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

[Paul Walmsley <paul.walmsley@sifive.com>]

On Thu, 7 Nov 2019, Christoph Hellwig wrote:

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

"orderly"

> 
> 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.

Same comments here and below as 

https://lore.kernel.org/linux-riscv/mhng-0dedc685-73d2-4e7f-b608-69385a6e7a99@palmer-si-x1c4/T/#t

there's nothing that should be RISC-V specific here.

> +
>  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
> 
> 


- Paul

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