include <linux/platform_device.h>
+#include <linux/of_address.h>
+#include <linux/module.h>
+
+#define VIRT_TEST_FINISHER_PASS         0x5555
+
+static u16 __iomem *test_addr;
+
+static void qemu_virt_power_off(void)
+{
+	writew(VIRT_TEST_FINISHER_PASS, test_addr);
+}
+
+static int sifive_test_probe(struct platform_device *pdev)
+{
+	/* there can only be a single instance */
+	if (WARN_ON_ONCE(test_addr))
+		return -EINVAL;
+
+	test_addr = of_iomap(pdev->dev.of_node, 0);
+	if (!test_addr)
+		return -EINVAL;
+	pm_power_off = qemu_virt_power_off;
+	return 0;
+}
+
+static const struct of_device_id sifive_test_of_match[] = {
+	{ .compatible = "sifive,test0", },
+	{},
+};
+
+static struct platform_driver sifive_test_driver = {
+	.probe			= sifive_test_probe,
+	.driver = {
+		.name		= "sifive_test",
+		.of_match_table = sifive_test_of_match,
+	},
+};
+module_platform_driver(sifive_test_driver);
-- 
2.20.1

